9
marine
Ecology
9.1
Introduction
9.1.1
The assessment of potential
impacts on marine ecology arising from the Project construction and operational
activities is presented in this section, in accordance with Clause 6.5.6 of the
EIA Study Brief. In general, the boundary
of the study area is 500 m from either side of the proposed reclamation
area. The study area, as shown in Figure
8.1, comprises existing urbanised reclaimed land and proposed new reclamation
near the existing coastline at Wan Chai.
9.2
Environmental Legislation,
Policies, Plans, Standards and Criteria
9.2.1
This section makes reference
to the following guidelines, standards, documents and HKSAR Government
ordinances and regulations when identifying habitats and species of ecological
importance, evaluating and assessing potential impacts of the proposed
development on the ecological resources in and around the study area:
·
Town Planning Ordinance
(Cap. 131);
·
Marine Parks Ordinance (Cap.
476) and associated subsidiary legislation;
·
Waterworks Ordinance (Cap.
102);
·
Marine Fish Culture
Ordinance (Cap. 353);
·
Fisheries Protection
Ordinance (Cap. 171) and its subsidiary legislation, the Fisheries Protection
Regulations;
·
Sites of Special Scientific
Interest (SSSIs) Register;
·
Hong Kong Planning Standards and Guidelines (HKPSG) Chapter 10, “Conservation”;
·
Works Branch Technical
Circular No. 24/94 (Planning, Environmental and Lands Branch Circular No. 3/94)
on Tree Preservation;
·
Works Branch Technical
Circular No. 4/97 (Planning, Environment & Lands Branch Technical Circular
No. 1/97), Guidelines for Implementing the Policy on Off-site Ecological
Mitigation Measures; and
·
Environmental Impact
Assessment Ordinance (Cap. 499) and the associated Technical Memorandum on
Environmental Impact Assessment Process (EIAO-TM), Annex 8 and Annex 16.
9.2.2
This section also makes
reference to the following international conventions:
·
Convention on the
Conservation of Migratory Species of Wild Animals (the “Bonn Convention”),
which requires parties to protect listed threatened or endanger migratory species
occurring within their boundaries;
·
United Nations Conventions
on Biodiversity (1992);
·
Convention on International
Trade in Endangered Species of Wild Fauna and Flora (“CITES”);
·
The PRC National Protection
List of Important Wild Animals;
·
International Union for Conservation of Nature
and Natural Resources (IUCN) Red Data Books.
9.3
Description of the
Environment
9.3.1
Under the Water Pollution
Control Ordinance (Cap. 358), the Victoria Harbour is
within the gazetted Victoria Harbour Water Control Zone. The EPD water quality monitoring results for
the study area showed that the marine water was generally turbid (1.5 - 4.0
NTU), low in dissolved oxygen (3.6 – 5.4 mg L-1), rich in inorganic
nutrients (annual mean total nitrogen 1.2 mg L-1 and annual mean
total phosphorus 0.11 mg L-1), and high in E. coli (22,733 – 24,000 cfu per 100 mL)
and faecal coliforms (4,333 – 44,000 cfu per 100 mL) (EPD, 1998).
Soft Bottom Benthos
9.3.2
The seabed is largely
composed of highly contaminated, hypoxic / anoxic, marine fine silt-clay
sediments. In a previous benthic survey,
Thompson and Shin (1983) took grabs from four stations in the study area. This revealed that the silt-clay percentage
ranged 20% - 40%, 40% - 60% and 60% - 80% at the four stations. The marine sediment in the study area,
according to EPD’s monitoring results, is largely
anaerobic and toxic with high COD (28,000 – 113,000 mg kg-1), high
total carbon (0.4 – 1.0% w/w), total volatile solids (6 – 9% w/w), ammoniacal nitrogen (10 - 63 mg L-1) and total
sulphide (4 – 530 mg kg-1) (EPD, 1998). The high organic matter is mainly derived
from sewage, commercial and industrial discharge.
9.3.3
Benthic assemblages in the
study area are typically of low diversity and abundance and community structure
is largely dictated by organic pollution from sewage discharges (Thompson and
Shin, 1983). As only a limited number of
hypoxia tolerant species can survive the bottom conditions within the study
area region, fauna is dominated by opportunists such as bivalves and polychaetes (Morton and Morton,
1983; Thompson and Shin, 1983). Dominant
polychaetes include Minuspio cirrifera and the best-known marine
organic enrichment indicator Capitella capitata. These polychaetes may be indicators of moderate and severe
organic pollution, respectively (Thompson and Shin, 1983). The moderately pollution tolerant bivalve Tapes philippinarum
was also dominant (Thompson and
Shin, 1983).
9.3.4
Field surveys of soft bottom benthos were conducted between
1996 to 1997 as part of the EPD Study, SSDS Stage I Baseline Monitoring and
Performance Verification. A
sampling station for this monitoring work was located within the Victoria Harbour on the Sheung
Wan side of Central Reclamation Phase I.
Grab samples collected were composed mainly of polychaetes,
molluscs and crustacean. This result indicated that the number of
soft-bottom benthos collected was low compared to other studies in Hong Kong.
9.3.5
Few recent ecological
studies have been conducted in the study area, and those that have usually
determined its polluted and / or contaminated nature using single species or
indicator groups (for examples, barnacles, Chan et al., 1990; Rainbow and Smith, 1992; Blackmore,
1999; fish, Kwan, 1999; Perna viridis,
Nicholson, 1999).
9.3.6
A recent field survey of
soft bottom benthic organisms was conducted in 1996 at the seabed within the Victoria Harbour at
the Central District (Atkins China Ltd. 1999).
This field survey indicated that the soft bottom marine environment in
the Victoria Harbour was polluted and lacked of macro-invertebrate community. Owing to the poor water quality in the study
area (Thompson & Shin, 1983; Shin, 1998) and the proximity of the past
field survey site, benthic assemblages in the WDII study area are likely to be
similarly impoverished and lack of macro-invertebrate.
Intertidal
9.3.7
The coastline found on the
northern part of the Kellett Island is the only natural coastline within the study area. The other existing coastline consists of
reclaimed land, breakwaters and sloping as well as blockwork seawalls.
9.3.8
A field survey was conducted
in August 2000 to identify the species composition at the natural coastline on Kellett Island. The natural coastline was visited by a marine
ecologist and the marine organisms encountered on the shore were identified to
the species level (or to genus level, at minimum). The natural coastline on Kellett Island is
a typical sheltered rocky shore with little strong-waves crashed upon it. The field survey indicated that the
assemblages were of sheltered rocky shore communities with high quantities of
Top shell, Monodonta austrailis,
dominating the lower shore and Periwinkles, Nodilittorina
millegrana, dominating the upper shore.
Other intertidal species including Stalked Barnacle, Pollicipes mitelia, Acorn Barnacle, Tetraclita squamosa, Common Chiton, Liolophura japonica and Limpet, Cellana toreuma were occasionally
observed. No rare
species nor species of conservation value were observed in the present
survey. The marine species found in the
study area by the present study and other studies are summarised in Appendix
9.1.
9.3.9
Where seawall / or rockfill
colonisation has taken place, flora and fauna present are largely restricted to
encrusting sessile organisms such as bivalves (Morton and Morton, 1983; Lee and
Morton, 1985). Other molluscs include
the common neogastropod, Thais clavigera and
the pollution-tolerant bivalve Perna
viridis (Morton and Morton, 1983; Lee, 1985; Lee and Morton, 1985). Encrusting crustaceans include barnacles, Balanus spp., Tetraclita squamosa and Capitulum
mitella (Morton and Morton, 1983) and the ubiquitous mobile isopod Ligia exotica (Morton and Morton,
1983). Flora is mostly restricted to
algae that are either organic or nutrient enrichment indicators such as Ulva spp. and Cladophora (Morton and Morton, 1983; Ho, 1987;
Moore, 1990). A recent field survey
conducted in the Victoria Harbour near the Central District noted that for the typically rocky shore
species that were found on the seawall, their development and physiology were
affected by water-borne pollutants (Atkins China Ltd., 1999).
Commercial Fisheries
9.3.10 A review of relevant literature revealed that there are no sensitive
ecological receivers within the study area.
Important fish nursery areas (Agricultural and Fisheries Department,
1998) are not present and the nearest mariculture zones are distant being
located in the eastern waters at Tung Lung Chau and the western waters at Ma
Wan (over 11 km and 14 km from the proposed reclamation, respectively).
9.3.11 The most recent trawl and bait-trap surveys conducted in the study area
and the surrounding area in 1998 caught various fish; species caught in the
study area includes Sebasticus marmoratus
and Siganus oramin (Albert Leung,
Boris Kwan personal communication). The
catches are generally of low economic value.
The fish species found in the study area are summarised in Appendix 9.1.
Marine Mammals
9.3.12 Marine mammals are often sighted in Hong
Kong waters.
However, literature review has shown that there were no sightings of
marine mammals within the study area. The nearest area where sighting of marine mammals, the Chinese
White Dolphin, Sousa chinensis was to
the east of Green Island. Therefore, the study area cannot be regarded
as of importance to the dolphin.
Others
9.3.13 There are no corals in the study area and the nearest are located at
Green Island, Junk Bay and Tung Lung Chau, about 6 km to the east and 11 km to
the west, respectively (Denise McCorry personal communication). An assessment of the effects of backfilling
in Mirs Bay assumed that prolonged turbidity and a sustained sedimentation rate of
0.2 kg m-2 per day was damaging to corals (Binnie, 1992).
Ecological Sensitive Receivers
9.3.14 As stated in Section 9.3.1 to 9.3.13, there are no ecological sensitive receivers, such as SSSIs, Fish
Culture Zones and Marine Parks and / or Reserves and other areas of ecological importance or
conservation interest, in and within the vicinity of the study area. As the proposed development will include new
reclamation, far field ecological sensitive receivers have been identified. These potential off-site ecological sensitive
receivers include coral area located at Green Island, Junk Bay and
Tung Lung Chau, Ma Wan Fish Culture Zone and open fishery area near Kau Yi Chau.
Ecological Importance
9.3.15 Based on the available literatures and discussion presented above, the
current ecological assessment shows that the marine ecological resources
present within the WDII study area are considered to be of low ecological
value. This has been determined on the
basis of the considerations in accordance with the EIAO-TM Annex 8 Table 2
criteria and is shown in Tables 9.1, 9.2 and 9.3.
Table
9.1 Criteria and Evaluation of the
Soft Bottom Benthic Habitats
|
Criteria
|
Evaluation
|
|
Naturalness
|
Soft bottom benthic habitats have been subjected
to extensive disturbance through high pollution load.
|
|
Size
|
The area to be dredged and reclaimed is
approximately 27 hectares.
|
|
Diversity
|
The species diversity is low.
|
|
Rarity
|
No rare species found.
|
|
Re-creatability
|
The soft bottom benthic habitats cannot be
recreated on site.
|
|
Fragmentation
|
Not applicable
|
|
Ecological linkage
|
The present habitats are not
functionally linked to any highly valued habitat in close proximity.
|
|
Potential value
|
The potential value is low.
|
|
Nursery ground
|
Not applicable
|
|
Age
|
Not applicable
|
|
Abundance / Richness of wildlife
|
Low
|
Table 9.2 Criteria and
Evaluation of the Intertidal Habitats (Natural)
|
Criteria
|
Evaluation
|
|
Naturalness
|
Intertidal habitat at northern Kellett Island
is natural habitat.
|
|
Size
|
The natural intertidal shoreline is
approximately 67 m.
|
|
Diversity
|
The species diversity is low.
|
|
Rarity
|
No rare species found. But it is worth noting that this coastline
is one of the remaining natural habitats on the north shore of Hong Kong Island.
|
|
Re-creatability
|
The intertidal habitats can be recreated.
|
|
Fragmentation
|
Not applicable
|
|
Ecological linkage
|
The present habitats are not
functionally linked to any highly valued habitat in close proximity.
|
|
Potential value
|
The potential value is low since no rare
species nor species of conservation value were
found.
|
|
Nursery ground
|
Not applicable
|
|
Age
|
Not applicable
|
|
Abundance / Richness of wildlife
|
Low to medium
|
Table 9.3 Criteria and
Evaluation of the Intertidal Habitats (Artificial)
|
Criteria
|
Evaluation
|
|
Naturalness
|
Intertidal habitats are man-made areas and
some of which mimic natural rocky shore.
|
|
Size
|
Approximately 150 m (length of sloping face =
300 m) of rock armour seawall will be removed and approximately 810 m of rock
armour sloping seawall, 2,800 m of vertical seawall and 440 m of sloping
seawall (granite facing) will be subsumed by reclamation and permanently
lost.
|
|
Diversity
|
The species diversity is low.
|
|
Rarity
|
No rare species found.
|
|
Re-creatability
|
The intertidal habitats can be recreated.
|
|
Fragmentation
|
Not applicable
|
|
Ecological linkage
|
The present habitats are not
functionally linked to any highly valued habitat in close proximity.
|
|
Potential value
|
The potential value is low.
|
|
Nursery ground
|
Not applicable
|
|
Age
|
Not applicable
|
|
Abundance / Richness of wildlife
|
Low
|
9.4
Assessment Methodology
9.4.1
Evaluation and assessment of
potential impact on ecological resources are conducted in accordance with the
criteria and guidelines specified in Annex 8 and Annex 16, respectively, of the
EIAO-TM.
9.4.2
The significance of impacts
is ranked as “minor”, “moderate” or “severe” based on the criteria shown in
Table 9.1. The description
of the ranking are as below:
9.4.3
Minor - Impacts to species or groups are assessed as
“minor” if the predicted impact would result in a slight, and / or short-term
reduction in the local population numbers or geographic distribution of a
species or group, but the species or group is predicted to recover from the perturbation
with no-long term adverse impacts.
Impacts to habitat are assessed as “minor” when the habitat is widely
distributed locally and that no rare, protected or conservation importance
species are found in the habitat.
9.4.4
Moderate – Impacts to species or groups are considered
“moderate” if the predicted impact would result in probably non-recoverable and
/ or long-term reduction in population numbers.
However, the species in question should be considered widely distributed
or common, and abundant on a local, regional or global scale. Impacts to habitat are assessed as ‘moderate”
if the habitat is of limited local or regional distribution or declining in
extent and that the habitat has a potential of supporting fauna and / or fauna
of conservation or regulatory importance.
9.4.5
Severe – Impacts to species or groups are judged to
be “severe” if the predicted impact has an adverse effect on species or groups
which are rare, protected or of conservation importance locally, regionally, or
globally. Impacts to habitat are
considered to be “severe” if the habitat in question is of limited local or
regional distribution or declining in extent and that it contains rare,
protected or conservation importance species or generally considered by the
scientific community to be of local, regional or global importance to the
support of wild fauna.
9.4.6
If impacts on ecological
resources are found to be significant (that is, moderate or severe), mitigation
measures will be recommended in accordance with the EIAO-TM. Impact mitigation will be sought in the
following priority: avoidance, minimisation, on-site compensation and off-site
compensation. Impact avoidance generally
consists of modifications to the preferred development options, but may in some
extreme cases require abandonment of the project. Impact minimisation includes any means of
reducing the scope or severity of a given impact, for example, through timing
of construction programme, modification in the design or ecological restoration
of disturbed areas following the completion of works. Impact compensation will be recommended if
the effect on a given species or habitat is irreversible and attempts will be
made to compensate it elsewhere, for example, enhancement, creation of suitable
habitats or recreation of the habitat.
Compensation can be on-site or off-site.
Off-site compensation will only be recommended if all possible
mitigation measures have been investigated and it will be conducted in
accordance with the Works Branch Technical Circular No. 4/97.
9.5
Identification of
Environmental Impacts
9.5.1
The total volume of dredged
sediment is estimated to be approximately 0.99 Mm3. The estimated volume of contaminated dredged
sediment is approximately 0.6 Mm3. The dredged contaminated sediment shall be
disposed of at the East Sha Chau
Contaminated Mud Pits that are designated for the disposal of contaminated mud
in Hong Kong. The detail of ecological impacts and the
mitigation measures of disposal material were described in the relevant EIA
studies on the disposal of contaminated mud in the East Sha
Chau Marine Borrow Pits and would not be addressed in
this EIA Report.
9.5.2
Impacts to marine ecological
resources may arise during the construction and operational phases. The impacts may be derived from direct
disturbance to the habitat and indirect disturbance through changes to key
water quality parameters.
Construction Phase
9.5.3
The potential marine
ecological impacts arising from the Project construction activities may
include:
·
direct impacts of habitat
loss and the associated marine species due to reclamation; and
·
indirect impacts to the habitat and the associated fauna due to changes in water
quality.
Operation Phase
9.5.4
The potential marine
ecological impacts arising from the Project operational activities may include
impacts from the proposed
reclamation due to changes in tidal flow and the hydrographic regime of
the harbour.
9.6
Prediction and Evaluation of
Environmental Impacts
Construction Phase (Direct Impact)
9.6.1
The dredging and reclamation works will result in the permanent loss of
approximately 28.5 hectares of soft bottom benthic habitat. Approximately 1,110m of rock armoured sloping seawall and 440m of sloping seawall (with
granite facing) will be permanently lost due to reclamation or removal of
existing breakwaters (Figure 9.1).
Approximately 2,800m of existing vertical seawall will also be lost
during the reclamation, but some 1.5 km of new caisson seawall and 1.3 km of
new blockwall seawall will be constructed. These seawalls are expected to provide habitat
of similar ecological value to that of the existing blockwall
seawalls that constitutes the main part of the reclaimed intertidal
habitat. Since the benthic community and
intertidal community in the study area are of low
ecological value, only minor impacts are anticipated from the reclamation works. The existing natural shoreline
at Kellett Island of approximately 67m will remain intact during construction.
9.6.2
The present construction
adopts an approach where permanent and temporary seawalls will first be formed
to enclose each phase of the reclamation and filling will be undertaken behind
the seawalls. The sediment plume is
effectively contained within the reclamation area, minimising the loss of fine
sediments to the adjacent water bodies.
Construction Phase (Indirect Impact)
9.6.3
Indirect impacts on the
marine ecology are associated with the sediment release during the construction
works. Potential impacts include:
Elevation of Suspended Solids (SS):
9.6.4
Sessile organisms within the
benthos will be susceptible to the effects of increased sediment loads. Effects can be lethal or sublethal through
reduction in reproductive potential due to stress incurred by constantly having
to flush out the depositing material.
The effects of sedimentation on organisms will also depend on other
factors, such as an organism’s tolerance, growth orientation of sessile
organisms and water movement.
9.6.5
Based on the prediction of
the construction phase water quality modelling, potential water quality impact
due to elevation of suspended solids would occur along waters at Central, Wan
Chai and Causeway Bay Typhoon Shelter (see Section 5). As the intertidal habitats in these areas are
of low ecological value and the intertidal assemblages is expected to
recolonise these areas after the construction activities, only minor impact due
to elevation of SS is anticipated.
Reduction of Dissolved Oxygen (DO):
9.6.6
The relationship between SS
originated from construction works and DO are complex, with increased SS in the
water column combining with a number of other effects to reduce DO concentration
in water. Elevated SS (and turbidity)
reduces light penetration, lowers the rate of photosynthesis of phytoplankton
and, thus, lowers the rate of oxygen production in the water column. This has a particularly adverse effect on the
eggs and larvae of fish, as high levels of oxygen in the water are required for
growth due to high metabolic rates. DO
depletions will most likely affect sessile organisms as they cannot move away
from the affected areas. As the soft bottom benthic habitats and the
associated communities in the study area are of low ecological value, only
minor impact due to reduction of dissolved oxygen is anticipated.
Elevation of Nutrients:
9.6.7
High levels of nutrients in
seawater can cause rapid increases in phytoplankton often to the point where an
algal bloom occurs. An intense bloom of
algae can lead to sharp decreases in the levels of DO in the water as dead
algae fall through the water column and decompose on the bottom. Anoxic conditions may result if DO concentration
is already low or is not replenished.
This may result in mortality to marine organisms due to oxygen
deprivation. As the soft bottom benthic habitats and the associated communities
in the study area are of low ecological value, only minor impact due to
elevation of nutrients is anticipated.
Operation Phase
9.6.8
Impacts to marine ecological
resources could potentially occur if the shape of the reclamation causes a
change on the hydrodynamic regime of the harbour.
Impacts of this nature could lead to increased seabed current speeds
that may cause seabed scour, thus impacting subtidal assemblages. Conversely, the current speeds may drop in
some areas affecting flushing and water exchange of these areas. Inadequate flushing could lead to reduction
in dissolved oxygen and increase in nutrients and consequent impacts to marine
ecological resources.
Impact Evaluation (Construction Phase)
9.6.9
The dredging and reclamation
works will result in the permanent loss of approximately 28.5 hectares of soft
bottom benthic habitat and approximately 4,350 m of artificial intertidal
habitat. Since the benthic community and
intertidal community in the study area are of low ecological value, only minor
impact is anticipated. Moreover, approximately
2 ha (1.5 km in length and 13 m in depth) of caisson seawall and 1.2 ha (1.3 km
in length and 9.4 m in depth) of blockwork seawall will
be built. It is anticipated that such
seawalls are expected to provide habitat of similar ecological value to that of
the blockwork seawalls that constitutes the main part
of the reclaimed intertidal habitat. Similar intertidal
flora and fauna existing at present are expected to recolonise the new seawall.
9.6.10 Impact to the far field ecological sensitive receivers including the
coral areas located in the vicinity of Green Island,
Tung Lung Chau and at Junk Bay, Ma Wan Fish Culture Zone and open fishery area near Kau Yi Chau, is
not anticipated. Elevations of SS at
these locations were predicted to be less than 2.3 mg L-1 under the
worst case scenario (see water quality assessment in Section 5). An elevation of this magnitude is very small
and the total SS level is compliant with the WQO for these areas. Thus, it is expected that unacceptable
impacts to these areas arising from elevated SS levels will not occur.
9.6.11 Based on the prediction of construction phase water quality modelling,
impacts to benthic and intertidal assemblages immediately outside of the
reclamation site are expected to occur during the construction phase as the
elevation of SS is predicted to be 20 mg L-1 (see water quality
assessment in Section 5). However, since
the seabed community and intertidal community in the vicinity of the study area
in the Victoria Harbour are of low ecological value and in view of the impact of suspended
solids elevation is temporary, only minor impact is anticipated.
Impact Evaluation (Operational Phase)
9.6.12 The hydrodynamic modelling (Section 5) has predicted that the
reclamation of WDII will have minimal impact on the hydrodynamic regime of the
study area and there will be no insurmountable hydrodynamic impacts. The flow speed distributions within the Victoria Harbour
before and after the implementation of the WDII Project are very similar. The reclamation will only cause slight change
in the prevailing currents in the study area.
Therefore, only minor impact due to changes of tidal discharges and
current patterns is anticipated.
9.6.13 There are no planned construction activities or alteration to the
natural shoreline on the Kellett Island for the present scope of the Project.
However, a breakwater structure will be built north of the shoreline
partially enclosing the adjacent seawater.
A main concern of the breakwater to the species community is the
potential reduction of flushing in the partially enclosed water. Based on the prediction of operational phase
water quality modelling, the water quality inside the Kellett
Island Marina is similar to the water immediately outside the breakwater and only
minor impact is anticipated.
Overall
Impact
9.6.14 Based upon the discussion between Sections 9.6.1 and 9.6.13, the marine
ecological impact associated with the WDII development (essentially during the
construction phase) is considered to be minor.
A summary of impact evaluation is presented in Table 9.4.
Table 9.4 Summary of Impact Evaluation
|
Developmental Phase
|
Potential Impact
|
Impact Evaluation
|
|
Construction
Phase
|
Loss
of soft bottom habitat (approximately 28.5 hectares) and artificial intertidal habitat (approximately 4,350 m).
|
Minor
|
|
Elevation
of SS at the far field ecological sensitive receivers
|
Minor
|
|
Elevation
of SS in the Victoria Harbour
|
Minor
|
|
Operational
Phase
|
Changes
in tidal discharges and current patterns in the Victoria Harbour
|
Minor
|
|
Reduction
of flushing to the natural shoreline on the Kellett Island
|
Minor
|
|
Overall
Impact
|
Minor
|
9.7
Mitigation of Adverse
Environmental Impact
9.7.1
No mitigation measure is
required since no unacceptable ecological impact is anticipated.
9.8
Environmental Monitoring and
Audit
9.8.1
Ecological monitoring and
auditing will not be required.
9.9
Conclusion
9.9.1
Literature reviews of
existing information supplemented with the results of recently undertaken field
surveys on marine ecological resources indicate that the intertidal habitats
and soft benthic habitats within the Study Area are of low ecological value. There are no ecological sensitive receivers,
such as SSSIs, Fish Culture Zones and Marine Parks and
/ or Reserves and other areas of ecological importance or conservation interest, in and within the
immediate vicinity of the study area.
9.9.2
The dredging and reclamation works will result in the permanent loss of
approximately 28.5 hectares of soft bottom benthic habitat. Approximately 1,110m of rock armoured sloping seawall and 440m of sloping seawall (with
granite facing) will be permanently lost due to reclamation or removal of existing
breakwaters. Approximately 2,800m of
existing vertical seawall will also be lost during the reclamation, but some
1.5 km of new caisson seawall and 1.3 km of new blockwork
seawall will be constructed. These
seawalls are expected to provide habitat of similar ecological value to that of
the existing blockwall seawalls that constitutes the
main part of the reclaimed intertidal habitat. Since the benthic community and intertidal community in the study area are of low
ecological value, only minor impacts are anticipated from the reclamation works. Similar intertidal
flora and fauna existing at present are expected to recolonise
the new seawall.
9.9.3
Based on the prediction of
construction phase water quality modelling, impacts to benthic and intertidal
assemblages immediately outside the reclamation site are expected to occur
during the construction phase. However,
since the seabed community and intertidal community in the vicinity of the
study area are of low ecological value and in view of the impact of suspended
solids elevation is temporary, only minor impact is anticipated.
9.10
References
1. Agriculture and Fisheries Department (1998). Port Survey 96/97, Capture Fisheries
Division.
2. Atkins China Ltd. (1999). Central
Reclamation, Phase III, Studies, Site Investigation, Design and Construction.
Comprehensive Feasibility Study for Minimum Option: Final Key issues and
Initial Environmental Impact Assessment Report.
3. Binnie Consultant Ltd. (1992). South Mirs Bay
Borrow Area. IAR.
4. Blackmore, G.R. (1999). The importance of feeding ecology in
investigating accumulated heavy metal body burdens in Thais clavier (KUSTER)
(mollusca: neogastropoda: muricidae) in Hong Kong. PhD Thesis, Hong
Kong University.
5. Chan, H. M., Rainbow, P. S. and Phillips, D. J. H. (1990). Barnacles and mussels as monitors of trace
metal bio-availability in Hong Kong waters. Proceedings of the Second International Marine Biological Workshop: the
Marine Flora and Fauna of Hong Kong and Southern China 1986 (ed. B. Morton), 1268-39. Hong Kong: Hong Kong University
Press.
6. Environmental Protection Department (1998). Marine Water Quality in Hong Kong for 1997.
7. Ho, Y. B. (1987). Ulva lactuca (Chlorophyta, Ulvales) in Hong Kong intertidal
waters - its nitrogen and phosphorus contents and its use as a bioindicator of
eutrophication. Asian Marine Biology 4:
97-102.
8. Kwan, S. P.
(1999) Heavy metals in Hong Kong rabbitfish (Siganus canaliculatus).
M. Phil. Thesis, HKU.
9. Lee, S. Y. (1985). The population
dynamics of the green mussel, Perna
viridis, (L.) in Victoria Harbour, Hong Kong – dominant in a polluted environment. Asian Marine Biology 2: 107-118.
10. Lee, S. Y. and Morton, B. (1985).
The Hong Kong Mytilidae. Proceedings of the Second International Workshop on
the Malacofauna of Hong
Kong and Southern
China, Hong
Kong, 1983. (ed. B. Morton & D. Dudgeon), 49-76. Hong
Kong: Hong Kong University
Press, 1985.
11. Moore, P. G. (1990). Preliminary
notes on a collection of amphipoda from Hong
Kong. Proceedings of the Second International
Marine Biological Workshop: the Marine Flora and Fauna of Hong Kong and Southern China 1986 (ed. B. Morton), 503-14. Hong Kong: Hong Kong University
Press.
12. Morton, B. and Morton, J. (1983).
The Sea Shore Ecology of Hong Kong. Hong Kong University
Press.
13. Nicholson, S. (1999)
Cytological and physiological biomakers
in Perna viridis (Bivalvia: Mytilidae). PhD Thesis, HKU.
14. Rainbow, P. S. and Smith, B. D. (1992).
Biomonitoring of Hong Kong coastal trace metals by barnacles. Proceedings of the Third International
Marine Biological Workshop: the Marine Flora and Fauna of Hong Kong and Southern China 1989 (ed. B. Morton), 585-98. Hong Kong: Hong Kong University
Press.
15. Shin, P. K. S. (1998).
Biodiversity of subtidal benthic polychaetes in Hong Kong coastal waters. Proceeding
of the Third International Conference in the Marine Biology of the South China Sea: The Marine Biology of the South China Sea III 1996 (ed. B. Morton). Hong Kong University
Press.
16. Thompson, G. B. and Shin, P. K. S. (1983). Sewage Pollution and the Infaunal
Macrobenthos of Victoria Harbour, Hong Kong Journal of Experimental Marine
Biology and Ecology 67: 279-299.
Personal Communications:
Kwan,
S. P., World Wild Fund for Nature (WWF).
Leung, A., Agriculture, Fisheries and Conservation Department.
McCorry, D., PhD student, Hong Kong University.