8.1.1
This section of the Report identifies
and evaluates the nature and extent of potential impacts arising from the
Project, including reclamation for the proposed West Coast Road (WCR) and
construction of the cross bay bridge, on the marine ecological resources within
the Assessment Area.
8.1.2
The existing information on the marine
ecological resources contained in previous assessments on various Tsueng Kwan O
projects and other relevant reports and publications, has been reviewed in
order to identify ecological sensitive areas and to establish the baseline
ecological conditions of the Assessment Area. Where necessary, field visits
were undertaken to check ecological baseline conditions presented in the
literature. As stated in the TM EIAO,
the aim of ecological impact assessment is to protect, maintain or rehabilitate
the natural environment. Measures that are required to mitigate against
potential significant impacts are recommended, where appropriate.
8.2.1
This
Section makes reference to the following guidelines, standards, documents and
the HKSAR Government ordinances and regulations when identifying habitats and
species of ecological importance and evaluating ecological impacts:
·
Wild Animals
Protection Ordinance (Cap. 170);
·
Animals and Plants
(Protection of Endangered Species) Ordinance (Cap. 187)
·
Marine Parks
Ordinance (Cap. 476) and subsidiary legislation;
·
Town Planning
Ordinance (Cap. 131);
·
Sites of Special
Scientific Interest Register;
·
Hong Kong Planning
Standards and Guidelines (HKPSG) Chapter 10.
·
Environmental Impact
Assessment Ordinance (Cap. 499)
·
Technical Memorandum
on the Environmental Impact Assessment Process (EIAO-TM)
·
EIAO Guidance Note
Nos. 6/2002, 7/2002
8.2.2
Under
the Wild Animals Protection Ordinance (Cap. 170), designated wild animals are
protected from being hunted, whilst their nests and eggs are protected from
injury, destruction and removal. All
marine cetaceans and sea turtles are protected under this Ordinance. The Second
Schedule of the Ordinance, which lists all the animals protected, was last
revised in June 1992.
8.2.3
The
Animals and Plants (Protection of Endangered Species) Ordinance (Cap. 187)
provides protection for certain plant and animal species through controlling or
prohibiting trade in the species. Certain types of corals are listed in
Schedule 1 and 2 of the Ordinance, including Blue coral (Heliopora coerulea), Organ pipe corals (family
Tubiporidae), Black corals (order Antipatharia), Stony coral (order Scleractinia),
Fire corals (family Milleporidae) and Lace corals (family Stylasteridae). The
import, export and possession of scheduled corals, no matter dead or living, is
restricted.
8.2.4
The
Marine Parks Ordinance (Cap. 476) and Subsidiary Legislation allows for
designation, control and management of marine parks and marine reserves through
regulation of activities therein to protect, conserve and enhance the marine
environment for the purposes of nature conservation, education, scientific
research and recreation. The Ordinance came into effect on 1 June 1995. The
Authority administering marine parks and reserves is the Country and Marine
Parks Authority.
8.2.5
The
amended Town Planning Ordinance (Cap. 131) provides for the designation of
coastal protection areas, Sites of Special Scientific Interest (SSSIs),
Conservation Area, Country Park, Green Belt or other specified uses that
promote conservation or protection of the environment. The authority responsible for administering
the Town Planning Ordinance is the Town Planning Board.
8.2.6
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 describes
enforcement issues. The appendices list the legislation and administrative
controls for conservation, other conservation related measures in Hong Kong and
government departments involved in conservation.
8.2.7
Annex
16 of the TM-EIA sets out the general approach and methodology for assessment
of ecological impacts arising from a project or proposal, to allow a complete
and objective identification, prediction and evaluation of the potential
ecological impacts. Annex 8 recommends
the criteria that can be used for evaluating habitat and ecological impact.
8.2.8
EIAO
Guidance Note No. 6/2002 clarifies the requirements of ecological assessments
under the EIAO.
8.2.9
EIAO
Guidance Note No. 7/2002 provides general guidelines for conducting ecological
baseline surveys in order to fulfil requirements stipulated in the TM-EIA.
8.2.10 Furthermore, the assessment undertaken also makes reference to the
following international conventions and conservation treatises.
·
Convention on the Conservation of Migratory
Species of Wild Animals (the “Bonn Convention”)
·
United Nations Convention on Biodiversity
(1992);
·
The PRC National Protection List of Important
Wild Animals;
·
IUCN Red Data Books; and
·
Convention on the International Trade in
Endangered Species of Wild Fauna and Flora (CITES).
·
Key
Protected Wildlife Species List
8.2.11 Convention on the Conservation of Migratory Species of Wild Animals
(the Bonn Convention”) has two main objectives. These are a) to provide strict
protection for species listed in Appendix I of the Convention (migratory
species in danger of extinction throughout all or a significant portion of
their range), and b) to encourage Range States for such species to conclude
agreements for the conservation and management of Appendix II species
(migratory species which have an unfavourable conservation status and require
international agreements for their conservation, or which have a conservation
status which would significantly benefit from international co-operation). Hong
Kong was originally a Party to the Convention through the United Kingdom. The convention continues to apply to Hong
Kong after 1st July 1997 by agreement of the Sino-British Joint Liason Group,
though the PRC is not a party thereto.
8.2.12 The PRC are one of the Contracting Parties 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. Hong Kong
Government has stated it will be ‘committed to meeting the environmental
objectives’ of the Convention (PELB, 1996).
8.2.13 The IUCN Red List is the world’s most comprehensive inventory of the
global conservation status of plants and animals. It uses a set of criteria to evaluate the extinction risk of
thousands of species and subspecies.
These criteria are relevant to all species and all regions of the
world. There are seven Categories of
Threat in the IUCN Red List System: Extinct, Extinct in the Wild, Critically
Endangered, Endangered, Vulnerable, Near Threatened and Least Concern. A species is listed as threatened if it
falls in the Critically Endangered, Endangered or Vulnerable categories.
8.2.14 The Convention on International Trade in Endangered Species of Wild
Fauna and Flora (CITES) is a voluntary international agreement to ensure that
international trade in specimens of wild animals and plants does not threaten
their survival. PRC became a Party to the agreement in 1981.
8.2.15 The Key Protected Wildlife Species List details Category I and
Category II protected animal species under Mainland Chinese Legislation.
8.3.1
The ecological characteristics of the
Assessment Area were elucidated via a review of the literature. This review collated ecological information
from various reports and publications that included:
·
Oceanway (2003) Field Diving Surveys of Corals
for the Engineering and Feasibility Assessment Studies (EEFS) in relation to
the way forward for the Harbour Area Treatment Scheme (HATS) (with permission).
Submitted to EPD. (HATS Dive Survey Report)
·
CityU Professional Services (2003) Consultancy
Study on Marine Benthic Communities in Hong Kong. Final Summer Field Survey
Report. Submitted to AFCD.
·
Scott Wilson (2001) Tseung Kwan O Development
Phase III Road P2 connecting Town Centre and Western Coast Road Final EIA
Report (Road P2 EIA Report).
·
M2 Environmental (2000) Tseung Kwan
O Port Development at Area 131. Further Ecological Study. Submitted to TDD. (Area
131 Further Ecological Study Report)
·
Maunsell (2000) Feasibility Study for
Intensification and Extension of Tseung Kwan O New Town Final EIA Study (TKO
Extension EIA Report).
·
ERM (1999) Feasibility Study on the Alternative
Alignment for the Western Coast Road, Tseung Kwan O. (Western Coast Road EIA
Report).
·
Jefferson T (2000) Conservation Biology of the
Finless Porpoise (Neophocaena phocaenoides) in Hong Kong Waters: Final Report.
Ocean Park Conservation Foundation. Submitted to AFCD.
·
Report on Underwater Dive Surveys (October 1991
– November 1994) Volumes I & II (CED, 1995);
8.3.2
Field surveys were undertaken, where
appropriate, to supplement and check the validity of data collected through the
literature review process. Focused
surveys were conducted on the intertidal and subtidal habitats inside and in
proximity to the proposed reclamation area in the wet season from May to October
2004.
8.3.3
Potential ecological impacts arising
from the development were assessed following TM-EIA Annex 16 guidelines
and the impacts evaluated based on the criteria in TM-EIA Annex 8.
During the assessment, particular attention was paid to species of conservation
interest identified through literature review and field survey for this EIA
Study.
8.4.1
Junk
Bay (also known as Tseung Kwan O) is a south-facing bay located on the northern
side of the Tathong Channel at the southeast part of the New Territories. To the west, its waters connect to Victoria
Harbour through the narrow Lei Yue Mun Channel. To the south and south-east,
its waters open into the wider Tathong Channel, which either side is bounded by
the east coast of Hong Kong Island and the neighbouring coasts of the
Clearwater Bay Peninsula and Tung Lung Chau.
8.4.2
Although
facing the oceanic south-eastern waters of Hong Kong, in summer Junk Bay waters
are within reach of the seasonal influence of the massive discharges of water
from Pearl River, which extends from the west. In terms of hydrology, Junk Bay
is therefore regarded as being situated close to the eastern margins of a
transitional zone between Hong Kong’s oceanic eastern waters and the more
estuarine western waters (Morton & Morton 1983). Details on the baseline
water quality conditions in Junk Bay and adjoining channels are presented in Tables 5.5
and 5.6.
8.4.3
The
Assessment Area encompasses Junk Bay and a substantial area of the adjoining
coastal waters. The Assessment Area spans Victoria Harbour across Hong Kong’s
eastern and south-eastern coastal waters to include Clear Water Bay, the Nine
Pins island group, Sung Kong and Waglan Islands and the east coast of Hong Kong
Island to Cape d’Aguilar. This assessment area comprises several broad habitat
types including:
·
Intertidal habitats on hard substrata such as
natural rocky shore and artificial seawall.
·
Intertidal habitats on mobile soft substrata
such as sandy shore
·
Subtidal habitats including infaunal benthic
communities on soft substrata.
·
Subtidal habitats on hard substrata such as
coral communities.
·
Marine mammal habitat for the locally resident
cetacean, the Black Finless Porpoise .(Neophocaena
phocaenoides)
8.4.4
The baseline marine ecological
conditions of the assessment area are described in the sections below.
Locations of key marine ecological resources in the assessment area are shown
in Figure 8.1.
Areas
of Conservation Interest
8.4.5
Within
the assessment area, there are several marine areas of recognised or potential conservation
interest. The Cape d’ Aguilar (Hok
Tsui) Marine Reserve is located about 10km south of Junk Bay and comprises a
sea area of about 18 hectares. This reserve was established in July 1996 and
has been a designated SSSI since July 1990. It is also recognised as Hong
Kong’s only no-take Marine Protected Area (MPA). This area supports diverse
marine life including corals dominated by Platygyra sinensis, Favites abdita and Goniastrea
aspera (Clark
1997, 1998), as well as some subtidal macrofaunal assemblages that are unique
to the reserve (Morton & Harper 1997, Morton 1998, Morton 2003).
8.4.6
The
Shek O Headland SSSI is located about 8km south of Junk Bay. This exposed rocky
shore habitat was designated a SSSI in February 1998 because it is among the
areas with the richest assemblages of macroalgae (seaweed) in Hong Kong.
8.4.7
The
assessment area also extends as far as the coastal areas to the north of Clear
Water Bay approximately 8km from Junk Bay.
These shallow inshore waters to the north of Clear Water Bay support
corals and were previously identified as a possible marine park (The Marine
Parks and Reserves Working Group, 1990) or a potential Marine Conservation Area
(Planning Department 1998), mainly due to its existing use as a recreational
dive site (Morton 1998, Morton 2003).
Representative
Habitats
8.4.8
Representative
marine habitat of the assessment area is illustrated in Figure 8.2.
Baseline information giving the ecological profile of each habitat type within
the assessment area is provided below.
Rocky Shore
8.4.9
Within
Junk Bay, natural rocky shore habitat is located along the western side of the
bay extending from Chiu Keng Wan to Lei Yue Mun with a small stretch located
along the former Junk Island on the eastern side of the bay. In recent years,
natural rocky shore at the inner and east coast of Junk Bay has been almost
entirely lost to large-scale reclamation.
8.4.10
Elsewhere
within the Assessment Area, natural rocky shore habitat is located mainly
outside Victoria Harbour, fringing the east coast of Hong Kong Island and from
Joss House Bay around the coast to Clear Water Bay. Offshore islands such as
Tung Ping Chau, Waglan, Sung Kong and Nine Pins are also predominantly fringed
by natural rocky shores.
8.4.11
The
natural rocky shore at Chiu Keng Wan in the north west corner of Junk Bay was
previously surveyed in March and November 1997 with findings presented in the Western Coast Road EIA
Report. Both
qualitative and quantitative surveys were conducted. Qualitative surveys based on visual inspection covered approximately
500m of shoreline. Quantitative surveys used belt transects laid at 3
representative tidal heights with ten quadrats placed along each transect to
assess the abundance of intertidal flora and fauna.
8.4.12
It
was found that the assemblages comprised typical species of similar composition
and abundance to other semi-exposed rocky shores in Hong Kong. None of the species were rare and were
deemed to be of low conservation interest. Fauna found on the rocky shore at
Chiu Keng Wan were represented by 27 species comprising marine snails
(periwinkles: Nodolittorina
trochoides, Nodolittorina vidua, Nodolittorina radiata, Littoraria articulata,
Peasiella roepstorffina; whelks: Thais clavigera, Morula musiva; topshells: Chlorostoma
argyrostomas, Monodonta labio; turban shells: Lunella coronata; and nerites: Nerita albicilla), barnacles (Tetraclita squamosa, Capitelum
mitella),
limpets (Cellana
toreuma, Cellana grata, Patelloida
pygmaea, Patelloida saccharina), false limpets (Siphonaria japonica, Siphonaria sirrius, Siphonaria atra*), chitons (Acanthopleura japonica, Ischnochiton comptus), bivalves (mussels: Septifer virgatus; oysters: Saccostrea cucullata; and ark shells: Barbatia virescens), sea anemones (Anthopleura sp.) and rock crabs (Grapsus albolineatus).
8.4.13
Algal
cover on the rocky shore comprised erect coralline algae (Corallina sessilis), red encrusting algae (Peysonnelia sp.,
Hildenbrandtia prototypus), brown encrusting algae (Ralfsia expansa, Endopleura aurea, Hapalospongidion gelatinosum), green foliose algae (Ulva fasciata), brown turf algae (Hincksia mitchelliae), red turf algae (Gelidium pusillum, Gymnogongrus flabelliformis) and cyanobacteria (Kyrtuthrix maculans).
8.4.14
In
order to check and update information on the ecological profile of rocky shore
habitat at Chiu Keng Wan obtained from the literature review, ecological
surveys were conducted twice at the rocky shore during the 6-month field survey
period. Both qualitative and
quantitative surveys were undertaken in the wet season on 21st May and 19th
October 2004. Location of the surveys
is shown in Figure 8.3.
8.4.15
The
qualitative surveys involved visual reconnaissance along the entire Chiu Keng
Wan shoreline to record general site conditions and ecological features.
Quantitative information on representative rocky shore assemblages was obtained
by deploying standard line transects at low tide at two representative
locations on the rocky shore. The line transects were deployed perpendicular to
the shore to cover from the high water mark to low water. Along each transect,
standard ecological sampling quadrats (dimensions 0.5m x 0.5m) were laid at 1m
intervals. Intertidal flora and fauna were identified and enumerated. In
general, mobile fauna were counted to establish abundance per unit area. Abundance of sessile organisms such as
barnacles, oysters, algae and cyanobacteria were estimated in terms of
percentage cover per fixed area. All flora and fauna were identified to species
level as far as practicable.
8.4.16
Based
on reconnaissance observations, the natural rocky shore habitat was highly
comparable to conditions presented in the literature. The majority of the rocky
shore along the Chiu Keng Wan was similar in nature comprising southeast
facing, steeply sloping bedrock slabs and tuffs of volcanic origins, which extend
to a considerable height above intertidal levels. The rocky shore was generally steeper at the north of the Chiu
Keng Wan coast, which included a small stretch of vertical sea cliffs occurring
along at the rocky prominentry near to O King Road. In general, the rocky shore
at Chiu Keng Wan was formed by bedrock with little or no boulders. An exception
was the small stretches of small/medium-sized rocky boulders also occurred
adjacent to the middle cove and to a lesser extent adjacent to the seawall at the
north.
8.4.17
Rocky
shore fauna along the Chiu Keng Wan coast comprised species typical of other
semi-exposed rocky shores of eastern Hong Kong waters and followed typical
vertical zonation patterns mediated by tidal exposure. Qualitative surveys in
May and October 2004 revealed a similarly composed rocky shore community. On
the high shore, fauna was dominated by the periwinkles (Nodolittorina spp.), while seaslaters, Ligia exotica were also present but very infrequent along the coast. At the
mid-shore, assemblages were dominated by the limpet Cellana toreuma, and barnacles Tetraclita spp. and Common Top Shell Monodonata labio. On the low shore, rock oysters Saccostrea cucullata and mussels Sepifera virigatus dominated. Also occasionally
seen close to the water’s edge was the Common Rock Crab, Grapsus albolineatus.
8.4.18
More
detailed quantitative survey results of rocky shore assemblages at 2
representative locations on the Chiu Keng Wan coast are presented in Tables 8.1 and 8.2. Findings from the quantitative survey were highly similar to results
from previous surveys of this coast reported in the literature. The only
notable difference was the limited macroalgae found in the surveys for this EIA
Study, compared to previous survey findings. This was explained by the surveys
conducted in the hot summer months of the wet season, which are unsuitable for
macroalage to survive in the intertidal zone.
Table 8.1 Composition
and abundance (no. of individuals/ percentage cover per 0.25m2) of rocky shore
biota at Transect 1 at the Chiu Keng Wan coast on 19th May 2004 and 19th
October 2004.
Species /
Distance on transect
|
1m
|
2m
|
3m
|
4m
|
5m
|
6m
|
7m
|
1m
|
2m
|
3m
|
4m
|
5m
|
6m
|
7m
|
Survey date
|
19th May 2004
|
21st October
2004
|
Level
|
High------------------------------>Low
shore
|
High------------------------------>Low
shore
|
Snails
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Nodolittorina trochioides
|
96
|
15
|
|
|
|
|
|
69
|
5
|
|
|
|
|
|
Nodolittorina vidua & radiata
|
7
|
46
|
21
|
|
|
|
|
5
|
|
|
|
|
|
|
Monodonta labio
|
|
|
|
22
|
15
|
2
|
|
|
|
13
|
15
|
|
|
|
Lunella coronata
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Nerita albicilla
|
|
|
|
3
|
1
|
|
|
|
|
|
1
|
2
|
|
|
Nerita costata
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Peasiella sp.
|
|
|
|
|
|
|
|
|
|
|
1
|
|
|
|
Thais clavigera
|
|
|
|
|
1
|
1
|
|
|
|
|
|
1
|
1
|
|
Morula musiva
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Barnacles
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Tetraclita japonica
|
|
|
15
|
|
2
|
|
|
|
|
|
|
24
|
|
|
Tetraclita squamosa
|
|
|
|
|
|
1
|
13
|
|
|
|
|
|
|
19
|
Capitelum mitellum
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Chthalmus malayensis
|
|
2
|
|
|
|
|
|
|
|
|
|
|
|
|
Megabalanus volcano
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Limpets
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Cellana toreuma
|
|
|
|
55
|
|
137
|
|
|
|
|
4
|
|
35
|
5
|
Cellana grata
|
|
|
2
|
2
|
|
|
|
|
|
|
|
1
|
2
|
|
Siphonaria japonica
|
|
|
|
|
1
|
|
|
|
|
1
|
|
|
|
|
S. japonica egg coils
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Siphonaria laciniosa
|
|
|
|
|
|
|
|
|
|
|
|
|
|
11
|
Patelloida pygmaea
|
|
|
|
|
|
|
|
|
|
|
|
1
|
|
|
Patelloida saccharina
|
|
|
|
5
|
19
|
10
|
|
|
|
|
11
|
4
|
|
|
Bivalves
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Septifera virgatus
|
|
|
|
|
4%
|
5%
|
4%
|
|
|
|
|
|
|
|
Saccostrea cucullata
|
|
|
|
2%
|
5%
|
|
|
|
|
|
|
5%
|
10%
|
5%
|
Perna viridis
|
|
|
|
|
|
|
|
|
|
|
|
1%
|
|
5%
|
Barbatia virescens
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Chitons
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Acanthopleura japonica
|
|
|
|
|
|
|
|
|
|
|
1
|
|
1
|
1
|
Crabs
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Hemigrapsus sanguineus
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Sea anemones
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Spheractis chungae
|
|
|
|
|
|
|
7
|
|
|
|
1
|
1
|
|
|
Bristleworms
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Perinereis cultrifera
|
|
|
|
|
|
|
|
|
|
|
|
|
|
1
|
Tubeworms
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Hydroides sp.
|
33
|
|
|
|
|
|
39
|
|
|
|
|
|
|
|
Moquito larvae
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Culicidae sp.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Isopods
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Unidentified sp.
|
|
|
|
|
|
|
1
|
|
|
|
1
|
|
|
|
Algae
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Hildenbrandtia rubra
|
|
|
|
|
|
10%
|
80%
|
|
|
|
|
|
|
|
Ulva lactuca
|
|
|
|
5%
|
5%
|
8%
|
|
|
|
|
|
|
|
|
Ralfsia expansa
|
|
|
|
|
|
|
10%
|
|
|
|
|
|
|
|
Gellidium pusillum
|
|
|
|
|
|
|
2%
|
|
|
|
|
|
|
|
Pseudulvella applanata
|
|
|
|
|
|
|
|
|
|
|
|
|
|
3%
|
Lithophyllum sp.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
10%
|
T
Table 8.2 Composition
and abundance (no. of individuals/ percentage cover per 0.25m2) of
rocky shore biota at Transect 2 at the Chiu Keng Wan coast on 19th
May 2004 and 19th October 2004.
Species / Distance on
transect
|
1m
|
2m
|
3m
|
4m
|
5m
|
6m
|
1m
|
2m
|
3m
|
4m
|
5m
|
6m
|
7m
|
8m
|
Survey date
|
19th May 2004
|
21st October 2004
|
Level
|
High---------------------->Low shore
|
High------------------------------------>Low shore
|
Snails
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Nodolittorina trochioides
|
9
|
102
|
4
|
|
|
|
100
|
190
|
|
|
|
|
|
|
Nodolittorina vidua & radiata
|
2
|
6
|
40
|
|
|
|
1
|
30
|
|
|
|
|
|
|
Monodonta labio
|
|
|
|
5
|
11
|
|
|
24
|
19
|
5
|
|
4
|
|
|
Lunella coronata
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Nerita albicilla
|
|
|
|
|
1
|
|
|
|
|
3
|
|
|
|
|
Nerita costata
|
|
|
1
|
|
|
|
|
|
|
|
|
|
|
|
Peasiella sp.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Thais clavigera
|
|
|
|
|
1
|
1
|
|
|
21
|
5
|
4
|
3
|
11
|
4
|
Morula musiva
|
|
|
|
|
|
|
|
|
|
|
|
|
|
3
|
Barnacles
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Tetraclita japonica
|
|
2
|
7
|
|
7
|
6
|
|
|
1
|
|
|
41
|
30
|
|
Tetraclita squamosa
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Capitelum mitellum
|
|
|
|
|
|
|
|
|
|
2%
|
1%
|
|
|
|
Chthalmus malayensis
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Megabalanus volcano
|
|
|
|
|
1
|
|
|
|
|
|
|
|
|
|
Limpets
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Cellana toreuma
|
|
|
|
28
|
127
|
15
|
|
|
|
5
|
12
|
35
|
8
|
|
Cellana grata
|
|
|
|
8
|
|
|
|
|
1
|
|
|
6
|
|
|
Siphonaria japonica
|
|
|
|
1
|
7
|
3
|
|
|
|
1
|
|
|
|
|
S. japonica egg coils
|
|
|
|
|
3
|
|
|
|
|
|
|
|
|
|
Siphonaria laciniosa
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Patelloida pygmaea
|
|
|
|
|
|
|
|
|
|
|
2
|
3
|
|
|
Patelloida saccharina
|
|
|
|
2
|
4
|
|
|
|
|
|
4
|
18
|
|
|
Bivalves
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Septifera virgatus
|
|
|
|
8%
|
25%
|
3%
|
|
|
|
|
3%
|
2%
|
5%
|
5%
|
Saccostrea cucullata
|
|
|
|
15%
|
|
5%
|
|
|
|
|
|
4%
|
40%
|
60%
|
Perna viridis
|
|
|
|
|
|
|
|
|
|
|
|
|
5%
|
10%
|
Barbatia virescens
|
|
|
|
|
|
|
|
|
|
|
|
|
|
2%
|
Chitons
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Acanthopleura japonica
|
|
|
|
|
|
|
|
|
|
|
|
|
1
|
|
Crabs
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Hemigrapsus sanguineus
|
|
1
|
|
|
|
|
|
|
|
|
|
|
|
|
Sea anemones
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Spheractis chungae
|
|
|
|
|
2
|
|
|
|
|
|
|
|
|
|
Bristleworms
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Perinereis cultrifera
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Tubeworms
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Hydroides sp.
|
|
13
|
|
|
|
|
|
|
|
|
|
|
|
|
Moquito larvae
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Culicidae sp.
|
|
3
|
|
|
|
|
|
|
|
|
|
|
|
|
Isopods
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Unidentified sp.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Algae
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Hildenbrandtia rubra
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Ulva lactuca
|
|
|
|
|
5%
|
30%
|
|
|
|
|
|
|
|
|
Ralfsia expansa
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Gellidium pusillum
|
|
|
|
|
|
1%
|
|
|
|
|
|
|
|
|
Pseudulvella applanata
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Lithophyllum sp.
|
|
|
|
|
|
|
|
|
|
|
|
|
20%
|
20%
|
8.4.19
Although
the rocky shore harboured a similar species composition in May and October,
some differences in assemblages were noted particularly in terms of the lifestage
of organisms present. Assemblages of rocky shore fauna in May tended to reflect
to recent recruitment onto the rocky shore, which is indicative of a healthy
functioning community. For instance, during the May survey it was noted that
the limpet populations, particularly C. toreuma, generally comprised small individuals indicating their early
lifestage. Egg coils of Siphonaria japonica were occasionally observed.
Similarly, in May mussels Septifera virgatus, which were clustered in crevices on the low shore also tended to be
dominated by small individuals of an early lifestage.
8.4.20
Visual
survey over small stretches of boulder areas revealed these areas were
dominated by the snails Monodonata labio, Nerita
albicilla and Lunella coronata with many undersides of boulders
covered with tubeworms Hydroides sp. Small shore crabs such as Hemigrapsus sanginuineus, and Metagrapsus spp. were also common among the boulders. At
the low shore, the rock oyster Saccostrea cucullata was abundant, encrusted on many boulders. Other species, which were
infrequently recorded at low water were the Curly Murex Chicoreus microphyllus, Silver-mouthed Turban Turbo argyrostoma and cowrie Cypraea arabicus. At the northern end of the
shoreline near the seawall, a small patch of boulders was largely devoid of
intertidal biota. At this location, pebbles of dead hard coral rubble,
including of Cyphastrea, were noted to be accumulated
among the boulders.
8.4.21
Along
the Chiu Keng Wan coast, fish recorded in rock pools included the goby Bathygobius fusca and a single incidence of a
stranded Doublebar cardinalfish Apogon pseudotaeniatus. During the May survey, it was also noted that small open tidal
gullies along the low rocky shore provided shelter for dense schools of
unidentified fish fry. Small schools of fish fry as well as juvenile grey
mullet Mugil
cephalus were
also occasionally observed passing along the waters edge, whilst angler’s
catches were noted to include Rockfish, Sebasticus marmoratus, Russell’s snapper Lutjanus russellii, White-spotted Rabbit fish Siganus canaliculatus, Chinese damselfish Neopomacentrus bankieri, Japanese seaperch Lateolabrix japonicus and Red Drum Sciaenops ocellatus.
8.4.22
One
marine species of potential conservation interest was discovered at the rocky
shore habitat at Chiu Keng Wan. On May
21st 2004, a large rock pool up to 70cm deep located on the high
shore with a dense growth of Enteromorpha seaweed and sand/rubble/small boulder bottom substrata was found to
have 5 individuals of the Grassy Puffer fish (also known as the Starry or Snowy
Puffer), Takifugu
niphobles.
Several other dead individuals were found stranded on the high shore nearby.
8.4.23
Takifugu
niphobles is
listed as ‘data deficient’ in the IUCN red list of threatened species (Roberts
1996, UNEP/GEF 2003). Listing of taxa in this category indicates that more
information is required and acknowledges the possibility that future research
will show that threatened classification is appropriate. As an intertidal
spawner, Takifugu
niphobles
gathers at the waters edge at dusk at the full or new moon when tidal heights
are at their highest and strands in rock pools to spawn. Spawning is stimulated
by groups of 2-4 males that bite and hang on the side of single females as they
deposit eggs in sand and rubble at high tide. Individuals may remain stranded
in rock pools on the high shore, until they are freed by the next high tide
(Yamahira 1997a,b).
8.4.24
An ad hoc intensive search for this
species was conducted on 25th May 2004. The puffers observed a couple of days before were still stranded
in the same rock pool as previously found, though one was recently dead and
another lethargic presumably on account of the physiologically stressful
conditions associated with extremes of temperature and salinity in rock pools
in summer. During the survey, all rock
pools along the entire Chiu Keng Wan coast were searched. No other rock pools
with similar characteristics (i.e. dense macroalgae, deep with sandy boulder
bottom) were found. Other rock pools
tended to be shallow mid or low shore pools. No other stranded puffers were
found except a single small dead Milk-spotted puffer Chelonodon patoca in a crevice. Ad hoc observations on the presence of Takifugu niphobles were also noted during other
ecological survey visits to the coast in June, July, August and September. No
puffers were observed in rock pools in these months. During focused rocky shore
surveys conducted on 21st October, two individual Takifugu niphobles were found in the same large
rock pool.
8.4.25
Despite
its IUCN listing, T.niphobles has a widespread regional distribution, with records from throughout
the Pacific North-west region (including Japan, Korea, Taiwan, China, Hong Kong
and Vietman, Roberts, 1996). According to Sadovy & Cornish (2000), Takifugu niphobles “is moderately abundant in Hong
Kong and is known recently from several individuals along shallow boulder
shores, such as within the Cape d’Aguilar Marine Reserve”. Although it appears
not to be among species recorded during monitoring of artificial reefs (cf. Wilson 2003), this may be
because it generally occupies waters that are shallower than the depths at
which artificial reefs are deployed (Cornish pers. comm.). Other researchers (e.g. Yu & Yu 2002) have also
reported this species to be common in Hong Kong coastal waters.
Artificial Seawall
8.4.26 More than half of the shoreline within the Assessment Area comprises
artificial seawall habitat. Seawall forms virtually all of Victoria Harbour and
most of the Junk Bay shorelines. Assemblages of species present on artificial
seawalls, particularly sloping rubble mound seawall, which better mimics
natural conditions, may be expected to be similar to natural coasts. A study on
reestablishment of intertidal communities on the fringes of reclaimed land in
Hong Kong indicated it might take some eight to ten years for assemblages of
colonising intertidal organisms to reach peak complexity (i.e. a ‘climax’
community state) (Yip 1979). Given that seawalls in Junk Bay are relatively
new, it can be inferred that these seawalls support limited intertidal biota
and are of low ecological value.
8.4.27 Common ‘biofouling’ organisms previously recorded on artificial
seawalls and wharfs in Hong Kong include barnacles (Tetraclita squamosa,
Capitelum mitella and Balanus amphitrite), polychaete tube-worms (Hydroides
elegans, Spirobis foraminosus), mussels and oysters (Perna viridis,
Septifer virgatus, Saccostrea cucullata), bryozoans (Bugula neritina),
ascidians (Ascidia sydneiensis, Ciona intestinalis, Styela plicata) and
various macro-algae (Ulva fasciata, Entromorpha prolifera, Codium
cylindricum, Colpomenia sinuosa) (Morton & Morton 1983). Recent
results presented in the HATS Dive Survey Report for spotdives conducted close
to seawalls inside Victoria Harbour (e.g. off Kai Tak, Hung Hom and North
Point) in January 2003 recorded bryozoans (Schizoporella errata),
barnacles, mussels (Perna viridis) and sponges.
Sandy Shore
8.4.28 Within the Assessment Area, sandy shore habitats are relatively few.
In Junk Bay, remaining sandy shore habitats are restricted to a small number of
isolated coves along the remaining natural shores at the western edge of the
bay and Junk Island. There are also small stretches of sandy shore at Lei Yue
Mun Point, Joss House Bay and Tung Lung Chau. Elsewhere in the assessment area,
sandy shores most notably occur in the wave-exposed bays at Clearwater Bay and
at a few locations on the east coast of Hong Kong Island including Big Wave Bay
and Shek O. Sandy shores are mobile and unstable environments subjected to
constant water movement and wave action.
Few intertidal organisms are able to tolerate these conditions such that
sandy shores in Hong Kong may appear devoid of intertidal life (Morton &
Morton 1983, Morton et al. 1995).
8.4.29 Of the 3 small coves located in the north west corner of Junk Bay at
Chiu Keng Wan, two comprise sandy shore habitat, while the smaller northernmost
cove consists of a mixture of sand and small boulders. Following recent
large-scale reclamation, these are among the few remaining sandy shores in Junk
Bay. The sandy shores in these coves were previously surveyed in 1998 with
findings presented in the Road P2 EIA Report. Sand samples (0.5m2
by 0.25m deep) were collected and sieved at five points each along two
transects spanning the low to high shore in order to assess the abundance of
any macrofauna present such as burrowing bivalves. According to Road P2 EIA Report no macrofaunal
invertebrates (>500mm) were
present in the ten samples collected from the sandy shore at Chiu Keng Wan.
Nevertheless, a number of ghost crabs (Ocypode sp.) burrow openings were
found.
8.4.30
In order to provide up-to-date
baseline data, sandy shore surveys were conducted at low tide on 19th
May 2004 and 21st October 2004.
On each survey date, visual reconnaissance surveys were conducted along
the entire length of the sandy shores in the 2 sandy coves. In addition
quantitative surveys were conducted by deploying line transects perpendicular
to the shore at representative locations. At 2m intervals along the transects, a 0.5x 0.5m quadrat was sampled for
burrowing macrofauna to a depth of at least 30cm. Locations of the surveys are
shown in Figure 8.3.
8.4.31 Based on the surveys, it was considered that the same ecological
conditions persist and survey results from 1998 remain valid. No burrowing
macrofauna were found in the sand including in the swash zone on both survey
dates. It was also noted that observed shell debris on the shores were not of
sandy shore fauna. At Chiu Keng Wan, the factors contributing to the apparent
absence of burrowing macrofauna are likely to include water pollution and the
course grain size of sand on the beaches. Shin (in press) note that pollution
caused by anthropogenic activities is a possible source of low species
diversity on soft shore habitats. Eutrophication of sandy shore habitats at
Chiu Keng Wan was suggested by the presence of large numbers of pollution
tolerant polychaete tube-worms (Hydroides elegans) on the underside of
boulders found along the shores. Sandy shores with coarse grain size are
well-draining, which limits interstitial water retention leading to rapid
desiccation of the shore and hence intolerable conditions for sandy shore
infauna at the intertidal zone.
8.4.32 Nevertheless, reconnaissance surveys of the sandy shores revealed
there were numerous ghost crab burrows at high shore and above the strandline
among backshore vegetation (Ipomea
pes-caprae and Scaevola sericea).
A count of burrows on both survey dates revealed a sizeable population of ghost
crabs inhabiting these sandy shores with more than 150 large burrows found at
each of the sandy shores. As confirmed by ad
hoc observations during night surveys, burrows were made by the common
nocturnal Large Ghost Crab (Ocypode ceratophthalma).
8.4.33 Also of note, as previously reported, the sandy shores at Chiu Keng
Wan had little flotsam and other debris accumulated at the strandline and due
to their general inaccessibility exhibited few signs of disturbance from
recreational use. However discarded gillnets washed ashore were occasionally
observed.
8.4.34 Elsewhere in the assessment area, sandy shores with higher wave
exposure than Junk Bay were previously surveyed at Big Wave Bay and Shek O
beach by Wong (1990). Sampling
techniques involved collection of sand samples from the swash zone on the low
shore followed up by visual survey. These surveys were conducted monthly or
bi-monthly covering 14 months starting from April 1987. It was found that the
sandy shore faunal assemblages at these two locations were similar, though a
lack of ghost crabs at Shek O was attributed to human disturbance. Dominant
species were the surf clams Donax semigranosus and Donax cuneatus.
Other species recorded were mole crabs (Hippa pacifica), hermit crabs (Calcinus
herbstii), ghost crabs (Ocypode ceratophthalma), sand crabs (Matuta
lunata), mysid shrimps (Archaeomysis sp.), and the isopod (Excirolana
chiltoni) (Wong 1990). Although these data are relatively old, habitat
conditions at Big Wave Bay and Shek O have not changed substantially since the
surveys were conducted, and can therefore be considered broadly representative
of faunal assemblages currently residing in these areas.
Hard Substrata Subtidal Habitat
8.4.35 The assessment area encompasses a portion of Hong Kong eastern and
south-eastern coastal waters. Locally, these are among the waters that provide the
most sustaining conditions for coral growth and support many hard
(scleractinian) coral species (Morton & Morton 1983, Morton 1992, Ang
2002). Nevertheless, waters closer to urban areas including within Junk Bay are
subject to more pronounced pollution levels (refer to Chapter 5).
8.4.36 A large amount of information on the general distribution and
abundance of corals in the assessment area waters is available from the
literature. Dive surveys conducted for CED between 1991 and 1997 at numerous
locations across Hong Kong provided extensive information on coral species
distribution in the assessment area. According to these surveys (mainly using
qualitative techniques), the Assessment Area supports several shallow fringing
coral communities of high ecological value close to Clear Water Bay and along
the east coast of Tung Lung Chau. More recently, long stretches of coastline
within Junk Bay and the neighbouring Joss House Bay (Tai Mui Wan), Tung Lung
Chau and Ngan Wan (south of Cape Collinson) have also been surveyed for various
studies.
8.4.37 Coral information from the literature on the areas closest to
proposed development at Tseung Kwan O are presented in the following sections,
including at Chiu Keng Wan, which is the area that would be directly lost due
to the proposed WCR tunnel toll plaza reclamation.
Chiu Keng Wan (northwest Junk Bay)
8.4.38 Information on the ecological condition of subtidal habitats at Chiu
Keng Wan that may be subject to reclamation under the project are presented in
3 separate reports; namely the Road P2 EIA Report, the Area 131
Further Ecological Study Report and the HATS Dive Survey Report.
8.4.39 In October 1998, the first dive surveys were conducted along the
Chiu Keng Wan coastline with findings presented in the Road P2 EIA Report.
Survey techniques used included 8 general reconnaissance bounce dives lasting
up to 10 minutes and covering an area of 50-100m2 each. In addition, information on depth profiles
and marine life was collected along 6 transects extending from the shoreline up
to between 50m and 100m offshore to a depth of about –7mPD. Quantitative data
were also collected from a total of 120 60cm x 40cm photo-quadrats deployed at
about 2m intervals along two 100m transects positioned parallel to the shore at
–3mPD and –5mPD respectively. The placement of these two transects covered
stretches of rocky seabed identified as having among the highest abundance of
marine life of the entire survey area.
8.4.40 In total, the coral survey conducted for the Road P2 EIA Report
recorded the presence of 5 hard coral species at Chiu Keng Wan. Four of these hard coral species (Psammocora
haimeana, Alveopora sp., Favia speciosa, Montipora sp.) were small
and isolated colonies recorded from half a dozen locations during
reconnaissance dives. The other recorded hard coral species (Leptastrea
purpurea) was found inside one of the photoquadrats at –5mPD. These survey findings indicated that this
coast supported a very sparse cover and low species richness of hard corals.
8.4.41 According to the Road P2 EIA Report, the soft coral Dendonephthya
spp. was the most commonly occurring coral found. It occurred either in isolation or in small
groups of up to 5 to 6 colonies. Of the 120 photo quadrats recorded, Dendonephthya
occurred in 22 (i.e. 18%). In addition, gorgonian sea whips (Ellisella sp.)
and sea fans (Melithaea sp.) were also recorded and were more frequently
encountered in deeper water (below –6mPD) where the seabed turned from rocky
bedrock and boulders to silty mud. At shallower depths, the sea whip (Ellisella
sp.) was recorded in 3% of photo quadrats (i.e. present in 3 out of
120). Other subtidal marine life
recorded included sponges (Halichondria spp.), hydroids (Algaophenia
whiteleggei), burrowing anemones (Entacmea quadricolor, cf. Discosoma sp.)
and cucamarid sea cucumber (Colochirus crassus). A suspected octopus
midden containing broken crab carapaces was also encountered.
8.4.42 Coral data for this stretch of coastline is also available from Area
131 Further Ecological Study Report. Under this study, surveys were
conducted in February 1999 along 100m transects laid perpendicular to the
shore. A total of 5 such transects (i.e. Transects 10, 9, 8A, 8 and 7A) were
located inside the footprint of the proposed WCR reclamation. Within these
transects a patchy and sparse presence of faviid (mainly Favia speciosa)
gorgonians and soft corals were recorded. In the northernmost transect the
black coral Cirripathes sp. was also recorded in deeper waters.
Additionally, a further two 90m long horizontal transects were laid parallel to
the shore in shallow and deeper waters respectively. Along the 90m transect,
corals within 1.5m either side of the transect were recorded. No hard or soft
corals were found along these two transects. Only gorgonian seawhip and fans
were recorded. These numbered 15 colonies along the shallow water transect and
137 along the deeper water transect respectively.
8.4.43 Most recently, a spot dive of this area (labelled spotdive No. S033)
covering about 50m between depths of 1.5 to 10m was conducted in January 2003
with results presented in the HATS Dive Survey Report. The amount of
coral cover was determined to be very sparse (<1% cover). During the spot dive, 3 species of hard
coral were recorded. These were Platygyra sp., the ahermatypic Turbinaria
sp. and Leptastrea sp. In addition, two gorgonian coral species (Echinomuricea
sp. and Euplexaura sp.) were also recorded.
8.4.44 In summary, the literature review indicated that the subtidal
habitat at Chiu Keng Wan has been the subject of intensive survey effort in
recent years. In total, surveys have included eleven 50 or 100m transects laid
perpendicular to the shore, four 90-100m transects laid parallel to the shore
and 9 reconnaissance/ spot dives. Information from these recent surveys is
considered to provide adequate up-to-date and representative data reflecting
the ecological conditions of this area.
Based on these surveys, a total of 7 hard coral, 4 gorgonian, 1 soft and
1 black coral taxa were recorded. The literature indicated hard coral colonies
occurred as small isolated colonies and in very low abundance. In contrast,
soft corals and gorgonian seawhips frequently occurred but with a relatively
lower abundance compared to other neighbouring coastal areas.
Southwest coast of Junk Bay (south
of Chiu Keng Wan)
8.4.45 Information on the subtidal habitat along the coastline from the
south of Chiu Keng Wan to Lei Yue Mun is available from the Area 131 Further
Ecological Study Report and HATS Dive Survey Report. Although the
West Coast of Junk Bay is contiguous with Chiu Keng Wan coast, for assessment
convenience, the literature on this coastal stretch was reviewed separately. In
this way, literature review to establish the ecological profile of the
Southwest Coast of Junk Bay encompasses the area outside but immediately
adjacent to the proposed reclamation footprint.
8.4.46 Dive surveys for the Area 131 Further Ecological Study in
February 1999 were the first to investigate the subtidal habitat along west
coast of Junk Bay to the south of Chiu Keng Wan. Subtidal areas along this
coastal stretch were surveyed along thirteen 50m underwater transects laid
perpendicular to the shore at roughly regular intervals along the coast to Lei
Yue Mun (i.e. Transects 1, 1A, 2, 2A, 3, 3A, 4, 4A, 5, 5A, 6, 6A and 7).
Although survey along these transects indicated very low abundance of hard
coral (Tubastrea sp. and Faviids), it was found that an area at
the south of this coast close to Lei Yue Mun was notable for its high abundance
of soft and gorgonian corals (mainly Dendronephthya spp. and Euplexaura
curvata). This area of abundant
corals, which have colonised rubble dumped in a disused spoil ground in shallow
water about 100m offshore, covered an estimated 2.5 hectares. Some black corals
(Cirripathes sp.) were also recorded in this area. Two 90m long
transects were laid close to this area to count the number of coral colonies
present inside a 3m wide swathe of seabed.
In the transect laid in shallower water 15m from shore, 118 colonies of Dendronephthya
spp., 241 gorgonian colonies and 12 Faviid colonies were recorded. In the
deeper water transect laid a distance of 90m from shore, 337 colonies of Dendronephthya
spp. and 328 gorgonians were recorded.
8.4.47 More recently, the southwest coast of Junk Bay was surveyed again
with results presented in the HATS Dive Survey Report. In January 2003,
a reconnaissance dive (labelled spot dive S034) was conducted covering a
distance of approximately 350m between the depths of 5.7m to 11.5m. From this
survey, coral cover was estimated at >20% but affected by relatively high
(30%) partial mortality. Species recorded were ahermatypic hard corals
including Tubastrea sp. as well as gorgonian corals (Echinomuricea sp.,
Menella sp., Guaiagorgia sp. and Euplexaura sp.). Following
reconnaissance dives, this area was selected for survey using Rapid Ecological
Assessment (REA) methods. This technique deployed transects to assess coral
composition and relative abundance across 200m2 of sea bed in three
different depth zones (shallow:-2 –5mCD; middle: -7 – 9mCD; deep: -12 –
15mCD). This REA survey (labelled REA
7) indicated soft and gorgonian corals were especially prevalent in the middle
and deep depth zones (25-50% cover in middle and deep zones, <10% in
shallow) with a few hard corals confined to the shallows (<5% cover). Seven species of gorgonian and soft corals
were recorded. These were Echinomuricea
sp., Euplexaura sp., Dendronephthya sp., Echinogorgia sp.,
Anthogorgia sp., Menella sp. and sea fans. The few hard corals present comprised a total of 8 hard coral
species. These were Goniopora
stuchburyi, Cyphastrea sp., Cyphastrea seralia, Favites pentagona,
Oulastrea crispata and Turbinaria peltata as well as the ahermatypic
Tubastrea sp. and Dendrophyllia sp.
8.4.48 In summary, the literature, derived from recent surveys conducted in
1999 and 2003, provides extensive information on the ecological profile of the
subtidal coastal fringes of the Southwest Coast of Junk Bay. Based on the
literature, the southwest coast of Junk Bay supports a very low cover of hard
corals with a total of 8 species recorded (including 2 ahermatypic species).
Coral assemblages mostly comprise soft and gorgonian corals dominated by the
seawhip Echinomuricea sp. These soft and gorgonian corals were common
along the coast and formed an area with high abundance at the south-west end of
the bay. Black coral (Cirripathes sp.)
was also recorded from this area.
Junk Island
8.4.49 Junk Island (also known as Fat Tong Chau) is located on the eastern
side of Junk Bay and has been partially engulfed by reclaimed land. Its remaining natural subtidal area was
investigated in underwater dive surveys conducted in 1999 and 2003 with
findings presented in the Area 131 Further Ecological Study Report and
the HATS Dive Survey Report respectively.
8.4.50 In early February 1999, a total of four qualitative reconnaissance
dives were conducted within 100m of the shoreline on the west coast of Junk
Island. According to the Area 131 Further Ecological Study Report, this
area supported small Faviid hard corals, some colonies of Tubastrea sp.,
soft corals (Dendronephthya sp.) and gorgonians but with lower
abundance as compared to the southwest coast of Junk Bay.
8.4.51 In January 2003, this area was surveyed again with findings
presented in the HATS Dive Survey Report. Initially, two reconnaissance spot
dives (labelled S030 and S031) were conducted between 2.7m and 13.3m depth and
covered a total distance of approximately 350m. Results indicate 2 hard coral
species (Porites sp. and Cyphastrea sp.) and 5 gorgonian
taxa (Echinomuricea sp., Menella sp., Guaiagorgia sp.,
Euplexaura sp. and Echinogorgia sp.) were present. Coral
cover observed during these two dives was estimated to be >10% (with partial
mortality of 10%) and >20% (with partial mortality of 15%)
respectively. Further information on
this area was then gathered using Rapid Ecological Assessment (REA) methods.
This technique deployed transects to assess coral composition and relative
abundance across 200m2 of sea bed in three different depth zones
(shallow:-2 –5mCD; middle: -7 – 9mCD; deep: -12 – 15mCD). With the exception of one colony of Acanthastrea
echinata in the shallows, no hard corals were recorded during the dive
survey (labelled REA 6). In contrast, soft corals and gorgonians were
relatively abundant (shallow: 10-25% cover; middle: 25-50% cover; deep: <5%
cover) represented by Echinomuricea sp., Euplexaura sp.,
Anthogorgia sp., Dendronephthya sp., Menella sp. and Echinogorgia
sp..
8.4.52 In summary, recent surveys at Junk Island in 1999 and 2003 indicated
that this coastal stretch harboured very few hard corals in terms of abundance
and the number of species present. Nevertheless, soft corals and gorgonians
were frequent and occurred in moderate abundance.
Tathong Channel
8.4.53 To the south/southeast of Junk Bay, waters open into the Tathong
Channel. The coastal fringes on the
north and south sides of the Tathong Channel were previously surveyed in 2003
at Ngan Wan (east coast of Hong Kong Island), Joss House Bay and Tung Lung
Chau. These areas neighbouring Junk Bay also support the growth of corals and
were recently investigated by the HATS coral dive surveys in 2003.
8.4.54 Of the coastal stretches bordering the Tathong Channel, these recent
surveys indicated the richest coral communities occurred at East Joss House
Bay, North Tung Lung Chau and Ngan Wan.
At East Joss House Bay, there was 10 – 25% cover of hard corals confined
to shallow areas with a total of 23 species coral recorded. Platygyra acuta
was the most common hard coral at this site. In contrast, there was relatively
little soft / gorgonian coral at this location (<5% cover). Similar hard coral cover (10-25%) occurred
in the shallows off North Tung Lung Chau, though fewer hard coral species were
present. Of the 7 hard coral species recorded, Favites dominated. In
deeper waters off North Tung Lung Chau, soft / gorgonian corals were scattered
and sparse (<5% cover). In contrast, at Ngan Wan, surveys discovered a rich
and diverse soft / gorgonian coral community extending from the shallows into
deeper waters and dominated by Echinomuricea sp.. In the shallows, the
seafan, seawhips and soft corals were markedly larger than middle and deep
depths and occurred with 25-50%. In
middle and deep depths, soft/ gorgonian coral cover was 10 - 50%. In addition,
7 species of hard coral occurred in the shallows but with sparse cover
(<5%). Goniopora stuchburyi
was the most frequently occurring hard coral at this location.
8.4.55 Other areas surveyed along the fringes of the Tathong Channel in
2003 at West Joss House Bay and South Tung Lung had relatively low coral
abundance and diversity. Rapid
ecological assessment survey of West Joss House Bay revealed sparse hard coral
cover of <5%. Eight species of hard
coral were recorded in the shallows of which Cyphastrea seralia was most
abundant. Soft /gorgonian coral was virtually absent from this location. Similarly, according to findings of the HATS
coral dive surveys, South Tung Lung Chau supported low cover (<5%) of hard
corals represented by 4 species as well as low soft /gorgonian corals (<5%).
Dive survey of Chiu Keng Wan
8.4.56 Based on the review of the literature above, it was considered there
was extensive and recent information on most of Junk Bay for assessment
purposes. However, in comparison with adjacent coast of Junk Bay’s west coast,
there was relatively less information available for the Chiu Keng Wan coast,
which would be totally lost under the proposed WCR reclamation. In light of this, it was decided further
ecological surveys within the footprint of the proposed WCR reclamation area
were needed. The dive surveys of this coast under this EIA Study were conducted
to supplement and verify findings obtained from the literature review and to
obtain up-to-date information on baseline conditions of this coast. In this
way, the dive survey was conducted to cover subtidal habitat along the 800m
stretch of coastline inside the proposed WCR tunnel toll plaza reclamation
area, as well as a 100m section of coastline to the south of the proposed
reclamation.
8.4.57 The methodology used in the dive survey was discussed with AFCD and
involved reconnaissance dives as well as Rapid Ecological Assessment (DeVantier
et al., 1998) survey of 20 representative transects. Furthermore,
information on the size, growth form, health and substratum association of hard
corals was recorded. The dive surveys were conducted in 4 days (1st,
6th, 9th and 10th September 2004). Details on the methodology, location,
results and discussion are provided in Appendix 8.1.
8.4.58 Reconnaissance dives were conducted to identify the extent of hard
substrate with an emphasis on gaining an overview of coral occurrence within
and adjacent to the proposed reclamation area.
Figure 3.1 of Appendix 8.1 shows the areas covered by the reconnaissance dives, while Figure 3.2 of Appendix 8.1 shows an underwater habitat
map based on underwater dive observations.
8.4.59 As illustrated in Figure 3.2 of Appendix 8.1 (habitat map), the substrata in the proposed reclamation area
closely matched shoreline features by comprising mainly sandy areas fringing
the small sandy coves and with hard substrata bedrock extending between 20m to
70m off shore from rocky shore areas and from 8m to 12m deep. In deeper waters offshore, the seabed
consisted of mud and silt. The
reconnaissance dives covered areas from approximately –3mCD to –14mCD. Cross
sections of the seabed features and substrata composition at 4 representative
intervals along the Chiu Keng Wan coast are shown in Appendix 8.1.
8.4.60 Reconnaissance dive observations revealed that most of the Chiu Keng
Wan coast supported a low cover (in general about 1% cover) of octocorals (soft
coral, seawhips and seafans) and a sparse cover (<1% cover) of hard corals.
At the south of the dive survey area at the margin of the southern most edge of
the proposed reclamation area it was estimated that patches of octocoral reached
up to about 10% cover.
8.4.61 Coral cover (in addition to other biota) was further quantified
using Rapid Ecological Assessment techniques along a total of 20
representative, 100 m long x 2 m wide belt transects laid at intervals along
and parallel to the shore were deployed in 3 different depth ranges (shallow,
middle, deep). Figure 3.4 of Appendix 8.1 shows the locations where the REA transects were deployed. Table 8.3 provides a
summary of REA survey findings.
Table 8.3 Summary
of Rapid Ecological Assessment dive survey results.
|
|
South <
-------------------------------------------------------------------------------------------------------------
> North
|
Shallow
|
Transect
|
T01
|
T03
|
T06
|
T07
|
T10
|
T11
|
T14
|
T15
|
T18
|
Substratum
type
|
Bedrock & boulder
|
Bedrock & rubble
|
Sand
|
Bedrock & boulder
|
Sand
|
Bedrock
|
Bedrock & boulder
|
Bedrock & boulder
|
Bedrock & boulder
|
Hard coral
cover (%)
|
<1
|
<1
|
0
|
0
|
0
|
<1
|
<1
|
<1
|
<1
|
Octocoral
cover (%)
|
5
|
10
|
<1
|
0
|
0
|
2-3
|
<1
|
<1
|
0
|
Middle
|
Transect
|
T02
|
T04
|
|
T08
|
|
T12
|
|
T16
|
T19
|
Substratum
type
|
Bedrock & boulder
|
Bedrock, boulder & sand
|
|
Sand
|
|
Bedrock, boulder & sand
|
|
Sand
|
Sand & rubbles
|
Hard coral
cover (%)
|
0
|
0
|
|
0
|
|
<1
|
|
0
|
0
|
Octocoral
cover (%)
|
15
|
10-15
|
|
0
|
|
6-10
|
|
0
|
0
|
Deep
|
Transect
|
|
T05
|
|
T09
|
|
T13
|
|
T17
|
T20
|
Substratum
type
|
|
Mud
|
|
Mud
|
|
Mud
|
|
Mud
|
Mud
|
Hard coral
cover (%)
|
|
0
|
|
0
|
|
0
|
|
0
|
0
|
Octocoral
cover (%)
|
|
0
|
|
0
|
|
0
|
|
0
|
0
|
8.4.62 Findings of the REA survey found hard coral cover was sparse along
the entire Chiu Keng Wan coast in all depth zones. Hard coral cover did not reach higher than 1% cover in any of the
twenty transects. Hard corals were typically small, of encrusting growth form
and attached to bedrock. In all, surveys identified 8 species of hard coral
from the Chiu Keng Wan coast. Species
recorded in the dive surveys were Goniopora stutchburyi, Plestiastrea
versipora, Psammocora superficialis, Oulastrea crispata, Favites pentagona,
Favia cf. favus, Turbinaria peltata and the ahermatypic Tubastrea sp.
8.4.63 The cover of octocoral was also generally low, ranging from 0% to
15% cover. The highest soft coral cover
of 10 – 15% was found at the south the Chiu Keng Wan coast with another area of
octocoral with 5-10% cover found about midway along the Chiu Keng Wan
coast. Overall, the surveys revealed
that the Chiu Keng Wan coast supported 2 soft corals and 4 gorgonian seawhip /
seafan corals. Soft corals were Dendronephthya sp. and Cladiella sp. The gorgonians were Echinomuricea sp,
Menella sp., Euplexaura sp. and Echinogorgia sp. No
black corals were found during the surveys.
8.4.64 These findings were similar to information obtained from literature
review (see sections 8.4.24 to 8.4.30) and indicate that the Chiu Keng Wan
coast supports a sparse cover of hard corals of species that are common and
widespread across Hong Kong as well as patches of low to moderate cover of
common and widespread soft and gorgonian corals.
8.4.65 A summary of the coral species recorded in Junk Bay is provided in Table 8.4.
Table 8.4 Summary
Information on Coral Species recorded in Junk Bay
Coral Species
|
Chiu Keng Wan* (i.e. proposed reclamation area)
|
Southwest coast of Junk Bay*
|
Junk Island*
|
Chiu Keng Wan (i.e. proposed reclamation area) and adjacent 100m stretch of southwest coast of Junk Bay**
|
Hard Coral
|
|
|
|
|
Achanthastrea
echinata
|
|
|
+
|
|
Alveopora sp.
|
+
|
|
|
|
Cyphastrea
seralia
|
|
+
|
|
|
Cyphastrea sp.
|
|
+
|
+
|
|
Favia
speciosa /
'Faviids'
|
+
|
+
|
+
|
|
Favites
pentagona
|
|
+
|
|
+
|
Goniopora
stuchburyi
|
|
+
|
|
+
|
Leptastrea
purpurea / sp.
|
+
|
|
|
|
Montipora sp.
|
+
|
|
|
|
Oulastrea
crispata
|
|
+
|
|
+
|
Platygyra sp.
|
+
|
|
|
|
Plesiastrea
versipora
|
|
|
|
+
|
Porites sp.
|
|
|
+
|
|
Psammocora
haimeana
|
+
|
|
|
|
Psammocora
superficialis
|
|
|
|
+
|
Turbinaria
peltata
|
|
+
|
|
+
|
Turbinaria sp.
|
+
|
|
|
|
Hard coral (Ahermatypic)
|
|
|
|
|
Dendrophyllia
sp.
|
|
+
|
|
|
Tubastrea
sp.
|
|
+
|
+
|
+
|
Soft Corals
|
|
|
|
|
Dendronephthya
spp.
|
+
|
+
|
+
|
+
|
Cladiella sp.
|
|
|
|
+
|
Gorgonian seawhips/ seafans
|
|
|
|
|
Anthogorgia sp.
|
|
+
|
+
|
|
Echinogorgia sp.
|
|
+
|
+
|
+
|
Echinomuricea sp.
|
+
|
+
|
+
|
+
|
Ellisella sp.
|
+
|
|
|
|
Euplexaura sp.
|
+
|
+
|
+
|
+
|
Guaiagorgia sp.
|
|
|
+
|
|
Melithaea sp.
|
+
|
|
|
|
Menella sp.
|
|
+
|
+
|
+
|
‘sea fans’
|
|
+
|
|
|
Black
coral
|
|
|
|
|
Cirripathes sp.
|
+
|
+
|
|
|
Number
of species recorded
|
|
|
|
|
Hard coral
|
7
|
9
|
4
|
7
|
Soft coral
|
1
|
1
|
1
|
2
|
Gorgonians
|
4
|
7
|
6
|
4
|
Black coral
|
1
|
1
|
0
|
0
|
*Information collated from Road
P2 EIA Report (1998), Area 131 Further Ecological Study Report
(1999) and HATS Dive Survey Report
(2003)
**Dive survey results of
this EIA study
Soft Substrata Benthic Habitat
8.4.66 The most recent information available from the literature on the
benthic infauna of Junk Bay is provided in Study on Marine Benthic
Communities in Hong Kong Report. As part of this territory-wide study
commissioned by AFCD, 5 replicate 0.1m2 grab samples were collected
from a depth of 14m at a sampling station (Station 85) located in the middle of
Junk Bay in July 2001. Results showed that this habitat supported a low
abundance of benthic infauna recorded at 114 benthic animals m2 with
biomass (wet wt.) of 1.62 g m2. The benthos was characterised as
moderately disturbed (W Statistic value = 0.051). Of the 23 species recorded,
none were deemed to be rare or of conservation interest.
8.4.67 According to the Study on Marine Benthic Communities in Hong Kong
Report, the benthos at Station 85 in the middle of Junk Bay was dominated
by polychaete worms in terms of numerical abundance (84.2%) and biomass
(79.0%). Moreover, 17 of the 23 species recorded at the sampling station were
polychaetes. Polychaetes recorded in
Junk Bay were Ophlina acuminata, Agaeophalmus dibranchis, Mediomastus sp., Glyceridae
sp., Sigambra hanaokai, Sigambra sp., Paraprionospio pinnata, Prionispio
malmgreni, Syllinae sp., Tharyx marioni, Mediomastus
californiensis, Sthenolepis japonica, Notomastus latericeus, Marphysa depressa,
Aglaophamus lyrochaeta, Heteromastus sp. and Heteromastus
filiformis. Of these, Mediomastus sp. was the most
numerically abundant with 21% of all animals recorded belonging to this
species. However this species comprised only 11% of the assemblage’s biomass.
Therefore in terms of biomass, Aglaophamus dibranchis was the most
abundant species since it contributed about a fifth (22%) of the assemblage’s
biomass but with lower numerical abundance (14%). The remainder of the benthic
animals recorded in Junk Bay comprised nemertean ribbonworms (Procephalathrix
arenarius, Cerebratulus dervelli and Lineus binigrilinearis),
bivalves (Tapes literata and Tellina cygnus) and ghost shrimps (Callianassa
japonica).
8.4.68 In order to further characterise the infaunal benthos in the
Assessment Area, a benthic grab survey was conducted along the north west coast
of Junk Bay (Chiu Keng Wan), focused on the soft substrata seabed area inside
the proposed reclamation area. This survey was conducted on 1st September 2004
(wet season). Five replicate grab samples from a total of three representative
survey stations were collected using a Van Veen grab sampler with a gape of
0.1m2 (dimension of 15cm
wide, 32cm long and biting depth of 16cm).
The location of the survey stations is presented in Figure 8.3. This map shows sample stations labelled ‘Station 1’, ‘Station 2’
and ‘Station 3’ roughly evenly spaced along the Chiu Keng Wan coast.
8.4.69 Standard methods were employed to handle the samples. Each grab
sample was sieved immediately on landing on board the survey vessel so that
material > 0.5 mm was retained. This
material was stained and preserved using rose bengal solution for examination
and sorting in the laboratory. Infauna
present in the samples were identified to the lowest taxonomic level
practicable, enumerated and biomass (wet weight) measured. Analysis of the
ecological attributes of benthic assemblages from each of the stations was conducted
to include calculation of diversity (H’), evenness (J) and disturbance status
(W). A summary of key findings and benthic community attributes are presented
in Table 8.5. Detailed findings of the
benthic survey are presented in Appendix 8.2.
Table 8.5 Summary
of benthic survey results.
Attribute
|
Station 1*
|
Station 2*
|
Station 3*
|
Overall
|
Physical
|
|
|
|
|
Location
|
22°17°840’ N
114°15°346’E
|
22°17°727’ N
114°15°242’ E
|
22°17°645’ N
114°15°161’ E
|
-
|
Depth
|
8.1m
|
9.2m
|
10.2m
|
-
|
Sediment type
|
Silty mud / shell debris/ sand / gravel
|
Silty mud / shell debris
|
Silty mud / shell debris
|
-
|
Abundance
|
|
|
|
|
No of individuals
Actinaria
Nemertea
Polychaeta
Sipunculida
Mollusca
Crustacea
Phoronida
Echinodermata
Chordata
|
230
-
2.61%
69.93%
4.35%
-
22.59%
-
0.43%
-
|
188
0.53%
0.53%
93.58%
2.66%
-
1.59%
1.06%
-
-
|
187
-
0.53%
88.75%
-
5.35%
4.27%
0.53%
-
0.53%
|
605
0.17%
1.32%
83.14%
2.48%
1.65%
10.41%
0.50%
0.17%
0.17%
|
Biomass (wet wt.)
Actinaria
Nemertea
Polychaeta
Sipunculida
Mollusca
Crustacea
Phoronida
Echinodermata
Chordata
|
1.14g
-
4.42%
58.77%
3.54%
-
23.89%
-
8.85%
-
|
1.00g
1.00%
1.00%
81.00%
3.00%
-
12.00%
2.00%
-
-
|
1.69g
-
0.59%
38.46%
-
21.89%
32.54%
0.59%
-
5.92%
|
3.83g
0.26%
1.83%
55.76%
1.83%
9.69%
24.61%
0.79%
2.61%
2.61%
|
Density
|
|
|
|
|
Density of individuals
|
460 individuals/ m2
|
376 individuals/ m2
|
374 individuals/ m2
|
404 individuals/ m2 (average)
|
Density of biomass
|
2.28 g/m2
|
2.00 g/m2
|
3.38 g/m2
|
2.55 g/m2 (average)
|
Community
|
|
|
|
|
Species richness
|
34 species
|
30 species
|
29 species
|
51 species
|
Diversity (H’)
|
2.69
|
2.41
|
2.37
|
2.49 (average)
|
Evenness (J)
|
0.76
|
0.71
|
0.71
|
0.73 (average)
|
Disturbance
|
|
|
|
|
W statistic
|
-0.175
|
-0.211
|
-0.059
|
-0.148 (average)
|
8.4.70 The collected sediment at the three survey stations was of a similar
composition and was retrieved from similar depths. Sediment in each replicate
from Stations 1, 2, and 3 was composed of silty mud with some shell debris. At
Station 1 it was noted that a higher fraction of the bottom mud consisted of
coarse sand with some gravel. The depth
at Stations 1, 2, and 3 was 8.1m, 9.2m and 10.2m respectively.
8.4.71 In total, more than 600 infaunal individuals were enumerated from
the grab survey as a whole. Overall,
the benthos was numerically dominated by the polychaetes (83.1%). The remaining portion comprised crustaceans
(10.4%), sipunculids (2.5%), molluscs (1.7%), nermerteans (1.3%), phoronids
(0.5%), echinoderms (0.2%), actinians (0.2%) and chordates (0.2%). A summary of
the species composition and numerical abundance of the surveyed benthos is
presented in Table 8.6.
Table 8.6 Composition
and abundance of the soft substrata benthic community in grab samples collected
from Chiu Keng Wan, Junk Bay on 1 September 2004.
Group
|
Species
|
Survey Station
|
1
|
2
|
3
|
Total
|
ACTINIARIA
(sea anemones)
|
Actiniarian sp.
|
-
|
1
|
-
|
1
|
NEMERTEA
(ribbonworms)
|
Nemertean sp.
|
6
|
1
|
1
|
8
|
POLYCHEATA
(bristleworms)
|
Aglaophamus dibranchis
|
-
|
1
|
2
|
3
|
Aglaophamus lyrochaeta
|
1
|
2
|
2
|
5
|
Amphicteis sp.
|
1
|
-
|
-
|
1
|
Aonides oxycephala
|
1
|
-
|
-
|
1
|
Armandia leptocirrus
|
-
|
1
|
-
|
1
|
Chaetozone setosa
|
7
|
5
|
-
|
12
|
Euclymene natalensis
|
-
|
1
|
-
|
1
|
Eunice indica
|
2
|
-
|
-
|
2
|
Euniphysa aculeata
|
-
|
1
|
-
|
1
|
Glycera rouxi
|
1
|
-
|
-
|
1
|
Glycera tridactyla
|
1
|
2
|
1
|
4
|
Glycinde kameruniana
|
51
|
33
|
21
|
105
|
Laonice cirrata
|
-
|
1
|
-
|
1
|
Leocrates chinensis
|
-
|
1
|
1
|
2
|
Leonnates persica
|
6
|
-
|
-
|
6
|
Lumbrineris nagae
|
-
|
1
|
-
|
1
|
Lumbrineris sp.
|
3
|
2
|
2
|
7
|
Magelona crenulifrons
|
2
|
3
|
1
|
6
|
Mediomastus californiensis
|
10
|
2
|
6
|
18
|
Minuspio cirrifera
|
1
|
-
|
2
|
3
|
Nephtys polybranchia
|
19
|
12
|
9
|
40
|
Nereis guangdongensis
|
1
|
-
|
-
|
1
|
Notomastus latericeus
|
2
|
-
|
-
|
2
|
Ophelina grandis
|
1
|
-
|
2
|
3
|
Paraleiocapitella sp.
|
-
|
-
|
3
|
3
|
Paraprionospio pinnata
|
3
|
6
|
10
|
19
|
Pectinaria papillosa
|
1
|
-
|
-
|
1
|
Phyllodoce malmgreni
|
3
|
4
|
1
|
8
|
Poecilochaetus serpens
|
7
|
-
|
1
|
8
|
Prionospio ehlersi
|
2
|
7
|
15
|
24
|
Prionospio malmgreni
|
18
|
10
|
6
|
34
|
Pseudopolydora kempi
|
9
|
68
|
75
|
152
|
Sigambra hanaokai
|
3
|
6
|
2
|
11
|
Sternaspis scutata
|
1
|
1
|
-
|
2
|
Terebellides stroemi
|
-
|
1
|
-
|
1
|
Tharyx marioni
|
4
|
5
|
4
|
13
|
SIPUNCULIDA
(Peanutworms)
|
Apionsoma sp.
|
10
|
5
|
-
|
15
|
MOLLUSCA
(clams, snails etc.)
|
Gafrarium sp.
|
-
|
-
|
2
|
2
|
Marcia sp.
|
-
|
-
|
2
|
2
|
Bivalve sp. 1.
|
-
|
-
|
6
|
6
|
CRUSTACEA
(isopods, amphipods, crabs and shrimps etc.)
|
Gnathia sp.
|
1
|
-
|
-
|
1
|
Amphipod sp.1
|
47
|
2
|
-
|
49
|
Amphipod sp.2
|
1
|
-
|
-
|
1
|
Amphipod sp.3
|
-
|
-
|
1
|
1
|
Unidentified shrimp
|
-
|
-
|
1
|
1
|
Typhlocarcinus nudus
|
3
|
1
|
6
|
10
|
PHORONIDA
(tubeworms)
|
Phoronis australis
|
-
|
2
|
1
|
3
|
ECHINODERMATA
(urchins, starfish, sea cucumbers etc.)
|
Holothurian sp.
|
1
|
-
|
-
|
1
|
CHORDATA
(vertebrates e.g. fish)
|
Odontamblyopus rubicundus
|
-
|
-
|
1
|
1
|
8.4.72 The polychaetes were the dominant benthic group, represented by a
total of 36 species from 22 families.
Overall, the Spionidae and Goniadidae were the most represented
polychaete families in terms of numerical abundance. These accounted for 46.5%
and 20.9% of all polychaetes identified respectively. Of the remaining
polychaete families, other relatively well-represented families were the
Nephtyidae (7.9%), Cirratulidae (5.0%), Capitellidae (4.6%) and Pilargiidae
(2.2%).
8.4.73 The most numerically abundant species from any group in the benthic
survey was also a polychaete being Pseudopolydora kempi. Approximately 25% of all benthic animals
found were identified as belonging to this species. Another polychaete, which
dominated the benthos in terms of numerical abundance, was Glycinde
kameruniana. Overall, this species
comprised 17.4% of all benthic animals found in samples.
8.4.74 Apart from being enumerated, benthic animals were also weighed to
determine their biomass. In terms of
biomass, the polychaetes were also the dominant component of benthos. Polychaetes
accounted for more than half (55.8%) of
the total biomass of the survey’s benthos as a whole. In the same way,
crustaceans accounted for about a quarter (24.6%) of the biomass. This
crustacean biomass was mainly contributed by the crab, Typhlocarcinus nudus,
which was also the survey’s dominant species in terms of biomass. It accounted
for 21% of the total biomass despite its overall low numerical abundance of
only 10 individuals. Of the
polychaetes, Glycinde kameruniana was the dominant species in terms of
its biomass. It contributed 5.7% of the
total overall biomass. Other polychaete
species with relatively high abundance in terms of biomass were Euclymene
natalensis (5.3%) and Glycera tridactyla (5.3%). The most numerically abundant species, the
polychaete Pseudopolydora kempi ranked as the fourth most abundant
polychaete in terms of its biomass. Its
contribution was 3.7% of the total.
Overall, the biomass of the benthos off Chiu Keng Wan was considered to
be low (2.55g/m2) compared to benthic communities examined from
elsewhere in Hong Kong.
8.4.75 Aside from aiding description of the ecological profile of the
subtidal benthic community, biomass information combined with numerical
abundance data is also useful to characterise the disturbance status of a
benthic community. For each of the grab
stations, an abundance biomass comparison was conducted which may be used to
infer the extent to which benthos are affected by environmental disturbance
such as organic pollution (Clarke 1990). Abundance biomass comparison plots
(ABC plots), together with W statistic, for each sample station are illustrated
in Appendix 8.2. The W statistic measures
the extent the biomass curve lies above the numerical abundance curve. In
general, positive values indicate ‘undisturbed’, while negative values indicate
‘disturbed’ conditions. Calculation of the W Statistic indicated that all
stations were characterised as ‘disturbed’. W Statistic for Stations 1, 2 and 3
were -0.175, -0.211 and -0.059
respectively.
8.4.76 In total, 51 species of benthic fauna were found in the samples. In
terms of diversity, the sampled benthic community off Chiu Keng Wan was
considered to be of moderate diversity (average H’ = 2.49) in comparison to
other benthic communities in Hong Kong.
8.4.77 In summary, survey results indicated that the soft substrata seabed
off Chiu Keng Wan supported a disturbed benthic community of moderate diversity
and of low abundance. No species of conservation interest were identified.
Marine Mammal Habitat
8.4.78 While there are two resident cetacean species in Hong Kong, the home
range of only one, the Finless Porpoise (Neophocaena phocaenoides)
coincides with the Assessment Area. In
the IUCN Red Data Book, the Finless Porpoise is listed as ‘data deficient’
meaning that based on current understanding, it is not certain whether the
species is threatened (Reeves et al. 1997). Nevertheless local populations elsewhere in China are considered
‘endangered’ and this species is probably the most intensively exploited marine
cetacean in China (Reeves et al. 1997).
The Finless Porpoise is listed under Appendix 1 of the Convention on
International Trade in Endangered Species of Wild Fauna and Flora. Locally, this species is considered to be of
high conservation interest.
8.4.79 The Finless Porpoise is a shy and difficult to see animal but is
known to occur over much of Hong Kong coastal waters (Morton et al.
1995). The
most detailed knowledge of the local Finless Porpoise population’s distribution
and abundance has been acquired through sightings data collected during line
transect surveys by the Ocean Park Conservation Foundation (OPCF) from late
1995 to late 2000 and since that time by AFCD. Finless porpoise sightings occur
across the southern and eastern waters of Hong Kong from South Lantau to Mirs
Bay. Southern waters off South Lantau. Lamma and Po Toi (and neighbouring
Aizhou waters outside Hong Kong) are particularly important habitat for finless
porpoises although there are seasonal differences in their use. For instance,
porpoises appear to vacate South Lantau waters in summer and autumn. In eastern
waters such as off Nine Pins, the Sai Kung peninsula and Mirs Bay, Finless
Porpoise sightings occur in offshore areas throughout the year. In contrast,
inshore areas in Hong Kong eastern waters such as portions of Port Shelter, the
Tolo inlet, Double Haven and Crooked Harbour did not appear to be used by
finless porpoises.
8.4.80 Based on the 1995-2000 surveys, which were conducted in Hong Kong as
well as adjacent Guangdong (Aizhou) waters, Jefferson (2000) estimated that the
finless porpoise population was at least 217 animals. Inside Hong Kong waters, the estimated number of animals was
calculated to vary from a peak of 152 animals in spring to 55 animals in
autumn.
8.4.81 Eight years’ records (1996 - 2004) of Finless Porpoise sightings
recorded by Jefferson (2000) and by recent AFCD monitoring are presented in Figure 8.4. This indicates there are no records of finless porpoise sightings
in Junk Bay or immediately adjacent waters. The nearest isolated sighting of a
live finless porpoise to Junk Bay was recorded about 2km south of Tung Lung
Chau in 1997 (AFCD). In addition, inspection of stranding records collected
from 1996-2004 of finless porpoises also revealed no animals had been
discovered washed ashore in Junk Bay, which provides further evidence on their
absence from this area. In contrast, confirmed reports of strandings of dead
finless porpoises were in other parts of the assessment area at Shek O (10
strandings, 1996-2000, AFCD), Clearwater Bay (10 strandings, 1996-2004, AFCD),
Cape d’Aguilar (2 strandings, 1997 & 1999, AFCD), Big Wave Bay (1
stranding, 2004, AFCD), Nine Pins (1 stranding, 2000, AFCD) and Po Toi (1
stranding, 2000, AFCD).
8.4.82 Based on the available records, waters within and adjacent to Junk
Bay do not appear to be utilised by Finless Porpoises and are considered not
important for this species.
8.5.1
In accordance with the EIAO TM Annex 8
criteria, the ecological importance of recorded habitats has been evaluated in Tables 8.7a to 8.7c below.
Table 8.7a Ecological Value of natural rocky shore and artificial seawall
habitats
Criteria
|
Natural Rocky Shore
|
Artificial Seawall
|
Naturalness
|
The rocky shore is largely
undisturbed by human activity.
|
Artificial, constructed
habitat.
|
Size
|
Large in extent.
|
Large in extent and the
most predominant intertidal habitat of the Assessment Area
|
Diversity
|
Typical of other
semi-exposed shores in eastern Hong Kong
|
Low
|
Rarity
|
One species of conservation
interest recorded – Grassy Puffer fish (Takifugu niphobles) is
catalogued in the IUCN red list of threatened species
|
Species assemblages similar
to rocky shore. No records of species of conservation interest
|
Re-creatability
|
Habitat is
re-creatable. Intertidal biota may
recolonise hard substrata shores
|
N/A
|
Fragmentation
|
Very low.
|
N/A
|
Ecological linkage
|
The habitat is not
functionally linked to any high value habitat in a significant way.
|
The habitat is not
functionally linked to any high value habitat in a significant way.
|
Potential value
|
Low
|
None identified.
|
Nursery ground
|
One Rock pool on rocky
shore is apparently used for spawning by Takifugu niphobles. However
this species is widespread in Hong
Kong waters, and breeding populations in Junk Bay are not thought to be of
particular conservation significance.
|
No significant records.
|
Age
|
N/A
|
Seawalls of Junk Bay were
recently constructed and are generally <10 years old.
|
Abundance/Richness of Wildlife
|
Moderate. Typical species of similar
composition and abundance as other semi-exposed rocky shores in Hong Kong.
|
Low
|
Ecological value
|
Low-Moderate.
|
Low.
|
Table 8.7b Ecological Value of sandy shore habitat and hard substrata
subtidal habitat
Criteria
|
Sandy Shore
|
Hard Substrata Subtidal
Habitat
|
Naturalness
|
The small semi-exposed
sandy shores at Chiu Keng Wan are relatively free from physical modifications
and disturbance from recreational use, but are affected by water pollution to
some extent.
|
Coral habitats are largely
natural. Corals in Junk Bay may be
affected by water pollution to some extent.
|
Size
|
3 small coves in Junk Bay.
2 sandy shores span 75m and 80m of coastline respectively. Sandy/boulder
shore spans 50m.
|
Medium in extent. Corals
are restricted to shallow hard substrate and attain moderate or high cover at
a restricted number of sites in the Assessment Area. Chiu Keng Wan supports
low cover of hard and soft corals.
|
Diversity
|
Very Low.
|
Low.
|
Rarity
|
No species of conservation
interest recorded. Sandy Shores in the Assessment Area support faunal
assemblages with low species diversity.
|
No species recorded in
surveys were considered rare. Species
recorded are found in similar habitats across Hong Kong.
|
Re-creatability
|
Habitat is re-creatable
|
Corals may recolonise
subtidal hard substrata
|
Fragmentation
|
Moderate-High. Sandy shores form a small portion of
intertidal habitat in the Assessment Area.
|
Low.
|
Ecological linkage
|
The habitat is not
functionally linked to any high value habitat in a significant way.
|
The habitat is not
functionally linked to any high value habitat in a significant way.
|
Potential value
|
Moderate.
|
Coasts with corals are of
conservation interest.
~2.5 ha area of high
gorgonian and soft coral cover at the southwest corner of Junk Bay was
noteworthy in the context of its close proximity to Victoria Harbour.
|
Nursery ground
|
No significant records.
|
No significant records
|
Age
|
N/A
|
N/A
|
Abundance/Richness of Wildlife
|
Very low diversity but
sizeable ghost crab populations
|
Sparse presence of hard
corals and low to moderate abundance of common gorgonians and soft corals in
Junk Bay.
|
Ecological value
|
Low – Moderate.
|
The Assessment Area
supports numerous coral communities of high
or medium ecological value
predominantly near Clearwater Bay, Sung Kong, Nine Pins, Joss House Bay, Tung
Lung Chau and Ngan Wan.
Corals at the proposed reclamation
area (i.e., Chiu Keng Wan) comprise small, isolated colonies in very low
abundance and diversity
Chiu Keng Wan – Low
West Coast of Junk Bay – Moderate
Junk Island – Moderate
|
Table 8.7c Ecological Value of soft substrata subtidal and marine mammal
habitats
Criteria
|
Soft Substrata Subtidal
|
Marine Mammal
|
Naturalness
|
Habitat disturbed by
pollution, fisheries and coastal development
|
Some disturbance through
vessel traffic and commercial fishing operations.
|
Size
|
Large.
|
Small. The known range of Neophocaena phocaenoides only overlaps
the southern and eastern margin of the Assessment Area.
|
Diversity
|
Moderate species diversity
dominated by polychaetes.
|
Finless Porpoise (Neophocaena phocanoides) is the only
resident cetacean of the assessment area waters.
|
Rarity
|
No species of conservation
interest recorded
|
IUCN
listed N. phocanoides is a species of
conservation importance.
|
Re-creatability
|
Benthic organisms may
recolonise disturbed seabed areas
|
This habitat cannot be
recreated.
|
Fragmentation
|
The habitat is not
fragmented.
|
Marine mammal habitat is
not fragmented
|
Ecological linkage
|
The habitat is not
functionally linked to any high value habitat in a significant way.
|
Sightings of the Finless
Porpoise are more frequent to the south and east of the Assessment Area.
|
Potential value
|
Low. It is unlikely that
soft subtrata habitat will develop conservation value.
|
Monitoring records indicate
no Finless Porpoise have been sighted within or in the immediate vicinity of
Junk Bay.
|
Nursery ground
|
No significant record.
|
No strandings of N. phocanoides have been recorded from
Junk Bay
|
Age
|
N/A
|
N/A
|
Abundance/Richness of Wildlife
|
Benthic infauna recorded in
low abundance.
|
Low
|
Ecological value
|
Low.
|
Low.
|
8.5.2
Based on the ecological conditions
presented in the above sections, the ecological value of marine habitats in the
assessment area was considered to be as follows.
8.5.3
Artificial seawall was considered to
be of low ecological value given that it is the most extensive intertidal
habitat type in the Assessment Area and supports common and widespread biota
with no significant species records.
8.5.4
Rocky shore is a common habitat, which
was largely natural, undisturbed and extensive in size in the Assessment Area.
It supported common and widespread species typical of semi-exposed shores in
Hong Kong. This intertidal habitat was found to be utilised as a spawning site
by a species of potential conservation interest Takifugu niphobles,
although only one small rock pool along the whole of the coastline was used by
this species, which is relatively common in Hong Kong waters. Overall, rocky
shore habitat was considered to be of low-moderate ecological value.
8.5.5
Sandy shore habitats along the coast
at Chiu Keng Wan are considered of low-moderate ecological value only. Although
these habitats were observed to be relatively free from physical modification
and disturbance from recreational use, they were also noted to be small in
size, and compared to other sandy shore habitats (e.g., Big Wave Bay and Shek O
Beaches, section 8.4.34 refers), supported faunal assemblages with extremely
low diversity. As noted in section 8.4.31, factors contributing to the low
faunal diversity of these shores are likely to include water pollution and
course grain size of the sand on the beach.
8.5.6
Soft substratum subtidal habitat
supported low abundance of common and widespread species dominated by the
polychaetes. This habitat was
considered to be of low ecological value
8.5.7
Owing to the sparse and patchy cover
of hard and soft corals and the small size of hard corals which comprised
species commonly found in coral areas elsewhere in Hong Kong, hard substrata
subtidal habitat at Chiu Keng Wan inside Junk Bay were considered to be of low
ecological value. Elsewhere in Junk
Bay, the west coast of Junk Bay (to the south of Chiu Keng Wan) and Junk Island
(Fat Tong Chau) were considered to be of moderate ecological value.
8.5.8
Since records of live sightings of
Finless Porpoises only occur at the southeast margin of the Assessment Area not
within Junk Bay, it was considered that these marine waters were of low
ecological value as marine mammal habitat.
8.5.9
In accordance with the TM-EIA Annex 8
criteria, the species of conservation interest are evaluated in Table 8.8 below.
Table 8.8 Species of Conservation Interest within
Assessment Area
Common Name
|
Scientific
Name
|
Status*
|
Protection Status
|
Distribution, Rarity and Other
Notes
|
Fauna
|
|
|
|
|
Grassy (also known as Starry) Puffer fish
|
Takifugu niphobles
|
DD
|
Not protected
|
Reported to be moderately
abundant in Hong Kong. Intertidal
spawner.
|
Black Finless Porpoise
|
Neophocaena phocaenoides
|
DD
|
Wild Animals Protection
Ordinance Grade I Protected Species in the PRC. CITES Appendix 1
|
Range from South Lantau
waters to Mirs Bay and adjacent PRC waters. Peak abundance in HK waters is
about 150 animals in spring.
|
Coral communities
|
-
|
-
|
Some taxa protected under
Cap. (187)
|
Corals found in various
marine habitats in Hong Kong waters, particularly in northern and
north-eastern waters.
|
* CR
– Critically Endangered (Best available evidence indicates it is facing an
extremely high risk of extinction in the wild); EN – Endangered (Best available
evidence indicates it is facing a very high risk of extinction in the wild); VU
– Vulnerable (Best available evidence indicates it is facing a high risk of
extinction in the wild); NT – Near Threatened (It is close to or likely to
qualify for a threatened category in the near future) LC – Least Concern (It
does not qualify for threatened or near threatened categories); DD – Data
deficient (No assessment of extinction risk can be made but it should receive
same degree of attention as taxa in threatened categories). Refer to IUCN Red
List Categories and Criteria (version 3.1) (2001) for further details.
8.6.1
The scope and extent of the Project
works are described in detail in Section 2 of this Report. Potential marine
ecological impacts resulting from construction and operation phase activities
have been identified, and are outlined in the following sections.
Construction
Phase
Direct Impacts
8.6.2
Potential direct impacts on marine
ecology arising from the proposed construction activities would include:
·
Loss of approximately 1km of largely natural
intertidal rocky shore and 0.2km of sandy shore habitat due to WCR reclamation
·
Loss of approximately 0.25km of artificial
seawall habitat due to WCR reclamation
·
Loss of seabed affecting approximately 16.3ha
of soft and hard substrata subtidal habitats due to WCR reclamation
·
Loss of approximately 0.2ha soft substrata
subtidal habitat due to construction of piers for the Cross Bay Link.
Indirect Impacts
8.6.3
Potential indirect construction phase
impacts would include:
·
water quality impacts on coral areas due to
dredging for WCR reclamation and potential disturbance impacts to marine
mammal habitat due to increased vessel traffic and construction activities.
These potential impacts are discussed in more detail in the following sections.
Water Quality Impacts – Suspended Sediments
8.6.4
Possible indirect impact on subtidal
habitat may arise due to water quality deterioration, and particularly due to
siltation effects during the marine works.
Hard corals are known to be at particular risk of deleterious impacts
from sedimentation through smothering and clogging of their respiratory and
feeding apparatus. Similarly, more turbid water may reduce the amount of light
reaching beneath the water surface, which may also be detrimental to hard
corals. With less light, growth rates of hermatypic hard corals (coral which
possesses photosynthetic algae called zooanthellae) may be reduced. The effects
of increased sediment levels in the water column also extend to other marine
groups apart from the corals. For instance, fauna inhabiting soft substrate may
also be smothered if sedimentation rates are high.
8.6.5
Hard corals possess mechanisms for
rejecting sediment from their surfaces, but employment of these mechanisms
expend energy and may cause stress ultimately leading to bleaching (expulsion
of zooxanthellae) or tissue necrosis.
The vulnerability of different corals to sedimentation effects is not
the same. Hard corals with horizontal
plate-like or massive growth forms are more vulnerable than hard corals that
grow with plates arranged vertically or with upright branches. Hard corals with convex surfaces or
possessing tall polyps are also less sensitive. Sensitivity to sediment loading also varies markedly between
species of the same genus (Hawker and Connell 1992) and may even vary between
individual colonies of the same species as individual colonies change their
growth form to best cope with different sedimentation regimes where they live
(Pastorok and Bilyard 1985).
8.6.6
In contrast, soft and gorgonian corals
are considered to have greater tolerance of turbid conditions. Owing to their
flexible branches and erect growth forms, it is known that soft and gorgonian
corals are not prone to sediment accumulation. Furthermore, gorgonian and most
soft corals feed independently without contributions from algal associates and
are therefore not affected by light reduction due to increased turbidity.
8.6.7
Since potential impacts on corals may
arise through increased turbidity (i.e. elevation in SS) and excessive sediment
deposition, the magnitude of impacts on corals was assessed based on both of
these water quality parameters.
8.6.8
To assess the impacts associated with
elevated SS, the assessment was based on compliance with the statutory Water
Quality Objectives (WQO) for Junk Bay Water Control Zone (see Table 5.2), which
are set for among other reasons, to offer protection for marine ecological
resources. Water quality modelling predictions were assessed for compliance
with the WQO through comparison of worst case scenario’s 15-day depth-averaged
SS level against baseline levels. Using
this criterion, if the elevation in SS levels exceeds 30% above ambient
baseline conditions, adverse impacts would be predicted (and suitable
mitigation pursued).
8.6.9
There are no WQOs regarding
sedimentation rates. To assess impacts on corals due to sediment deposition,
criteria were adopted that were derived from research work by Pastorok and
Bilyard (1985). These leading
authorities on sedimentation effects, published criteria that suggested impact
levels on corals would occur as follows:
· 10
– 100 g m-2 per day slight
to moderate impacts
· 100
– 500 g m-2 per day moderate
to severe impacts
· >500
g m-2 per day severe
to catastrophic impacts
8.6.10 With reference to the above criteria, the sedimentation rate of not
exceeding 100 mg cm-2 per day (or 0.1 kg m-2 per day)
which has been adopted in previous EIAs([1]) in Hong Kong, is also considered as
suitable for use in this study.
8.6.11 This sedimentation rate criterion was considered to offer sufficient
protection to corals and is anticipated to guard against unacceptable impacts.
This protection has been confirmed by EM&A programmes, which have indicated
no adverse impacts to corals have occurred when this assessment criterion was
adopted.
Water Quality Impacts – Dissolved oxygen
8.6.12 Apart from sedimentation effects, corals in particular may also be
sensitive to changes in other water quality parameters during the construction
phase. As bottom sediment is disturbed
during dredging and particles released into the water column, organic
substances contained in the sediment may be oxidised or fed upon by microbial
life. These processes use up some of
the oxygen in the water. If oxygen
levels are depleted to low levels, benthic organisms unable to tolerate such
conditions may suffer hypoxia-induced mortality and / or stress including
diminished feeding and growth rates (Diaz & Rosenberg 1995). In particular, corals are more sensitive to
low oxygen levels than other benthic groups.
For this EIA study, the WQO standard that bottom water DO should remain
above 2 mg L-1 90% of the time was broadly adopted.
Disturbance Impacts To Marine Mammal Habitat
8.6.13 Marine construction and dredging may result in the generation of
underwater noise and an increase in marine traffic. Although records of finless porpoise sightings and strandings
appear to show these cetaceans do not frequently utilise the Assessment Area,
nevertheless, cetaceans are protected under the Wild Animals Protection
Ordinance (Cap. 170), 1980 and so any lethal and sublethal impacts due to, for
example, underwater noise associated with the project will be deemed
unacceptable.
8.6.14 Studies have shown that because of the efficient transfer of sound
in water, cetaceans can detect noises associated with vessels similar to
dredgers at distances up to approximately 5 km. Finless Porpoises use
ultrasonic pulses for echolocation of prey, navigation and communication with
conspecifics (Jefferson, 2000) so that noise disturbance may lead to
behavioural changes. There is evidence
suggesting that some cetacean species will minimise their use of areas affected
by underwater noise. However, noise generated by underwater construction
activities such as dredging and pile-driving have their highest energy at lower
frequencies, from about 20 Hz to 1 kHz, whereas the important communication
channels for smaller whales, dolphins and porpoises tend to range from 1kHz to
10kHz (Wűrsig
et al. 2000). It is therefore unlikely that construction activities
associated with this Project would cause substantial impact to finless porpoises
utilizing nearby waters.
8.6.15 In addition, finless porpoises in Hong Kong have been found killed
and injured by vessel collisions (Parsons & Jefferson, 2000). Overall, about a fifth (17%) of known
finless porpoise mortalities in Hong Kong have been attributed to vessel
collision (Jefferson, 2000). Vessel collision (also termed boat strike) is
therefore one of the most significant anthrogenically-induced causes of finless
porpoise mortality locally.
Operation
Phase
Direct Impacts
8.6.16 No direct marine ecological impacts are expected during the
operation stage of the Project.
Indirect Impacts
8.6.17 Potential indirect impacts on marine ecology arising during the
operation phase may include water quality impacts on coral sites due to the
effects of altered coastal configuration and infrastructure on the hydrodynamic
flow pattern of Junk Bay.
8.6.18 Other water quality issues assessed in Section 5 were impacts of
emergency discharge of sewage in the event of malfunction of HATS (sections
5.7.22-5.7.31 refer). Potential impacts resulting from such a malfunction were
discussed largely in the context of the danger posed to users of water
recreational facilities proposed for Inner Junk Bay. As the functioning (or
malfunctioning) of sewage discharge of HATS does not fall under the remit of
this Project, assessment of marine ecology impacts resulting from emergency
sewage discharge are not discussed in further here.
8.6.19 Because the proposed development plans of the Project do not include
port facilities such as docks or piers (except for a recreational water sports
facility which will consist mostly of non-motorised vessels such as windsurfers
and rowing boats), increased marine traffic during the operation phase was not
considered to be of concern in relation to potential impacts on Finless
Porpoises. Operational phase impacts on Finless Porpoises are therefore not
considered further in this assessment.
8.7.1
Potential ecological impacts to
habitats in the assessment area resulting from the current Project have been
evaluated according to Table 1 of Annex 8 of the TM-EIA.
Construction
Phase
Rocky shore habitat
8.7.2
The proposed WCR reclamation would
cover all areas between the proposed seawall and margin of the land. As a
result, all natural rocky shore habitat enveloped by the seawall in the
northeast corner of Junk Bay would be permanently lost. This loss of habitat
would be an unavoidable consequence of the project. Taking into account the
irregular configuration of the coastline, a total of approximately 1km of rocky
shore would be lost.
8.7.3
The loss of natural rocky shore would
be partially compensated by the construction of 1.05km of sloping rubble mound
seawall. Rubble mound seawall consists of irregular medium to large sized
boulders, which would provide suitable substrata for recolonisation by
intertidal flora and fauna. In addition, the 30 piers constructed in the sea
for the CBL would also provide hard substrata for colonisation.
8.7.4
Surveys along the Chiu Keng Wan coast
subject to the proposed reclamation found a single intertidal rock pool on the
upper shore, which was temporarily utilised as a spawning site by a species of
potential ecological interest, the Grassy Puffer. As discussed in Section
8.4.23, this species, which lives in open water, may temporarily strand itself
in high shore rock pools between spring tides in order to spawn. Owing to the
reported moderate abundance of this species in Hong Kong waters and the
prevalence of natural rocky shore habitat, which comprises about 62% of the
Hong Kong coastline, loss of this one rock pool spawning site was considered to
be a very minor impact . Nevertheless, construction activities such as filling
may kill any individuals that have stranded in the rock pool during the
construction phase and therefore mitigation measures to rescue individuals are
recommended.
Table 8.9 Overall Impact Evaluation for Rocky
Shore Habitat
Evaluation Criteria
|
Rocky shore habitat
|
Habitat quality
|
Habitat quality was considered low-medium
|
Species
|
Potential loss of intertidal spawning site for one species of
potential conservation interest, the Grassy Puffer, Takifugu niphobles
|
Size/Abundance
|
1km length of natural rocky shore
|
Duration
|
Loss of habitat would be permanent
|
Reversibility
|
Loss of natural rocky shore is irreversible but would be partially
compensated by availability of sloping rubble mound seawall for
recolonisation by rocky shore organisms
|
Magnitude
|
The scale of habitat loss is low in the context of similar surrounding
similar habitat
|
Overall impact conclusion
|
Low
|
Sandy shore habitat
8.7.5
WCR reclamation would result in the
loss of 3 sandy coves along the Chiu
Keng Wan coast with a combined length of approximately 0.2km. The loss of this habitat
and its associated fauna from the west coast of Junk Bay would be permanent.
Overall, impacts to sandy shore habitats were considered low-moderate in scale
only. As described in section 8.5.5, sandy shore habitats were considered
low-moderate ecological value. Although the habitats were observed to be
relatively free from physical modification and disturbance from recreational
use, they were also noted to be small in size and supported faunal assemblages
with extremely low diversity.
Table 8.10 Overall Impact Evaluation for Sandy Shore Habitat
Evaluation Criteria
|
Sandy shore habitat
|
Habitat quality
|
Low-moderate
|
Species
|
No species of recognised conservation interest were recorded
|
Size/Abundance
|
Small. Stretches of sandy shore inside the reclamation footprint have
a combined length of approximately 0.2km
|
Duration
|
Loss of habitat would be permanent
|
Reversibility
|
Loss of natural sandy shore would be irreversible
|
Magnitude
|
The scale of habitat loss is moderate in the context that this
habitat is generally uncommon in the Assessment Area
|
Overall impact conclusion
|
Low-Moderate
|
Artificial Seawall habitat
8.7.6
Artificial seawall subject to loss was
vertical seawall of limited ecological value and would not be of particular
ecological concern. Impact of the WCR
reclamation on artificial seawall habitat was rated as very low.
Table 8.11 Overall Impact Evaluation for Artificial Seawall Habitat
Evaluation Criteria
|
Artificial seawall
habitat
|
Habitat quality
|
Low
|
Species
|
No species of note were identified.
|
Size/Abundance
|
Approximately 0.25km of vertical seawall would be lost.
|
Duration
|
The loss of vertical seawall would be permanent
|
Reversibility
|
Loss of vertical seawall would be partially compensated by
construction of sloping rubble mound seawall, which would better mimic
natural hard shore habitat.
|
Magnitude
|
Low
|
Overall impact conclusion
|
Very Low
|
Hard Substrata Subtidal Habitat
8.7.7
WCR reclamation would lead to the
permanent loss of areas of subtidal hard substrata that supports a sparse and
patchy cover (<1%) of hard corals as well as a sparse or occasionally
moderate cover (0 – 15% cover) of soft and gorgonian corals. This coral loss
would be an unavoidable consequence of the project. Owing to their sparse
cover, generally small size and low species richness and because they are
common species which are well represented in coral communities across Hong
Kong, the loss of the hard corals was considered to be of limited ecological
significance. Similarly, although soft corals and gorgonians attained moderate
cover namely inside the southern margin of the reclamation area, it was known
that the species identified are widespread and commonly found along the coastal
fringes of Hong Kong. Moreover, the
current WCR engineering design was proposed to avoid a 2.5ha area of very high
abundance of soft and gorgonian corals located close to Lei Yue Mun at the
southwest corner of Junk Bay.
8.7.8
Indirect impacts on corals due to WCR
reclamation and CBL bridge construction are assessed with reference to findings
presented in Section 5 of this report. The proposed WCR reclamation would be
constructed in 3 phases (refer to Figure 5.8) and would
involve a construction sequence and methods that are designed to lessen
resulting water quality impacts due to dispersion of suspended sediments. Works
for the WCR reclamation would only require dredging at Phase I area, located at
the southern end of the Chiu Keng Wan coast. There would be no dredging to
remove seabed sediment at reclamation Phases II and III since bottom sediments
would be left in situ at these locations. Water quality impact arising due to filling would also be avoided
since this land formation work would be contained behind an enclosing
seawall. To construct the seawall
sections for Phases II and III, a Deep Cement Mixing (DCM) process would be
used. This is a construction method that results in less water quality impact
than conventional seawall construction methods that require dredging. Similarly, no dredging would be conducted
for the placement of CBL bridge piers. Instead, piers would be installed using
a Large Diameter Bored Piling (LDBP) platform, which is considered to be a
construction method that would cause negligible release of sediment into the
water column.
8.7.9
In this way, the major source of water
quality impact arising from the Project, which may impact coral sites in Junk
Bay, would be associated with Phase I WCR reclamation works. [Note: Phases I,
II and III of the WCR reclamation would not be constructed
concurrently.] Using a sediment plume prediction model, a worst-case scenario
of Phase I works, called Scenario A was examined to determine potential impacts
on coral sites. The modelling results
of Scenario A show the predicted unmitigated water quality impacts of dredging
a total of 20,000m3 of sediment using a closed-grab, assuming 12
working hour each day and lasting for 27 days. Further details on the
(conservative) assumptions of Scenario A are described in Sections 5.5.24 –
5.5.25 and 5.5.29 – 5.5.30. Apart from the proposed dredging works, Scenario A
modelling also incorporates water quality impacts arising from concurrent
seawall construction (refer to Table 5.16).
8.7.10 According to the Scenario A sediment plume modelling results,
construction works would not cause levels of SS at coral sites in Junk Bay to
breach WQO standards. At the southwest Junk Bay coral site (S1)(refer to Figure
8.1), corals would experience mean depth-averaged SS levels of 4.49mg L-1
and 6.36mg L-1 in the dry and wet seasons respectively. This corresponds to a
14.3% and 21.4% elevation of SS levels above baseline respectively, which would
be in compliance with the WQO for Junk Bay. At the Junk Island coral site (S2), depth-averaged SS levels would
be 3.94mg L-1 and 5.07mg L-1 in the dry and wet seasons
respectively. This would represent a 2.1% and 1.8% elevation in depth-averaged
SS levels above baseline respectively, which indicates that WQO would be
achieved at this coral site during construction works. This assessment
indicates no unacceptable adverse impact on coral sites due to elevated SS
levels during the construction phase would be anticipated. Figure DA 1 and Figure WA 1 of Appendix 5.3 shows the mean depth-averaged SS levels for Scenario A for the dry
and wet season respectively. .
8.7.11 Maximum sedimentation rates at Junk Bay coral sites (refer to Figure
8.1) under Scenario A conditions were predicted to remain well below critical
levels. At the Southwest Junk Bay coral site (S1), maximum sedimentation rate
were predicted to be 3.3g m2 day-1 and 3.2g m2
day-1 in the dry and wet season respectively. Similarly, maximum
sedimentation rates at the Junk Island coral site (S2) were predicted to be 3.3
g m2 day-1 and
3.2 g m2 day-1 in the dry and wet season respectively. No
unacceptable adverse impacts to corals sites due to increased sediment
deposition during the construction phase was anticipated. Figure DA 2 and Figure WA 2 of Appendix 5.3 shows the maximum sedimentation rate for Scenario A for the dry and
wet season respectively.
8.7.12 In terms of sediment impacts on coral communities, water quality
mitigation measures were recommended in Section 5 including the deployment of
silt curtain to limit the dispersal of the sediment plume. With employment of water quality mitigation
measures, it was considered that no unacceptable indirect sediment plume
related impacts on coral areas would occur.
8.7.13 Figure DA 3 and Figure WA 3 of Appendix 5.3 illustrate mean depth-averaged dissolved oxygen conditions during
Scenario A for the dry and wet season respectively. The average dissolved oxygen
of the bottom waters under Scenario A is shown in Figure DA 4 of Appendix 5.3 and WA4 of Appendix 5.3. These modelling results
indicated that under Scenario A, there would be a negligible impact on
dissolved oxygen levels.. Dissolved oxygen levels at the Southwest Junk Bay
(S1) and Junk Island (S2) coral sites would be in compliance with the WQOs of
Junk Bay. During the construction
phase, no unacceptable adverse impacts at these coral sites beyond predicted baseline
water quality conditions were anticipated.
8.7.14 The operation phase impacts on water quality due to changes in
coastal configuration arising from the Project were assessed in Section 5. According to this assessment, it was
concluded that changes in hydrodynamics due to the WCR reclamation and CBL
would have little effect on water quality. All water quality parameters would
be in compliance with WQOs at coral sites in Junk Bay and no unacceptable
adverse impacts were predicted.
Table 8.12 Overall Impact Evaluation for Hard Substrata Subtidal Habitat
Evaluation Criteria
|
Hard substrata subtidal
habitat
|
Habitat quality
|
Chiu Keng Wan (i.e. reclamation area) - Low
West coast of Junk Bay (excluding and at the south of Chiu Keng Wan)
- Medium
|
Species
|
Hard, soft and gorgonian corals occur at Chiu Keng Wan as well as to
the south along the west coast of Junk Bay
|
Size/Abundance
|
Chiu Keng Wan supports sparse hard corals and sparse to moderate
cover of soft and gorgonian corals
|
Duration
|
Direct loss of corals inside the reclamation would occur during the
construction phase and would be permanent.
Indirect water quality impact on coast supporting corals adjacent to
the reclamation would occur for approximately 1 month during dredging at
Phase 1 of WCR reclamation. Due to
construction methods, water quality impact are not expected during filling
and pier construction
|
Reversibility
|
Loss of corals would be irreversible though 1km sloping seawall may
provide hard substrata for recolonisation
|
Magnitude
|
Direct impact: Low-moderate
Indirect impact: Very Low
|
Overall impact conclusion
|
Low with mitigation
|
Soft Substrata Subtidal Habitat
8.7.15 WCR reclamation would cause direct loss of approximately 16.3ha of
seabed, whilst pier construction for CBL would lead to the loss of
approximately 0.2ha. Loss of this disturbed habitat, which supports low
abundance of infauna of no recognised conservation interest, was considered to
minor in the context of similar surrounding habitat.
Table 8.13 Overall Impact Evaluation for Soft Substrata Subtidal Habitat
Evaluation Criteria
|
Soft Substrata Subtidal
Habitat
|
Habitat quality
|
Low
|
Species
|
No species of conservation interest were identified
|
Size/Abundance
|
16.5ha of seabed would be lost due to WCR reclamation
|
Duration
|
Loss of this habitat would be permanent
|
Reversibility
|
Habitat loss would be irreversible
|
Magnitude
|
The scale of habitat loss is low in the context of similar
surrounding similar habitat
|
Overall impact conclusion
|
Low
|
8.7.16 Based on finless porpoise sightings records used to establish
baseline ecological conditions, there is no evidence that finless porpoises
utilise Junk Bay. The loss of sea area due to the project would not constitute
direct loss of marine mammal habitat for the Finless Porpoise.
8.7.17 Indirect disturbance impacts arising from the project are expected
to be very low given that finless porpoises are not expected to present in the
vicinity of the works and that construction methods would not involve
production of high power underwater sound. Construction activities for WCR
reclamation would include dredging, placement of boulders to construct the
rubble mound seawall and filling behind the seawall. Dredging, seawall
construction and filling for the three phases of the WCR reclamation is
expected to last 1, 8 and 12 months respectively. Marine construction
activities for the CBL would be bored piling works. These activities are
expected to generate low intensity underwater sounds that would not be
disruptive to porpoises.
8.7.18 The increase in marine traffic associated with the WCR reclamation
would include a maximum of 16 slow moving barges entering and leaving Junk Bay
each day. The increase in disturbance from marine traffic is considered minor
in the context of the existing high levels
(400 vessel movements in daylight hours) of marine traffic in the busy
Tathong Channel.
8.7.19 In summary, owing to the lack of sightings of Black Finless
Porpoises from Junk Bay and adjacent areas based on monitoring records, a
relatively low increase in large, slow moving vessels and general construction
phase activities would not be expected to adversely affect the porpoises, which
appear not to frequent these waters.
Table 8.14 Overall Impact Evaluation for Marine Mammal Habitat
Evaluation Criteria
|
Marine Mammal Habitat
|
Habitat quality
|
Low
|
Species
|
Black Finless Porpoise, Neophocaena phocanoides
|
Size/Abundance
|
No Finless Porpoise have been sighted within or in the immediate
vicinity of Junk Bay.
|
Duration
|
Disturbance from vessel movements and noise may occur in the
construction phase
|
Reversibility
|
Impacts would occur during the construction period
|
Magnitude
|
Low
|
Overall impact conclusion
|
Very Low
|
8.8.1
Following
EIAO-TM Annex 16 guidelines, mitigation
measures are discussed in this section to avoid, minimise and compensate for
identified ecological impacts.
Avoid
8.8.2
The
proposed alignment of the WCR has been substantially revised, with consequent
large reductions in potential impacts to terrestrial and marine ecological
sensitive receivers. Under the previously proposed alignment (as presented in
the Western Coast Road EIA Report), the WCR within Junk Bay would have been
constructed largely on reclaimed land from Tseung Kwan O to Lei Yue Mun
Headland, impacting 2.5ha area of very high abundance
of soft and gorgonian corals located close to Lei Yue Mun at the southwest
corner of Junk Bay. The revised WCR alignment presented in this EIA Report
would avoid impacts to this area of corals.
Minimise
8.8.3
Recent surveys of hard substrata
subtidal habitats directly affected by WCR reclamation reveal very low coverage
by corals (typically, hard coral coverage was less than 1%, and octo-coral from
0 – 15%), with only common species recorded, and these habitats were considered
of low ecological value. Nevertheless, it is recommended however that the
feasibility of transplanting potentially impacted hard corals from the
reclamation area to suitable nearby habitats is investigated during the
detailed design stage of the Project. To achieve this aim, surveys of the
proposed reclamation area should be conducted during the detailed design stage,
at least 8 months prior to the start of the construction phase. These surveys
should focus on identifying and mapping hard corals that would be suitable for
transplantation (i.e., corals encrusting small boulders of a manageable size
that can be moved by divers with lifting aids). If corals suitable for
transplantation are identified during these surveys, a detailed transplantation
methodology (including monitoring of transplanted corals) should be drafted
during the detailed design stage of the Project.
8.8.4
During construction phase for Phase I
reclamation, mitigation measures used to control water quality (e.g. deployment
of a silt curtain and reduced dredging rate as presented in Section 5) would
serve to protect corals in proximity to the reclamation to acceptable levels.
Construction methods for reclamation would involve filling within enclosed
areas behind seawalls with no dredging required for Phase II and Phase III of
the WCR reclamation. These construction methods are expected to result in no
substantial water quality or marine ecological impacts. Nevertheless, silt
curtains would be deployed and other measures implemented to minimise any
potential water quality impacts during these works (sections 5.8.20-5.8.23
refer).
8.8.5
Mitigation is recommended to prevent
potentially lethal direct impacts of construction activities on individual
Grassy Puffers, if found stranded in rock pools within the works area. It is
recommended that the rock pool is visited after each spring tide (i.e. about
every 2 weeks) during the construction phase of the WCR reclamation until the
shore is no longer available due to filling associated with the Project. Any
puffers present in the pool should be captured and transferred to a temporary
holding tank. Captured fish should be returned to the sea outside the project
works boundary. Owing to their defence mechanism of self-inflating, particular
care should be employed when capturing and releasing the puffer fish (i.e.
keeping the fish submerged in water at all times to prevent gulping of air,
which could be lethal). Details of mitigation plans to rescue stranded puffers
should be drafted at the detailed design stage.
Compensate
8.8.6
The design of the Project has
undergone a detailed evaluation of different alignments and form of structures
for the WCR and the CBL, as well as alternative land use proposals for TCS and
PSK to arrive at the optimum planning, engineering and environmental solutions
which fit together in a coherent manner (as detailed in Section 2.3). With the preferred option, direct impacts to
marine habitats due to the Project have been minimised to the largest possible
extent within the constraints imposed by engineering and other environmental
considerations. Further reduction in impacts to intertidal habitats could be
achieved were the proposed portal and associated reclamation of WCR to be
shifted further north (see Figure 2.10). However, it was concluded that such a
scheme was not preferred to the selected option because:
·
The alternative option would require more
reclamation extending further (approximately 100m) into Junk Bay
·
The alternative option would cause substantial
adverse visual impact to existing and planned residential areas.
·
The alternative option would cause more
reduction in flushing capacity within inner Junk Bay and would likely cause
more adverse water quality impact.
·
The alternative option would cause greater air
quality and noise impacts on the existing and planned sensitive uses in TCS.
Given these constraints, further mitigation of impacts to intertidal
habitats through avoidance and minimisation was not considered feasible (a full
discussion and comparison of WCR alignment options is provided in Section
2.3.15 to 2.3.31 of the report). In
addition, as stated in Section 2.2.10, WCR is necessary to relieve the traffic
congestion envisaged at the existing TKO Tunnel and Wan Po Road due to the
continual development of TKO.
Compensation has therefore been adopted to mitigate for unavoidable
impacts where possible.
8.8.7
As described in Section 8.7.3 natural
rocky shore and hard subtidal substrata loss would largely be compensated for
through the construction of a 1.05km long sloping rubble mound seawall (the 30
piers of the proposed Cross-bay Link would also provide compensatory hard
substrata for colonisation). Elsewhere in Hong Kong, seawall habitat has been
found to be suitable to support coral growth. For instance, the rubble mound
seawall of the Lamma Power Station ash lagoon was found to support an abundance
of gorgonian corals as well as soft corals (Oceanway 2000), while artificial
substrate concrete dollos sea defence wall at the Sai Kung High Island dam are
known to support abundant hard corals (e.g. Wilson 2002). Moreover, the
coral site located at the Southwest Junk Bay was established by colonisation of
rubble dumped in a disused spoil ground. The rubble mound seawall consisting of
haphazardly arranged boulders is expected to provide a large amount of hard
substrata and large surface area for settlement and recruitment of coral
assemblages similar to those previously recorded from this coast.
8.9.1
With the effective implementation of
mitigation measures proposed in Section 8.8, residual impacts to marine ecology
are expected to be relatively minor. The loss of rocky shore and hard sub-tidal
substrata would be largely compensated for through the provision of the rubble
mound sloping seawall, which would provide suitable conditions for
recolonisation by intertidal and subtidal communities. The
transplantation/translocation of corals and Grassy Puffers would minimise
impacts to species of conservation interest potentially affected by the
proposed works. As Junk Bay is not a key habitat for marine mammals, no
substantial residual impacts to Finless Porpoise are expected. The most
substantial residual impact would therefore be the loss of sandy shore and soft
subtidal habitats, which would be unavoidable. However, neither of these
habitats were considered of particular ecological value, and the affected areas
are relatively small. Residual impacts resulting from the proposed works are
therefore considered relatively minor and acceptable.
8.10.1 The marine construction activities include constraints which act as
appropriate mitigation measures to control environmental impacts to within
acceptable levels (see Section 5).
Actual impacts of construction activities would be monitored through
impacts to water quality (see Section 5).
EM&A activities designed to detect and mitigate any unacceptable
impacts to water quality will serve to proactively protect against unacceptable
impacts to marine ecological resources.
The water quality monitoring programme will provide management actions
and supplemental mitigation measures to be employed should impacts arise,
thereby ensuring the environmental acceptability of the project. Site audits
will be carried out to ensure strict implementation of the recommended
mitigation measures. In this way, mitigation measures to safeguard water
quality during the construction phase would also serve the purpose of
protecting marine ecological resources.
8.10.2 It is recommended that the feasibility of transplanting potentially
impacted hard corals from the reclamation area to suitable nearby habitats be
investigated during the detailed design stage of the Project. If corals
suitable for transplantation are identified during these surveys, a detailed
transplantation methodology (including monitoring of transplanted corals)
should be drafted during the detailed design stage of the Project.
8.10.3 No unacceptable adverse impact on the medium value coral sites
within Junk Bay are anticipated. Nevertheless, EM&A for these coral sites
during dredging works for Phase I of the WCR reclamation is recommended.
Details of EM&A requirements are provided in the EM&A Manual which
includes parameters for monitoring the health and condition of corals during
dredging works of the Project and management actions and supplemental
mitigation measures should impacts arise. Overall, EM&A would serve the
purpose of protecting coral sites in Junk Bay and ensuring the environmental
acceptability of the Project.
8.10.4 In order to mitigate for the direct loss of existing hard substrata
subtidal habitat that supports mainly octo- and soft corals, the seawall was
recommended to be of rubble mound design. This seawall design was considered to
provide suitable substrata for coral colonisation. As the effectiveness of this mitigation measure may require a
long period to establish, EM&A to track recolonisation processes once the
seawall is completed is recommended. The details are provided in the
accompanying EM&A Manual.
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