This section of the EIA report assesses the
potential ecological impact associated with the proposed 132 kV supply circuit
from Pui O via Chi Ma Wan Peninsula via sea crossing towards Cheung Chau. Baseline ecological conditions in the Study
Area have been established based on a literature review and field surveys. Potential sources of impacts have been
identified and assessed and, where appropriate, requirements for mitigation and
monitoring recommended.
A number of international and local
regulations, legislation and guidelines provide the framework for the
protection of species and habitats of ecological importance. Those related to the Project are:
·
Country Parks Ordinance (Cap 208);
·
Forests and Countryside Ordinance (Cap 96) and its subsidiary legislation, Forestry Regulations;
·
Wild Animals Protection Ordinance (Cap 170);
·
Town Planning Ordinance (Cap 131);
·
Hong Kong Planning Standards and Guidelines Chapter
10 (HKPSG);
·
Technical Memorandum on Environmental Impact
Assessment Process
(EIA-TM) for the Environmental Impact
Assessment Ordinance; and
·
United Nations Convention on Biodiversity (1992).
The Country
Parks Ordinance provides for the designation and management of Country
Parks and Special Areas. Country Parks
are designated for the purpose of nature conservation, countryside recreation
and outdoor education. Special Areas
are created mainly for the purpose of nature conservation.
The Forests
and Countryside Ordinance prohibits felling, cutting, burning or destroying
of trees and growing plants in forests and plantations on Government land. Related subsidiary Regulations prohibit the
picking, felling or possession of listed rare and protected plant species. The list of protected species in Hong Kong
which comes under the Forestry Regulations was last amended on 11 June 1993
under the Forestry (Amendment) Regulation
1993 made under Section 3 of the Forests and Countryside Ordinance.
Under the Wild
Animals Protection Ordinance, designated wild animals are protected from
being hunted, whilst their nests and eggs are protected from destruction and
removal. All birds and most mammals are
protected under this Ordinance. The
Second Schedule of the Ordinance that lists all the animals protected was last
revised in June 1992. All cetaceans are
protected under this Ordinance.
The recently amended Town Planning Ordinance provides for the designation of coastal
protection areas, Sites of Special Scientific Interest (SSSIs), Green Belt or
other specified uses that promote conservation or protection of the
environment, e.g. conservation areas.
The authority responsible for administering the Town Planning Ordinance is the Town Planning Board.
Chapter 10 of the HKPSG covers planning
considerations relevant to conservation.
This chapter details the principles of conservation, the conservation of
natural landscape and habitats, historic buildings, archaeological sites and
other antiquities. It also addresses
the issue of enforcement. The
appendices list the legislation and administrative controls for conservation,
other conservation related measures in Hong Kong and Government departments
involved in conservation.
Annex 16 of the EIA-TM sets out the general
approach and methodology for assessments of ecological impacts arising from a
project or proposal, to allow a complete and objective identification,
prediction and evaluation of the potential ecological impacts. Annex
8 recommends the criteria that can be used for evaluating ecological
impacts.
The Peoples' Republic of China (PRC) is a
Contracting Party to the United Nations
Convention on Biological Diversity of 1992. The Convention requires signatories to make active efforts to
protect and manage their biodiversity resources. The Government of the Hong
Kong Special Administrative Region has stated that it will be 'committed to
meeting the environmental objectives' of the Convention.
The establishment of the baseline terrestrial
ecological profile of the Study Area (covering all areas within 500m of the
proposed works area) and assessment of potential impacts are based on field
surveys including habitat/vegetation and wildlife, as well as a review of the
available literature. A literature
review of the terrestrial ecological conditions within the Study Area was
conducted including the Ecological Study of Freshwater Wetland in Hong Kong
(Dudgeon and Chan, 1996). Consultations with local ecologists were
also undertaken, where appropriate.
Habitat and ecological communities within the Study Area were mapped
with reference to the Vegetation Map prepared by World Wide Fund for Nature
Hong Kong (1993).
Broad scoping field surveys were then
undertaken to supplement and field-check the data collected through the
baseline/literature review process.
Areas of ecological interest that would be directly or indirectly
affected by the proposed electric cable circuit were then surveyed in more
detail.
All the field
data wereere collected between October 2000 and
September 2001, covering the transitional period of wet and dry seasons, as
well as the wet and dry season. The
ecological surveys covered habitat/vegetation, mammals, avifauna, amphibian/reptile,
invertebrates and stream fauna, as well as applicable night surveys, and the
methodologies used are presented below.
Each representative habitat type was surveyed
on foot. All plant species encountered
were identified and recorded to species level, whenever possible, and the
relative abundance of the plant species was also recorded. The dominant flora and fauna of each
habitat/land-use type were also identified, with subsequent further habitat and
vegetation verifications undertaken.
Surveys were undertaken on 20, 22 and 27 November 2000 and 6 September
2001. Species names and local
conservation status of all native plant species & all naturalized exotic
species followed Corlett et al.
(2000), while the different names used in the Checklist of Hong Kong Plants
(Hong Kong Herbarium, 1993) were listed in brackets as well for
completeness. Names of cultivated
plants follow the Checklist of Hong Kong Plants (Hong Kong Herbarium, 1993).
Signs or other evidence of mammal presence were
noted in the field by active searching in potential mammal habitats. Surveys were undertaken on 28 October and 11
November 2000.
The bird surveys were undertaken in all major
habitat types within the Study Area quantitatively (using the point count
method) and qualitatively. For the
point count method, a total of twenty minutes was spent counting birds at each
point (Figure 6.1). All birds seen or heard within 30 m of each
point count location were counted and identified to species level where
possible. All the bird species seen or
heard within the Study Area were also recorded. Signs of breeding (e.g. nests, recently fledged juveniles) and
the habitat utilization of the different species were also recorded. Surveys were undertaken on 25 October, 27
November and 20 December 2000.
Sampling techniques involving direct
observation and active searching for reptiles in potential shelter sites/hiding
places and, for amphibians in potential habitats, were employed. Surveys were undertaken on 28 October and 11
November 2000.
The abundance of adult butterfly, dragonfly and
damselfly fauna were investigated by direct observation and active searching,
in all major habitat types within the Study Area. Any butterfly, dragonfly
and damselfly seen were identified and counted during the survey. Butterfly, dragonfly and damselfly were
netted where required for identification.
Identification of Odonates followed Wilson (1997) and identification of
butterflies followed Walthew (1997).
The weather conditions on both days were suitable for the survey of
aerial insects (sunny, warm and light wind conditions) (New, 1998). Surveys were undertaken during the active
day time of butterfly, dragonfly and damselfly (between 1000 and 1600
hrs). Surveys were undertaken on 27
October and 1 November 2000.
Aquatic fauna were investigated through direct
observation and active searching, as well as using a hand net. The freshwater fish survey used hook and
line (in main stream) and hand-nets (mainly in marshes and near
estuaries). Surveys were undertaken on
27 & 28 October and 11 November 2000.
A night survey (11 October 2000) was undertaken
in the Pui O areas mainly focusing on nocturnal wildlife including mammals and
amphibians.
The potential ecological impacts due to the
installation of 132 kV circuit were assessed following EIA-TM Annex 16 guidelines and the impacts
evaluated based on the criteria in EIA-TM
Annex 8.
Lantau South Country Park encompasses a wide
range of land habitats, from grassland to some of the finest forest in Hong
Kong. The Park has a long coastline,
particularly in Chi Ma Wan Peninsula, supporting a wide range of fauna such as
insects, reptiles and a variety of birds.
Parts of the Lantau South Country Park are located within the Study
Area, but outside the Works Area (Figures
6.2 & 6.3), comprising generally tall shrubland or forest.
Pui O Marsh and Taro Bed were identified as
important wetlands by Dudgeon and Chan (1996) and comprise part of an
extensive, low-lying wetland. The Taro
Bed was reported as containing a number of rare macroinvertebrates, including Macrodiplax larvae, hydrophilid beetles
and Sphaeromias sp., and several
frogs (ie Polypedates megacephalus and
the Marbled Pygmy Frog Microhyla pulchra). The area is distinctive because of the
presence of a resident population of water buffaloes, one of the few remaining
areas where they still occur in Hong Kong.
The field surveys identified that the Study
Area is covered by a variety of habitats including forest, tall shrubland,
shrubland and grassland mixture, wetland, abandoned farmland, farmland, rocky
shore, sandy beach, backshore shrubland, mangrove, brackish mudflat,
plantation, wasteland, village area and stream. Wetland and village area were the dominant habitat type in the
flat land area whereas the hillsides were dominated by tall shrubland and
forest. The Study Area and the
locations of various habitat types are shown on Figures 6.2 and 6.3, and
photographic records of representative habitat types are shown on Figure 6.4. Species lists of flora and fauna are given in Appendix G.
Forest found within the
Study Area included secondary and fung-shui
forests. The forests are continuous
with a height ranging from 4 m to 15 m, and diameter at breast height (dbh)
ranging from 10 cm to 70 cm. The forests
showed considerable variation in species composition and structure with a total
of 62 species of trees and 113 plant species recorded. Since secondary and fung-shui forests are physically continuous and showed a continuum
in composition, they are regarded as a single habitat type.
The secondary forest is the
predominant forest habitat type within the Study Area with a height ranging
from 4 m to 10 m. The plant diversity
is co-dominated by Sapium discolor, Mallotus paniculatus, Microcos paniculata, and Sterculia lanceolata. The introduced species Casuarina equisetifolia and Tristania
conferta are locally abundant and apparently planted on the hillside
south-east of Chi Ma Wan Road, but the native secondary woodland species still
dominate.
There are five patches of fung-shui forest, one close to the
proposed Pui O portal, two behind Ham Tin and two behind Pui O Lo Wai Tsuen and
Pui O San Wai Tsuen, found in the Study Area.
The fung-shui forest is
relatively old growth with a height rainging from
6 m to 15 m and has not been disturbed for 20 to 50 years. The plant diversity is co-dominated by Aquilaria sinensis, Bischofia javanica, Machilus
chekiangensis, Ailanthus fordii,
and Sterculia lanceolata.
Eight plant species of
conservation importance were found including six rare to very rare species, Ailanthus fordii, Malaisia scandens, Urceola
micrantha (Parabarium micranthum),
Uncaria hirsuta, Uvaria calamistrata, and Xenostegia
tridentata (Merremia hastata) and
two locally common but protected species in China and Guangdong (Aquilaria sinensis and Gmelina chinensis). Although Dalbergia balansae is also listed as
“rare” in Corlett et al. (2000), it
has been found to be locally very abundant in a number of places in Hong Kong
and was widely planted in Hong Kong, and therefore should be ranked in the
“restricted” category (S. C. Ng pers. comm.).
Tall shrubland is defined as woody
vegetation with a modal height of 1.5 m to 4 m and is a transitional stage in ecological
succession between shrubland and forest. This habitat type is similar to shrubland in
species composition but tends to be dominated by woody species and
climbers. A total of 127 plant
species were recorded in this habitat within the Study Area which is dominated
by Litsea
rotundifolia var. oblongifolia, Rhodomyrtus tomentosa, Cratoxylum
cochinchinense, Eurya nitida (E. japonica in HK Checklist) and Strophanthus divaricatus. The floristic diversity is considered high
and the structural diversity is considered moderate to high. Five plant species
of conservation interest were found including one rare species, Cyclobalanopsis glauca, and four
locally common but protected species in Hong Kong (Pitcher Plant Nepenthes mirabilis and Cleisostoma simondii (C. teres)), Guangdong, (Gmelina chinensis), and China (Artocarpus hypargyreus), respectively.
Shrubland and grassland mixture is defined here
as vegetation dominated by herbaceous and woody plant species with a modal
height of less than 1.5 m. This habitat
is mainly found at higher altitude and in small patches behind rocky shores
within the Study Area. A total of 56
plant species were recorded in the shrubland and grassland mixture within the
Study Area which is dominated by Litsea rotundifolia var. oblongifolia, Rhodomyrtus
tomentosa, Dicranopteris linearis, Eulalia quadrinervis, and Ischaemum barbatum. The co-dominance of Dicranopteris linearis
suggested that the habitat had been frequently disturbed by hill fires. Neither rare nor protected plants were
recorded during the survey. This
habitat is relatively high in floristic diversity but moderate in structural
diversity.
Wetland refers to the waterlogged and
seasonally or permanently submerged flatland.
This habitat was found between the Pui O villages and the Pui O beach
including the Pui O Marsh and Taro Bed.
It is a semi-natural habitat originated from paddy fields abandoned
approximately 20 years ago. The height
of the vegetation is maintained below 1 m due to the grazing effect of Water
Buffalo. There was a total of 52
species recorded in this habitat which is high compared with other wetlands in
Hong Kong. The major dominant species
found in the wetland included Bacopa
monnieri, Sacciolepis indica, Isachne globosa, Rotala indica, and Chrysopogon
aciculatus. This habitat is
relatively high in floristic diversity but low in structural diversity. There were four rare to very rare species
recorded, Azolla imbricata, Ceratopteris
thalictroides, Marsilea quadrifolia and
Salvinia natans, which are mostly past paddy field weeds. The habitat itself, however, is of high
quality and rare because of its size and floristic diversity and the high
abundance of the locally rare Marsilea
quadrifolia and Salvinia natans,
both of which are locally co-dominant at the center of the wetland. Although Fimbristylis
acuminata was listed as “rare” in Corlett et al. (2000), it is locally abundant in a number of wetland sites
in Hong Kong and should be ranked in the “restricted” category (S.C. Ng, pers.
comm.).
The abandoned farmland was found beside the
wetland habitat between Pui O Lo Wai Tsuen/ San Wai Tsuen and the Pui O
beach. This habitat is similar to
wetland in appearance but does not have permanently waterlogged soil and is
rarely submerged. Similar to the
wetland habitat, the height of the vegetation is maintained below 1 m due to
the grazing effect of Water Buffalo, although isolated trees or shrubs of Sapium sebiferum and Lantana camara could be found on the
mud-bund. There was a total of 47
species recorded in this habitat dominated by Chrysopogon aciculatus, Cynodon
dactylon, Cyperus rotundus and Rotala indica. This habitat is relatively moderate in floristic diversity but
low in structural diversity. Neither
rare nor protected plants were recorded during the survey.
There were only two small patches of active
farmland found beside the wetland at Pui O in the Study Area. Although the vegetation cover was greater
than 60%, only 16 species were recorded and the species composition was
dominated by introduced crop plants including Ipomoea batatas, Lactuca sativa, Clausena lansium,
and Dimocarpus longan. Both the floristic and structural diversity
of the habitat was considered to be low.
Neither rare nor protected plants were recorded during the survey.
The vegetation cover is extremely sparse at the
sea side, which is dominated by barren bedrock and boulders, whereas the back
is dominated by typical backshore vegetation and is continuous to shrubland or
secondary forest behind. There was a
total of 56 species recorded in this habitat dominated by Severinia buxifolia (Atalantia buxifolia), Heteropogon contortus, Sageretia
thea, and Litsea rotundifolia var.
oblongifolia. This habitat is
relatively moderate in floristic diversity but low in structural diversity due
to the sparse vegetative cover. One
locally rare species, Rhamnus
leptophyllus, was found in this habitat.
It had been confused, in the past, with R. brachypoda, a restricted species in HK. Although Berchemia
lineata and Trachelospermum
jasminoides were listed as “rare” in Corlett et al. (2000), they are more abundant and should be ranked in the
“restricted” category (S.C. Ng, pers. comm.).
This habitat type is represented by the beaches
at Pui O (gazetted bathing beach) and Tai Long Wan. Such habitat is characterized by mobile sandy substratum with
very sparse to no vegetation cover at the front, whereas the back is dominated
by creeper and stoloniferous plants and is continuous with backshore
shrubland. There was a total of 32
species recorded in this habitat dominated by Ipomoea pes-caprae (I. brasiliensis), Vitex rotundifolia, Clerodendrum
inerme, Wedelia biflora and Canavalia rosea (C. maritima). This habitat is relatively moderate in
floristic diversity but low in structural diversity. Neither rare nor protected plants were recorded during the
survey.
Backshore shrubland refer to the dense tall
shrubland found behind the sandy beach at Pui O and Tai Long Wan beaches. There were a total of 44 species recorded in
this habitat dominated by Caesalpinia bonduc, Pandanus tectorius, and Casuarina equisetifolia, which were
probably planted previously. This habitat has relatively moderate
to low in floristic diversity and moderate in structural diversity. Except rare plant
species, Agave vivipara, neither
rare nor protected plants were recorded during the survey. Although the rare Agave vivipara was recorded in this
habitat, it is an introduced and naturalized species and, therefore, without
conservation importance.
Mangrove is defined as woody vegetation
dominated by salt-tolerant species found in the intertidal area. Mangrove was found on both sides of the
estuary between Ham Tin and Pui O beach.
There was a total of 28 species recorded in this habitat dominated by Excoecaria agallocha, with other
mangrove species (Kandelia candel and
Aegiceras corniculatum) occurring in
smaller numbers. This habitat is
relatively moderate in floristic diversity and moderate to high in structural
diversity as the height of vegetation is comparable to tall shrubland. Neither rare nor protected plants were
recorded during the survey. The
mangrove trees recorded were in reasonably good condition with heights ranging
from 2 m to 3 m.
Brackish mudflat refers to the mudflat found on
the estuary between Ham Tin Village and Pui O beach. There was a total of 8 species recorded in this habitat which was
largely dominated by Zoysia sinica
and Cyperus stoloniferus. Both the floristic and structural diversity
were considered as low. Neither rare
nor protected plants were recorded during the survey.
Plantation included government plantation as
well as all orchards with a usual height ranging between 3 m and 6 m. Although this habitat is under strong human
influence, it has more than 80% vegetation cover composed mainly of introduced
landscape/crop tree or plants. There
was a total of 30 species recorded in this habitat dominated by Acacia confusa,
Celtis tetrandra ssp. sinensis (C. sinensis), Clausena lansium, Dimocarpus longan,
and Litchi chinensis. In addition some weedy or secondary forest
species were recorded. This
habitat was relatively moderate in floristic diversity and high in structural
diversity. Neither rare nor protected
plants were recorded during the survey.
Wasteland refers to unused area filled with
mineral debris (sand, soil, and gravel) and/ or refuse. This habitat was found beside the wetland
and Ham Tin village. The vegetation
cover was more than 60% and the species composition was similar to that of
village areas with a total of 32 species and dominated by weedy species
including Cynodon
dactylon, Mikania micrantha, Ipomoea
cairica, Eupatorium catarium (Praxelis clematidea), and Sageretia thea. This habitat is relatively moderate in
floristic diversity and simple in structural diversity.
Village area included all village houses,
concrete roads, and buildings. The
vegetation was sparse in this habitat with more than 70% of the area covered in
concrete. There was a total of 50
species recorded in this habitat dominated by Acacia confusa, Mikania micrantha, Ipomoea cairica,
Lantana camara, and Eupatorium
catarium (Praxelis clematidea).
More than half of the species recorded are either exotic, introduced, or
cultivated/ornamental species. This
habitat is relatively moderate in species diversity but low in structural
diversity. Neither rare nor protected
plants were recorded during the survey.
There are four permanent streams (always
containing water), S1, S2, S3 and S4, recorded within the Study Area. Streams S1 and S2 are mid-sized streams,
while S3 and S4 are smaller. The upper
section of stream S1 is natural with large boulders on the stream bed, while
the middle section has been channelized but still with a natural rocky
bottom. The lower section is partially
channelized and stream sediments consisted of fine-grains with mid to large
sized boulders. The upper and middle
courses were open and the riparian vegetation comprised mostly trees. The lower course, however, was semi-open and
the riparian vegetation comprised mostly grasses and shrubs.
The middle section of stream S2 has been
channelized and re-constructed by ‘boulder blocks’. The lower course of S2 is estuary connected to the brackish
mudflat.
The upper and middle courses of S3 are less
disturbed and shaded by trees and shrubs.
The lower course of S3, similar to S2, is estuary connected to brackish
mudflat. There were about 10
residential buildings located alongside the lower stream course, and the stream
appear to be polluted to a certain degree, evidenced by the black colour
substratum in the estuary.
S4 is a small stream with limited freshwater
flow located inside forest. The stream
base sediments consisted of fine-grains with many overlying boulders.
Except three bats (two unidentified and one
Japanese Pipistrelle Pipistrellus abramus),
no signs of mammal existence (such as trails, burrows) were observed or noted
in the Study Area during the surveys.
However, many local villagers reported the presence of Masked Palm Civet
(Paguma larvata), Barking Deer (Muntiacus reevesi) and Wild Boar (Sus scrofa). Since the Study Area has diverse habitats and lies adjacent to
Lantau South Country Park, these wide-ranging animals may occasionally visit
part of the Study Area that are less affected by human disturbance.
A total of 47 bird species were recorded within
the Study Area during the surveys, most of the species were recorded in Pui
O. The Majority of the recorded species
are common and typical in Hong Kong, such as Chinese Bulbul Pycnonotus sinensis, Common Magpie Pica pica and White Wagtail Motacilla alba.
The Greater Coucal Centropus sinensis, Pacific Reef Egret Egretta
sacra, Black Kite Milvus lineatus,
Great Crested Grebe Podiceps cristatus and
Red-billed Starling Sturnus sericeus
are commonly found in Hong Kong, however, they are regarded as species of conservation
concern. Greater Coucal Centropus sinensis, Pacific Reef Egret Egretta sacra, Black Kite Milvus lineatus and Great Crested Grebe Podiceps cristatus are listed as Class
II protected wildlife of national importance in China (MacKinnon and
Phillipps, 2000). Greater Coucal
Centropus sinensis and Pacific Reef Egret Egretta sacra are also listed as vulnerable and rare in China Red
Data Book. Red-billed Starling Sturnus sericeus is identified as a
globally threatened species (Collar et
al., 1994). No breeding activities
were recorded during the survey.
There were only four amphibian species recorded
during the surveys including Günther’s Frog Rana
guentheri, Paddy Frog Rana
limnocharis, Three-striped Grass Frog
Rana macrodactyla and Chinese Bullfrog
Rana rugulosa. Most of the species were found in Pui O Marsh and Taro
Bed. Only Chinese Bullfrog Rana rugulosa is protected in China
(Hua and En, 1993) and considered as uncommon, and the other species are all
common and widespread in Hong Kong. Sixty years ago the Chinese Bullfrog was
considered as the most common species locally but has since become less common
(Romer, 1979; Karsen et al, 1986).
In the case of reptiles, five common species,
Changeable Lizard Calotes versicolor,
Long-tailed Skink Mabuya longicaudata,
Common Rat Snake Ptyas mucosus,
Checkered Keelback Xenochrophis piscator
and Red-eared Slider Trachemys scripta
elegans were observed during the surveys.
Except the Common Rat Snake Ptyas
mucosus listed as endangered species in China Red Data Book, neither rare,
endangered, nor endemic species were found.
Twenty-eight species of butterflies were
reported from Pui O in surveys conducted in 1976 (Bascombe, unpubl. data). Most were either very common or common in
Hong Kong, except four uncommon species, namely Banana Skipper Erionota torus, Bush Hopper Ampittia dioscorides, Quaker Neopithecops zalmora and Hong Kong
Lacewing Cethosia biblis. The habitat uses, food plants and global
distributions of these species are shown in Appendix G Table G-19. None
of the recorded butterfly species is protected in Hong Kong or China. Five species of dragonflies have been
reported from Pui O (Wilson 1997) where Neurothemis
tullia was present in large numbers in Pui O Marsh. This species is usually found in wet
abandoned cultivated lands (Wilson 1995).
Of the five recorded species all are common and widespread except Tramea transmarina (Wilson 1997). None of the recorded dragonfly species is
protected in Hong Kong or in China, and none is endemic to Hong Kong (Wilson
1997). Pui O is the site of the only
known Hong Kong record of Tramea
transmarina, a migratory Southeast Asian dragonfly (Wilson 1997, Dudgeon
and Chan 1996). The specimen was
recorded after a typhoon in June 1991 and was, therefore, considered a
potential vagrant rather than likely to be indicative of a resident population
(Wilson 1997).
Thirty-four species of butterfly, such as
Angled Castor Ariadne ariadne, Dark
Veined Tiger Danaus genutia, Common
Mormon Papilio polytes and Common Grass Yellow Eurema hecabe, were recorded during the surveys. Except five uncommon species recorded,
including Purple Sapphire Heliophorus
epicles, Yellow Pansy Junonia hierta,
Lemon Pansy Junonia lemonias, Blue
Pansy Junonia orithya and Yellow
Orange Tip Ixias pyrene, all the
recorded species are either very common or common in Hong Kong. None of the butterfly species recorded in
the Study Area is protected in Hong Kong or China. Lemon Pansy, Blue Pansy and Yellow Orange Tip are dependent on
woodland habitats. The high diversity
of butterflies reflects the diverse and undisturbed nature of the Study
Area.
A total of 17 species of dragonfly were
recorded within the Study Area including Wandering Glider Pantala flavescens, Neurothemis tullia and Orthetrum sabina. All
recorded species are common and widespread in Hong Kong, and none are endemic
to Hong Kong (Wilson 1997) or protected in Hong Kong or China. Several species of dragonfly including Agriocnemis femina, Anax parthenope and Orthetrum
sabina were observed laying eggs in wetland and stream areas during the
surveys.
Two ecological important wetland sites in Pui
O, namely Pui O Marsh and Pui O Taro Bed, were identified by Dudgeon and Chan
in a Hong Kong-wide study of freshwater wetlands (1996). A very diverse aquatic invertebrates was
recorded in the two sites, with leeches reported as an important part of the
invertebrate fauna in the taro bed (Dudgeon and Chan 1996; Dudgeon & Chan
1994). Rare invertebrates recorded in
abandoned cultivated lands in Pui O included hydrophilid beetles (Scavenging
Water Beetles) and Sphaeromias sp.
(Ceratopogonidae: Biting Midges).
A list of fish species has been reported from
the Chi Ma Wan Peninsula (notably around Shap Long) by Chong and Dudgeon (1992)
included, eels Anguilla japonica and Anguilla marmorata, the brackish-water
ribbon eel Pisoodonophis boro, the
Rice Fish Oryzias curvinotus, the
brackish-water mullet Osteomugil
ophuyseni, the brackish-water glassfish Ambassis
gymnocephalus, the sea perch Lateolabrax
japonicus, brackish-water sillago Sillago
sihama, Mangrove Snapper Lutjanus
argentimaculatus, Russell’s Snapper Lutjanus
russellii, tigerfish Terapon jarbua,
rabbitfish Siganus fuscescens,
sleepers Eleotris acanthopoma, Eleotris oxycephala, Butis butis, gobies Tridentiger trigonocephalus, Luciogobius
guttatus, Bathygobius fuscus, Glossogobius biocellatus, Glossogobius giuris, Glossogobius olivaceus, Stimatogobius javanicus, Ctenogobius giurinus, and Acanthogobius flavimanus. The torrent loach Liniparhomaloptera disparis and freshwater goby Ctenogobius duospilus were recorded from
Pui O but it should be noted that Pui O was not one of the major study sites
(Chong and Dudgeon, 1992). Dudgeon and
Chan (1996) also reported that Paradise Fish Macropodus opercularis were found in Pui O.
Seven species of freshwater aquatic
invertebrates including Mitten crab Eriocheir
japonicus, Palamonid shrimp Macrobrachium
sp. and Buffalo Leech Poecilobdella
assimilis, were recorded within the Study Area during the field
surveys. The majority of these
invertebrates were crustacean, and only one species of annelid (Buffalo Leech)
was recorded. None of the species found
was protected in Hong Kong. Two species
of Atyid shrimp Caridina apodosis and
Caridina serrata, were recorded during the survey, which have been reported
as having a limited distribution in the south China region. (Cai & Ng
1999). In Hong Kong, there are three
species of this genus reported, namely, Caridina
cantonensis, C. apodosis and C. serrata, which are usually found in mountain streams with clean water. In a recent review on the genus Caridina, samples of the genus from
different regions in East Asia were examined. Caridina serrata is only recorded on Hong Kong Island and Lantau
Island, and it was suggested that this endemic species should be regarded as
endangered, due to its limited distribution and the degree of urbanization of
Hong Kong Island. Caridina serrata is a tiny animal with a carapace length usually shorter
than 5 mm, and the body length around 2 cm.
Twenty species of fish including Oreochromis niloticus, Gambusia affinis,
Capoeta semifasciolata and Macropodus
opercularis, were recorded within the Study Area. Since the lower courses of the freshwater streams connected to
the Pui O estuary, some brackish water fish species such as Lateolabrax japonicus, Mugil cephalus, and
Sparus berda were also recorded. Except
Parazacco spilurus, listed as vulnerable in China Red Data Book, neither
rare, endangered, nor endemic species were recorded. Parazacco spilurus
classified as vulnerable in the China Red Data Book (Yue and Chen, 1998) due to
its scientific value and restricted range on a global scale, but it is
widespread and common in Hong Kong. Macropodus opercularis and Capoeta semifasciolata are widespread
and common lowland species in Hong Kong, however, the increasing disappearance
of lowland wetlands and streams due to habitat destruction and pollution may
affect their population in the future.
The ecological importance of the habitats
identified has been evaluated against the criteria recommended in Annex 8 of the EIA-TM. This evaluation is presented below.
Table 6-1 Ecological Value
of Forest in the Study Area
|
Criteria |
Forest |
|
Naturalness |
High.
Natural secondary forest to relatively old-growth fung-shui woodland
that had not been disturbed for 20 to 50 yrs. |
|
Size |
The total size of this habitat is
approximately 76.2 ha. |
|
Diversity |
High in terms of floristic diversity &
structural diversity. Forest with
height ranging from 4 to 15m providing a wide range of microhabitat for
wildlife. |
|
Rarity |
Eight species of plant with conservation
importance were found including six rare to very rare species (Ailanthus
fordii, Malaisia scandens, Urceola micrantha (Parabarium micranthum), Uncaria hirsuta, Uvaria calamistrata, and Xenostegia
tridentata (Merremia hastata))
and two locally common but protected species in China and Guangdong (Aquilaria sinensis and Gmelina chinensis). Although
Dalbergia balansae is also listed
as “rare” in Corlett et al (2000), it has been found to be locally very
abundant in a number of places in Hong Kong and was widely planted in Hong
Kong, and therefore should be in the “restricted” category (S. C. Ng pers.
comm.). Five uncommon butterfly
species were also recorded including Purple Sapphire Heliophorus epicles, Yellow Pansy Junonia hierta, Lemon Pansy Junonia
lemonias, Blue Pansy Junonia
orithya and Yellow Orange Tip Ixias
pyrene. |
|
Re-creatability |
The habitat characteristics are difficult to
recreate. |
|
Fragmentation |
Not fragmented. |
|
Ecological
Linkage |
High.
Continuous with surrounding forest and tall shrubland. |
|
Potential
value |
Ecological potential is high if the forest
remains undisturbed. |
|
Nursery/Breeding
Ground |
Not reported, but it is likely to be utilised
by localised species of birds and mammals. |
|
Age |
Ranging from approximately 30 years for
secondary forest to 100 years for fung-shui forest behind villages at Pui O. |
|
Abundance/Richness
of Wildlife |
The abundance and diversity of birds and
butterflies recorded were moderate and high respectively. |
|
Overall Ecological Value |
High |
Table 6-2 Ecological Value
of Tall Shrubland in Study Area
|
Criteria |
Tall Shrubland |
|
Naturalness |
Moderate to High. Natural secondary tall shrubland that had not been disturbed
for 10 to 20 years. |
|
Size |
The total size of this habitat is
approximately 125.9 ha. |
|
Diversity |
High in terms of floristic diversity but only
moderate to high in structural diversity. 127 plant species was recorded
within the habitat. |
|
Rarity |
Five species of plant with conservation
interest were found including one rare species (Cyclobalanopsis glauca)
and four locally common but protected species in Hong Kong, (Nepenthes mirabilis, Cleisostoma simondii (C. teres)), Guangdong (Gmelina chinensis), and China (Artocarpus hypargyreus), respectively. Common Rat Snake Ptyas mucosus and Black Kite Milvus lineatus were recorded
near Shap Long Kau Tsuen and Tai Long Wan respectively. |
|
Re-creatability |
Moderate. |
|
Fragmentation |
Not fragmented. |
|
Ecological
Linkage |
High.
Continuous with surrounding forest and shrubland & grassland mixture. |
|
Potential
value |
High.
Have the potential to accumulate native plant and animal species. |
|
Nursery/Breeding
Ground |
No records of significant
nursery or breeding grounds were found during the survey on literature
review. |
|
Age |
Approximately 20 years. |
|
Abundance/Richness of Wildlife |
The abundance and richness of birds recorded
were moderate. |
|
Overall Ecological Value |
Moderate |
Table 6-3 Ecological Value
of Shrubland and Grassland Mixture in Study Area
|
Criteria |
Shrubland and Grassland Mixture |
|
Naturalness |
Moderate to Low. Natural
shrubland regenerated after hill fires 3 to 7 years ago. |
|
Size |
The total size of this habitat is approximately 29.2 ha. |
|
Diversity |
High in terms of floristic diversity but only moderate in structural
diversity. 56 plant species was
recorded within the habitat. |
|
Rarity |
Neither rare nor protected species were recorded during the survey. |
|
Re-creatability |
Readily re-creatable. |
|
Fragmentation |
Moderate. |
|
Ecological Linkage |
High. Continuous with surrounding forest and tall shrubland. |
|
Potential value |
Moderate. Have the potential
to accumulate native plant and animal species. |
|
Nursery/Breeding Ground |
No records of significant nursery or breeding
grounds were found during the survey or literature review. |
|
Age |
More than 20 years. |
|
Abundance/Richness
of Wildlife |
The abundance and richness of all wildlife recorded were low. |
|
Overall
Ecological Value |
Low |
Table 6-4 Ecological Value
of Wetland in the Study Area
|
Criteria |
Wetland |
|
Naturalness |
Moderate.
Semi-natural habitat formed from paddy field abandoned about 20 years
ago. |
|
Size |
The total size of this habitat is
approximately 14.7 ha. |
|
Diversity |
High in terms of floristic diversity but low
in structural diversity. 52 plant
species was recorded which is high compare to other wetland in Hong Kong. |
|
Rarity |
Four rare species to very rare species were
found (Azolla imbricata, Ceratopteris
thalictroides, Marsilea quadrifolia, and Salvinia natans), although they are mostly past paddy field
weeds. The habitat itself, however, is of high quality and rare because of
its size and species diversity and the high abundance of the locally rare Marsilea quadrifolia and Salvinia natans, both of which are
locally co-dominant at the center of the wetland. Although Fimbristylis
acuminata was listed as “rare” in Corlett et al. (2000), it is locally abundant in a number of wetland
sites in Hong Kong and should be in “restricted” category (S.C. Ng, pers.
comm.). Two bird species of
conservation concern including Greater Coucal Centropus sinensis and Red-billed Starling
Sturnus sericeus were recorded in the wetland habitat. Uncommon Chinese Bullfrog Rana rugulosa was also recorded
beside Stream S2 middle course. |
|
Re-creatability |
The habitat characteristics are difficult to
recreate. |
|
Fragmentation |
The habitat is less fragmented. |
|
Ecological
Linkage |
High.
Continuous with nearby brackish mudflat and wetland. |
|
Potential
value |
Low. |
|
Nursery/Breeding
Ground |
No records of
significant nursery or breeding grounds were found during the survey or
literature review. |
|
Age |
Approximately 30 years. |
|
Abundance/Richness of Wildlife |
The abundance and richness of all wildlife
recorded were high. |
|
Overall Ecological Value |
High |
Table 6-5 Ecological Value
of Abandoned Farmland and Farmland in Study Area
|
Criteria |
Abandoned Farmland |
Farmland |
|
Naturalness |
Moderate. Semi-natural habitat formed from paddy
field abandoned about 20 years ago. |
Low. Completely human dominated habitat with
some weedy species. |
|
Size |
The
total size of this habitat is approximately 4.5 ha. |
The
total size of this habitat is approximately 1.7 ha. |
|
Diversity |
Moderate
in terms of floristic diversity but low in structural diversity. 52 plant species was recorded which is
high compare to other wetland in Hong Kong. |
Low
in terms of floristic diversity and structural diversity. 16 plant species was recorded. |
|
Rarity |
Neither
rare nor protected species were recorded during the survey. |
Neither
rare nor protected species were recorded during the survey. |
|
Re-creatability |
Readily
re-creatable. |
Readily
re-creatable. |
|
Fragmentation |
Highly
fragmented. |
Highly
fragmented. |
|
Ecological
Linkage |
High. Continuous with nearby wetland. |
Low. |
|
Potential
value |
Moderate. May convert to wetland if undisturbed. |
Low. |
|
Nursery/Breeding
Ground |
No
records of significant nursery or breeding
grounds were found during the survey or literature review. |
No
records of significant nursery or breeding
grounds were found during the survey or literature review. |
|
Age |
Approximately
30 years. |
Approximately
10 years. |
|
Abundance/Richness of Wildlife |
The
abundance and richness of all wildlife recorded were low. |
The
abundance and richness of all wildlife recorded were low. |
|
Overall Ecological Value |
Moderate |
Low |
Table 6-6 Ecological Value of Terrestrial
Habitats in Rocky Shore and Sandy Beach in Study Area
|
Criteria |
Rocky Shore |
Sandy Beach |
|
Naturalness |
Moderate.
Natural habitat that had not been disturbed for 5 to 10 years. |
Moderate. Natural habitat that had not been
disturbed for approximately 5 to 10 years. |
|
Size |
The
total size of this habitat is approximately 4.4 ha. |
The
total size of this habitat is approximately 4.7 ha. |
|
Diversity |
Moderate
in terms of floristic diversity but low in structural diversity because of
sparse vegetation. 56 plant species
was recorded within the habitat. |
Moderate
in terms of floristic diversity but low in structural diversity. 32 plant species was recorded within the
habitat. |
|
Rarity |
One
locally rare species, Rhamnus
leptophyllus, was found in this habitat.
It had been confused, in the past, with R. brachypoda, a restricted species in HK. |
Pacific Reef Egret Egretta sacra
was recorded in the Pui O beach during the survey. |
|
Re-creatability |
Moderate
to High in terms of vegetative re-creatability. |
Moderate
to High in terms of vegetative re-creatability. |
|
Fragmentation |
Moderate. |
Moderate |
|
Ecological
Linkage |
Low. Continuous with surrounding tall
shrubland. |
Moderate. Continuous with surrounding backshore
shrubland. |
|
Potential
value |
Moderate |
Moderate |
|
Nursery/Breeding
Ground |
No
records of significant nursery or breeding
grounds were found during the survey or literature review. |
No
records of significant nursery or breeding
grounds were found during the survey or literature review. |
|
Age |
More
than 20 years |
More
than 20 years. |
|
Abundance/Richness of Wildlife |
The
abundance and richness of all wildlife recorded was low. |
The
abundance and richness of all wildlife recorded was low. |
|
Overall Ecological Value |
Low |
Low |
Table 6-7 Ecological Value
of Backshore Shrubland and Mangrove in Study Area
|
Criteria |
Backshore Shrubland |
Mangrove |
|
Naturalness |
Moderate
to low, because of high abundance of introduced tree species. |
High. Natural habitat that had not been
disturbed for more than 20 years. |
|
Size |
The
total size of this habitat is approximately 3.5 ha. |
The
total size of this habitat is approximately 1 ha. |
|
Diversity |
Moderate
to low in terms of floristic diversity and moderate in structural
diversity. Only 24 plant species were recorded. |
Moderate
in terms of floristic diversity and moderate to high in structural diversity
as the height of vegetation is comparable to tall shrubland. 28 species were recorded, which is
moderate compared to other mangroves in HK. |
|
Rarity |
Neither
rare nor protected species were recorded during the survey. Although one
rare plant species (Agave vivipara)
was recorded in the study, it is an introduced and naturalized species and so
is of no conservation importance. |
Neither
rare nor protected species were recorded during the survey. |
|
Re-creatability |
Readily
re-creatable. |
The
habitat is difficult to recreate. |
|
Fragmentation |
Moderate |
Moderate |
|
Ecological
Linkage |
Moderate. Continuous with nearby sandy shore and
wetland. |
Moderate. Continuous with nearby brackish mudflat
and wetland. |
|
Potential
value |
Moderate |
Moderate |
|
Nursery/Breeding
Ground |
No
record of significant nursery or breeding grounds were found during the
survey or literature review. |
No
record of significant nursery or breeding grounds were found during the
survey or literature review. |
|
Age |
More
than 20 years. |
More
than 20 years. |
|
Abundance/Richness of Wildlife |
The
abundance and richness of all wildlife recorded were low. |
The
abundance and richness of birds recorded were moderate. |
|
Overall Ecological Value |
Low |
High |
Table 6-8 Ecological Value
of Brackish Mudflat and Plantation in Study Area
|
Criteria |
Brackish Mudflat |
Plantation |
|
Naturalness |
High. Natural habitat. |
Low
to moderate. Completely human
dominated habitat with some weeds and secondary woodland species. |
|
Size |
The
total size of this habitat is approximately 4.2ha. |
The
total size of this habitat is approximately 8.7ha. |
|
Diversity |
Low
in terms of floristic diversity and structural diversity. 8 plant
species was recorded. |
Moderate
in terms of floristic diversity and high in structural diversity, as trees 3
to 6 m tall provide high habitat heterogeneity. 30 plant species was recorded. |
|
Rarity |
No
species of conservation importance were found in this habitat. |
No
species of conservation importance were found in this habitat. |
|
Re-creatability |
The
habitat characteristics are difficult to recreate. |
Readily
re-creatable. |
|
Fragmentation |
Less
fragmented. |
Heavily
fragmented. |
|
Ecological
Linkage |
High. Continuous with nearby brackish marsh and
wetland. |
Not
functionally linked with any important habitat. |
|
Potential
value |
Ecological
potential is low |
Ecological
potential is low. |
|
Nursery/Breeding
Ground |
No
record of significant nursery or breeding grounds were found during the
survey or literature review. |
No
record of significant nursery or breeding grounds was found in the survey or
literature review. |
|
Age |
More
than 20 years. |
Approximately
30 years. |
|
Abundance/Richness of Wildlife |
The
abundance and richness of birds recorded were moderate. |
The
abundance and richness of wildlife recorded were low. |
|
Overall Ecological Value |
High |
Low |
Table 6-9 Ecological Value
of Wasteland and Village Area in Study Area
|
Criteria |
Wasteland |
Village Area |
|
Naturalness |
Low. Heavily disturbed and disrupted by past
and current human activities. |
Low. Heavily disrupted and disturbed by human
activities. |
|
Size |
The
total size of this habitat is approximately 9.5 ha. |
The
total size of this habitat is approximately 96.7 ha. |
|
Diversity |
Moderate
in terms of floristic diversity but low in structural diversity. 31 species was recorded. |
Moderate
in terms of floristic diversity but low in structural diversity. 50 plant species was recorded but more
than half of them are either exotic, introduced, or cultivated/ornamental
species. |
|
Rarity |
Japanese
Pipistrelle Pipistrellus abramus was recorded near Ham Tin during the survey. |
Neither
rare nor protected species were recorded during the survey. |
|
Re-creatability |
Readily
re-creatable. |
Readily
re-creatable. |
|
Fragmentation |
Heavily
fragmented. |
Heavily
fragmented. |
|
Ecological
Linkage |
Not
functionally linked with any important habitat. |
Not
functionally linked with any important habitat. |
|
Potential
value |
Ecological
potential is low. |
Ecological
potential is low. |
|
Nursery/Breeding
Ground |
No
record of significant nursery or breeding grounds was found in the survey or
literature review. |
No
record of significant nursery or breeding grounds was found in the survey or
literature review. |
|
Age |
No
information and considered irrelevant. |
No
information and considered irrelevant. |
|
Abundance/Richness
of Wildlife |
The
abundance and richness of wildlife recorded were low. |
The
abundance and richness of wildlife recorded were low. |
|
Overall Ecological Value |
Low |
Low |
Table 6-10 Ecological Value of Stream Habitats in
Study Area
|
Criteria |
Stream |
|
Naturalness |
The
S4, upper course of S1 and S3 and lower course of S2 remain natural, while
the remaining sections are disturbed to a certain extent. |
|
Size |
The
length of S1, S2, S3 and S4 are approximately 0.8 km, 0.9 km, 50 m and 200 m respectively. |
|
Diversity |
The
wildlife observed in stream habitat was moderate to high in diversity. |
|
Rarity |
Vulnerable
freshwater fish Parazacco spilurus
(listed in China Red Data Book) and rare Atyid shrimp Caridina serrata were found in S1 and S4 respectively. |
|
Re-creatability |
The
stream habitats may be re-created but colonisation by stream fauna is not
guaranteed. |
|
Fragmentation |
Not
applicable. |
|
Ecological
Linkage |
High. Functionally linked to wetland,
particularly Pui O Marsh and Taro Bed. |
|
Potential
value |
The
potential value is moderate to low. |
|
Nursery/Breeding
Ground |
No
records of significant nursery or breeding grounds were found. |
|
Age |
Not
applicable. |
|
Abundance/Richness
of Wildlife |
The
aquatic faunal abundance and richness recorded were high. |
|
Overall Ecological Value |
Moderate |
Based on the ecological conditions presented in
the above sections, it is considered that the forest, brackish mudflat, wetland
and mangrove have high ecological value.
The abandoned farmland, tall shrubland, stream (S1 to S4) are regarded
to have moderate ecological value, while the other terrestrial habitats are
common and typical habitats in Hong Kong and most of the species identified are
common and widespread and therefore considered to be of low ecological value.
The list and evaluation of the floral and
faunal species of ecological interest recorded within the Study Area (Figures 6.5 - 6.8), according to the
EIA-TM, are given in Tables 6.11 and
6.12 below:
Table 6-11 Evaluation of Floral Species
of Ecological Interest Recorded within the Study Area
|
Species |
Growth Form |
Location |
Protection Status |
Distribution |
Rarity |
|
Ailanthus
fordii |
Tree |
Forest |
Protected in HK |
Ma On Shan, Tai O |
Rare |
|
Aquilaria
sinensis (Incense Tree) |
Tree |
Forest |
Class III national protection (Wu et al. 1988), Listed as “Vulnerable”
in the “China Plant Red Data Book” (Fu et
al. ). |
Widespread in Hong Kong |
Common |
|
Artocarpus
hypargyreus |
Tree |
Tall shrubland |
Class III national protection (Wu et al. 1988), Listed as “Vulnerable”
in the “China Plant Red Data Book” (Fu et
al. 1992). |
Widespread in Hong Kong. |
Common |
|
Azolla
imbricata (Water Fern) |
Giant herb |
Wetland |
Past paddy field weed, no protection status. |
Tai Po, Sha Tau Kok and Tan Chuk Hang |
Rare |
|
Ceratopteris
thalictroides (Water Fern) |
Herb |
Wetland |
Past paddy field weed, no protection status. |
Sam A Tsuen, Li Chi Chong, Kam Tin, Po Toi Island and Ping Chau (Mirs
Bay) |
Rare |
|
Cleisostoma
simondii (C. williamsonii, C. teres, Sarcanthus teretifolius) |
Epiphyte |
Tall shrubland |
Protected in HK (Forestry Regulations of the Forest
and Countryside Ordinance). |
Widespread in Hong Kong. |
Very common |
|
Cyclobalanopsis
glauca |
Tree |
Tall shrubland |
No protection status. |
Pok Fu Lam, Tai Tam, D’Aguilar Peninsula, Ma On Shan, Kai Kung Shan,
Sham Wat. |
Rare |
|
Gmelina
chinensis |
Tree |
Forest and tall shrubland |
Protected in Guangdong (Wu et al. 1988). |
Widespread in Hong Kong. |
Common |
|
Malaisia
scandens |
Climber |
Forest |
No protection status. |
Tong Fuk, Tai O, Soko Islands. |
Rare |
|
Marsilea
quadrifolia (Four-leaf Fern) |
Herb |
Wetland |
Past paddy field weed, no protection status. |
Not known to be found in other locality recently. |
Very rare |
|
Nepenthes
mirabilis (Pitcher Plant) |
Herb |
Tall shrubland |
Protected in HK. (Forestry Regulations of the Forest
and Countryside Ordinance). |
North Lantau and northwest New Territories. |
Common |
|
Rhamnus
leptophylla |
Shrub |
Rocky shore |
Previously confused with R. brachypodus, no protection status |
Unknown. |
Rare |
|
Salvinia
natans |
Giant herb |
Wetland |
Past paddy field weed, no protection status |
Hang Ha Po (Lam Tsuen). |
Rare |
|
Uncaria
hirsuta |
Climber |
Forest |
No protection status. |
Ma On Shan & vicinity, San Tau (Lantau). |
Rare |
|
Uvaria
calamistrata |
Climber |
Forest |
No protection status. |
Sunset Peak, Sham Wat, San Tau, Pak Mong and Nam Fung Road SSSI. |
Rare |
|
Urceola
micrantha (Parabarium micranthum, Ecdysanthera micrantha) |
Climber |
Forest |
No protection status. |
Mt Nicholson and Nam Fung Road fung shui wood. |
Rare |
|
Xenostegia
tridentata (Merremia hastata) |
Climber |
Forest |
No protection status. |
Specimen collected from Soko Island, Pok Toi &
Tuen Mun. |
Very rare |
Table 6-12 Evaluation of
Faunal Species of Ecological Interest Recorded within the Study Area
|
Species |
Common Name |
Location |
Protection Status |
Distribution |
Rarity in HK |
|
Unidentified
bat |
|
Near
brackish mudflat |
All
bats are protected |
Unknown |
Unknown |
|
Pipistrellus abramus |
Japanese
Pipistrelle |
Wasteland
near Ham Tin |
All
bats are protected |
Widespread in Hong Kong |
Common |
|
Centropus sinensis |
Greater Coucal |
Wetland
at Pui O |
All
birds are protected, Class 2 protected
wildlife of national importance in China and vulnerable
in China Red Data Book |
Widespread in Hong Kong |
Common |
|
Egretta sacra |
Pacific Reef Egret |
Pui
O beach |
All
birds are protected, Class 2 protected
wildlife of national importance in China and rare
in China Red Data Book |
Hong Kong’s coastal areas |
Common |
|
Milvus lineatus |
Black Kite |
Flying
over Pui O and Tai Long Wan tall shrubland |
All
birds are protected, Class 2 protected
wildlife of national importance in China |
Widespread in Hong Kong |
Very common |
|
Podiceps cristatus |
Great Crested Grebe |
Coastal
water outside estuary mouth. |
All
birds are protected, Class 2 protected
wildlife of national importance in China |
Deep Bay |
Uncommon |
|
Sturnus sericeus |
Red-billed Starling |
Wetland
at Pui O |
All
birds are protected, globally threatened species |
Deep Bay, Tai O and Long Valley |
Common, but localised |
|
Rana rugulosa |
Chinese
Bullfrog |
Pui
O Taro Bed and wasteland beside football pitch at Pui O |
Class
2 protected wildlife of national importance in China |
Sham Wat, Shui Hau, Mui Wo, Long Valley and New
Territories |
Uncommon |
|
Ptyas mucosus |
Common
Rat Snake |
Tall
shrubland near Shap Long Kau Tsuen |
Listed
as endangered in China Red Data Book. |
Widespread in Hong Kong, including Keung Fhan, Tong
Fuk and Mui Wo |
Common |
|
Parazacco spilurus |
Predaceous
chub |
Stream
S1 (upper course) |
Listed
as vulnerable in China Red Data Book |
Tung Chung, Wang Tong and Sha Lo Wan |
Common |
|
Heliophorus epicles |
Purple
Sapphire |
Forest
near Ham Tin |
No protection status |
Central to southeast Asia |
Uncommon |
|
Junonia hierta |
Yellow
Pansy |
Forest
near Ham Tin |
No protection status |
Central to southeast Asia |
Uncommon |
|
Junonia lemonias |
Lemon
Pansy |
Forest
near Ham Tin |
No protection status |
Central to southeast Asia |
Uncommon |
|
Junonia orithya |
Blue
Pansy |
Forest
near Ham Tin |
No protection status |
Central to southeast Asia |
Uncommon |
|
Ixias pyrene |
Yellow
Orange Tip |
Forest
near Ham Tin |
No protection status |
Central to southeast Asia |
Uncommon |
|
Caridina serrata |
Atyid
shrimp |
Stream
S4 |
No protection status |
Hong Kong Island and Lantau only |
Endemic,
Very rare |
The proposed 132 kV circuit alignment includes
five sections, Pui O Substation to Pui O Beach (Pui O portal) using underground
cable, Pui O Beach to Tai Long Wan east (Tai Long Wan portal) using cable
tunnel, Tai Long Wan east to Cheung Chau Sai Tai Road using submarine cable,
Cheung Chau Sai Tai Road to Cheung Chau South Station using underground cable
and Cheung Chau South Station to Cheung Chau North Substation using underground
cable. The sections using underground
cable will be buried underneath footpaths and/or roads, and the ground surface
will be reinstated afterwards. Impacts
due to habitat fragmentation and isolation therefore would not be
expected. Direct habitat/ area loss
would not be expected in the Pui O Marsh and Taro Bed, the listed ecological
sensitive receivers.
The potential impact associated with the
project will be:
· direct habitat loss of tall
shrubland, particularly within South Lantau Country Park, as a result of
construction of tunnel portal for the 132 kV circuit installation and the
related temporary work sites such as construction of platform, temporary access
road and slope work (Figures 6.9 & 6.10);
· direct loss of protected epiphyte Cleisostoma
simondii located at the Pui O portal (size of the
epiphyte patch is less than 50cm x 50 cm);
· indirect impact to the lower courses
of streams in the vicinity of the proposed 132 kV circuit due to construction
runoff;
· indirect impact to the surrounding
habitats and associated wildlife, particularly the identified rare/ protected
species, because of increased human activities/ disturbance such as storage or
dumping of construction material, or hill fire.
· indirect impact due to increased
human activities for the maintenance of the electric cable.
Potential impacts on terrestrial ecology
evaluated according to Table 1 of Annex 8 of the EIA-TM are given below:
Table 6-13 Overall Impact
Evaluation for Tall Shrubland
|
Evaluation Criteria |
Tall Shrubland |
|
Habitat
quality |
The
habitat quality of tall shrubland is moderate. |
|
Species |
There
may be potential direct or indirect impact to the wildlife inhabiting the
areas. The protected but common
epiphyte Cleisostoma
simondii located at the Pui O portal
will be affected. The patch of
epiphyte is small (50x50cm) and its loss is not considered to be significant. |
|
Size/Abundance |
Approximately
0.15 ha of tall shrubland at Pui O portal (750 m2) and Tai Long
Wan portal (700 m2) will be lost. |
|
Duration |
The
impact will persist during the construction and operational phases. |
|
Reversibility |
The
impact of direct habitat loss is irreversible. |
|
Magnitude |
The
scale of the habitat loss is small in the context of the surrounding similar
habitats. |
|
Overall
Impact Conclusion |
Low to Moderate |
Table 6-14 Overall Impact
Evaluation for South Lantau Country Park
|
Evaluation Criteria |
South Lantau Country Park |
|
Habitat
quality |
The
habitat being affected is tall shrubland with moderate quality. |
|
Species |
There
may be potential direct or indirect impact to the wildlife inhabiting the
areas. Neither rare nor protected
species will be affected. |
|
Size/Abundance |
Approximately
0.1 |
|
Duration |
The
impact will persist during the construction and operational phases. |
|
Reversibility |
The
impact of direct habitat loss is irreversible. |
|
Magnitude |
The
scale of the habitat loss is small in the context of the surrounding similar
habitats. |
|
Overall
Impact Conclusion |
Low to Moderate |
Table 6-15 Overall Impact Evaluation for Village
Area
|
Evaluation Criteria |
Village Area |
|
Habitat
quality |
The habitat quality of the village area is
low. |
|
Species |
The potential exists for direct or indirect
impacts to the wildlife inhabiting the areas. However, neither rare nor protected species will be affected. |
|
Size/Abundance |
Approximately 250 m2 will be lost. |
|
Duration |
The impact will persist during the
construction and operational phases. |
|
Reversibility |
The impact of direct habitat loss is
irreversible. |
|
Magnitude |
The scale of the habitat loss is small in the
context of the surrounding similar habitats. |
|
Overall
Impact Conclusion |
Low |
In conclusion, with the exception of the low to
moderate impact to the loss of tall shrubland located inside South Lantau
Country Park, as well as a
small patch of protected but common species Cleisostoma simondii, the
ecological direct impact due to the construction and operation of the 132 kV
cable circuits is expected to be low. The loss of the
small patch of common but protected epiphyte plant Cleisostoma
simondii, is not
considered a significant impact and does not require mitigation as the
species is common and the success of transplanting is considered questionable. Only a small
area (approximately 0.125 ha) of South
Lantau Country Park will be affected due to the construction of tunnel portals
(Pui O and Tai Long Wan) and the impacts are not expected to be
unacceptable. No direct impacts on the
Pui O Marsh and Taro Bed, the listed ecological sensitive receivers, will be
expected.
In general, the proposed 132kV cable circuits
will be located underneath the existing roads and footpaths. The construction activities are not expected
to cause disturbance to the habitats utilised by wildlife (including the
species of ecological interest).
Consequently, the direct impacts will be of low severity.
The potential indirect impacts (mainly noise
disturbance) to the surrounding habitats and associated wildlife, particularly
the species of ecological interest, due to the construction activities would
not expected to be high owing to the temporary nature and small scale of the
construction work given that regular checks on good construction practice will
be conducted. Given good construction
practice, silty runoff could be controlled and limited impacts would be
expected. No impacts during the
operational phase are expected.
The following mitigation measures to minimise
disturbance due to the project are recommended below.
·
Prevent
stream sedimentation during construction, particularly tunnel construction, by
erection of sediment barriers and operation of stilling ponds in streams which
could be potentially affected.
·
Erect
fences along the boundary of construction sites before the commencement of
works to prevent tipping, vehicle movements, and encroachment of personnel into
adjacent areas, particularly streams S1 to S4, forest beside the Pui O portal,
Pui O Marsh and Pui O Taro Bed.
·
Regularly
check the work site boundaries to ensure that they are not exceeded and that no
damage occurs to surrounding areas.
·
Treat
any damage that may occur to individual major trees in the adjacent area with
surgery.
·
Reinstate
temporary work sites/disturbed areas immediately after completion of the
construction by on-site tree/shrub planting.
Tree/shrub species used should take reference from those in the
surrounding area.
·
Prohibit
and prevent open fires within the site boundary during construction and provide
temporary fire fighting equipment in the work areas, particularly close to
forest areas.
There will be a loss of 0.15 ha of tall
shrubland (with moderate ecological value), mainly located
within South Lantau Country Park (0.12 ha), due to the construction of
tunnel portals (Pui O and Tai Long Wan).
The loss of part of the tall shrubland will be mitigated through scrub
compensatory planting. The actual loss
(tall shrubland and areas within South Lantau Country Park) will be considered
as a residual impact, however, its loss would be compensated through site shrub
planting. With implementation of the
above mentioned mitigation measures, no adverse residual impact is
expected.
The implementation of the terrestrial
ecological mitigation measures stated in Section
6.3.5 should be checked as part of the environmental monitoring and audit
procedures during the construction period as presented in the separate
Environmental Monitoring and Audit Manual.
Altogether 15 habitat types were found in the
Study Area, including forest, tall shrubland, shrubland-grassland mixture,
wetland, abandoned farmland, farmland, rocky shore, sandy shore, backshore
shrubland, mangrove, brackish mudflat, plantation, wasteland, village area and
stream. Based on the ecological
conditions presented in the above sections, it is considered that the forest,
wetland and mangrove have high ecological value. The brackish mudflat, abandoned farmland, tall shrubland, stream
(S1 to S4) are regarded as having moderate ecological value, while the other
terrestrial habitats are common and typical habitats in Hong Kong and most of
the species identified are common and widespread and therefore considered to be
of low ecological value.
The proposed 132 kV circuits will mainly be
located on existing road/ footpaths.
The impacts due to the construction and operation of the underground
cable are considered to be low, and no adverse residual impact is
expected. The most sensitive issue is
the direct habitat loss (0.125 ha of tall
shrubland) within the South Lantau Country Park, in which no unacceptable
residual impact will be expected.
Mitigation measures in the form of good construction practice and scrub
compensatory planting are recommended to minimise potential disturbance to the
surrounding environment.
The marine ecological impact
assessment was performed using relevant information from the literature and
field surveys. All coastal habitats were examined within the Study Area (covering any area within 500m
of the proposed work area), including intertidal and subtidal. Areas of ecological interest that would be
directly or indirectly affected by the proposed electric cable circuit
including intertidal natural rocky shore, intertidal sandy shore (natural and
modified), intertidal mudflat and mangrove were surveyed in more detail. All the intertidal ecological surveys were
undertaken between October and December 2000, and a dive survey focusing on the
subtidal hard bottom at Chi Ma Wan Peninsula was undertaken in November 2000.
The specific methodologies of surveys of
different habitats of ecological interest are presented below:
The main objective of this work was
to identify marine ecological assemblages of high ecological value or
conservation interest within the survey areas.
To fulfil this objective, dive surveys to search for corals and marine
fauna of conservation importance were conducted along the proposed cable
alignment. A reconnaissance survey
along the shore of the cable landing location was conducted to identify any
areas that support assemblages of corals (Octocorals and/or hard corals).
During the qualitative survey the
positions and depth of any areas that support coral assemblages were recorded
so that they could be surveyed quantitatively.
A quantitative dive survey was
undertaken at each of the proposed cable landing points (Figure 6.11).
Identification of the location of highest coral coverage along the Chi
Ma Wan sub-tidal shore was based on the results of the reconnaissance survey. At each location five 10 m transects running
parallel to the shore and one 100 m perpendicular transect along the proposed
cable alignment were surveyed. The ten
metre quantitative video transects were undertaken to ascertain the percentage
cover, colony density, species richness and diversity of corals at that
location. Categories of benthic attributes
used in the surveys are presented in Table 6.16. The outer seabed areas associated with each
cable route were also investigated by the use of 100 m perpendicular
transect. The 100 m transects were run
perpendicular to the shore to a distance deemed within safe limits for divers
given the high level of shipping traffic between Cheung Chau and Chi Ma Wan.
Photographs of representative coral
species located in the surveyed areas were taken using an underwater
camera. Video transects were recorded
at each of the survey sites. Each
transect was filmed at approximately 40cm above the substrate and at a constant
speed in compliance with standard protocols for coral surveys (no more than 10
metres per minute). The video transects
recorded a 40 cm swath of seabed. The
video camera was held perpendicular to the substrate to minimise parallax error
and to keep the substrate in focus.
The quantitative surveys were
conducted along each 10m transect at a depth range between
-1m to -7m PD dependent on where corals were observed to be most abundant
during the qualitative survey.
Information was recorded during the surveys concerning the physical
nature of the site. This information
consisted of observations regarding the degree of exposure of the site to wave
action, the nature of the substrate type and the topographic profile of the
site. Data on colony abundance of hard
corals and octocorals (soft corals and gorgonians) was extracted from the video
transects. Counts of colony
abundance of hard and soft corals were made for each site. Wherever possible, hard corals were
identified to species level by coral specialists using regional texts.
Table 6-16 Categories Used in the Quantitative
Surveys – Benthic Attributes
|
Ecological |
Substratum |
|
Hard
coral |
Bedrock |
|
Dead
standing coral |
Boulders |
|
Soft
coral (including gorgonians) |
Sediment
– sand and/or mud |
|
Anemone
beds |
Rubble
– dead coral fragments/shell |
|
Other
benthos: sponges, zoanthids, ascidians and bryozoans |
Cobbles |
|
Macro-algae |
|
Intertidal natural rocky shore surveys were
undertaken at three
locations on the Chi Ma Wan Peninsula to characterise the assemblages present
in the intertidal region. Rocky shore
organisms originated in purely marine habitats and have evolved and adapted to
live on intertidal shores. The extent
of their adaptations to this habitat will dictate where they are found on the
shore. The more adapted a species is to
terrestrial conditions the higher it will be found on the shore, causing
zonation patterns. The survey design
involved sampling throughout all of the intertidal zones so that the vertical
range of all species was represented.
At each site three 10 m wide horizontal (belt) transects were set up
along the shore (no less than 50 m apart) and surveyed at three heights up the
shore at 50 cm intervals perpendicular to the waterline starting at 1.5 m above
Chart Datum. On each transect, 6
quadrats (50 x 50 cm) were placed randomly to assess the abundance and
distribution of flora and fauna. All
animals found in each quadrat were identified and recorded to species level so
that density m-2 could be determined. Sessile organisms such as barnacles, oysters and algae in each
quadrat were not counted but estimated as percentage cover on the rock surface.
On the intertidal natural sandy shore near
Stream S3 at Pui O (Figure 6.12),
five line transects were deployed from the low tide mark up to the high tide
mark and the presence of organisms was noted.
No ecological survey was undertaken on the modified sandy shore (Pui O
Gazetted Bathing Beach), but additional five line transects were deployed
beside the beach near the interdial mudflat for reference. At five equidistant points chosen along each
of the transects, a 50 x 50 x 50 cm core was taken and all macrofauna visible
to the naked eye within the core were identified and recorded.
The intertidal mudflat at Pui O was surveyed at
three tidal-levels, low, mid and high.
At each tidal level, 5 quadrats (25 x 25 cm) were placed randomly to
assess the abundance and distribution of flora and fauna. All animals found in each quadrat were
identified and recorded to species level so that density m-2 could
be determined. Since all the recorded
mangrove were found on the intertidal mudflat, the mangrove was surveyed as a
part of the intertidal mudflat on the high tidal-level. The vegetative community of the mangrove has
been fully discussed in Section 6.3.2.
The marine ecological habitats in
the Study Area are mainly categorised into natural intertidal rocky shore,
intertidal sandy shore (natural and modified), artificial seawall, intertidal
mudflat, mangrove and subtidal habitats.
The coastal habitats are presented on Figure 6.12. Intertidal
field surveys were undertaken in December 2000 and the locations where field
surveys were conducted are shown on Figure
6.13.
Soft
Bottom Benthos
A study of benthic assemblages throughout Hong
Kong was undertaken by Shin & Thompson (1982). The study concluded that the western waters of Hong Kong supports
assemblages that are polychaete dominated (82.5 %). Species diversity at locations near the Study Area was ranked
intermediate (34.4 m-2) when compared with other areas in Hong Kong
(values ranging from 32.4 to 38.4 m-2). The mean number of individuals was 107.1 m-2 which is
higher than the average for Hong Kong (101.4 m-2) and the mean biomass
for the area was 23.9 g m-2, which is low compared to the overall
mean biomass for Hong Kong at 35.2 g m-2.
In March 2000 surveys were conducted of the
infauna present in and around the South Cheung Chau Open Sea Disposal Ground
(ERM 2000a). Some of the sampling
stations were close to Shek Kwu Chau just south of the Study Area. The surveys recorded fine grain sediments
that supported low abundance (405 m-2), and biomass (27.3 gm-2)
of infaunal assemblages that were dominated by polychaete worms, corophiid
amphipods and pinnotherid crabs.
Although the infauna were regarded as undisturbed the sediments
supported relatively low ecological value assemblages compared with other sites
in Hong Kong. It is expected that the
assemblages between Chi Ma Wan and Cheung Chau will be similar in composition
and hence ecological value.
Apart from its southern and eastern
shores, where the shallow subtidal area is initially rocky and coral-encrusted,
the seabed of Hong Kong is soft and comprises a mixture of sand and mud which
varies in detailed composition from place to place and under differing degrees
of current scour (Morton et al. 1995).
In northwestern areas, as shown in the Study Area, under the influence
of the Pearl River large quantities of silt are deposited regularly. The subtidal hard-bottom habitats are mainly
found in the Study Area fringing exposed coasts (ie Chi Ma Wan Peninsula). The benthic assemblages are a continuum of
those found in the lower shore of the littoral zone.
The general physical and biological description,
seabed composition, and percentage composition of identified benthos including
hard and soft corals of the three proposed cable
landing locations (Figures 6.14 to 6.16) are provided below:
Location A has a narrow (<10 m) subtidal nearshore boulder seabed to
a depth of -4 m C.D. The boulders were
of a large size 2-3 m diameter with wide vertical and horizontal surfaces and
all had silt coverage. The seabed
gently shelved to a depth of -6 m C.D. and consisted of scattered large
boulders with sand patches, once out from the nearshore area at a distance of
30 m the seabed was flat, barren and composed of fine sand/mud sediment.
The hard substratum was dominated by large boulders encrusted with
encrusting and ball sponges (Halichondria
spp., Callyspongia sp. and Tethya sp.), the common brown/orange
bryozoan (Order: Cheilostomata, Genus: Schizoporellidae), the green-lipped
mussel (Perna viridis), dead barnacles (Balanus
spp.) and rock oysters (Saccostrea
sp.). Large quantities of sea urchins (Anthocidaris crassispina and Temnopleurus
reevesi) and pink sea cucumbers
Colochirus crassus were also recorded. General observations of the
nearshore area revealed a few isolated colonies of soft and ahermatypic corals
including white whip corals (Euplexaura sp.,
majority were <3 cm tall), soft coral Dendronephthya
sp. and ahermatypic coral Tubastrea sp. Small, scattered and encrusting colonies of
the hard corals Psammocora superficialis and Cyphastrea
serailia were also recorded during the reconnaissance survey (Table 6-17).
The subtidal habitat was heterogeneous with
large sand and boulders patches as reflected by the large standard error in
percentage composition The abundance of hard coral (Psammocora superficialis and Cyphastrea serailia)
recorded was extremely low in the nearshore at 3.25 ± 6.5 %. A white whip gorgonian (Euplexaura sp.) and one orange whip gorgonian Euplexaura sp. were also recorded during the quantitative survey (Table 6-18).
Table 6-17 Percentage
Composition of Substratum and Associated Benthos Recorded along Transects at
Location A, B and C
|
|
Location A |
Location B |
Location C |
|||
|
|
Mean (%) |
SE |
Mean (%) |
SE |
Mean (%) |
SE |
|
Hard coral |
3.25 |
6.50 |
1.47 |
2.93 |
0.40 |
0.80 |
|
Boulders/bedrock |
56.82 |
33.69 |
88.13 |
10.72 |
74.00 |
9.05 |
|
Sand |
32.33 |
36.91 |
7.33 |
8.26 |
17.47 |
5.47 |
|
Mussel Perna viridis |
0.27 |
0.33 |
1.47 |
2.93 |
7.20 |
6.13 |
|
Sponge |
4.53 |
7.23 |
0.53 |
0.78 |
0.53 |
0.78 |
|
Bryozoan |
2.80 |
4.05 |
0.93 |
0.53 |
0.40 |
0.33 |
|
Algae |
- |
- |
0.13 |
0.27 |
- |
- |
Table 6-18 Species of Hard and
Soft Corals Recorded during Qualitative Survey within the Three Locations A, B
and C at Chi Ma Wan Peninsula
|
|
Location A |
Location B |
Location C |
|
Hard
Coral |
|
|
|
|
Psammocora
superficialis |
ü |
ü |
|
|
Cyphastrea
serailia |
ü |
|
ü |
|
Porites
lobata |
|
ü |
ü |
|
Goniopora
stutchburyi |
|
ü |
|
|
Oulastrea
crispata |
|
ü |
|
|
Soft
Coral |
|
|
|
|
Dendronephthya
sp |
ü |
|
|
|
Euplexaura
spp. |
ü |
ü |
ü |
The offshore seabed consisted of large boulders
and sand patches shelving gently to a depth of 8.5 m where the seabed was
barren and composed of fine sand/mud sediment.
Boulders were covered in a layer of sediment and dead encrusting
barnacles (Balanus spp.). There were several colonies of the
ahermatyic coral Tubastrea sp. and
one colony of the soft coral Dendronephthya
sp. (white body with red spicules).
Ten individuals of the white whip coral (Euplexaura sp.) were recorded and four orange whip corals (Euplexaura sp.). There were also several juvenile Euplexaura spp. noted. All gorgonians were isolated colonies and
not abundant. Location A recorded the
highest number of gorgonians for the three locations.
Similar to Location A there was a relatively narrow band of hard
substratum (large boulders) gently shelving to a barren sand seabed. The hard substratum had high sediment
deposit and was dominated by large boulders encrusted with sponges (Halichondria spp., Callyspongia sp. and Tethya sp.),
bryozoans, Perna viridis, dead large
barnacle shells (Balanus spp.) and
live rock oysters (Saccostrea sp.).
Extremely low percentage cover (1.47 ± 2.93 %) of hard coral, consisting
of scattered, encrusting colonies of Porites
lobata, Psammocora superficialis and Goniopora
stutchburyi, was recorded during the quantitative survey (Tables
6.17 & 6.18). The whip coral Euplexaura sp. and hard coral Oulastrea
crispata were also recorded from this location.
The perpendicular transect survey indicated the seabed was composed of
large boulders and sand patches, whereas the boulder surfaces were heavily
encrusted with dead barnacles (Balanus spp.)
and high sediment deposit. The benthos
recorded along the perpendicular transect included Perna viridis, encrusting sponges Halichondria sp., knobbly sponges Callyspongia spp., ball sponge Tethya
sp., bryozoans, rock oysters Saccostrea
sp. and short-spined sea urchins Anthocidaris
crassispina. A colony of whip coral Euplexaura sp. as well as several
discarded gill nets were also recorded during the survey.
Location C was the most northerly site surveyed at Chi Ma Wan
Peninsula. Similar to Location A and B
there was an extremely narrow band of hard substratum (medium-sized boulders)
gently shelving to a barren sand seabed.
A relatively low species diversity and abundance of benthos were
recorded in Location C.
The surfaces of the boulders were dominated by Perna viridis and barnacles. The hard coral coverage was the lowest
recorded among the three locations (0.40 ± 0.80 %), with only Porites lobata and Cyphastrea serailia recorded (Tables 6.17
& 6.18). One individual of whip coral Euplexaura sp. was recorded during the
survey.
No soft corals were observed along the
perpendicular transect during the survey.
Other organisms recorded included black short-spined Anthocidaris crassispina and decorator
urchins Temnopleura reevesi.
A narrow band of large-medium sized boulders
dominated the nearshore subtidal areas of the three proposed cable landing
locations at Chi Ma Wan Peninsula. A
high sediment deposit was observed on all hard substrate surfaces and the
existing benthos dominated by encrusting organisms such as barnacles (dead),
rock oysters, sponges and bryozoans.
Hard and soft coral coverage was extremely low with scattered
distribution. Location A possessed the
highest number of soft corals and percentage cover of hard corals although the mean
value was less than 4 %.
In 1999 dive surveys were conducted around
Penny’s Bay, Pa Tau Kwu and Sze Pak Wan as part of the Theme Park EIA (ERM
2000b). The coral community at Penny’s
Bay was composed of a shallow, thin veneer of common faviid coral species. Twelve hard coral species were recorded and
percent live coral cover was generally low (9%), however, the inner part of
Penny’s Bay appeared to still support a relatively healthy, simple coral
community. When compared to other sites
in Hong Kong, especially those in the western harbour area, the assemblages
were composed of a high number of coral colonies with a medium to high
percentage cover and classified as of high ecological value. In comparison to areas of conservation value
in the eastern waters of Hong Kong, such as South Ninepin Island or Ping Chau,
the assemblages were of lower diversity and abundance. Surveys
conducted by AFCD in the western waters of Hong Kong have reported the hard
coral species recorded along the Chi Ma Wan coastline from a number of other
locations, including Peng Chau, Kau Yi Chau, Siu Kau Yi Chau, Chau Kung To, Tai
Lei and Silver Island. The findings of
the AFCD surveys emphasise the widespread nature of the corals recorded in the
present study.
The results of the present survey at Chi Ma Wan
recorded soft and hard coral assemblages of lower abundance and diversity than
those at Penny’s Bay
and consequently are assigned a lower ecological value.
Rocky shore organisms originated in
purely marine habitats and have evolved and adapted to live on intertidal
shores. The extent of their adaptations
to this habitat will dictate where they are found on the shore. The more adapted the species is to
terrestrial conditions, the higher it will be found. This causes zonation patterns.
Their recruitment period and the primary productivity of the shore will
affect the abundance of intertidal organisms.
Typical exposed rocky shore communities consist of periwinkles,
barnacles and limpets. Encrusting algae
are common in the low intertidal zone.
In total, 15 species of animals and 3 species
of macroalgae were recorded on the rocky shores within the Study Area. Animals recorded on the shores at the
surveyed sites were largely molluscs.
The most abundant were herbivorous molluscs, including the limpets (Notoacmaea schrenkii, Patelloida saccharina and Cellana toreuma) on the mid (2.0 m above
Chart Datum) and low (1.5 m above CD) shore, and the periwinkles (Nodilittorina radiata, N. vidua and N. trochoides) on the high (2.5 m above CD) and mid shore. The predatory gastropod Thais clavigera (the common dogwhelk) was also recorded in the low
shore region. Sessile filter-feeding
barnacles such as the acorn barnacle (Tetraclita
squamosa) were also common on the shores (Table 6-19). Macroalgae (Hildenbrandia occidentalis, Ulva fasciata and Corallina
sp.) and Bivalves such as the mussels (Septifer
virgatus) and the rock oyster (Saccostrea
cucullata) were also seen on the shores but in low abundances.
Table 6-19 Density (m-2)
of Intertidal Fauna and Percentage Cover (%) of Sessile Fauna and Flora
Recorded at South-east of Chi Ma Wan Peninsula
|
Species |
Location A |
Location B |
Location C |
|
Snail |
|
|
|
|
Nodilittorina radiata |
181.78 |
107.11 |
80.00 |
|
Nodilittorina vidua |
97.56 |
28.22 |
22.89 |
|
Nodilittorina trochoides |
4.89 |
0 |
0 |
|
Thais clavigera |
0.44 |
0.44 |
2.44 |
|
Monodonta labio |
0 |
0.22 |
0 |
|
Limpet |
|
|
|
|
Cellana grata |
0.67 |
1.33 |
0.89 |
|
Cellana toreuma |
6.22 |
3.11 |
4.89 |
|
Notoacmaea shrenkii |
20.89 |
16.22 |
18.44 |
|
Patelloida saccharina |
7.33 |
19.33 |
16.22 |
|
Siphonaria japonica |
0 |
0 |
1.11 |
|
Chiton |
|
|
|
|
Acanthopleura japonica |
0.22 |
2.67 |
8.67 |
|
Barnacle (% cover) |
|
|
|
|
Tetraclita squamosa |
13.2 |
19.4 |
20.2 |
|
Capitulum mitella |
0.3 |
0.8 |
3.2 |
|
Bivalve (%cover) |
|
|
|
|
Septifer virgatus |
0 |
0.4 |
6.4 |
|
Saccostrea cucullata |
0.7 |
2.1 |
0.1 |
|
Macroalgae (%cover) |
|
|
|
|
Hildenbrandia occidentalis |
4.3 |
1.6 |
0 |
|
Ulva fasciata |
0 |
0 |
0.1 |
|
Corallina sp. |
1.0 |
1.7 |
0 |
In the lee of headlands or within
shallow bays, wave action is reduced and there is an accumulation of sand and
detrital material. Exposed sandy
beaches are relatively unstable environments and the fauna is sparse. However, with increasing shelter substrate
stability allows for the development of a rich community of burrowing
animals. Where a river or stream
discharges to a sandy shore, forming an estuary, a greater percentage of very
small particles are found, due to the deposition of terrigenous material eroded
by the river. Such shores retain water
more readily and the beach comprises black, organic-rich or compacted mud. Typical sandy shore communities consist of
numerous species of burrowing crabs, potamid gastropods (e.g. Batillaria multiformis), bivalves and
worms.
The Study Area contains several
small sandy shore areas which are illustrated on the habitat map presented on Figure 6.12. Only one organism, the bivalve Fulvia mutica,
was recorded in the sandy shore close to the proposed portal area at Pui O
during the survey.
Pui O Beach is the only gazetted
beach found within the Study Area. It
was the beach of water quality categorised as "Good" under EPD's
Beach Water Quality Monitoring Programme (EPD, 1999). Beaches that have been developed for recreational use (such as
that at Pui O) appear almost devoid of life (Morton et al 1996). The exception to this are wave exposed
beaches in the surf where unique assemblages of surf clams, mole crabs and
hermit crabs are present. No beaches of
this type are found in the Study Area.
The majority of the coastal areas on Cheung
Chau have been reclaimed and lined with vertical artificial seawalls. Few surveys have been conducted on the
colonization of organisms on artificial seawalls in Hong Kong, however, fouling
organisms have been anecdotally recorded as common on artificial seawalls,
wharf files and other marine structures (Morton & Morton 1983; Huang et al.
1992; Binnie 1996, 1997). Various
species of algae, coelenterates, ascidians, bryozoans, sponges, crustaceans,
molluscs and polychaetes are also commonly observed on these artificial
structures. Therefore, it can be
presumed that species commonly found on these surfaces in Hong Kong waters will
be found on the artificial seawalls within the Study Area.
Mudflats are usually found where a river or
stream discharges freshwater into a bay, and the eroded soil carried by streams
is deposited as mud or silt. In
general, the upper part of a mudflat develops into mangrove in tropical
areas. The fauna of soft mud flats
consists of mudskippers, grapsid and sesarmid crabs and a few browsing ceriths
on the surface with burrowing bivalves and worms as the infauna (Morton &
Morton 1983).
The substrata of the mudflat at Pui O is
composed of mud and sand. Findings of
the surveys for this Study indicated that the mud flat fauna was dominated by
the snails, including the cerithid (Cerithidea
djadjariensis), the neritid (Clithon oualaniensis) and the nassarid (Nassarius festivus). Fiddler crabs (Uca spp.) and potamid (Batillaria multiformis) were also common on the mud flat (Table 6-20). The mudflat (approximately 4.2 ha) is likely to be less disturbed
with good conditions. The ecological
value of the habitat is regarded as high based on the results obtained from the
site survey.
Table 6-20 Density (m-2)
of Intertidal Fauna Recorded on Mudflat at Pui O
|
Species |
High Tidal Level (incl. mangrove) |
Mid Tidal Level |
Low Tidal Level |
|
Molluscs |
|
|
|
|
Batillaria multiformis |
0 |
3.2 |
9.6 |
|
Cerithidea djadjariensis |
0 |
275.2 |
89.6 |
|
Cerithidea microptera |
9.6 |
0 |
0 |
|
Clithon spp. |
0 |
0 |
265.6 |
|
Terebralia sulcata |
6.4 |
0 |
0 |
|
Nassarius festivus |
0 |
25.6 |
150.4 |
|
Crustacean |
|
|
|
|
Uca chlorophthalmus crassipes |
25.6 |
0 |
0 |
|
Uca lactea |
0 |
22.4 |
0 |
|
Pseudosesarma patshuni |
3.2 |
0 |
0 |
|
Hermit crab |
0 |
0 |
6.4 |
Mangroves are regarded as of ecological
importance as they provide food, shelter and breeding grounds for various
pelagic and coastal fisheries and birds (Tam & Wong 1997). The EIA-TM (Annex 8) indicates that established mangrove stands of any size
should be regarded as important habitat types and, therefore, require
ecological impacts assessments to be performed. In Hong Kong, the number and area of mangrove habitats in Hong
Kong has been greatly reduced in the past due to reclamation and infrastructure
development over the past decades (Tam & Wong 1997).
Mangrove refers to habitats with woody
vegetation dominated by salt-tolerant species found on inter-tidal areas. Three patches of mangrove (with total 1 ha)
were found at Pui O. Major mangrove
species found in the Study Area included Excoecaria
agallocha, Kandelia candel and Aegiceras corniculatum, for details of
the floristic and structural diversity of the mangrove refer to Section 6.3.2.
Marine Mammals
The review below is based on stranding records
collected in Hong Kong since 1973 (Parsons et al. 1995), and detailed studies
conducted on the ecology of Hong Kong's small cetaceans since 1994 (Jefferson
1997; Jefferson and Leatherwood 1997; Parsons 1997; Jefferson 1998; Parsons
1998; Jefferson and Braulik 1999; Hung 2000; Jefferson 2000). The Indo-Pacific Humpback Dolphin, Sousa chinensis, and the Finless
Porpoise, Neophocaena phocaenoides,
are the only species of marine mammal regularly sighted in Hong Kong waters.
Indo-Pacific Humpback Dolphin (Sousa chinensis)
Humpback dolphins (also known locally as
Chinese white dolphins) are found in all the waters surrounding Lantau Island
(Parsons et al. 1995; Jefferson 2000),
whilst the area to the north of Lantau appears to be by far the most important
habitat in Hong Kong. North Lantau is
heavily used in all seasons, and the western portion of the North Lantau area
has high densities of dolphins throughout the year (Jefferson 1998, 2000). North Lantau is the only place in Hong Kong
where dolphins are seen year round.
Pods of dolphins are most frequently sighted in the western part of
these waters around the Sha Chau and Lung Kwu Chau Marine Park and the Chek Lap
Kok platform.
The South Lantau and East Lantau areas are used
much less extensively and only appear to be important seasonally. The waters to the south of Penny's Bay and
east of the Pa Tau Kwu and Fa Peng shores showed a seasonal pattern in
sightings of the dolphin (Jefferson 1997).
Dolphins do not normally appear to use the area in spring or early
summer and they were largely observed during autumn and winter months. However, their abundance and density
recorded in the area were very low when compared to North Lantau (the highest
East Lantau sighting rate was only 15% of the yearly average for North
Lantau).
South Lantau (mainly the western portion around
Fan Lau and the Sokos Islands) is used by dolphins primarily in the summer and
autumn seasons, when there are estimated to be 20 and 17 dolphins present,
respectively (only about 3 dolphins are estimated to be present in winter, and
none in spring - Jefferson 2000).
Individual movements and ranging patterns of
dolphins have recently been investigated (Hung 2000). It was found that, while most dolphins apparently do not use the
East Lantau area, some individuals that occur primarily in North Lantau use the
East Lantau area as part of their range.
At least one individual that used to occur primarily in East Lantau
(EL07) may have shifted its home range to the North Lantau area (Hung
2000). As the waters within and in
proximity of the Study Area show few sightings of dolphins (Figure 6.12), the area does not appear
to be highly utilised by dolphins.
Therefore, it is unlikely that this area contains critical Sousa chinensis habitat.
Finless Porpoise (Neophocaena phocaenoides)
Finless porpoises occur in the waters to the
south and east of Lantau Island (Parsons et al. 1995; Jefferson and Braulik
1999). The entire South Lantau area is
used seasonally by finless porpoises in winter and spring, when there are
estimated to be 10 and 25 porpoises present, respectively (Jefferson and
Braulik 1999). Interestingly, these are
the seasons when humpback dolphins are not present in the area. Both strandings and sightings indicate that
East Lantau is used by finless porpoises (Parsons et al. 1995; Jefferson and
Braulik 1999). No sightings of Finless
Porpoise have been recorded within the Study Area and only a few sightings were
observed in the vicinity of the Study Area (Figure 6.12). The marine
waters are thus unlikely to contain critical habitats for Neophocaena phocaenoides.
According to the EIA-TM Annex 8 the ecological value/importance of a habitat can be
evaluated using the following criteria:
·
Naturalness;
·
Size;
·
Diversity;
·
Rarity;
·
Re-creatability;
·
Ecological
Linkage;
·
Potential
value;
·
Nursery
Ground;
·
Age;
and,
·
Abundance.
The criteria listed above have been applied to
the information gathered or reviewed on the marine ecology of the subtidal soft
bottom benthic habitats within the Study Area in order to determine their
ecological value. The application of
these criteria has led the habitat to be classified as of low ecological value
(Table 6-21).
Table 6-21 Ecological Value
of the Subtidal Soft Benthos Assemblages within the Study Area
|
Criteria |
Subtidal Soft Benthos |
|
Naturalness |
The habitat between Chi Ma Wan Peninsula and Cheung Chau (ie of the
Adamasta Channel) where the submarine cables will be laid is a navigation
channel and is, therefore, subject to propeller scour disturbance. |
|
Size |
The
submarine cable laying works will involve the loss of 0.5 hectares of soft
bottom subtidal habitats along the submarine cable alignment. |
|
Diversity |
The
assemblages are of similar diversity when compared to other areas of Hong
Kong. |
|
Rarity |
No
organisms were found that are considered as rare. |
|
Re-creatability |
The
habitat cannot be re-created on site. |
|
Ecological
Linkage |
The
surrounding environment contains many other areas of soft substrate. |
|
Potential
Value |
It
is unlikely that the site can develop conservation interest. |
|
Nursery
Area |
None
identified in the review. |
|
Age |
The
fauna appear to be typical of those present in Hong Kong's soft benthos. The sediments in the habitat are
constantly accreting and eroding and the fauna present there are typically
short lived (less than 2 years). |
|
Abundance |
Abundances
appear to be similar when compared to other areas of Hong Kong. |
|
SUMMARY |
The sediments support average diversity and
abundance of benthic organisms that are typical of Hong Kong's benthos. Ecological Value - Low. |
Note: n/a: Not
Applicable
The criteria listed above have been applied to
the information gathered or reviewed on the marine ecology of the subtidal
hard-bottom benthic habitat within the Study Area. The habitat has been classified as of low ecological value (Table 6-22).
Table 6-22 Ecological Value
of the Subtidal Hard-Bottom Habitat within the Study Area
|
Criteria |
Subtidal Hard-Bottom
Habitat |
|
Naturalness |
There is evidence at the site of indirect impacts to the assemblages
through poor water quality and deposited sediments. |
|
Size |
The assemblages extend along the entire
length of the natural rocky coast of Chi Ma Wan Peninsula (approx. 10 km),
but are found along a narrow band at depths of 3 - 4 m below chart datum. |
|
Diversity |
A total of five species of hard corals and
two species of soft corals were recorded within the Study Area, which
represents a relatively low diversity.
|
|
Rarity |
All
of the species of
corals are commonly recorded on rocky coasts in the western and eastern
waters of Hong Kong. |
|
Re-creatability |
The habitat can be recreated through the
deployment of artificial reefs. |
|
Ecological Linkage |
It is suspected that the surrounding
environment contains similar subtidal habitats. |
|
Potential Value |
It is unlikely that the site can develop
conservation interest. |
|
Nursery Area |
None identified during the literature review
or field surveys. |
|
Age |
The subtidal fauna is generally short lived
apart from the isolated colonies of hard corals which are slow growing and
long lived. |
|
Abundance |
Abundances of hard and soft corals appear to
be of low abundance when compared to the western as well as the eastern
waters of Hong Kong. |
|
SUMMARY |
The
subtidal fauna appears to be of low diversity and abundance with few colonies
of hard and soft corals present. Ecological Value - Low. |
Note: n/a: Not
Applicable
The criteria listed above have been applied to
the information gathered or reviewed on the marine ecology of the intertidal
habitats within the Study Area in order to determine their ecological
value. The application of these
criteria has led the intertidal mudflat and mangrove to be classified as high,
intertidal rocky shores as medium, whereas, the intertidal sandy shores and
artificial seawall have been classified as of low ecological value (Tables 6.23 to 6.25).
Table 6-23 Ecological Value
of Intertidal Mudflat and Mangrove Within the Study Area
|
Criteria |
Intertidal Mudflat |
Mangrove |
|
Naturalness |
The
habitat is relatively undisturbed by human impact. |
The
mangrove is relatively undisturbed by human impact. |
|
Size |
The total size of the intertidal mudflat is
approximately 4.2 ha. |
The total size of the mangrove is
approximately 1 ha. |
|
Diversity |
The intertidal communities are typical of
mudflat in Hong Kong. |
The intertidal communities are typical of
mangrove in Hong Kong. |
|
Rarity |
No species recorded are considered rare. |
No species recorded are considered rare. |
|
Re-creatability |
The habitat can be re-created. |
The habitat can be re-created. |
|
Ecological Linkage |
The surrounding environment contains few
similar intertidal habitats. |
The surrounding environment contains few
similar intertidal habitats. |
|
Potential Value |
The site can develop conservation interest. |
The site can develop conservation interest. |
|
Nursery Area |
Mudflats are reported to be nursery habitats
for many species. |
Mangroves are reported to be nursery habitats
for many species. |
|
Age |
n/a for these assemblages as the life cycle
of the fauna is very short. |
Unknown.
The mangroves trees were mature and in good condition. |
|
Abundance |
Assemblages showed moderate abundance and
appear to be typical of other intertidal mudflats in Hong Kong. |
Assemblages showed moderate abundance
and appear to be typical of other
mangroves in Hong Kong. |
|
SUMMARY |
The intertidal mudflat supported assemblages
similar to other mudflats in Hong Kong. The habitat appears to have suffered
little human disturbance. Ecological Value - High. |
The mangrove supported assemblages similar to
other mangroves in Hong Kong. The
habitat appears to have suffered little human disturbance. Ecological
Value - High. |
Note: n/a: Not
Applicable
Table 6-24 Ecological Value
of Rocky Shore and Sandy Shore Within the Study Area
|
Criteria |
Rocky Shore |
Sandy Shore |
|
Naturalness |
The
habitat is undisturbed by human impact due to the steep rocky terrain of much
of the intertidal zone and remoteness of the shore. |
The
sandy shore at Tai Long is relatively undisturbed by human impact due to its
remoteness. The
sandy shore at the Pui O Portal is relatively undisturbed due to its
remoteness. The
sandy beach at Pui O is highly disturbed by human impacts through development
for recreation as a gazetted beach. |
|
Size |
The area covers almost the entire length of
Chi Ma Wan Peninsula (approx. 10 km). |
The shore at Tai Long is approx. 500 m. The shore at the Pui O Portal is approx. 200
m. The Pui O Beach is approx. 900 m. |
|
Diversity |
The intertidal communities are typical of
exposed rocky shores in Hong Kong. |
Field surveys show that the sandy shore at
the Pui O Portal are of low species diversity. The shore at Tai Long Wan is likely to support assemblages of
similar diversity. Assemblages at the Pui O gazetted beach are
thought to be of low diversity as it is a highly disturbed habitat. |
|
Rarity |
No species recorded are considered rare. |
No species recorded are considered rare. |
|
Re-creatability |
The habitat can be re-created. |
The habitat can be re-created. |
|
Ecological Linkage |
The surrounding environment contains similar
intertidal habitats. |
The surrounding environment contains few
other similar intertidal habitats. |
|
Potential Value |
Unlikely that the site can develop
conservation interest. |
Unlikely that the site can develop
conservation interest. |
|
Nursery Area |
None identified during the literature review
or field surveys. |
None identified during the literature review
or field surveys. |
|
Age |
n/a for these assemblages as the life cycle
of the fauna and flora is very short. |
n/a for these assemblages as the life cycle
of the fauna is very short. |
|
Abundance |
Assemblages were of moderate abundance and
appear to be typical of other exposed shores in Hong Kong. |
Assemblages at the Pui O Portal were of low
faunal abundance. This finding is
typical of semi-exposed sandy beaches in Hong Kong. The shore at Tai Long Wan is likely to support assemblages of
similar abundance. Reviewed literature indicates that gazetted
beaches that are frequently used for recreational purposes supporting low
abundance of organisms. |
|
SUMMARY |
The fauna of the intertidal region appears to
be typical of exposed shores in Hong Kong.
The sites appear to have suffered little human disturbance. Ecological Value - Medium. |
The sandy shores at Tai Long Wan and the Pui
O Portal support assemblages of low diversity and abundance and are typical
of other semi-exposed beaches in Hong Kong.
Literature reviews indicate that the gazetted
beach at Pui O is likely to support low faunal diversity and depauperate
assemblages typical of other recreational beaches in Hong Kong. Ecological
Value - Low. |
Note: n/a: Not
Applicable
Table 6-25 Ecological Value of the Artificial
Seawalls in the Study Area
|
Criteria |
Artificial Seawalls |
|
Naturalness |
The
habitat is disturbed by human impacts through stormwater discharges and development
of residential & industrial areas. |
|
Size |
The Cheung Chau artificial seawall is
approximately 1.2 km long, the majority of which is vertical. |
|
Diversity |
Reviewed literature indicates that sloping
artificial seawalls support similar assemblages to natural intertidal
shores. Vertical seawalls, however,
support lower diversity than natural shores.
Corals have been reported colonising the subtidal sections of sloping
artificial seawalls in North Lantau. |
|
Rarity |
No rare species were reported in the literature
reviewed. |
|
Re-creatability |
The habitat can be re-created. |
|
Ecological Linkage |
The surrounding coastlines are composed of a
mixture of natural and artificial intertidal shores. |
|
Potential Value |
The site can develop conservation interest if
over time and under favourable conditions it becomes colonised by hard or
soft corals. |
|
Nursery Area |
None identified during the literature review. |
|
Age |
The seawalls were constructed more than 10
years ago. |
|
Abundance |
Reviewed literature indicates that artificial
seawalls support similar assemblages to natural intertidal shores. Corals have been reported colonising the
subtidal sections of sloping artificial seawalls (e.g. tetrapods, dolosse
blocks or rubble mound) where water quality is good. |
|
SUMMARY |
The fauna of the intertidal region of the
artificial seawalls are reported to support similar diversity and abundance
of intertidal organisms as natural seawalls.
Subtidal portions of sloping seawalls can also support coral growth,
however, this depends on the age of the seawall and environmental conditions
of the area. The Cheung Chau seawalls
are largely vertical and as such do not support communities of more than low
ecological value. The breakwaters of
the Cheung Chau Typhoon Shelter are unlikely to support assemblages that are
of more than low ecological value as the waters in the typhoon shelter are
generally subject to pollution due to vessels, storm-drains and
surface-runoff. Ecological Value - Low. |
The same assessment criteria have been applied
to the marine waters within the Study Area with regard to the usage of the area
by protected species of marine mammals.
This habitat has been classified as of low ecological value depending
largely on the use of the area by protected species of marine mammals (Table 6-26).
Table 6-26 Ecological Value of the Marine Waters
within the Study Area
|
Criteria |
Marine Waters between Chi
Ma Wan Peninsula and Cheung Chau |
Marine Waters off Pui O |
|
Naturalness |
Disturbed
as a result of fishing activities and in close proximity to some of the
busiest shipping lanes in Hong Kong. |
Disturbed
as a result of recreation activities at the Pui O gazetted beach. |
|
Rarity |
No dolphins or porpoises have been recorded
in the immediate area. |
No dolphins or porpoises have been recorded
in the immediate area. |
|
Re-creatability |
n/a |
n/a |
|
Ecological Linkage |
Preferred marine mammal habitat occurs to the
north and west of Lantau. |
Preferred marine mammal habitat occurs to the
north and west of Lantau. |
|
Potential Value |
Limited value due to heavy navigational use
of the area. |
Limited value due to heavy recreational
activities in the area. |
|
Nursery Area |
No nursery areas were identified in the
review of baseline conditions. |
No nursery areas were identified in the
review of baseline conditions. |
|
Abundance |
Marine mammals have not been recorded within
the immediate area. |
Marine mammals have not been recorded within
the immediate area. |
|
SUMMARY |
No marine mammals have been sighted in the
immediate area. Ecological
Value - Low for both species. |
No marine mammals have been sighted in the
immediate area. Ecological
Value - Low for both species. |
·
High ecological value mangrove habitat at
Pui O.
·
High ecological value intertidal mudflat
assemblages at Pui O.
·
Medium ecological value intertidal
rocky shores at Tai
Long Wan Landfall.
Impacts to marine ecological resources arising
from the construction works may be divided into those due to direct
disturbances to that habitat and those due to perturbations to key water
quality parameters.
The submarine cables will be
covered by concrete slabs of approximate dimensions 2m(W)x3m(L)x0.3m(D) as
protection against maintenance dredgers. They will be placed on
the seabed by barge and crane or diver. The
concrete slabs will gradually be affected by natural sedimentation patterns in
the area and covered, thereby re-establishing the base stratum. It takes about
3 months to complete the installation of protective concrete slabs.
Artificial Seawalls
(Breakwater): The proposed submarine cables will
pass through the existing breakwater of the Cheung Chau Typhoon Shelter. Armour rock of the breakwater will be
temporarily removed for laying the proposed submarine cables. The submarine cables will be laid on precast
concrete trough and protected with concrete prior to backfill with armour rock
to the original status. As breakwaters
are artificial habitats and support assemblages of low ecological value, and
they will be backfilled with armour rock to the original status once the cable
laying works are complete, no adverse direct impacts to the artificial habitat
are likely to occur.
Subtidal Hard Bottom
Habitats: For the landfall at Tai Long Wan a concrete
cable trough will be used for installing the shore end segment of the proposed
submarine cables. Protective cover may
be required for protecting the submarine cables when located at shallow water
at Tai Long Wan. Field surveys indicate
that the subtidal hard bottom habitats support assemblages of low diversity and
abundance with few colonies of hard and soft corals present. As the cable will be installed by means of
cable trough, which is small in diameter (approx. 0.3 m), it is anticipated
that the direct impacts to the low ecological value subtidal hard bottom
habitats are unlikely to be severe.
Intertidal Habitats:
Field surveys undertaken at the rocky shores at the Tai Long Wan
landfall site show that the habitats support intertidal communities that are
typical of exposed rocky shores in Hong Kong and are considered as of medium
ecological value. The proposed cable
landing works at the Tai Long Wan landfall will only affect a small area of the
habitat which is unlikely to represent an unacceptable ecological impact. Over time it is expected that rocky shore
organisms will colonise the concrete covered cable trough and similar
communities will be re-established.
The proposed
reclamation works temporary
working platform at the Pui O Portal will result in the temporary loss of 0.01855 ha intertidal sandy shore
habitats. The sandy shore survey
conducted at the proposed Portal site indicates that the habitat supports
assemblages that are of low diversity and abundance and is considered to be of
low ecological value. As the area to be
directly affected by the formaproposed
reclamation works temporary construction of thea temporary working platform, which will be reinstated upon
completion of excavation of the tunnel is of low ecological value
and is small in size (0.018 ha ha),
the impact is considered as acceptable.
No direct loss
of habitat will occur at the high ecological value mangrove or mudflat at Pui
O.
Indirect Impacts
·
increased concentrations of suspended
solids (SS);
·
a resulting decrease in DO
concentrations; and,
·
an increase in nutrient concentrations in
the water column.
Suspended Solids (SS)
Subtidal Soft Benthos: Sessile organisms within the
benthos will be susceptible to the effects of increased sediment loads. Effects can be lethal or sublethal (e.g.
reduction in reproductive potential due to stress incurred by constantly having
to flush out the depositing material).
The effects of sedimentation on organisms will also depend on other
factors, such as an organism's tolerance, growth orientation of sessile
organisms and water movement. Infaunal
benthic assemblages in Hong Kong are located in soft muds and sands which are
frequently disturbed by storms, seabed currents and constant trawling activity
which reworks the sediments creating high suspended sediments loads in the
water column. Benthic invertebrates
are, therefore, unlikely to be adversely affected by the proposed
reclamation activities formation of thea temporary working platform at
the Pui O Portal and the submarine cable laying works in the Adamasta Channel.
The water quality
assessment undertaken for the proposed Project indicates that the potential
water impacts associated with the proposed construction activities are
anticipated to be acceptable as indicated by predicted compliance with the
applicable WQOs. Impacts to benthic
assemblages immediately outside of the reclamationtemporary
working platform site and the cable laying area are expected to
occur temporarily and be confined to small areas. Based on the assumption that eventually these affected areas will
be recolonisied by fauna typical of the area, then the temporary indirect
disturbance to this low ecological value assemblage is deemed acceptable.
Subtidal Hard Surface
Habitats: Soft corals, gorgonians, hard corals and
anemones may be injured by both high suspended sediment concentrations and high
deposition rates. Damage (sublethal
effects) or mortality (lethal effects) can result from a reduction in light
penetration which kills the photosynthesizing symbiotic algae associated with
the hard corals, and also from the deposition of sediment onto the corals
surface which physically blocks the respiratory and feeding apparatus. An assessment of the effects of sand
dredging at West Po Toi (ERM 2001) assumed that prolonged turbidity and a
sustained sedimentation rate of 10 mg cm-2 day-1 (= 0.1
kg m-2 day-1) was damaging to corals. Negative impacts to corals may also arise
from increased SS in the water column. As water
quality perturbations resulting from the proposed Project works are predicted
to be minor and compliant with the WQO it is not anticipated that sediment
deposition rates
will exceed 0.1 kg m-2 day-1 along the
coast at Tai Long Wan.
Intertidal Habitats:
Intertidal habitats within the Study Area which may be affected by the
cable laying and reclamation activities and
formation of the temporary working
platform include the high ecological value mangrove and intertidal
mudflat at Pui O, the medium
ecological value intertidal rocky shore habitat, and the low ecological
value sandy shore at Tai Long Wan and gazetted beach at Pui O. Water
quality assessment results predict that unacceptable elevations of SS concentrations are
unlikely to occur. Consequently,
unacceptable impacts to these intertidal habitats are thus not anticipated.
Marine Mammals:
Mobile animals such as marine mammals have the ability to avoid areas where
SS levels have increased, thus avoiding any impacts. Impacts can occur to these mammals as an indirect result of
increased SS levels. The cable laying
activities and the reclamation workstemporary working platform
associated with the Project may cause perturbations to water quality which have
the potential to impact the fisheries resources of the South-east Lantau
area. The Indo-Pacific Humpbacked
Dolphin, Sousa chinensis, in Hong
Kong waters feed primarily on fish. The
dolphins are often seen associated with pair trawlers which are likely to
provide them with increased feeding opportunities; this appears to be confirmed
by the limited data available from stomach contents analyses. By examining the stomachs of 12 stranded
dolphins, Jefferson (1998) found that, with the exception of one individual’s
stomach content, which contained some squid remains, only fish had been
consumed. At least twenty species of
fish belonging to 13 families were found in the stomach of these stranded
dolphins. The most abundant families were anchovies - Engraulidae, croakers -
Sciaenidae, and sardines - Clupeidae accounting for more than 81% of all fish
in the stomachs of the stranded dolphins.
The Finless Porpoise, Neophocaena phocaenoides, is thought to be an opportunistic feeder
with known prey including crustaceans (shrimps and prawns), cephalopods (squid
and octopus) and small pelagic fish of low commercial value (anchovies,
croakers and sardines). They are thus
likely to be affected by any significant changes in key water quality
parameters arising from the project works.
A deterioration in water quality is likely to cause these mobile fish to
move out of the area thus interfering with the dolphin and porpoises normal
feeding patterns.
The water quality assessment undertaken for the
Project indicates that the construction activities are unlikely to adversely
affect the marine water quality within and in the vicinity of the Study
Area. In addition, the marine areas
within and in the vicinity of the Study Area show few sightings of marine
mammals and therefore the areas are not a critical habitat for the
animals. It is thus expected that
unacceptable impacts to the marine mammals arising from elevated SS levels will
not occur.
Dissolved
Oxygen
The relationships between SS and DO are
complex, with increased SS in the water column combining with a number of other
effects to reduce DO concentrations in the water column. Elevated SS (and turbidity) reduces light
penetration, lowers the rate of photosynthesis by phytoplankton (primary
productivity) and thus lowers the rate of oxygen production in the water
column. This has a particularly adverse effect on the eggs and larvae of fish,
as at these stages of development, high levels of oxygen in the water are
required for growth due to their high metabolic rate. Although respiratory responses and tolerance of hypoxia were
studied in two marine fish (Wu & Woo 1984), it is not possible to set
critical thresholds for this parameter for other marine organisms due to lack
of tolerance data for species in Hong Kong.
DO depletions are most likely to affect sessile organisms as they cannot
move away from areas where DO is low (unlike mobile species such as fish).
As the scale of
reclamation temporary working platform is very small
(0.055 ha180m2)
and the methodology used for cable laying are unlikely to severely affect water
quality, impacts resulting from depletions of DO as a result of the
construction activities associated with the proposed Project are unlikely to be
severe.
It is thus expected that unacceptable impacts to the marine
ecological resources present in the vicinity of the reclamation temporary working platform and the
cable laying operations arising from very small depletions in DO levels will
not occur.
Nutrients
High levels of nutrients (total inorganic
nitrogen - TIN and ammonia) 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
increases in DO levels in surface water.
However, at night and when these algae die there is usually a sharp
decrease in the levels of dissolved oxygen in the water as dead algae fall
through the water column and decompose on the bottom. Anoxic conditions may result if DO concentrations are already low
or are not replenished. This may result
in mortality to marine organisms due to oxygen deprivation.
Significant increases in nutrients in the
vicinity of the construction works areas are unlikely to occur and unacceptable
impacts to sensitive marine ecological habitats (mangrove and intertidal
mudflat at Pui O) as a result of nutrient increase are therefore not
expected. Due to the small-scale of reclamationtemporary
working platform and the transient and localised impacts resulting
from the cable laying activities, it is expected that unacceptable impacts to
the marine ecological habitats and populations present in the vicinity of the
works areas arising from very small elevations in nutrient levels will not
occur.
High and Low Frequency
Noise
As cetaceans are protected under the Wild Animals Protection Ordinance (Cap
170), 1980 any lethal and sublethal impacts due to underwater noise on marine
mammals will be deemed unacceptable.
Cetaceans are animals that rely heavily on acoustic information to
communicate and to explore their environment.
Therefore, any significant noise that disrupts communication or
echolocation channels would be potentially harmful.
Studies have shown that because of the
efficient transfer of sound in water, dolphins can detect noises associated
with vessels similar to dredgers at distances up to approximately 5 km
(Richardson et al. 1995). Noise
disturbance interferes with communication and echolocation pulses, which are
used for navigation and feeding, leading to behavioural changes. There is evidence suggesting that some
cetacean species will minimise their use of areas affected by underwater noise.
Most dolphins can hear within the range of 1 -
150 kHz though the peak for a variety of species is between 8 - 90 kHz
(Richardson et al. 1995). Dredging and
large vessel traffic generally results in mostly low frequency noise typically
in the range of 0.02 - 1 kHz which are below the peak range of 8 - 90 kHz
reported for dolphins and therefore, would not likely cause problems. As the marine waters in the vicinity of the
proposed works areas do not contain critical habitats for marine mammals, it is
thus anticipated that adverse underwater noise impacts will not occur.
Vessel
Traffic
Increases in marine traffic may disturb normal
cetacean movement patterns through potential collision with vessels, increased
turbidity generated by propellers and submerged equipment. Additionally, vessel
passes and noise can cause behavioural disturbance to these animals. This could affect both species. However, significant increases in vessel
traffic as a result of the construction activities associated with the Project
are unlikely and the habitat in the vicinity of the works areas is not a
critical habitat for marine mammals. It
is thus anticipated that unacceptable impacts to marine mammals as a result of
the slight increase in vessel traffic will not occur.
Assessment
of Environmental Impacts - Construction
The following section discusses and evaluates
the impacts to marine ecological habitats within the Study Area in the Adamasta
Channel between Chi Ma Wan Peninsula and Cheung Chau and at Pui O. From the information presented above the
marine ecological impact associated with the construction of the Project has
been evaluated in accordance with the EIA-TM
Annex 8 Table 1 as follows:
·
Habitat Quality: The reclamation workstemporary
working platform at Pui
O will result in the temporary loss of 0.055 ha180m2
of intertidal sandy shore. The cable
laying works to be undertaken in the Adamasta Channel will result in the permanent temporarypermanent loss
of 0.5 ha of soft bottom benthic habitat.
Although the sandy shore and soft bottom habitat
within the works areas will be permanentlypermanently
lost, these habitats are of low ecological value. High ecological value habitats (mangrove and intertidal mudflat
at Pui O) in the vicinity of the temporary working
platformreclamation site are not predicted to
be affected by the construction activities.
The marine areas within the Study Area are not critical habitats for the
Finless Porpoise and Indo-Pacific Humpbacked Dolphin and, therefore, the marine
mammals are unlikely to be affected by the proposed construction activities
associated with the Project.
·
Species:
No organisms
of ecological interest were recorded during the field surveys or reported from
the literature apart from the few colonies of the hard coral
species which
were recorded in low abundance but are commonly found in eastern
and western waters of Hong Kongfrom the subtidal hard
surface bottom near Tai Long Wan.
·
Size: The low
ecological value intertidal assemblages within the 0.055 ha 180m2
temporary working platform reclamation
site at Pui O and the subtidal soft benthic organisms within the
0.5 ha along the cable alignment in the Adamasta Channel will be directly lost but will be re-established. As will small areas (2 linear m) of rocky
intertidal and subtidal habitat at the cable landing points. Areas outside the work sites will experience
short term impacts due to water quality perturbations as a result of the reclamation
and submarine cable laying activities.
·
Duration:
Increases in SS levels in the vicinity of
sensitive receivers are expected to be low and temporary, and due to
constraints on reclamation and
submarine cable
laying operations, within environmentally acceptable limits (as defined by the
WQO's). Impacts to benthic and
intertidal assemblages in the submarine cable laying areas in the Adamasta
Channel will be permanenttemporary. Impacts to the intertidal assemblages at the Pui O
temporary reclamation site working
platform will occur
during construction but once the reclamation works area has been
removed the assemblages are expected to recolonise the area.
·
Reversibility:
Impacts to
subtidal and intertidal assemblages within the reclamation temporary working platformarea and
submarine cable laying sites are irreversible, whereas impacts to assemblages
outside of these works areas are expected to be transient and recolonization
should occur.
·
Magnitude:
The impacts
to the ecologically sensitive habitats outside of the works areas defined in
this review will be of low magnitude during construction of the Project. Impacts to assemblages within the reclamation temporary
working platformarea and
submarine cable laying sites are of low severity due to the small size of the
areas affected and the low ecological value of the habitat lost.
Operation Phase
Operational impacts to marine
ecological resources may occur through the following:
Hydrodynamic Regime
Impacts to
marine ecological resources could potentially occur if the shape of the
reclamation causes a change on the hydrodynamic regime of the Pui O
coastline. Impacts of this nature could
potentially lead to increased seabed current speeds which may cause seabed
scour thus impacting subtidal assemblages, or conversely the current speeds may
drop affecting flushing and water exchange of an area. Inadequate flushing could lead to reduction in
dissolved oxygen (DO) an increase in nutrients and consequent impacts to marine
ecological resources (DO and nutrient impacts are discussed above).
Given the shape and small size (1800.055 ham2) of the reclamation working
platform at Pui O (Figure
6.9) and the fact it is a temporary facility,
it is anticipated that impacts to tidal current speeds and directions will be minimalregligablenegligible.
Mitigation measures for the temporary changes to the
hydrodynamic regime are, therefore, not considered to be necessary.
Vessel Traffic
Increases in marine traffic may disturb normal
cetacean movement patterns through potential collision with vessels, increased
turbidity generated by propellers and submerged equipment. Additionally, vessel
passes and noise can cause behavioural disturbance to these animals. This could affect both species. However, significant increase in vessel
traffic during the operation phase is not expected as vessels for maintenance
and repair are unlikely to be frequent.
In addition, the marine area where the submarine cables will be laid is
not a critical habitat for marine mammals.
Therefore, it is anticipated that unacceptable operational impacts to
marine mammals as a result of increased traffic will not occur.
Assessment
of Environmental Impacts - Operation
The following section discusses and evaluates
the potential impacts to marine ecological habitats as a result of the
operation of the cable circuit in accordance with the EIA-TM Annex 8 Table 1 as follows:
·
Habitat Quality:
Operation of the proposed submarine cable circuit is not anticipated to
affect any ecologically sensitive habitats.
·
Species: No
organisms of ecological interest recorded during the field surveys or reported
from the literature that could potentially be impacted by operation of the
submarine cable circuit.
·
Size: The reclamationtemporary
working platform at Pui O is not expected to affect the
hydrodynamic regime of the immediate vicinity of the reclamationtemporary
working platform site. The impacts are anticipated to be minimal
and environmentally acceptable.
·
Duration: Vessels
for maintenance and repair will operate where necessary but their activities
are not expected to be frequent.
·
Reversibility: No
irreversible impacts from the operation of the submarine cable circuit are
predicted to occur.
·
Magnitude:
Impacts to
ecologically sensitive habitats in the vicinity of the cable circuit are not
predicted to occur during the operation phase.
6.4.5
Mitigation
Measures
Construction
Phase
The above assessment indicates that during
construction works the potential impacts to marine ecological assemblages are
environmentally acceptable and no marine ecology specific mitigation measures
are required. Constraints on
controlling impacts to water quality to within acceptable levels during
construction are expected to also control impacts to marine ecology. In accordance with the guidelines in the EIA-TM on marine ecology impact assessment the general policy for
mitigating impacts to marine ecological resources, in order of priority, are:
·
Avoidance:
Potential impacts should be avoided to the maximum extent practicable by
adopting suitable alternatives;
·
Minimisation:
Unavoidable impacts should be minimised by taking appropriate and
practicable measures such as constraints on intensity of works operations or
timing of works operations; and
·
Compensation:
The loss of important species and habitats may be provided for elsewhere
as compensation. Enhancement and other
conservation measures should always be considered whenever possible.
The previous discussion has indicated that the
following habitats within the Study Area will be lost:
·
Low
Ecological Value - 0.018 ha0.055 ha of intertidal shore at Pui O as
a result of provision of of reclamation forming the temporary working platform, andalbeit temporarily asbut this will be reinstated following
completion of excavation of the tunnel;
·
Low
Ecological Value - 0.5 ha of subtidal soft bottom benthos as a result of submarine cable layingproviding the
concrete indication layer over the cable.
This will be re-established by natural sedimentation over time;
·
Medium
Ecological Value - small narrow areas (2 linear m) of rocky shores as a result
of cable landing works.
The habitats to be lost due to the construction
activities associated with the proposed Project are small in area and of low or
medium ecological value. Given that
constraints on controlling impacts to water quality to within acceptable levels
during construction can control impacts on marine ecology, no mitigation
measures for marine ecological resources are required. It
is expected that over time rocky shore organisms will colonise the concrete
covered cable trough and similar communities will be re-established.
Operation
Phase
Impacts to marine ecological resources during
operation of the electric cable circuit are not predicted to occur. Hence no marine ecology specific mitigation
measures are required during Project operation.
6.4.6 Residual Impact
Taking into consideration the ecological value
of the habitats discussed in the previous sections and the resultant mitigation
requirements, residual impacts have been determined.
The residual impacts occurring as a result of
the proposed Project are as follows:
·
The temporary loss of 0.055 ha 180m2
natural intertidal sandy shore within the Pui O reclamation temporary worksing platform site. The residual impact is considered to be
acceptable as the area of habitat lost is small and the sandy shore is of low
ecological value and the effects temporary.
·
The
loss of 0.05 ha of the subtidal soft bottom
assemblages along the submarine cable alignment in Adamasta Channel. The residual impact is not considered to be
unacceptable as the habitat is of low ecological value.
·
The
loss of small areas (2 linear m) of rocky shore at the landing points. The residual impact is not considered to be
unacceptable as the area of habitat lost is small and the intertidal portion is
of moderate ecological value while the subtidal portion is of low ecological
value. Recolonisation of the concrete
cable troughs by intertidal and subtidal organisms may also occur over time.
6.4.7 Environmental Monitoring & Audit
Mitigation
measures to control impacts to water quality to within acceptable levels
during construction are expected to also control impacts on marine
ecology. No unacceptable impacts are
expected to occur during the operation phase of the Project. Hence, monitoring and auditing of marine
ecological resources during the construction and operation of the Project is
deemed not necessary.
6.4.8 Conclusion
Literature reviews of existing information
supplemented with the results of recently undertaken field surveys on marine
ecological resources indicate that the intertidal rocky shores within the Study
Area are of medium ecological value whereas for the sandy habitats, low
ecological value was assigned. Soft
bottom subtidal habitats identified in the review were regarded as of low
ecological value. A few isolated
colonies of hard and soft corals were recorded on the subtidal hard surface
habitats and were considered as of low ecological value. The waters near the proposed reclamationtemporary
working platform and submarine cable laying sites do not appear to
be highly utilised by marine mammals and it is considered that this area does
not contain critical habitat for the Indo-pacific Hump-backed dolphins and
Finless Porpoises.
Potential impacts to marine ecological
resources from the proposed construction works may arise either indirectly,
e.g. through perturbations of the surrounding water quality, or directly as a
result of habitat loss. A temporary loss of 180m2
total of 0.055 ha intertidal sandy
shore habitat, small areas of rocky shore and a permanent loss of 0.5
ha of subtidal soft bottom assemblages will be permanently lost
as a resulted of from the
construction activities associated with the Project. However, the assemblages to be lost are of low-medium ecological
value and given the small area to be directly affected, the impacts are
unlikely to be severe. Indirect impacts
during the construction process, such as an increase in SS levels and decrease
in DO in the water column may impact intertidal and subtidal filter feeders and
other marine organisms. However, the
effects are not expected to be severe and no unacceptable impacts are predicted
to occur.
Operational impacts to marine ecological
resources are not predicted to occur through disturbances to water quality due
to changes in the hydrodynamic regime of the area or an increase in marine
traffic for cable maintenance and repair.
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