9.1.1
This section identifies and evaluates the nature and
extent of potential impacts on marine ecological resources in the proposed
development area resulting from proposed reclamation and other marine works in
the Project. Several relevant
baseline studies and assessment reports are reviewed and both direct and
indirect impacts on marine ecology during construction and operation phases are
included in the assessment.
9.1.2
Where
necessary, field surveys have been undertaken to check current ecological
baseline conditions. Ecological importance of habitats and species potentially
affected by proposed works are identified and assessed. The scale and
significance of possible ecological impacts resulting from the Project are
evaluated, and necessary mitigation measures have been recommended. Residual
and cumulative ecological impacts are also identified and evaluated, and
ecological monitoring and audit requirements are discussed.
9.2.1
This section makes reference to the following HKSAR
Government ordinances, regulations, standards, guidelines and documents when
identifying ecological importance of habitats and species, evaluating and
assessing potential impacts of the proposed development on the ecological
resources:
·
Environmental
Impact Assessment Ordinance (EIAO) (Cap. 499) - aims to avoid, minimise and
control the adverse effects on the environment by designated projects through the application of the
environmental impact assessment process and the environmental permit system.
·
EIAO Technical
Memorandum on Environmental Impact Assessment Process (EIAO-TM) Annex 8 – provides
guidelines for the evaluation of the ecological impact caused by the designated
project. A list of criteria is provided for assessing the importance of habitat
/ species and the ecological impact.
·
EIAO-TM Annex 16 – describes the general approach and methodology for
assessment of ecological impacts arising from a project or proposal, to allow a
complete and objective identification, prediction and evaluation of the
potential ecological impacts.
·
EIAO Guidance Note No. 3/2002 - provides guiding principles on the
approach to assess the recommended environmental mitigation measures in
Environmental Impact Assessment (EIA) reports.
·
EIAO Guidance Note No. 6/2002 - provides some guidance on conducting
ecological assessment.
·
EIAO Guidance Note No. 11/2004 - introduces some general methodologies for
marine ecological baseline surveys.
·
Wild Animals
Protection Ordinance (Cap. 170) - designated wild animals are protected from
being hunted, whilst their nests and eggs are protected from injury, destruction
and removal. All birds and most
mammals, including marine cetaceans, are protected under this Ordinance. The
Second Schedule of the Ordinance, which lists all the animals protected, was
last revised in June 1997.
·
Protection of
Endangered Species of Animals and Plants Ordinance (Cap. 586) – to give effect
to the Convention on International Trade in Endangered Species of Wild Fauna
and Flora (CITES), the Ordinance strictly regulates the import, introduction
from the sea, export, re-export and possession or control of certain endangered
species of animals and plants and derivatives of those species scheduled in
Appendices I, II and III. The Ordinance came into effect on 1 December 2006.
·
Town Planning
Ordinance (Cap.131) - provides
for the designation of coastal protection areas, Sites of Special Scientific
Interest (SSSIs), Conservation Area, Country
Park, Green Belt or other
specified uses that promote conservation or protection of the environment.
·
The
Marine Parks Ordinance (Cap.476) and Subsidiary Legislation - allows for
designation, control and management of marine parks and marine reserves through
regulation of activities therein to protect, conserve and enhance the marine
environment for the purposes of nature conservation, education, scientific
research and recreation. The Ordinance came into effect on 1 June 1995.
·
The Protection of the Harbour Ordinance
(Cap.531) – bases on a
presumption against reclamation, the harbour is to be protected and preserved
as a special public asset and a natural heritage of Hong
Kong people.
·
The Water Pollution Control Ordinance
(Cap.358) – aims to
control water pollution in waters of Hong Kong.
Water control zones are designated with individual water quality objective to
promote the conservation and best use of those waters in the public interest.
The most updated water quality objective for the Victoria Harbour Water Control
Zone was revised in June 1997.
9.2.2
This section also makes reference to the following
international conventions and nearby national regulation:
·
International Union for Conservation of Nature and Natural Resources
(IUCN) 2006 Red Data Books - provides
taxonomic, conservation status and distribution information on threatened
species that have been evaluated using the IUCN Red List
Categories and Criteria. This system is designed to determine the
relative risk of extinction, and the main purpose of the IUCN Red List is to
catalogue and highlight those taxa that are facing a higher risk of global
extinction.
·
The PRC National
Protection Lists of Important Wild Animals and Plants - lists detailed Category I and Category II
key protected animal and plant species under Mainland Chinese Legislation. The
list was last updated in November 2002.
9.3.1
The proposed reclamation area would affect part of the
existing shoreline and seabed at Wan Chai District and Eastern District. In
general, the boundary of the Assessment Area is 500 m from the proposed reclamation area. The marine
ecological environment of the proposed development area, as shown in Figure 9.1, comprises
largely the Victoria
Harbour extending from
Wan Chai to North Point, including the Causeway Bay Typhoon Shelter (CBTS).
Literature review
9.3.2
The assessment of ecological impact on marine habitats
has been undertaken with reference to the previous baseline surveys and EIA
studies for other proposed projects in and within the vicinity of the proposed
reclamation area. These include the following:
·
Central Reclamation Phase III Studies - Site
Investigation, Design and Construction. Comprehensive Feasibility Study for
Minimum Option: Final Key issues and Initial Environmental Impact Assessment
Report (CRIII EIA report).
·
Agreement No. CE 52/95, Strategic Sewage Disposal
Scheme Environmental Impact Assessment Study (SSDS EIA study).
·
Agreement No. CE 74/98, Wan Chai Development Phase II
Comprehensive Feasibility Study (WDII EIA report).
·
Agreement No. CE 42/2001, Environmental and
Engineering Feasibility Assessment Studies in Relation to the Way Forward of
the Harbour Area Treatment Scheme – Water Quality, Ecological and Fisheries
Impact Assessment (HATS EEFS report).
·
Agreement No. CE 25/2002, Drainage Improvement in Northern
Hong Kong Island – Hong Kong West Drainage Tunnel
Environmental Impact Assessment Final Report.
·
CityU Professional Services (2003) Consultancy Study
on Marine Benthic Communities in Hong Kong.
Final Summer Field Survey Report. Submitted to AFCD.
·
EPD Water Quality in Hong Kong 2004.
·
AFCD Port Survey 2001-2002.
·
Agriculture, Fisheries and Conservation Department,
2004. Ecological Status and Revised Species Records of Hong Kong’s
Scleractinian Corals. Hong Kong: Agriculture,
Fisheries and Conservation Department, HKSAR.
·
Alan L.K. Chan, Choyce L.S. Choi, Denise McCorry,
Khaki K., Chan, M.W. Lee and Ang Put Jr. 2005. Field Guide to Hard Corals of Hong Kong. 1st Edition (Eds. W.C. Chan and
Edward Stokes). Friends of the Country
Parks and Cosmos Book Ltd, Hong Kong.
Ecological surveys
9.3.3
Field
surveys are considered necessary, where appropriate, to supplement and check
the validity of data collected through the literature review process. The field surveys for this assessment
include:
·
Ecological survey on intertidal and benthic habitats in and
within the vicinity of proposed reclamation area was conducted in January 2007.
The survey included spot-check reconnaissance dives on 29 representative line
transects and Rapid Ecological Assessment (REA) (DeVantier et al., 1998) at two spot-check
sites where signs of coral colonies were first observed during the spot-check
dives. Detailed survey plan and
methodology were presented in the Dive Survey Report (Appendix 9.1);
·
Intertidal communities surveys on artificial intertidal habitats within
the Project area were conducted in August 2006 by direct observation along the
shoreline. Fauna species and relative abundance were recorded and identified
according to Williams (2003). In addition, the natural coastline at the northern
part of Kellett Island was surveyed in January 2007 for
the intertidal assemblage using standard transect method. Detailed survey plan
and methodology were presented in the Intertidal Survey Report (Appendix 9.2).
·
Avifaunal survey was conducted in area of Victoria Harbour
and CBTS during August 2006 by fixed point direct observation (sight and call).
Identification of bird species was made reference to Viney et al. 2005;
Impact assessment methodology
9.3.4
Evaluation and assessment of potential impact on ecological
resources was conducted in accordance with the criteria and guidelines
specified in Annex 8 and Annex 16, respectively, of the EIAO-TM.
9.3.5
The significance of impacts was ranked as “low”, “moderate” or “high” based
on the criteria shown in Table 9.1. The description of the ranking is as
below:
9.3.6
Low - Impacts to
species or groups are assessed as “low” if the predicted impact would result in
a slight, and / or short-term reduction in the local population numbers or
geographic distribution of a species or group, but the species or group is
predicted to recover from the perturbation with no-long term adverse
impacts. Impacts to habitat are
assessed as “low” when the habitat is widely distributed locally and that no
rare or restricted species are found in the habitat.
9.3.7
Moderate – Impacts to
species or groups are considered “moderate” if the predicted impact probably
would result in non-recoverable and / or long-term reduction in population
numbers. However, the species in
question should be considered widely distributed or common, and abundant on a
local, regional or global scale.
Impacts to habitat are assessed as “moderate” if the habitat is of
limited local or regional distribution or declining in extent and that the
habitat has a potential of supporting fauna and / or fauna of conservation
importance.
9.3.8
High – Impacts to
species or groups are judged to be “high” if the predicted impact has an
adverse effect on species or groups which are rare, protected or of
conservation importance locally, regionally, or globally. Impacts to habitat are considered to be
“high” if the habitat in question is of limited local or regional distribution
or declining in extent and that it is generally considered by the scientific
community to be of local, regional or global importance to the support of rare
or restricted flora and /or fauna species.
9.3.9
If impacts on ecological resources are found to be
significant (that is, moderate or high), mitigation measures would be
recommended in accordance with the EIAO-TM Annex 16 and EIAO Guidance Note No. 3/2002. Impact mitigation would be sought in the
following priority: avoidance, minimisation, on-site compensation and off-site
compensation.
9.3.10
Impact avoidance generally consists of modifications
to the preferred development options, but may in some extreme cases require
abandonment of the project.
9.3.11
Impact minimisation includes any means of reducing the
scope or severity of a given impact, for example, through timing of
construction programme, modification in the design or ecological restoration of
disturbed areas following the completion of works.
9.3.12
Impact compensation will be recommended if the effect
on a given species or habitat is irreversible and attempts will be made to
compensate it elsewhere, for example, enhancement, creation of suitable
habitats or recreation of the habitat.
Compensation can be on-site or off-site.
9.4.1
The marine environment in the Assessment Area is
composed of the coastal water of Victoria
Harbour and the Causeway
Bay Typhoon Shelter (CBTS). Representative
photographs of marine environments are given in Appendix 9.3. In general, these
two areas are similar in water quality and sediment contamination as they are
hydrographically interconnected with each other. However, as CBTS is located
within an embayment with limited flushing, it is more vulnerable to pollution
than the coastal water in Victoria
Harbour.
Area of conservation interest
9.4.2
There are no ecological sensitive receivers, such as
SSSIs, Marine Parks/Reserves or other areas of ecological importance or
conservation interest, in and within the vicinity of the Assessment Area. As the proposed development will include
dredging and new reclamation, far field ecological sensitive receivers have
been identified. These potential off-site ecological sensitive receivers
include coral area located at Green Island, Little Green Island (6 km) and Junk
Bay (8 km).
Abiotic
Water
9.4.3
Under the Water Pollution Control Ordinance (Cap.
358), the Victoria
Harbour is within the
gazetted Victoria Harbour Water Control Zone. In the previous WDII EIA report
(Maunsell, 2001), marine water in the Victoria Harbour was identified as
turbid, hypoxic and highly eutrophic, that was due to the direct discharge of
wastewater into the harbour area with only preliminary treatment for the
discharged sewage (screening).
9.4.4
However, after the commissioning of the Stonecutters
Island Sewage Treatment Works (SCISTW) in 2002 under stage 1 of the Harbour
Area Treatment Scheme (HATS), water quality has improved significantly, especially
in the eastern harbour area. According to the EPD’s water quality monitoring
results, marine water in the Assessment Area (Station VM4 and VM5) is now less
turbid (turbidity 6.7-12.6 NTU), more oxygenated (dissolved oxygen 3.9-7.5 mg L-1),
and lower in inorganic nutrients (total nitrogen 0.14-0.61 mg L-1
and total phosphorus 0.02-0.08 mg L-1) (EPD, 2005).
9.4.5
However, the levels of E. coli (510-15000 cfu per 100 mL) and faecal coliforms (2100-34000
cfu per 100 mL) increased substantially over the decade, indicating increasing
faecal contamination (EPD, 2005).
9.4.6
In general, water quality in the Assessment Area has
been improved recently but the Victoria
Harbour provides a relatively poor
marine habitat compared to eastern and southern waters in Hong
Kong.
Sediment
9.4.7
The seabed in the Assessment Area is mainly composed
of soft bottom sediment with coarse particle size. The marine sediment in Victoria Harbour, according to EPD’s monitoring
results, is highly anaerobic (electrochemical potential -409mV to -258 mV) due
to high organic loading from sewage over the years. The sediment is toxic with
high level of ammonia nitrogen (15-86 mg L-1) and total sulphide
(170-1700 mg kg-1). It is also highly contaminated with copper
(84-250 mg/kg) and silver (3.0-11 mg/kg) which exceed the Lower Chemical
Exceedance Level (LCEL) or Upper Chemical Exceedance Level (UCEL), as defined
in the ETWB Technical Circular (Works) No. 34/2002 (EPD, 2005).
9.4.8
Previous WDII EIA Report (Maunsell, 2001) pointed out
that numerous ecological studies have been conducted in the Victoria Habour,
and those have usually determined its polluted nature using single species or
indicator groups (e.g. barnacles, Chan et
al., 1990; Rainbow and Smith, 1992; Blackmore, 1999; fish, Kwan, 1999 and
mussel, Nicholson, 1999).
9.4.9
A recent sediment toxicity test was carried out under
the HATS EEFS study and sediments collected from Victoria Harbour (Station XN4
and VM7) were highly toxic to benthic amphipod Leptocheirus plumulosus, resulting in very low survivalship of
9-31% only (CDM, 2004).
Biotic
9.4.10
The study area comprises several broad marine habitats
including:
·
Benthic habitat on soft bottom substratum of the Victoria Harbour.
·
Intertidal habitats on artificial seawall and mimic
rocky shore.
·
Intertidal habitats on natural rocky shore of northern
Kellett Island.
·
Subtidal habitat in Victoria Harbour.
·
Feeding ground for waterbirds in CBTS near A King
Shipyard.
9.4.11
Representative photographs of some identified marine
habitats are presented in Appendix 9.4.
The baseline ecological conditions of different marine habitats in the
Assessment Area are described below.
Soft bottom benthos
9.4.12 Previous WDII EIA
report summarised the findings in Thompson and Shin (1983) and showed that
benthic assemblages in the Assessment Area were typically of low diversity and
abundance, and community structure was largely dictated by organic pollution
from sewage discharges in the past.
As only a limited number of hypoxia tolerant species can survive the
bottom conditions within the study area region, fauna was dominated by
opportunists such as bivalves and polychaetes.
9.4.13 Dominant
polychaetes include Minuspio cirrifera
and the best-known marine organic enrichment indicator Capitella capitata.
These polychaetes may be indicators of moderate and severe organic
pollution, respectively. The moderately pollution tolerant bivalve Ruditapes philippinarum (stated as Tapes philippinarum) was also found
dominant in the benthic infaunal population in the same study (Thompson and Shin, 1983).
9.4.14 Another field survey
of soft bottom benthic organisms at the seabed in the Victoria Harbour
near the Central District conducted for CRIII EIA Study (Atkins China Ltd.,
1999) was also reviewed in previous assessment. This field survey indicated
that the soft bottom marine environment in the Victoria Harbour
was polluted and lacked a macroinvertebrate community.
9.4.15 The field survey
carried out for the SSDS EIA study also confirmed a very low species diversity
and evenness for benthic assemblages in Victoria Harbour
and was indicative of stressful environment for benthos (Binhai, 2000).
9.4.16 A recent study on
marine benthic communities in Hong Kong showed that a coarser sediment benthic
group was found in Victoria Harbour (Station 53 & 54) as compared to
eastern and southern waters, with lower species diversity and evenness resulted
(CityU, 2002).
9.4.17 This study showed
that the benthic communities in Victoria
Harbour comprised of
mainly polychaete (Cirratulus sp., Schistomeringo rudolphi, Dodecaceria sp., Naineris sp., Sigambra
hanaoka and Prionospio sp.),
oligochaete (Thalassodrilides gurwitchi),
bivalve (Ruditapes philippinarum) and
crustacean (amphipod Cheiriphotis
megacheles) (CityU, 2002). It indicated a distinct benthic composition
which is characterized by species strongly adaptable to eutrophic environment.
9.4.18 Other recent survey
for HATS EEFS study on benthic assemblages in Victoria Harbour
near North Point (Station VM2 and XM4) also indicated that the benthic
assemblage was dominated by polychaeta (Naineris
sp., Glycera sp., Prionospio sp.), mollusca (Ruditapes sp.) and crustacea (Corophium sp.). Bivalve Ruditapes sp. is the most abundant (44%)
fauna, comprising 95% of the whole benthic assemblage biomass. Although it is a
commercial species, the conservation value is not high. It was noted that the
benthic community structure has been relatively stable over the years and so
quite robust to environmental disturbance (CDM, 2004).
Intertidal Communities (Artificial)
9.4.19
Intertidal seashore habitats in the Assessment Area
mostly comprise of the artificial vertical seawalls, with small portion of
man-made sloping seawalls and rockfills (rocky shores ‘mimic’ natural habitat)
at the Wan Chai Ferry Pier and around the HKCEC.
9.4.20
Previous WDII assessment reviewed a number of
literatures and indicated that fauna presented in seawalls and rockfills were
largely restricted to encrusting sessile organisms such as bivalves, molluscs
and barnacles (Morton and Morton, 1983; Lee, 1985; Lee and Morton, 1985).
9.4.21
Fauna commonly encountered included molluscs such as
the common neogastropod (Thais clavigera)
and the pollution-tolerant bivalve (Perna
viridis), as well as encrusting crustaceans such as barnacles (Balanus spp., Tetraclita squamosa and Capitulum
mitella) and the ubiquitous mobile isopod (Ligia exotica) (Morton
and Morton, 1983; Lee, 1985; Lee and Morton, 1985).
9.4.22
Flora is mostly restricted to algae that are either
organic or nutrient enrichment indicators such as Ulva spp. and Cladophora (Morton
and Morton, 1983; Ho, 1987; Moore, 1990).
9.4.23
A recent intertidal fauna survey on artificial
seawalls and rockfills within the Assessment Area was carried out in August
2006 to confirm the validity of the literature results. The list of intertidal
fauna is summarised in Appendix 9.5.
Compared to the past records, similar biotic assemblages on artificial
intertidal habitats around HKCEC, CBTS and the shoreline of City Garden
in North Point were found in current survey and the intertidal composition in
the Assessment Area was generally consistent with the past recorded results.
9.4.24
The artificial seawalls in the Assessment Area were
found to be generally inhabited densely by few species of sessile encrusting
fauna, including chiton (Acanthopleura
japonica), barnacle (Tetraclita
squamosa) and bivalve (Saccostrea
cucullata). The only mobile species found on the artificial seawalls were
the common Sea Slater (Ligia exotica) and topshell (Monodonta labio). All
of them are common local intertidal species with low conservation interest.
9.4.25
It was found that the mimic rocky shores located at
the Wan Chai Ferry Pier and the shoreline of the HKCEC provided a more diverse
and abundant intertidal community compared with the vertical and sloping
seawalls. Limpet (Patelloida saccharina)
and small crab, together with the species described in 9.4.23,
were recorded in the rockfill habitats.
9.4.26
In the current study, encrusting algae (Pseudulvella applanata and Hildenbrandia sp.) were recorded on the
surface of artificial vertical seawalls in the Assessment Area. No erect algae
or higher flowering plant was found during the recent survey.
Intertidal Communities (natural)
9.4.27
Part of the coastline found at the northern part of
the Kellett Island is the only natural coastline
within the study area. The natural coastline on Kellett Island
is a typical sheltered rocky shore subjected to only slight wave action.
9.4.28 Field survey
conducted for the WDII EIA study indicated that the sheltered rocky shore
communities were composed of large quantities of topshell (Monodonta austrailis) dominating the lower shore and periwinkles (Nodilittorina millegrana), dominating
the upper shore (Maunsell, 2001).
9.4.29 Other intertidal
species including Stalked Barnacle (Pollicipes
mitelia), Acorn Barnacle, (Tetraclita
squamosa), common chiton (Liolophura
japonica) and limpet (Cellana toreuma)
were occasionally observed. In
general, the species diversity and abundance were relatively low compared to
other natural shoreline in Hong Kong. No rare
species or species of conservation value were observed in this survey
(Maunsell, 2001).
9.4.30 A recent intertidal
survey on the shoreline of northern Kellet
Island was conducted in
January 2007 in order
to provide more detailed and updated information on the existing ecological
assemblage profile in this natural habitat. Detailed survey methodology, location,
result and discussion are provided in the Intertidal Survey Report (Appendix 9.2). Figure 1 of the Appendix 9.2
indicates the two surveyed locations within the natural shoreline where
quadrats of 0.5 m x 0.5 m dimension were laid at 1 m interval along 10 m transects which extended from high tide mark to
low tide mark. Epifauna within each quadrats were identified, enumerated and
recorded.
9.4.31 Recent survey
revealed that natural coastline at the northern Kellet Island
was limited to small area of less than 20 m x 100 m
dimension only with natural substrata of large boulders, cobbles and bedrocks
and some old concretes. The nearby intertidal habitats were mainly composed of
artificial seawalls and rock armours and this habitat was subjected to high
level of disturbance from past construction and reclamation works at nearby
areas.
9.4.32 A total of seven
species were recorded during recent survey and their abundances were shown in Table 1 of Appendix 9.2. Similar composition and distribution pattern of
intertidal communities were observed during recent survey compared with those
reported in WDII EIA Study. Periwinkles (Nodilittorina
millegrana) and topshell (Monodonta
austrailis) were the most common species recorded on both transects with N. millegrana dominating the upper shore
and M. austrailis dominating the
lower shore. Other intertidal species including limpet (Cellana toreuma), Nerite (Nerita chanaeleon), Stalked Barnacle (Capitulum mitella)
and Acorn barnacle (Tetraclita
squamosa) were also recorded.
All the recorded species are common in most of the shorelines in Hong Kong and no species of conservation
importance or nursery/breeding activities was observed in this area.
Subtidal fauna
Marine mammals
9.4.33
Literature review has shown that there were no
sightings of marine mammals within the Assessment Area. One of the most
important marine mammals in Hong Kong waters is the Chinese White Dolphin (Sousa chinensis) which was only seen in
the western estuarine waters in Hong Kong including outer Deep Bay, north,
south, east Lantau and west Lamma (Hung, 2006). The other common marine mammal
Finless porpoise (Neophocaena phocaenoides) was also never
reported in the Victoria Harbour and only occurs in the eastern and southern
waters of Hong Kong (Jefferson, 2001). There is
no significant record of such marine mammals with high conservation interest
within the Assessment Area.
Corals
9.4.34 In Hong Kong, the
richest coral communities are found in the eastern part where water is free
from the influence of estuarine water from the Pearl River.
As water in Victoria
Harbour was turbid with
high level of suspended solids, it was unsuitable for coral to survive and
colonise there. Based on the review
on a number of previous literatures, there was no significant record of coral
reported within the Assessment Area.
9.4.35 Literature review
indicated that the nearest soft corals and gorgonians are located at Green
Island and Little Green Island about 6 km
west from the reclamation area. A low coverage of black coral of Anthipathes sp. was also found in Green Island
(TDD, 1998). In general, soft coral and gorgonians are more resistant to turbid
waters than hard coral as they do not contain symbiotic algae zooxanthallae and
do not require light penetration for photosynthesis. Therefore, they are more widely
distributed in Hong Kong and are also found in
areas of higher turbidity.
9.4.36 The EIA study for
Tseung Kwan O Further Development also identified the presence of small
colonies of hard corals with sparse cover of soft corals and gorgonians found
in Chiu Keng Wan located at the northwestern Junk Bay,
which is about 8 km to the
east from the Project area (Maunsell, 2005).
9.4.37
Recent
dive survey for HASTS EEFS Study also indicated that the shallow water of Joss
House Bay and north-west Tung Lung Chau (over 10 m east of the reclamation area) supported
reasonably diverse but low cover hard coral communities. However, the same
study showed that there were no hard corals or soft corals observed in the
North Point areas (CDM, 2004).
9.4.38 Due to lack of
information on presence of coral communities in and within the proposed
reclamation areas, recent dive survey was carried out during January 2007 in order to provide sufficient and
updated information for the evaluation of any potential impact to coral arising
from the proposed development. Details on the methodology, surveyed area,
results, discussion and recommendation are provided in the Dive Survey Report (Appendix 9.1).
9.4.39 Spot-check reconnaissance dives were first
conducted to identify the extent of hard substrate with an emphasis on gaining
an overview of coral occurrence within and adjacent to the proposed reclamation
area. Areas with corals identified in spot-check dives were then further
surveyed using REA technique along 100 m
transect. Figure 1 & 2 of Appendix 9.1 indicate the areas covered
by the spot-check dives and the locations where the REA transects deployed.
9.4.40 As illustrated in Table 2 of Appendix 9.1, 29 representative line transects of totally 4680 m were surveyed in spot-check dives.
The underwater visibility at all surveyed sites were generally poor (< 2 m). The maximum water depth in all the
surveyed sites ranged from 3 m
to 8 m. Bottom substrata
were mainly composed of muddy or sandy seabed with hard substrata rubble
seawalls for most of the surveyed sites while rock or boulder was also found at
Site 3, 6, 13, 14 and 18-21.
9.4.41 In all of the
surveyed sites, the seabed quality is generally poor with limited marine life
observed. Only one species of hard coral (Oulastrea
crispata) and one species of octocoral (gorgonian Echinomuricea sp.) were found at Site 13 and Site 27 respectively.
But they are all small in size, sparsely distributed and in very low coverage
(< 1%). Neither soft coral nor black coral was identified during the
spot-check dives.
9.4.42 More detailed REA
surveys were then carried out at Site 13 and Site 27. Substrata at Site 13 were
mainly composed of muddy and sandy bottom with boulders while Site 27 comprised
muddy bottom with hard substrata of rubber seawalls.
9.4.43 At site 13, only
sparse coverage (1-5%) of totally 18 colonies of single hard coral species (Oulastrea crispata) was recorded during
the REA survey. Most of the colonies were attached on the small rocks or
boulders less than 50 cm in
diameter in the ex-Public
Cargo working Area (PCWA) basin near
the pier of the Hong Kong Yacht Club. All the colonies found at Site 13 were in
fair health condition but in small size ranged from 3
cm to 8 cm
in diameter. Oulastrea crispata has a wide range
of adaptations to different environmental conditions (including those
unfavourable to corals) as well as geographic locations, which is a result of
its stress-tolerant ability (Chen, et al.
2003). With an opportunistic life history trait, a wide range of reproductive
strategies and surface-orientation independent growth, O. crispata is able to colonise a variety of substrata and to
flourish as a pioneer coloniser of newly immersed structures (Lam, 2000a & 2000b). It is common and
widespread in Hong Kong marine waters,
especially those more turbid and harsh environment in the western waters (Chan,
et al. 2005).
9.4.44 Very low coverage
(1-5%) of only one colony of octocoral (gorgonian Echinomuricea sp.) was found at Site 27 during the REA survey. It
was located on the seawall at the North Point Shoreline next to a public pier
which is about 250 m
away from the CBTS. The colony found was small in size (25 cm in diameter) and in fair condition. Echinomuricea sp. is a common gorgonian
coral found in Hong Kong water, especially in those turbid waters at southern
and western part of Hong Kong.
Feeding ground in CBTS
9.4.45 Recent avifaunal
survey revealed few bird species presented in the Assessment Area and list of
birds was summarised in Appendix 9.6.
The locations of species of conservation interest recorded in the Assessment
Area were indicated in Figure 9.1.
9.4.46 It was found that
CBTS, particularly the area near the A King Shipyard, is a feeding ground for
ardeids of conservation interest including Little Egret (Egretta garzetta), Great Egret (Ardea
alba) and Black-crowned Night
Heron (Nycticorax nycticorax). The
other species of conservation interest found during recent survey included the
White-throated Kingfisher (Halcyon
smyrnensis) and Black Kite (Milvus migrans).
All wild birds are protected under local law and the conservation status of the
recorded species of conservation interest is discussed in details below.
9.4.47 A total of 36
Little Egret (Egretta garzetta) was found foraging and feeding in the
coastal water of Victoria
Harbour and CBTS. Although Little Egret is a common ardeid which is widely
distributed in the coastal waters throughout Hong Kong,
it is considered to be a species of conservation interest regionally due to its
restricted site of breeding and roosting (Fellowes et al., 2002).
9.4.48 A Great Egret (Ardea alba) was also observed forage and feed together with the Little Egret
population at the CBTS near A King Shipyard. Although this species is a common
resident and winter visitor in Hong Kong, the
Great Egret is considered to be of conservation interest regionally due to its
restricted breeding and roosting area (Fellowes et al., 2002).
9.4.49 Six Black-crowned
Night Heron (Nycticorax nycticorax)
(including one juvenile) were also
recorded foraging and feeding at the CBTS near A King Shipyard. This ardeid is a
common local resident and winter visitor in Hong Kong.
Due to its restricted breeding and roosting area, it is listed as a species of
conservation interest locally (Fellowes
et al., 2002).
9.4.50
A total of four Black Kite (Milvus migrans) was observed at flight above the Victoria Harbour
and CBTS during recent survey. This species
is a common resident and winter visitor in Hong Kong
(Carey et al., 2001). Black Kite is a Category II
protected species under Mainland Chinese Legislation. Although locally very common, Kites are considered as
species of conservation interest regionally due to its restricted number of
nesting and roosting sites (Fellowes et al., 2002), with the current
breeding population believed to be about 30 pairs (Carey et al., 2001).
9.4.51 A White-throated
Kingfisher (Halcyon
smyrnensis) was recorded in the CBTS near A King Shipyard. This species is a local
common resident and is widely distributed in the coastal areas throughout Hong Kong (Carey et
al. 2001). It is listed as species of conservation interest locally due to its restricted breeding and roosting
site (Fellowes et al. 2002).
Ecological
Importance
9.4.52 Based on the
available literature and discussion presented above, the ecological values of
marine resources present within the Assessment Area have been assessed and
evaluated. This has been determined in accordance with the EIAO-TM Annex 8
Table 2 criteria and is shown in Tables
9.1.
Table 9.1 Criteria
and Evaluation of Ecological Importance of Marine Habitats in the Assessment
Area.
|
Criteria
|
Soft bottom habitat
|
Intertidal habitat (artificial)
|
Intertidal habitats (natural)
|
Subtidal
habitat
|
Feeding ground in CBTS
|
|
Naturalness
|
Subjected to extensive
anthropogenic disturbance
|
Man-made habitat
|
Basically natural but its
naturalness were partially affected by past reclamation and construction.
|
Highly disturbed by marine
traffic, subjected to extensive water pollution
|
Disturbed by marine traffic and
human activities
|
|
Size
|
Large, 15 ha
|
Large, 1 km long
|
Small, less than 100 m long
|
Large, 15 ha
|
Large, 16 ha
|
|
Diversity
|
Low, mainly dominant by
pollution-tolerant fauna
|
Low, mainly composed of few
intertidal fauna
|
Low, mainly composed of few
intertidal fauna
|
Low, species confined to those
resistant to polluted water
|
Low, only few avifaunal species
found
|
|
Rarity
|
No rare species found
|
No rare species found
|
No rare species found. But this coastline is one of the
remaining natural habitats on the north shore
of Hong Kong Island
|
No rare species found but only one
species of common hard coral and one species of common gorgonian were
recorded
|
No rare species recorded but
species of conservation interest including Little Egret, Great Egret,
Black-crowned Night Heron, Black Kite and White-throated Kingfisher were
found
|
|
Re-creatability
|
High
|
Very High
|
Moderate
|
High
|
High
|
|
Fragmentation
|
The habitat is not fragmented.
|
The habitat is highly fragmented.
|
The habitat is fragmented.
|
The habitat is not fragmented.
|
The habitat is not fragmented.
|
|
Ecological linkage
|
Not functionally linked to
any highly valued habitat in close proximity.
|
Not functionally linked to
any highly valued habitat in close proximity.
|
Not functionally linked to
any highly valued habitat in close proximity.
|
Not functionally linked to
any highly valued habitat in close proximity.
|
Not functionally linked to
any highly valued habitat in close proximity.
|
|
Potential value
|
Very low
|
Very low
|
Low
|
Low
|
Low
|
|
Nursery ground
|
No significant record.
|
No significant record.
|
No significant record.
|
No significant record.
|
No significant record.
|
|
Age
|
NA
|
NA
|
NA
|
NA
|
NA
|
|
Abundance / Richness of wildlife
|
Low for abundance and species
richness
|
High for abundance but low for
species richness
|
High for abundance but low for
species richness
|
Low for abundance and species
richness
|
Low for abundance and species richness
|
|
Ecological importance
|
Very low
|
Very low
|
Low
|
Low
|
Low
|
9.4.53
Species
of conservation interest recorded in the Assessment Area are evaluated in Table
9.2 below.
Table 9.2 Species
of Conservation Interests recorded in the Assessment Area.
|
Species
|
Location
|
Protected
Status 1
|
Distribution & Rarity 2
|
|
Coral
|
|
Hard
coral
Oulastrea crispata
|
Ex-PCWA Basin near the pier of the Hong Kong
Yacht Club
|
Listed in
Cap. 586
|
Common
in Hong Kong waters.
|
|
Gorgonian
Echinomuricea sp.
|
Seawall
next to a public pier which is about 250
m away from the CBTS
|
-
|
Common
in Hong Kong waters.
|
|
Avifauna
|
|
Black-crowned
Night
Heron
Nycticorax nycticorax
|
CBTS near A King Shipyard
|
-
|
Locally
common, but with limited number of breeding sites in Hong
Kong. Local concerned conservation species.
|
|
Little
Egret
Egretta garzetta
|
CBTS near A King Shipyard and the Victoria Harbour
|
Listed in
Cap. 586
|
Locally
common, but with regional concerned conservation interest for its restricted
breeding sites in regional area.
|
|
Great
Egret
Ardea alba
|
CBTS near A King Shipyard
|
Listed in
Cap. 586
|
Locally
common, but with regional concerned conservation interest for its restricted
breeding sites in regional area.
|
|
White-throated
Kingfisher
Halcyon smyrnensis
|
CBTS near A King Shipyard
|
-
|
Common
resident in Hong Kong, but is local
concerned conservation species for its restricted breeding site recorded.
|
|
Black
Kite
Milvus migrans
|
CBTS near A King Shipyard and the Victoria Harbour
|
Listed in
Cap.586 and Category II protected species under Mainland national legislation
|
Common
resident and winter visitor in Hong Kong.
Regional concerned conservation species.
|
Note 1: All
wild birds in Hong Kong are protected under
Ordinance Cap.170
Note 2: Information taken from various
sources including Viney et al. (2005),
Carey et al. (2001), Fellowes et
al. (2002) and Chan et al. (2005).
9.4.54
Soft bottom seabed and artificial interidal habitat
are considered as very low ecological importance. This is based on the
considerations of their highly disturbed nature, low species diversity and absence
of rare species found in current ecological impact assessment.
9.4.55
Ecological value of natural intertidal habitat found
in northern coastline of Kellet Island is ranked of low level due to its small size,
low species richness and partial loss of naturalness by past reclamation and
construction works, though it is scarce natural intertidal habitat existing in
the northern Hong Kong
Island.
9.4.56
The colonies of hard coral and gorgonian found in the
subtidal habitat are low in species richness and abundance, small in size and
they are common species which can tolerant to more turbid water and can be
found in many locations of Hong Kong waters. In view of the poor habitat
quality (e.g. high SS level, low light intensity, etc) for coral colonization
compared with other locations in Hong Kong
waters, the subtidal habitat is considered as low in ecological importance.
9.4.57
Although feeding ground in CBTS serves as a foraging
area for some waterbirds and other avifaunal species of conservation interest
in local or regional area due to their restricted breeding number and site
recorded, the habitat size, species diversity and abundance are relatively low.
Similar alternative feeding grounds for ardeids and other bird species of
conservation interest are also found available in the vicinity such as the Kwun
Tong Typhoon Shelter, To Kwa Wan Typhoon Shelter and Yau Ma Tei Typhoon
Shelter. Therefore, this habitat is not considered as an important feeding
ground for the bird population and its ecological significance is ranked as
low.
9.5.1
Impacts to marine ecological resources may occur
during the construction and operational phases. The impacts may be derived from
direct loss of the habitats or indirect disturbance through changes to key
water quality parameters.
Construction phase
Direct
impact
9.5.2
Potential
direct impacts on marine ecology arising from the proposed development would
include loss
of habitats and the associated marine species due to dredging and filling
activities. This would include:
·
Permanent loss of approximately 12.7 hectares of soft
bottom seabed and subtidal habitat along the Wan Chai and North Point Shoreline
for land reclamation.
·
Temporary loss of approximately 7.9 hectares of soft
bottom seabed and subtidal habitat within ex-PCWA basin and CBTS for temporary
reclamation, but area near A King Shipyard is not included in the reclamation
plan and so no direct loss of feeding ground for waterbirds would be resulted.
Temporary loss of approximately 0.4ha
of soft bottom seabed and subtidal habitat at the eastern end of Wan Chai
Shoreline for temporary reclamation.
Temporary loss of approximately 2.4ha
of soft bottom seabed and subtidal habitat for the temporary typhoon shelter.
·
Permanent loss of approximately 1 km long artificial intertidal habitat due to
reclamation work.
·
Temporary loss of approximately 850 m long artificial intertidal habitat for temporary
reclamation.
Indirect impact
Changes in water quality
9.5.3
Potential indirect impacts to the marine habitats and
the associated fauna would include changes in water quality due to dredging
activities of seabed sediment and potential site run-off from land-based
construction works.
Elevation of suspended solid (SS)
9.5.4
Possible
indirect impact on subtidal habitat may include water quality deterioration due
to siltation effects during the marine works. Marine fauna especially sessile
filter feeders are susceptible to deleterious impacts from sedimentation
through smothering and clogging of their respiratory and feeding apparatus.
Similarly, more turbid water may reduce the amount of light reaching beneath
the water surface, which may also be detrimental to marine flora and fauna. This may result in
both direct (e.g. mortality) and indirect (e.g. slow growth rate, low in
reproductive success rate) impacts on marine life and may eventually cause the
reduction of population size of marine assemblage. Potential secondary impact
on the waterbird population may be resulted due to the reduced food
availability caused from the dredging works of this Project.
9.5.5
To
assess the impacts associated with elevated SS, the assessment was based on
compliance with the statutory Water Quality Objectives (WQO) for concerned
Water Control Zones, which are set for among other reasons, to offer protection
for marine ecological resources. Water quality modelling predictions were
analyzed for compliance with the WQO through comparison of worst case
scenario’s 15-day depth-averaged SS level against baseline levels. Using this criterion, if the elevation
in SS levels exceeds 30% above ambient baseline conditions, adverse impacts on
marine ecology, may be predicted and suitable mitigation pursued.
9.5.6
There
are no WQOs regarding sedimentation rates. To assess impacts due to sediment
deposition on far-field ecological sensitive receivers, the sedimentation rate
of not exceeding 100 mg cm-2 per day (or 0.1 kg m-2 per day) which was also adopted
in other EIA studies in Hong Kong for ecological resources conservation (Hyder,
1997; ERM, 2001; Black & Veatch, 2006), is considered as suitable for coral
protection in this study.
Release of contaminants and nutrients
9.5.7
As
bottom sediment is disturbed during dredging activities and particles released
into the water column, organic and inorganic substances contained in the
sediment may be released to the water column. Released substances may cause
toxic effects to marine fauna.
9.5.8
In
addition, the release of inorganic substances may cause eutrophication and
algal bloom in the construction area. Oxidation of dead algae may use up some
of the oxygen in the water. If
oxygen levels are depleted to low levels, benthic organisms unable to tolerate
such conditions may suffer hypoxia-induced mortality and / or stress including
reduced feeding and growth rate.
The WQO standard that the average-depth and bottom water DO should
remain above 4 mg/L and 2 mg/ L respectively for 90% of the time was adopted.
Disturbance impact
9.5.9
Marine construction and dredging activities within the
existing CBTS may cause disturbance impacts on the associated waterbird population and other avifaunal
species of conservation interest due to increase of background noise and human
activities.
Operation phase
Direct
impact
9.5.10 There is no direct
ecological impact on marine resources expected during the operation phase of
the Project.
Indirect
impact
Change in tidal flow pattern
9.5.11 Potential indirect
impacts caused by changes in hydrographic regime of the harbour and the
subsequent tidal flow pattern may cause changes in water quality.
Disturbance impact
9.5.12 Because the proposed development plans of
the Project include reprovision of Wan Chai Ferry Pier, other recreational port
facilities near the ex-PCWA basin and the floating Tin Hau Temple on-shore to
the site of the existing A King Shipyard, increased marine traffic and human
activities during the operation phase is anticipated and potential disturbance
impact to marine resources and associated wildlife would be expected.
Construction
phase
Direct
impact
Habitat
loss
9.6.1
Direct impacts to the marine ecological resources
would include unavoidable habitat loss due to the dredging and filling
activities in the Assessment Area.
The reclamation works would lead to the permanent loss of approximately
12.7 hectares of soft bottom habitat and subtidal habitat. Reclamation of
coastal area would also cause permanent loss of approximately 1 km of artificial intertidal habitat
near the HKCEC and at the North Point Shoreline.
9.6.2
Temporary habitat loss of approximately 10.7 hectares
soft bottom and subtidal habitats as well as 850 m long artificial intertidal habitat would also
occur at the areas of ex-PCWA basin, CBTS and at the eastern end of Wan Chai
shoreline where temporarily reclamation was proposed for the Trunk Road
construction, and at the area of the temporary typhoon shelter. However, the
identified feeding ground for waterbirds near the A King Shipyard and the
existing natural shoreline at the Kellett
Island will remain intact
during construction. No direct loss of feeding ground for waterbirds and
natural intertidal habitat would be resulted in this Project.
9.6.3
As discussed in Section 9.4, soft bottom seabed,
intertidal (artificial) and subtidal habitat in the Assessment Area are ranked
as low ecological importance (very low to low value). In addition, temporary
loss of habitats due to temporary reclamation would be reinstated after the
construction works and similar assemblages of flora and fauna are expected to
re-colonise. Indeed, the removal of the contaminated sediments by dredging for
the temporary reclamation and the reinstatement of the seabed material would
provide improved seabed habitat condition.
Therefore, permanent and temporary loss of these habitats would not
result in adverse impact on the marine ecological system in and within the
vicinity of the Project area.
9.6.4
Nevertheless, it is recommended to avoid direct loss
or damage of any species of conservation interest within the proposed
reclamation areas as far as possible. The species of conservation interest
found within these affected habitats include only a single species of common
hard coral (Oulastrea crispata) and a
common gorgonian colony (Echinomuricea
sp.). Those 19 existing coral colonies found at the coastlines within ex-PCWA Basin (Site 13) and along seawall at
North Point (Site 27) (Figure 1 & 2
of Appendix 9.1) are
attached to small and manually movable boulders and are practically feasible
for translocation. In addition, the
recorded species are not competitive and aggressive in nature (Lam, 2000a),
these species are not expected to have
any negative pressure on the other existing corals in the coral
translocation recipient site and it is therefore considered suitable for
translocation in the ecological point of view. It is therefore recommended
to translocate all these existing coral colonies found at Site 13 and 27 to
other suitable location such as Junk
Bay where similar
hydrographic condition and healthy coral communities of same coral species have
been recorded.
9.6.5
In addition, about 1 km vertical wave absorbing seawalls would be
reconstructed along the shoreline of the newly reclaimed area around the HKCEC
and at North Point. Colonisation of intertidal flora and fauna on the newly
formed seawalls would recover the impact of intertidal habitat loss due to the
construction works.
9.6.6
Overall, all the marine habitats that would be
permanently or temporarily lost due to this Project are all of very low or low
ecological values and taking into account of all the mitigation measures
proposed including coral translocation and reprovision of newly constructed
seawalls, no adverse ecological impact on marine habitats and associated
wildlife is expected.
Indirect impact
Changes in
water quality
9.6.7
Indirect impacts on the marine ecology would be
associated with changes of water quality due to dredging and reclamation
activities, and site runoff from land-based construction works.
Elevation
of Suspended Solid (SS)
9.6.8
Dredging and reclamation activities would temporarily
elevate the suspended sediment level and create sediment plumes. Benthic
epifauna could be susceptible to the effects of increased sediment loads. Effects could be lethal or sublethal
through reduction in survivalship, growth rate and reproductive potential due
to stress incurred by the need to constantly flush out deposited material. The effects of sedimentation on
organisms depend on several factors, such as species tolerance to suspended
solids, life modes of organisms (sessile or free-swimming) and water movement. Potential
secondary impact of reduced food availability on waterbirds population and other
avifaunal species of conservation interest recorded in the assessment
area may be resulted if reduction of population size of marine assemblage
occurs. However, considering there are a number of similar feeding areas within
the Harbour area, the affected waterbirds are expected to displace to the
nearby alternative feeding grounds for foraging and no adverse impact on the
associated waterbirds population and other avifaunal species of conservation
interest
is expected.
9.6.9
Based on the prediction of the construction phase
water quality modelling (see water impact assessment), potential water quality
impact due to elevation of SS would occur at coastal waters of the Victoria Harbour. It is
predicted that impacts to intertidal and subtidal assemblages immediately
outside of the dredging and reclamation sites would occur during the
construction phase because the elevation of SS is predicted to be more than 30% increase from ambient level at several locations. However, implementation of the proposed mitigation
measures as suggested in the water quality assessment could effectively
minimize this impact to less than 10 mg/L SS elevation in the assessment area.
As suggested in Section 9.6.4, coral colonies
found at
the coastlines within ex-PCWA
Basin and along seawall
at North Point would be translocated to other locations prior to the
commencement of proposed works and therefore these coral colonies would not be
affected by this impact. Considering that the intertidal and subtidal
communities identified in the Assessment Area are of generally very low
ecological value and in view of the impact of suspended solids elevation is
temporary, no adverse indirect ecological impact is anticipated.
9.6.10
Impact is not expected to occur at the far field
ecological sensitive receivers including the coral areas located in the
vicinity of Green Island, Little Green Island and Junk Bay. Sedimentation rate and elevations of SS
at these locations are predicted to be less than
0.1 kg
m-2 per day and 2 mg L-1 respectively under the worst case
scenario. An elevation of this
magnitude is very small and the total SS level is compliant with the WQO
criteria for these areas. Thus, it
is expected that adverse impacts to these areas arising from elevated SS levels
would not occur.
9.6.11 The predicted
elevation of SS at coastal water of the Kellet Island
is less than 10 mg/L under the worst case scenario, implementation of proper
mitigation measures could minimise this impact. In addition, existing man-made vertical
seawalls along the shoreline of Kellet
Island also provide
partial protection to the intertidal fauna assemblage, no adverse impact to the
present intertidal community is expected.
Release
of contaminants and nutrients
9.6.12 As the sediment in
the Project area is contaminated with heavy metals and organic pollutants,
turbulence caused by dredging activities could release these substances to the
water column. Increase of toxic substances in water could cause lethal or
sublethal effects to subtidal fauna. Degree of toxic level depends on numbers
of factors e.g. species tolerance, contaminant levels, water flow rate, etc.
9.6.13 An indication of
the likelihood of release of contaminants from the marine sediment during
dredging is given by the results of the elutriation tests from the laboratory
testing conducted under the Phase I and Phase II marine site investigation (SI)
works (see water impact assessment, S.5.7.30 –
5.7.48 for details). The elutriate tests indicated that only the levels of
silver and mercury measured in two isolated elutriate samples would marginally
exceed the WQO standards. Although exceedences were measured in the elutriate
samples, it is expected that any release of contaminants during dredging would
be quickly diluted by the large volume of marine water within the construction site. Based on the detected highest
concentrations, the required dilution rate to meet the WQO criteria for silver
and mercury were calculated to be very low (i.e. 1.5 only), which is expected
to be naturally achieved by dynamic water flow within the Harbour area.
Meanwhile, the release of contaminants would also be minimised by the use of
closed grab dredger and the dispersion of contaminants would be confined within
the construction site by silt curtains (Section 5.8). Thus, it is considered that long-term
off-site marine water quality impact would be unlikely and any local water
quality impact would be transient.
9.6.14 Nevertheless, as
subtidal fauna like fish and crab identified in the Assessment Area are mobile,
it is likely that they would avoid the dredged area and recolonise after
reclamation works. Furthermore, works will be carried out in different phase at
different locations and so there is refuge habitat available in nearby coastal
waters for the affected fauna. Thus, adverse impact due to release of
contaminant on subtidal organisms is not expected.
9.6.15 Nutrient level
(inorganic nitrogen and phosphorous) may also increase during dredging
activities. High levels of nutrients in seawater can cause rapid increases in
phytoplankton often to the point where an algal bloom occurs. An intense bloom of algae can lead to
sharp decreases in the levels of DO in the water as dead algae fall through the
water column and decompose on the bottom.
Anoxic conditions may result if DO concentration is already low or is not
replenished. This may result in
mortality to marine organisms due to oxygen deprivation. Based on the results
of water quality modelling (see water quality assessment), it is predicted that
the resultant TIN would be slightly higher than the WQO standard (i.e. < 0.4
mg/L) at several locations immediately outside the reclamation area,
implementation of proper mitigation measures would be adopted to minimise such
impact. In contrast, it is
predicted that the depth-averaged and bottom minimum DO concentration contours
in the Victoria Harbour reveal a similar pattern to that of the baseline
condition that the minimum
depth-averaged DO is greater than 4.0 mg L-1 (except water
around HKCEC which is predicted to be slightly lower than 4.0 mg/L) and the
bottom layer minimum DO is greater than
2.0 mg L-1. These results comply with the WQO for DO.
9.6.16 As discussed in
Section 9.4, the soft bottom benthic habitats are already highly hypoxic and
the associated benthic and subtidal communities in the Assessment Area are of
generally very low ecological significance, so adverse impact due to elevation
of nutrients level and DO depletion on the associated marine fauna is not
expected.
Disturbance
impact
9.6.17 During the marine
construction works, increased marine traffic and noise generated from
construction plant and dredging machines could cause disturbance impacts to the
associated waterbirds and other avifaunal species of conservation interest.
However, set against the background of intense human activities in Victoria Harbour and the CBTS, the associated
avifaunal population are considered already well adapted to human disturbance.
It is expected that displacement to the nearby waters for feeding area may
occur temporarily but adverse impact is not anticipated.
Operation phase
Indirect impact
Changes in tidal flow pattern
9.6.18 Impacts to marine
ecological resources could potentially occur if the shape of the reclamation
causes a change to the hydrodynamic regime of the harbour. Impacts of this nature could lead to
increased seabed current speeds that may cause seabed scour, thus impacting
subtidal assemblages. Conversely,
the current speeds may drop in some areas affecting flushing and water exchange
of these areas. Inadequate flushing
could lead to reduction in dissolved oxygen and increase in nutrients and
consequent impacts to marine ecological resources.
9.6.19 The hydrodynamic
modelling in previously WDII EIA report concluded that the reclamation proposed
by the Project will have minimal impact on the hydrodynamic regime of the Assessment Area and
there will be no insurmountable hydrodynamic impacts. The flow speed distributions
within the Victoria
Harbour before and after
the implementation of the Project are very similar. The reclamation will only cause
very slight change in the prevailing currents in the Assessment Area. Therefore, no ecological impact due to
changes of tidal discharges and current patterns is anticipated.
Disturbance impact
9.6.20 The Project
proposes the enhancement of recreational and heritage value of the harbour shoreline
near the ex-PCWA basin and the CBTS, by enhancing the waterfront promenade and
providing some leisure facilities including the water sport centre and harbour
educational centre. Such recreational facility would possibly cause increase in
human activities and marine traffic during the operational phase of the
Project.
9.6.21 As mentioned
previously, associated waterbirds and other bird species of conservation
interest found in Victoria
Harbour and the CBTS are
well adapted to human disturbance and so impact caused by increase in
background noise and human activities would be minimal and temporary. No
adverse impact on this associated waterbirds population and other bird species
of conservation interest would be resulted during the operation phase of the Project.
Overall impact
9.6.22 Based upon the
foregoing discussion, no adverse marine ecological impacts associated with the
Project are expected to occur during the construction and operation of the
Project. A summary of impact
evaluation is presented in Table 9.3-9.4.
Table 9.3 Evaluation
of Ecological Impacts on Marine Resources during Construction Phase.
|
Criteria
|
Construction phase
|
|
Habitat loss
|
Change in water quality
|
Disturbance impact
|
|
Impacted habitat
|
Benthic, subtidal and intertidal (artificial) habitats
|
Subtidal and intertidal habitats
|
Feeding ground in CBTS
|
|
Habitat quality
|
Very low to low
|
Very low to low
|
Low
|
|
Species
|
Only isolated and low-valued hard coral and gorgonian would be
affected
|
No rare species
|
Little Egret, Great Egret, Black-crowned Night Heron, Black Kite and
White-throated Kingfisher would be affected
|
|
Size / Abundance
|
Permanent loss of 12.7
ha seabed and subtidal habitat as well as 1 km artificial seawall habitat
Temporary loss of 10.7
ha seabed and subtidal habitat as well as 850 m artificial seawall habitat
|
Large in size
Low to moderate species abundance
|
Low species abundance
|
|
Duration
|
Persist permanently
Last throughout the construction phase
|
Temporary
|
Temporary
|
|
Reversibility
|
Irreversible for permanent reclamation area, but habitat in temporary
reclamation area would be recovered.
|
Would recover after construction phase
|
Would recover after construction phase
|
|
Magnitude
|
The magnitude of impact is considered as moderate
|
The magnitude of impact is considered as minor after implementation of
proper mitigation measures.
|
The magnitude of impact is considered as minor.
|
|
Ranking of Significance of Impacts
|
Low
|
Low
|
Low
|
|
Overall impact
|
No adverse impact
|
Table 9.4 Summary
of Evaluation of Marine Ecological Impacts during Operation Phase
|
Criteria
|
Operation phase
|
|
Change in tidal flow
|
Disturbance impact
|
|
Impacted
Habitat
|
Subtidal
and Intertidal habitat
|
Feeding
ground in CBTS
|
|
Habitat quality
|
Very low
to low
|
Low
|
|
Species
|
No rare
species
|
Little
Egret, Great Egret, Black-crowned Night Heron, Black Kite and White-throated
Kingfisher would potentially be affected
|
|
Size /
Abundance
|
Large in
size
Low to moderate
species abundance
|
Low
species abundance
|
|
Duration
|
Persist
permanently
|
Temporary
|
|
Reversibility
|
Irreversible
|
Would
recover
|
|
Magnitude
|
Very
minor
|
Very
minor
|
|
Ranking
of Significance of Impacts
|
Low
|
Low
|
|
Overall impact
|
No adverse impacts
|
9.7.1
Following EIAO-TM Annex 16 and EIAO
Guidance Note No. 3/2002, mitigation measures are discussed in this section to avoid,
minimize and compensate for identified ecological impacts.
Avoidance
9.7.2
The proposed alignment of the WDII has been
substantially revised, with consequent large reductions in potential impacts to
marine ecological resources. Under the previously proposed alignment, large
reclamation area of about 27 hectares marine habitats from coastal area of CBTS
to the HKCEC was proposed for the construction of the Trunk Road at ground
level. The revised WDII
alignment proposes alternative Trunk Road constructed in tunnel that avoids the
permanent reclamation at ex-PCWA basin and the CBTS and the consequently direct
impacts to benthic and subtidal habitats and the associated wildlife in large
part of the Project area.
Minimization
9.7.3
Recent
dive surveys revealed that coral within subtidal habitat that would be directly
affected by the proposed reclamation works was low in species diversity (only
two species) and coverage (1 – 5%), with only small colonies and common species
recorded. The subtidal habitat was therefore considered as low ecological
value. Nevertheless, those 19 coral colonies identified in recent dive survey
were small and attached to movable boulders and are practically feasible for
transplantation. As an additional measure to protect coral, it is recommended
to translocate all these potentially affected corals at ex-PCWA
Basin (Site 13) and along seawall at
North Point (Site 27) to the
nearby suitable habitats such as Junk
Bay where similar hydrographic
condition and healthy coral communities of the same species were recorded. A 10 m x 10 m coastal area at Junk Bay
is proposed as a practical and feasible recipient site (Figure 9.2). A
detailed translocation plan (including translocation methodology, monitoring of
transplanted corals, etc.) should be drafted during the detailed design stage
of the Project. The coral translocation exercise should be conducted before the
commencement of construction phase of the Project. The translocation
methodology, monitoring proposal and, the ecologist involved in this
translocation exercise should be approved by AFCD prior to commencement of this
exercise. Detailed requirements
on coral translocation are discussed in the EM&A Manual.
9.7.4
During
dredging and filling operations, a number of mitigation measures to control
water quality would be adopted to confine sediment plume within reclamation area and protect marine fauna in proximity to the
reclamation. The mitigation measures include the following:
·
Installation of silt curtains during dredging
activities.
·
Use of tightly-closed grab dredger.
·
Reduction of dredging rate.
·
Control of grab descending speed.
·
Construction
of leading edges of seawall in the early stages of the reclamation works.
·
Adoption of multiple-phase construction schedule.
9.7.5
These
mitigation measures are expected to result in no substantial changes in water
quality, and only minimal ecological effects on marine environment and
associated wildlife would result.
9.7.6
To minimize potential disturbance impacts on the
foraging ardeid population in the CBTS, particularly in the area near the A
King Shipyard, appropriate mitigation measures shall be adopted particularly
during the construction phase. The following measures are recommended:
·
Use of Quiet Mechanical Plant during the construction
phase should be adopted wherever possible.
·
Adoption of multiple-phase construction schedule.
·
General measures to reduce noise generated during the construction
phase (see noise impact assessment) should be effectively implemented.
9.7.7
Vertical
seawalls should be placed around the dredging areas and construction boundaries
within the area of the CBTS to screen adjacent feeding ground from construction
phase activities, reduce noise disturbance to the associated seabirds and also
to restrict access to this habitat adjacent to works areas by ship traffic.
Other Measures
9.7.8
As
described previously, loss of artificial seawall habitat due to temporary
reclamation would be reinstated after construction works and similar
assemblages of flora and fauna would be re-colonized naturally over time. For
the loss of artificial intertidal habitat, it would be recovered by the
construction of about 1 km
vertical wave absorbing seawall along the coastlines of the newly reclamation
land around the HKCEC and at the North Point. The new seawalls are expected to
provide large area of hard substrata for settlement and recruitment of
intertidal and subtidal assemblages similar to those previously recorded from
existing habitats.
9.8.1
With
the effective implementation of mitigation measures proposed in Section 9.7,
residual effects on marine ecology are expected to be very minor. The only
identified residual impact would be the
loss of approximately 12.7 hectares soft bottom benthic and subtidal
habitats of generally very low ecological significance due to permanent
reclamation works. Overall, no
adverse residual impacts on marine ecology resulting from the Project are
expected.
9.9.1
There
are several planned or concurrent works for the other projects conducted in and
within the vicinity of the Assessment Area, including the following:
·
Central
Reclamation Phase III (CRIII) Project
·
Hong Kong Convention and Exhibition Centre (HKCEC) Atrium Link
Extension Project
·
Project
for the Western Cross
Harbour Main
from Wan Chai to Tsim Sha Tsui
·
Western
Cross Submarine Gas Pipelines Project
·
Kai
Tak Development (KTD) Project
9.9.2
As
dredging and filling activities are also included in the above projects, except
the HKCEC Project, the most concerned cumulative impact would be the cumulative
effect on the deterioration of water quality in the Victoria Harbour.
9.9.3
For
all the concurrent projects listed above, water quality modeling (see water
quality assessment) predicted that the dredging and reclamation works
undertaken for these concurrent projects would result in elevation of SS level
of more than 30 % of ambient level at several locations immediately outside the
dredged area under the worse case scenario. With the implementation of proper
mitigation measure mentioned and recommended in the water quality assessment,
cumulative impact on change of water quality in the Assessment Area could be
effectively minimized and is expected to be acceptable. Cumulative impact of
change of water quality on far-field ecological sensitive receivers including
coral areas at Green Island, Little Green Island and Junk Bay
is predicted to be complied with the assessment criteria for corals set in this
assessment and therefore no adverse cumulative impact on these far-field
ecological sensitive receivers is expected to occur.
9.9.4
The
other potential cumulative impact would be the cumulative disturbance impact to
the marine habitat and the associate wildlife arising from the increased level
of human activities and noise from construction and operation phases. Regarding
the existing high level of disturbance in the Assessment Area, this cumulative
impact is anticipated to be temporary and minimal. No adverse cumulative impact
on the marine habitats and the associated wildlife is expected.
9.10.1 As all the 19 coral
colonies found in recent dive surveys were identified as feasible for
transplantation, it is
recommended to translocate all these coral colonies to the nearby suitable
habitats such as Junk Bay where similar hydrographic condition and healthy
coral communities of the same species were recorded. A detailed translocation
methodology (including baseline survey and monitoring of transplanted corals)
should be drafted during the detailed design stage of the Project. Pre-translocation
survey on coral at the ex-PWCA Basin (Site 13) and along seawall at North Point (Site
27) would
be focused on identifying and mapping of coral colonies that would be directly
affected by the proposed reclamation works and recording the condition of these
coral colonies (e.g. health status of coral colony). The detailed methodology, monitoring proposal and
ecologist involved in coral translocation should be approved by AFCD prior to
commencement of this translocation exercises. It is also important to
ensure that the proposed relocation of the coral colonies will not affect any
private/public marine uses / rights at the recipient site.
9.10.2
It is recommended to implement monitoring of the
transplanted corals after translocation. The health status of each transplanted
coral colony should be carefully recorded.
For hard corals, this should include information on surface area with
partial mortality and blanched / bleached area. For gorgonian coral, the
percentage of branches affected by partial mortality and secretion of mucus
should be recorded. Details of monitoring requirements are presented in the
EM&A manual.
9.11.2 Direct and indirect
ecological impacts arising from the Project during construction phase and
operation phase were identified and evaluated. The Project will result in the
permanent loss of approximately 12.7 hectares of soft bottom benthic and
subtidal habitats. Considering that the benthic, intertidal and subtidal
habitats within affected area are of very low ecological value, and as direct
impacts on some small and isolated coral colonies attached to movable boulders
would be avoided by translocation, no adverse direct ecological impact is
expected.
9.11.3 Indirect disturbance
impact on the associated waterbirds and other avifaunal species of conservation
interest in the CBTS and Victoria
Harbour was expected to
occur during the construction and operation phases of the Project. Considering
the existing background of intense human activities in these areas, the
affected wildlife are considered already well adapted to human disturbance and
therefore no adverse indirect impact is expected to occur.
9.11.4 Other impacts
arsing from the Project would be temporary and minimised with implementation of
proper mitigation measures. Overall, no adverse ecological impacts on marine
resources are anticipated.
9.12
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