This
section of the report presents the findings of the marine ecological impact
assessment associated with the construction and operation of an LNG terminal on
the
Legislative requirements and evaluation
criteria relevant to the study for the protection of species and habitats of
marine ecological importance are summarised below. The details on each are
presented in Annex 9.
1.
Marine Parks Ordinance (Cap 476);
2.
Wild Animals Protection Ordinance (Cap
170);
3.
Protection of Endangered Species of
Animals and Plants Ordinance (Cap 586);
4.
Town Planning Ordinance (Cap 131);
5.
Hong Kong Planning Standards and
Guidelines Chapter 10 (HKPSG);
6.
The Technical Memorandum on Environmental
Impact Assessment Process under the Environmental Impact Assessment Ordinance
(EIAOTM);
7.
United Nations Convention on Biodiversity
(1992);
8.
Convention on Wetlands of International
Importance Especially as Waterfowl Habitat (the Ramsar
Convention); and,
9.
PRC Regulations and Guidelines.
10. City
University of Hong Kong (2001). Agreement No. CE 62/98, Consultancy Study on
Fisheries and Marine Ecological Criteria for Impact Assessment, AFCD, Final
Report July 2001.
The
marine ecological habitats in the immediate vicinity of the South Soko Island have undergone some anthropogenic disturbance
through reclamations in Sai Wan and Tung Wan as a
result of the site formation for the Detention Centre (now
decommissioned). Even before this
facility was built, the village developments at Ha Tsuen
and Sheung Tsuen (both now
abandoned) had resulted in some reclamation over the previous coastline, in the
form of piers and seawalls. To the
east of the South Soko Island lies the active mud
disposal ground at South Cheung Chau (approximately 6
km from the terminal) and to the west a former marine sand borrow area
(approximately 1.3 km from the terminal) which remains as a gazetted sand
dredging and mud disposal area. The
Hong Kong Government has recently constructed a jetty and low level radioactive
waste store within a bay on North Soko Island (Siu A Chau).
The waters and coastal areas of Southwest Lantau including the Soko Island
group, which are located away from the major population centres of Hong Kong,
have been considered by some academics, government and green groups to be a
general area of high ecological value including from a marine perspective. Recently gathered information on the
West Lantau area would also indicate high ecological
value.
The
findings of the literature review and field surveys and, an evaluation of the
ecological importance of marine resources within the Study Area are summarised
in the following section. The
details are presented in full in Annex 9. The ecological resources and importance
of marine habitats, in particular the South Soko
Islandˇ¦s various habitats and organisms, have been characterised with reference
to the available literature, comprehensive seasonal field surveys, comparisons
with other similar habitats in Hong Kong and the criteria presented in Annexes 8 and 16 of the Technical
Memorandum on Environmental Impact Assessment Process under the Environmental
Impact Assessment Ordinance (EIAO-TM).
Due
to the limited literature available for some components of the marine
environment, field surveys were necessary to fill the information gaps
identified for the baseline conditions of the habitats. Detailed and comprehensive seasonal
surveys were conducted examining the major habitats and species surrounding the
South Soko Island and the pipeline, cable and watermain alignments.
The baseline surveys have included both the dry and wet seasons. The findings of the field surveys are
presented in Annex 9.
The
key finding of the literature review was the recorded presence in the waters in
southern Lantau of both of Hong Kongˇ¦s resident
marine mammal species, the Indo-Pacific Humpback Dolphin Sousa chinensis and the Finless Porpoise Neophocaena phocaenoides.
For
this EIA, an extensive programme of vessel-based surveys has been conducted to
supplement data available from ongoing long-term AFCD monitoring. In accordance with the requirements of
the Study Brief, the surveys have been conducted on a monthly basis covering
the period October through May.
Since this EIA study commenced in July, surveys were also conducted
during July, August and September.
These surveys have provided a detailed overview of dolphin utilisation
of Hong Kong western waters spanning Southwest Lantau,
West Lantau, Northwest Lantau
and Deep Bay areas. During the
field surveys, dolphins were observed throughout the surveyed areas except
directly south of the Sha Chau
and Lung Kwu Chau Marine
Park and at the very northern end of the Deep Bay survey area.
The
survey data gathered (July 2005 to May 2006) has indicated that Deep Bay has
relatively low densities (0.08 - 0.23 dolphins
km-2) and a low abundance (<10 dolphins). West Lantau
had higher dolphin densities (1.71 - 2.81 dolphins
km-2) and a higher abundance (47 ˇV 78 depending on the season)
of dolphins. It was evident that
dolphins use this area as a part of their habitat in all seasons. Southwest Lantau
had lower levels of dolphin density (0.10 - 0.44 dolphins
km-2) and abundance (6 - 29 dolphins depending on the season)
than West Lantau but was higher than Deep Bay. Northwest Lantau had lower levels of dolphin density
(0.57-0.94) compared to West Lantau but similar
abundance (49-82). Northwest Lantau had higher levels of dolphin density and abundance
than Deep Bay and Southwest Lantau.
Finless Porpoises were only seen in
Southwest Lantau and estimates of abundance (0 - 15
porpoises depending on the season) and density (<0.01 - 0.17 porpoises km-2)
were low. Other areas of Hong Kong
such as key habitats at Lamma and Po Toi support considerably higher densities (Lamma: 0.02 - 0.52 porpoises km-2, Po Toi; 0.02 - 0.17 porpoises km-2) and abundance (Lamma: 4 - 90 porpoises, Po Toi:
4 - 32 porpoises) of these animals ([1]).
Within
all of the marine areas of Hong Kong, the marine waters Southwest of Lantau Island (including the Soko
Islands area) are the region where the Indo-Pacific Humpback Dolphin and
Finless Porpoise significantly overlap in distribution. It appears that most other areas are
utilized by one or the other species.
Thus, those areas that are strongly influenced by the Pearl River
outflow (Deep Bay, West Lantau, Northwest Lantau, and Northeast Lantau)
appear to offer suitable conditions for the Indo-Pacific Humpback Dolphins,
which feed mostly on estuarine fish (Jefferson 2000) ([2]). Those areas that are more
marine-influenced (Southeast Lantau, Lamma, Po Toi, and the eastern
waters) are used nearly exclusively by Finless Porpoises (Jefferson et al.
2002) ([3]).
For
this EIA a comprehensive series of dive surveys were conducted on South Soko and its environs.
The dive surveys at South Soko yielded similar
results to those reported previously by BCL ([4])
in that hard corals were in low abundance and diversity. In total, fifteen hard coral species and
four octocoral species, were
recorded within the Study Area (Annex 9).
The majority were common faviids, poritids and siderasteriids, with
three predominant species ˇV Oulastrea crispata, Psammocora sp. and
the ahermatypic cup coral Balanophyllia sp. Corals occurred in
extremely low abundance and percentage cover estimates ranged from 1 - 5%. Of the live corals recorded, many were
highly damaged and bioeroded by macroborers
and barnacles. Consequently, the
majority of colonies exhibited partial mortality. The corals recorded are all common Hong
Kong species with the exception of the relatively little known hard coral, the
False Pillow Coral Pseudosiderastrea tayami which
was recorded on the southern coast of
the South Soko Island.
Literature
was reviewed as part of the EIA which indicated that field sampling would be
necessary due to the lack of comprehensive data in the Project Area. Consequently, for this EIA a
comprehensive series of benthic surveys were conducted around South Soko and along the gas pipeline route. A total of 96 grab samples were taken
from 16 sites during both the wet and dry seasons: 8 of the sites (48 grabs)
were located close to South Soko Island; 6 of the
sites (36 grabs) were located along the submarine pipeline alignment; and 2 of
the sites (12 grabs) were located off Black Point. In both seasons, benthic assemblages
were dominated by polychaete worms, except off Black
Point were bivalves were recorded in higher numbers. In terms of diversity and abundance,
benthic communities at the sites were similar to other locations reported in
Hong Kong. At sites close to the
South Soko Island, the level of diversity and biomass
was generally higher than the Hong Kong average reported from the
literature. In addition, a low
number of amphioxus Branchiostoma belcheri ([5])
were recorded in Tung Wan on the east coast of South Soko
Island. This area was previously
disturbed during reclamation associated with construction of a Detention Centre
in the late 1980ˇ¦s. The presence of
this species therefore indicates that it survived the disturbance or was able
to recolonise the bay in the intervening years.
Two species of Horseshoe Crab (Tachypleus
tridentatus and Carcinoscorpius
rotundicauda) have been recorded in Hong Kong
waters. In Hong Kong, the intertidal sand/sandy-mud flats at Shui
Hau and San Tau, on Lantau Island, the mud flats at Pak Nai,
in Deep Bay have recorded juveniles of both species, whereas, adult horseshoe
crabs are occasionally fished from the subtidal mud
along the northwest coast to the Lantau Island,
including Tai O, Yi O, Sham Wat Wan, Sha Lo Wan and Tung Chung Bay. All of the horseshoe crab breeding
grounds are located far away from the LNG terminal (at least 13 km), proposed
gas pipeline (at least 2 km), submarine cable and watermain
(at least 11 km).
Quantitative
transect surveys and spot checks were conducted on natural rocky shore and
artificial seawalls on the west, east and south coasts of South Soko Island.
Rocky shore species were common and widespread and no species of note
were recorded. At South Soko, assemblages with the highest diversity were recorded
on the south coast of the island.
In comparison to records of other shores in Hong Kong reported in the
literature, the diversity of intertidal biota at
The
sandy shores at South Soko and Shek
Pik supported very low species diversity in the dry
and wet season, which is a typical feature of mobile sandy shores with unstable
substrates.
The
details of all of the baseline surveys conducted for this EIA are summarised in
Table 9.1.
Table 9.1 Marine
Ecology Baseline Surveys
|
Survey Type |
Methodology |
Date |
|
Intertidal
Assemblages at South Soko |
Rocky shore/ artificial shoreline Quantitative (belt transects at 7
locations) survey, three 100 m belt transects (at high, mid and low intertidal zones) for each location, covered both wet and
dry seasons. Sandy Shore Quantitative (line transects at two locations)
survey, 50 x 50 x 50cm core at three points (high,
mid and low intertidal zones) along
each of the transects, covered both wet and
dry seasons. |
8 & 9 March, 28 & 29 July, 14
September 2004, 29 & 30 September 2005 and 27 January 2006 |
|
Intertidal
Assemblages at Shek Pik |
Rocky shore/ artificial shoreline Quantitative (belt transects at 1
locations) survey, three 100 m belt transects (at high, mid and low intertidal zones) covered both wet and dry seasons. Sandy Shore Quantitative (line transects at 3 locations)
survey, 50 x 50 x 50cm core at three points (high,
mid and low intertidal zones) along
each of the transects, covered both wet and
dry seasons. |
30 August 2005 & 14 March 2006 |
|
Subtidal
Benthic Assemblages |
Quantitative grab sampling survey;
covered both wet and dry seasons.
Six stations sampled in each of 10 locations, covering the reclamation
area, approach channel and turning circle, and along the pipeline corridor. |
25 & 26 February, 5 & 6 July, 9
September, 8 November 2004, 23 September 2005 and 13 December 2005. |
|
Subtidal
Hard Bottom Habitat (Coral) |
Quantitative (Rapid Ecological
Assessment (REA) technique, a total of twenty three 100 m transects at 15
locations) and qualitative (recorded within Study Area and areas in the
vicinity, 3 locations); covered wet season. |
9 & 15 May 2004, 29,30 September
& 3 October 2005. |
|
Marine Mammals |
Land-based visual survey during daytime,
5 days per month and 6 hours per day, covered four seasons and 12 months. |
13, 14, 21, 23 & 26 February, 8, 9,
10, 17 & 18 March, 16, 19, 20, 21 & 26 April, 10, 12, 14, 19 & 25
May, 10, 14, 17, 18 & 28 June 2004, 23, 26, 27, 28 & 29 July 2004,
25, 26, 27, 30 & 31 August, 6, 7, 13, 14 & 22 September 2004, 27, 28,
29, 30 & 31 October 2004, 16, 17, 24, 25 & 26 November 2004, 16, 21,
28, 30 & 31 December 2004, 10, 12, 14, 17 & 28 January 2005 |
|
|
Quantitative vessel based survey using
line transect methods spanning Hong Kong western waters (Deep Bay, Southwest Lantau, Northwest Lantau and
West Lantau) 6 days per month |
18, 19, 20, 21, 22, 25, 26, 27 July
2005, 3, 4, 5,15,24 & 25 August 2005, 5,7,15, 16 & 20 September 2005,
5, 6, 7, 17, 18 & 19 October 2005, 22, 24, 25, 28, 29 & 30 November
2005, 6,7,8 & 22 December 2005, 13, 16, 17, 19, 20 & 24 January 2006,
1, 2, 3, 7, 8 & 9 February 2006, 17, 23, 28, 29, 31 March 2006, 3, 6, 18,
25, 26, 27 April 2006, 2, 4, 8, 9, 10, 11 May 2006. |
The waters and coastal areas of Southwest Lantau including the Soko Island
group, which are located away from the major population centres of Hong Kong,
have been considered by some academics, government and green groups to be a
general area of high ecological value including from a marine perspective. As discussed in Section 9.3.1 both dolphins and porpoises are sighted in the waters
of Southwest Lantau, although typically at different
times of the year.
There
have been a variety of studies, which have investigated the marine ecology of
Southwest Lantau waters and as a result of these, in
particular the AFCD-commissioned Marine Park feasibility study ([6]),
both the coastal waters off Southwest Lantau Island
and the waters around the Soko Island Group have been
proposed for designation as Marine Parks.
Recently gathered
information on the West Lantau area would also
indicate high ecological value. It
is important to note that there are significant spatial variations in the
ecological characteristics within this large area. To provide information of key relevance
to the marine ecological assessment, the ecological importance of habitats
presented in this baseline was therefore primarily focused on the vicinity of
the works areas of the proposed Project.
The ecological importance of the habitats was determined with
reference to the following:
ˇP
Literature
review findings;
ˇP
Findings
of the field surveys;
ˇP
Comparison
with other outlying islands in Hong Kong, as well as South Lantau;
and,
ˇP
Annexes 8 and 16 of the EIAO TM.
The
ecological importance of the marine habitats and their locations relative to
the LNG terminal layout are summarised in Table 9.2. The
key findings are presented below
ˇP
Areas to be Reclaimed: The information on marine ecological
resources presented in this report has not identified any habitats within the
reclamation areas that are of high ecological importance.
ˇP
Inshore Marine Waters of
ˇP
Marine waters of the Proposed Pipeline
Corridor:
The waters along or in proximity to the proposed submarine pipeline
corridor have higher numbers of sightings of Sousa chinensis and few, if any,
sightings of Neophocaena phocaenoides. Along the submarine pipeline corridor,
the waters around West Lantau have been classified as
Sousa chinensis
habitat and have the highest density of sightings recorded in Hong Kong.
The ecological importance of the marine
habitats and their locations relative to the LNG terminal layout are summarised
in Table
9.2.
Table 9.2 Ecological
Importance of the Marine Habitats in the Vicinity of the Works Areas
|
Habitat |
Ecological Importance |
|
Natural Rocky Shore |
Medium at |
|
Artificial Shoreline |
Low at |
|
Sandy Shore |
Low at South Soko,
except Medium for Pak Tso Wan. Low at Shek Pik. |
|
Subtidal
Hard Surface Habitat along Natural Rocky Shore |
Low except Low to Medium at sites with Pseudosiderastrea tayami on
south coast of |
|
Subtidal
Hard Surface Habitat along Artificial shoreline |
Low |
|
Subtidal
Soft Bottom Habitats at South Soko |
Low to Medium, except Medium for Tung
Wan where amphioxus was reported. |
|
Subtidal
Soft Bottom Habitats along the Corridor of the Proposed Submarine Natural Gas
Pipeline |
Low |
|
Marine Waters at Tung Wan and Sai Wan of |
Low for Sousa chinensis, Medium for Neophocaena phocaenoides. |
|
Marine Waters at the southeast of |
Low for both Sousa chinensis and Neophocaena phocaenoides. |
|
Marine Waters along the Corridor of the
Proposed water main and submarine cable circuit |
Medium for both Sousa chinensis, Low for Neophocaena phocaenoides. |
|
Marine Waters along the Corridor of the
Proposed Submarine Natural Gas Pipeline |
Medium for both Sousa chinensis and Neophocaena phocaenoides west of South Soko. Medium in southwest Lantau
for Sousa chinensis,
Low for Neophocaena phocaenoides. High in west and northwest Lantau only for
Sousa chinensis. Low at Black Point landing area only for Sousa chinensis. |
The
construction and operation phases of the proposed LNG terminal and the
installation of the submarine gas pipeline, water main and power cable have the
potential to affect marine ecological Sensitive Receivers (SRs). The marine ecological SRs have been identified in accordance with the EIAO-TM criteria and are consistent with
the ones identified in the Water Quality Assessment (Section 6):
ˇP
Marine
Parks;
ˇP
Seagrass
Beds, Mangroves, Intertidal Mudflats and Horseshoe
Crabs; and
ˇP
Chinese
White Dolphin Protection Zone in Mainland China.
The marine ecological SRs
and their distance from the LNG terminal site, connecting pipeline and
utilities (power cable and water mains) are listed in Table 9.3 and their location is shown in Figure
6.4
(see Section 6).
Table
9.3 Approximate Shortest
Distance to Marine Ecological Sensitive Receivers (SRs)
around Proposed LNG Terminal at South Soko and
Submarine Pipeline Section from
|
Sensitive Receiver |
Name |
ID |
Distance (km) from SR to |
|||
|
LNG terminal |
Water Mains |
Cable |
Pipeline |
|||
|
Seagrass
Beds |
Pak Nai |
SR2 |
>
10 |
>
10 |
>
10 |
5.1 |
|
|
Tung Chung Bay |
SR39 |
>10 |
7.8 |
7.8 |
6.6 |
|
Marine Parks |
Designated Sha
Chau and Lung Kwu Chau |
SR6a-d |
>
10 |
>
10 |
>
10 |
<
1 |
|
Potential Marine Parks |
Proposed Fan Lau Marine Park Proposed Soko
Island Marine Park |
MP19a-19c various |
>5 within |
3.9 within |
3 within |
<
1 within |
|
Intertidal
Mudflats |
Pak Nai |
SR1 |
>
10 |
>
10 |
>
10 |
1.7 |
|
|
Tai O |
SR12 |
>
10 |
5.7 |
5.7 |
1.9 |
|
|
Yi O |
SR14 |
>10 |
5.6 |
5.1 |
1.7 |
|
|
Shui
Hau Wan |
SR33 |
6.6 |
2.85 |
2.1 |
5.9 |
|
Mangroves |
Pak Nai |
SR2 |
>
10 |
>
10 |
>
10 |
5.1 |
|
|
Tung Chung Bay |
SR39 |
>10 |
7.8 |
7.8 |
6.6 |
|
|
Fan Lau Tung Wan |
SR15b |
7.05 |
3.9 |
3 |
1.89 |
|
Horseshoe Crab Nursery Grounds |
Pak Nai |
SR1 |
>
10 |
>
10 |
>
10 |
1.7 |
|
|
Sham Wat Wan |
SR10 |
>
10 |
6.9 |
6.9 |
2.3 |
|
|
Tai O |
SR12 |
>
10 |
5.7 |
5.7 |
1.9 |
|
|
Yi O |
SR14 |
>10 |
5.6 |
5.1 |
1.6 |
|
|
Sha
Lo Wan |
SR18 |
>
10 |
7.65 |
7.65 |
3.1 |
|
|
Tong Fuk Miu Wan |
SR33 |
6.6 |
2.85 |
2.1 |
5.9 |
|
|
Tung Chung Bay |
SR39 |
>
10 |
7.8 |
7.8 |
6.6 |
|
Protection Zone |
Chinese White Dolphin Protection Zone in
Mainland Waters |
SR11 |
>10 |
>10 |
>10 |
4.2 |
|
|
|
SR11a |
>10 |
9.15 |
8.25 |
1.9 |
|
|
|
SR11b |
9.15 |
7.2 |
6.45 |
1.9 |
|
Subtidal
Hard Bottom Habitat (coral) |
Southern side of South Soko |
SR31 |
0.370 |
1.9 |
1.9 |
1.9 |
Potential impacts to marine ecological
resources arising from the construction works may be divided into those due to
direct disturbances to the habitat and those due to perturbations to key water
quality parameters. Potential
impacts to marine mammals are discussed in Section
9.7. Impacts due to
construction wastewater discharge on marine ecology and marine mammals would
not be expected as it should satisfy the requirement of WPCO-TM effluent discharge standard (details refer to Part 2 Section 6.6.7). As discussed in Part 2 Section 6.6.9, minor water quality impacts will be expected
due to vessel discharges during construction, and therefore impacts on marine
ecology and marine mammals will not consider as a concern. Impacts associated with the proposed LNG
terminal are divided into those occurring during:
ˇP
Dredging, reclamation and
seawall modifications for the proposed LNG terminal, including dredging seawall
trenches, filling with sand and suitable fill and dredging for the seawater
intake and outfall pipes;
ˇP
Dredging for the approach
channel and turning basin;
ˇP
Construction of the jetty;
ˇP
Submarine gas pipeline
installation;
ˇP
Watermain
and cable installation; and,
ˇP
Relocation of the public
access pier.
Along the line of the seawalls the
existing marine sediments will be dredged to provide suitable foundations
covering an area of approximately 1.1 ha.
After completion of the seawall, the muds
within the reclamation sites will be partially dredged and then filled using
sand and/or public fill.
It should be noted that the reclamation
works at South Soko for the LNG terminal are of
relatively small scale and it is expected to be approximately 0.6 ha. Impacts to the marine ecological
resources potentially arising from dredging and reclamation at South Soko are summarised in Table
9.4 and discussed in further detail below.
Table 9.4 Summary
of Potential Construction Phase Impacts associated with Dredging and
Reclamation for the LNG terminal at
|
Nature of Impact |
Marine Habitat Affected |
Location |
Potential Impact |
|
Habitat Loss |
Subtidal Soft Bottom Habitat |
Sai Wan |
Permanent
loss of approximately 0.6 ha of seabed due to reclamation and along 150m long
margin of seawall modification works |
|
|
Tung
Wan |
Permanent
loss of seabed at the margin of 465 m long seawall modification works |
|
|
|
Subtidal Hard Bottom Habitat |
Sai Wan |
Permanent
loss of approximately 190 m of subtidal artificial
seawall coastline inside the reclamation area, and along 150 m long margin of
seawall modification works |
|
|
Tung
Wan |
Permanent
loss of approximately 245 m subtidal natural rocky
and 220 m artificial seawall coastline covering 1.1 ha |
|
|
|
Intertidal Natural Rocky Shore |
Tung
Wan |
Permanent
loss of approximately 245 m natural rocky shore |
|
|
Intertidal Artificial Shore |
Sai Wan |
Permanent
loss of approximately 190 m of artificial shore inside the reclamation area,
and along 150 m long margin of seawall modification works |
|
|
Tung
Wan |
Permanent
loss of approximately 220 m of artificial shore |
|
|
|
Intertidal Sandy Shore |
Sai Wan |
Permanent
loss of approximately 35 m of sandy shore |
|
Short term Changes in Water Quality |
Subtidal Soft Bottom Habitat |
Sai Wan |
Potential
smothering and burial of benthic organisms during dredging |
|
Tung
Wan |
Potential
smothering and burial of benthic organisms during dredging |
||
|
|
Subtidal Hard Bottom Habitat |
Sai Wan |
Potential
water quality impacts on subtidal organisms |
|
|
Tung
Wan |
Potential
water quality impacts on subtidal organisms |
|
|
|
Intertidal Natural Rocky Shore |
Sai Wan |
Potential
water quality impacts on intertidal organisms |
|
|
Tung
Wan |
Potential
water quality impacts on intertidal organisms |
|
|
|
Intertidal Sandy Shore |
Sai Wan (including Pak Tso Wan) |
Potential
water quality impacts on intertidal organisms |
|
|
|
Tung
Wan |
Potential
water quality impacts on intertidal organisms |
The
Project will involve the direct loss and temporary disturbance of marine
habitats.
Within
the reclamation footprint in Sai Wan, impacts will be
due to the smothering and burial of organisms during filling, or removal of
organisms during dredging. Dredging
would also be required for forming the foundations during seawall modification
works, which may also directly affect the margins of seabed at the base of
existing seawalls and rocky shore. These impacts are an unavoidable consequence
of the project and would occur during dredging and filling operations associated
with the reclamation works for the terminal.
Findings
from a literature review, supplemented by focussed field surveys, indicate that
the benthic assemblage within, and in the vicinity of, the reclamation were
dominated by polychaetes and characterised by similar
species diversity and dry season biomass as elsewhere in Hong Kong. The wet and dry season biomass of the
benthic assemblage at South Soko was comparatively
higher than most of the areas in Southern Waters, except Hei
Ling Chau, but lower than that of North-western Hong
Kong Waters. All of the species
recorded occur frequently in Hong Kong and no rare species were observed, with
the exception of the amphioxus Branchiostoma belcheri in Tung Wan. This species has been recorded at
several sites in Hong Kongˇ¦s eastern waters. It occurred in low numbers in Tung Wan
on the east side of South Soko. As a result of the presence of this
species, the assemblages at Tung Wan were regarded as being of medium
ecological value. All other areas
were regarded as being of low - medium ecological value.
Branchiostoma belcheri
is recognised as a species of high conservation interest in the region. As a result of its presence in Tung Wan,
the LNG terminal layout was modified as part of the design process so as to
largely avoid all permanent loss of subtidal soft
bottom habitat in this bay (see Part 2
Section 2 ˇV Consideration of South Soko Terminal Alternatives for details). Potential permanent loss of soft bottom
habitat would be limited to only the margins of seawall modification
works. These works would involve
modifications to existing areas of subtidal hard
bottom habitats which are habitats which are not considered important to Branchiostoma. Permanent subtidal
soft bottom habitat loss in Tung Wan, would therefore be confined to a thin
strip near the base of the existing sloping armour rock shoreline. According to the limited information
available from the literature review on the ecology of amphioxus, it was
reported that this species (Branchiostoma) prefers deeper waters of between 5 ˇV 8 m
depth. The potential loss of
shallower areas at the margin of the seawall slopes therefore may not be as
important habitat for Branchiostoma
than the deeper areas of the bay.
In conclusion, permanent loss of subtidal soft
bottom habitat in Tung Wan, has almost entirely been avoided at the design
stage of the LNG terminal and is therefore not expected to have unacceptable
impacts on amphioxus (Branchiostoma).
Reclamation
in Sai Wan bay will result is loss of approximately
190 m of subtidal artificial seawall coast covering
an area of approximately 0.6 ha.
Based on underwater dive survey findings, reclamation along this section
would result in the loss of sparse, isolated and scattered colonies of one hard
and one gorgonian seawhip coral species, which are
common and widespread in Hong Kong.
Seawall
modification works in Tung Wan will result in the loss of approximately 220 m
of subtidal artificial seawall and approximately 245
m of subtidal habitat along natural rocky coastline
in all covering a total area of approximately 1.1 ha. No corals were found on the artificial
seawall in this bay during dive surveys.
Along the natural rocky shore, seawall modification works would result
in the loss of a sparse and scattered, low cover and low diversity (7 species)
assemblage of common hard corals of low ecological value. Owing to their scarcity and limited
ecological value, the loss of these corals, which are well represented in coral
communities across Hong Kong, is not considered to be unacceptable.
The
assemblages on hard bottom habitat within the South Soko
reclamation area and seawall modification works area will be lost through the
burial of organisms present there.
These impacts are an unavoidable consequence of the Project and would
occur during dredging and filling operations associated within the reclamation
works and during works to modify seawalls.
Rubble
mound and/or armour rock/concrete armour seawalls will be used mostly along the
reclamations and will provide approximately 280 m of habitat at Sai Wan and approximately 360 m at Tung Wan for subtidal organisms to colonise. It has been demonstrated that marine
organisms have recolonised such seawalls after
construction ([7])
([8]). It is anticipated that similar
assemblages will settle on and recolonise the newly
constructed seawalls, as environmental conditions of that area would be similar
to the existing conditions that have allowed the growth of subtidal
organisms.
The
revised engineering layout for the terminal has reduced impacts on natural intertidal habitats by ensuring that the reclamation will
be along existing artificial seawall shoreline, thereby reducing the loss of
natural intertidal habitats. However, a loss of a small amount of
natural intertidal habitat would be inevitable due to
the seawall modification works.
Loss
of natural intertidal habitat will occur at Tung Wan
with the loss of approximately 245 m of medium ecological value natural rocky
shore. In addition, part (35 m) of
the sandy shore at Sai Wan, which has low ecological
value, will also be lost. The sandy
beach at Pak Tso Wan which was reported as
ˇ§importantˇ¨ ([9]),
is of medium ecological value and will not be directly affected by the
development.
As
stated above, most of the intertidal habitat loss at
South Soko will affect the artificial coastline. At Sai Wan and
Tung Wan, approximately 340 m and 220 m of low ecological value artificial
shoreline will be lost, respectively.
These
intertidal habitats will be replaced by artificial
seawalls. The artificial seawalls
can, over time, support similar assemblages of intertidal
fauna and flora. Organisms present
on intertidal shores in Hong Kong rely on larval
settlement for recruitment.
Assuming that there is a regular supply of larvae brought to the area, recolonisation of new seawalls will occur. The design of the seawall is important
in determining the extent to which the community re-establishes post
reclamation. The more heterogeneous
the seawall, the more diverse a community the habitat can support.
Although
the seawall modification works will result in the loss of approximately 280 m
of natural intertidal habitats (approximately 245 m
of rocky shore and 35 m of sandy shore), the severity of the impact is reduced
by the provision of sloping ecologically enhancing seawalls (approximately 360
m at Tung Wan and 90 m at Sai Wan). The sloping seawalls are all expected to
be of rubble mound/rock or concrete armour design.
The
construction of the reclamations for the terminal will involve dredging of the
sediments within the reclamation site and along the line of the seawalls and
filling of the reclamations using sand and public fill. The modelling works have analysed SS
dispersion from dredging of the reclamation site in the case that some marine muds have to be removed (Part 2 Section 3).