9. ECOLOGICAL IMPACT

9.1 Introduction

Scope

9.1.1 The objectives of the ecological impact assessment are:

· To establish an ecological baseline for the assessment area, focusing on identified key areas and key species groups;
· To assess the ecological implications of the project components, individually and collectively, with reference to the baseline;
· To develop feasible and effective mitigation measures for significant impacts; and
· To determine whether residual, post-mitigation impacts are acceptable, and thus whether the project as a whole is ecologically acceptable; and
· This section of the EIA summarises findings of literature review and field surveys undertaken from August 2001 through June 2002. Detailed results of field surveys carried out during that time period were presented in Appendix 9A "Ecological Survey Results".

9.1.2 This ecological impact assessment contains a full and detailed identification and assessment of impacts of the project components and related issues based on current proposals and data; an outline of potential mitigation measures; and an assessment of the acceptability of residual impacts. This assessment also utilises information already presented in previous chapters of this report.

9.1.3 This ecological impact assessment is based upon the preferred alignment option selected and recommended during the present EIA study (i.e. S-curve bridge)(Figure 9.1). Details of the alignment option selection please refer to Section 4 of this EIA Report.

9.2 Environmental Legislation, Policies, Plans, Standards and Criteria

9.2.1 HKSAR Government ordinances and regulations relevant to this assessment include the following:

· The Forests and Countryside Ordinance (Cap. 96) and its subsidiary legislation, the Forestry Regulations;
· The Town Planning Ordinance (Cap. 131);
· The Wild Animals Protection Ordinance (Cap. 170);
· The Animals and Plants (Protection of Endangered Species) Ordinance (Cap. 187);
· The Country Parks Ordinance (Cap. 208) and its subsidiary legislation;
· The Marine Parks Ordinance (Cap. 476); and
· The Environmental Impact Assessment Ordinance (Cap. 499) and the associated Technical Memorandum on Environmental Impact Assessment Process ("the EIAO-TM").

9.2.2 This study makes reference to the following standards, guidelines and other documents of the HKSAR Government:

· Hong Kong Planning Standards and Guidelines (HKPSG) Chapter 10, "Conservation", which provides guidelines on incorporating nature conservation objectives into landuse planning and new development;
· PELB Technical Circular 1/97 / Works Branch Technical Circular 4/97, "Guidelines for Implementing the Policy on Off-site Ecological Mitigation Measures" ("the TC"), which sets out guidelines for implementation of Government policy on ecological mitigation, particularly off-site mitigation;
· The Deep Bay Guidelines prepared by ERL Asia as part of the Deep Bay Environmental Management Review, which outline measures intended to ensure that dredging, reclamation and drainage works in Deep Bay respect the environmental value and sensitivity of the area;
· EIAO Guidance Note No. 6/2002, "Some Observations on Ecological Assessment from the Environmental Impact Assessment Ordinance Perspective", dated January 2002, AFCD in conjunction with EPD; and
· EIAO Guidance Note No. 7/2002, "Ecological Baseline Survey for Ecological Assessment", dated January 2002, Nature Conservation & Marine Conservation Divisions, AFCD in conjunction with EPD.

9.2.3 This assessment also makes note of the following Mainland legislation and information :

· The Wild Animal Protection Law of the People's Republic of China;
· Regulations of the People's Republic of China for Implementation of the Protection of Terrestrial Wild Animals;
· Regulations of the People's Republic of China for Implementation of the Protection of Aquatic Wild Animals;
· List of State Protected Wild Animals, promulgated by the State Council;
· Marine Environmental Protection Law of the People's Republic of China; and
· Nature Reserve Regulations of the People's Republic of China.

9.2.4 This assessment also makes note of the following relevant international conventions:

· Convention on Wetlands of International Importance Especially as Waterfowl Habitat (the "Ramsar Convention"). The Ramsar Convention applies to both the HKSAR and the Mainland. It requires parties to conserve and make wise use of wetland areas, particularly those supporting waterfowl populations. The Mai Po Marshes and parts of Inner Deep Bay were declared a Wetland of International Importance under the Convention (a "Ramsar Site") in 1995 based on their importance to migratory waterbirds.

· Convention on the Conservation of Migratory Species of Wild Animals (the "Bonn Convention"). This Convention applies to the HKSAR but not to the Mainland. The Bonn Convention is intended to provide strict protection for Appendix I species (those in danger of extinction throughout all or a significant portion of their range), and to encourage Range States for such species to conclude agreements for the conservation and management of Appendix II species (migratory species which have an unfavourable conservation status and require international agreements for their conservation, or which have a conservation status which would significantly benefit from international co-operation). Five bird species found in Deep Bay are Appendix I species: Dalmatian Pelican Pelecanus crispus, Swinhoe's Egret Egretta eulophotes, Oriental White Stork Ciconia boyciana, Relict Gull Larus relictus, and Saunders' Gull Larus saundersi.

· Convention on International Trade in Endangered Species of Wild Fauna and Flora ("CITES"). This Convention regulates international trade in animal and plant species considered to be at risk from such trade. The main categories of species relevant to Hong Kong are Appendices I and II. Species listed in Appendix I are species threatened with extinction that are or may be affected by trade; species listed in Appendix II are those that, while not necessarily under current threat of extinction, may become threatened unless trade is subject to strict regulation. Hong Kong's obligations under this Convention are enforced via the Animals and Plants (Protection of Endangered Species) Ordinance.

· United Nations Convention on Biological Diversity. This convention requires parties to regulate or manage biological resources important for the conservation of biological diversity whether within or outside protected areas, with a view to ensuring their conservation and sustainable use. It also requires parties to promote the protection of ecosystems, natural habitats and the maintenance of viable populations of species in natural surroundings. The People's Republic of China is a party to the Convention, while the HKSAR Government has stated that it is "committed to meeting the environmental objectives" of the Convention (PELB 1996).

9.3 Literature Review and Field Survey Methods

9.3.1 Ecological Baseline Conditions for this EIA are derived from both literature review and field surveys. The purpose of literature review and field study is to obtain adequate data to allow accurate prediction of the project's likely impacts upon the ecology of the assessment area, particularly those aspects singled out for special attention in Section 3.4.5.4 (vi) of the Study Brief: "intertidal mudflat; mangrove; seagrass bed; avifauna, in particular, Black-faced Spoonbill (Platalea minor); egretries; inter-tidal and sub-tidal benthic faunal communities; Chinese White Dolphin (Sousa chinensis); Horseshoe crabs; and any other habitats and wildlife groups identified as having special conservation interests by this EIA study". Section 3.4.5.4 (i) of the Study Brief directs that related studies should be reviewed, in particular the Feasibility Study for Additional Cross-border Links Stage 2 (Mouchel 2000, hereafter referred to as"Crosslinks2"), and the concurrent Deep Bay Link EIA study. An eleven-month field study was performed from August 2001 to June 2002. A thorough literature review on bird collision and an Additional Bird-Bridge Survey on bridge structures in Hong Kong and Macau were also conducted.

Literature Review

Terrestrial Vegetation and Habitats

9.3.2 Literature reviewed for information on vegetation and habitats included Xing et al. (2000) and Thrower (1988) and other Urban Council publications on plant species; AFD (1995) on agricultural lands and fish ponds; the Register of SSSIs (Anon. 1995a) on SSSIs of vegetative importance; Dudgeon and Chan (1996) on freshwater wetlands; Weatherhead (undated) on Pitcher Plants Nepenthes mirabilis; Barretto and Chau (1996) on the wetland orchid Liparis ferruginea; and Chu (1998) and Chu and Xing (1997) on fung shui woods.

9.3.3 Major EIA studies reviewed for information included the Feasibility Study for Additional Cross-border Links Stage 2 (Mouchel 1999), and Deep Bay Link: Investigation and Preliminary Design - Final EIA Report (Arup 2002).

Stream Habitats

9.3.4 Literature reviewed for information on streams in the Western New Territories included EPD (2001b) for information on water quality, and the Feasibility Study for Additional Cross-border Links Stage 2 (Mouchel 1999).

Terrestrial Invertebrates

9.3.5 Information on status and distribution of some terrestrial invertebrate taxa in Hong Kong was obtained from Wilson (1995), Wilson (1997), Walthew (1997), Reels and Walthew (1998), and Bascombe et al. (1999). The only systematic study of terrestrial invertebrates in the study area located during literature review was Dudgeon and Chan (1996) on freshwater invertebrates. The consultants liased with local experts on butterflies and dragonflies to locate additional records for the study area. Interim findings of the Terrestrial Biodiversity Survey of the University of Hong Kong were obtained from Lau et al. (1996). Mouchel (1999) was also reviewed for records specific to the study area.

Reptiles and Amphibians

9.3.6 Literature reviewed for records of reptiles and amphibians in and around the study area included Karsen et al. (1986); Lau (1995); Dudgeon and Chan (1996); Lau and Dudgeon (1999); ecological monitoring results for the WENT Landfill (Shea et al. 1995); Porcupine! (the newsletter of the Department of Ecology and Biodiversity, University of Hong Kong); and the Feasibility Study for Additional Cross-border Links Stage 2 (Mouchel 1999). Interim findings of the Terrestrial Biodiversity Survey of the University of Hong Kong were obtained from Lau et al. (1996).

Avifauna

9.3.7 Literature reviewed for information on birds included the Hong Kong Bird Report; records of the Hong Kong Bird Watching Society; reports of the Hong Kong Bird Watching Society waterfowl counts; Porcupine! (newsletter of the Department of Ecology and Biodiversity, University of Hong Kong); the Register of SSSIs (Anon. 1995a) for SSSIs of ornithological interest; Chen et al. (1997) on birds at Futian; Melville et al. (1994) on bird use of fish ponds; Wong (1991), Pearson (1993), Young (1993), Young and Cha (1995), Carey (1999a), Wong et al. (2000), Kwok et al. (2001) and Wong and Kwok (2002) on breeding and feeding ecology of herons and egrets; and Viney et al. (1996), Diskin (1997), Xu (1995), Carey and Young (1999) for waterfowls in the Inner Deep Bay Ramsar Site and Zheng and Wang (1998) for general information; WWF (2001a, 2001b, 2001c) for Black-faced Spoonbills (BFSs) and their conservation management in Hong Kong; and Dahmer and Felley (in prep.) for local, regional, and global BFS population estimates; Carey et al. (2001) for results of Hong Kong Breeding Bird Survey. Interim findings of the Terrestrial Biodiversity Survey of the University of Hong Kong were obtained from Lau et al. (1996).

9.3.8 EIA studies reviewed for information included the EIA for the Shenzhen River Regulation Project (Peking University undated); and the Feasibility Study for Additional Cross-border Links Stage 2 (Mouchel 1999).

9.3.9 A thorough literature review was also conducted to investigate the potential of bird fatalities caused by bird collision with bridges (see Appendix 9B).

Terrestrial Mammals

9.3.10 Literature reviewed for information on terrestrial mammals included Reels (1996), the EIA for the Black Point Power Station (ERL 1992); the EIA for the KCRC Western Corridor Railway (ERM 1998); studies conducted for the Route 3 Highway; ecological monitoring studies for the WENT Landfill (Shea et al. 1995); and the Feasibility Study for Additional Cross-border Links Stage 2 (Mouchel 1999). Interim findings of the Terrestrial Biodiversity Survey of the University of Hong Kong were obtained from Lau et al. (1996).

Coastal and Intertidal Habitats and Associated Invertebrate Fauna

9.3.11 Literature reviewed for information on coastal habitats and associated invertebrate fauna in Deep Bay and the Western New Territories included the Register of SSSIs (Anon. 1995a) for information on coastal SSSIs; Morton and Morton (1983) on general coastal ecology in Hong Kong; Irving and Morton (1984), Lee (1993, 1999), Peking University (undated), Melville et al. (1997) and other sources on the Mai Po area; Hodgkiss and Morton (1983), SWIMS (1994), Wong (1998), and Fong (1998 & 1999) on seagrass; Tam and Wong (1997) on mangrove communities and associated fauna; and Liang and Zhou (1987), Sekiguchi (1988), Huang (1997), and Chiu & Morton (1999) on horseshoe crab ecology.

9.3.12 EIA studies reviewed for information included the EIA for the WENT Landfill (MHA 1987); the EIA for the Shenzhen River Regulation Project (Peking University undated); the EIA for the Black Point Power Station (ERL 1992, ERM 1993); the EIA of the Aviation Fuel Receiving Facility at Sha Chau (ERM 1995); the EIA for Tin Shui Wai Development (Binnie 1997); and the Feasibility Study for Additional Cross-border Links Stage 2 (Mouchel 1999).

9.3.13 Mainland literature reviewed for information on intertidal ecology of the Pearl River Estuary and Guangdong coast included Yu et al. (1990a, 1990b).

Estuarine Habitats, Fish and Benthos

9.3.14 The following academic studies and reports were reviewed: EPD (2001a) and Smith-Evans and Dawes (1996) on water quality; Richards and Wu (1985) and Ni (1997) on fish communities in north Lantau waters; and Lee (1999) on benthos.

9.3.15 EIA studies reviewed for information included studies for the EIA for the WENT Landfill (MHA 1987); the EIA for the Tap Shek Kok Power Station (Lam 1987); the EIA for the Black Point Power Station (ERL 1992, ERM 1993); the EIA for the Island Transfer Station (Dredging of WENT Fairway) (ERL 1993); the EIA for the Aviation Fuel Receiving Facility at Sha Chau (ERM 1995); the EIA for Disposal of Contaminated Mud in the East Sha Chau Marine Borrow Pit (ERM 1997); and the Feasibility Study for Additional Cross-border Links Stage 2 (Mouchel 1999).

9.3.16 A review of Mainland literature was also conducted as a general background for the current assessment. Sources reviewed included Huang (1986), He and Lin (1988), Zheng (1989), Chen (1990), He and Li (1991), Wu and Lin (1992), Wang (1993), Chen et al. (1995), Fu et al. (1995), and Zhan (1996) on marine fauna and ecology.

Cetaceans

9.3.17 Study of cetaceans focused on the Indo-Pacific Hump-backed Dolphin (Chinese White Dolphin) Sousa chinensis, the only species known to be resident near the assessment area. Literature reviewed included the major reports by Jefferson (1998, 2000), which summarise results of systematic surveys in HKSAR waters and discuss ecology, distribution, abundance and conservation, as well as providing preliminary results on distribution elsewhere in Lingdingyang. Additional sources reviewed included Chen and Wu (1997), Yang (1997) and Wang (1998) in Mainland waters, and Parsons (1997) in HKSAR waters.

Field Survey Methodology

9.3.18 The programme of field study was designed to meet the requirements of the Study Brief by filling data gaps identified during literature review that would prevent adequate assessment of ecological impacts of the project. Field studies focused on habitats and species mentioned in the Study Brief, where adequate data on these were not available, and on the habitats and species singled out as important in Annex 16 of the Technical Memorandum on Environmental Impact Assessment Process: specifically "important habitats where an ecological assessment will be necessary" and "species of conservation importance" (EIAO-TM, Annex 16, Appendix A, Notes 2 and 3). This report often uses the words "conservation concern" rather than "conservation importance" because the former is typically readily demonstrable whereas the latter can lead to debate.

9.3.19 Field survey programme of the present project was planned to be an extension of the field surveys for Crosslink2 EIA study. A 12-month survey was conducted for CrossLink2 between 1998-1999. Fieldwork for the present project began in August 2001 and continued through June 2002 to provide another 11 months of survey data covering seasonal variation and the breeding season and spring migration of birds. The requirement in the Study Brief was "at least 6 months".

9.3.20 At the initial phase of the present field studies habitats and species in lowland and coastal zones, particularly those along the outer Deep Bay coast, had been identified as key issues for ecology within the assessment area. The following paragraphs outline the objectives, scheduling and methodology of field studies. Due to the clarification of the demarcation mark between the SWC project and the adjacent Deep Bay Link project, the Assessment Area for the SWC was re-defined as the area below the high water mark. The terrestrial part of the area covered by the field surveys of the SWC project is re-named as Study Area, and the information collected in which is used primarily for supplementary purposes.

Terrestrial Vegetation and Habitats

9.3.21 Studies of terrestrial habitats and vegetation were designed to cover the four initial proposed bridge landfalls and lands within 500 m of either side of the landfalls, or the area likely to be impacted by the project (Study Area). Macro-habitats were mapped on 1:5000 maps (reproduced on A3 size sheets in 1:50000 scale for presentation purposes). Mapping was based on Mouchel (1999), HKSAR Government aerial photos taken in 2000, and ground truthing. Habitat classification follows Crosslinks2 (Mouchel 1999) for consistency and comparison. Colour photographs were taken to provide views of representative and significant habitat types and important species recorded within the Study Area, together with other identified features of ecological importance.

9.3.22 Wet-season field surveys were conducted from September through October 2001 to describe habitats and record plant species and their relative abundance in each representative habitat type. Field surveys were conducted from November through March 2002 in the dry season and April 2002 in the early wet season to update habitat boundaries and plant species list.

9.3.23 Efforts were made to find species protected under local regulations or known to be uncommon or rare on a regional or territorial basis. The focus was on Pitcher Plants (Nepenthes mirabilis) and possibly orchids in the ravine woodlands/shrublands. Surveys for Pitcher Plants were performed along major streams within the Study Area. Qualitative surveys were carried out by visual observation of individuals or populations on stream banks.

Stream Habitats

9.3.24 The study of stream habitats covered the streams at Ngau Hom Shek and Sheung Pak Nai because they are near the proposed bridge landfall and connecting highway alignment. Stream sampling was conducted in September 2001 (wet season) and in February 2002 (dry season).
Terrestrial Invertebrates

9.3.25 Surveys for selected groups of terrestrial invertebrates covered the bridge landfall and proposed highway alignment. Invertebrate groups surveyed included Lepidoptera (specifically butterflies) and Odonata (dragonflies), two groups which are relatively well studied and for which baseline data covering much of Hong Kong already exist. Targeting surveys at these two groups has two major advantages: (1) there are far fewer difficulties in taxonomy and identification as compared to other groups of insects, facilitating preparation of a species list and determination of species diversity; (2) the commonness and distribution, degree of habitat restriction and habitat uses of species in these two orders is better studied locally/regionally than that of other orders, making it possible to determine the proportion of uncommon and rare species at a given site.

9.3.26 Butterflies and dragonflies were surveyed starting in September 2001 with the use of sweep nets and visual surveys at selected sites including freshwater wetlands, shrubland and streams. Sites were selected based on criteria including habitat patch size and accessibility. Survey locations coincide with bird sampling areas: the 3 fish pond clusters from Ngau Hom Shek to Sheung Pak Nai and upland bird point-count sites at Ngau Hom Shek (see following section and Figure 9.2 for locations). Surveys were conducted between September and May 2002.

Reptiles and Amphibians

9.3.27 Study of amphibians and reptiles covered the bridge landfall and proposed highway alignment. Surveys were conducted at and near bird sampling sites in fishpond clusters from Ngau Hom Shek to Sheung Pak Nai; and at the bird point-count survey area at Ngau Hom Shek (see Figure 9.2). Habitats surveyed included fishponds, streams, orchards and cultivated lands.

9.3.28 Anurans (frogs and toads) are surveyed non-systematically by recording vocalisations, direct observations, and roadkills. Amphibians are normally nocturnal and secretive, and it is most efficient to survey anurans by identification of their calls during the breeding season. This was done in May 2002. Reptiles were surveyed non-systematically during the course of other surveys. Reptiles typically occur at relatively low densities, therefore systematic survey is normally less effective than active searching in the microhabitats where they are usually found.

Avifauna

9.3.29 The study area for birds includes the bridge landfall and proposed highway alignment. Four-season surveys (late breeding season, autumn migration, winter, and spring migration) are underway to characterise the bird community utilising sites of potential importance to avifauna. Prior to the Crosslinks2 EIA the sites to be studied under the SWC project were poorly recorded in Hong Kong Bird Watching Society records. Crosslinks2 developed a more complete bird list for the sites (Mouchel 1999) during four seasons of survey. Bird studies carried out for the SWC project were not designed to add species to the Mouchel (1999) lists. Rather, the focus is upon quantification of bird use of various important habitats to provide a means of evaluating the relative importance of bird habitats, and to provide a reliable, repeatable, quantitative baseline for use in future comparisons with construction phase or operation phase monitoring studies.

9.3.30 Upland surveys: Due to extreme levels of fragmentation and human disturbance (e.g., hill fires) upland hillsides were not identified as bird habitats of potential importance. However, point-count systematic surveys of birds were conducted in upland habitats at Ngau Hom Shek in the interest of completeness and provision of quantitative information. Surveys to date were carried out in late breeding season 2001 (September), autumn 2001, winter 2001-2, and spring 2002. Three point counts were carried out at each of 3 sites during each season of sampling, except for late breeding season 2001, when 5 counts were completed at each of 3 sites. The total number of upland counts is 42. Detailed methods are described in Appendix 9A.

9.3.31 Fishpond surveys: Waterbirds have served as indicator species for conservation management in Deep Bay. They are also useful umbrella species for ecosystem characterisation and impact assessment in Deep Bay, based on their high trophic position, the concentration of wetlands and waterbirds in this part of the HKSAR and their identified international conservation importance. Bird surveys of fishponds in Outer Deep Bay were designed to provide data on distribution of this group during low and high tides. The objective is to quantify the relationship between low-tide bird feeding on the intertidal mudflat and bird loafing or roosting in nearby freshwater fishponds. Fishponds along the Outer Deep Bay coast were sampled in 3 clusters for purposes of bird survey, as shown in Figure 9.2: (1) Sheung Pak Nai, (2) Ngau Hom Sha and (3) Ngau Hom Shek. Cluster 1 is adjacent to the Pak Nai SSSI, a feeding site for terns and gulls and an area of recognised conservation importance for avifauna (Anon. 1995a). Each of the three clusters of ponds was sampled in Crosslinks2 studies. All birds at the two small fishponds nearest the proposed alignment at Ngau Hom Shek were sampled non-systematically and independent of the cluster sampling in December 2001 and April 2002 at the request of AFCD. Birds were identified to species and counted.

9.3.32 Five fishponds from each cluster were selected for sampling. Ponds were selected with an effort to achieve equality of sampled area in each cluster (to avoid biasing species richness comparisons between clusters). Birds using the fishponds in each cluster were counted and identified to species. Five surveys were completed during late breeding season (September 2001), three in each of autumn migration (November 2001), winter (January 2002), and spring migration (April 2002).

9.3.33 Breeding bird and egretry surveys: Breeding bird surveys were carried out in spring 2002 at the fish pond clusters discussed above from Ngau Hom Shek to Sheung Pak Nai; at upland point count sites at Ngau Hom Shek (see Figure 9.3); and at the Pak Nai and Ngau Hom Shek egretries. Egretries were counted 3 times in April-June 2002. Nest occupants were identified to species and number of nests of each species was counted. The breeding bird survey method selected is a modified version of Sharrock (1976). Birds were graded according to the behaviour observed, as follows:

· Possible breeding: Species with behaviour showing attempts to breed: territorial behaviour, such as intensive singing and calling for territories, or displaying or observed carrying nesting materials.
· Confirmed breeding: Species with behaviour or showing signs of breeding: nests found, or adults observed carrying food for juveniles, or adults observed feeding juveniles, or nestling or recent fledged juveniles observed.

9.3.34 Intertidal bird surveys: As noted above, waterbirds were identified as a useful indicator species for ecosystem characterisation and impact assessment in Deep Bay. Bird surveys of Outer Deep Bay mudflats were designed to provide data on feeding and distribution of this species group. Bird use of mudflat habitats on the south shore of Outer Deep Bay was surveyed to assess the importance of these habitats to birds, particularly species of conservation concern. Bird groups of particular interest were ardeids (herons and egrets), particularly species breeding at local egretries, and migratory waterbirds that pass through or over winter in Deep Bay, notably the Black-faced Spoonbill.

9.3.35 Four types of systematic survey were used to describe bird use of the intertidal zone. The first three methods (described in bullet points below) sampled fixed areas, while the fourth method (Section 9.3.36) aimed for Black-faced Spoonbill and attempted a total count:

· mudflat fixed-quadrat counts: All birds within three permanent 100 x 100 m quadrats on the mudflat were counted and identified. Permanent quadrats were established at Sheung Pak Nai, Ngau Hom Sha, and Ngau Hom Shek to match the epifauna sampling sites (see above, and Figure 9.2). Numbers of birds foraging on the mudflats were counted during low tide conditions when >100 m of mudflat were exposed.

· tideline 500 m belt quadrat counts: Counts covered a 500 x 10 m quadrat oriented parallel to and centred on tide lines. Counts were made on rising and falling tides when at least 100 m of mudflat were exposed. Quadrats were counted at Sheung Pak Nai, Ngau Hom Sha, and Ngau Hom Shek to match the epifauna sampling sites (see above, and Figure 9.2).

· mangrove point counts: Point count surveys were carried out for bird communities at mangroves at Sheung Pak Nai, Ngau Hom Sha, and Ngau Hom Shek to match the epifauna sampling sites (see above, and Figure 9.2). Ten minutes were spent counting birds seen or heard within 30 m from each point.

9.3.36 Black-faced Spoonbill: From November 2001 through May 2002 total counts were made of BFSs seen anywhere on the mudflat from Pak Nai northward to Lau Fau Shan. The mudflat was scanned from fixed observation points using binoculars and spotting scopes. Thirteen surveys were done between November 2001 and May 2002. When spoonbills were spotted, they were identified to species and counted.

9.3.37 At each of the mudflat and tideline systematic sampling locations five repetitions were counted in each of late breeding season, autumn, winter and spring sampling sessions. At mangrove systematic sampling locations five repetitions were counted in late breeding season, and 3 in each of autumn, winter and spring sampling sessions. The total number of counts at the 3 fixed area locations was 162.

· Late breeding season 2001: 5 repetitions x 3 habitats x 3 sites = 45 counts;
· Autumn 2001: 5 repetitions x 2 habitats x 3 sites + 3 repetitions x 1 habitat x 3 sites = 39 counts;
· Winter 2001-2: 5 repetitions x 2 habitats x 3 sites + 3 repetitions x 1 habitat x 3 sites = 39 counts; and
· Spring 2002: 5 repetitions x 2 habitats x 3 sites + 3 repetitions x 1 habitat x 3 sites = 39 counts.

Terrestrial Mammals

9.3.38 Study of terrestrial mammals covered the bridge landfall and proposed highway alignment. Small and medium sized mammals were surveyed non-systematically by searching for burrows, tracks, roadkills, and other signs. Mammal sampling sites were chosen to ensure coverage of habitats known from the consultants' experience to have high potential to support mammals of conservation interest. Field surveys were conducted from August 2001 through May 2002.

Coastal and Intertidal Habitats and Associated Invertebrate Fauna

9.3.39 Qualitative and quantitative surveys of intertidal habitats were conducted at sites selected based upon proposed alignments (i.e. Ngau Hom Shek, Ngau Hom Sha, and Sheung Pak Nai. See discussion of mudflat sampling, below). Surveys focused on mangroves, seagrass beds and mudflats due to the known ecological importance of these habitats. Surveys characterised and mapped coastal habitats and produced plant and animal species lists and estimates of abundance. Coastal habitats occurring within the Assessment Area for marine ecology were mapped based upon aerial photography supported by ground truthing.

9.3.40 Mudflat epifauna: Quantitative samplings and taxonomic analyses of mudflat epifauna were conducted to assess epifauna density. Epifauna abundance of Outer and Inner Deep Bay mudflats would be compared where comparable data on Inner Deep Bay are available from the literature.

9.3.41 The sampling programme was designed to characterise Outer Deep Bay mudflats, and to focus on mobile epifauna such as mudskippers and crabs that could be recorded visually at a distance sufficient to minimise observer interference. Sampling sites were fixed based on proposed alignments as at August 2001, epifauna abundance, ardeid use (favouring sites which appeared important during initial surveys), and accessibility.

9.3.42 Three sampling sites were chosen, one each at Ngau Hom Shek, Ngau Hom Sha, and Sheung Pak Nai. Sampling locations are shown in Figure 9.2. At each site 2 transects were placed 20 m and 40 m from the shore or edge of the mangrove. Along each transect, 5 m2 plots were marked out using bamboo sticks. A total of 2 plots covering 10 m in horizontal distance were thus sampled at each transect.

9.3.43 The observer used a spotting scope or binoculars to count and identify all visible mobile epifauna within each plot at a flooding or ebbing low tide (calculated from Tsim Bei Tsui tide station).

9.3.44 On some occasions, dogs or humans were present near the transects. A period of 15 minutes was allowed to elapse before sampling following any such disturbance of the mudflat area. The plots were monitored once in the wet season 2001 (September 2001) and once in the dry season 2001-2 (February 2002)).

9.3.45 Mudflat infauna: Mudflat infauna communities were sampled using core samples along 150 m transects perpendicular to the shore at Ngau Hom Shek, Ngau Hom Sha, and Sheung Pak Nai (Figure 9.2). Five stations were established along each transect at 10 m, 40 m, 70 m, 100 m, and 150 m distances from the seaward edge of the mangrove. At each station a quadrat measuring 0.5 m x 0.5 m was placed on the mudflat surface. Two core samples (10 cm dia./ 15 cm deep) were taken from within each quadrat. Each core sample was sieved using 1 mm and 0.5 mm mesh sieves. Collected organisms were then identified to the lowest taxon practicable. Species abundance and composition were compared with results from studies undertaken by Mouchel (1999) and in Inner Deep Bay for the Shenzhen River Regulation Project (Peking University undated).

9.3.46 Although there was no scientific support in the literature for more than one sample period for intertidal infauna, discussions with concerned departments resulted in a sampling regime to cover both "wet" and "dry" seasons. Infauna samplings were conducted on 26 September 2001 for wet season and 25 January 2002 for dry season.

9.3.47 Mangrove and seagrass survey: Qualitative surveys were conducted along the intertidal area from Sheung Pak Nai to Ngau Hom Shek to produce flora species lists and characterise mangroves, and to search for seagrass communities. Seagrasses in the assessment area displayed a growth form or distribution pattern that was typically patchy, which accounts for the term "seagrass bed", meaning a patch of mudflat occupied by seagrasses. This terminology would be used throughout this and all subsequent reports. Major seagrass beds were mapped during September and January 2001 and April 2002 and their areal extents were estimated. Habitats in the backshore zone within the study area had been altered by village houses, constructed seawalls, fishponds, cultivation, and light industry. Because of high levels of prior and existing disturbance, and consequent alteration of habitats, the backshore zone was not surveyed.

9.3.48 Mangrove and Seagrass Bed Fauna: Surveys were carried out to describe the fauna that inhabits the mangroves and seagrass beds within the assessment area, and to provide an index of species representation, abundance and density. Three quadrats measuring 0.5 x 0.5 m (0.25 m2) were arbitrarily located at each of three mangals. The locations of the three mangals covered Ngau Hom Shek, Ngau Hom Sha and Sheung Pak Nai, corresponding to the quadrat sampling points for bird surveys and the transects for infauna. All epifauna was identified to species and counted. Data were reported as species richness, species diversity, evenness, and abundance. Surveys for seagrass beds were conducted in the same methods as the mangrove survey.

9.3.49 Horseshoe crabs: Horseshoe crabs are an ancient and taxonomically isolated group (class Merostomata, sub-class Xiphosura) related to spiders, ticks and mites. They are important in biomedical applications where the blood of horseshoe crabs is the source of compounds used to screen for pathogens in medical facilities and on medical equipment. Three species occur in HKSAR waters: Tachypleus tridentatus, T. gigas and Carcinoscorpius rotundicauda. These represent all species known from the South China Sea, and three of four species known world-wide. Information on abundance of these species is limited, but Liang and Zhou (1987) note that in surveys in Beibu Bay, Guangxi/Guangdong, T. tridentatus made up 90% of the catch and the other two species together made up only 10%.

9.3.50 Horseshoe crabs, most commonly T. tridentatus, have been recorded in the HKSAR at Tap Shek Kok, Sha Chau, Tai Po and Peng Chau, though there are no recent records from any of these sites (Huang 1997). C. rotundicauda was recorded in 1997 from Ma Wan Chung, Lantau, at a site that would be lost to development of the Tung Chung New Town (ibid.). Horseshoe crabs have been seen in Port Shelter in recent years (Ecosystems Ltd., unpubl. data; Crow, and Molner pers. comm.), though at least some of these may have been animals released by Buddhists. The other areas where horseshoe crabs have been recorded in the HKSAR are on the shores of Outer Deep Bay and the waters around Black Point-Tap Shek Kok.

9.3.51 Two species of horseshoe crab, Tachypleus gigas and Tachypleus tridentatus, have been recorded from trawl surveys at Tap Shek Kok just south of Lung Kwu Tan, and the beaches at Lung Kwu Sheung Tan and Lung Kwu Tan have been identified as potential breeding sites for T. gigas (ERL 1992, ERM 1993, Planning Department 1993, SWK 1993). Juvenile horseshoe crabs are seen by fishermen in the intertidal zone from Sheung Pak Nai to Ngau Hom Shek, but adults are seldom seen.

9.3.52 The habitat requirements of horseshoe crabs world-wide have been poorly documented. In Deep Bay the preferred habitat was identified as sandy to muddy intertidal zones, which appear to provide habitat for juveniles. Non-systematic surveys for horseshoe crabs were conducted along the coast of Outer Deep Bay from Ngau Hom Shek to Sheung Pak Nai for the Crosslinks2 EIA (Mouchel 1999). On review of Mouchel (1999), and following interviews with Sheung Pak Nai fishermen we concluded the following:

· horseshoe crab adults and juveniles are present in the SWC assessment area;
· both adults and juveniles occur in the SWC assessment in very small numbers;
· the intertidal zone on the HKSAR side of Deep Bay (breeding habitat for horseshoe crabs) has undergone little change in the last 20 years; and
· horseshoe crabs occurred in the area in large numbers some 20 years ago, but probably have been extirpated by unsustainable harvest.

9.3.53 All three species of horseshoe crabs appear to be in population decline and are thought to be under severe pressure in the South China Sea, including HKSAR waters, due to habitat loss and overexploitation (Huang 1997). The conservation status of the three Indo-Pacific species is listed as "Data Deficient" by IUCN, indicating that existing knowledge is insufficient to determine whether they are threatened or endangered. Horseshoe crabs have been identified as species of potential conservation concern in the HKSAR.

9.3.54 Horseshoe crabs have important ecological roles that are virtually unknown in Hong Kong because of the local scarcity of horseshoe crabs. For example, some 425,000 to 1 million migrating birds rely on Delaware Bay (USA) forage resources to replenish fat reserves for continued northward migration. At least 11 species of migratory shorebirds rely on the eggs of horseshoe crabs in Delaware Bay as their primary food source. Juvenile and adult horseshoe crabs are the primary prey item of Loggerhead Sea Turtles, and maintenance of abundant adult horseshoe crabs is considered a potentially important component of overall conservation of Loggerhead Sea Turtles. Many fish also prey upon juvenile horseshoe crabs, indicating that healthy crab populations may be important to sustenance of viable fisheries (http://www.horseshoecrab.org/nh/eco.html).

9.3.55 Horseshoe crab populations have been severely depleted by overharvest, but have later recovered when protected. Delaware Bay horseshoe crabs were depleted by overharvest from the late 1800s through the early 1900s. Harvest pressure dropped in response to dwindling numbers of crabs, but market demand did not recover. Some 50 years later (by the 1970s) crab numbers had recovered to levels seen 100 years earlier (Kerlinger 1998).

9.3.56 As part of the mudflat epifauna survey in Deep Bay, horseshoe crab surveys were conducted monthly from September 2001 to February 2002. The survey method involved visual observation of crab trails around tidal pools in seagrass beds during low tide.

Subtidal Benthos

9.3.57 Subtidal benthic fauna was sampled using grab samples at 6 stations, with 3 replicate grabs per station (Figure 9.2). Samples were collected in October 2001, and again in winter 2001-2. Samples were sieved through 0.5 mm sieves, collected organisms were then preserved and stained using 70% formalin and rose bengal in preparation for identification to the lowest practicable taxon and counting.
Cetaceans

9.3.58 The cetacean species of potential concern in western Hong Kong waters is the resident Chinese White Dolphin (Indo-Pacific Hump-backed Dolphin) Sousa chinensis. Dolphins occur in three general locations in Hong Kong: North Lantau/Urmston Road, Lingdingyang, and Deep Bay.

9.3.59 North Lantau/Urmston Road has been surveyed extensively during studies for AFCD and for the Airport Authority. Jefferson (1998) reports and discusses results of systematic boat transect surveys for this area through spring 1998. This work generated a database that enables prediction of cetacean population size and distribution by season. The Crosslinks2 EIA reviewed available reports and consulted with team member Dr. T. Jefferson, to conclude that there was adequate information for prediction of Crosslinks2 impacts on cetaceans in North Lantau/Urmston Road. Accordingly, no further Crosslinks2 surveys were programmed for that area, and none are programmed under the SWC project.

9.3.60 The area denoted "Lingdingyang" for purposes of dolphin distribution covers the waters from Lantau Island west to the Guangdong Province coastline, and from Neilingding Island south to 22o 8' north latitude. Systematic boat transect surveys of this area were conducted for the Study on Tonggu Waterway through November 1998. Methodology used was the same as for the transect surveys reported in Jefferson (1998). That study indicated that the database is comparable to that for North Lantau/Urmston Road in terms of its utility for prediction of cetacean population size and distribution by season. Therefore, no further Crosslinks2 surveys were programmed for this area, and none are programmed under the SWC project.

9.3.61 Deep Bay is the third area of interest for dolphin distribution. Systematic transect surveys of Outer Deep Bay were conducted in July 1996-March 1998, and it was confirmed that Outer Deep Bay is used by S. chinensis (Jefferson 1998, 2000; Jefferson and Leatherwood 1998). Additional periodic boat and helicopter surveys of all of Deep Bay were carried out over a 12-month period for the Crosslinks2 Study. Although few data were collected during Crosslinks2 field surveys, dolphin observations were combined with findings of previous surveys using the same methodology (Jefferson 1998). The combined data set was reported in Jefferson (2000), which was reviewed to prepare a study plan for the SWC field surveys.

9.3.62 Jefferson (2000) demonstrated that dolphins were never recorded using the portion of Deep Bay to be crossed by the SWC bridge. In addition, SWC bridge construction methods were projected to require no blasting (underwater or underground) and no percussive piling other than sheet piling for cofferdam construction. The combination of (i) absence of dolphins in the assessment area and (ii) no requirement to use construction methods that could exert adverse impacts upon dolphins indicated that existing knowledge was adequate to assess impacts of the SWC project upon dolphins and to propose any needed mitigation measures. However, 5 additional dolphin surveys were carried out in the HKSAR side of Deep Bay to supplement and confirm existing knowledge. Aerial surveys 1 and 2 were carried out in November and December 2001 using a Government Flying Service (GFS) fixed-wing aircraft (Figure 9.4). Aerial surveys 3, 4, and 5 were carried out in January, February, and March 2002 using a GFS helicopter (Figure 9.5).

Additional bird-bridge survey

9.3.63 Because of the unique nature of the proposed Shenzhen Western Corridor and limitation of baseline information in Hong Kong, field surveys have expanded to locations outside the assessment area of the present EIA study and the boundaries of Hong Kong Special Administrative Region (HKSAR)(see Appendix 9C). This will enable a more thorough description/assessment on the potential impacts of the proposed bridge on flora and fauna, particularly birds foraging on inter-tidal mudflat.

9.4 Description of the Environment

Baseline Conditions

Introduction

9.4.1 Crosslinks2 studies provided a detailed characterisation of ecological baseline conditions in the assessment area and study area, as derived from literature review and field surveys (Mouchel 1999). This report reviews background information from the Crosslinks2 EIA and all field survey findings for the present study.

9.4.2 SWC field surveys began in August 2001 and continued through June 2002. Data gathered from literature and surveys conducted under this study are considered adequate for the following characterisation and identification of key issues and impact assessment. Detailed surveys results and data were shown in Appendix 9A of this report.

9.4.3 The ecological assessment area includes part of outer Deep Bay. Crosslinks2 (Mouchel 1999) has broken down the outer Deep Bay area for discussion purposes into four zones corresponding to four general habitat groupings:

· uplands;
· lowlands;
· coastal (backshore) /intertidal (tidal zone); and
· marine (Deep Bay WCZ).

9.4.4 This organisation is followed in this report to facilitate comparison between the present study and Crosslinks2 study.

9.4.5 Figure 9.6 shows the terrestrial and intertidal habitats within the study area and assessment area. The habitats are described according to the geographical locations as shown below.

Upland

9.4.6 No protected areas are located within the upland portion of the study area. Habitats recorded in the upland portion of the study area mainly included grassland/eroded hillside, shrubland, plantation and stream/channel (Figure 9.6). Upland habitats changed little since the Crosslinks2 Study. Most of the upland areas are at an early successional stage due to fire, erosion, poor soil condition and historic use of the Castle Peak range as a firing range. Annex A of Appendix 9A lists plant species recorded during SWC field surveys of all habitats in the study area.

9.4.7 Vegetation: No plant species of conservation concern was identified during the present field surveys. Plant species found in these upland areas are dominated by common, fire-tolerant, hardy species of low conservation interest apart from the presence of some rare or protected species such as Pitcher Plant Nepenthes mirabilis, which is protected under the Forestry Regulations. Pitcher Plants prefer open, wet and granitic sites. Weatherhead (undated) recorded Pitcher Plants along streams southwest of the SWC study area. A large population was recorded within the firing range above Pak Nai (Ng pers. comm. and Weatherhead undated).

9.4.8 Crosslinks2 field surveys recorded Pitcher Plants at two streams above Lung Tsai (Lung Kwu Tan), at a marsh at the southern end of Lung Kwu Sheung Tan, and above Nim Wan Road near the WENT Landfill. None was recorded near the areas from Sheung Pak Nai to Ngau Hom Shek. Certain wild orchid species are often associated with the Pitcher Plant (ibid.), although none was recorded during Crosslinks2 or SWC field surveys. All members of the orchid family (Orchidaceae) are protected under the Forestry Regulations.

9.4.9 Arup (2002) reported two ferns on burned hillslopes along the proposed Deep Bay Link (DBL) alignment, Brainea insignis and Pityrogramma tartarea. B. insignis is both rare and protected in the Mainland, and P. tartarea is considered rare in the Mainland. Both were found in an area on annually burned hillslope with numerous graves.

9.4.10 Stream: A number of small, steep streams drain the uplands of the Deep Bay catchment. Their upper reaches drain severely eroded and frequently burned uplands, and the streams are affected by erosion and sedimentation. Spate events during the wet season move large quantities of coarse, granular sediment into these streams. The effects of siltation and steepness of streams have apparently limited the abundance and diversity of aquatic fauna (sensu Greiner-Maunsell 1992 and Shea et al. 1995). No species that is rare or of conservation concern was found through literature review or has been recorded from field surveys of these streams.

9.4.11 Two small permanent streams drained the two catchments affected by the DBL project. These are referred to in this report as Ngau Hom Shek East Stream and Ngau Hom Shek West Stream (Figure 9.6). East Stream had been re-aligned and channelled upstream of Deep Bay Road, presumably at the time of fishpond construction on adjacent lands. Below Deep Bay Road East Stream served as a nullah carrying surface runoff and residential waste from adjacent village homes. West Stream remained in its natural bed above Deep Bay Road, but was channelled in a nullah below the road. Similar to East Stream, it carried surface runoff and residential waste from adjacent villages.

9.4.12 Avifauna: Dry upland habitats around Castle Peak appear to be of limited value for birds. All bird species normally nesting in upland habitats on or near the study area and recorded during the Hong Kong Breeding Bird Survey by HKBWS are of low conservation concern (Carey et al. 2001). Crosslinks2 bird surveys on hillsides yielded limited numbers of bird species, most or all of which were common in hillside habitats: e.g. Chinese Francolin, Red-vented Bulbul and Hwamei upslope of the Ngau Hom Shek-Ha Pak Nai coast. Species of conservation concern recorded in upland habitats in the West Stream valley above Ngau Hom Shek during SWC field surveys included Crested Serpent Eagle Spilornis cheela and Crested Goshawk Accipiter trivirgatus. Crested Goshawk was seen displaying near upland plantation at Ngau Hom Shek. The land-based portion of the SWC crossing may lie entirely within the territory of Crested Serpent Eagle(s). Crested Serpent Eagle is considered to be somewhat restricted in distribution and a local conservation concern (Fellowes et al. 2002). Crested Serpent Eagles and Crested Goshawks nest in woodlands, but there was no evidence of any large nest in any trees in the study area. Potentially suitable nesting habitat was concentrated southwest of the proposed alignment in plantation woodlands. All bird species recorded in the breeding bird survey in the SWC EIA are common and widespread in Hong Kong and are generally of low conservation concern. All wild birds are protected in the HKSAR under the Wild Animals Protection Ordinance.

9.4.13 Mammal: Some upland habitats in the Western New Territories are thought to be important to mammals, possibly due to the relatively low levels of human disturbance in these areas. A study of terrestrial habitats at Black Point found signs of Masked Palm Civet Paguma larvata, Small Indian Civet Viverricula indica and Chinese Pangolin Manis pentadactyla (ERL 1992). Javan Mongoose Herpestes javanicus has been recorded at the WENT Landfill site during ecological monitoring (Shea et al. 1995). All these species are protected under the Wild Animals Protection Ordinance. The relatively low levels of human disturbance in this area may be conducive to inhabitation by these species, which in many other parts of the HKSAR would come under more intense trapping pressure. The EIA of the Castle Peak Borrow Area suggested that the rocky terrain in this part of the Western New Territories provides shelter for a "diverse and abundant mammalian fauna" (Greiner Maunsell 1992). Arup (2002) reported Niviventer fulvescens, Rattus sikkimensis, and Rattus sp. from hillslope areas near the boundary of the DBL and SWC projects. All are common and widespread rodents in HKSAR.

Lowlands

Inner Deep Bay Lowlands

9.4.14 The ecology of the Inner Deep Bay area would not be directly affected by the proposed alignment. However, as Deep Bay was identified as an important ecological resource for consideration in the study, a review of the ecology of Inner Deep Bay agricultural/village habitats is provided here to determine whether there would be indirect impacts to Inner Deep Bay could result from bridge construction or operation.

9.4.15 The agricultural zone of Inner Deep Bay holds extensive areas of agriculture and village habitats, including the HKSAR's largest areas of fishponds. Historically, Inner Deep Bay was most likely dominated by mangrove wetlands. With the advent and spread of human populations, mangroves were converted to man-made wetlands (paddies, shrimp ponds and fish ponds) or to dry land (Irving and Morton 1988). Fishponds in the HKSAR's Deep Bay catchment, very limited in extent before World War II, began to replace paddies, shrimp ponds and other less profitable types of agriculture around the middle of the 20th century (ibid.). Fish ponds probably now account for the largest wetland area in the North-west New Territories excluding Deep Bay itself. Deep Bay fishpond area probably peaked during the 1970s or 1980s. In recent years, conversion of these ponds to other, more lucrative landuses, including open storage, has been increasing. Development projects including roads, railways, flood control schemes and housing developments have also accounted for a portion of pond loss.

9.4.16 Fishponds in Deep Bay, together with gei wai in the coastal zone, albeit man-made and often intensively managed habitat, currently perform some of the ecological functions of the natural wetlands that preceded them. Fishponds are less useful to most native species than the natural habitats that originally occupied this area, but they are now among the only significant areas of wetland remaining in the Deep Bay catchment, and are hence important for wetland-dependent species. Various studies have shown HKSAR fishponds to be important wetland habitat for wildlife, particularly birds (Melville et al. 1994, Chu 1995). A joint Mainland-HKSAR government report noted that "extensive conversion of fish ponds would increase local flooding risks and seriously disturb the ecological environment in the catchments" (HKGEPLG 1992).

9.4.17 Fishponds are of low botanical interest since pond bunds are dominated by common and widespread species. Frequent clearance of active pond bunds also precludes a complex plant community structure (see e.g. Anon. 1995b, Chu 1995). However, fishponds and pond bund vegetation constitute important habitats for many bird species. At least 136 species of birds (more than 25% of the species recorded in the HKSAR) have been recorded on the Deep Bay fishponds (Anon. 1995b). These records cover a broad taxonomic range (13 orders, or nearly half of the 27-29 orders in the world), and include many globally threatened species such as Imperial Eagle Aquila heliaca and Spoon-billed Sandpiper Eurynorhynchus pygmaeus.

9.4.18 Fishponds at the Mai Po Marshes Nature Reserve, together with gei wai in the coastal zone, are important foraging and breeding habitats for many bird species of international conservation concern (see e.g. Anon. 1995b). Fishponds in the lowland and gei wai in the coastal zone are the preferred feeding areas for the endangered species BFS (Peking University undated). The overwintering population of this species at Mai Po has represented 24% of the known world population of this species in some winters (Melville et al. 1997), 15.5% in January 2001, and 14% in January 2002 (Dahmer and Felley in prep.). The Pearl River Delta (Mai Po, Futian, and Macau) has supported on average 20% of the global winter BFS population since 1993 (ibid.). Fishponds are reported to be the most important foraging habitats for Little Egret (Wong 1991, Pearson 1993) and Chinese Pond Heron (Pearson 1993, Young 1994) during breeding season. Little Egret Egretta garzetta is the dominant species of the Mai Po Village Egretry (Young and Cha 1995, Carey 1999a, Wong et al. 2000, Kwok et al. 2001 and Wong and Kwok 2002).

9.4.19 Waterfowl in the Deep Bay area are counted regularly by members of The Hong Kong Bird Watching Society (HKBWS). The counts aim to quantify the wintering population and to monitor annual trends in waterfowl numbers. The first coordinated waterfowl count in Hong Kong was carried out on 14 January 1979, when Deep Bay and the adjacent marshes and fishponds were censused (Chalmers 1983). Subsequently, counts were undertaken in mid January from 1981 to 1991, monthly during winter (November to March) from 1992 to 1996 and monthly year-round beginning in November 1997. January and February counts are more stable than other months, and January always provides peak overall numbers. Figure 9.7 shows the temporal trend of January waterfowl counts in the Deep Bay area from 1979-1999. A steady increase in bird numbers was observed from 1979 (rs = 0.976, p < 0.05) until the peak count of 67,653 birds was recorded in 1996. Peak numbers between 1998 and 2002 fluctuated around 50,000. Since winter 1992-1993, 24 species have accounted for at least 92.8% of waterfowl in Deep Bay (e.g., Great Cormorant Phalacrocorax carbo, Little Egret Egretta garzetta, Common Teal Anas crecca, Eurasian Coot Fulica atra). Significant increases in abundance over the years have been observed for Great Cormorant and Tufted Duck Aythya fuligula. Deep Bay supported a significant proportion of the regional or global populations of some waterfowl species, e.g., 1% of regional population of each of Chinese Pond Heron and Little Egret, and 20-25% of global population of BFS (Carey and Young 1999).

9.4.20 Other terrestrial fauna: Fishponds are also important habitats for other wildlife species: mammals (11 species), reptiles (16 species), amphibians (8 species) and dragonflies (30 species, 28% of the total recorded in Hong Kong) have been recorded in ponds and pond bunds (Anon. 1995b). Reptiles recorded near fishponds include the uncommon species King Cobra Ophiophagus hannah and Banded Krait Bungarus fasciatus (WWF undated d, Karsen et al. 1986). Vegetation on fishpond bunds provides habitat and food plants for some uncommon butterfly species, including Long-banded Silverline Spindasis lohita, Formosan Swift Borbo cinnara and Silver Streak Blue Iraota timoleon, and rare species such as Dark Grass Blue Zizeeria karsandra (WWF undated c).

Outer Deep Bay Lowlands

9.4.21 No protected areas are located within the lowland portion of the study area. Lowland habitats within the study area were entirely modified by human activity. Habitat types included fishponds (active and abandoned), cultivation (active and abandoned), stream/channel, and urbanisation (roadside plantation, villages, and open storage areas). These habitats all had low plant diversity, simple habitat structure, and were of limited botanical interest. No plant species protected by local regulations and/or of conservation concern was recorded here.

9.4.22 The Agriculture, Fisheries & Conservation Department (AFCD) Categorization of Agricultural Land (AFD 1995) shows a continuous, fairly narrow coastal band of Grade A or B agricultural land (including fishponds) along the south shore of Deep Bay, from Mai Po to Nim Wan. Most ponds and agricultural land in this zone were in operation during 1998 (Mouchel 1999), but many ponds had been abandoned by September 2001. Many ponds had grassy bunds or bunds planted with orchard trees. Fishponds and agricultural land from Sheung Pak Nai to Ngau Hom Shek are ranked as Grade A in the AFCD categorization. This ranking is based on a range of criteria, including production-related factors, floodplain or buffer zone function and (in the case of fishponds) ecological value. AFCD revised its classification of Grade A and B land as "good", the definition of which does not address ecological value; however, baseline conditions in these areas have not changed appreciably since the grading criteria were revised.

9.4.23 Streams flowing through the agricultural/village zone on the south shore of Deep Bay are affected in varying degrees by water abstraction, domestic sewage and agricultural pollution. The lower courses of some streams have been channelised, particularly seaward of Deep Bay Road. East and West Streams through the SWC study area retained dense riparian vegetation. These streams drain the heavily eroded Castle Peak Range and are thus also subject to severe spate events and sediment deposition during the wet season, as shown by sand deposition in the channels and at stream mouths. Heavy rains in summer 2001 covered the beds and parts of the banks of streams on the south shore of Outer Deep Bay in a thick layer of coarse-grained sand. The mobility of the sand constrains the stability of the stream system, the growth of aquatic algae and consequently the diversity of stream fauna.

9.4.24 Fishponds on the south shore of Outer Deep Bay were first surveyed for birds in the Crosslinks2 EIA (Mouchel 1999). In that study 60 bird species were recorded foraging in fishponds and adjacent marshes (including mangroves) and mudflats at Ngau Hom Sha, Sheung Pak Nai, Pak Nai and Ha Pak Nai. SWC field surveys between September 2001 and May 2002 recorded 46 species at fishponds, 12 species on the intertidal mudflats, 12 species on the tideline, and 23 species in mangroves.

9.4.25 The stretch of coast from Nim Wan to Lau Fau Shan (NW/LFS) (6 km) has been surveyed 69 times between January 1979 and March 2002 (annual count in January between 1979 and 1992, annual counts during winter between 1993 and 1997, monthly count since November 1997), and provides the most detail information of waterbirds in Outer Deep Bay. A total of 67 species of waterfowl and raptors have been recorded (Carey 1998, 1999b, 2000a, 2000b, 2001, 2002). Red-billed Starling Sturnus sericeus and Collared Crow Corvus torquatus were also recorded in NW/LFS. Therefore, a total of 69 species were recorded between January 1979 and March 2002 in NW/LFS.

9.4.26 During the 69 waterfowl counts by HKBWS carried out between January 1979 and March 2002 in NW/LFS, only 28 BFSs were recorded (in 3 surveys). The Outer Deep Bay mudflats are not of great importance to Black-faced Spoonbills.

9.4.27 A summary of birds recorded in field surveys of Crosslinks2 from Ngau Hom Shek to Ha Pak Nai on the south shore of Outer Deep Bay is given in Mouchel (1999). The total number of bird species recorded by the end of the Crosslinks2 studies exceeded 100.

Ngau Hom Shek Lowlands

9.4.28 Lowland habitats at Ngau Hom Shek had changed little since the Crosslinks2 study. These habitats were highly modified by human disturbances. Habitat types included fishponds (active and abandoned), cultivation (active and abandoned), abandoned ponds, stream/channel, urbanised (roadside plantation, villages, and open storage areas) (Figure 9.6). These habitats all had low plant diversity, simple habitat structure, and were of limited botanical interest. No plant species protected by local regulations and/or of conservation concern was recorded here.

9.4.29 Fourteen species of butterflies were recorded, all on fish ponds and pond bunds, in the agricultural/village zone at Ngau Hom Shek during Crosslinks2 field studies. All are considered common or very common except the uncommon Small Yellow Eurema brigitta. SWC field surveys recorded 28 butterfly species between September 2001 and May 2002. All reported species except White Commodore Parasarpa dudu and Hong Kong Lacewing Cethosia biblis are considered common or fairly common. Nine species of dragonflies were recorded at Ngau Hom Shek during Crosslinks2 field surveys, mostly on fishponds. SWC field surveys recorded 13 dragonfly species in September 2001 and May 2002. All reported species are considered common or fairly common.

9.4.30 Three species of amphibian, i.e. Asian Common Toad Bufo melanostictus, Gunther's Frog Rana guentheri and Brown Tree Frog (Polypedates megacephalus), were recorded during SWC surveys between September 2001 and May 2002 (Appendix 9A). All were common and widespread in Hong Kong (Lau and Dudgeon 1999). Two species of amphibians were recorded at Ngau Hom Shek in Crosslinks2 studies: Chinese Bullfrog Rana tigrina and Gunther's Frog Rana guentheri. Gunther's Frog is very common on agricultural land (Karsen et al. 1986). Chinese Bullfrog is uncommon in Hong Kong due to habitat reduction, overexploitation as a food delicacy and widespread use of pesticides in agriculture (Karsen et al. 1986). It is a Class 2 protected animal in Mainland China (Hua and Yin 1993). Chinese Bullfrog, however, was not recorded during the field surveys for the present EIA. Arup (2002) documented the presence of additional amphibians at Ngau Hom Shek during field surveys of DBL in 2000-1. One of these, the Two-striped Grass Frog (Rana taipehensis) was found in an abandoned fish pond, and is considered to be restricted in local distribution, therefore of local conservation concern (Fellowes et al. 2002). The number of sites known to be occupied by the Two-striped Grass Frog in Hong Kong is increasing (see Dahmer et al. 2001), but new locations are relatively undisturbed, unmanaged ponds with abundant floating and emergent vegetation. Two-striped Grass Frog was also not recorded in the SWC surveys. Other amphibians reported in DBL surveys at Ngau Hom Shek but not recorded in the SWC surveys were Paddy Frog (Rana limnocharis), Asiatic Painted Frog (Kaloula pulchra), and Marbled Pygmy Frog (Microhyla pulchra).

9.4.31 All the natural streams within the study area have sandy substrates. Erosion from the nearby hill slopes provides abundant sandy material to the streams. The topography of the stream beds changes frequently, with the result that litter does not accumulate. There are also few stable hard surfaces to which flora or fauna could attach. Under these conditions aquatic organisms do not readily become established on stream beds, and no aquatic fauna other that guppies was recorded in any stream in the study area. This may have been due in part to the sampling schedule in the late wet season when high flow rates and volumes combined with a changing stream channel would have rendered the stream bed uninhabitable. Several guppies Poecilia reticulata were collected in the Ngau Hom Shek East Stream in September - October 2001. No other aquatic fauna was recorded. No aquatic fauna was recorded in February - March 2002 dry season survey.

9.4.32 Two species of reptiles were recorded during Crosslinks2 field surveys on fishpond bunds at Ngau Hom Shek: Chinese Skink Eumeces chinensis and Chinese Water Snake Enhydris chinensis. Both species are common in Hong Kong. Six additional reptile species were added during SWC surveys between September 2001 and May 2002 (Appendix 9A). Notable among them was the Burmese Python Python molurus, which is protected in HKSAR, listed in Mainland China as a Class 1 protected animal, and listed in Appendix II of CITES. It is also considered to be of potential regional conservation concern whose regional population is in drastic decline (Fellowes et al. 2002), and it is listed as lower risk/near threatened by IUCN World Conservation Union. A single juvenile Burmese Python was recovered after it had been killed on Deep Bay Road near Ngau Hom Sha (Appendix 9A). Two additional snakes, Indo-Chinese Rat Snake and Common Rat Snake, were documented at Ngau Hom Shek by Arup (2002). The Indo-Chinese Rat Snake was seen during SWC field studies as well. Both rat snakes are considered to be potential regional conservation concern whose global populations are in marked decline, and whose regional populations are in drastic decline (Fellowes et al. 2002).

9.4.33 Twenty-five bird species were recorded on fishponds and adjacent mangroves and mudflats at Ngau Hom Shek and 30 species at Ngau Hom Sha during Crosslinks2 surveys. Collectively, 37 species were recorded from these two areas. Records included birds observed foraging on the mudflat and mangroves near the fishponds. SWC field surveys between September 2001 and May 2002 recorded 33 species (Appendix 9A). Most recorded species are considered common and widespread, or local and common/uncommon, in the HKSAR; a number, such as Little Grebe, Yellow Bittern Ixobrychus sinensis, herons and egrets, are wetland-dependent.

9.4.34 Woodland Shrew (Crocidura attenuata), Sladen's Rat (Rattus sikkimensis) and unidentified rat (Rattus sp.) have been recorded to date near Ngau Hom Shek. Javan Mongoose Herpestes javanicus was recorded in agricultural/village habitat along Deep Bay road near Ngau Hom Sha and in upland habitats between September 2001 and May 2002. One dead Japanese Pipistrelle Pipistellus abramus and one dead Leschenault's Rousette Bat Rousettus leschenaulti, were recorded on fishpond bunds at Ngau Hom Sha between September 2001 and May 2002 (Appendix 9A). The Javan Mongoose (or Small Asian Mongoose) is considered to be somewhat restricted in geographic distribution and of local conservation concern (Fellowes et al. 2002). Based upon its rapid geographic spread throughout Hong Kong there is current speculation that the Javan Mongoose may be an introduced species (Corlett 2001). Leschenault's Rousette Bat is moderately restricted and in population decline. It is a frugivore and is also of local conservation concern (ibid.).

Sheung Pak Nai Lowlands

9.4.35 Lowland habitats at Sheung Pak Nai had changed little since the Crosslinks2 Study. These habitats were highly modified by human disturbances. Habitat types included fishponds (active and abandoned), cultivation (active and abandoned), stream/channel, urbanised (roadside plantation, villages, and open storage areas)(Figure 9.6). These habitats all had low plant diversity, simple habitat structure, and were of limited botanical interest. No plant species protected by local regulations and/or of conservation concern was recorded here.

9.4.36 The lower reaches of the Sheung Pak Nai stream, which empties into Outer Deep Bay within the Pak Nai SSSI, were characterised by a coarse sand bed and relatively low flows. The stream course was meandering and the banks were densely vegetated in the agricultural zone. The stream's lower reaches were heavily polluted with organic waste originating from a pig farm located on the stream bank. It is assumed that the sampling point lies upstream of the pig farm. Mullet (Mugil sp.) was the only fish species recorded in this stream during Crosslinks2 field surveys.

9.4.37 Twenty-seven species of butterflies were recorded at Sheung Pak Nai during Crosslinks2 field studies, including one rare species, the Danaid Eggfly Hypolimnas misippus, and 3 uncommon species: Purple Sapphire Heliophorus epicles, Small Yellow Eurema brigitta, and Swallowtail Papilio xuthus. Eight species of dragonflies were recorded at Sheung Pak Nai during Crosslinks2 field surveys. All are common or fairly common and widespread. In the SWC study area, 28 butterfly and 13 dragonfly species were recorded between September 2001 and May 2002 (Appendix 9A). All recorded species are common and widespread.

9.4.38 Seven species of reptiles were recorded in Crosslinks2 field surveys at Sheung Pak Nai: Chinese Skink, Reeves' Smooth Skink Scincella reevesii, Long-tailed Skink Mabuya longicaudata, Indo-Chinese Rat Snake Ptyas korros, Checkered Keelback Xenochrophis piscator, Red-necked Keelback Rhabdophis subminiatus and Bamboo Snake Trimeresurus albolabris. All are common in Hong Kong (Karsen et al. 1986). Two species of amphibians were recorded in Crosslinks2 study: Chinese Bullfrog and Gunther's Frog. SWC field surveys recorded no new amphibians or reptiles at Sheung Pak Nai.

9.4.39 Forty-four bird species were recorded foraging on fishponds and adjacent mangroves at Sheung Pak Nai during Crosslinks2 field surveys in January-September 1998. This was the highest number of bird species recorded at any of the 5 pond clusters surveyed in Crosslinks2 study. However, in the field surveys of SWC between September 2001 and May 2002, Sheung Pak Nai had the lowest species richness (26) of the 3 surveyed fishpond clusters. This may be related to the management of the fishponds by the fishermen. Only one of the surveyed fishponds was drained throughout the SWC studies, and bird use of fishponds is highest when water levels are reduced during draining for harvest of commercial fishes. Of the species recorded in 1998 for Crosslinks2, 27 were common and widespread, while 17 were more localised in distribution. One uncommon species was recorded, the Pied Bushchat Saxicola caprata.

Egretries

9.4.40 A small egretry at Ngau Hom Shek was first recorded during Crosslinks2 field surveys in June 1998 (Mouchel 1999). It was located in an open storage site adjacent to Deep Bay Road, and nests were built on bamboo (Figure 9.3). The maximum number of nesting pairs was 15 in 2000. The nesting population at Ngau Hom Shek egretry never made up more than 2% of the total nesting population over Hong Kong since its discovery in 1998. Only Little Egrets and Chinese Pond Herons have been recorded nesting. In 2002, there were 10 nesting pairs of ardeids recorded at Ngau Hom Shek egretry.

9.4.41 An egretry identified as the Pak Nai Egretry in Young and Cha (1995) was located in a clump of bamboo alongside abandoned fish ponds near Ha Pak Nai Village (Figure 9.3). Villagers reported that this egretry was established in 1988 or 1989 and that breeding numbers probably peaked around 1995. This egretry was first documented near the end of the 1995 breeding season, but no counts of nesting pairs were made that year (Young and Cha 1995). The Pak Nai egretry was also surveyed annually between 1998 and 2001 (Carey 1999a, Wong et al. 2000, Kwok et al. 2001, Wong and Kwok, in prep.). The egretry moved to a new location about 1.5 km NE of the former location in 2000, and this may have been a response to disturbance by villagers (Kwok et al. 2001). Four species were recorded nesting in this egretry between 1996 and 2002: Little Egret (numerically dominant), Great Egret Casmerodius albus, Chinese Pond Heron and Cattle Egret Bubulcus ibis. A maximum count of 58 breeding pairs was recorded at the egretry in 1998: 52 Little Egrets and 6 Chinese Pond Herons. Though the nesting population in Pak Nai egretry ranged from 3.0 to 6.1% of the Hong Kong total between 1998 and 2001, the population nesting at Pak Nai egretry, however, made up a significant proportion of the total in the Deep Bay area.

9.4.42 Both Little Egrets and Chinese Pond Herons are hunted intensively in the Pearl River Delta (Young and Cha 1995), and the local abundance of Chinese Pond Herons in Hong Kong is declining (Viney et al. 1996). A survey of the breeding populations of ardeids in colonies in the Pearl River Delta (Mainland) and Deep Bay (HKSAR) in June 1995 found that numbers of breeding pairs of these two species in the Pearl River Delta were very low compared to those in the HKSAR, despite the large area of wetlands available in the Delta (28,300 ha) (Young and Cha 1995). The nesting history of the Ngau Hom Shek and Pak Nai egretries is described in Appendix 9A. In 2001 Little Egrets occupied 274 nests in Hong Kong, of which 47 (17%) were found at Pak Nai (Kwok et al. 2001).

9.4.43 The ardeid species using the Pak Nai Egretry often forage in fishponds. Little Egrets and Chinese Pond Herons were frequently observed foraging in fishponds at Sheung Pak Nai, Pak Nai and Ha Pak Nai during Crosslinks2 surveys, with highest numbers during and immediately after the breeding season due to recruitment of juveniles.

9.4.44 Intertidal mudflats are another important foraging habitat for the species breeding at the Pak Nai egretry. Crosslinks2 field surveys showed that intertidal mudflats at Sheung Pak Nai, Pak Nai and Ha Pak Nai were more important feeding areas for breeding ardeids than the fishponds in these areas. This pattern was confirmed in SWC field surveys of the mudflat versus fishpond bird densities from Sheung Pak Nai to Ngau Hom Shek (Appendix 9A).

9.4.45 The uses of feeding habitats by nesting ardeids in the Pai Nai and Ngau Hom Shek egretries were studied using the "Flight-line Method". Intertidal mudflat is the most important habitat for Little Egrets in both egretries, and Chinese Pond Herons in Ngau Hom Shek egretry. Mangroves were also frequently used by Little Egrets and Chinese Pond Herons. The estimated mean flight distances of Little Egrets were similar at the two egretries (Pak Nai egretry: 476.4 ± 21.6 m; Ngau Hom Shek egretry: 407.8 ± 59.2 m).

9.4.46 Fishponds supported more bird species than did mudflats. Crosslinks2 studies documented 47 species feeding on mudflats from Sheung Pak Nai to Ha Pak Nai, while 63 species were recorded feeding at fishponds. Some birds were recorded only at fishponds (e.g. Little Grebe Tachybaptus ruficollis and Oriental Reed Warbler Acrocephalus orientalis) or only on mudflats (e.g. Curlew Numenius spp., Sanderling Calidris alba and Grey Plover Pluvialis squatarola). Some plant and other animal species were only found in one of these two types of habitats, or were present in both but at different levels of abundance. Mudflats and fish ponds thus perform different functions in the lowland/coastal ecosystem and cannot be directly compared except perhaps in terms of their use by a single strictly defined group of species, as here with ardeid birds.
Deep Bay North Shore Lowlands

9.4.47 Prior to the 1980s, extensive areas of agricultural land existed on the Mainland side of Deep Bay (HKGEPLG 1992). These areas have now been urbanised with the development of the Shenzhen Special Economic Zone (see background, Plate 16). Only small areas of natural lowland and coastal habitat now remain. These occur primarily inside the Neilingding Futian National Nature Reserve, where fish ponds and gei wai are still found in proximity to the mangroves and mudflats.

Coastal and Intertidal Zones

9.4.48 Natural coastal and intertidal habitats are found along the Ngau Hom Shek coastline (mudflats, limited seagrass beds, and mangroves) (Figure 9.6). Features of ecological importance in the coastal and intertidal zone within the assessment area are discussed site by site below. Discussion of coastal and intertidal habitats begins at Inner Deep Bay and continues along the south shore of Deep Bay to Sheung Pak Nai. Inner Deep Bay is discussed first due to its acknowledged ecological and conservation importance.

Inner Deep Bay Coastal and Intertidal Zones

9.4.49 Inner Deep Bay holds the largest area of mangroves in the HKSAR, the sixth largest mangrove area in China, and one of the largest areas of reedbed in southern China. It is an internationally important site for migratory and overwintering waterfowl, which feed on the mudflats, shallows, gei wai and fishponds of Inner Deep Bay. Inner Deep Bay supports in the neighbourhood of 60,000 waterfowl each winter. Numbers of wintering birds in Deep Bay increased steadily from 13,000 in 1979 to a maximum of 68,000 in January 1996 (Melville et al. 1997). Maximum winter waterfowl counts have decreased since the high in early 1996.

9.4.50 The intertidal zone in Inner Deep Bay is an important foraging area for many resident and migrant birds. The mudflats are known to provide critical forage resources to long-distance migrants that stop at Mai Po to restore fat reserves for continued migration or to spend the winter. Inner Deep Bay supports significant percentages of the world populations of several waterbird species in season, including rare and endangered species (Peking University undated, Melville et al. 1997). This includes >1% of the world population of Asiatic Dowitcher Limnodromus semipalmatus, 10% of Nordmann's Greenshank Tringa guttifer, and >1% of the flyway population of species including Lesser Sand Plover Charadrius mongolus and Grey Plover (Peking University undated, Melville et al. 1997). Deep Bay also supports the largest overwintering population of Cormorants in East Asia (Peking University undated). Large flocks (counted in thousands of individuals) of Red-billed Starling Sturnus sericeus are also recorded in Deep Bay areas annually (Hong Kong Bird Reports). Inner Deep Bay supports over 300 bird species and an abundant mammal and reptilian fauna. It is the only place in Hong Kong where the Slender Sea Snake Hydrophis gracilis has been recorded (Karsen et al. 1986). It is also the type locality for over 20 species of invertebrates new to science (Melville et al. 1997).

9.4.51 The international conservation importance of the Mai Po and Inner Deep Bay area has been acknowledged by the Mainland and the HKSAR for several decades. In the HKSAR, the area of mangroves and gei wai known as Mai Po Marshes was designated an SSSI in 1976 for its botanical and ornithological value (Anon. 1995a). Nearby, the Mai Po Village SSSI was established in 1979 to protect an egretry (ibid.). The Inner Deep Bay SSSI, established in 1986 to protect the Inner Deep Bay mudflats, lies adjacent to the Mai Po mangroves at their seaward edge. The Inner Deep Bay SSSI is the HKSAR's largest, at 2,300 ha (ibid.). The Tsim Bei Tsui SSSI was established in 1986 to protect mangrove communities. The Tsim Bei Tsui Egretry SSSI was established in 1989 to protect an egretry. The locations of these SSSIs are shown in Figure 9.9. In 1994 the Town Planning Board established two Buffer Zones around Mai Po and the Inner Deep Bay mudflats, with the goal of prohibiting development incompatible with conservation of the area's natural value (TPB 1994).

9.4.52 The Mai Po Marshes Nature Reserve is approximately 380 ha in area, and consists of mangrove forest, gei wai and fish ponds. The Mai Po Marshes mangrove, at 85 ha, is the largest remaining in Deep Bay (Tam and Wong 1997). This mangrove community is dominated by Kandelia candel, Aegiceras corniculatum, Avicennia marina and Acanthus ilicifolius, with Bruguiera gymnorrhiza and Excoecaria agallocha as secondary species (Irving and Morton 1988). The mangrove is considered well-established and expanding, the main body of it having remained mostly undisturbed since the 1940s (Peking University undated). The extent of the mangrove has varied over time since aerial photographic records began in 1945; its current tendency is toward seaward expansion at a rate of 3.47 m/yr (ibid.).

9.4.53 Mangroves provide important habitats, including nesting sites, for birds such as ardeids and rails. Locally rare birds including Styan's Grasshopper Warbler Locustella lanceolata, Collared Kingfisher Todirhamphus chloris and Middendorff's Grasshopper Warbler Locustella ochotensis have also been recorded in the Mai Po mangroves (Diskin 1997). Mangroves at Mai Po provide habitat for the Mangrove Snake Enhydris bennetti, which is found only in mangroves on the south-east coast of China and is known from only a few sites in the HKSAR (Karsen et al. 1986, GLA 1998). The largest population throughout its global range is probably found in Hong Kong (Zhao 1998). The Mai Po mangroves also provide habitat for mammals such as otters and civets.

9.4.54 The mudflat at Mai Po is an extremely important habitat for many waterbird species during the migration season. This area has been shown to be an important foraging habitat for the ducks and waders at Mai Po (Peking University undated). The number of ducks feeding on the mudflat on a single day, 13 February 1995, exceeded 12,000. In addition, this mudflat is the preferred foraging habitat of Saunders' Gull Larus saundersi, the most endangered gull in the world and a Bonn Convention Appendix I species (ibid.). Deep Bay in winter supports 5% of the world population of this species (ibid.). Saunders' Gulls feed mostly at low tide, catching small crabs and worms (WWF undated e). Another Bonn Convention Appendix I species, the Dalmatian Pelican Pelecanus crispus, also feeds on the mudflat at Mai Po. Deep Bay supports at least 20% of the regional population of Dalmatian Pelican (Carey and Young 1999).

9.4.55 The gei wai is built in the intertidal zone with sluice gate access to the bay. The sluice gate is opened during high tide to wash in juvenile shrimp, and shrimp are harvested by opening the sluice gates at low tide to drain the pond while placing a narrow-mesh net in the gate to capture the mature shrimp (Irving and Morton 1988). Mangrove communities inside the gei wai are retained when the pond is excavated, and provide shelter and food for the maturing shrimp. Gei wai shrimp culture was formerly widespread in Hong Kong, but it is now practised in the HKSAR only at the Mai Po Marshes Nature Reserve, where the Penaeid shrimp Metapenaeus ensis is raised in some 16 gei wai covering 175 ha.

9.4.56 Gei wai, together with fish ponds in the lowland zone, at the Mai Po Marshes Nature Reserve are important foraging and breeding habitats for many bird species of international importance (see e.g. Anon. 1995b). Gei wai and fish ponds are the preferred feeding areas for the endangered BFS (Peking University undated). The overwintering population of this species at Mai Po has represented 24% of the known world population of this species in some winters (Melville et al. 1997). Diving ducks such as Shelduck and dabbling ducks such as Shoveler are known to forage in gei wai (WWF undated a, b). Mangroves in gei wai provide breeding sites for colonially nesting herons and egrets. Night Herons, Chinese Pond Herons, Little Egrets and Great Egrets bred in the mangroves at the landward end of gei wai 12 in Mai Po in 1993 and 1994 (Young and Cha 1995). Reedbeds in gei wai provide habitat for bitterns, buntings, reed warblers and Penduline Tits (Diskin 1997) and are also important insect habitats. A total of 389 insect morphospecies from 79 families in 11 orders were identified in a detailed study from December 1990 to April 1992 (Reels 1994). Of these 389 morphospecies, 252 were represented by fewer than 10 individuals in samples (ibid.).

9.4.57 Over 330 bird species have been recorded at Mai Po (Chen et al. 1997). Winter Waterfowl Counts at the Mai Po Marshes Nature Reserve between November and March each year regularly count several thousand waders of about 45 species, including the Asiatic Dowitcher Limnodromus semipalmatus, Nordmann's Greenshank Tringa guttifer and Spoon-billed Sandpiper Eurynorhynchus pygmaeus (Diskin 1997).

9.4.58 A large area including the Mai Po Marshes, roughly half of the Inner Deep Bay SSSI, and coastal and estuarine habitats to the south and east of these was designated as the HKSAR's first Ramsar Site. The location of the Mai Po and Inner Deep Bay Ramsar Site is shown in Figure 9.9. The HKSAR Government has obligations to protect the integrity of the Ramsar Site, as well as other important wetlands within its boundaries, under the Ramsar Convention, and a Management Plan for the Ramsar Site has recently been completed.

9.4.59 In the Mainland the conservation importance of Inner Deep Bay has been recognised primarily through designation of Futian as part of the Neilingding-Futian National Level Nature Reserve. The Nature Reserve lies on the Deep Bay Coast north of the Shenzhen River mouth. Its location is shown in Figure 9.9. The reserve stretches for up to 11 km along the north shore of Inner Deep Bay, and includes mudflats, mangroves, fish ponds and gei wai. The reserve is 304 ha in area including the intertidal mudflats. The mudflats at Futian are 1-1.6 km in width and have a high organic carbon content. 86 species of benthos have been recorded here, dominated by polychaetes, crustaceans and molluscs (CGEDC 1996a, Peking University undated). The Peking University study recorded mostly species able to tolerate high organic loadings and anoxic or near-anoxic conditions. Approximately 70 ha of the reserve at Futian is covered by mangroves. The mangrove runs in a narrow band along the shore, 200 m in width at its widest point (Peking University undated, CGEDC 1996a). The major mangrove species represented are similar to those found at Mai Po: Kandelia candel, Aegiceras corniculatum, Avicennia marina, Bruguiera gymnorrhiza and Acanthus ilicifolius (ibid.).

9.4.60 186 species of birds have been recorded at Futian, 23 of which are considered rare or endangered (CGEDC 1996a). Over 10,000 birds of over 100 species overwinter there, and winter counts of 40,000 have been recorded (Chen et al. 1997). Species recorded here include the following Class II China protected birds: Dalmatian Pelican, Saunders' Gull, Swinhoe's Egret Egretta eulophotes and BFS, and many raptor species (Hua and Yin 1993). Other endangered and rare wetland species recorded at Futian are the Oriental White Stork Ciconia boyciana, White Ibis Threskiornis melanocephalus, European Spoonbill Platalea leucorodia, Bewick's Swan Cygnus columbianus and Nordmann's Greenshank. However, numbers of both wintering and breeding bird species at the Futian reserve have declined in recent years, mainly due to the destruction of mangroves, gei wai and fish ponds for urban development which has destroyed half of the reserve's mangrove area (Chen et al. 1997). The effect of this habitat loss on birds has been marked; the number of resident bird species declined by 40% and the number of breeding species declined by 70% between 1994 and 1995 (ibid.).

9.4.61 Tsim Bei Tsui is a mangrove and mudflat site at the south-western edge of the Mai Po Marshes and Inner Deep Bay Ramsar Site. The mudflats and mangroves at Tsim Bei Tsui are important sites for waterbirds and have been included in the Ramsar Site. Two SSSIs have been designated at Tsim Bei Tsui. The Tsim Bei Tsui SSSI was designated on the north side of the point in 1985 to protect a mangrove community. This mangrove is large (35.48 ha) and dominated by Kandelia candel (Tam and Wong 1997). Tam and Wong (1997) classified this stand as Category 3 in their ranking: "important stands and worth to conserve". The Tsim Bei Tsui Egretry, slightly inland and to the south, was designated in 1989 to protect an egretry (Anon. 1995a). The locations of these SSSIs are shown in Figure 9.9.

9.4.62 Mudskippers are harvested from the intertidal mudflats of Inner and Outer Deep Bay. Other mangrove-associated fauna harvested in Deep Bay are the Mangrove Crab Scylla serrata and the large goboid fish Bostrichthys sinensis. Collection of mudskippers and other mudflat fauna may have implications for the abundance of the prey base for wading birds, but this issue has not been fully evaluated (Young and Melville 1993).

Outer Deep Bay Coastal and Intertidal Zones

9.4.63 Mudflat: A band of intertidal mudflats follows the south shore of Outer Deep Bay from Tsim Bei Tsui out to the mouth of the Tai Shui Hang Stream near Ha Pak Nai. This coastal zone, some 11 km in length, includes various intertidal habitats which are discussed individually below. Most of the coastline consists of medium to coarse grained sandy beach higher on the beach, grading into mudflats below the tideline. The substrate of these mudflats is generally not as fine-textured as that in Inner Deep Bay. The coastline is natural in almost all places, in marked contrast to the north shore of Deep Bay, where natural shores are almost wholly gone except for an estimated 1-1.5 km of mudflats and mangroves within the nature reserve at Futian.

9.4.64 Mangroves occur on the south shore of Outer Deep Bay at Ngau Hom Shek, Sheung Pak Nai, Pak Nai and Ha Pak Nai. Some have colonised naturally, but most have been planted by villagers (see Figure 9.11). These mangrove communities are all dominated by K. candel. Tam and Wong (1997) described these areas collectively as "the Sheung Pak Nai mangrove" and classified them as "important stands and worth to conserve". Survey findings for each mangrove area in Outer Deep Bay are reported separately below.

9.4.65 Seagrass: Crosslinks2 field surveys found beds of the seagrass Halophila beccarii on the south shore of Deep Bay, primarily on the seaward side of mangrove communities and also near stream mouths. H. beccarii is widely distributed along the coasts of the South China Sea and has been recorded from numerous Southeast Asian countries. It generally occurs in the lower regions of the eulittoral zone. It prefers sheltered, estuarine-influenced areas where salinity levels are low (Hodgkiss and Morton 1978). H. beccarii had been considered of doubtful occurrence in Hong Kong (SWIMS 1994), but recent records have confirmed its occurrence at Black Point, at Lantau's Tai Ho Wan, and in Starling Inlet in addition to Deep Bay (Wong 1998, Frew and Yau pers. comm.). The Outer Deep Bay beds represent the largest known area for this species in HKSAR.

9.4.66 Epifauna - Crab: Field surveys were conducted to estimate crab density in the intertidal zone in Outer Deep Bay and results were compared to available data for Inner Deep Bay. Studies conducted for the Shenzhen River Regulation Project EIA (Peking University undated) reported crab densities on the Mai Po mudflat as 1.46/m2 in April, 0.39/m2 in August and 1.15/m2 in September 1994. In Crosslinks2 field surveys, average crab density across all Outer Deep Bay sampling sites was 2.13/m2 in April, 0.6/m2 in August and 2.96/m2 in September 1998. Based on this comparison, crab densities appear to be markedly higher on Outer Deep Bay than Inner Deep Bay mudflats. Seasonal trends in crab density were similar in Outer and Inner Deep Bay, with lower densities in August followed by a considerable rise in September. The Shenzhen River study focused on Macrophthalmus and Grapsid crabs, and estimated crab density based on burrow density. The Crosslinks2 study focused on Uca spp. and Macrophthalmus as observed visually. Given that the two studies used different target species and methodologies, results of the two studies may not be comparable. In the present study Crosslinks2 methods were used to investigate crab densities at two potential landing sites, i.e. Ngau Hom Shek and Sheung Pak Nai, and one control site between them at Ngau Hom Sha. Sampling in September 2001 showed no crabs or mudskippers within the quadrats. The quadrats were re-sampled in October 2001. At Sheung Pak Nai the crab density at the quadrats 40 m from the coastline (4.5/m2) was higher than that at the quadrats 20 m from the coastline (1.0/m2). A similar pattern was observed at the control site at Ngau Hom Sha where crab density was 4.4/m2 at 40 m from the shore, and 1.7/m2 at 20 m from the shore. In Ngau Hom Shek the two sites of the former quadrats were entirely occupied by recently established oyster beds, and no crabs or mudskippers were seen on the surrounding mudflat areas where oyster cultches had not been installed. Thus the attempt to sample crab densities nearer the shoreline than the original 20m and 40m distances was interrupted by recent human activities. A dry season survey was conducted in February 2002. Crabs and mudskippers re-appeared on the mudflats at Ngau Hom Shek. It was considered that epifauna had been recovered from the influences of oyster cultch installation in 2001, though disturbance from oyster cultch maintenance by oyster farmers still continued. The crab density (3.0 - 3.3 No./m2) was similar with those recorded in Ngau Hom Sha and Sheung Pak Nai at the same sampling.

9.4.67 Epifauna - Mudskipper abundance across all mudflat sites sampled in Outer Deep Bay appeared to be slightly lower than in Inner Deep Bay, based on literature review and interim sampling results. Young and Melville (1993) estimated the density of mudskippers in Inner Deep Bay at 5/m2 during spring. Average mudskipper density at Crosslinks2 sampling sites in Outer Deep Bay in 1998 was 2.7/m2, ranging from 1.6/m2 in April to 4.2/m2 in September. Crosslinks2 study methods were used to investigate the mudskipper density at two potential bridge landing sites at Ngau Hom Shek and Sheung Pak Nai, and one control site between them at Ngau Hom Sha. In September 2001 no mudskippers were recorded within the quadrats. Quadrats were re-sampled in October 2001. At Sheung Pak Nai the mudskipper density 20 m from the coastline (3.9/m2) was higher than that 40 m from the coastline (3.1/m2). Similar mudskipper densities were recorded at the control site at Ngau Hom Sha where density was 3.5/m2 at 20 m from the shore, and 2.1/m2 at 40 m from the shore. At Ngau Hom Shek the two quadrat locations were both occupied by recently established oyster beds. No mudskippers were found in areas occupied by oyster cultches or on the surrounding mudflats that were unoccupied by oyster cultches. Thus the attempt to sample mudskipper density nearer the shore than the original 20 m and 40 m distances was interrupted by recent human activities. The oyster beds had a severe negative impact upon mudskipper densities, which in turn appeared to cause sharp declines in bird numbers. A dry season survey was conducted in February 2002. Crabs and mudskippers re-appeared on the mudflats at Ngau Hom Shek. It was considered that epifauna had been recovered from the influences of oyster cultch installation in 2001, though disturbance from oyster cultch maintenance by oyster farmers still continued. The crab density (3.0 - 3.3 No./m2) was similar with those recorded in Ngau Hom Sha and Sheung Pak Nai at the same sampling. The mudskipper density recorded (1.6 - 1.7 No./m2), however, was still much lower than those of the other two sites (2.7 No./m2 In Ngau Hom Sha and 3.5 No./m2 in Sheung Pak Nai).

9.4.68 Small-scale localised mudskipper harvesting is common on the mudflats of Outer Deep Bay, particularly at Sheung Pak Nai and Ha Pak Nai. Mudskippers appear to be used for feed at fish farms, based on observations of fishermen setting mudskipper traps at various locations along the south Deep Bay coast and grinding and mashing captured mudskippers (Periophthalmus cantonensis and Boleophthalmus boddaerti) for fish pond cultivation. They are also sold to the Mainland for human consumption. Other mangrove-associated fauna harvested in Deep Bay are the Mangrove Crab Scylla serrata and the large goboid fish Bostrichthys sinensis.

9.4.69 Mudflat infauna: Wet season mudflat infauna core sampling was completed in September 2001, while dry season sampling was conducted on 25 Jan. 2002. 1282 individuals of benthic infauna from 29 species were recorded. Detailed results were presented in Appendix 9A. The species composition, biomass, species richness and diversity were provided.

9.4.70 Annelids, bivalves and crustaceans were the dominant faunal groups in the specimens found. No rare species was found in the samples. Polychaete Neanthes glandicincta was the most common and abundant infauna in the samples. It was present in most intertidal infaunal samples and its total number was 649, representing over 50 % of the total number of organisms recorded (1282). The highest number in one sample was over 120. Polychaete Heteromastus filiformis was the second abundant infauna, reach the number of 182.

9.4.71 Black-faced Spoonbills: BFS is classified as endangered by IUCN (BirdLife International 2000), and is a Class II Protected Animal in China. Wang (1998) recommended upgrading the listing to Class I Protected Animal in China. The species is found only in East Asia, where it is threatened by habitat loss and degradation, and land/water pollution (BirdLife International 2000). Very little is known of BFS nesting biology. The locations of wintering sites are better known than the breeding sites.

9.4.72 More than 75% of the global population winters on two sites, one at the Mai Po Inner Deep Bay Ramsar Site in Hong Kong, and the second at the Tsengwen River estuary in Taiwan (WWFHK 2001a). The proportion of the global population supported by three sites in the Pearl River estuary has averaged 20% since 1993 (Dahmer and Felley in prep.). A peak count of 164 birds was recorded in Mai Po Inner Deep Bay Ramsar Site in November 1999 (WWFHK 2001b). All reported BFS annual census results for Hong Kong plus Shenzhen and Macau are shown in Figure 9.10. The HKSAR-Shenzhen counts show an increasing trend. Both locations showed sharp increases in 2001. Notably, the sharp increase in the Macau population occurred after completion of the "Co-Tai" reclamation that links the former islands of Coloane and Taipa, and simultaneous with completion of the Lotus Bridge that links the Co-Tai reclamation with Mainland China at Zhuhai. Prior to 2001 the BFS population at Macau had not exceeded 13 birds (Leung V., pers. comm.). The sharp increase in the Macau BFS population is most likely attributable to the unintended provision of a man-made freshwater wetland roosting habitat near a man-made mudflat foraging area. These two habitats are separated by the Lotus Bridge, over which BFS fly daily enroute between foraging and roosting habitats.

9.4.73 The two most important aspects of wintering ecology of BFS in Deep Bay are feeding and roosting. An attempt to build a nest was reported in Mai Po on 27 December 1994, but no bird was subsequently seen in the "nest" (Chalmers 1998). Studies on the feeding and roosting ecology of BFS in Deep Bay started in the mid 1990's.

9.4.74 The main feeding habitats of BFS in Deep Bay are inter-tidal mudflat, drained fishponds and drained gei wais (WWFHK 2001c). In this EIA study, Black-faced Spoonbills were only recorded feeding on tidelines within the Study Area. BFS usually feed in gei wais with water levels between 41 and 80 mm, and no spoonbill was seen feeding when water depth exceeded 200 mm (Kwok 1993, WWFHK 1999). Studies on feeding ecology showed that feeding rates were highest in drained gei wais, and lowest on inter-tidal mudflats. However, inter-tidal mudflats were considered to be more important as feeding habitats because rich food items in drained fishponds or gei wais are only available for the initial few days after draining (WWFHK 1999). BFS feed both during daytime and at night, but feeding success was higher at night (Leader 1998). The most common prey of BFS included shrimps Macrobrachium nipponense and Exopalaemon styliferus, and mosquito fishes Gambusia affinis (Leader 1998, WWFHK 2001c). Analyses of stomach contents of dead birds collected outside Hong Kong showed that small fishes are potentially the most common prey (Hseuh et al. 1993 in WWFHK 2001c).

9.4.75 BFS usually roost inside Mai Po Marshes Nature Reserve, possibly due to the low levels of human disturbance there (WWFHK 2001c). BFSs roost on gei wai bunds where vegetation is short or completely lacking, trees on gei wai bunds and short mangrove trees (ibid.). They also roost on the mud surface in drained gei wais, and inter-tidal mudflats in Mai Po and Tsim Bei Tsui, when the tide is low.

9.4.76 The uses of inter-tidal mudflat between Tsim Bei Tsui and Ha Pak Nai by Black-faced Spoonbills were studied between November 1999 and March 2000 (total 23 surveys) (WWF 2001a). Most Black-faced Spoonbills were recorded on inter-tidal mudflat in Tsim Bei Tsui (66%) (Yu, Y. T., unpubl. data). Proportions of total birds counted in Sheung Pak Nai, Pak Nai and Ha Pak Nai were 6.2%, 2.9% and 0.2% respectively (Yu, Y. T., unpubli. data). The use of mudflat in Outer Deep Bay by Black-faced Spoonbills is not considered high.

9.4.77 SWC field studies during winter 2001-2 confirmed that small flocks of BFS used the outer Deep Bay intertidal zone for foraging. BFS were recorded from Ngau Hom Shek to Pak Nai in group sizes ranging from 1 to 17 birds. The maximum count was made at Pak Nai (17 birds on 7 January 2002). Ngau Hom Shek had the highest average count per survey (0.92 bird per survey), but Ngau Hom Sha and Sheung Pak Nai also supported small numbers of BFS (0.46 bird per survey). BFS were observed moving along the coastline and feeding in shallow waters near the tide line.

9.4.78 Other waterbirds: Bird communities of intertidal habitats along the stretch of 6km coastlines between Nim Wan and Lau Fau Shan (=NW/LFS in Waterfowl Count Reports) were surveyed 69 times between January 1979 and March 2002 in the Waterfowl Count organized by The Hong Kong Bird Watching Society (HKBWS) (Agriculture and Fisheries Department undated, Carey 1998, 1999b, 2000, 2001, 2002). A total of 67 species of waterfowl and raptors, together with Red-billed Starling Sturnus sericeus and Collared Crow Corvus torquatus, were recorded in NW/LFS. In terms of individual number, Black-headed Gull Larus ridbundus was the dominant species (30% of total birds). Cormorants Phalacrocorax carbo and ducks (e.g., Wigeon Anas penelope) were also abundant. However, these species were all winter visitors. Species constantly recorded and abundant throughout the year were Little Egrets Egretta garzetta and Chinese Pond Herons Ardeola bacchus. Six species of global/region conservation concern were recorded between January 1979 and March 2002. They were Dalmatian Pelican Pelecanus crispus (Class 2 protected animal of Mainland China), Black-faced Spoonbill Platalea minor (Class 2 protected animal of Mainland China, listed as endangered by IUCN World Conservation Union), Baikal Teal Anas Formosa (listed as vulnerable by IUCN World Conservation Union), Black-eared Kite Milvus lineatus, Buzzard Buteo buteo and Osprey Pandion haliaetus. The latter three raptor species are listed in Appendix 2 of CITES and are Class 2 protected animal of Mainland China. Since the observations were not presented by locations, the exact locations where these species were recorded could not be determined. All these 6 species except Black-eared Kite were only recorded in winter. Black-eared Kites were recorded throughout the year. This species is widespread in Hong Kong and can be found in many types of habitats.

9.4.79 Since the waterfowl count frequency had been expanded to monthly in November 1997, peak counts of birds were always recorded in winter (November - March) (Figure 9.8). The results showed that bird abundance on inter-tidal mudflats in winter (November - March) is on average 3 times higher than that during non-winter seasons. The mean bird abundance during winter (November to March) and outside winter (April to October) in Nim Wan /Lau Fau Shan between November 1997 and March 2002 was 368 birds and 109 birds respectively.

9.4.80 Both mean bird abundance and species richness were higher during winter (November to March) than those outside winter (April to October) in NW/LFS between January 1979 and March 2002. Of the 69 species recorded, 46 are winter visitor, 21 are resident species, one is summer visitor (Yellow Bittern Ixobrychus sinensis) and one is non-breeding visitor which mostly seen in winter (Intermediate Egret Mesophoyx intermedia).

9.4.81 Among the 21 resident species, one-third of them are ardeids. Bird community outside winter was dominated by four ardeid species, i.e. Little Egret, Great Egret, Grey Heron and Chinese Pond Heron, which made up 80.5% of total birds (1929 out of 2397 birds) between May 1998 and October 2001. These species feed on inter-tidal mudflat, fishponds, streams and cultivated lands. Nine resident species - Little Grebe Tachybaptus ruficollis, Night Heron Nycticorax nycticorax, Striated Heron Butorides striatus, Cattle Egret Bubulcus ibis, Yellow Nib Duck Anas poecilorhyncha, Banded Rail Gallirallus striatus, White-breasted Waterhen Amaurornis phoenicurus, Moorhen Gallinula chloropus and Coot Fulica atra - feed mostly in fishponds, cultivated lands, mangroves or edges of mangroves. These habitats will not be significantly affected by the project. Other resident species included four kingfisher species, Little Ringed Plover Charadrius dubius, Black-eared Kite Milvus lineatus, Osprey Pandion haliaetus and Collared Crow Corvus torquatus. Only Ospreys are more dependent on coastal area as feeding habitats.

9.4.82 Summer visitors constitute the least proportion of avifauna of Hong Kong in terms of species richness. Of the 448 species recorded to date, only 17 species are classified as summer visitors (3.8%). Summer visitors of Hong Kong (e.g., Black Baza Aviceda leuphotes, Large Hawk Cuckoo Cuculus sparverioides, Savannah Nightjar Caprimulgus affinis) are mostly inhabitants of terrestrial habitats (e.g., grassland, shrubland, forests). Two species, the Roseate Tern Sterna dougallii and Bridled Tern S. anaethetus, are maritime. Yellow Bittern Ixobrychus sinensis is the only species likely to occur in inter-tidal habitats in the Study Area. Even so, this species is mainly confined to mangroves. Only one Yellow Bittern has been recorded in coastal habitats between Nim Wan and Lau Fau Shan during the 69 waterfowl counts between January 1979 and March 2002. Waterfowl Counts in Outer Deep Bay were carried out monthly since November 1997. No bird species was only recorded in summer (June to August) but not in other times of the year. Two migrants - Green Sandpiper Tringa ochropus and Common Sandpiper Actitis hypoleucos - were regularly recorded outside winter. However, these two species are generally disturbance tolerant and also feed in other wetland habitats in the study area (e.g., fishponds).

Ngau Hom Shek Coastal and Intertidal Zones

9.4.83 The coastal mudflat from Ngau Hom Sha to Ngau Hom Shek was dominated by mangrove plantations. The mangroves Kandelia candel were planted in rows to protect the fishponds behind the shore. Plantings typically extended about 20-50 m seaward from the back shore (typically a constructed seawall). The oldest plantings had reached a height of over 3 m. Since the Crosslinks2 study, new plantings were also observed on the shoreward side of the old plantations. Mangrove and mangrove associate species recorded at Sheung Pak Nai during field studies are listed in Annex A of Appendix 9A.

9.4.84 The Crosslinks2 study documented 2.5 ha of beds of seagrass Halophila beccarii from Sheung Pak Nai extending southwest to Ha Pak Nai while none was recorded in the current SWC assessment area. During the current surveys about 0.6-0.9 ha of seagrass were recorded spreading along the entire coastline from Sheung Pak Nai to Ngau Hom Shek within the assessment area. Because seagrasses are relatively quick to exploit suitable habitats, discovery of this species northeast of Sheung Pak Nai during the current study was not unexpected.

Ngau Hom Sha & Sheung Pak Nai Coastal and Intertidal Zones

9.4.85 The intertidal mudflat at Sheung Pak Nai was dominated by coarse grained sand, which became coarser in texture towards the mudflat-beach interface. The beach was approximately 6 m wide. The Crosslinks2 EIA recorded occasional ocypodid crab burrows toward the backshore. Mangrove and mangrove associate species recorded at Sheung Pak Nai during field studies are listed in Annex A of Appendix 9A. One tree species of restricted distribution, Thespesia populnea, was recorded at the coastal area at Sheung Pak Nai near the fringe of the study area (Figure 9.6). Both mature fruiting trees and young saplings were seen, indicating a regenerating population.

9.4.86 One partial carapace of a horseshoe crab was found along the Sheung Pak Nai shore during September 2001, as reported in Appendix 9A. One juvenile Tachypleus tridentatus was found on the Ngau Hom Sha shore in October 2001. No horseshoe crab was recorded from November 2001 through January 2002. A second juvenile Tachypleus tridentatus was found on the Ngau Hom Sha shore in April 2001 (Appendix 9A; Figure 9.6 and 9.11).

9.4.87 Pak Nai SSSI lies outside the boundary of SWC assessment area. This intertidal SSSI was designated in 1980 due to its importance as a high-tide roost for gulls and terns (Anon. 1995a).
Marine - Deep Bay Lingdingyang, and Urmston Road

9.4.88 Deep Bay is a deeply indented (approximately 17 km), shallow bay on the east side of the Pearl River Estuary. It is fed by the Shenzhen River, Yuen Long River and Dasha River, and heavily influenced by the Pearl River. Deep Bay has an area of 115 km2 and an average depth of 2.9 m, depth being greater in the outer bay (CGEDC 1996b). Outer Deep Bay has a predominantly sandy substrate, while the substrate in Inner Deep Bay is almost exclusively mud (MHA 1987). One main channel runs from the mouth of the Shenzhen River across the mudflats roughly west toward Outer Deep Bay. Other, shallower channels also cross the mudflats of Inner Deep Bay. Salinity levels in the bay fluctuate seasonally, with highest levels between November and February and lowest levels during the wet season (Peking University undated). The shallowness of the bay prevents stratification of water layers during the wet season (HKGEPLG 1992).

9.4.89 Deep Bay is sheltered and relatively slow-flushing (CGEDC 1996b). Pollutant inputs require an estimated average of 15 days to leave the bay. The bay is polluted with domestic, industrial and agricultural waste, and is also subject to heavy sedimentation from both its own catchment and the Pearl River. Wastewater discharge and runoff from Shenzhen into the Bay averages 169 million m3 per year, of which half is industrial wastewater and almost one-third domestic sewage (CGEDC 1996b). Most of this discharge enters via the Shenzhen River and other watercourses at the head of Inner Deep Bay. The HKSAR's two innermost water quality sampling stations in Deep Bay have regularly failed to meet the HKSAR Government's Water Quality Objective (WQO) for dissolved oxygen since monitoring began in 1986 (Mouchel 1997). The three innermost Deep Bay stations have failed to meet the WQO for unionised ammonia since 1986 (EPD 1997). All Deep Bay stations have failed to meet the WQO for total inorganic nitrogen since 1986, though levels are higher in Outer Deep Bay than Inner Deep Bay. E. coli levels have been increasing at most stations throughout the bay in the past 10 years, as have depth-averaged total nitrogen and total phosphorus. Sampling stations in the Inner Bay also fail to meet Mainland standards for dissolved oxygen and chemical oxygen demand (CGEDC 1996b). Ambient variation in suspended solid levels in Deep Bay is extremely high, particularly in Inner Deep Bay (e.g. ranging from 7.6 to 91.0 mg/L at station DM3; EPD 1997). Water quality in the Outer Bay is generally better, presumably due to the greater distance from pollution sources in the Inner Bay and the influence of marine waters. Water quality monitoring stations in Inner Deep Bay show higher inorganic nutrient (total nitrogen and phosphorus), E. coli and faecal coliform levels than those in Outer Deep Bay (EPD 1997).

9.4.90 An increase in pollution from the Shenzhen River and other local feeders has been documented in recent decades (Leung et al. 1975, ERL 1988a, Young and Melville 1995). While livestock waste discharges from the HKSAR are believed to be declining due to the Government's Livestock Waste Control Scheme, other sources, notably domestic and industrial sewage discharges from the Mainland, have been increasing. Human population levels are increasing on both sides of the boundary, though both the HKSAR and Shenzhen governments are making efforts to keep pace by installing or upgrading sewage treatment systems (HKGEPLG 1992). One side effect of organic water pollution is that it provides a major source of the nutrients that drive the Deep Bay estuarine food web (Peking University undated, S. Y. Lee unpubl. data). Human and livestock waste appear to be important fuels to Deep Bay ecology, indirectly supporting fisheries and oyster culture resources in the Bay as well as mudflat fauna and waterbirds.

9.4.91 Levels of nitrogen, phosphorous and other nutrients in Deep Bay, particularly Inner Deep Bay, are high and could be expected to result in eutrophication. That this has not led to algal brooms may be due to various factors, e.g. low light penetration into Deep Bay waters due to high turbidity, high loads of certain toxic metals, or grazing by shellfish (Mouchel 1997).

9.4.92 Lee (1993) recorded 81 species of non-terrestrial invertebrates at the Mai Po Marshes Nature Reserve, of which 13 were previously undescribed species. Most of these species inhabit the mangrove mudflats, where they serve as important food sources for migrating and resident birds. Studies on the Mai Po mudflats recorded 78 morphospecies of benthic infauna, not all of which could be identified down to the species level (Peking University undated). Faunal biomass at Mai Po was dominated by polychaetes and was observed to decline during summer, possibly a regular effect of seasonal changes in temperature, salinity and water quality.

9.4.93 Studies have recorded 128 species of phytoplankton in Deep Bay, in a community dominated by Coscinodiscus spp. (HKGEPLG 1992). Twenty-three species of zooplankton, including 11 species of copepods and 7 species of medusa, have been recorded in Deep Bay. Species richness and diversity for both phytoplankton and zooplankton are higher in Outer Deep Bay than Inner Deep Bay (ibid.).

9.4.94 Deep Bay benthic fauna follows a classic polluted-estuary ecotone (Pearson and Rosenberg 1978). Species diversity is highest in Outer Deep Bay, and drops with distance to the mouth of the Shenzhen River and other polluted feeders of Deep Bay. The Inner Deep Bay fauna shows higher abundance and biomass than that of Outer Deep Bay (MHA 1987). Dominant groups of benthic fauna in Deep Bay include Crustacea, Gastropoda, Lamellibranchia and Polychaeta (HKGEPLG 1992). The fauna can be divided into four distribution patterns depending on substrate type, salinity and oxygenation of ambient waters (MHA 1987, ERL 1993). The two zones most relevant to the SWC project are a zone in the middle reaches of Deep Bay, where echinoderms and mussels occur at high densities, and a zone in soft substrate areas of the bay, dominated by echinoderms including sea urchins and brittle stars.

9.4.95 Qiu (1999) recorded 28 taxa of polychaete worms in Deep Bay, Neilingding, and Urmston Road, 15 of which were found in Deep Bay. Of the three sites the polychaete community in Deep Bay was found to be the highest in species richness and species diversity. Polychaetes were also more abundant in Deep Bay than in Neilingding or Urmston Road.

9.4.96 Leung (1999) recorded 11 species of penaeid prawns in Deep Bay, Neilingding, and Urmston Road, 7 of which were found in Deep Bay. Dominant species were Parapenaeopsis hungerfordi and Metapenaeus affinis. The penaeid prawn community in Deep Bay was the lowest in species diversity of the three areas, but prawns were most abundant in Deep Bay. The Deep Bay and Neilingding prawn communities were considered to be moderately disturbed by anthropogenic factors, and Urmston Road was considered to be severely disturbed.

9.4.97 Lee and Leung (1999) recorded a total of 14 brachyuran crab species in Deep Bay and the Pearl River estuary, 2 of which occurred in inner Deep Bay (Charybdis japonica and Scylla serrata), and 4 of which occurred in outer Deep Bay (Dorippe callida, Charybdis variegata, Portunus pelagicus, and P. sanguinolentus). The western waters of HKSAR were found to be lower in species richness than the eastern waters. This was attributed to the more saline, oceanic condition of eastern HKSAR waters as opposed to the estuarine nature of the western waters.

9.4.98 Up to 26 Great Crested Grebes were recorded using marine waters off Ngau Hom Shek in winter 2000-1 by Arup (2002). The species was not recorded during SWC field surveys in winter 2001-2. Great Crested Grebe is considered a regional conservation concern whose population is somewhat concentrated locally (Fellowes et al. 2002). Great Cormorants were also recorded offshore from Ngau Hom Shek in winter 2001-2 (near Lau Fau Shan) in large flocks numbering over 1000 birds. Great Cormorants are considered a potential regional concern whose population is regionally concentrated (ibid.).

9.4.99 Dolphins: The Indo-Pacific Hump-backed Dolphin ("Chinese White Dolphin") has been recorded in Deep Bay (Jefferson 1998). The only systematic surveys for this species in Deep Bay prior to the present study were conducted by the Crosslinks2 EIA and Ocean Park Conservation Foundation (ibid.). To supplement the data available from those sources, systematic transect surveys for dolphins were carried out in Deep Bay as part of the SWC study. The survey coverage was the same as that for Crosslinks2 studies. Surveys 1 and 2 took place in November and December 2001 using a fixed-wing aircraft contracted from Government Flying Service (GFS) (Figure 9.4). Surveys 3, 4 and 5 took place in January, February and March 2002 respectively using a helicopter also from GFS (Figure 9.5).

9.4.100 Results of Crosslinks2 surveys in Deep Bay agreed with studies conducted in 1996-98, in that dolphins were observed to occur mostly at the mouth of the bay, but were occasionally sighted as far into the bay as a line drawn between the east tip of Shekou and Sheung Pak Nai. Dolphins have not been recorded north of that line, thus were never recorded in the vicinity of the proposed S-curve bridge alignment. Outer Deep Bay at Ngau Hom Shek was not used by dolphins.

9.4.101 SWC surveys recorded sightings of 0, 1, and 5 dolphins during surveys 1, 2, and 3 respectively. Five, 5 and 9 dolphin sightings were recorded in the January 2002, February 2002 and March 2002 surveys respectively. All dolphins were seen at the mouth of Deep Bay near Black Point (Figure 9.12). These results confirm the results cited above from Crosslinks2 studies, namely that Deep Bay near Ngau Hom Shek is not dolphin habitat. Of the other 15 species of marine mammals that occur in Hong Kong but have not been recorded near Sheung Pak Nai, none was observed during any dolphin survey conducted in Deep Bay to date.

9.4.102 Several factors combine to give the local population(s) of Sousa chinensis a high degree of conservation concern. First, cetaceans have a relatively low reproductive rate, rendering populations slow to recover from losses. Second, estuary-dwelling cetaceans typically come into close conflict with human activities due to the dense human populations and high levels of human activity at river mouths. Estuarine cetaceans are prone to accidental bycatch in fisheries, vessel collisions, and effects of pollution. All these factors have been shown to operate on the local dolphin population (Parsons 1997). Sousa chinensis is a Class I protected species in the Mainland where planning for a nature reserve for dolphins is underway (Wang 1998). In the HKSAR, it is protected from capture or direct harm under the Wild Animals Protection Ordinance.

9.4.103 Subtidal benthos: Wet season subtidal infauna grab sampling was initially programmed to coincide with the site investigation survey. Due to logistical complications it was reprogrammed for mid-October 2001 and independent of the site investigation survey. A total of 18 0.1 m2 grab samples were collected (three replicates from each of the two sampling stations established in the subtidal zone along each of the three transects, see Figure 9.1). The sampling locations were identified using a satellite position system. Sieving and sorting followed methods for intertidal infauna. Dry season sampling was conducted on 25 January 2002. The species composition, biomass, species richness and diversity were provided in Appendix 9A. Identification of benthos have also make reference to the results of recent AFCD benthic surveys in Deep Bay.

9.4.104 A total of 618 individuals from 29 species were collected in the two samplings. The species composition, biomass, species richness and diversity were provided Annex W of Appendix A. Grab sampling was carried out to establish benthic baseline conditions and to assess the importance of the existing benthic communities close to and outside the alignment. Six stations were selected, including two on the alignment and four outside.

9.4.105 No rare species was found in the samples. Polychaete and phoronida were the two main component fauna in the grab samples collected. Organisms of these two taxa constituted about 90 % of all organisms recorded. The number of species in each sample was low. None of them exceed 10. Diversity index (H') of all six sites in wet and dry seasons ranged from o.76 to 1.56. In terms of species number and diversity index, the benthic fauna was not diverse. The density of organisms was also low, given that only 618 organisms were found in 36 samples in two samplings.

Summary - Key Resources

9.4.106 Key ecological resources have been identified in the study area through literature review and field survey. These include designated nature conservation protection areas (see Figure 9.9), and habitats and species which are protected, rare, vulnerable to human disturbance or otherwise of conservation interest. Key sites, habitats and species have been identified based on the criteria set forth in Annex 8, Tables 1, 2 and 3 of the EIAO-TM, in conjunction with local and international knowledge. The following tables list sites, habitats and species of conservation concern which have been identified in the study area. This presentation focuses on areas that could be affected by SWC bridge construction or operation.

9.4.107 Habitats found within the study area and assessment area were evaluated in terms of ecological importance, using the criteria set forth in Annex 8, Table 2 of the EIAO-TM. Ecological importance of the area as a whole is summarised in Tables 9.4.1a and 9.4.1b. Ecological values of each terrestrial and freshwater habitat type are evaluated separately in Tables 9.4.2 to 9.4.11. Intertidal and marine habitats are evaluated in Table 9.4.12. Location and distribution of the habitats are shown on the habitat map (Figure 9.6).

Table 9.4.1a Evaluation of Ecological Importance of the Area as a Whole

9.4.108 Of 8 habitat types considered to be important in HKSAR (EIAO-TM), 6 occur in varying degrees of "naturalness" on the SWC study area. Two additional habitat types considered to be of documented importance, i.e. communal nesting site (egretry) and fishponds, also occurred.

Sites of conservation concern9.4.109 Sites of conservation concern and relevant to the current SWC project include mangroves, mudflats, seagrass beds close to the alignment of the bridge.

Table 9.4.13 Summary of Habitat Evaluation

Species of conservation concern

9.4.110 The conservation status of the flora and fauna species of conservation concern is evaluated based on Table 3 of Annex 8 of the EIAO-TM.
9.4.111 The seagrass Halophila beccarii and Thespesia populnea are considered of conservation concern. Their conservation status is shown in Table 9.4.14 below.

Table 9.4.14 Conservation Status of Flora Species of Conservation Concern

9.4.112 A total of 78 bird species were recorded within the study area during systematic and non-systematic surveys (Appendix 9A). Peregrine Falcon Falco peregrinus was recorded in upland habitats in October 2001, and White-cheeked Starling Sturnus cineraceus was recorded on fishpond bunds in Ngau Hom Shek in January 2002. Peregrine Falcon is locally rare and is of local conservation concern, while White-cheeked Starling is of potential regional concern (Fellowes et al. 2002). A flock of 2-3,000 Cormorants Phalacrocorax carbo was seen on the sea between Ngau Hom Shek and Lau Fau Shan in December 2001. This represents some 45.5-68.3% of the number of Cormorants in Deep Bay area in December 2001 (4391 birds) (Carey 2002). Fauna species of conservation concern are summarized in Table 9.4.15 overleaf. Level of conservation concern follows Fellowes et al. (2002). The protection status of these species is also listed.

9.4.113 In summary, the ecological baseline study has covered all items highlighted in the Study Brief of SWC EIA, i.e. intertidal mudflat; mangrove; seagrass bed; inter-tidal and sub-tidal benthic faunal communities; egretries; Horseshoe crab (Tachypleus tridentatus); avifauna, in particular, Black-faced Spoonbill (Platalea minor); and Chinese White Dolphin (Sousa chinensis).

9.4.114 During the field surveys for the present project, two plant species including the seagrass Halophila beccarii and Thespesia populnea, one marine invertebrate (Horseshoe crab\ Tachypleus tridentatus), one reptile, 25 species of birds, two species of mammals, including Chinese White Dolphin, were recorded within the assessment area and are of conservation concern.

9.4.115 Among those species of conservation concern recorded, however, only the seagrass Halophila beccarii, horseshoe crabs, and 10 waterbird species including Black-faced Spoonbill (all boldfaced in Tables 9.4.14 & 15) are considered that their presence in the assessment area is relevant to the SWC project. The potential impacts upon these species are discussed in the following section of this report.

Table 9.4.15 Conservation Status of Fauna Species of Conservation Concern

* All birds in Hong Kong are protected under the Wild Animals Protection Ordinance (Cap. 170).

**Percentages shown in this column taken from Carey et al. 2001

Level of concern: LC = local concern, PRC = potential regional concern, RC = regional concern, GC = global concern (Fellowes et al,. 2002)

Rarity and Distribution in Hong Kong follows: Reels (1996), Karsen et al. (1998), BirdLife International (2000), Carey et al. (2001)

9.5 Assessment Methodology

9.5.1 The significance of ecological impacts is evaluated based primarily on the criteria set forth in Table 1, Annex 8 of the EIAO-TM:

· habitat quality;
· species affected;
· size/abundance of habitats/organisms affected;
· duration of impacts;
· reversibility of impacts; and
· magnitude of environmental changes.

9.5.2 Determination of "habitat quality", "species affected" and "size/abundance of habitats/organisms affected" will make reference to the previous sections of habitat and species evaluation. "duration of impacts" and "reversibility of impacts" are closely related the nature of the impacts. Usually construction disturbance such as noise will be regarded as short-termed and reversible, while the occupation of the space by the development itself is a permanent and irreversible impact. "magnitude of environmental changes" is determined by the scale of the projects, i.e. the extent of the works area and/or the degree of changes of the ambient environment. The availability of the same kind of habitat in Hong Kong, or individuals of the same species, will also be considered.

9.5.3 Impacts are generally ranked as "minor", "moderate" or "severe", although in a few cases a ranking of "insignificant" (less than "minor") may be given. The ranking of a given impact will vary based on the criteria listed above. The major factors giving rise to a ranking (e.g. an impact affecting species of high conservation concern giving rise to a ranking of "severe") are explained in the text. Wherever possible, significance of impacts is quantified to allow ready appreciation of relative significance. Quantification is straightforward for certain types of impact, particularly habitat loss (usually measured in hectares). If the habitat type affected is rare in Hong Kong, or the loss caused by the proposed project is in large scale and may influence the total carrying capacity of such habitat type in Hong Kong for dependent species, impacts will be considered "severe". On the other hand, if the loss or impact is confined to a small fraction of the habitat in Hong Kong, especially those located away from the core area, the impact will be considered minor or insignificant. Quantification of other types of ecological impact requires the application of professional judgment and value judgments, as noted in paragraph 5.3.1, Annex 16 of the EIAO-TM. Such judgments may not be amenable to quantification.

9.5.4 Impacts are assessed in the absence of mitigation. Mitigation is proposed in Section 9.8 to reduce significant impacts to acceptable levels. For the purposes of this report "Significant" is used to refer to impacts requiring mitigation and is applied to "minor", "moderate" and "severe" impacts, while "insignificant impact" is not requiring mitigation.

9.5.5 Sensitive receivers of impacts are defined for this report as species of conservation concern whose local, regional, or global populations would be expected to show the effects of reduced survivorship or productivity caused by the project. This implies that project-induced losses are predicted to exceed the range of fluctuation attributable to natural population variation.

9.6 Identification of Environmental Impacts

9.6.1 This section of the report identifies the potential ecological impacts of the SWC.

9.6.2 The impacts identified include the following:

Table 9.6.1 Summary of Potential Impacts Identified

9.6.3 Impact assessment is based on the EIAO-TM (particularly Annexes 8 and 16).

9.7 Prediction and Evaluation of Environmental Impacts

9.7.1 The ecological impacts of the SWC are first assessed in isolation. Then the cumulative effects of the SWC with other projects are discussed.

9.7.2 The gazette boundary between the DBL and SWC projects would be at the high-tide line. Therefore, the SWC impact assessment will concentrate in subtidal and intertidal zone. Terrestrial impacts associated with the SWC have been considered and initial assessment was provided in the alignment selection process (see Section 4 of this report). Detail assessment on all land-based construction impacts and mitigation would be addressed by the DBL project. This assessment would, however, provide general outlines of the DBL impacts and mitigation proposals because the SWC works and EIA assessment limits overlapped those of the DBL project.

9.7.3 Before the ecological impact assessment for the current bridge option landing at Ngau Hom Shek, it should be noted that for the Shenzhen Western Corridor, its location in Deep Bay, its option and landing point were all advantageous for avoiding and minimising the ecological impacts. Details are given in Section 9.8 below.

9.7.4 Description of the project construction: The SWC bridge would cross Deep Bay from Dongjiaotou, Shekou to land at Ngau Hom Shek. The bridge would be approximately 5.2 km long and would require an estimated 70 pier sites, mostly in paired form (at 75 m pier spacing), 40 of which would be in HKSAR waters. Of the 40 HKSAR piers, approximately 8 would be in the intertidal zone (assuming the mean lower low water mark of +0.4 m defines the low tide line, i.e. 600m from the coastline), and approximately 32 would be subtidal. At most pier locations, two piers would be built to support the two separate bridge decks. The construction phase impact area at each typical paired-pier location is calculated below and affected areas are listed in Table 9.7.1.

· total cofferdam area within which pile boring and formation, and pile cap formation will take place = 10 x 10 m x 2 cofferdams = 200 m2 for typical sites;
· plus total area between coffer dams at each pair of piers = 7 x 10 m = 70 m2;
· disturbance perimeter of 5 m around above 10 x 27 m area = 470 m2; and
· total affected area at each pair of piers = 200 + 70 + 470 m2 = 740 m2 or 0.074 ha.

9.7.5 The assumption of a 5 m buffer around the cofferdams and intervening space was made to account for vessel access and equipment operation during piling and pier construction.

9.7.6 The most landward pair of piers would be located within the mangrove plantation in Ngau Hom Shek. In addition to the mangrove trees in the area required by the pier site, we also assume the mangrove trees, mostly between the coastline and the pier site, would be affected during the construction of cofferdams, due to the transport of instruments for the first pier site on the land workfront. So the total affected mangrove area on HKSAR side would be 50 x 50 m = 0.25 ha, though only 0.074 ha would be physically occupied by the pier site.

9.7.7 A temporary steel bridge would be constructed alongside part of the alignment to enable access to work sites by workers and equipment. For the purpose of this assessment we assumed the temporary bridge would be approximately 1.8 km in length and require 25 of paired-piers, and the size of its piers would be the same as the cofferdam of the SWC bridge piers, i.e. 10m x 10m. Based upon this conservative calculation, the temporary bridge would cause another 0.5 ha temporary marine habitat loss (0.16 ha in intertidal zone & 0.34 ha in subtidal zone). The temporary bridge would be in place for a short time period of the 28 months construction project, and would be removed before the permanent bridge deck is in place.

9.7.8 Some details of bridge design and construction would be refined in the on-going SWC design and construction assignment. However, the following assumptions were made for purposes of impact assessment based upon previous sections in this report.

9.7.9 We assumed the preferred piling method to be rotary piling, and that underwater blasting would not be required for pier construction. Piers would be formed on free standing piles with pile caps below the mud surface. The estimated duration of construction works at each pair of piers is 7.5 weeks. The bridge deck would be precast off-site, then barged and lifted into place. Construction-phase dredging would be required only within the cofferdams for pier construction. Operation-phase dredging to restore baseline tidal exchange rates to maintain sediment flux regimes for water quality (Mouchel 1998) would not be required. Ship protection would be provided by additional piles upstream and downstream of bridge piles at navigation channels. Construction and operation phase impacts of the bridge are discussed below.
Construction Phase Impacts

9.7.10 Temporary habitat loss - Marine: This discussion excludes reclamation at the Shekou landing point, which lies outside the scope of this assessment. Construction of bridge piers across Deep Bay would destroy and fragment muddy seabed habitat in Deep Bay, possibly affecting marine organisms, primarily subtidal benthos. Benthic epifauna and infauna communities would be affected at pier sites due to temporary loss of seabed habitat. An estimated 2.368 ha of subtidal seabed in HKSAR would be temporarily lost to bridge pier construction (see Table 9.7.1). An additional 0.34 ha of subtidal seabed would be lost due to construction of the temporary bridge. The total HKSAR project would temporarily affect 2.708 ha of subtidal seabed. This accounts for some 0.024 percent of the total 11,500 ha of Deep Bay seabed. It should also be noted that the "2.708 ha" subtidal seabed loss is only a cumulative area of all pier sites for the bridge and the temporary bridge. Indeed, for the sites of permanent piers, there would be no more than 8 sites under construction concurrently within the subtidal and intertidal zone. Other permanent pier sites would be either still intact, or finished and occupied by the bridge piers which are smaller than the pier sites as shown in the sections below. The decks and piers of the temporary bridge will also be removed after the permanent bridge decks installed. So the actual area loss would be much smaller than 2.708ha at any time during the construction phase. Subtidal bentho survey and previous studies indicated that there is no rare benthic species in the area. The impact is thus considered insignificant. No mitigation is required.

9.7.11 Mainland-recognised fish nursery grounds in Deep Bay could possibly be affected by loss of marine habitat. However, because areas affected represent about 0.024% of the total seabed, impacts were predicted to be undetectable. This subject is addressed in greater detail in the fisheries impact assessment chapter.

9.7.12 The only taxa of known conservation concern in either the subtidal or intertidal zone are the three species of horseshoe crabs in Hong Kong. Detailed impact assessment for horseshoe crabs will be given below in Temporary habitat loss - Intertidal section.

9.7.13 Chinese White Dolphins were recorded 1.5 km from the proposed alignment in earlier studies (Jefferson 1998, 2000), but not closer than 8 km in SWC surveys. Given the combined total of 17 months of dolphin survey effort in Deep Bay from vessels and aircraft during the Crosslinks2 (12 months) and SWC field studies (5 months), and the absence of dolphins near the alignment during both of those studies, we conclude that the proposed alignment does not support dolphin habitat, therefore is not frequented by dolphins. It follows that bridge construction would pose no impact to dolphins.

9.7.14 Pier construction would create new areas of hard-substrate habitat in the subtidal zone of Deep Bay. While hard substrates are common at the Shekou coast, hard-substrate surfaces such as piers in the open waters of Deep Bay are lacking. Construction of the bridge piers might enhance the diversity of habitats available and provide new surfaces for settlement by encrusting species such as barnacles and bivalves. This potentially positive impact may be balanced against the impacts of muddy seabed habitat loss, but would not constitute in-kind habitat compensation. The ecological impacts of muddy seabed habitat loss are predicted to be undetectable due to the absence of species of conservation concern and the small percentage of total habitat that would be affected.

9.7.15 Temporary habitat loss - Intertidal: The bridge landing point at Ngau Hom Shek would cross mangrove plantations and mudflats at Ngau Hom Shek. The fauna species of conservation concern identified in the intertidal zone are horseshoe crabs and 10 species of waterbirds such as egrets, herons, and Black-faced Spoonbills which have been recorded on the mudflat nearby. Eight pairs of bridge piers and the temporary construction bridge would be required within the intertidal zone, resulting in intertidal habitat loss during construction. Construction equipment would require access to each pier site from the temporary bridge, resulting in extra short-term, temporary habitat loss due to its own piers. One of the main bridge's intertidal pairs would be in the mangrove plantation where we assume an additional loss of mangroves within the works area (50 x 50 m = 0.25 ha). Up to 0.25 ha of mangrove (assuming 50 x 50 m impact area in the mangrove) and 0.592 ha of intertidal habitats would be directly and temporarily affected by bridge construction, plus 0.16 ha would be affected by the temporary bridge (Tables 9.7.1 and 9.7.2).

9.7.16 Mudflat: Intertidal benthic infauna survey showed that there was no rare species present. The impact on mudflat fauna is ranked as insignificant. No mitigation is required. The mudflat, besides being the habitat of mudflat fauna, also functions as the feeding ground of birds and a potential nursery ground of horseshoe crab, the temporary loss of 0.752ha mudflat would have minor impact, when compared with the over 1,000 ha mudflat along the 15km south shore of Deep Bay (over 300 ha in Mai Po and over 700 ha from Tsim Bei Tsui to Ha Pak Nai). Mitigation is proposed for this impact.

9.7.17 Seagrass has only be recorded on the Ngau Hom Shek mudflats at a later stage of the present field survey programme, therefore the seagrass beds there are smaller and more patchily distributed than at Sheung Pak Nai and southwestward. The proposed pier locations are not in areas inhabited by seagrass (Figure 9.6), but several beds, measuring less than 1 m2 each, were recorded within the construction works area. They could potentially be affected though it would unlikely happen according to the current construction methods. . The total area of seagrass potentially affected would be less than 0.001 ha (<10 m2).

9.7.18 H. beccarii is widely distributed along the coasts of the South China Sea and has been recorded from numerous Southeast Asian countries. H. beccarii had been confirmed its occurrence at Black Point, at Lantau's Tai Ho Wan, and in Starling Inlet in addition to Deep Bay (Wong 1998, Frew and Yau pers. comm.). The Outer Deep Bay beds represent the largest known area for this species in HKSAR. As mentioned in previous sections, during the Crosslinks2 study, 2.5 ha of beds of seagrass Halophila beccarii was documented from Sheung Pak Nai extending southwest to Ha Pak Nai while none was recorded in the current SWC assessment area. During the present survey, the maximum area of seagrass recorded was only 0.9 ha, spreading along the entire 2.2km coastline from Sheung Pak Nai to Ngau Hom Shek. The seagrass beds recorded close the bridge alignment could be considered as the fringe of the main seagrass beds to the southwest of Sheung Pak Nai. Furthermore, during the current surveys, the area of seagrass beds recorded at different times ranged from about 0.6 to about 0.9 ha. The loss potentially caused by the present project (<0.001ha) is only 0.3% of the seasonal variation of seagrass from Ngau Hom Shek to Sheung Pak Nai (about 0.3ha). Though the area affected is very tiny, due to the lack of comprehensive distribution and abundance information of this species in Hong Kong, the impact is ranked as minor.

Mitigation measure is proposed.

9.7.19 Currently the oyster beds in Ngau Hom Shek extend from the edge of mangroves to several hundred metres seaward. The mudflat area beneath the bridge and 50m of either side will be cleared as marine works area for construction works. Oyster farming will not be allowed within this area since then. This will clear an area of mudflat about 8.34 ha (139m x 600m). The net increase of clear mudflat area will be at least 7ha even considering the temporary loss due to the bridge piers. Because seagrasses are relatively quick to exploit suitable habitats, this species will be expected to recolonize on the mudflats of better conditions.

9.7.20 Mangroves: One pair of bridge piers would be sited within the belt of mangrove plantation extending seaward some 50 m from the Ngau Hom Shek coast. We assume that the loss of mangrove in the works area there is total, thus construction of this pair of piers would result in loss of a 50 x 50 m area of mangrove plantation. The impact is ranked as minor. On-site mitigation through replanting would be required for loss of mangrove trees.

9.7.21 Black-faced Spoonbill (BFS): The preferred feeding habitats of wintering BFS in Hong Kong includes gei wais at Mai Po, draining fishponds in NWNT, and intertidal mudflats in Inner Deep Bay. Outer Deep Bay mudflats are used by a minority of the BFS winter population. During the 69 waterfowl counts by HKBWS carried out between January 1979 and March 2002 in Nim Wan/Lau Fau Shan, Black-faced Spoonbills were only recorded in 3 surveys. The cumulated number recorded was 28 (two records of one individual, and one record of 26 individuals). Compared with the number of BFS in Inner Deep Bay (usually close to or even over 100 individuals during the whole winter), the importance of mudflat in Outer Deep Bay to Black-faced Spoonbills is not considered high. In the present EIA study, BFS were recorded in the assessment area beginning in November 2001 and through March 2002. Numbers of BFS on the Ngau Hom Shek mudflat was zero for most of the time during baseline field surveys and did not exceed 9 (Appendix 9A), or 0.9% of the global BFS population, and some 6.6% of the Hong Kong population of 136. When BFS used the mudflats as foraging areas, they typically moved along the tideline parallel to the shoreline feeding in water of ±10 cm depth (estimated being a band of about 5m seaward from the tideline). Foraging BFS showed no affinity to any given segment of the mudflat, as would be expected of a species that feeds primarily on live fish. Even though, adopting the precautionary principle, we here still estimate the direct BFS feeding ground loss resulted from SWC construction sites. Estimating conservatively, the depth of the tideline used by BFS would be 10m seaward (double the 5m width), and the section of tideline not available for BFS would extend to cover the 50m works area, though the cofferdam sites would be located within the width of the bridge. Combined with the bridge width of 39 m the total width of a conservatively estimated zone of direct feeding ground loss would be 139 m (39 + 50 + 50 m). The total area of that zone would be 0.139 ha (139 m length x 10 m width = 1,390 m2 or 0.139 ha).

9.7.22 Previous studies indicated that mudflat is only one of the feeding ground types of BFS (the other two are drained fishponds and drained gei wais), and the outer Deep Bay (including the mudflat near the SWC alignment) is not the core feeding area of BFS. Since the mudflat in Ngau Hom Shek had been inundated by the oyster beds and oyster farming operation. The value for birds including BFS was further reduced. Therefore 0.139 ha represents a small fraction (0.927%) of the intertidal feeding habitat for BFS along the south shore of Deep Bay (some 15 km in length x 10 m in width = 15 ha) which is the peripheral feeding habitat of much lesser importance for BFS than the inner Deep Bay. A temporary loss of <1% of the available but peripheral foraging habitat is predicted to be an undetectable change and the impact is ranked as insignificant. No mitigation is required. It will, however, be benefited from the Additional Enhancement Measures (see Section 9.9) provided by this project.

9.7.23 For other waterbirds, including ardeids and the other 5 spp. of birds of conservation concern, their temporary feeding habitat loss would be equal to that for intertidal mudflat, i.e. 0.752 ha (0.592 + 0.16 ha). Indeed the function of the mudflat in the vicinity of the alignment as bird feeding ground was limited by the oyster farming operation. There was no significant difference in bird density or species richness among the three surveyed sites (Ngau Hom Sha Ngau Hom Shek and Sheung Pak Nai) during August to September 2001. An oyster bed was established on the intertidal mudflat at Ngau Hom Shek in October 2001. Oyster cultches occupied some of the feeding habitats of shorebirds and oyster farmers were frequently seen on the intertidal mudflat at Ngau Hom Shek since then. Significant difference in bird density and species richness were then recorded among the three surveyed sites (Appendix 9A). Bird density and species richness at Ngau Hom Sha and Sheung Pak Nai were significantly higher than those at Ngau Hom Shek after oyster beds established at Ngau Hom Shek. The impact is thus ranked insignificant and required no mitigation measure, as the function of the mudflat has been reduced by oyster farming, and most of the birds recorded can feed in other types of habitats in Deep Bay (e.g., fish ponds, gei wais). It will, however, be benefited from the Additional Enhancement Measures (see Section 9.9) provided by this project.

9.7.24 Horseshoe crab: As noted in Section 9.4 of this report, horseshoe crab numbers are low because of over-exploitation rather than habitat loss in Deep Bay. Juvenile crabs found during field surveys indicate that crab reproduction in Deep Bay continues. The two juvenile horseshoe crabs found were both at Ngau Hom Sha. During the survey period (August 2001 - June 2002), the mudflat in Ngau Hom Shek, i.e. the bridge landing point, has been progressively occupied by oyster cultches since September 2001. The physical occupation of the mudflat area by oyster cultches, the placement of oyster cultches and other activities of oyster farmers probably limited utilization of the mudflat by juvenile horseshoe crabs. Oyster farming has been practiced on the mudflat near the proposed landing point for many years. The landing point is thus not likely to be a regular nursery area for horseshoe crabs. The area of seabed affected by construction of the bridge piers is insignificant in comparison with the total seabed area of Deep Bay. Therefore bridge construction is not predicted to cause habitat loss that would reduce horseshoe crab survival or abundance in Deep Bay. The impact is ranked as insignificant. No mitigation is required.

9.7.25 As mentioned above, the mudflats in Ngau Hom Shek from the edge of mangroves to several hundred metres seaward were occupied by oyster beds. The mudflat area beneath the bridge and 50m of either side will be cleared as marine works area for construction works. Oyster farming will not be allowed within this area since then. This will clear an area of mudflat about 8.34 ha (139m x 600m). The net increase of clear mudflat area will be at least 7ha, even considering the loss due to the bridge piers. Seagrass is expected being able to colonising the re-exposed mudflats quickly. With the new colonised seagrass beds, the mudflats would be a more suitable habitat for horseshoe juveniles than it was.

9.7.26 Estimated loss of marine and intertidal habitat is given in Table 9.7.1.

Table 9.7.1 Estimated construction stage HKSAR temporary habitat loss due to SWC (assumes a 50 x 50 m mangrove impact area, and a 1800 m temporary bridge)

9.7.27 Disturbance - Marine: Submarine noise during construction of bridge piers could affect marine life in Deep Bay by causing organisms to flee areas affected by noise. Sources of construction noise could include construction of the temporary bridge, operation of construction equipment (e.g. sheetpilers) and construction-related vessel traffic. Construction equipment noise would vary based on the equipment used; high frequency sound was expected to be the most important in terms of potential impacts, rotary piling equipment would generate low-frequency, long-duration noise. Additional vessel traffic associated with construction is unlikely to cause detectable impacts, given the high existing levels of boat traffic. Impacts would be intermittent during the construction period (28 months). Potential noise receivers include benthic and pelagic invertebrates, fish and dolphins. The influence of noise would be localised. In light of the facts that dolphins do not occupy the area of the bridge alignment, there would be no impact to dolphins. Other organisms could move away from the area of noise disturbance, thereby avoiding impacts. Impacts were ranked as insignificant and required no mitigation.

9.7.28 Disturbance - Intertidal: Besides the direct habitat loss, the area of habitat on the bridge footprint and alongside it will be subject to disturbance from construction works. For species that occupy those habitats at carrying capacity this constitutes a temporary indirect habitat loss. Noise from construction processes and equipment, and activities of workers and construction equipment would be the major sources of disturbance in the intertidal area. The consequence of this impact would be reduced wildlife density or, in the extreme case, complete avoidance of the works areas by wildlife. This will result in a decline of the quality of the habitats, or a temporary indirect habitat loss. Similar to the direct habitat loss described above, this impact could have a greater impact upon species whose habitats are either scarce or near carrying capacity. The impacts will be localised along the alignment of the bridge. Disturbance would not affect wildlife activity at the Pak Nai SSSI (2.5 km away), Pak Nai Egretry (4 km away), or conservation sites in Inner Deep Bay such as Mai Po and Futian (5 km away). CMD International (2000) assessed potential construction noise impacts on the Pak Nai egretry for the proposed Ha Pak Nai WEF site. That study determined that, based on actual field experience of noise impacts resulting from the construction of Route 3, construction noise was unlikely to adversely affect the egretry which was situated some 500m from the proposed WEF site. Of the wildlife recorded in the Assessment Area birds are considered potentially most vulnerable to disturbance. However, not all species of birds are equally sensitive to disturbance.

9.7.29 In Shenzhen River Regulation EIA, it was also concluded that noise impacts generated as a result of construction would not be expected significant to birds. It, however, was proposed that the use of loud speaker should be controlled.

9.7.30 Exclusion zone concept was applied in Spurline EIA to assess the indirect impacts on birds during the construction and operation phase. In the assessment for the present project, the rationale used in Spurline EIA has been studied and compared with those for the present study. We found there are substantial difference in the nature of two projects. SWC is located at Outer Deep Bay and over 5km away from Mai Po, while Spurline is located at Wetland Conservation Area and Wetland Buffer Area in Inner Deep Bay and is less than 2 km from Mai Po. It is also part of the core feeding area of Black-faced Spoonbill. Besides the difference of marine and terrestrial habitats to be affected in the two project, the feeding habitat for birds in SWC is not fixed in location but a transient tideline, while in Spurline, the bird feeding ground of concern (fishponds) is in fixed locations. We have collected sufficient information from the field surveys, literature review and data from other projects to demonstrate that it is not necessary to directly apply the figures in Spurline study in terms of disturbance impacts. Our assessment, with reference to the information of Spurline, would be conducted by utilizing the information we consider most relevant to the present project.

9.7.31 Among the 22 species of birds to which exclusion distance were provided in Spurline EIA, only 7 species are in common with the bird species of conservation concerns in the present study (Black-faced Spoonbill, Grey Heron, Chinese Pond Heron; Great Egret; Little Egret; Great Cormorant; and Red-billed Starling). The Great Cormorant and Red-billed Starling are not relevant to the present project since both are not mudflat users. Great Cormorants mostly feed in fishponds in Deep Bay and roost at Mai Po and Nam Sang Wai (Carey et al. 2001), while Red-billed Starlings inhabit lowland terrestrial wetlands. The habitats of Cormorants and Red-billed Starlings are not going to be affected by the project. The major concerns would be the Black-faced Spoonbill and ardeids, which are assessed in details below. The difference in bird species composition reflects the difference in habitat type between the two projects.

9.7.32 Ardeids: Chinese Pond Heron, Little Egret, Great Egret and Grey Heron were regularly recorded on inter-tidal mudflat within the Assessment Area of SWC. These four species were also dominant species on inter-tidal habitats between Lau Fau Shan and Nim Wan outside winter. In terms of abundance, ardeids constituted the majority of birds recorded on mudflats during the field surveys. Other recorded species were present in small numbers or did not feed on mudflats. Ardeids are known to be tolerant to noise and disturbance. During the 2-year ecological monitoring project for construction stage impacts of the Shenzhen River Regulation Project (SRRP), we observed herons and egrets (Grey Heron, Little Egret, Chinese Pond Heron, Yellow Bittern, Cattle Egret, Night Heron and Great Egret) consistently using fishpond habitats adjacent to major earth-moving and river channeling works. Distances from construction haul roads to fishponds used by Grey, Night and Chinese Pond Herons and Great and Little Egrets were as close as 10 m. SRRP construction works involved dredging from vessels, hauling in dumptrucks, and extensive riverbank paving by large numbers of personnel. Haul truck traffic was frequent and noisy. SRRP monitoring studies also showed that the total densities of Chinese Pond Heron, Little Egret, Great Egret and Grey Heron within 100m from the new embankment of the channelised Shenzhen River were similar in construction and operation phases (Appendix 9D). This showed that construction noise and disturbance did not cause significant population impacts to these species.

9.7.33 Most of the species listed above are relatively tolerant of anthropogenic noise and activities.

9.7.34 Based upon the above observations in HKSAR, the absence of indication of direct mortality or reduced nest productivity in waterbird nests near sites characterised by high levels of human activity, and the fact that construction impacts would be confined to works areas, impacts of construction works to herons and egrets foraging on mudflats are predicted to be insignificant. No mitigation measure is required. It will, however, be benefited from the Additional Enhancement Measures (see Section 9.9) provided by this project.

9.7.35 Black-faced Spoonbills might be expected to be less tolerant of noise and activity. This was not the case at Macau SAR (Appendix 9C), where landfill operation, urban road construction, highway landscape maintenance, human recreation and urban traffic all took place within 50-200 m of flocks of 10-30 BFS. When a speedboat was passing through the navigation channel, the feeding behaviour of a group of BFS about 30m away was not affected. Our surveys indicated that the chance of BFS affected by disturbance sources 50m or more away was remote.

9.7.36 A 50m distance from the construction sites (50m works area, which is primarily purposed for vessel access), however, has been covered by the assessment of temporary BFS habitat loss above. There would be no additional BFS habitat loss resulted from the construction disturbance.

9.7.37 Adopting the precautionary principle and considering the global population status of BFS, we here estimate the indirect BFS feeding ground loss potentially resulted from the worst case scenario (Disturbance occurs in the exposed intertidal zone during low tide within the 50m works area, which is primarily purposed for vessel access in subtidal zone or, during high tide, in intertidal zone.) As described in the previous section, BFS typically moved along the tideline feeding in water of ±10 cm depth. Feeding BFS moved parallel to the shoreline foraging in a band of habitat estimated to be 5m seaward of the tideline. We assume that BFS will avoid a section of the tideline closest to the alignment. Estimating conservatively, the depth of the tideline used by BFS would be 10m seaward (double the 5m width), and the avoided section of tideline could extend 50m from the boundary of the 50m works area which is primarily purposed for vessel access during only high tide (more than the distance from a source of high level disturbance, i.e. a speedboat, recorded in Macau). Combined with the bridge width of 39 m the total width of a conservatively estimated zone of avoidance would be 239 m (39 + 50 + 50 + 50 + 50). The total area of that zone would be 0.24 ha (239 m length x 10 m width = 2,400 m2 or 0.24 ha).

9.7.38 As detailed in the assessment of temporary habitat loss for BFS, previous studies indicated that mudflat is only one of the feeding ground types of BFS (the other two are drained fishponds and drained gei wais), and the outer Deep Bay (including the mudflat near the SWC alignment) is not the core feeding area of BFS. Therefore, even under the worst case scenario, 0.24 ha represents a small fraction (1.6%) of the peripheral intertidal feeding habitat for BFS along the south shore of Deep Bay (some 15 km in length x 10 m in width = 15 ha). The average of < 1-2 BFS per survey day seen between December and May may avoid the vicinity of the construction sites, and forage at Ngau Hom Sha, Sheung Pak Nai, or Pak Nai. A temporary loss of <2% of the available but peripheral foraging habitat would not be expected to reduce probability of survival or subsequent nest productivity of BFS, and is predicted to be an undetectable impact. This impact is ranked as insignificant and no mitigation is required. It will, however, be benefited from the Additional Enhancement Measures (see Section 9.9) provided by this project.

9.7.39 Other birds: Other bird species recorded within the assessment area were either not a mudflat user, such as cormorant, or in very low abundance. They were thus not considered as receivers of the disturbance impacts. Besides ardeids and Black-faced Spoonbill, there were 10 bird species feeding on inter-tidal mudflat or tidelines, including the remaining 5 of the 10 bird species of conservation concern. Of which Curlew Numenius arquata was the most numerous species (41.6% of total birds on tidelines). In spite of the high percentage in the SWC surveys, the majority of Hong Kong records of this species and Redshank Tringa totanus comes from intertidal mudflat of Mai Po Marshes Nature Reserve and only 2% of the records are from other localities (Carey et al. 2001), including the assessment area of SWC. In SWC surveys, however, they were only abundant in Sheung Pak Nai tideline. Bird species other than ardeids, spoonbills and curlews were only present in low numbers, accounted for 10% and 2.4% of total birds on mudflat and tideline respectively. In addition, some of these species (e.g., Common Sandpiper Actitis hypoleucos, Little Ringed Plover Charadrius dubius, White-breasted Kingfisher Halcyon smyrnensis) are inhabitants of disturbed areas. Inter-tidal mudflat is also not the preferred habitat of Wood Sandpiper Tringa ochropus. The impact of disturbance on these species is considered insignificant. Osprey Pandion haliaetus, as a bird of prey, may hold a home range with radius about 40-50 km (Hammond & Pearson 1993). Due to the transient nature and being confined to the work area, disturbance impact on osprey was also considered insignificant. No mitigation measures is required. It will, however, be benefited from the Additional Enhancement Measures (see Section 9.9) provided by this project.

9.7.40 Seasonal difference: Bird communities of intertidal habitats and stretch of coastlines between Lau Fu Shan and Nim Wan (6 km) (NW/LFS in Waterfowl Count Reports of The Hong Kong Bird Watching Society (HKBWS)) were surveyed 69 times between January 1979 and March 2002 in the Waterfowl Count organized by HKBWS (Agriculture and Fisheries Department undated, Carey 1998, 1999b, 2000, 2001, 2002). Peak counts were always recorded in winter (November to March) (Figure 9.8). The mean bird abundance during winter (November to March) and outside winter (April to October) in NW/LFS between November 1997 and March 2002 was 368 birds and 109 birds respectively. Bird abundance on inter-tidal mudflats between Nim Wan and Lau Fau Shan in non-winter seasons is on average one third of that in winter (Nov - Mar). The dominant species are all winter visitors and do not occur in Hong Kong in other seasons. Species recorded in certain abundance throughout the year in NW/LFS were Little Egrets and Chinese Pond Herons. During non-winter seasons, bird species on inter-tidal mudflats between Nim Wan and Lau Fau Shan were mainly ardeids, and other species generally of low conservation concern (e.g., White-breasted Waterhen Amaurornis phoenicurus, Common Kingfisher Alcedo atthis). The species of greatest conservation concern, BFS, does not normally occur in Hong Kong from April through October. Thus, from the standpoint of bird abundance and conservation concern, disturbance impacts on birds during the construction phase would be even lesser in spring-summer-autumn than in winter. As all bird species in summer (June to August) during Waterfowl Count can also be recorded in other times of the year, no impact assessment specific to summer migratory season (June to August) is necessary.

9.7.41 Night time works: It is anticipated that night time works would be needed to accomplish the tight construction work programme. Previous study revealed that the feeding activities of Black-faced Spoonbill would continue at night. There is a concern on whether the lighting and noise from night time works would affect BFS feeding. Due to the regulation of noise level for works during restricted hours, night time works of SWC could only be conducted at locations over 1000m from the coastline. This distance would be more than enough to buffer any disturbance of lighting or construction activities from, if any, BFS feeding on the mudflat near Ngau Hom Shek. For most days in a month, the tideline would be within about 500m from the coastline. Indeed, lighting also exists along the boundary fence. There is no record that the lighting on police watch tower would affect BFS feeding activities. The disturbance from night time works would be even milder to birds than that in day time because of the long distance from the coastline.

9.7.42 Marine water quality - Suspended Solid: Construction of bridge piers, which involves dredging, in Deep Bay, the bed of which is covered in a deep layer of mud, could locally affect water quality in the vicinity of the dredging sites. Water quality parameter of concern would be suspended solids (SS) levels. Resuspended sediments could contain contaminants which could enter the water column, while resettled sediments could smother benthic fauna. These water quality impacts could have negative consequences, mostly indirect, for both benthic and pelagic organisms. For the case of unconfined dredging, the potential impacts to the surrounding water may be significant.

9.7.43 In most cases, suspended sediment associated with dredging and reclamation is the major source of indirect impact to marine ecology. The baseline suspended solid conditions in Deep Bay are quite variable, being influenced strongly by seasonal variations, tidal flows, storms, and fishing vessels. Deep Bay organisms are thus adapted to periods of high suspended sediments. The effect of suspended solids is difficult to quantify. In a recent study on marine ecological impact assessment criteria, the standard on suspended solid was selected based upon the no harm dosage for diatoms, rather than upon the actual effect dosage on marine organisms (City University of Hong Kong 2001). The rate, season and duration of SS elevations will determine the type and extent of impacts upon marine organisms.

9.7.44 Impacts of pier excavation and construction would most likely continue for up to 28 months. The severity of impacts will depend upon factors including the number of piers, the number of pier sites being excavated simultaneously, and the depth of the silt layer on the seabed. Works would require approximately 7.5 weeks at each pier site, and for noise control reasons no more than three pier sites would be under construction in the intertidal zone at a given time. The critical period for the construction of bridge piers would be from June 2004 to Sep. 2004. Two pairs of bridge piers would be constructed simultaneously in the intertidal area (600 m from coastline), while 3 pairs would be constructed simultaneously in the intertidal area beyond the distance of 600m from the coastline at Ngau Hom Shek, and 3 pairs in subtidal area.

9.7.45 The potential for sediment resuspension in the present project was predicted to be very low, since only limited dredging would be required for pier construction, enclosed rotary piling would be used, and piles would be bored inside casings that are in turn contained within cofferdams surrounded by silt curtains. These measures could effectively prevent any significant increase of suspended solid levels. No release of sediment is normally expected according to the proposed construction method. Impacts will be mitigated to acceptable level. Even in the case of failure of those mitigation measures, effects would be localised in nature due to the slow speeds of water movement in Deep Bay, on the order of 0.2-0.4 m/s.

9.7.46 Sediment plume modelling was conducted to predict the increase in suspended solids in the water column due to the release of sediment from bridge construction. To take a more conservative approach, the potential water quality impacts arising from bridge pier construction within the Hong Kong waters were assessed based on 8 pairs of pier sites (see Section 7 of this report, Water Quality Impact Assessment). Results indicated that no significant elevations of suspended solid due to dredging were found in all modelling cases. None of the elevation in indicator points exceeds 10 mg/L, which was reported in the Mainland EIA that no significant impacts on aquaculture would be resulted. There would be no exceedance of WQO for SS (<30% increase of the background value).

9.7.47 Even during the critical period, water quality modelling indicates that the changes would be minor and there would be no significant adverse impacts to water quality. Impacts on water quality during the entire construction phase would be even lower and therefore acceptable. This in turn indicates the impacts on marine ecology during the construction phase would be acceptable. Ecological impacts, with the construction method described above, were therefore ranked as minor.

9.7.48 Marine water quality - Contaminants including TBT: Potential releases of contaminants from dredged sediments into the water column during the dredging operations could affect the water quality and aquatic environment near the dredging sites. Besides the major water quality parameters of concern such as suspended solids (SS) levels, resuspended sediments could contain contaminants which could enter the water column. These water quality impacts could have negative consequences, mostly indirect, for both benthic and pelagic organisms.

9.7.49 Elutriate tests were also conducted to estimate the amount of contaminants that would release from the marine sediment during the dredging activities. The tested parameters included heavy metals and organic micro-pollutants (PCBs, PAHs, and TBT).

9.7.50 PAHs and total PCBs were below the detection limits. Other contaminants were of low concentration. Release of copper, zinc, and arsenic from marine sediment was not likely to cause adverse water quality impacts to Deep Bay. The release of these compounds during dredging would be insignificant, except TBT. For TBT, the highest amount released was found at D2, with a value of 1.816 mgTBT/L. The release of TBT from the sediment samples collected at D1, D3 and D4 were also relatively high. These locations were mostly located near the shoreline at Ngau Hom Shek. The impact would be minor in nature.

9.7.51 In the elutriate tests, sediment samples were vigorously agitated in the seawater. This might increase the release of TBT into the seawater resulting in high TBT levels. The real situation at the dredging sites in the present project would be different. Based on the preliminary engineering design, the piles for supporting the bridge sections would be constructed in the form of bored piles. A casing will be driven into the marine sediment layer prior to the excavation of marine sediment inside the casing. The seawater inside the casting will also pumped put to barges before dredging. The casing provides a confined and dry environment to avoid releasing of sediment into the surrounding water. In addition, cofferdams, which are larger than the pile caps of the bridge piers, would be installed at all pile sites prior to carrying out of any dredging works for construction of pile caps. Sediment dredging would then be carried out within the cofferdams. This construction method could minimise the release of TBT into the water column. By adopting these preventive measures, it is considered that dredging even at the locations with high TBT release potential would not cause adverse impact to the aquatic life and ecologically acceptable.

9.7.52 Marine water quality - Flushing Rate: Reduction in flushing rate is another concern related to water quality. As described above, a cofferdam larger in size than the bridge pier and pile cap would be constructed at each pier site to mitigate the suspended solid impact. The cofferdams themselves, however, would restrict water discharge capacity more than a bridge pier. At the initial stage of the construction works, only some of the bridge piers would be under construction, and thus the overall effect on tidal flow is likely to be lower than the operation phase of SWC, i.e. when all bridge piers are in place. During the construction phase, however, when 8 pairs of piers would be under construction at the same time and the rest of the piers have already been completed, the reduction in tidal flow across the bridge alignment is expected to be higher than during the operation phase. During the construction stage, about 43 ha (39m of the alignment and 50m either side of the alignment) will be occupied within HKSAR waters as marine works areas. Within the marine works area, existing oyster beds will be cleared during the bridge construction phase. The area will not be available for oyster farming even after the construction phase. The removal of oyster beds within the works area would have positive effect on the water quality during construction phase, i.e. could partially compensate the reduction in discharge capacity caused by the cofferdams, especially during the critical construction period of May 2004 to September 2004, during which eight pairs of piers will be under construction simultaneously. Even during this period, hydrodynamics modelling indicates that there would be no significant adverse impacts to the tidal flow. On the other hand, the presence of oyster cultches creates friction to the tidal flow due to the highly irregular surfaces of the oyster cultches and oysters. Hydrodynamics modelling results showed that with the clearance of oyster beds, the obstruction to the tidal flow would be reduced. This could counterbalance the reduction in discharge capacity caused by the concurrent construction of bridge piers during the critical period. With the clearance of oyster beds within the works area, it is expected that the hydrodynamic conditions in Deep Bay during the critical period for construction would be improved and would not be much different from the rest of the construction phase. The impact on flushing rate is ranked as insignificant.

9.7.53 Table 9.7.2 summarises the potential impacts of construction of the SWC.

Table 9.7.2 Construction-phase Impacts of the SWC

Operation Phase Impacts

9.7.54 Calculation of pier cross section: For the purpose of operational phase impact assessment we assumed the permanent loss of mudflat on the HKSAR side of Deep Bay to be equivalent to the cross-sectional area of the columns, calculated as follows.

· Movable-joint and fixed pier cross-sectional area = (36 pairs x 2 piers/pair) x (6 m x 2.5 m area) = 1,080 m2 or 0.108 ha;
· Expansion-joint pier cross-sectional area = (4 pairs x 2 piers/pair) x (6 m x 4.5 m area) = 216 m2 or 0.0216 ha;
· Total cross-sectional area of columns = 0.108 ha + 0.0216 ha = 0.1296 ha;
· Subtidal cross-sectional area = [4 pairs x 2 piers x (6 x 4.5 m area)] + [28 pairs x 2 piers x (6 x 2.5m area)] = 1,056 m2 or 0.1056 ha; and
· Intertidal cross-sectional area = [8 pairs x 2 piers x (6 x 2.5 m area)] = 240 m2 or 0.024ha.
There are also several ship protection structures called dolphins near the piers on both sides of the navigation channel. The subtidal sea area occupied would be:
· Dolphins for ship protection = [(18m x 15m x 2) + (10m x 10m x 2) + (10m x 8m x 2)] = 900m2 or 0.09ha.

9.7.55 Permanent habitat loss - Marine & Intertidal: For the purpose of operational phase impact assessment we assumed the permanent loss of seabed and mudflat on the HKSAR side of Deep Bay to be equivalent to the cross-sectional area of the columns and dolphins as calculated above (0.1956 ha in subtidal zone and 0.024 ha in intertidal zone). Compared with the total 11,500 ha of Deep Bay seabed and the over 1,000 ha of mudflat (over 300 ha in Mai Po and over 700 ha from Tsim Bei Tsui to Ha Pak Nai) along the 15km south shore of Deep Bay, the permanent habitat loss would be insignificant and no mitigation is required.

9.7.56 The section of tideline right beneath the bridge would be interrupted by the bridge piers. Black-faced Spoonbill feeding behaviour might be affected within this area. We assume the entire width of the bridge would not be available for BFS feeding, though the width of the piers would be smaller than that of the deck. There would be a permanent loss of 39m x 10m = 0.039ha of BFS potential feeding ground. Though there is no evidence to prove that BFS would avoid the mudflat in the vicinity of a bridge, we, however, did not record BFS feeding at a distance closer than 30m from disturbance sources or a bridge during the two-day survey at Macau in March 2002. Based upon a precautionary approach, we here included an additional 30m on both side of the SWC deck width to address this potential impact. The permanent loss of BFS potential feeding ground would then be (39m + 30m + 30m) x 10m = 0.099ha. It should be noted that currently the mudflat along the alignment and in the vicinity is occupied by oyster beds. Oyster cultches themselves and the oyster farmer activities would affect bird feeding behaviour. A much lower bird density was recorded after the installation of oyster cultches in Ngau Hom Shek (see Appendix 9A). Oyster beds within the alignment and the 50m works area will be permanently cleared at the commencement of construction works. A 8.32 ha restored mudflat (139m x 600m - 0.024 ha occupied by the piers) would be provided in the clearance area in operation phase. For BFS, a 0.139 ha tideline feeding ground (= (39m + 50m + 50m) x 10m) will be provided. After reduction of the 0.099 ha potential loss, there still would be 0.04ha tideline feeding ground restored. The impact is thus ranked as insignificant and no further mitigation is required. It will, however, be benefited from the Additional Enhancement Measures (see Section 9.9) provided by this project.

9.7.57 Fragmentation - Marine: The subtidal habitat was not expected to be fragmented as the loss of seabed area is very small and the current and tide flow will not be affected by the bridge. Impact would be insignificant and no mitigation is required.

9.7.58 Fragmentation - Intertidal: True Fragmentation: Observations of birds using the intertidal section of drainage channels beneath the Route 3 flyover showed that birds will feed beneath a bridge. The mean density of ardeids beneath the Route 3 flyover in winter 2001/2002 exceeded that more downstream of Channel 60 CD (Contract B) where there were no flyovers. This demonstrates that shading of the mudflat by a bridge did not cause adverse impact on ardeids, and the bridge above would not cause a change of habitat beneath and thus a fragmentation of habitat.

9.7.59 There is no situation in HKSAR that combines a bridge with intertidal mudflats and BFS. Therefore we expanded our field studies to include the Lotus Bridge between Macau SAR and Zhuhai SSEZ (Additional bird-bridge survey). Results of that study were reported in Appendix 9C, and are summarised here. While the waterbird attraction to the man-made mudflat near the Lotus Bridge was the availability of prey there, bird use of the mudflat varied spatially. Overall average density of waterbirds on the mudflat in March 2002 was 4.84 birds per ha (from 550 m north of the bridge to 1,500 m south of the bridge). Average density of birds beneath the Lotus Bridge was 1.6 birds per ha (Figure 9.13c).

9.7.60 Birds recorded foraging beneath the bridge included Chinese Pond Heron, Grey Heron, Great Egret, Little Egret and White Wagtail Motacilla alba. Chinese Pond Heron, Great Egret and Little Egret were commonest on inter-tidal habitats between Lau Fau Shan and Nim Wan outside winter. Average density of birds feeding in an effluent stream draining the nearby solid waste landfill was 84.22 birds per ha. All four of the species recorded beneath the bridge also fed in the stream draining the landfill. Both BFS and European Spoonbills fed in the effluent stream where it crossed the mudflat.

9.7.61 Lower densities of waterbirds feeding beneath the Lotus Bridge may be attributed to three characteristics of the mudflat there (see Figure 9.13):

· uneven micro-topography and consequently varying water depths and mud elevations beneath the bridge caused by poor quality mudflat restoration after bridge construction (Figure 9.13d);
· presence of discarded construction materials and equipment on the mudflat; and
· water level may be too shallow for species normally feed in tidelines (e.g., Black-faced Spoonbill).

9.7.62 In the SWC case, mitigation measures to restore the mudflat within the 50m works area after construction, including restoring the original profile and clearance of all construction materials or wastes, would be provided (see Section 9.8). The limitations on bird use will not exist. The impact is ranked as insignificant and no mitigation is required.

9.7.63 Barrier effect: All bridge study sites used during the course of Additional bird-bridge study of this EIA were in operation at the time of field studies. Birds flew over or beneath all studied bridges. The barrier effect of a bridge might be regarded as an alternative form of habitat fragmentation in that the physical presence of the bridge could be predicted to affect bird flight. Should birds fail to pass over a bridge alignment to utilise habitats on the opposite side, the mudflat habitat would then be considered fragmented in terms of function though it would remain physically undivided. The hypothesis of habitat fragmentation by a bridge was tested by study of bird responses to the Lotus Bridge in Macau, where BFS and ardeid foraging and roosting habitats were found on opposite sides of the bridge alignment. Results of that study are summarized in Figure 9.14, which shows the bridge and BFS feeding and roosting areas in relation to surrounding man-made mudflats (Co-Tai Reclamation), man-made freshwater marsh (Co-Tai Reclamation), solid waste landfill, and urban areas of Taipa and Coloane. Field studies in Macau SAR revealed that BFS, Great Egret, Little Egret, Chinese Pond Heron, and Grey Heron routinely flew between a man-made freshwater marsh where they roosted (Co-Tai Reclamation), and a man-made intertidal mudflat or solid waste landfill where they fed. Great Egret, Little Egret and Chinese Pond Heron are the commonest species in Outer Deep Bay outside winter. This is depicted on the map insert on Figure 9.14. Total numbers of birds involved in this flight pattern were approximately 190, some 20-30 of which were BFS. This routine flight pattern of the birds across the Lotus Bridge, a 6-lane concrete bridge on pairs of piers that, in terms of height and width, would be similar to that of the proposed SWC bridge. During winter 2002 birds dealt with the Lotus Bridge by flying over it (all BFS, most herons and egrets) or flying under it (some herons and egrets). During timed counts some 28 herons and egrets flew beneath the bridge per hour. These included Chinese Pond Herons, Grey herons, Great Egrets, Intermediate Egrets, and Little Egrets. BFS and European Spoonbill, i.e. spoonbills as a whole, generally behaved similar to ardeids, with the exception that BFS were not seen flying beneath the bridge. A couple species were also observed flying over (e.g., White Wagtail Motacilla alba, Crested Myna Acridotheres cristatellus) or below (e.g., Common Sandpiper Actitis hypoleucos, Greenshank Tringa nebularia) the Lotus Bridge. In fact, no report of bridge as barrier to bird flight, nor barriers to particular bird group/species, has been found. The impact is ranked as insignificant.

9.7.64 Observations for operating bridges showed that bridges present no barrier effect on birds. When the whole bridges do not form barrier to bird movements, it is obvious that "portion" of bridge during construction phase will not be barrier to birds.

9.7.65 Based upon the facts that large numbers of waterbirds (including Grey Heron, Great Egret, and BFS) routinely roosted and fed on opposite sides of the Lotus Bridge, some waterbirds foraged beneath the bridge (Grey Heron, Little Egret, Chinese Pond Heron), waterbirds routinely flew over or under the bridge to make the twice-daily shift from marshland roost to mudflat feeding area, no birds were seen to collide with the bridge or vehicles on it, and the Lotus Bridge has characteristics that would be expected to discourage bird flight and foraging beneath the bridge deck, we conclude the following:

· The Lotus Bridge did not constitute a barrier to bird flight;
· Neither vehicle noise on the bridge deck, nor vehicle noise and landscape maintenance personnel and equipment below the bridge (at ground level) deterred bird use of the mudflat near and beneath the bridge; and
· Lower densities of feeding birds beneath the bridge than on the nearby mudflat could be addressed through implementation of mitigation measures that have been proposed for the SWC bridge.

9.7.66 Studies of bird responses to bridges over mudflats or water in HKSAR and Macau suggest that the impact of habitat fragmentation at Ngau Hom Shek would be insignificant. Birds have been observed feeding under bridges and flying both beneath and over bridges (Appendix 9A & 9C). Black-faced Spoonbills at Macau foraged and roosted near a recently constructed 6-lane bridge in January and March 2002, and were observed flying (together with 1 European Spoonbill Platalea leucorodia and numerous herons and egrets) over the bridge between intertidal mudflats and freshwater wetlands. This suggests that impacts of bridge operation would be undetectable. We found no evidence during field studies to indicate that bird use of the mudflat at Ngau Hom Shek would be altered in a negative way by the operation of the bridge. Rather, the results of our local field studies indicate that birds would continue to use the mudflat as they did prior to bridge construction.

9.7.67 Disturbance - Marine: Intensity of marine traffic noise and disturbance from vessels using the navigation channels would be unrelated to and unaffected by the presence of the bridge. No significant disturbance impacts are expected and no noise reduction measures are required.

9.7.68 Disturbance - Intertidal: A much lesser degree of disturbance would be expected from the operation phase. The noise levels generated by traffic on the bridge deck would be of low intensity (see Noise chapter). Human activity beneath the bridge would be infrequent. Low intensity noise and predictable sources of human and equipment activity are considered non-threatening to wildlife. Furthermore, oyster farming would not be conducted within the original 50m works area. Disturbance from oyster farmer activities would not appear within that area.

9.7.69 Traffic noise is not predicted to pose a potential environmental impact, and no noise barriers are proposed for the bridge. All bridges studied during the course of this EIA were in operation at the time of field studies. Birds, mostly ardeids, flew over or beneath all studied bridges. Birds, including ardeids and other waterbirds (e.g., Common Sandpiper, Greenshank), were observed feeding under and near the Route 3 flyover and Lotus Bridge. A large number of waterbirds (e.g., Cormorants, ardeids, spoonbills, Avocet Recurvirostra avosetta, gulls Larus spp.) was frequently seen feeding in the mangrove plantation of channel 60 CD (Contract B) in Kam Tin River during winter, when there is also some traffic on the access roads on the two side of the channel. Birds also nested on structures supporting the Route 3 flyover (Appendix 9C). For these reasons noise is not considered to be a potential ecological impact to birds, including species of conservation concern recorded.

9.7.70 Wildlife may become accustomed to regular sources of noise, even if loud, as evidenced by birds living on airfields (e.g., Little Ringed Plover, Wood Sandpiper Tringa glareola) (Melville 1980) or nesting near heavy traffic flow (Lansdown et al. 2000). Ardeids are much more tolerant to noise, even in breeding season. At least two ardeid nesting sites in Hong Kong (the former Tai Po Market egretry adjacent to a busy railway station, the Mai Po Village SSSI egretry over a road) were established and occupied annually in areas with high levels of human activities (Lansdown et al. 2000). The Mai Po Village SSSI egretry is one of the largest and oldest colonies in Hong Kong (Young and Cha 1995). Many other smaller ardeid nesting colonies are also near high level of human activities (e.g., Mai Po Lung Egretry, Stonecutters Egretry, Penfold Egretry). The traffic noise from SWC in operational phase would not be expected to adversely affect wildlife.

9.7.71 Traffic flow: It is well known that birds are much less sensitive to moving objects other than human, such as vehicles. Large number of ardeids used to roost on mangroves and waterbirds (e.g., sandpipers) are frequently feed on mudflat within 30 m from the KCRC railway between the Tai Po Market and University Stations. As stated above, a large number of waterbirds forages in mangrove plantation near light to moderate traffic. Based upon results obtained from study of 3 bridges in Hong Kong (Route 3 flyover, the Shatin Road above Shing Mun River Channel and Tsing Tsuen Bridge) and one in Macau (the Lotus Bridge), we concluded that waterbirds would forage near and even beneath bridges on mudflats with no detectable adverse impacts. It is predicted that traffic flow will cause insignificant impact to bird species of conservation concern recorded. Birds were recorded flying above and beneath bridges in intertidal zones in Hong Kong and Macau regardless the intensity of traffic flow on the bridge surface (Appendix 9C).

9.7.72 International experience shows that Cormorants nest on the San Francisco-Oakland Bay Bridge to such an extent that authorities have implemented a project to install nesting platforms on the bridge to enable safer and more frequent Cormorant nesting. A second example is San Sebastian State Recreation Area (Florida, USA) where Royal Terns and Brown Pelicans sought refuge on a bridge over an intertidal area during high or erratic wind conditions. The birds did not collide with the bridge or any associated structure, but rather attempted to land on the bridge deck to escape gusty winds that made flight difficult. In this case the bridge attracted birds rather than repelling them. A third example is provided by the National Estuary Program (NEP) sponsored by the Environmental Protection Agency in USA. Included in the NEP are 28 of the largest and most important estuaries for habitat and biodiversity conservation in USA (see http://www.epa.gov/nep/index.html). All of the NEP estuaries have roads and bridges, and some of the bridges are landmarks (Galveston Bay Bridge, San Francisco-Oakland Bay Bridge and others). In no case do any of the 28 participating estuaries cite adverse impacts of bridges on birds or other wildlife. A final example of wildlife-bridge interaction is the Chesapeake Bay Bridge-Tunnel, which spans the mouth of Chesapeake Bay, the world's third largest, and North America's largest estuary. Rather than adversely affecting wildlife, the bridge is used by the public as a wildlife viewing platform. Four man-made islands along the 32 km bridge-tunnel alignment are provided with car parks for use by bird watchers and other tourists. The islands now serve as important bird monitoring sites to inventory the millions of waterbirds that migrate twice annually along the Atlantic coast of North America (see http://www.cbbt.com). In addition to the birds whose migration paths include Chesapeake Bay, the site is home to the world's largest population of resident Ospreys that includes some 3,000 birds.

9.7.73 Based upon the BFS population increase in the face of the Co-Tai reclamation and construction of the Lotus Bridge in Macau, the BFS population in HKSAR is sufficiently protected from any influences of the SWC project. An operation disturbance zone for BFS was also included in the estimation of permanent habitat loss in the above sections according to the precautionary approach even though the possibility is remote. From SWC field studies and the above examples, we predict impacts upon birds or other wildlife in the intertidal zones from operation of the SWC bridge would be insignificant. It will, however, be benefited from the Additional Enhancement Measures (see Section 9.9) provided by this project.

9.7.74 Collision: Extensive literature review in Appendix 9B (>1,500 references spanning the last 117 years) and personal communications with professional colleagues throughout the world suggest that bridge impacts upon bird mortality and flight paths are insignificant (see Appendix 9B). It could be argued that bird collisions with bridges have not been addressed in the literature or in applied research projects because dead or stunned birds simply fall into the water and are not seen or recovered. However, some seabird carcasses float on seawater, and are detectable (Podolsky et al. 1998). Also, if collision frequency were high, at least some birds would fall onto the highway surface, thereby alerting wildlife researchers and managers and highway-bridge authorities to the existence of a problem. Indeed, this was the case on the Pensacola Bay Bridge, where bird carcasses on the bridge deck alerted authorities that a problem had developed. In that instance the problem was bird collisions with a power line suspended above the bridge deck between the light poles that illuminated the bridge roadway. Lowering of the powerline to the bridge deck in 1947 solved the problem. Based upon the overwhelming evidence in the global scientific literature that birds collide with some man-made structures, but not with bridges, and upon personal communications with professional colleagues working in areas where bridges and birds are both abundant, but adverse impacts are not seen, we predict that the SWC bridge would have little or no impact upon bird mortality. Field work in Macau at the Lotus Bridge supported this conclusion: No birds collided with the bridge or with vehicles on the bridge during 4 days of field study. Similarly, the bridge would not adversely affect bird use of short-distance (local) or long-distance (migration) flight paths. This prediction is supported by professional colleagues working in areas such as the Netherlands, San Francisco-Oakland Bays, and Japan where bridges and birds are both abundant and impacts are undetectable (C. Swennen, M. Rauzon, S. Chan, pers. comm).

9.7.75 Having predicted no significant impacts upon bird mortality or use of flight paths, it must be noted that Hong Kong has no experience with large, partially cable-stayed bridges near the Ramsar Site or any local area of known high bird abundance. To partially compensate for this lack of experience we studied bird movements in relation to 3 bridges or flyovers in Hong Kong, and one in Macau (Appendix 9C). The results of those studies showed that waterbirds foraged beneath bridge decks and flew either under or over bridge decks. We recorded no bird mortality due to collisions with bridges, piers, or vehicles using bridges. Highways Department has routinely monitored bridge and highway structures in HKSAR since the 1970s. During the succeeding 30 years the only recorded birds kills have occurred at newly erected and relatively transparent noise barriers. No noise barrier is proposed for the SWC bridge. Global experience of bird-bridge interaction includes suspension and cable-stayed bridges of a wide variety of designs, and never have such bridges been cited as vectors of increased bird mortality (see Appendix 9B). Although the global experience of bird-bridge interaction includes cable-stayed bridges, none of the local situations we studied included bridges with cable-stayed spans. This is because no such bridge occurs in HKSAR in an area of high frequency bird use. This lack of local experience suggests that a precautionary approach should be adopted, hence mitigation of potential impacts is recommended (Appendix 9B, Section 9).

9.7.76 Lighting: Appendix 9B discusses the impacts of various types of lighting on bird mortality and concludes that flood lights deployed under adverse weather conditions can confuse migrating birds and increase mortality due to collisions with structures other than bridges (particularly telecom and ceilometer towers). Although bridges are not included among the structures causing increased bird mortality, we applied the precautionary principle and listed design measures in Appendix 9B to avoid any potential impacts. Nocturnally active species that could be affected by lighting include Black-faced Spoonbills, Night Herons, Grey Herons, and bats and other nocturnal mammals. Lighting on the bridge deck (for vehicles) and undersurface of the bridge (for vessels) would be focused upon the bridge, thus would scatter less light into the surrounding environment than would normal urban lighting. Regardless, there would be an increase in the intensity of ambient light in Deep Bay. This could have an impact similar to but less than that of the urban lights of Shenzhen. Relatively intense waterbird use of Futian National Nature Reserve and portions of HKSAR near Shenzhen River suggests that urban lighting in Shenzhen exerts a minor or insignificant impact on birdlife. Bats are known to feed on insects attracted to lights, so impacts to bats could be positive (depending upon the type of lighting used, and whether it attracts insects). Experience gained at the Congress Bridge in Austin, Texas (USA) is relevant: Congress Bridge shelters the world's largest colony of Mexican Free-tailed Bats (several million bats; see website for Bat Conservation International, www.batcon.org), but collisions with vehicles on the bridge and other potentially adverse impacts of lighting are not reported. The bridge is observed daily by up to hundreds of tourists and other bat watchers viewing the daily departure of bats from the bridge. Other nocturnal mammals would not be expected to be impacted by road lighting.

9.7.77 Shading: To investigate the potential impacts of the bridge shadow on the mudflat, three approaches were taken. First, a computer model was run to demonstrate graphically the location of the bridge shadow on the mudflat at hourly intervals during an entire day in January, April, July, and September. The objective was to determine whether any portion of the mudflat or seabed would be shaded during all hours of the day. This would not occur because the bridge crosses Deep Bay on a southeast-northwest bearing (approximately 145-325o compass bearing). The sun rises on the east side of the bridge and sets on the west side, thereby lighting both sides of the bridge at different times of the day. If the bridge crossed the bay on an east-west bearing (90-180o), areas directly beneath the bridge would be shaded at all times (Note: This situation prevails at the Lotus Bridge in Macau where herons and egrets were documented feeding adjacent to and beneath the bridge.). The model outputs demonstrated that the bridge shadow would affect areas directly beneath the bridge for periods ranging from 4 to 5 hours per day, but no area beneath the bridge would be shaded at all times during any day in any season of the year (see Figure 9.15). Because of the height of the bridge deck above the mudflat, either direct or indirect light would reach all portions of the mudflat and water surface or seabed during all hours of every day. Because the only light-sensitive organisms beneath the bridge are mangroves (and potentially seagrass, should seagrass colonise the mudflat beneath the bridge), and because no area beneath the bridge would be shaded at all times, we conclude that potential shading impacts are not a conservation concern for this project. Our second approach to determining potential impacts of shading was to visit the Lotus Bridge in Macau. The bridge was only recently completed (mid-2001), but mudskippers and algae were observed on the mudflat beneath the bridge. This was in spite of the fact that the mudflat was not properly restored following construction (construction debris remained and the mudflat sediments were not restored to a proper elevation and re-graded after being disturbed by construction equipment). Our third approach to determining potential impacts of shading was to investigate whether birds feed in areas beneath bridges. Field studies in Hong Kong demonstrated that herons and egrets feed on mudflats of the Kam Tin River beneath the Route 3 flyovers (Appendix 9A). The width of the two central 3-lane Route 3 flyovers is similar to that proposed for SWC, and two additional 2-lane flyovers run alongside the central flyovers. This is the site nearest to Deep Bay that is intertidal and is known to support herons and egrets. That ardeids feed on exposed mudflats beneath the Route 3 flyovers suggests that any impacts of shading are insignificant to ardeids and their prey.

9.7.78 Marine water quality - General water quality: Based on the predicted results in Section 7, the changes in water quality resulting from the construction of bridge piers and reclamation at Dongjiaotou were small. The differences in model predictions between Scenario 1 (the current Deep Bay) and Scenario 3 (Deep Bay with the bridge and the landing point reclamation) are almost indistinguishable at DM1, DM2 and DM3 (EPD's marine water monitoring stations) in all the time series plots. As can be seen in Figure 7.119, the absolute differences of the presented parameters (E. coli, SS, BOD, DO, UIA, TIN and salinity) between the two scenarios were much lower than the ranges of natural fluctuations of them.

9.7.79 Comparing the model predictions for Scenario 1 and Scenario 3 at DM1 which is the station closest to Mai Po and has the highest pollution level, the highest differences in BOD (0.294 mg/L), DO (0.173 mg/L), SS (2.74 mg/L), E. coli (1,870 count/100mL), UIA (0.0041 mg/L), TIN (0.157 mg/L) and salinity (0.046 ppt) were well within the natural fluctuations.

9.7.80 During the operation of the SWC bridge, there would be no discharge of effluent into Deep Bay from the bridge. The large amount of pollution loads entering Deep Bay as a result of increases in population and urbanisation in Shenzhen and Hong Kong is the most critical factor affecting the water quality in Deep Bay. Some parameters of the current water quality have exceeded the WQO standard. Based on the model predictions in Section 7.7, the SWC bridge and the reclamation at Dongjiaotou would only cause small changes in water quality conditions (<2.5%) in Deep Bay. For the SWC bridge alone, the changes were insignificant (<0.85%). Overall, the water quality changes would be within the ranges of natural fluctuations in the bay. It is therefore anticipated that the changes are not likely to cause adverse impacts to the marine ecosystem in Deep Bay. The impact is ranked as insignificant.

9.7.81 Marine water quality - Flushing rate: Obstruction of water movements could alter the tidal exchange rate of Deep Bay and could produce knock-on effects in sedimentation rates and water quality. Water quality impacts of the SWC on nature conservation areas in Inner Deep Bay were identified as a concern. To address this concern, hydrodynamic and water quality modelling were undertaken. Results indicate that once the alignment built, bridge piers by themselves would have little impact on instantaneous tidal flows (<1% change) and salinity patterns in Deep Bay, and no discernible impact on longer term residual flows and salinity fluxes, suggesting that potential operational impacts due to obstructed tidal exchange would be undetectable. Similarly, Crosslinks2 modelling predicted few or no far-field effects on water quality (Mouchel 1998). It was predicted that water movements and water quality in Deep Bay with the SWC in place would be similar to the baseline situation. Operational-phase effects of the bridge upon water quality were predicted to be insignificant at the large scale, particularly in terms of identified areas of conservation importance. It should be noted that due to the grid size used in the model, potential near-field effects such as scour near bridge piers could not be assessed. Very localised scour could occur in the immediate vicinity of the bridge piers, but water speeds would generally remain too low to erode existing sediment deposits. Any changes in bed level would take place at a very low rate and should not affect the survival of benthic fauna. Water quality modelling results support this contention by showing minor water quality changes in the operation stage of the project. Reclamation at the Shekou-side landfall has been included in the hydrodynamic and water quality modeling for Deep Bay. The impact is ranked as insignificant.

9.7.82 Marine water quality - Sedimentation: The presence of the SWC bridge piers to some extent may change the tidal flow patterns in the bay especially in the locations near the bridge alignment and the region landward from the bridge alignment (Inner deep Bay). Siltation and resuspension rates of sediment particles in Deep Bay may be altered as a result of the changes in hydrodynamic conditions leading to the changes in sedimentation and erosion patterns. The major concern of this impact is the sediment deposition on Mai Po mudflat.

9.7.83 It, however, should be noted that the baseline sediment deposition rate in the region near Shenzhen River outlet is rather high. According to the results of the simulation of sedimentation/erosion conditions in Deep Bay as presented in Section 7 of this report, most of the sediment particles discharged from the river would be carried by the tidal flows and would deposit in Mai Po and Ramsar Site increasing the sediment thickness in this region during the dry season (see Section 7.7.179). Mai Po located near the Shenzhen River outlet is currently being affected by this natural sediment deposition phenomenon (the average sedimentation rate up to about 28 mm/yr in Ramsar Site/Mai Po region, see Table 7.39 in Section 7).

9.7.84 The increased sedimentation rates due to the SWC bridge alone (Scenario3 vs Scenario 2) were very low. At all the indicator points, the bridge contributed to the increases in sedimentation rates of = 0.6 mm/yr. At Mai Po and Ramsar Site, the increased sedimentation rates due to effect from the bridge alone were very low, only about 0.1 mm/yr (see Table 7.38 in Section 7).

9.7.85 If both the bridge and the mainland landing point reclamation were considered (Scenario 3 vs Scenario 1), there would be some changes in velocity patterns and the exchange of flow in the inner region of the bay, mainly due to the reclamation. At Mai Po and Ramsar Site, sediment deposition rate may slightly increase (+0.3 to 0.5 mm/yr) (see Table 7.38 in Section 7) after the completion of the SWC. The cumulative impacts due to the present project and the Mainland landing point reclamation are low when compared to the natural conditions.

9.7.86 The existing sedimentation rates in Deep Bay were much higher than the small increases due to the SWC project. The natural processes would be the dominant factors in controlling the sedimentation and erosion in Deep Bay. The increase of sedimentation rate would be undetectable for the bridge alone (1 mm in 10 years), or for both the bridge and the landing point reclamation (3-5 mm in 10 years). The impact is thus ranked as insignificant.

9.7.87 Marine water quality - Road Runoff: Operation of the SWC would generate hard surface runoff containing oil, metals and other contaminants. This could affect water quality in Deep Bay and in any local watercourses affected by road drainage, with implications for freshwater and estuarine flora and fauna. The primary concern is Deep Bay ecology: persistent pollutants such as metals entering the bay could enter the food web and indirectly affect fauna of conservation concern such as waterbirds and dolphins. Impacts would be dispersed along the length of the bridge and would be long-term. Given the background levels of contamination in Deep Bay and the fact that vehicles using the crossing would remain within the Deep Bay catchment whether using the SWC bridge or one of the other 3 crossings. Increased traffic flows due to potential future economic growth would increase the volume of traffic crossing the bridge. However, this would also affect the 3 existing crossings as well, all of which are in the Deep Bay catchment. Impacts are ranked as minor and requiring mitigation.

9.7.88 Marine water quality - Chemical spillage: One of the key concerns on water quality impacts during the operation of the SWC is spillage of chemicals in case of vehicle accidents on the bridge. The types of chemical substances may include petrol, corrosive substances and toxic substances. Release of chemical substances may enter Deep Bay through the road drainage system causing a hazard to the marine ecosystem in Deep Bay.

9.7.89 Statistical data on traffic accident on major bridges in Hong Kong recorded by Transport Department from 1997 to 2002 showed that traffic accident rates ranged from 0.7 to 7.7 accident/year. These major bridges included Ap Lei Chau Bridge, Tsing Yi South Bridge, Tsing Yi North Bridge, Cheung Tsing Bridge, Ting Kau Bridge, Tsing Ma Bridge and Kap Shui Mun Bridge. The annual average traffic accident rates for the major tunnels including Cross Harbour Tunnel, Tate's Cairn Tunnel, Eastern Harbour Crossing, Lion Rock Tunnel and Western Harbour Crossing from 1997 to 2000 were in the range between 3.3 and 30 accident/year. The traffic accident rates for some of the major expressways including Tuen Mun Road, Kwun Tong Bypass, Island Eastern Corridor and North Nantau Highway were in the range between 27.3 and 255 accident/year.

9.7.90 The accident rates are related to the types of roads/highways, travelling distance and traffic flow. With reference to the past data, the recorded vehicle accident rates on bridges were not unusually high. The frequency of vehicle accidents on the proposed SWC bridge would be comparable to the accident rates of the major bridges in Hong Kong. It is expected that accident rates would be even lower for accidents causing spillage of chemical substances since there are special regulations and licenses for Dangerous Goods Vehicle.

9.7.91 For general vehicle accidents, which do not involve spillage of chemicals or dangerous goods, the potential environmental impact would only be due to leakage of fuel oil. It is however anticipated that oil spill events in relation to traffic accidents on the SWC bridge would only involve a small quantity of fuel. For example, the fuel tank capacity of a container truck is 400 litres. Since the spill would spread on the road surface, much of the spill would be retained on the road surface even leakage of fuel oil occurs. In case that the spill is released into the bridge drainage system, the road gullies could hold some of the spill (approximately 50 litres in each road gully, see Figure 7.105). The remaining quantity of spill, which would be released into the seawater or mudflat through the drainage pipes, would be small. The effect on the ecological system would not be significant and would be limited to a small area.

9.7.92 Although the spill incident for general vehicle accidents would not be as critical as that for accidents, which involve dangerous goods vehicles, a quick response to handle the accidents would minimise the potential impacts to the Deep Bay environment.

9.7.93 In the event of oil pollution at sea, Marine Department (MD) is the designated authority for the clean-up of oil. Other agencies or government departments will provide support to MD to response to any oil pollution. A Maritime Oil Spill Response Plan (MOSRP) has been developed by MD to deal with oil spill and their potential hazard to the Hong Kong waters. The main objective of the MOSRP is to ensure a timely and effective response to oil spillages and/or their potential treats in the Hong Kong waters.

9.7.94 The oil spill response is categorised into 3 tiers. Tier 2 covers the oil spill up to about 500 tonnes. In case of a major accident with a large amount of oil spill, immediate responses from MD would effectively control the oil spill and potential damage to the sensitive areas in Deep Bay would be minimised. It is likely that oil spill from general vehicle accidents would not be a critical issue during the operation of the SWC bridge.

9.7.95 However, in case of release of chemical substances into Deep Bay in a single accident, these substances would be detrimental to the marine ecosystem in Deep Bay. Accidents, which involve dangerous goods vehicles carrying a large amount of chemicals would be a concern.

9.7.96 Spillage of toxic chemicals into Deep Bay due to traffic accidents involving Dangerous Goods Vehicles on the SWC bridge would cause impacts to Deep Bay ecosystem. Organic chemical substances may exist in seawater or adhere to sediment. Though mortality of marine organisms might not be found instantly, due to their persistence, bio-accumulation through food chains would be possible and a higher concentration might be resulted inside the bodies of animals at the top level of the food chains, such as birds. Inorganic toxic substances, though the persistence of some of them might be lesser than that of organic substances, could cause impacts of larger scale in a short period of time. Death of marine organisms might be caused.

9.7.97 Though long-termed ecological consequence might be caused by the chemicals, given the episodic nature of accidents and the mitigation measures detailed in Section 7 of this report, the chance of chemicals entering Deep Bay marine ecosystem is remote. The impact is thus ranked as minor, and mitigation measures are required (see Section 7).

9.7.98 Air pollution: Traffic on the bridge would introduce a new source of air pollution into the Ngau Hom Shek and Ha Tsuen areas. Impacts to flora and fauna are ranked as insignificant based upon the air quality assessment for the bridge (see Air Quality chapter).

9.7.99 Table 9.7.3 summarises the potential impacts of operation of the SWC.

Table 9.7.3 Operation-phase Impacts of the SWC

Cumulative Impacts

9.7.100 Cumulative impacts of the SWC project could be divided into short-term or temporary impacts, and long-term or permanent impacts. Major concerns would be those resulted from the water quality and sedimentation impacts of the present project, the Mainland section of the SWC, Deep Bay Link, and other projects in the Deep Bay area.

9.7.101 Short-term impacts would be resulted from construction works: e.g. construction noise, disturbance and construction site runoff. The potential of temporary cumulative impacts will be depended upon the construction programmes of related projects in the Deep Bay catchment.

Cumulative Construction Impacts with Other Projects

9.7.102 SWC Mainland section: The SWC Mainland section would be constructed concurrently with the present project. It is anticipated that the construction impacts from the SWC Mainland section would be at a smaller magnitude, due to the shorter length. Impacts from this would be mainly the temporary sedimentation and pollution of Deep Bay water due to construction of piers.

9.7.103 The Mainland EIA (Shenzhen Bay Bridge) indicated that the bridge foundation would be construction using bored piles. Bored pile casing would be driven into the seabed and would confine the sediment within the casing. Release of sediment and pollutants during sediment dredging was expected to be not significant. The wastewater generated from the bored pile construction would be treated for sediment removal. The treated effluent would be reused in the piling process. Based on the construction method presented in the Mainland EIA, it is considered that the construction of bridge foundation would not cause significant cumulative water quality impacts and marine ecological impacts with the SWC project.

9.7.104 SWC landing point: Reclamation on the Hong Kong side would not be required for the SWC project. The only required reclamation is the landing point at Dongjiaotou on the Shenzhen side. A review of the Mainland EIA Report on the SWC Reclamation and Foundation Treatment Engineering (Reference 2) was conducted. The report presented that the potential water quality impacts would be mainly associated with the reclamation activities. The Mainland authorities confirmed that the reclamation at Dongjiaotou would be conducted behind seawalls and would commence in 2002. The overall construction period was expected to be approximately 22 months. External seawall would be constructed along the perimeter at the early stage of the reclamation and be completed within the first 6 months of the overall construction programme. The seawall strengthening and construction to enclose reclamation works at Dongjiaotou for the Shenzhen reclamation would be completed prior to commencement of construction of the SWC bridge in August 2003. All the reclamation activities would be carried out behind the seawall and there would be no overflow of water from the enclosed reclamation site to Deep Bay when carrying out the filling activities. Filling behind the seawall would continue for the remaining 16 months thereafter, but sediments would be confined to the area within the seawall. The whole reclamation site would be divided into a number of cells. Discharges of seawater would be from an active cell to the adjacent inactive cells. The inactive cells provide a quiescent environment for settling of sediment particles. The seawater at the last cell would be pumped out from the confined reclamation site to the sea. After settling of sediment particles, the seawater pumped out from the site is not likely to contain high concentrations of suspended solids. Thus there would be no potential for sedimentation of Deep Bay waters during the filling process.

9.7.105 As the proposed SWC project would commence in August 2003, there would be no overlap of the bridge construction project with the seawall construction project. The completion of external seawall at the landing point before the SWC project would minimise the accumulation of water quality impacts from the filling process of Shenzhen reclamation and the SWC project. Therefore, no significant cumulative impacts would result from these two projects.

9.7.106 It was also confirmed with the Mainland authorities that there would be no sand dredging from Deep Bay for reclamation. The source of the fill materials for reclamation would be mainly from land and import of marine sand fill for reclamation might be required. It is expected that the water content for these types of fill materials would be low and discharge of sediment-laden flow from the reclamation site can be avoided.

9.7.107 The potential water quality impacts from concurrent construction of SWC bridge piers of the Hong Kong and Mainland sections and reclamation at Dongjiaotou have been presented in Section 7.7.63 to Section 7.7.68. There were no exceedances of WQO and Mainland Category 1 standard for SS at all the identified water sensitive receivers. Mitigation measures of the Hong Kong section of the SWC, mitigation measures in the Mainland EIA, and the Environmental Management and Audit Plan in the Mainland EIA, to minimise the water quality impacts arising from the Hong Kong section, Mainland section and landing reclamation have also been detailed in Section 7 of this report. It is anticipated that the potential water quality impacts would not be significant provided that the above-mentioned conditions could be met. There would not be cumulative impacts from the three items of works.

9.7.108 Deep Bay Link: The construction programme for the Deep Bay Link project will be implemented concurrently with the SWC project. Deep Bay Link will be constructed concurrently with the SWC bridge and is expected to be in operation by end of 2005. All the construction works for the Deep Bay Link project would be carried out from a land-based operation. Components of the two projects could overlap where Deep Bay Link joins SWC. The Deep Bay Link project impacts would mainly come from temporary pollution of Deep Bay (site runoff) due to construction.

9.7.109 Impacts in the terrestrial and freshwater habitats would be caused by the DBL project. Because the SWC field studies also covered an area extending 330 m inland along the alignment, construction phase impacts and mitigation proposals are briefly discussed in the paragraphs below. Readers are referred to "Final EIA Report. Agreement No. CE109/98, Deep Bay Link Investigation and Preliminary Design" (Arup 2002) for details of the impact assessment.

9.7.110 Construction phase - Temporary habitat loss - Terrestrial: Construction of the bridge landing would destroy and fragment abandoned agricultural, village, shrubland and grassland habitats at Ngau Hom Shek. Temporary terrestrial habitat losses, within the SWC study area but under Deep Bay Link jurisdiction, would be 4 pair of piers and the associated works area, i.e. a 50 m wide impact area along the proposed 330 m length of the DBL roadway on land, a 330m x 50m area = 1.65 ha. Approximately 1.65 ha of grassland, shrubland, farm and residential land would be lost during construction. Though the limited ecological value and the small extent of areas to be affected, loss and fragmentation of these habitats were ranked as moderate impacts due to the impact on an egretry. Ngau Hom Shek East stream drains part of the alignment area, and would be affected by the construction project. The stream has been diverted from its original channel, and otherwise modified. A wetland compensation plan was proposed to compensate for the loss of fishponds under development by the Deep Bay Link project.

9.7.111 A small egretry at Ngau Hom Shek (7 nests counted in 2001 and 10 nests in 2002) lies under the alignment and would be destroyed by the bridge landing. This egretry never supports more than 2% of all nesting pairs in HKSAR since its discovery in 1998. The egretry moved from the former location where it had been discovered in 1998 to a nearby site in 2001. Local egretries, indeed, frequently move for unidentified reason. Because of the mobility of the Ngau Hom Shek egretry like others in HKSAR (e.g. Tsim Bei Tsui, Shan Pui River, Au Tau, and others) and the small number of nests involved, this is ranked as a minor impact and mitigation is required.

9.7.112 It is recommended that the existing trees and bamboos used by the egrets are transplanted to the proposed wetland compensation area after the breeding season in 2002 has finished (September) and before the breeding season begins in 2003 (February at the latest) to avoid unnecessary mortality of ardeid birds when construction works begin and provide a potential alternative breeding site for ardeids.

9.7.113 Other temporary habitat losses in Deep Bay Link would occur in the part of the project area far away from the SWC project boundary and have been addressed in the EIA study for Deep Bay Link (Arup 2002).

9.7.114 As the habitat types affected in the SWC project and the Deep Bay Link project would be different, and the impacts would not extend beyond their site boundaries, no cumulative impact would be caused.

9.7.115 Construction phase - Disturbance - Terrestrial: Terrestrial noise and disturbance from construction was discussed in Deep Bay Link EIA study (Arup 2002) and ranked as minor. The alignment of Deep Bay Link is an extension of that of the SWC. The work fronts of these two projects would thus spread over a long distance. Due to the localised nature of construction noise and disturbance, disturbance impacts would not extend beyond the project boundaries and no cumulative impacts would be caused.

9.7.116 Construction phase - Marine water quality - Site Runoff: Release of construction site runoff into Deep Bay from terrestrial works areas of DBL could also contribute to water quality degradation and might cause cumulative impacts with the SWC project. Pollutants that might be discharged include fuels, solvents, lubricants, and sewage. Construction site runoff can be effectively controlled through the implementation of suitable mitigation measures, e.g. provision of site drainage systems and sedimentation facilities, routine monitoring of the effluent discharge quality and environmental audit. The other issues including generation of wastewater and sewage, and accidental spillage of toxic substances during the construction period can also be minimised or controlled by providing chemical toilets and/or wastewater treatment facilities, off-site disposal of wastewater/sewage and establishment of a spill response plan. The potential to have cumulative water quality impacts due to the Deep Bay Link project would be low.

9.7.117 Water Supply to Hung Shui Kiu, Kwu Tung North, Fanling North and Ping Che/Ta Kwu Ling New Development Areas: This WSD project is tentatively scheduled to commence in around late 2005 or early 2006, and to complete by 2009. The construction programme for this WSD project would overlap with the SWC construction programme.

9.7.118 The proposed pipe section for the project includes a 900mm diameter salt water main, which would be laid along the Deep Bay Road passing through Fung Kong Tsuen Road to Hung Shui Kiu NDA. Part of the section would fall within the SWC site boundary.

9.7.119 Excavation of trenches would be required during the construction of the salt water main. The potential water quality impacts that may arise from this WSD project would mainly be construction site runoff. A rainstorm may wash away the excavated materials to Deep Bay. The impact could be minimised if suitable mitigation measures are implemented when carrying out the excavation activities. Guidelines for the handling and disposal of construction discharges provided in ProPECC Note PN1/94 on Construction Site Drainage should be adopted to avoid water quality pollution. Digging of trenches should be carried out in short sections. After finishing a section of works, trenches and holes should be immediately back-filled to minimise the inflow of rainwater during rainstorms.

9.7.120 A salt water service reservoir is also proposed under this WSD project. The tentative location would be near the Fung Kong Tsuen Road at hillside of Fung Kong Tsuen. This proposed salt water service reservoir is located outside of the works limits of SWC.

9.7.121 The scale of this WSD project is expected to be small. It is anticipated that there would be no additional impact induced by this WSD project after the implementation of suitable mitigation measures.

9.7.122 Water supply to Sludge Treatment Facility at Tuen Mun: A fresh water main is proposed to provide water supply to the proposed sludge treatment facility near WENT landfill site. This fresh water main would pass through Nim Wan Road, Lau Fau Shan Road, Tin Wah Road and Tin Ying Road and would connect to an existing fresh water main in Tin Shui Wai. The tentative commencement date of this project would be in 2005 and the completion date would be in 2008.

9.7.123 The key issue that may cause cumulative impacts with the SWC project is construction site runoff. Digging of trenches would generate exposed soils, which may be a potential pollution source to the Deep Bay waters. The ProPECC Note PN1/94 on Construction Site Drainage should be adopted to minimise the potential impact. In addition, good management practices could ensure that the potential impact to the nearby water body is minimal. It is likely that the overlapping of this WSD project with the SWC project would not cause unacceptable cumulative impacts in Deep Bay.

9.7.124 Yuen Long and Kam Tin Sewerage and Sewage Disposal - PWP Item No. 4215DS: The tentative programme for commencement of the project is scheduled in May 2005 and for completion in August 2007. This DSD project involves the provision of rising mains and gravity sewers at Tin Ying Road, Tin Wah Road and Lau Fau Shan Road. Similar to the projects proposed by WSD, construction site runoff would be the key issue that may cause cumulative impacts with the SWC project. Implementation of the guidelines recommended in the ProPECC Note PN1/94 on Construction Site Drainage could control the release of construction site runoff and minimise the other potential water pollution issues associated with the construction works.

9.7.125 The boundary of this project covered an extensive area from Pat Heung to Kam Tin River. Due to the localised nature of disturbance impacts, no cumulative disturbance impacts on Ramsar Site from the SWC project and this project would be caused.

9.7.126 Upgrading & Expansion of San Wai Sewage Treatment Works (STW) and the Expansion of Ha Tsuen Pumping Station: The construction works for this project would commence in around 2004. The project is planned to expand the existing facilities at San Wan STW and Ha Tsuen Pumping Station. The treated effluent would be discharged via the NWNT effluent tunnel. An emergency discharge culvert from San Wai STW to nearby drainage channel would be constructed to provide an alternative discharge route for the treatment works.

9.7.127 An EIA study is being conducted for this project. All the construction and operational phase impacts would be addressed in that EIA. The construction works would be carried out from a land-based operation. The locations of the construction sites for this project are away from Deep Bay. Runoff from the construction sites may enter the local stream courses and/or Tin Shui Wai Drainage Channel before entering Deep Bay. With all the mitigation measures in place to control water quality pollution from the construction sites, the potential cumulative impacts with the SWC project would be low.

9.7.128 Hung Shui Kiu New Development Areas (HSK NDA): The construction works for this development project would be in 2004 and the expected completion date is in 2008. The site limit of SWC is far away from the HSK NDA and there would be no conflict between the two projects. Environmental monitoring and audit would be implemented for the HSK NDA project. It is not expected that there would be adverse cumulative impacts generated from these two projects.

9.7.129 No cumulative disturbance impacts would be expected from the SWC project and this project as the site area of this project is sheltered from the Ramsar Site by the existing Tin Shui Wai new town.

Cumulative Operation Impacts with Other Projects

9.7.130 The long-term impacts would result from changes in hydrodynamic conditions and pollution loading. Their potential will depend upon the nature of those projects.

9.7.131 SWC Mainland section and landing point: Impacts from the SWC Mainland section and landing point project would include:

· permanent loss of 0.09 ha [= 30 pairs x 2 piers/pair x (6m x 2.5m)] of subtidal seabed at pier locations;
· permanent loss of ~150ha of subtidal and intertidal seabed at landing point at Dongjiaotou Shekou;
· Reduction in the size and alteration in the shape of Deep Bay, and the resulted implications for hydrodynamics, water quality and marine ecology.
· permanent increased levels of light, traffic flow and air pollution along the bridge; and
· permanent potential for increased long-term pollution of Deep Bay waters due to road runoff.

9.7.132 Scenario 3 in the water quality modelling had taken into account the Mainland section and the landing point of SWC. The cumulative operation impacts on water quality had been addressed in the sections of operation phase impacts above. It is anticipated that other impacts, such as lighting and collision from the SWC Mainland section will be similar in nature, but at a smaller magnitude, due to the shorter length in Mainland section and the longer distance from Mai Po.

9.7.133 Deep Bay Link: Deep Bay Link is expected to be in operation by end of 2005. Components of the two projects could overlap where Deep Bay Link joins SWC. Permanent impacts of key interest are those associated with habitat loss. Cumulative losses of specific habitat types are discussed below. The Deep Bay Link project impacts would include:

· permanent loss of the Ngau Hom Shek egretry, accounting for about 10 nests of herons and egrets;
· permanent increased levels of light, human activity and air pollution along the highway alignment; and
· permanent potential for increased long-term pollution of lowland streams and Deep Bay waters due to road runoff.

9.7.134 Operation phase - Permanent habitat loss - Terrestrial: For the purpose of operational phase impact assessment we also assumed the permanent loss of land on the HKSAR side to be equivalent to the cross-sectional area of the columns, which is calculated above. There are 4 pairs of piers of DBL section on terrestrial area occupying about 120 m2. The loss is 0.012 ha and the impact is insignificant. A compensatory wetland was, however, proposed to compensate for the habitat loss from the Deep Bay Link project as a whole, as given in "Table 7.33 Details of proposed DBL wetland compensation area." of DBL Final EIA Report (Arup 2002)(also see Figure 9.16A & Table 17.1 of this report).

9.7.135 Operation phase - Fragmentation - Terrestrial: Some of the bird species recorded flying over the surveyed bridges are inhabitants of terrestrial habitats (e.g., Chinese Bulbul) and occur in upland habitats in the Study Area. Because these species flew over bridges with no observed adverse impacts we predict that the SWC bridge will not be a barrier to movement of birds in terrestrial habitats. The impact is ranked as insignificant for the overlapped portion between the two projects.

9.7.136 Reduction of impacts by keeping construction activity strictly confined was considered adequate as a mitigation measure for most habitat loss. Compensatory replacement of lost habitats on-site was recommended in spite of the relatively small areas affected and their low to moderate value. Compensation for loss of shrubland should take the form of shrubland or woodland (i.e. more advanced successional stages).

9.7.137 Operation phase - Disturbance - Terrestrial: Disturbance would not be expected to be significant for conservation areas in Inner Deep Bay, since the nearest of these areas (the Ramsar Site) would be 5 km from the bridge. Terrestrial noise and disturbance from vehicles using the SWC would also be unlikely to affect bird activity at the Pak Nai SSSI (2.5 km away). Some species (e.g., Blue Rock Thrush Monticola solitarius, Crested Myna Acridotheres cristatellus), nest in the drainage systems on the underside of the bridge deck of the Route 3 flyover. Bats roost in bridges that offer suitable roost sites in spite of traffic noise and disturbance on the bridge deck. A number of local egretries are located near busy traffic (e.g., Mai Po Village SSSI egretry, Mai Po Loong egretry, former Tai Po Market egretry), despite of the noise and disturbance. A similar result would be expected for bird and other wildlife use of fishponds near the SWC bridge. Black-faced Spoonbills were not recorded feeding in fishponds in the study area, thus any unforeseen disturbance to fishponds would not affect BFS. Potential disturbance impacts are ranked as minor and noise reduction measures such as screen planting are recommended.

9.7.138 "Yuen Long and Kam Tin Sewerage and Sewage Disposal" and "Upgrading & Expansion of San Wai Sewage Treatment Works (STW) and the Expansion of Ha Tsuen Pumping Station" would have positive effects on the water quality in Deep Bay. Sewage would be more effectively collected and treated in the STW in Yuen Long and San Wai, and then dispose the effluent in Urmston Road. These two projects could reduce non-point pollution input within the Deep Bay catchment.

9.7.139 The majority of the area for Hung Shui Kiu New Development Areas (HSK NDA) is currently wasteland or abandoned agricultural lands. Given the highly disturbed nature of the area, it is a potential source of sediment in the flow in Tin Shui Wai Drainage Channel and also Deep Bay during wet season. After the completion of this project, the surface runoff from the area would be expected to increase in quantity, but decrease in the sediment carried.

Cumulative Effects of SWC with Other Projects

9.7.140 Table 9.7.4 lists proposed, approved and existing projects that could cause cumulative effects if constructed simultaneous with SWC.

Table 9.7.4 Projects Having Potential Cumulative Effects with the SWC Bridge

Summary

9.7.141 For cumulative impacts, Section 4.3.3 in EIAO-TM has listed out three circumstances for cumulative impacts:

· the impacts arising from the project are predicted to extend beyond the boundaries of the project or over a long period of time;
· there may be interactions between the environmental impacts of the project, affecting the sum total of its environmental impacts; or
· there may be interactions between the environmental impacts of the project and the environmental impacts of other developments, resulting in accumulation of impacts and affecting the sum total of their environmental impacts.

9.7.142 In the SWC project, the majority of ecological impacts, including temporary and permanent habitat loss, fragmentation, construction disturbance and collision, would be localised in nature and would not extend beyond the project boundary. The only ecological impacts might have influences beyond the project boundary would be those of marine water quality such as flushing rate and sedimentation rate. Since the assessment area of water quality covered the entire Deep Bay WCZ, the influences from marine water quality changes on areas outside the project boundary have been addressed in Water Quality Assessment.

9.7.143 No interaction between the environmental impacts of the present project, which might affect the sum total of the impacts, was found.

9.7.144 For the interactions with impacts from other developments, the majority of other projects in Deep Bay area would be land-based, including Deep Bay Link. Moreover, the construction of the majority of other projects would not overlap, or would only overlap in a short period of time with the SWC construction. Only Deep Bay Link, the Mainland section, and the landing point reclamation of the SWC would be constructed concurrently with the present project.

9.7.145 For the disturbance impacts during construction, given the localised nature of disturbance impacts, there would be no cumulative disturbance impacts. The three major projects proceeded with the present project, i.e. Deep Bay Link, landing point reclamation and the Mainland section of SWC, would locate further away than the SWC from the Inner Deep Bay which harbours ecologically important areas such as Ramsar site. The Hung Shui Kiu NDA is located at a distance similar with that of the SWC to Mai Po, but is sheltered by the existing Tin Shui Wai new town.

9.7.146 Other than site runoff, Deep Bay Link and other land-based projects would have little potential to produce cumulative impacts with the present project in terms of marine water quality. Mitigation measures to control site runoff would be provided in those land-based projects and thus no cumulative impacts on water quality would be expected.

9.7.147 For the Mainland section of the SWC, bored pile method would be used for the bridge pile construction, while the seawall construction of the landing point reclamation would be finished prior to the filling and the commencement of the present project. No cumulative impacts on water quality during construction would be expected.

9.7.148 During operation phase. The potential for cumulative impacts resulted from land-based projects would be very limited. As the habitat types affected by the land-based projects would be different with those by the present project, there would be no accumulation of habitat loss and no influence on the sum total of habitat loss.

9.7.149 The landing point reclamation and the Mainland section of SWC bridge would cause ~150ha and 0.09 ha seabed loss respectively. This ~150ha would constitute a loss of about 1.3% of Deep Bay (about 11,500 ha). This impact was considered acceptable. Even if considered together with the seabed loss from the present project, i.e. 0.2196 ha (0.1956ha in subtidal zone + 0.024 ha in intertidal zone), the total seabed loss would be only about 1.3% of Deep Bay. Furthermore, there would be no influence on the sum total of habitat losses from the three projects.

9.7.150 Scenario 3 in the water quality modelling had taken into account the Mainland section and the landing point of SWC. The cumulative operation impacts on water quality had been addressed in the sections of operation phase water quality impacts. So there would be no additional cumulative operation impacts with the SWC.

9.7.151 To conclude, the only cumulative impact identified was an additional 1.5km² seabed loss. The loss was insignificant to Deep Bay. Even including the seabed loss from the SWC project, the cumulative seabed loss would be only about 1.3% of Deep Bay. The cumulative impacts from the present project would be acceptable.

9.7.152 The preceding analysis indicates that the SWC bridge would have insignificant to minor ecological impacts, both individually and cumulatively with other projects. The following section outlines mitigate measures, and assesses the acceptability of residual impacts.

9.8 Mitigation of Adverse Environmental Impacts

9.8.1 This section outlines potential mitigation measures for those impacts identified in Section 5 that would require mitigation. Mitigation measures were developed in accordance with the guidelines of the EIAO-TM (Sections 4.3.1d and 5.4), the mitigation policy laid out in the TC and Paragraph 6.19 of the Brief: "Proposals of effective mitigation measures (including possible off-site compensation as required under PELB Technical Circular No. 1/97 and Works Bureau Technical Circular No. 4/97) to reduce ecological impacts to acceptable levels should be made. These measures should be described in terms of their scope, programme, feasibility and financial implications during the construction and operation of the SWC". The mitigation measures outlined in this section are those predicted to be required to reduce ecological impacts to acceptable levels, based on currently available project information. The mitigation measures proposed for SWC should be reviewed when detailed design information is available to ensure that the measures proposed are appropriate and necessary.

9.8.2 The fundamental criteria for success in mitigation measures are:

· they achieve the intended goal; and
· they are feasible based upon engineering, administrative and economic concerns.

9.8.3 The EIAO-TM (Annex 16) and the TC require that mitigation of ecological impacts be sought in the following order of priority: (1) avoid, (2) minimise, (3) compensate on-site and (4) compensate off-site. At each stage, residual impacts should be re-assessed to determine whether there is a need to proceed to the next stage of mitigation.

9.8.4 This section also outlines the likelihood of residual ecological impacts following completion of all mitigation measures, and assesses the significance and acceptability of these residual impacts. As with the impact assessment above, residual impacts are quantified where possible. The consultants' understanding of "acceptability" draws upon HKSAR legislation, standards and guidelines and upon internationally accepted practices in conservation biology.

Design Phase Considerations

9.8.5 Location selection: In terms of avoidance, the Study Brief states that the project should avoid impacts on "Nature Reserves, the Ramsar Site, Sites of Special Scientific Interest, the Sha Chau and Lung Kwu Chau Marine Park". Identified areas of conservation importance within or near the study area include: Sha Chau and Lung Kwu Chau Marine Park; SSSIs (Mai Po Marshes, Mai Po Village, Inner Deep Bay, Tsim Bei Tsui, Tsim Bei Tsui Egretry, Pak Nai, Lung Kwu Chau, Tree Island and Sha Chau); the Ramsar Site; Mai Po Nature Reserve; and the Neilingding-Futian National Nature Reserve (China). The Brief further states that the project should avoid impacts on "other ecological sensitive areas that could be identified in the area". Field surveys have been undertaken to identify such areas (Table 9.4.1). Based upon information from literature review and field surveys, it was found in the assessment that the current location of the Shenzhen Western Corridor would cause the least impact to Deep Bay. The current location is 6km from Mai Po Marsh Nature Reserve, 7km from the mouth of Deep Bay, and 3.5km from Ha Pak Nai. The potential impacts on recognised sites of conservation importance would be higher if the corridor location was further northward (potential impacts on Mai Po), or further southward (potential impacts on Chinese White Dolphin). The current location of SWC is thus considered the most ecologically acceptable if a non land-based western corridor is needed.

9.8.6 Landing point selection: The most important form of mitigation, avoidance, has already been pursued through consideration of three alternative sites for the bridge landing. The Ngau Hom Shek was determined to be the least damaging ecologically and the most preferred all round (see Section 4 of this report). No fishpond would be resumed for the SWC project. For details of impacts on terrestrial habitats from Deep Bay Link please see "Final EIA Report. Agreement No. CE109/98, Deep Bay Link Investigation and Preliminary Design" (Arup 2002).

9.8.7 Option selection: Tunnel option was found to be less ecologically acceptable due to the need of large scale dredging during construction and the higher reduction o flushing rate during operation.

9.8.8 Several design features of the bridge could effectively minimise ecological impacts. Details are discussed below.

9.8.9 Increase pier spacing: Mouchel (1999) evaluated a bridge built on piers at 50 m intervals, and requiring some 106 piers. In the initial design phase of this project the SWC project team recommended increasing the spacing of piers to 75 m to reduce the number of piers, and thereby create more open space beneath the bridge, which was found acceptable by Hong Kong and Mainland on engineering grounds. This reduced pier numbers from 106 pairs to 70 pairs, thereby avoiding impacts of 36 pairs of piers. The effect of this change is modelled in Figure 9.16a and b.

9.8.10 The potential for the bridge to be a physical barrier to bird movements up and down the south shore of Deep Bay was addressed by this feature.

9.8.11 This reduced pier numbers from 106 pairs to 70 pairs, thereby avoiding impacts of 36 pairs of piers on subtidal and intertidal habitat. Both the area of permanent loss and temporary loss are reduced by 50%. The disturbance to intertidal habitat is also reduced as less disturbance source points on the mudflat surface.

9.8.12 Submerged pile caps: The pile caps for typical piers measure 8.5 x 8.5 m. Pile caps can be located either within the seabed mud or at the seabed surface. To avoid subtidal and intertidal seabed losses of 144.5 m2 at each pair of piers the project team recommended constructing pile caps beneath the seabed surface. The resulting net loss at typical piers would be <15 m2 (cross-sectional area of pier column), resulting in conservation of >130 m2 of seabed at each of 70 pairs of piers (>0.9 ha total).

9.8.13 Cable -stayed structure: The intertidal zone was identified early in field studies as the area of most intensive bird activity. Birds use the near-shore intertidal zone as feeding habitat and as a movement corridor. To accommodate bird use of the area an initial design proposal called for construction of a cable-stayed segment of the bridge to span over the mangroves and the near-shore intertidal zone, a distance of some 200 m. While such a bridge would have minimised obstruction to movement beneath the bridge, the cables above the bridge deck could have blocked bird flight over the bridge. To avoid such an outcome the project team settled on typical spans across the mangrove and mudflat, thereby avoiding the potentially adverse impacts of bridge support cables in the intertidal zone.

9.8.14 Bridge deck height: Most birds observed in Macau flew across Lotus Bridge at a height below 15m. Birds were also observed flying below or above bridges of height of 16 m in Hong Kong. The height of the SWC bridge is sufficient enough for birds flying across. In addition, the distances between pillars of the SWC bridge is wider than those of any bridges studied in Hong Kong or Macau. There is sufficient space for birds to fly below the SWC bridge.

9.8.15 Power line: Deep-coloured and thin in diameter, power lines were found having potential to cause bird kills during literature review. To prevent this impact, no power lines would be suspended above the bridge deck.

Table 9.8.1 Considerations in the Design of the SWC and the impacts to be minimized.

Construction Phase Mitigation Measures

9.8.16 The Crosslinks2 EIA suggested that "destruction and fragmentation of seabed habitat in Deep Bay could be mitigated by creating "artificial reef" habitats at suitable bridge piers, by facing piers with rip-rap or other materials which could provide shelter for small marine animals without compromising the function of the pier." Based upon the current concern for maintaining the existing tidal exchange rates and volumes, any mitigation measure that would tend to slow or impede tidal exchange is now considered undesirable. Therefore the development of artificial reefs at select bridge piers will not be pursued.

9.8.17 Temporary habitat loss - intertidal: Like-for-like compensation is provided for the intertidal mudflat loss. The area within the 50m works area will be restored from oyster beds to mudflats to mitigate the temporary and permanent loss of intertidal habitat caused by the pier construction sites and the piers. Oyster beds would be removed before the commencement of construction works. This area should be inspected for the compliance of clearance. Beside good working practices taken during construction to prevent unnecessary disturbance on mudflats, all wastes and construction materials must be cleared after completion of construction to guarantee the restoration of the mudflats within the works area. The works area boundaries for the project within the mudflat should be marked to ensure that work crews and equipment confine all construction activities to the designated works area. Markings should be readily visible, and should be replaced immediately if damaged. Construction materials and wastes, or equipment must be cleared from the mudflats after the construction period. The mudflat must be restored to its original low and smooth profile.

9.8.18 Currently the oyster beds in Ngau Hom Shek extend from the edge of mangroves to several hundred metres seaward. The mudflat area beneath the bridge and 50m of either side will be cleared as marine works area for construction works. Oyster farming will not be allowed within this area since then. This will clear an area of mudflat about 8.34 ha (139m x 600m). The net increase of clear mudflat area will be at least 7ha even considering the loss due to the bridge piers. Because seagrasses are relatively quick to exploit suitable habitats, this species will be expected to recolonize on the mudflats of better conditions.

9.8.19 Horseshoe crab: As noted in Section 9.4 of this report, horseshoe crab numbers are low because of over-exploitation rather than habitat loss in Deep Bay. Juvenile crabs found during field surveys indicate that crab reproduction in Deep Bay continues. The two juvenile horseshoe crabs found were both at Ngau Hom Sha. During the survey period (August 2001 - June 2002), the mudflat in Ngau Hom Shek, i.e. the bridge landing point, has been progressively occupied by oyster cultches since September 2001. The physical occupation of the mudflat area by oyster cultches, the placement of oyster cultches and other activities of oyster farmers probably limited utilization of the mudflat by juvenile horseshoe crabs. Oyster farming has been practised on the mudflat near the proposed landing point for many years. The landing point is thus not likely to be a regular nursery area for horseshoe crabs. The area of seabed affected by construction of the bridge piers is insignificant in comparison with the total seabed area of Deep Bay. Therefore bridge construction is not predicted to cause habitat loss that would reduce horseshoe crab survival or abundance in Deep Bay. The impact is ranked as insignificant. No mitigation is required.

9.8.20 As mentioned above, the mudflats in Ngau Hom Shek from the edge of mangroves to several hundred metres seaward were occupied by oyster beds. The mudflat area beneath the bridge and 50m of either side will be cleared as marine works area for construction works. Oyster farming will not be allowed within this area since then. This will clear an area of mudflat about 8.34 ha (139m x 600m). The net increase of clear mudflat area will be at least 7ha, even considering the loss due to the bridge piers. Seagrass is expected being able to colonising the re-exposed mudflats quickly. With the new colonised seagrass beds, the mudflats would be a more suitable habitat for horseshoe juveniles than it was.

9.8.21 Seagrass loss: Before the commencement of construction works, any seagrass beds within the 50m works area boundaries should be marked by visible markings and their total extent will be calculated. An area of exposed mudflat of the equal size will be identified in Pak Nai. Seagrass together with the sediment underneath will be divided into plugs of practical size, removed from Ngau Hom Shek and relocated to the identified area in Pak Nai. The surface of the plugs should be levelled with surrounding sediment at the relocation site. Relocated seagrass plugs should be monitored quarterly for survival and growth during construction phase.

9.8.22 Mangrove loss: The works area boundaries within the mangal at the shoreline at Ngau Hom Shek should be marked to ensure that work crews and equipment confine all construction activities to the designated works area. Markings should be readily visible, and should be replaced immediately if damaged. Number of mangrove seedlings to be planted and location of planting should be determined during the design and construction stage of the project. One set of piers would be constructed in the mangrove plantation at Ngau Hom Shek. This would cause a temporary loss of some 0.25 ha of mangroves (50 x 50 m area; mainly Kandelia candel), and a permanent loss of 30 m2 of mudflat (column cross-section area = 6 x 2.5 m = 15 m2 x 2 piers = 30 m2). To replace mangroves that must be destroyed in the construction process, new mangroves would be planted at suitable areas at or near the site of impact (Figure 9.17). Mangroves would be planted using locally collected propagules (droppers) that are available in later winter through spring seasons. Planting would take place after all construction works are completed, all construction equipment and materials and all rubbish have been removed, and the mudflat has been restored to its original contour. Because the conservation priority at Ngau Hom Shek is mudflat for use as foraging habitat by waterbirds, and because mangrove plantation conflicts with achieving this objective, propagules would be planted only in those areas where trees were destroyed. Planting density would be 1 propagule per m2. This high planting density would account for 50% mortality of planted droppers (higher than expected for K. candel; see Dahmer et al. in review). Monitoring specifications are included in the EM&A manual to ensure that propagules would be replanted if the original plantation fails to achieve the desired result.

9.8.23 Black-faced Spoonbill: Though no mitigation measure would be required for the insignificant loss of their peripheral feeding habitat (0.139 ha, or 0.24 ha in worst case scenario), Black-faced Spoonbill would be benefited from the additional enhancement measure in Mai Po as detailed in Section 9.9 below. It was estimated that 24.3 ha core feeding habitat of BFS would be enhanced.

9.8.24 Marine water quality: Sediment and pollutant resuspension would be avoided through construction methods including use of sheet-piling to surround pier works areas and use of bored pilings within casings for bridge piers. These measures are considered adequate to avoid sedimentation and pollution during pier construction. Closed-grab dredges should be employed where dredging is required. For works on land-based sites, standard site runoff control measures should be established and strictly enforced to ensure that contaminated or silt-laden runoff does not enter Deep Bay. Earth-moving should be scheduled as far as possible outside the rainy season.

9.8.25 The following Table 9.8.2 summarises measures proposed to mitigate construction-phase impacts of the SWC.

Table 9.8.2 Mitigation Measures Recommended for Construction Phase Impacts of the SWC

Operation Phase Mitigation Measures

9.8.26 Currently the mudflat along the alignment and in the vicinity is occupied by oyster beds. Oyster cultches themselves and the oyster farmer activities would affect bird feeding behaviour. A lower bird density was recorded after the installation of oyster cultches in Ngau Hom Shek (see Appendix 9A). Oyster farming within the alignment and the 50m works area cleared at construction phase would not be allowed to resume. A 8.32 ha restored mudflat (139m x 600m - 0.024 ha occupied by the piers) would be provided in the clearance area in operation phase.

9.8.27 The average diameter of each oyster pole growth with oysters is about 0.2 m. The spacing of each row of oyster beds is about 1 m (parallel to the SWC bridge alignment) and the spacing between two oyster poles is about 0.3 m. The density of oysters in oyster pole is high. Due to irregular surface of the cluster of oysters, the roughness of the oyster poles is expected to be high. The presence of oyster beds may create friction to the tidal flow similar to the bridge piers.

9.8.28 This may lead to the improvement of the tidal flow conditions in the area along the bridge alignment. The clearance of oyster beds along the SWC bridge alignment would be permanent and restoration of oyster beds after the construction works would not be permitted.

9.8.29 Collision: The Additional bird-bridge survey (see Appendix 9A & 9C of this report) and Appendix 9B demonstrate that bridges are not known to function as barriers to bird movements or behaviours nor cause collision of birds. However, based upon the physical and management characteristics of other man-made structures that do function as barriers to bird movements or behaviours, recommendations are listed in Appendix 9B as a precautionary approach to bridge design, construction, and operation (listed below for reader ease). These recommendations are put forward for incorporation into the final bridge design specifications to help ensure that there is no adverse impact of the bridge on local or long-distance bird movements:

· No power lines should be suspended above the bridge deck;
· Cable-stayed portions of the bridge (the navigation channels) should be flood-lit in good weather to increase the visibility of the cables at night to birds;
· Cable-stayed portions of the bridge should be visible to birds in all weather conditions. Consideration should be given to use special red-coloured strobe lighting, to supplement flood lighting in adverse weather conditions including mist, fog and rain. Details should be reviewed in the detailed design stage;
· The bridge deck should be lit to increase visibility of the top of the deck to birds that fly over the bridge at night (standard traffic lighting should accomplish this);
· The undersurface of the bridge should be lit to increase visibility of the piers and undersurface to birds that fly beneath the bridge at night;
· Undersurface lighting should employ flood lights directed at the underside of the bridge deck; and
· Bridge management and maintenance personnel should be required to collect (if possible) and report all cases of bird mortality on the bridge (protocols for collection of carcasses and reporting will be provided).

9.8.30 Marine water quality: This is a water quality mitigation measure intended to minimise degradation of Deep Bay waters from road surface runoff. The road surface and drains are to be cleaned twice a week. Adherence to this schedule should be monitored through periodic on-site inspection and review of logs maintained by cleaning crews. Bridge surface runoff throughout Hong Kong and most of the rest of the world is not managed other than by provision of silt and/or grease traps in the bridge deck. For the SWC bridge potential for pollution of Deep Bay waters will be avoided in part by provision of silt-grease traps. A second level of surface runoff management would be the cleaning of the bridge deck and all silt-grease traps twice a week. The twice-a-week interval was selected because contaminants on road surfaces reach peak concentrations after 10-day periods, after which they are dispersed by wind or gusts caused by passing vehicles. Cleaning twice a week would remove contaminants before they accumulate to levels at which they would be dispersed by wind.

9.8.31 Collected materials would be disposed at a designated landfill site, probably WENT Landfill. In light of global experience with bridges over waterbird and marine resource conservation areas this level of runoff treatment was considered adequate to avoid unacceptable levels of contamination of Deep Bay waters.

9.8.32 The following Table 9.8.3 summarises measures proposed to mitigate operation-phase impacts of the SWC.

Table 9.8.3 Mitigation Measures Recommended for Operation Phase Impacts of the SWC

9.9 Residual Environmental Impacts

9.9.1 If the above mitigation measures are successfully implemented, it was predicted that residual impacts of the SWC bridge could be kept within acceptable limits (Table 9.9.1).

Table 9.9.1 Assessment of Residual Impacts after Implementation of Mitigation Measures

Additional enhancement measures

9.9.2 The preceding discussion has outlined mitigation measures required to minimise negative ecological impacts. The assessment showed that with those mitigation measures, the potential residual negative impacts should be kept to acceptable levels. Additional enhancement measures are, however, proposed to contribute to the long-termed goodness of the Deep Bay ecosystem, and also being precautionary measures. The impacts of displacement and disturbance of BFS and other birds from the peripheral feeding ground in Outer Deep Bay would be of insignificance. Additional enhancement measures, however, could restore their core feeding ground in Inner Deep Bay, and thus act as back-up measures for any unforeseen incidents during the construction phase of SWC.

9.9.3 Additional enhancement measures include a programme to locate and remove exotic mangrove species and weeds (such as Sonneratia spp. & Spartina sp.), so as to restore the mudflat, and a plan to improve the water exchange in Gei Wais.

9.9.4 A search of exotic mangrove species and weed on mudflat (such as Sonneratia spp. and Spartina sp.) will be conducted within inner Deep Bay prior to the commencement of the SWC construction works. Identified individuals or areas of exotic species and weed will be marked on a map of appropriate scale, and removed by contractors at the initial stage of the construction programme. Liaison with AFCD will be conducted for the exact locations and extents of the search covered.

9.9.5 The number of Gei Wais in Hong Kong has been declining since 1960s, and currently there is no Gei Wais operated for commercial purpose in Hong Kong. All remaining Gei Wais are located inside the Mai Po Nature Reserve and managed for conservation purpose, especially wintering birds. Among them, some are still operated in traditional method, and some others have been modified to provide habitats more suitable for bird feeding. By draining these Gei Wais, modified or not, waterbirds can utilise the shallow water inside as feeding ground. Gei Wais in Deep Bay, together with mudflat and fishponds, provide feeding ground for approximately 60,000 wintering birds.

9.9.6 Due to the natural sedimentation, the water channels connecting Gei Wais have become much shallower than before. Some Gei Wais cannot receive regular water exchange as needed. Dredging of the water channels would restore the tidal flushing and water exchange between the mudflat and the Gei Wais.

9.9.7 The sediment deposition rate in the region near Shenzhen River outlet is rather high. Mai Po located near the Shenzhen River outlet is currently being affected by this natural sediment deposition phenomenon. Since mangroves outside the Gei Wais extend in the last few decades, the Gei Wais at Mai Po are now linked to the Deep Bay waters through a number of water channels several hundred metres in length. The increases in channel bed levels as a result of sediment deposition in the water channels obstruct the tidal flows from entering the Gei Wais.

9.9.8 Seawater exchange could bring fish and shrimp into Gei Wais. Without seawater exchange, the food resources inside Gei Wais will be exhausted within days during winter, and their function as feeding ground for the birds is degraded. Previously, the water exchanges of Mai Po Gei Wais could be conducted at 2.2m C.D. in about 15 days per month. Currently the water exchange in the Gei Wais, however, could be conducted only when the sea water level over 2.5m C.D. and the frequency has dropped to about 10 days per month (Young pers. comm.). Previous studies indicated that the food sources of a drained Gei Wai would be exhausted in about three days (WWF 2001). Since the 10 days of water exchange would not be evenly distributed throughout a month, there might be a chance of food resource exhaustion. If the channel beds could be dredged to a lower level, the frequency of seawater exchange could increase, and the incoming flows would be stronger. More food resources would be supplied more frequently for birds. Dredging works in the channels could thus benefit a much larger area inside the connected Gei Wais. The functions of the existing Gei Wais can be restored or enhanced after lowering the water channel bed levels. Dredging at the water channels in Mai Po is to resolve the problem of long-term sediment deposition in the water channels.

9.9.9 Furthermore, the control of water levels within the Gei Wais is crucial for the management of Mai Po Nature Reserve. Retaining a high water level inside Gei Wais in summer could prevent spreading of other vegetation which would occupy soft muddy substrate and interfere feeding activities of certain bird species. Dredging of water channels to restore the suitable depth would help the control of water levels during tidal flushing as water exchange between the mudflat and gei wai could be achieved at a lesser high tide subsequently.

9.9.10 Based on the findings in SWC I&P EIA, sediment deposition rate at Mai Po may slightly increase (+0.5 mm/yr) after the completion of the SWC. Although the impacts due to SWC are insignificant when compared to the natural conditions (sedimentation rate up to about 28 mm/yr in Ramsar Site/Mai Po region), dredging of sediment in the water channels can even up the accumulation of sediments in Mai Po.

9.9.11 Restoration/enhancement of degrading habitats such as Gei Wais in Mai Po would be beneficial to the whole Deep Bay ecosystem. Since the inner Deep Bay is a much more important bird feeding ground than the outer Deep Bay in which SWC is located. It would be more cost-effective if restoration works are conducted in inner Deep Bay as more birds will be benefited.

9.9.12 It is therefore proposed to implement an enhancement measure to dredge the deposited sediment in the water channel, which connects to Mai Po Gei Wai 16/17. Gei Wai 16/17 is the largest Gei Wai inside Mai Po, and has been modified to provide approximately 24.3 ha open area for birds. The modified Gei Wais could provide a larger area of feeding ground than the Gei Wais still retains traditional form. This Gei Wai would be a restoration target of higher cost-effectiveness. Figure 7.31 shows the locations of Gei Wai 16/17 and the inlet water channel connecting to these two Gei Wais.

9.9.13 The proposed dredging would reduce the elevation of the water channel bottom by 1 m. It is expected that after the dredging, the water exchange could be conducted at water level below 2m and on most of the days in a month. The flushing rate and capacity of each water exchange would also be increased. The depth of sediment to be removed would be about 1.0m. According to the current sedimentation rate in the Ramsar Site (about 28mm/yr), the depth of sediment removed would be roughly equal to that accumulated for 30 years. The effect on improving water change capacity could thus last for decades.

9.9.14 An access route would be provided to facilitate the dredging works and mobilization of dredging equipment. Dredging would also be carried out along the access route as shown in Figure 7.31. Though primarily purposed for the transportation of dredging equipment, the dredging of the access route could also provide an alternative pathway of seawater to Gei Wai 16/17. Since the access route would run along the boundary fencing, just outside the seaward bunds of several gei wais to the south of Gei Wai 16/17, it would also result in an improvement of water exchange capacity in these gei wais.

9.9.15 The length of inlet water channel to be dredged is approximately 1.4 km. Elevated land areas on both sides of the inlet water channel are densely populated with mangroves. A portion of the channel of about 600m is on the mudflat and is not bounded by the high population of mangroves. The length of the access route is relatively shorter and is about 800m. The width of dredging along the inlet water channel and the access route is about 4m and the depth of sediment to be removed is about 1.0m. An estimate of the dredged material is approximately 8,800 m3.

9.9.16 The environmental issues associated with the sediment dredging at Mai Po Gei Wais mainly are sediment disposal and water quality impacts, which have been addressed in Section 7 of this report.

9.9.17 A certain number of mangrove plants would need to be removed for the dredging of inlet water channel and access route. Three mangrove species, Kandelia candel, Aegiceras corniculatum, and Avicennia marina, dominate in the Mai Po mangroves seaward to the Gei Wais. Mature Kandelia is exclusive in the most landward part of the mangrove, while the middle part of the mangrove is dominated by Aegiceras and Avicennia, with some young Kandelia. The most seaward part is predominated by young Kandelia. The dredging of access route might affect the mangrove inside an area of 0.32 ha (800m x 4m). The density of Kandelia in that area would be about 2800 No./ha and the diameter of the stem of these mangroves would be about 14.9 cm (Duke & Khan 1999). Potentially 896 mangrove would be lost. It should be noted that the alignment of the access route is indeed an exiting water channel overgrown by mangrove, the 0.32 ha area mentioned above has included the existing water surface of the channel in which there are no mangrove. It was estimated that water surface is occupying about half of the area along the alignment. So the actual number of loss of mangrove would be expected around 448.

9.9.18 The dredging of the inlet water channel would also affect an area of 0.32 ha (800m x 4m). The average density of mangrove would be 9,682 No./ha. The diameters of the stem ranged from 0.8 cm to 14.9 cm. The number of mangrove affected would be about 3,098. Similar with the situation in the access route, the existing water channel might occupy about 1/2 of the 0.32 ha. The actual loss of mangrove would thus be about 1,549. About 49% of the loss in the inlet water channel would be Kandelia, 33% would be Aegiceras and about 18% would be Avicennia (Duke & Khan 1999). There would be totally about 1997 mangrove plants to be affected during the dredging works.

9.9.19 The proposed enhancement measure of dredging the inlet water channel connecting to Mai Po Gei Wai 16/17 would be completed by end of October 2003, i.e. before the wintering period of birds. The preliminary schedule is to complete the dredging work within 4 months with allowance for inclement weather and constraint of tidal conditions. The dredging work would be carried out in advance before the commencement of the main construction contract

9.9.20 Since both the inlet water channel and the access route are shallow and densely populated with mangroves, the dredging vessel should have a low draft, e.g. floating pontoon, in order to access the site. Mitigation measures should be implemented to minimise the water quality impacts associated with the sediment dredging along the inlet water channel and access route. Since the duration for carrying out the enhancement measure is relatively short and the scale of dredging is small, with the implementation of suitable mitigation measures the potential water quality impacts would be within acceptable levels.

9.10 Environmental Monitoring and Audit

9.10.1 The extent of the works areas should be regularly checked during the construction phase. Any trespass by the Contractor outside the limit of the works, including any damage to habitats should be reported to the Engineer.

9.10.2 The progress of the engineering works should be regularly reviewed on site to identify the earliest practical opportunities for implementing ecological mitigation measures.

9.10.3 The Monthly Report shall provide a statement on the general state of ecology in the study area, and confirm that required mitigation measures are being implemented. Effectiveness of the mitigation measures will also be assessed based upon the monitoring data.

9.10.4 The area within the 50m works area will be restored from oyster beds to mudflats to mitigate the temporary and permanent loss of intertidal habitat caused by the pier construction sites and the piers. Oyster beds would be removed before the commencement of construction works. This area should be inspected for the compliance of clearance.

9.10.5 One month before the commencement of construction works, any seagrass beds within the 50m works area boundaries should be marked by visible markings and their total extent will be calculated. An area of exposed mudflat of the equal size will be identified in Pak Nai. Seagrass together with the sediment underneath will be divided into plugs of practical size, removed from Ngau Hom Shek and relocated to the identified area in Pak Nai. The surface of the plugs should be levelled with surrounding sediment at the relocation site. Relocated seagrass plugs should be monitored quarterly for survival and growth during construction phase.

9.10.6 The works area boundaries within the mangal at the shoreline at Ngau Hom Shek should be marked to ensure that work crews and equipment confine all construction activities to the designated works area. Markings should be readily visible, and should be replaced immediately if damaged. Number of mangrove seedlings to be planted and location of planting should be determined during the design and construction stage of the project. Replanting should be conducted within 4 months after the mudflat restoration (clearance of construction materials and wastes) is completed.

9.10.7 Distribution of feeding shorebirds on inter-tidal mudflats near construction sites of the alignment will be studied. Distances of feeding birds on mudflat within 500 m of both sides of the construction site will be recorded. Birds feeding on exposed mudflats and tidelines will be recorded separately. Survey will be carried out when more than 100 m mudflat is exposed, as in the EIA study. A graph showing the distribution pattern of feeding birds around the construction site will be plotted. A control site will be set up on mudflats at Sheung Pak Nai. Distribution pattern of feeding birds on both sides of a strip of mudflat of equal width as the construction sites will be studied in the same way as in the construction site. Distribution patterns of birds at the construction site and control site will be compared using statistical test. Bird abundance and species richness in the construction site and the control site will also be compared with the baseline data of these two locations collected during the field surveys for the EIA study. The data from the control site will provide information on the bird density and composition in the outer Deep Bay area, while the data from the construction site can reflect the potential effect of construction works on birds. Sampling frequency will be once per month throughout the construction phase. Details of the EM&A programme are provided in the EM&A Manual which is required to be made available for public exhibition under the EIAO.

9.10.8 The works area boundaries for the project within the mudflat should be marked to ensure that work crews and equipment confine all construction activities to the designated works area. Markings should be readily visible, and should be replaced immediately if damaged. Construction materials and wastes, or equipment must cleared from the mudflats within two months after the construction period. The profile of the mudflat will be restored to its original conditions.

9.10.9 In operation phase, distribution of feeding shorebirds on inter-tidal mudflats near the bridge will be studied. Distances of feeding birds on mudflat within 500 m of both sides of the bridge will be recorded. Birds feeding on exposed mudflats and tidelines will be recorded separately. Survey will be carried out when more than 100 m mudflat is exposed, as in the EIA study. A graph showing the distribution pattern of feeding birds around the bridge will be plotted. A control site will be set up on mudflats at Sheung Pak Nai. Distribution pattern of feeding birds on both sides of a strip of mudflat of equal width as the bridge will be studied in the same way as in the bridge. Distribution patterns of birds near the bridge and control site will be compared using statistical test. Bird abundance and species richness in the bridge and the control site will also be compared with the baseline data collected at these two locations during the field surveys for the EIA study. The data from the control site will provide information on the bird density and composition in the outer Deep Bay area, while the data from the bridge can reflect the potential effect of bridge structure on birds. In order to study the effect of shade of the bridge on birds, bird abundance and species richness on inter-tidal mudflat right below the bridge will be sampled. Bird abundance and species richness under bridge will be compared with those on mudflat without bridge. Sampling frequency will be once per two months. The monitoring should be carried out for at least 2 years.

9.10.10 Specific types and arrangement of bridge lighting should be designed to minimise the probability of bird collisions during inclement weather (mist, fog, rain). The design and operation of this lighting scheme, together with its performance in terms of bird mortality, should be monitored during the first 2 years of the operation of the bridge. The types of illumination used should be recorded for all weather conditions, and records of any bird fatalities should be documented by date, time, location, weather conditions, type of illumination, number of dead birds by species, and estimated cause of death. Sea surface will be scanned for any floating dead birds. Results of the monitoring study should be used to guide illumination of the bridge in future. Monitoring effort should be concentrated in autumn migration, winter, and spring migration seasons (particularly due to high frequency of misty weather), because these are the times of year when most birds are moving through or residing in Deep Bay. Various combinations of illumination scheme, weather condition, season of year, and time of day should be monitored. The study should be quantitative and designed to enable robust statistical analyses. Monthly surveys are recommended. However, additional surveys will be carried out after days of inclement weather (e.g., misty days, very cold days).

9.10.11 Number of mangrove seedlings planted and location of planting should be checked for compliance with the plan determined during the design and construction stage of the project. Compensatory mangrove planting should be monitored quarterly for survival and growth for 2 years.

9.11 Conclusions

9.11.1 The field survey programme of the present project was planned to be an extension of the field surveys for Crosslinks2 EIA study. A 12-month ecological field survey was conducted for Crosslinks2 between 1998-1999. Fieldwork for the present project began in August 2001 and continued through June 2002 to provide another 11 months of survey data covering seasonal variation and the breeding season and autumn and spring migrations of birds.

9.11.2 Among the four topographic zones in outer Deep Bay area (upland, lowland, coastal/intertidal, and marine), the initial phase of the present field studies identified habitats and species in lowland and coastal zones as key issues for ecology within the assessment area.

9.11.3 Due to the clarification of the demarcation mark between the SWC project and the adjacent Deep Bay Link project, the Assessment Area for the SWC was re-defined as the area below the high water mark. The terrestrial part of the area covered by the field surveys of the SWC project is re-named as Study Area, and the information collected in which is used primarily for supplementary purposes.

9.11.4 The ecological baseline study has covered all items highlighted in the Study Brief of SWC EIA, i.e. intertidal mudflat; mangrove; seagrass bed; inter-tidal and sub-tidal benthic faunal communities; egretries; Horseshoe crabs; avifauna, in particular, Black-faced Spoonbill (Platalea minor); and Chinese White Dolphin (Sousa chinensis).

9.11.5 During the field surveys for the present project, two plant species, including Thespesia populnea and the seagrass Halophila beccarii, one marine invertebrate (horseshoe crab Tachypleus tridentatus), one reptile, 25 species of birds, two species of mammals, including Chinese White Dolphin, were recorded within the assessment area and are of conservation concern.

9.11.6 Among those species of conservation concern recorded, however, only the seagrass Halophila beccarii, horseshoe crab Tachypleus tridentatus, and 10 waterbird species including Black-faced Spoonbill are considered that their presence in the assessment area is relevant to the SWC project.

9.11.7 In terms of avoidance, based upon information from literature review and field surveys, it was found in the assessment that the current location of the Shenzhen Western Corridor would cause the least impact to Deep Bay. The current location is 6km from Mai Po Marsh Nature Reserve, 7km from the mouth of Deep Bay, and 3.5km from Ha Pak Nai. The potential impacts on recognised sites of conservation importance would be higher if the corridor location was further northward (potential impacts on Mai Po), or further southward (potential impacts on Chinese White Dolphin). The current location of SWC is thus considered the most ecologically acceptable if a non land-based western corridor is needed.

9.11.8 The most important form of mitigation, avoidance, has already been pursued through consideration of three alternative sites for the bridge landing. The Ngau Hom Shek was determined to be the least damaging ecologically and the most preferred all round

9.11.9 Tunnel option was found to be less ecologically acceptable due to the need of large scale dredging during construction and the higher reduction o flushing rate during operation.

9.11.10 Several design features of the bridge could effectively minimise ecological impacts, including increasing pier spacing, adopting submerged pile caps, locating cable-stayed structure outside intertidal zone, bridge deck height, and no power line suspended on the bridge.

9.11.11 During construction, the cumulative temporary direct habitat loss will be about 2.7 ha in subtidal zone, and 0.75 ha in intertidal zone, due to construction and use of the temporary bridge, plus 0.25 ha removal of mangrove trees. Only less than 0.001 ha of seagrass might be potentially influenced. Temporary direct BFS feeding ground loss would be 0.139ha. In operation phase, the resulted permanent habitat loss will be less than 0.2 ha in subtidal zone and 0.024 ha in intertidal zone. Permanent BFS feeding ground direct loss would be 0.039ha.

9.11.12 The indirect impacts on habitats due to disturbance were investigated through additional filed surveys in other bridge structures in HK and Macau, and analyses of data in other projects. The finding indicates that most birds are disturbance-tolerant. Even Black-faced spoonbill (BFS), which is previously considered much sensitive to disturbance, was observed feeding close to disturbance sources. Precautionary approach is however adopted. In the worst case scenario, in which disturbance occurs in the exposed intertidal zone within the 50m works area, which is primarily purposed for vessel access in subtidal zone or, during high tide, in intertidal zone, the affected BFS feeding ground is estimated to be 0.24 ha in area, which has included the 0.139ha of direct temporary loss. Previous studies indicated that mudflat is only one of the feeding ground types of BFS (the other two are drained fishponds and drained gei wai), and the outer deep Bay (including the mudflat near the SWC alignment) is not the core feeding area of BFS. This 0.24 ha represents a small fraction (1.6%) of the intertidal feeding habitat for BFS along the south shore of outer Deep Bay (some 15 km in length x 10 m in width = 15 ha) which is less important to the BFS than the inner Deep Bay. The temporary loss is predicted to be an undetectable impact. For the operation phase, though there is no evidence to prove that BFS would avoid the mudflat in the vicinity of a bridge, based upon a precautionary approach, an additional 30m on both side of the SWC deck width was included to address this potential impact. The total permanent loss of BFS potential feeding ground, including both direct and indirect, would then be 0.039ha + 0.06ha = 0.099ha. Since a 8.34 ha of mudflat would be restored in operation phase, a 0.139 ha tideline (= (39m + 50m + 50m) x 10m) will be provided. After reduction of the 0.099 ha potential loss, there still would be 0.04ha tideline feeding ground for BFS restored.

9.11.13 There would be no cumulative impacts in terms of disturbance. The only cumulative impact identified was an additional ~150ha seabed loss. The loss was insignificant to Deep Bay. Even including the seabed loss from the SWC project, the cumulative seabed loss would be only about 1.3% of Deep Bay. The cumulative impacts from the present project would be acceptable.

9.11.14 During construction, dredging, intertidal habitat loss, damage due to construction and use of the temporary bridge may result in minor impacts on mudflats, mangroves, seagrass, and pelagic species.

9.11.15 All other construction impacts would be insignificant in severity.

9.11.16 Implementation of the recommended mitigation measures would result in no unacceptable residual impacts.

9.11.17 All long-term impacts from operation of the bridge were predicted to be insignificant or minor and could be mitigated with no unacceptable residual impact.

9.11.18 Additional enhancement measures are, however, proposed on a precautionary approach to provide alternative and superior feeding sites for birds to contribute to the long-termed goodness of the Deep Bay ecosystem, including a programme to locate and removal of exotic mangrove species and weeds (such as Sonneratia spp. & Spartina sp.) and a plan to restore the function of Gei Wais in Mai Po as bird feeding ground.

9.11.19 By ecovering the level of the bottoms of water channels connecting Gei Wais and Deep Bay, the function of 24.3 ha Gei Wai in Mai Po, which is the core feeding ground of BFS, will be restored. This area would be over 20 times the temporary peripheral feeding ground loss for all birds in the SWC construction phase. This plan will be conducted before the commencement of SWC construction works and the function of restoration achieved could last for over a decade.

Shenzhen Western Corridor EIA -Ecological Impact and Mitigation Plan

9.12 References

Agriculture & Fisheries Department (AFD). 1995. Categorization of Agricultural Land. (Revised 1995.) Agriculture & Fisheries Department, Hong Kong Government.

Anon. 1995a. Register of Sites of Special Scientific Interest (SSSIs). Loose-leaf document maintained by Planning Department, Hong Kong Government

Anon. 1995b. Focus on Fish Ponds: V and VI. Porcupine! 13 (Aug. 1995). (Newsletter of the Dept. of Ecology and Biodiversity, Hong Kong Univ.)

Arup. 2002. Final EIA Report. Agreement No. CE109/98, Deep Bay Link Investigation and Preliminary Design. Highways Department, Government of Hong Kong Special Administrative Region. Ove Arup & Partners Hong Kong Limited, 2002.

Barretto, G. and L. Chau. 1996. New orchid in bogland. Porcupine! 15 (Dec. 1996):8. (Newsletter of the Dept. of Ecology and Biodiversity, Hong Kong Univ.)

Bascombe, M. J., G. Johnston and F. S. Bascombe. 1999. The butterflies of Hong Kong. Academic Press, London. 422pp.

Binnie Consultants Ltd. 1997. Final Assessment Report for EIA of Tin Shui Wai Development. Volume 1. Prepared for Territory Development Department.

BirdLife International. 2000. Threatened Birds of the World. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International.

Carey, G. J. 1998. Waterfowl Monitoring at the Mai Po Inner Deep Bay Ramsar Site: Monthly Waterfowl Counts November 1997-October 1998. Hong Kong Bird Watching Society, Hong Kong.

Carey, G. J. 1999a. Egretry counts in Hong Kong, with particular reference to the Mai Po and Inner Deep Bay Ramsar Site - Summer 1998 Report. The Hong Kong Bird Watching Society.

Carey, G. J. 1999b. Waterfowl Monitoring at the Mai Po Inner Deep Bay Ramsar Site: Monthly Waterfowl Counts October 1998-September 1999. Hong Kong Bird Watching Society, Hong Kong.

Carey, G. J. 2000a. Review of mid-winter waterfowl count data collected by the Hong Kong Bird Watching Society. Report to Agriculture, Fisheries & Conservation Dept., Government of Hong Kong Special Administrative Region.

Carey, G. J. 2000b. Waterfowl Monitoring at the Mai Po Inner Deep Bay Ramsar Site: Monthly Waterfowl Counts October 1999-March 2000. Hong Kong Bird Watching Society, Hong Kong.

Carey, G. J. 2001. Waterfowl Monitoring at the Mai Po Inner Deep Bay Ramsar Site: Monthly Waterfowl Counts April 2000-March 2001. Hong Kong Bird Watching Society, Hong Kong.

Carey, G. J. and L. Young. 1999. The importance to waterfowl of the Mai Po Marshes and Inner Deep Bay Ramsar Site. Hong Kong Bird Report 1997: 141-149.

Carey, G. J., D. A. Diskin, P. J. Leader, H. F. Cheung, R. W. Lewthwaite, M. L. Chalmers and P. R.

Kennerley. 1997. Systematic list. pp. 13-87 in Carey, G. J. (ed.) Hong Kong Bird Report 1996. Hong Kong Bird Watching Society, Hong Kong.

Carey, G.J., Chalmers, M.L., Diskin, D.A., Kennerley, P.R., Leader, P.J., Leven, M.R., Lewthwaite, R.W., Melville, D.S., Turnbull, M. and Young, L. 2001. The Avifauna of Hong Kong. Hong Kong Bird Watching Society, Hong Kong.

Chalmers, M. L. 1998. Black-faced Spoonbill nest-building at Mai Po. Hong Kong Bird Report 1996: 170.

Chen, D. S. and R. R. Wu. 1997. Report on observations of the Indo-Pacific Hump-backed Dolphin in the Pearl River Estuary. Shuichan Keji (Fisheries Science and Technology) 72:1-2. (In Chinese.)

Chen, G. Z., Y. J. Wang. and Q. L. Huang. 1997. A study on the biodiversity and protection of mangroves and birds in Futian National Reserve, Shenzhen. Chinese Biodiversity 5(2): 104-111. (In Chinese.)

Chen, L. 1990. A study of fauna characteristics of fishes and shrimp in the Pearl River Estuary. South China Sea Fisheries Research 2:21-31. (In Chinese.)

Chen, Z. R. et al. 1995. Ecological characteristics of ichthyoplankton in the Pearl River Estuary. pp. 46-57 in: Zhujiang and Coastal Environmental Research. Guangdong Provincial Higher Education Press, Guangzhou. (In Chinese.)

China Green Environment and Development Center (CGEDC). 1996a. Shenzhen-Hong Kong Western Corridor (Shenzhen Bay Bridge) Environmental Impact Assessment -Outline. Prepared by National Environmental Protection Agency, China Green Environment and Development Center. Dated Sept. 1996. (In Chinese.)

China Green Environment and Development Center (CGEDC). 1996b. Shenzhen-Hong Kong Western Corridor (Shenzhen Bay Bridge): Studies on Shenzhen Bay Water Quality and Ecological Impact. Prepared by National Environmental Protection Agency, China Green Environment and Development Center. Dated Dec. 1996. (In Chinese.)

Chiu, H.M.C. and B. Morton 1999. The Biology, Distribution, and Status of Horseshoe Crabs Tachypleus tridentatus and Carcinoscorpius rotundicauda (Arthropoda: Chelicerata) in Hong Kong: Recommendations for Conservation and Management. Final Report to China Light and Power Company Limited. The Swire Institute of Marine Science, The University of Hong Kong, Hong Kong.

Chu, W. H. 1995. Fish ponds in the ecology of the inner Deep Bay wetlands of Hong Kong. Asian J. Env. Manage. 3(1):13-36.

Chu, W. H. 1998. Conservation of Terrestrial Biodiversity in Hong Kong. Unpubl. M.Phil. thesis. Dept. of Ecology and Biodiversity, University of Hong Kong.

Chu, W. H. and F. W. Xing. 1997. A checklist of vascular plants found in fung shui woods in Hong Kong. Memoirs of the Hong Kong Natural History Society 21:151-172.

CMD International. 2000. Feasibility Study of Waste-to-Energy Incineration Facilities: Site Assessment Report (Ha Pak Nai) Final Report. Environmental Protection Department, Hong Kong.

Corlett, R. T., F. W. Xing, S. C. Ng, L. K. C. Chau and L. M. Y. Wong. 2000. Hong Kong vascular plants: Distribution and status. Mem. Hong Kong Nat. Hist. Soc. 23.

Corlett, R. T. 2001. Is the Javan Mongoose native and does it matter? Porcupine! 24:19.

Dahmer, T. D., M. L. Yau, M. Felley, and O. Chope. (in review) Mangal restoration on Kau Sai Chau, Hong Kong. Submitted to Restoration Ecology, Dec. 2001.

Dahmer, T. D. H. K. Kwok, and M. L. Felley. 2001. New reptile and amphibian records for Kau Sai Chau, Sai Kung. Porcupine! 23:13-15.

Dahmer, T. D. and M. L. Felley (in prep.) Global Population Estimates for Black-faced Spoonbill Platalea minor, 1988-2001

Dahmer, T. D. and M. L. Felley. 1998. Black-faced Spoonbill (Platalea minor) Census, January 1998.

Diskin, D. 1997. Birding Hong Kong - A Site Guide.

Dudgeon, D. and E. W. C. Chan. 1996. Ecological Study of Freshwater Wetland Habitats in Hong Kong. Report prepared for the Agriculture and Fisheries Department, Hong Kong Government. Dated Nov. 1996.

Duke, N.C. and M.A. Khan. 1999. Structure and Composition of the Seaward Mangrove Forest at the Mai Po Marshes Nature Reserve, Hong Kong. pp. 83- 104. In S.Y. Lee (ed.), The Mangrove Ecosystem of Deep Bay and the Mai Po Marshes, Hong Kong. Proceeding of the international Workshop on the Mangrove Ecosystem of Deep Bay and the Mai Po Marshes, Hong Kong, 3-20 September 1993. Hong Kong: Hong Kong University Press, 1999.

Environmental Protection Department (EPD). 1997. Marine Water Quality in Hong Kong in 1996. Results for 1996 from the Marine Monitoring Programme of the Environmental Protection Department. Printing Department, Hong Kong.

Environmental Protection Department (EPD). 2001a. Marine Water Quality in Hong Kong in 2000. Results for 2000 from the Marine Monitoring Programme of the Environmental Protection Department. Printing Department, Hong Kong.

Environmental Protection Department (EPD). 2001b. River Water Quality in Hong Kong in 2000. Results for 2000 from the River Water Quality Monitoring Programme of the Environmental Protection Department. Printing Department, Hong Kong.

Environmental Resources Ltd. (ERL). 1988a. Deep Bay Integrated Environmental Management. Key Issues.

Environmental Resources Ltd. (ERL). 1988b. Environment Review: Deep Bay Management. Executive Summary.

ERL (Asia) Ltd. 1992. EIA of the Proposed 6000MW Thermal Power Station at Black Point: Initial Assessment Report. Volume 1. The Surrounding Environment. Report prepared for China Light and Power Company Ltd. Dated Nov. 1992.

ERL (Asia) Ltd. 1993. EIA Island Transfer Station Dredging of WENT Fairway. Environmental Protection Department. June 1993.

ERM (Hong Kong). 1993. EIA of the Proposed 6000MW Large Thermal Power Station at Black Point. Key Issue Assessment. Sept. 1993.

ERM. 1995. EIA for Proposed Aviation Fuel Receiving Facility at Sha Chau. Final Report. Vol. 2, Annexes. Provisional Airport Authority. January 1995.

ERM-Hong Kong, Ltd. 1997. EIA Study for Disposal of Contaminated Mud in the East Sha Chau Marine Borrow Pit. Report prepared for CED.

ERM-Hong Kong, Ltd. 1998. Final Assessment Report: West Kowloon to Tuen Mun Centre. Kowloon-Canton Railway Corporation West Rail Environmental Impact Assessment. Contract No. TS-900. Report prepared for KCRC, dated 11 Feb. 1998.

Fellowes J.R., et al. 2002. Wild animals to watch: Terrestrial and freshwater fauna of conservation concern in Hong Kong. Memoirs of the Hong Kong Natural History Society No. 25. Pp. 123-160.

Fong, T. C-W. 1998. Distribution of Hong Kong seagrasses. Porcupine! 18 (Dec. 1998): 10-12. (Newsletter of the Dept. of Ecology and Biodiversity, Hong Kong Univ.)

Fong, T. C-W. 1999. Tai Ho Wan: breeding and nursery ground of horseshoe crabs in Hong Kong, and some notes on the ecology of Starling Inlet. Porcupine! 20 (Nov. 1999): 12-14. (Newsletter of the Dept. of Ecology and Biodiversity, Hong Kong Univ.)

Fu, Y. Y, J. Q. Yin, Q. C. Chen, L M. Huang and C. K. Wong. 1995. Distribution and seasonality of marine zooplankton in the Pearl River Estuary. pp. 25-33 in: Environmental Research in Pearl River and Coastal Areas. Guangdong Higher Education Press, Guangzhou.

Greiner Maunsell. 1992. Castle Peak Borrow Area EIA. Prepared for Provisional Airport Authority - Hong Kong. August 1992.

Hammond, N. and B. Pearson 1993. Hamlyn bird behaviour guides - Birds of Prey. Hamlyn, London.
He, B. Q. and H. Q. Li. 1991. The resources character of fishes and shrimps in the Pearl River Estuary. South China Sea Fisheries Research 3:3-21. (In Chinese.)

He, B. Q. and Q. Z. Lin. 1988. Fisheries and fisheries resources in the Pearl River Estuary and inshore waters. Shuichan Keji (Fisheries Science and Technology) 2 of 1988:1-8. (In Chinese.)

HKBWS. 1997-2001. Waterfowl monitoring at the Mai Po Inner Deep Bay Ramsar Site. Hong Kong Bird Watching Society report to Agriculture, Fisheries & Conservation Dept., Government of Hong Kong Special Administrative Region.

HKBWS. 1998-2001. Egretry counts in Hong Kong, with particular reference to the Mai Po Inner Deep Bay Ramsar Site. Hong Kong Bird Watching Society report to Agriculture, Fisheries & Conservation Dept., Government of Hong Kong Special Administrative Region.

Hodgkiss, I. J. and B. Morton 1978. Halophila beccarii Ascherson (Hydrocharitaceae) - a new record for Hong Kong, with notes on other Halophila species. Memoirs of the Hong Kong Natural History Society 13:28-32.

Hong Kong - Guangdong Environmental Protection Liaison Group (HKGEPLG). 1992. Technical Report on the Environmental Protection of Deep Bay and its Catchments. Report of the HKGEPLG Technical Sub-Group. Dated Dec. 1992.

Hua, H. L and J. W. Yin. 1993. Protected Animals in China. Shanghai Scientific and Technological Education Publishing House. (In Chinese.)

Huang, D. M. 1986. Report of a study on Collichthys lucidus and Coilia grayii resources. Shuichan Keji (Fisheries Science and Technology) 2 of 1986: 15-16. (In Chinese.)

Huang, Q. 1997. Hong Kong's horseshoe crabs. Porcupine! 16 (July 1997):17-18. (Newsletter of the Dept. of Ecology and Biodiversity, Hong Kong Univ.)

Irving, R. and B. Morton. 1988. A Geography of the Mai Po Marshes. Hong Kong University Press, Hong Kong.

Jefferson, T. A. 2000. Population biology of the Indo-Pacific Hump-backed Dolphin in Hong Kong waters. Wildlife Monographs 144:1-65.

Jefferson, T. A. 1998. Population Biology of the Indo-Pacific Hump-backed Dolphin (Sousa chinensis Osbeck, 1765) in Hong Kong Waters: Final Report. Report submitted to Agriculture and Fisheries Dept., Hong Kong Govt. Dated 15 April 1998.

Jefferson, T. A. and S. Leatherwood. 1998. Distribution and abundance of Indo-Pacific hump-backed dolphins (Sousa chinensis Osbeck, 1765) in Hong Kong waters. Asian Marine Biology 14: 93-110.

Karsen, S. J., W. N. Lau and A. Bogadek. 1986. Hong Kong Amphibians and Reptiles. Urban Council, Hong Kong.

Kerlinger, P. 1998. Showdown at Delaware Bay. Natural History 107(4):56-58.

Kwok, H. K., Wong, L. C. and Carey, G. J. 2001. Egretry counts in Hong Kong, with particular reference to the Mai Po and Inner Deep Bay Ramsar Site - Summer 2000 Report. The Hong Kong Bird Watching Society.

Kwok, K. 1993. Effect of water level fluctuation of gei wais on distribution of waders in the Mai Po Marshes. Dissertation of Department of Applied Science, City University of Hong Kong.

Lam, W. W. 1987. The Tap Shek Kok Power Plant: A Marine Environmental Impact Assessment. PhD Thesis (2 vols.). University of Hong Kong.

Landsdown, R. V., Mundkur, T. and Young, L. 2000. Herons in East and South-east Asia. pp 73-98, in (J. A. Kushlan and H. Hafner). Heron Conservation. Academic Press, Great Britain.

Lau, M. W. N. 1995. Notes on the herpetofauna on Neilingding Island in the Pearl River Estuary, China. Memoirs of the Hong Kong Natural History Society 20:209-213.

Lau, M., G. Reels and J. Fellowes (eds.). 1996. The Biodiversity Survey: highlights of the first year. Porcupine! No. 15 (Dec. 1996):33-35. (Newsletter of the Dept. of Ecology and Biodiversity, Hong Kong Univ.)

Lau, M.W.N. and D. Dudgeon. 1999. Composition and distribution of Hong Kong Amphibian fauna. Memoirs of the Hong Kong Natural History Society 22: 1-80.

Leader, P. J. 1998. Preliminary observation on the ecology of Black-faced Spoonbills in Hong Kong. Hong Kong Bird Report 1996: 145-157.

Lee, S. Y. 1993. Invertebrate species new to science recorded from the Mai Po Marshes, Hong Kong. pp. 199-210 in: B. Morton (ed.) Marine Biology of the South China Sea. Vol. 1. Proceedings of the First International Conference on the Marine Biology of Hong Kong and the South China Sea, Hong Kong, 28 October - 3 November 1990. Hong Kong University Press, Hong Kong.

Lee, S. Y. (ed.) 1999. The Mangrove Ecosystem of Deep Bay and the Mai Po Marshes, Hong Kong. Proceedings of the International Workshop on the Mangrove Ecosystem of Deep Bay and the Mai Po Marshes, Hong Kong, 3-20 September 1993. Hong Kong University Press, 189pp.

Lee, S. Y. and V. Leung. 1999. The brachyuran fauna of the Mai Po Marshes Nature Reserve and Deep Bay, Hong Kong. Pages 57-82 in Lee, S. Y. (ed.) The Mangrove Ecosystem of Deep Bay and the Mai Po Marshes, Hong Kong. Proceedings of the International Workshop on the Mangrove Ecosystem of Deep Bay and the Mai Po Marshes, Hong Kong, 3-20 September 1993. Hong Kong University Press, 189pp.

Leung, S. F. 1999. The species composition of penaeid prawns in the north-western waters of Hong Kong. Pages 3-11 in Lee, S. Y. (ed.) The Mangrove Ecosystem of Deep Bay and the Mai Po Marshes, Hong Kong. Proceedings of the International Workshop on the Mangrove Ecosystem of Deep Bay and the Mai Po Marshes, Hong Kong, 3-20 September 1993. Hong Kong University Press, 189pp.

Leung, C., Shortridge, K. F., Morton, B. and Wong, P. S. 1975. The incidence of faecal bacteria in the tissues of the tissues of the commercial oyster Crassostrea gigas Thunberg correlated with the hydrology of Deep Bay, Hong Kong. pp. 114-27: in: B. Morton (ed.): Proceedings of the Pacific Science Association Special Symposium on Marine Sciences, Hong Kong 1973. Government Printer, Hong Kong.

Li, W. and X. Zhao. 1989. China's Nature Reserves. Foreign Languages Press, Beijing.

Liang, G. Y. and L. J. Zhou. 1987. Preliminary survey of horseshoe crab resources in Beibu Bay, Chia. Haiyang Yaowu (Marine Pharmaceuticals) (4):31-33.

Magurran, A. E. 1988. Ecological Diversity and Its Measurement. Croom Helm Ltd., London.

Maunsell Consultants Asia Ltd. 1997. Outlying Islands Sewerage - Stage I Phase I. Environmental Impact Assessment Report - Final Assessment Report. Prepared for Drainage Services Department. Dated Sept. 1997.

Melville, D. 1980. Birds at Kai Tak Airport, Hong Kong. Agricultural and Fisheries Department, Hong Kong.

Melville, D. S., L. Young and P. J. Leader. 1994. The Importance of Fish Ponds Around Deep Bay to Wildlife Especially Waterbirds: Together with a Review of Potential Impacts of Wetland Loss and Mitigation Measures. World Wide Fund for Nature Hong Kong. July 1994.

Melville, D. S., S. McChesney, C. Anderson and P. J. Leader. 1997. Predicted impacts of the Shenzhen River Regulation Project on waterfowl in Deep Bay, Hong Kong. In Goss-Custard, J. D., Rufino, R. and Luis, A. Effect of habitat loss and change on waterbirds. The Stationery Office, London.

Melville, D. S., S. Y. Lee and W. W. Cheng. 1989. Some aspects of the management of the Mai Po Marshes, Deep Bay, Hong Kong. pp. 94-104 in: D. Parish and R. C. Prentice (eds.), Wetlands and Waterfowl Conservation in Asia. AWB/IWRB, Kuala Lumpur.

Morton, B. and J. E. Morton. 1983. The Sea Shore Ecology of Hong Kong. Hong Kong University Press, Hong Kong.

Mouchel Asia Ltd. 1997. Feasibility Study for Additional Cross-Border Links Stage 2: Investigations on Environment, Ecology, Land Use Planning, Land Acquisition, Economic/Financial Viability and Preliminary Project Feasibility/Preliminary Design. Water Quality Impact Assessment Review Paper. Prepared for Planning Department, HK SAR Govt. Report dated Dec. 1997.

Mouchel Asia Ltd. 1998. Water Quality Impact Assessment. Working Paper 2. (Deep Bay Crossing and Lingdingyang Bridge) Feasibility Study for the Additional Cross Border Links: Stage 2 Investigations on Environment, Ecology, Land Use Planning, Land Acquisition, Economic/Financial Viability and Preliminary Project Feasibility/Preliminary Design. Prepared for Planning Department, HKSAR Govt. Dated Dec. 1998.

Mouchel. 1999. Final Ecological Impact Assessment, Working Paper WP3. Feasibility Study for Additional Cross-Border Links Stage 2: Investigations on Environment, Ecology, Land Use Planning, Land Acquisition, Economic/Financial Viability and Preliminary Project Feasibility/Preliminary Design. W. Prepared for Planning Department, HK SAR Govt. Report dated Dec. 1999.

Ni, I. H. 1997. Seasonal variability of fishery resources in the east of Sha Chau. pp. 69-83 in: Proceedings of a Colloquium for Development of a Management Strategy for Chinese White Dolphins, 1-3 July 1996. Agriculture and Fisheries Department, Govt. of the HK SAR.

Pan, J. H. et al. 1991. Freshwater Fish Fauna of Guangdong. Guangdong Science Press, Guangzhou. (In Chinese.)

Parsons, E. C. M. 1997. Hong Kong's Cetaceans: The Biology, Ecology and Behaviour of Sousa chinensis and Neophocaena phocaenoides. Unpubl. PhD thesis, Dept. of Ecology and Biodiversity, University of Hong Kong. 257pp.

Pearson, T. H. and R. Rosenberg. 1978. Macrobenthic succession in relation to organic enrichment and pollution of the marine environment. Oceanography and Marine Biology Annual Review 16:229-311.

Peking University. undated. Environmental Impact Assessment Study on Shenzhen River Regulation Project (Final EIA Study Report (III) - Ecology.)

Peng, Y. H., J. H. Chen, Q. Y. Cai and L. D. Chen. 1991. Study of water temperature and salinity in the Pearl River Estuary. Nanhai Yanjiu yu Kaifa (South China Sea Research and Development) 4:32-37. (In Chinese.)

Pielou, E. C. 1966. Shannon's formula as a measure of species diversity : its use and misuse. American Naturalist 100:463-465.

Planning Department. 1993. Territorial Development Strategy Review. Environmental Baseline Conditions.

Planning Department, Hong Kong Government, July 1993.

Planning, Environment and Lands Branch (PELB), Government Secretariat. 1996. Heading Toward Sustainability: The Third Review of Progress on the 1989 White Paper Pollution in Hong Kong -- A Time to Act. March 1996. Government Printer, Hong Kong.

Podolsky, R., D. G. Ainley, G. Spencer, L. Deforest and N. Nur. 1998. Mortality of Newell's Shearwaters caused by collisions with urban structures on Kauai. Colonial Waterbirds 21(1):20-34.

Qiu, J. W. 1999. Composition, structure and distribution of polychaete assemblages in Deep Bay, Hong Kong. Pages 13-22 in Lee, S. Y. (ed.) The Mangrove Ecosystem of Deep Bay and the Mai Po Marshes, Hong Kong. Proceedings of the International Workshop on the Mangrove Ecosystem of Deep Bay and the Mai Po Marshes, Hong Kong, 3-20 September 1993. Hong Kong University Press, 189pp.

Reels, G. T. 1994. Management strategies for the reed Phragmites australis (CAV.) Steud. at Mai Po Marshes Nature Reserve, HK with observations on the associated insect fauna. M.Phil thesis. The University of Hong Kong.

Reels, G. T. and G. Walthew. 1998. Status of Hong Kong butterflies - an update. Porcupine! 17 (August 1998): 11. (Newsletter of the Dept. of Ecology and Biodiversity, Hong Kong Univ.)

Richards, J. and R. S. S. Wu. 1985. Inshore fish community structure in a subtropical estuary. Asian Marine Biology (2):57-68.

Scott Wilson Kirkpatrick (SWK). 1993. Tuen Mun Port Development Study. Final Report. Volume 1. Territorial Development Department. December 1993.

Scott Wilson Kirkpatrick (SWK). 1997. Foothills Bypass, Tuen Mun Road/Wong Chu Road Interchange and Other Road Junction Improvement Links - EIA. (Agreement No. CE 44/95) Report prepared for TDD.
Sekiguchi, K. (ed.) 1988. Biology of Horseshoe Crabs. Science House Company Ltd., Tokyo.
Shannon, C. E. and Weaver, W. 1963. The Mathematical Theory of Communication. University of Illinois Press. Urbana, 117pp.

Shea, S. S., L. Smith and P. Sanders. 1995. Ecological impact assessment and ecological monitoring of a strategic landfill: a case study in Hong Kong. pp. 30-39 in: Proceedings of The First Symposium of Chinese Zoologists in Southeast Asia, Guangzhou, 14-17 December 1994. Supplement to The Journal of Sun Yatsen University 1995 (3).

Smith-Evans, M. and A. Dawes. 1996. Early experiences in monitoring the effects of Hong Kong's new generation of sewage outfalls on the marine environment. Marine Pollution Bulletin 3(7-12):317-327.
South China Sea Fisheries Regulation Agency (SCSFRA). 1985. Map of Fisheries Resource Protection Zones in the South China Sea. Dated August 1985. (In Chinese.)

Swire Institute of Marine Science (SWIMS). 1994. Seagrass Rehabilitation at Tung Chung (PADS/1): Final Report. Dated Dec. 1994.

Tam, N. F. Y. and Y. S. Wong. 1997. Ecological Studies on Mangroves in Hong Kong. Report submitted to Agriculture and Fisheries Department, Hong Kong Special Administration Region Government. November 1997. Volume 1.

Thrower, S. L. 1988. Hong Kong Trees. Omnibus Volume. Urban Council, Hong Kong.
Town Planning Board (TPB). 1994. Town Planning Board Guidelines for Application for Developments Within Deep Bay Buffer Zones Under Section 16 of the Town Planning Ordinance. TPB PG-No. 12A (Revised November 1994).

Viney, C., K. Phillipps and C. Y. Lam. 1994. Birds of Hong Kong and South China. Government Printer, Hong Kong.

Walthew, G. 1997. The status and flight periods of Hong Kong butterflies. Porcupine! 16 (July 1997): 34-37. (Newsletter of the Dept. of Ecology and Biodiversity, Hong Kong Univ.)

Wang, C. 1993. Ecological characteristics of the fish fauna of the South China Sea. pp. 77-118 in: B. Morton (ed.) The Marine Biology of the South China Sea Vol. 1. Proceedings of the First International Conference on the Marine Biology of Hong Kong and the South China Sea, Hong Kong, 28 October - 3 November 1990. Hong Kong University Press, Hong Kong.

Wang, P. L. 1998. The Chinese White Dolphin and the Dugong. China Nature 1998(2):8-9. (In Chinese.)
Wang, S. 1998. China Red Data Book of Endangered Animals: Aves. Science Press, Beijing.

Weatherhead, M. A. Undated. The Distribution and Ecology of Nepenthes mirabilis in Hong Kong. Final Report for the Months January to June 1996. Unpublished report submitted to Agriculture and Fisheries Department, Hong Kong Government.

Wilson, K. D. P. 1995. Hong Kong Dragonflies. Urban Council, Hong Kong.

Wilson, K. D. P. 1997. An annotated checklist of the Hong Kong dragonflies with recommendations for their conservation. Memoirs of the Hong Kong Natural History Society 21: 1-68.

Wong, C. 1998. A new site for the seagrass Halophila beccarii in Hong Kong, and some notes on the ecology of Starling Inlet. Porcupine! 17 (Aug. 1998): 22. (Newsletter of the Dept. of Ecology and Biodiversity, Hong Kong Univ.)

Wong, F. K. O. 1991. Habitat utilisation by Little Egrets breeding at Mai Po egretry. Hong Kong Bird Report 1990: 185-190.

Wong, L. C. and Kwok, H. K. 2002. Egretry counts in Hong Kong, with particular reference to the Mai Po and Inner Deep Bay Ramsar Site - Summer 2001 Report. The Hong Kong Bird Watching Society.

Wong, L. C. 2002. Pilot study: Feeding habitat use and foraging flights of ardeid nesting in the Mai Po Inner Deep Bay Ramsar Site, Hong Kong - Waterbird Monitoring at the Mai Po and Inner Deep Bay Ramsar Site. The Hong Kong Bird Watching Society, Hong Kong.

Wong, L. C., Kwok, H. K. and Carey, G. 2000. Egretry counts in Hong Kong, with particular reference to the Mai Po and Inner Deep Bay Ramsar Site - Summer 1999 Report. The Hong Kong Bird Watching Society.

World Wide Fund for Nature (Hong Kong) (WWF). 2001a. Preparation of a Conservation Plan for the Black-faced Spoonbill (Platalea minor) in Hong Kong, Tech. Report 1-Reviews and Strategies. Project No. WFC/1/99, Agriculture, Fisheries & Conservation Department, Government of Hong Kong Special Administrative Region, Cheung Sha Wan, Kowloon, Hong Kong, 115pp.

World Wide Fund for Nature (Hong Kong) (WWF). 2001b. Preparation of a Conservation Plan for the Black-faced Spoonbill (Platalea minor) in Hong Kong, Tech. Report 2-Additional Works. Project No. WFC/1/99, Agriculture, Fisheries & Conservation Department, Government of Hong Kong Special Administrative Region, Cheung Sha Wan, Kowloon, Hong Kong, 55pp.

World Wide Fund for Nature (Hong Kong) (WWF). 2001c. Preparation of a Conservation Plan for the Black-faced Spoonbill (Platalea minor) in Hong Kong, Conservation Plan. Project No. WFC/1/99, Agriculture, Fisheries & Conservation Department, Government of Hong Kong Special Administrative Region, Cheung Sha Wan, Kowloon, Hong Kong, 57pp.

World Wide Fund for Nature (Hong Kong) (WWF). undated a. Diving and Estuarine Ducks. Mai Po Nature Reserve.

World Wide Fund for Nature (Hong Kong) (WWF). undated b. Dabbling Ducks. Mai Po Nature Reserve.

World Wide Fund for Nature (Hong Kong) (WWF). undated c. Butterflies. Mai Po Nature Reserve.

World Wide Fund for Nature (Hong Kong) (WWF). undated d. Reptiles and Amphibians. Mai Po Nature Reserve.

World Wide Fund for Nature (Hong Kong) (WWF). undated e. Gulls & Terns. Mai Po Nature Reserve.

World Wide Fund for Nature (Hong Kong) (WWF). undated f. Fact Sheet: Ramsar Convention and Mai Po Nature Reserve.

Wu, R. R. and L. X. Lin. 1992. Trends in net fisheries resources in the Pearl River Estuary. Shuichan Keji (Fisheries Science and Technology) 3 of 1992:1-4. (In Chinese.)

WWF-HK. 1999. Preparation of a conservation plan for the Black-faced Spoonbill (Platalea minor) in Hong Kong. Report to Agriculture, Fisheries & Conservation Dept., Government of Hong Kong Special Administrative Region.

Xing, F. W., S. C. Ng and L. K. C. Chau. 2000. Gymnosperms and angiosperms of Hong Kong. Mem. Hong Kong Nat. Hist. Soc. 23:21-136.

Xu, J. L. et al. 1985. Development and Evolution of Tidal Channels in Lingdingyang, Pearl River Estuary. Ocean Press, Beijing. (In Chinese.)

Xu, W. S. 1995. Raptors of China. China Forestry Publishing House. Beijing. (In Chinese.)
Yang, D. Y. 1997. A preliminary study on the sea mammals in Guangdong Province coastal waters and the protective measures. South China Sea Fisheries Research 14:69-70. (In Chinese.)

Young, L. 1993. The Ecology of Hong Kong Ardeidae (Aves) with Special Reference to the Chinese Pond Heron at the Mai Po Marshes Nature Reserve. Unpubl. PhD thesis, University of Hong Kong.

Young, L. 1994. Habitat use by herons and egrets (Ardeidae) at Mai Po Marshes Nature Reserve, Hong Kong. Unpubl. PhD thesis, University of Hong Kong.

Young, L. and D. S. Melville. 1993. Conservation of the Deep Bay Environment. pp 211-231 in: B. Morton (ed.) The Marine Biology of the South China Sea Vol. 1. Proceedings of the First International Conference on the Marine Biology of Hong Kong and the South China Sea, Hong Kong, 28 October - 3 November 1990. Hong Kong University Press, Hong Kong.

Young, L. and D. S. Melville. 1995. Environmental Research at the WWF Hong Kong Mai Po Marshes Nature Reserve. pp 58-68 in: Environmental Research in Pearl River and Coastal Areas. Guangdong Higher Education Press, Guangzhou.

Young, L. and M. W. Cha. 1995. The history and status of egretries in Hong Kong with notes on those in the Pearl River delta, Guangdong, China. Hong Kong Bird Report 1994: 196-215. Hong Kong Bird Watching Society, Hong Kong.

Yu, M. Y. et al. 1990. Environment and Resources for Increases in Aquaculture and Fisheries in Inshore Waters and Shores of Guangdong Province. Science Press, Beijing. (In Chinese.)

Yu, M. Y., M. Z. Li and C. Y. Liang. 1990. Report on Studies on Biota of the Intertidal Zone of Guangdong Province. Science Press, Beijing. (In Chinese.)

Zhan, H. G. 1996. Studies of fish community structure in the Pearl River Estuary and neighbouring waters. Nanhai Yanjiu yu Kaifa (South China Sea Research and Development) 4 of 1996:13-19. (In Chinese.)

Zhao, E. M. 1998. China Red Data Book of Endangered Animals: Amphibia & Reptiia. Science Press, Beijing.
Zheng, C. Y. 1989. Fish Fauna of the Pearl River. Science Press, Beijing. (In Chinese.)

Zheng, G. M. and Q. S. Wang. 1998. China Red Data book of Endangered Animals: Aves. Science Press, Beijing.

PERSONAL COMMUNICATIONS CITED

Paul Crow, Kadoorie Farm and Botanical Garden.

Charles Frew, marine ecologist.

Dr. Thomas A. Jefferson, cetacean biologist, Ocean Park Conservation Foundation.

Albert Leung, Swire Institute of Marine Science, Univ. of Hong Kong.

Dr. Ng Sai-chit, Dept. of Ecology and Biodiversity, Univ. of Hong Kong

Chris Molner, instructor, ProDive (Sino-USA).

Wang Pilie, cetacean biologist, Liaoning Marine Fisheries Research Institute, China.

Yau Mee-Ling, plant ecologist, Ecosystems Ltd.

Lew Young, WWF(HK).