Agreement
No. CE 72/2019 (EP) Environmental
Impact Assessment (EIA) Report for the New Contaminated Sediment Disposal
Facility to the West of Lamma Island July 2022 |
This Section presents an evaluation of the marine
ecological impact assessment associated with the construction and operation of
the proposed Project in accordance with Clause
3.4.4 of the EIA Study Brief. It
also summarises the key findings on the baseline ecological conditions, the
details of which are presented in Annexes 4A to 4E.
The criteria and scope for evaluating ecological impacts are laid out in
the Annexes 8 and 16 of the EIAO-TM and the
EIA Study Brief. Legislative requirements and evaluation criteria
relevant to this assessment are listed below. The details on each
are presented in Annex 4A.
n
Marine Parks Ordinance (Cap. 476)
and its Subsidiary Legislation;
n
Wild Animals Protection Ordinance
(Cap. 170);
n
Protection of Endangered Species of
Animals and Plants Ordinance (Cap. 586);
n
Town Planning Ordinance (Cap. 131);
n
Environmental Impact Assessment
Ordinance (Cap. 499) and the Technical Memorandum on Environmental Impact
Assessment Process under the Environmental Impact Assessment Ordinance
(EIAO-TM);
n
Environmental Impact Assessment
Ordinance (EIAO) Guidance Notes No. 6/2010, 7/2010 and 11/2010;
n
Hong Kong Planning Standards and
Guidelines Section 10 (HKPSG);
n
United Nations Convention on
Biological Diversity (CBD);
n
The Convention on International
Trade in Endangered Species of Wild Fauna and Flora of Wild Fauna and Flora
(CITES);
n
The International Union for
Conservation of Nature (IUCN) Red List of Threatened Species; and
n
Peoples’ Republic of China (PRC)
Regulations and Guidelines.
With reference to Clause 3.4.4.2 of the EIA Study Brief,
the Assessment Area for the purpose of the marine ecological impact assessment
shall be the same as that for water quality impact assessment, covering the
Southern Water Control Zone (WCZ) and Western Buffer WCZ as designated under
the WPCO. Also, some of the concurrent
projects are located close to the Victoria Harbour WCZ and the Assessment Area
is therefore extended to cover Victoria Harbour WCZ for cumulative
assessment.
Water depth at the
Assessment Area varies. In the East
Lamma Channel, water depth typically exceeds -20 mPD with exception of coastal
waters. In the West Lamma Channel (where
the proposed CMPs are located), water depth is generally less than -10 mPD at
water between Lamma and the Lantau Island.
Waters south of Lamma is generally deeper and exceeds -20 mPD. Compliance with the
WQOs is generally observed in most parameters at the selected monitoring
stations at the relevant WCZs, except for total inorganic nitrogen (TIN)
levels. A detailed description of the physical characteristics of
the marine environment of the Assessment Area is provided in Section
3.
Known important habitats and species for marine ecology within the Assessment Area include coral and benthic communities, FP, Green Turtle, as well as the potential South Lamma Marine Park. The ecological profiles and characteristics of these habitats and species are described in further detail below. Habitat map for marine ecology is provided in Figure 4.1.
A literature review was
conducted to review the baseline ecological conditions within the Assessment
Area and to identify information gaps to determine whether field surveys are
required to provide sufficient information for the ecological impact
assessment. Findings of this literature
review are presented in detail in Annex 4A.
Some of the baseline information for marine ecology of the Assessment
Area is available from other EIA studies conducted between 2008 and 2017, and
the latest information on marine mammals was collected up to March 2021 ([1]). The data sources provide up-to-date baseline
information on important ecological habitats or habitats with conservation
interest such as Marine Park, mangroves, habitats for FP, etc. of the
Assessment Area. Baseline survey of
these habitats is not considered necessary.
There are identified
data gaps with regards to the status of the subtidal habitat within the WL
Facility where no recent baseline information is available. In accordance with the requirements in Appendix C of the EIA Study Brief,
marine ecological surveys at selected habitats within the Assessment Area where
potential impact could occur and up-to-date baseline information is not present
were conducted to update the latest ecological conditions in these areas. Furthermore, to better understand the
occurrence, distribution and abundance of marine mammals especially FP in the
Study Area, focused marine mammal surveys within and in the vicinity of the
Study Area were also conducted. The
detailed methodology of the surveys is presented in Annex 4B. The survey findings are presented in detail
in the following sections.
Marine ecological
surveys were carried out between March and August 2021 and the survey schedule
is summarised in Table 4.1. The surveys were
conducted in both wet and dry seasons for species with seasonality, such as
subtidal infauna assemblage. Higher survey frequency was also conducted for species of interest, such
as marine mammals. The survey effort is considered appropriate
to meet relevant objectives of ecological baseline study for providing adequate
information for the impact assessment.
Table 4.1 Summary of Marine Ecological Survey Schedule
Survey |
Frequency |
Location |
Season & Date |
Coral Survey |
Once in
the survey period |
Qualitative
spot-dive and rapid ecological assessment (REA): 2 locations at Lamma and 1
location at Cheung Chau Drop
camera survey: 5 locations within the Study Area |
29 Jun
& 9 Jul 2021 |
Subtidal Benthos
Survey |
Once in
each of the dry and wet season |
7
locations within the Study Area |
Dry
season: 24 Mar 21 Wet
season: 17 May 21 |
Marine Mammal
Survey |
Once
per month between March and August 2021 (Peak and non-peak seasons of FP
occurrence) |
Marine
waters within and in the vicinity of the Study Area |
Peak
season: 18 Mar, 12 Apr, 5 May 21 Non-peak
season: 7 Jun, 16 Jul, 16 Aug 21 |
The weather was fine
and sea was generally calm during
the coral surveys. The underwater
visibility ranged between 0.1 m and 3 m and was generally poorer in deeper
region. REA surveys were conducted as
corals were present in all the three survey locations (Figure 2.1 of Annex 4B). The seabed composition was identified and the
coral species was recorded. Common and
widespread corals, including hard corals (9 species), ahermatypic hard corals
(2 species) and octocorals (5 species), were recorded in low percentage cover
(< 10%) at all the three survey locations.
Representative photographs of the seabed and coral conditions at the
survey transects are presented in Figures 4.2
and 4.3. Detailed results of the REA survey can be
found in Annex
4C.
For the five survey
locations for drop camera survey (Figure 2.1 of Annex 4B),
the seabed mainly consisted of silty mud and sandy substrates. Gorgonians were scarcely observed in very low
abundance at some of the survey locations.
It should be noted that due to limited underwater visibility, the
recorded gorgonians from the drop camera survey could not be identified to
genus/species level. Representative
photographs from the drop camera survey are presented in Figure 4.4. Detailed results of drop camera survey can be
found in Annex 4C.
The general substrata
and biological conditions along each transect noted during the qualitative spot
dive reconnaissance check & REA survey and drop camera survey are presented
in Table
4.2 and 4.3, respectively.
Table 4.2 Summary of Results of Qualitative Spot Dive Reconnaissance Check and REA Survey
Survey Location (see Figure 2.1 of Annex 4B) |
Depth |
Description |
|
Shallow |
Deep |
||
C1 |
-2 to -3 mCD |
-6 to -8 mCD |
The transect is located
at the southeastern coast of Cheung Chau.
The site was dominated by large and small boulders with <5% hard coral
coverage in both shallow and deep waters.
Octocoral was only found in deep water region with <10%
coverage. Hard coral Psammocora
profundacella was relatively common in the shallow water region while Cyphastrea serailia and Plesiastrea
versipora were uncommon.
Ahermatypic hard coral Balanophyllia sp. was relatively common
in the deep water region, and isolated colonies of hard coral Oulastrea
crispata and Bernardpora stutchburyi were found common in the deep
water region. Among the octocorals
found in the deep water region, Menella sp./ Paraplexaura sp.
and Echinomuricea sp. were relatively common. Other benthos had <10% coverage and
bryozoans were the most commonly recorded benthos, followed by sponges. |
C2 |
-2 to -4 mCD |
-6 to -7 mCD |
The transect is located
at the northwestern tip of Lamma Island. It is mainly covered by bedrock in
the shallow water region and large boulders in the deep water region, mixed
with some sandy substrates at both shallow and deep waters. Hard corals and octocorals were found in
both shallow and deep water regions with <10% coverage. Hard coral Bernardpora
stutchburyi, Porites sp. and
octocoral Menella sp. / Paraplexaura sp. were relatively common
in the shallow water region. Octocoral Menella sp. / Paraplexaura
sp was also relatively common in the deep water region, with occasional
observation of hard coral Bernardpora stutchburyi, ahermatypic hard
coral Tubastrea/ Dendrophyllia sp. and Balanophyllia sp., as
well as octocoral Echinomuricea sp..
Other benthos had <10% coverage, of which bryozoans were the most
commonly recorded benthos, followed by sponges. |
C3 |
-2 to -3 mCD |
-6 to -8 mCD |
The transect is at the
southwestern part of Lamma Island.
Both shallow and deep water regions are dominated by large boulders,
mixed with some sand, rubbles or bedrock.
Hard coral coverage was <5% in both shallow and deep water
regions. In the shallow water region,
hard corals Oulastrea crispata and Porites sp. were relatively
common. In the deep water region, hard
corals Psammocora haimiana, Psammocora profundacella, ahermatypic hard coral Tubastrea/
Dendrophyllia sp. and octocoral Dendronephthya sp. were commonly
encountered. Other benthos had <10%
coverage, of which bryozoans were the most commonly recorded benthos. |
Table 4.3 Summary of Drop Camera Survey Results
Survey Location |
Description |
D1 |
The seabed consisted of a
mixture of sandy bottom and silty mud.
A very low abundance of gorgonians was observed. No rare
species or species with conservation importance was observed. |
D2 |
The seabed consisted of
mainly silty mud substratum. A very
low abundance of gorgonians was observed. No rare species or species with
conservation importance was observed. |
D3 |
The seabed consisted of
mainly silty mud and a little sandy substratum. A worm was recorded in the drop camera
survey. No gorgonian, rare species or
species with conservation importance was observed. |
D4 |
The seabed consisted of
mainly sandy substrate. A very low
abundance of gorgonians observed. No
rare species or species with conservation importance was observed. |
D5 |
The seabed consisted of
mainly sandy substrate. A fish was
recorded in the drop camera survey. No
gorgonian, rare species or species with conservation importance was observed.
|
Overall, results of the
coral surveys indicated that the subtidal hard substrate within and in the
vicinity of the Study Area showed very limited sessile taxa. Common
and widespread corals, including hard coral, ahermatypic hard
coral and octocoral, were recorded in low percentage cover (< 10%)
at all the survey locations.
Subtidal
benthos surveys were conducted in the dry and wet seasons at seven locations, as shown in Figure 2.1 of Annex 4B, representative of the subtidal
soft-bottom habitats of the Study Area.
A total
of 271 individual organisms (3.2 grams in total) were collected from
the seven grab samples from the seven sampling locations during the
dry season survey. The specimens belong
to eight phyla with a total of 12 classes, 58 families
and 59 species identified. In terms of infaunal abundance, the
majority of organisms recorded were from the Phylum Annelida (~64%) and
Arthropoda (~17%). The species Apionsoma trichocephalus was
the most abundant species (total abundance = 22 individuals). In terms of
infaunal biomass, organisms from the Phylum Arthropoda contributed ~48% of the
total biomass recorded, followed by Annelida which contributed
~29%. No rare species or uncommon
species were recorded in the survey.
A total
of 317 individual organisms (2.1 grams in total) were collected from
the seven grab samples from the seven sampling locations during the
wet season survey. The specimens belong
to seven phyla with a total of nine classes, 50 families
and 71 species identified. In
terms of infaunal abundance, the majority of organisms recorded were from the
Phylum Annelida (~66%) and Arthropoda (~16%). Polychaete worms Maldanidae
spp. were found to be the
most abundant among all organisms (total abundance = 34 individuals). In terms of infaunal biomass, organisms from
the Phylum Annelida contributed ~42% of the total biomass recorded, followed
by Echinodermata which contributed ~27%. No rare species or uncommon species were
recorded in the survey.
Tables 4.4 and 4.5
provide a summary of the abundance, taxonomic richness, Pielou’s Evenness,
Shannon Diversity and biomass of infauna collected at each location in the dry
and wet seasons respectively. A complete set of raw data is presented in Annex 4D.
Table 4.4 Density and Indices of Richness, Evenness and Diversity of Infaunal Assemblages at the Sampling Locations for the Soft Bottom Habitat Surveys at the Study Area during the Dry Season
Survey
Location |
Abundance
of Infaunal Individuals |
Taxonomic
Richness (No. Families) per Site |
Taxonomic
Richness (No. Species) per Site |
Pielou’s
Evenness (J) |
Shannon
Diversity (H’) |
Total
Biomass (g wet weight) |
Mean
Biomass per Individual (g wet weight) |
B1 |
23 |
10 |
11 |
0.86 |
2.07 |
0.2930 |
0.0127 |
B2 |
108 |
28 |
37 |
0.90 |
3.27 |
1.4196 |
0.0131 |
B3 |
18 |
11 |
13 |
0.98 |
2.51 |
0.1770 |
0.0098 |
B4 |
27 |
13 |
15 |
0.86 |
2.34 |
0.1676 |
0.0062 |
B5 |
19 |
9 |
11 |
0.97 |
2.33 |
0.2603 |
0.0137 |
B6 |
39 |
19 |
21 |
0.93 |
2.82 |
0.3883 |
0.0100 |
B7 |
37 |
16 |
18 |
0.95 |
2.76 |
0.4632 |
0.0125 |
Table 4.5 Density and Indices of Richness, Evenness and Diversity of Infaunal Assemblages at the Sampling Locations for the Soft Bottom Habitat Surveys at the Study Area during the Wet Season
Survey
Location |
Abundance
of Infaunal Individuals |
Taxonomic
Richness (No. Families) per Site |
Taxonomic
Richness (No. Species) per Site |
Pielou’s
Evenness (J) |
Shannon
Diversity (H’) |
Total
Biomass (g wet weight) |
Mean
Biomass per Individual (g wet weight) |
B1 |
33 |
12 |
13 |
0.83 |
2.12 |
0.6665 |
0.0202 |
B2 |
97 |
32 |
40 |
0.93 |
3.41 |
0.5060 |
0.0052 |
B3 |
10 |
8 |
9 |
0.98 |
2.16 |
0.0350 |
0.0035 |
B4 |
37 |
14 |
18 |
0.91 |
2.64 |
0.1752 |
0.0047 |
B5 |
30 |
20 |
21 |
0.95 |
2.88 |
0.2467 |
0.0082 |
B6 |
56 |
25 |
30 |
0.93 |
3.15 |
0.3057 |
0.0055 |
B7 |
54 |
22 |
24 |
0.91 |
2.90 |
0.1828 |
0.0034 |
Results
of the dry and wet season surveys showed that all sampling locations had low infaunal
abundance and biomass, and low to moderate taxonomic richness. There was no observable seasonal difference
in abundance and taxonomic richness amongst the survey locations. The abundance of infaunal individuals and
taxonomic richness were higher at Site B2 in both dry and wet seasons. Pielou’s Evenness and Shannon Diversity
indices were similar across the sampling locations. Overall, the abundance and
diversity of infauna within the Study Area is similar to other areas in west of
Lamma and southern waters of Hong Kong in other studies ([2]) ([3]), and no species of conservation
importance were recorded.
During the six-month
marine mammal survey from March to August 2021, six sets of line-transect
surveys were completed to the west of Lamma Island. A total of 436.90 km of survey effort
was collected from these line-transect surveys. All the survey effort was
conducted under favourable weather conditions (i.e. Beaufort Sea State 3 or
below with good visibility) throughout the six-month study period. Furthermore, 70.1% of the total survey effort
was conducted in condition of Beaufort Sea State 2 or below, and survey data
collected in such condition can be used for encounter rate analysis of FP. The marine mammal survey data are presented
in Annex 4E.
During the six-month
marine mammal survey, only two groups of six FP were sighted along the transect
lines to the west of Lamma Island outside the Study Area, while no Chinese
White Dolphin (CWD) was sighted. The two porpoise groups were sighted
along primary lines during on-effort search, which can be utilized for
encounter rate analysis. The locations of the sightings are shown
Figure 4.5.
The two sightings of FP
were made to the south of Cheung Chau on 5 May 2021, as well as between Hei
Ling Chau and Lamma Island on 16 July 2021, respectively. One of each sighting was made in spring and
summer months with no apparent seasonal variation in their occurrence during
the six-month period. Among the two
groups of porpoises, one was a small group of two animals, while another was a
medium-sized group with four animals.
During the six-month
marine mammal survey, the encounter rates of FP was 0.65 sightings per 100 km
of survey effort. This encounter rate
was considerably lower than the combined porpoise encounter rates in southern
waters of Hong Kong as well as those recorded in Lamma survey area in the past
AFCD monitoring periods from the past decade ([4]), indicating the area within and in the vicinity
of the Study Area is not a key occurrence habitat for FP.
The key findings of the
literature review and field surveys are summarized below.
There are
no Special Areas or Conservation Areas that are relevant to marine ecology
within the Assessment Area. Recognized
sites of conservation importance include potential Marine Park at South Lamma,
Sham Wan Site of Special Scientific Interest (SSSI) and the Sham Wan Restricted
Area, locating >2.6 km away from the Key Area for potential CMP
development. The locations of these
recognized sites of conservation importance are presented in Figure 4.1. These sites are described in Annex 4A in detail.
Hermatypic hard corals
are less abundant and diverse in Hong Kong’s western waters. Ahermatypic octocorals (including gorgonians,
soft corals and black corals) which do not require light for zooxanthellae
photosynthesis, are more widely distributed in western waters and often occur
at greater depths. For Southern WCZ,
although the coral colonies were also sparse and isolated, the species
diversity were relatively higher in these waters. Hard corals, including Bernardpora stutchburyi, Porites
sp., Psammocora spp. and ahermatypic
cup coral under Family Dendrophyllidae,
octocoral, including Echinomuricea
sp., Menella sp. and Dendronephthya sp. were recorded. The ecological survey results indicated that
only isolated colonies of hard corals, cup corals, and octocorals in low
percentage cover (< 10%) were recorded in the Assessment Area.
All the benthos species
recorded in the Assessment Area from the marine ecological surveys and
literature review are common and widespread in Hong Kong without any species of
conservation importance. Amphioxus was
not recorded within and in the vicinity of the Study Area.
Only one of the two
Hong Kong’s resident marine mammal species FP has been reported to utilise the
waters in the Assessment Area, including the area within and in the vicinity of
the Study Area. FP are present in South
Lantau waters year-round and their occurrence is greater and more widespread in
these waters in the dry season (December to May). FP use a broad swathe of South Lantau waters,
particularly extending across the waters between the Soko Islands and Shek Kwu
Chau, with the proposed CMP to be located at the east of their main habitat,
where FP occurrence is recorded to be low from the literature review and the
field surveys. The area within and in
the vicinity of the Study Area is not a key habitat for FP.
The literature
suggested the presence of species of conservation importance such as Green
Turtle Chelonia mydas in the
Assessment Area. Very occasional records
of a few animals were reported previously and no opportunistic sightings of any
sea turtle occurred during the marine ecological surveys.
The major nesting site
for Green Turtle in Hong Kong is located at Sham Wan, southern Lamma Island,
which is more than 5 km from the Key Area for potential CMP development.
The
existing conditions of the marine ecological habitats and resources within the
Assessment Area have been assessed.
These baseline conditions have been based on available literature and,
where considered necessary, focussed field surveys and data review to update
and supplement the data. Based on this
information presented in Sections 4.3.2 and 4.3.3,
Annexes 4A,
4C, 4D, and 4E
the ecological importance of each habitat has been determined according to the EIAO-TM Annex 8 criteria.
Within the
Assessment Areas of this EIA, which covers quite a large areal extent,
variations in the ecological characteristics of habitats across different
locations (which are kilometres apart) are likely to be present. To provide information of key relevance to
the marine ecological assessment, the ecological importance of habitats
presented in this baseline is therefore primarily focussed on the vicinity of
the Study Area for the WL Facility.
The
ecological importance of the habitats was determined through reference to the
following:
n
Literature review;
n
Findings of the marine ecological surveys;
n
Comparison with other areas in Hong Kong; and
n
Annexes 8 and 16 of the EIAO-TM.
Outcomes of
the evaluation of ecological importance of the marine habitats and species
within the Assessment Area are presented in Tables 4.6 to 4.9.
Table 4.6 Ecological Importance of Recognised Sites of
Conservation Importance in the vicinity of the Project
Criteria |
Sham Wan SSSI and Restricted Area |
Potential South Lamma Marine Park |
Naturalness |
Natural sandy shore and marine waters |
Natural intertidal and subtidal hard and
soft bottom habitat and marine waters |
Size |
~4 ha for the SSSI; ~98 ha for the
Restricted Area |
~1,400 ha |
Diversity |
Low |
Low |
Rarity |
The sandy shore habitat is common in the
southern waters in Hong Kong. The habitat is the major nesting
site of Green Turtle in Hong Kong |
Habitats and species are common in the
southern waters in Hong Kong. Species
with conservation importance includes FP and Green Turtle |
Re-creatability |
Not re-creatable |
Not re-creatable |
Fragmentation |
Unfragmented |
Unfragmented |
Ecological Linkage |
Linked to the subtidal habitat and marine
waters off the island |
Linked to the subtidal habitats and FP
habitats nearby |
Potential Value |
Protected area for Green Turtle |
Moderate upon designation as a Marine
Park |
Nursery/Breeding Area |
Key known nesting ground for Green Turtle |
Potential nursery area for FP and Green
Turtle |
Age |
Designated as SSSI and Restricted Area in
1999; the Restricted Area was expanded in 2021 |
N/A |
Abundance |
Historically a small number of Green
Turtles were recorded to nest in Sham Wan |
Some records of FP, historically a small
number of Green Turtles were recorded |
Ecological Importance |
High |
Moderate |
Table 4.7 Ecological
Importance of Sub-tidal Hard Bottom Habitat (Coral Communities) in the vicinity of the Project
Criteria |
LPS Seawall |
Eastern coast of Cheung Chau |
Western coast of Lamma Island |
Naturalness |
Artificial, constructed habitat |
Natural |
Natural |
Size |
Large, approximately 2km in length at depth
of 2-7m |
Large, approximately 2km in length at depth of 2-7 m |
Large, approximately 2km in length at depth
of 2-8 m |
Diversity |
Low |
Low |
Low |
Rarity |
Habitats similar to the man-made habitats
in the southern and eastern waters of Hong Kong. Hard corals Duncanopsammia peltata, Porites sp.
and Oulastrea crispata, ahermatypic cup coral Tubastrea
/ Dendrophyllia sp. and Balanophyllia sp., was
recorded |
Common hard coral species were recorded,
including hard corals such as Bernardpora stutchburyi, Oulastrea
crispata, Plesiastrea versipora and Psammocora profundacella
and ahermatypic hard coral Balanophyllia sp. |
Common hard coral species were recorded,
including hard corals such as Bernardpora stutchburyi, Oulastrea
crispata, Psammocora profundacella and Porites sp., Ahermatypic hard coral Tubastrea/
Dendrophyllia sp. and Balanophyllia
sp. |
Re-creatability |
Re-creatable; substrata may be re-colonised
by subtidal organisms including corals |
Not re-creatable |
Not re-creatable |
Fragmentation |
Low.
The
surrounding coastlines comprise artificial and natural shores |
Unfragmented |
Unfragmented |
Ecological Linkage |
Not functionally linked to any high value
habitat in a significant way |
Not functionally linked to any high value
habitat in a significant way |
Not functionally linked to any high value
habitat in a significant way |
Potential Value |
Low since it is common artificial
habitat and it is unlikely to be an area of coral conservation |
Habitat is relatively undisturbed, some
potential value |
Habitat is relatively undisturbed, some
potential value |
Nursery/Breeding Area |
No significant records identified |
No significant records identified |
No significant records identified |
Age |
The artificial seawall has been in place
since the 2000s |
N/A |
N/A |
Abundance |
Very low coverage of coral is present in the
artificial seawall |
Low coverage of coral is present |
Low coverage of corals is present |
Ecological Importance |
Low |
Low |
Low |
Table 4.8 Ecological
Importance of Subtidal Soft Benthos Assemblages in the vicinity of the Project
Criteria |
Subtidal Soft Benthos Assemblages of the Study Area |
Naturalness |
Natural |
Size |
~600 ha (~235 ha for the Key Area for
potential CMP development) |
Diversity |
Low to moderate taxonomic richness of infauna |
Rarity |
Common habitat and species in Hong Kong; No
rare species or species of conservation importance recorded |
Re-creatability |
Re-creatable; substrata may be recolonised
by benthic organisms |
Fragmentation |
Unfragmented |
Ecological Linkage |
Linked to the subtidal habitats nearby |
Potential Value |
It is unlikely that the habitat could
develop conservation importance |
Nursery/Breeding Area |
No significant records identified |
Age |
N/A |
Abundance |
In comparison to other parts of the southern
waters the assemblages are of low infaunal abundance and biomass |
Ecological Importance |
Low |
Table 4.9 Ecological Importance of Marine Waters in the
vicinity of the Project
Criteria |
Marine Waters of the Study Area |
Naturalness |
Natural |
Size |
~600 ha (~235 ha for the Key Area for
potential CMP development) |
Diversity |
Scarce records of FP and no record of CWD |
Rarity |
FP is a resident species in
Hong Kong |
Re-creatability |
Not re-creatable |
Fragmentation |
Unfragmented |
Ecological Linkage |
Linked to FP and marine habitats nearby |
Potential Value |
Limited value, though near to the potential
South Lamma Marine Park |
Nursery/Breeding Area |
No significant records identified |
Age |
N/A |
Abundance |
Low density of FP in comparison to other
waters of Hong Kong. Green
Turtle might be present but transient only at very low abundance.
|
Ecological Importance |
Low |
In
accordance with EIAO-TM Annex 8 criteria, an evaluation of
species of conservation importance recorded within the Assessment Area is
presented in Table 4.10.
Table 4.10 Species
of Conservation Importance within the Assessment Area
Common Name |
Scientific Name |
Protection Status |
Distribution, Rarity and other Notes |
Literature |
Surveys |
Recorded Location |
Cup Coral |
Balanophyllia sp. |
■ Protection of
Endangered Species of Animals and Plants Ordinance (Cap.586) |
Common and widely distributed in Hong Kong,
especially in western and southern waters |
✓ |
✓ |
Along the coastline of Cheung Chau and
Lamma |
Cup Coral |
Tubastrea/ Dendrophyllia sp. |
■ Protection of
Endangered Species of Animals and Plants Ordinance (Cap.586) |
Common and widely distributed in eastern
and southern waters in Hong Kong |
✓ |
✓ |
Along the coastline of Cheung Chau and
Lamma |
Hard Coral |
Bernardpora stutchburyi Cyphastrea serailia Duncanopsammia peltata Oulastrea crispata Plesiastrea
versipora Psammocora
haimiana Psammocora profundacella Leptastrea
purpurea Porites sp. |
■ Protection of
Endangered Species of Animals and Plants Ordinance (Cap.586) |
Common and widely distributed in the
eastern waters of Hong Kong |
✓ |
✓ |
Along the coastline of Cheung Chau and Lamma |
Black Coral |
Antipathes sp. |
■ Protection of
Endangered Species of Animals and Plants Ordinance (Cap.586) |
Common and widely distributed in Hong Kong,
especially in the north-eastern waters of Hong Kong |
✓ |
✓ |
Along the coastline of Lamma |
Green Turtle |
Chelonia mydas |
■ Wild Animals
Protection Ordinance (Cap.170) ■ Protection of
Endangered Species of Animals and Plants Ordinance (Cap.586) ■ Listed as
“Critically Endangered” in the China Species Red List ■ Listed as “Grade
II National Key Protected Species” in China ■ Listed as "
Endangered" in the IUCN Red List of Threatened Species |
Known to nest mainly at Sham Wan, south of
Lamma Island. Nesting was also recorded in Shek Pai Wan and Tung O
on Lamma Island, Tai Wan in Sai Kung, Tai Long Wan in Shek O, and a beach on
Lantau Island. Inter-nesting areas largely located to the south and
southeast of Lamma Island |
✓ |
|
Not specific, in southern waters of Hong
Kong |
Finless Porpoise |
Neophocaena phocaenoides |
■ Wild Animals
Protection Ordinance (Cap.170) ■ Protection of
Endangered Species of Animals and Plants Ordinance (Cap.586) ■ Listed as
“Endangered” in the China Species Red List ■ Listed as “Grade
II National Key Protected Species” in China ■ Listed as
"Vulnerable" in the IUCN Red List of Threatened Species |
Range across Hong Kong southern and eastern
waters from Soko Islands to Tung Ping Chau, and in PRC waters |
✓ |
✓ |
In the vicinity of the Study Area |
Based on
the review of available information within the Assessment Area, marine
ecological sensitive receivers that may be affected by the Project activities
have been identified in accordance with the EIAO-TM criteria, and are
consistent with the ones identified in the water quality impact assessment (Section 3). These sensitive
receivers and their distance from the Project are listed in Table
4.11 and presented in Figure 3.3.
Table 4.11 Approximate Shortest Distance to Marine Ecological
Sensitive Receivers in the vicinity of the Project
Description |
Location |
Shortest
Geodesic Distance from Key Area (km) |
Marine Park |
Potential South Lamma Marine Park |
2.6 |
Corals |
Cheung Chau |
3.2 |
Hei Ling Chau |
3.7 |
|
Chi Ma Wan Peninsula |
6.4 |
|
Sunshine Island |
4.7 |
|
Kau Yi Chau |
6.8 |
|
Siu Kau Yi Chau |
7.8 |
|
Hung Shing Yeh |
3.7 |
|
Ha Mei Wan |
3.5 |
|
Pak Kok |
4.3 |
|
Shek Kok Tsui |
3.0 |
|
Sandy Bay |
7.0 |
|
Green Island |
7.9 |
|
Peng Chau |
7.3 |
|
Sham Wan |
5.4 |
|
Green Turtle Nesting Ground |
Sham Wan |
5.4 |
A desktop literature
review and supporting field surveys were conducted in order to establish the
ecological profile of the area within and surrounding the Project. The importance of potentially-impacted
ecological resources identified within the Assessment Area was evaluated using
the methodology defined in the EIAO-TM. Potential impacts to these resources due to
the construction and operation activities of the Project were assessed
(following the EIAO-TM Annex 16 guidelines) and the impacts
evaluated (based on the criteria in EIAO-TM
Annex 8). Findings of water quality modelling (Section
3) are used, where appropriate, to assess potential impacts on the
identified marine ecological resources.
The key
construction and operation activities of the Project are discussed in Section
2.6.4. Potential sources of
impacts to marine ecology arising from the Project may occur during both
construction and operation activities, including:
Construction
activities:
§ Dredging of the seabed for the formation of CMP
Operation
activities:
§ Disposal of contaminated sediment in the formed CMP
§ Capping of the exhausted CMP by uncontaminated sediment up to the original seabed level
Note that the construction activities
(dredging) could overlap with operation activities (backfilling and capping) to
maintain uninterrupted disposal service of the proposed WL Facility. The potential ecological impacts associated with the construction and
operation activities of the Project are assessed as a whole and presented in
separate sections for marine ecological resources (excluding FP) (Section 4.5) and FP (Section 4.6).
Potential impacts to marine ecological resources (excluding FP) that
may arise from the construction and operation activities are summarized
in Table 4.12 and
discussed further in the following sections. It should be noted that the proposed CMPs are located >2 km away from the
nearby intertidal habitats at Lamma Island and disturbance to these habitats is
not expected to occur. Unacceptable impacts on these habitats are
not expected and thus these intertidal habitats will not be discussed further
in this EIA study.
Table 4.12 Potential Impacts to Marine Ecological Resources
(Excluding FP)
Nature
of Impact |
Habitat
Affected |
Potential
Impact |
Temporary habitat loss and disturbance |
Subtidal habitats and marine waters within
and in the vicinity of the CMPs |
Temporary loss of ~100ha
seabed within Key Area during construction and operation activities of the
CMPs at any one time; Temporary loss of a total
of ~190ha seabed for all the seven proposed CMPs within the Key Area |
Underwater sound from construction and
operation activities |
Marine waters within and in the
vicinity of the CMPs |
Vibration and disturbance to
nearby organisms |
Changes in water quality from
construction and operation activities |
Marine waters and subtidal habitats
within
and in the vicinity of the CMPs |
Potential water quality impacts
and deposition of sediment onto the seabed affecting organisms |
Increased marine traffic from
construction and operation activities |
Marine waters within and in the
vicinity of the CMPs |
Potential for injury of Green
Turtles from vessel strike |
Effects of glare from light
sources of construction and operation activities |
Marine waters within and in the
vicinity of the CMPs |
Potential for disturbance
impacts resulting in behavioral changes of Green Turtles |
Accidental spillage/leakage of
fuels/ chemicals |
Marine waters and subtidal
habitats within and in the vicinity of the CMPs |
Potential water quality impacts
on organisms |
Direct impacts to subtidal
bottom assemblages will occur as a result of the dredging, backfilling and
capping works of the CMPs. However, once
capping works of CMP are completed, the seabed and hydrodynamic regime at the
CMP will be reinstated to the original condition. Benthic communities are expected to
recolonize the seabed at CMP after the capping works.
Findings from the
literature review, supplemented by the field surveys, indicate that the benthic
assemblages within the Study Area were dominated by polychaetes and
characterised by low to moderate species richness and low abundance and biomass
of species found elsewhere in Hong Kong. The seabed of the Study
Area is covered by marine sediment comprised primarily of silt / clay and hard
corals were not recorded within the Study Area.
All of the species recorded occur frequently in Hong Kong and
no rare species or species of conservation importance were
recorded. As a result, the assemblages were considered as of low
ecological importance (Table 4.8).
As the CMPs will be
constructed and operated sequentially depending on the disposal demand, it is
expected that ~100ha of seabed habitats within the Key Area will be temporarily
lost or disturbed due to the construction and operation activities of the
proposed CMPs at any one time throughout the service lifetime of the WL
Facility. The areas of affected habitats
are expected to be similar to surrounding seabed areas. As such, the
potentially directly impacted subtidal habitats within the Key Area are
well-represented in the region and losses will represent a very small fraction
of widely available habitat. Given the low ecological value of the
associated benthic assemblages, and the recolonization of similar organisms
following completion of capping works of the CMP, unacceptable impacts on the
benthic communities are not expected.
Furthermore, although
Green Turtles have been reported in the habitats near the Project, their
occurrence is highly opportunistic. It
is unlikely that these habitats represent unique habitats that the species
would rely on. The Green Turtle nesting
ground at Sham Wan and the Potential South Lamma Marine Park are located > 5
km and > 2.5 km away, respectively, from the Key Area and unacceptable impacts
on Green Turtles and the potential South Lamma Marine Park are not expected.
Intermittent sounds,
which occur during construction and operation activities such as dredging
works, backfilling and capping works and marine vessel movement, may have an
impact on marine ecological resources. Potential effects of
increased underwater sound include physiological stress, avoidance and injury
(at high pressure levels). The level of impact is however dependent
upon background sound, number and type of species affected, proximity of organism
to the sound source, attenuation properties of seabed sediments and hearing
capabilities of the species affected, etc..
Most marine
invertebrates do not possess air-filled space and thus it is generally
considered that sound would have limited physiological or behavioural effects
on marine invertebrates, except if they are located within a few metres of the
sound source. In addition, waters within the Assessment Area and its
vicinity is subject to relatively high levels of marine traffic by similar types
of vessels; therefore it is reasonable to assume that marine invertebrates and
Green Turtles in these waters are habituated to a relatively high background
level of underwater sound, and a small increase in vessel activity associated
with the construction and operation of this Project is not anticipated to
result in unacceptable impacts on these marine ecological resources.
Dredging, backfilling
and capping activities are expected to generate suspended solids (SS) and may result in
increased sediment deposition on the seabed in close proximity to the works
areas. Computational modelling has been
undertaken to analyse suspended sediment dispersion from such works (Section
3.7).
Impacts to benthic
communities immediately outside of the works areas are expected to occur
temporarily as the modelling results indicate that dredging, backfilling and
capping activities would only result in localised elevations of SS. Benthic communities in the vicinity of the
CMPs are considered to be of low ecological value (Table 4.8). As the areas affected are often exposed to SS
laden discharges from the Pearl River, the organisms present are thus assumed
to be adapted to SS elevation. Based on
the assumption that eventually the affected areas will be recolonised by
benthos typical of the area, then the temporary loss of these low ecological
value benthic assemblages is not considered to be unacceptable.
Coral communities are
located >3 km away from the Key Area where CMPs of the Project are
situated. The elevations in SS and
sedimentation rate are not predicted to affect coral colonies in the vicinity
of the CMPs at levels of concern (as defined by the WQO and tolerance criterion
and assessed in Section 3.7). Based on
literature and the field surveys, the coral communities within the Assessment
Area were generally recorded to be of low coverage (< 10%) and of low
ecological value (Table 4.7). The coral
species recorded in the Assessment Area are generally adapted to the turbid
conditions in southern waters. As such,
unacceptable impacts to the coral colonies due to elevation in SS and
sedimentation rate are not anticipated.
Similarly, water quality modelling results (Section 3.7) indicated
that there will be minor elevation of SS at the potential South Lamma Marine
Park and Green Turtle nesting ground at Sham Wan and such SS elevation complied
with the WQO criterion.
With the proposed
mitigation measures of implementation of cage-type silt curtain during dredging
works by grab dredgers and controlled work rates for dredging, backfilling and
capping works, unacceptable residual impacts are not anticipated. Consequently, unacceptable impacts on marine
ecological resources, including coral and benthic communities, Green Turtles
and the potential South Lamma Marine Park, are not expected.
The relationships
between SS and DO are complex, with increased SS in the water column combining
with a number of other factors to reduce DO concentrations in the water
column. Elevated SS (and turbidity)
reduces light penetration, lowers the rate of photosynthesis by phytoplankton
(primary productivity) and thus lowers the rate of oxygen production in the water
column, also release organic matter and thus lead to DO depletion. This has a particularly adverse effect on the
eggs and larvae of fish, as at these stages of development, high levels of
oxygen in the water are required for growth due to their high metabolic
rate. DO depletions are most likely to
affect sessile organisms as they cannot move away from areas where DO is low
(unlike mobile species such as fish).
With reference to the
water quality modelling results (Section 3.7), dredging, backfilling
and capping of CMPs would only generate temporary and localised low level SS
elevation and not significant depletions of DO.
Depletions of DO as a result of the construction and operation
activities of the Project have been predicted to be undetectable and compliant
with the relevant WQOs. It is thus
expected that no unacceptable impacts to the marine ecological resources,
including coral and benthic communities, Green Turtles and the potential South
Lamma Marine Park, present in the vicinity of the CMPs will occur.
High levels of
nutrients (TIN and UIA) released from disturbed sediments to seawater may
potentially cause rapid increases in phytoplankton to the point where an algal
bloom may occur. An intense bloom of
algae can lead to sharp increases in DO levels in surface water. However, at night and when these algae die
there is usually a sharp decrease in the levels of dissolved oxygen in the
water, as dead algae fall through the water column and decompose on the
bottom. Anoxic conditions may result if
DO concentrations are already low or are not replenished. This may result in mortality to marine
organisms due to oxygen deprivation.
The water quality
modelling results (Section 3.7) have indicated that dredging, backfilling and
capping of CMPs would generate low level TIN and UIA elevation in a localised
area close to the works. Consequently
TIN and UIA levels are not expected to increase from background conditions
during the construction and operation activities of the Project. Algal blooms and unacceptable impacts to the
marine ecological assemblages and habitats present in the vicinity of the
marine works areas are not expected to arise due to the works.
Heavy metals, metalloid
and trace organic compounds from the sediment samples analysed under this EIA
indicated that the levels of these contaminants are below the corresponding
proposed assessment criteria (Section 3.7). Dredging works of CMPs would unlikely result
in significant release of sediment-bounded pollutants into the water
column. Similarly, as uncontaminated
sediments will be used for capping works of CMPs, it is unlikely to result in
significant release of sediment-bounded pollutants into the water column. The water quality modelling results (Section
3.7) have indicated that backfilling of contaminated sediments would
not result in unacceptable water quality impacts. Therefore, no unacceptable adverse impact to
the marine ecological assemblage and habitats with the release of
sediment-bounded pollutants from dredging, backfilling and capping works would
be expected.
Dredging, backfilling and capping works of the CMPs will require the use of works vessels such as dredgers, tug boats, hopper barges, etc.. There are two main ways of increased vessel movements due to the construction and operation activities that may potentially impact Green Turtles. Firstly, vessel movements may potentially increase physical risks to Green Turtles. Secondly, the physical presence of works vessels may cause short-term avoidance of the area where works vessels are operating, and this has been discussed in Section 4.5.1 in terms of temporary disturbance.
It has been reported that sea turtles have been killed or injured by vessel collisions and the risk is mainly associated with high-speed vessels such as high-speed ferries ([5]). In terms of potential impacts arising from works vessel movements of this Project, the risk of vessel collision is considered to be very small, as works vessels would be slow-moving. Works vessels would typically travel at up to about 10-12 knots during transit. Slow-moving vessels would not pose a significant risk to Green Turtles.
The Project is expected to involve a relatively small number of works vessels (e.g. up to 2 dredgers, some tugs/ supporting vessels, some hopper barges for sediment handling at any one time), and the frequency/ trip of works vessels would also be relatively low in general (expected to be no more than 84 trips per day at the peak work rates) when comparing to the traffic densities at the nearby fairways (e.g. Adamasta Channel TSS and East Lamma Channel TSS with a range of a daily average of 368-432 numbers of marine traffic volume in December 2019 based on Automatic Identification System and radar data). Works vessels would make use of designated fairways and route to access the CMP area. It should be noted that waters off southern Hong Kong have high levels of existing marine traffic. In this context, vessel traffic associated with the proposed Project would represent only a minor incremental increase in marine traffic in the area.
Given the slow-moving nature of the relatively small number of works vessels involved in the construction and operation activities of the Project, unacceptable adverse impacts of increased marine traffic on Green Turtles are not anticipated.
Cage-type silt curtain are proposed to be deployed for dredging works by grab dredgers. The extent of the silt curtain deployment would be managed and controlled to minimize disturbance to Green Turtles in the area. Similar arrangements for silt curtain deployment have been adopted for marine projects in Hong Kong and no incidents of injury or entanglement of sea turtles have been reported. Therefore unacceptable adverse impacts on Green Turtles are not anticipated.
The CMPs will be constructed and operated during both daytime and night-time. The works vessels for the dredging, backfilling and capping works of the CMPs will require operational and navigational lightings to meet operational need and in line with the maritime requirements. The lighting is expected to be similar to the nearby marine traffic travelling around the Project area through the nearby fairways.
Of the marine ecological
resources, potential impacts to Green Turtles from glare effect of light
sources are relevant and assessed.
Marine turtle behaviour at nesting beaches is largely guided by light
cues and they have a tendency to orientate towards brightness ([6]). As a result, lighting from coastal
developments has a potential to disrupt the behaviour of nesting adult turtles
and hatchlings ([7]). Hatchlings use light as a cue to locate the
ocean and are often attracted or disorientated by artificial light rather than
being deterred by it, which can lead to mortality through exhaustion,
dehydration or predation. Adults have
been observed to continue nesting despite the introduction of artificial light
on beaches and sea-finding behaviour by adults is rarely disrupted by
artificial lighting ([8]).
Given the Project is located > 5 km away from the Green Turtle nesting ground at Sham Wan and shielded by the landmass at southwest of Lamma Island, there is no potential for glare effect of light sources to interfere with the behaviour of any turtle hatchlings or affect normal adult nesting behaviour. Unacceptable adverse impacts from glare effect of light sources on Green Turtles are not anticipated.
The use of
fuel/chemicals associated with the works vessels and construction plants would
mean there is a potential of spillage or leakage of such materials if not
properly managed. It is expected that
chemicals used on the works vessels would be held in low quantities. Fuel spill or leaks would tend to float on
the water surface and will evaporate into the atmosphere and dissipate
rapidly. The potential for impact to
specific biota would depend on the nature and degree of exposure received by a
particular individual. However, given
the risk of spillage and leakage would generally be limited to minor volumes,
no significant impacts would be expected in the event that an unplanned
accidental spill or leak occurred.
Measures would be implemented for the safe storage, handling and
disposal of chemicals and oils to prevent the release into the marine
environment. Precautionary measures such
as bunding of machinery areas and availability of spill clean-up kits would be
in place to prevent spillage or leakage of fuel/chemical to reach the marine
environment. Unacceptable impacts on
marine ecological resources, including coral and benthic communities, Green
Turtles and the potential South Lamma Marine Park, are thus not expected.
As FP is the only resident marine mammal species utilising the water
within the Assessment Area, the impact assessment for this EIA Study focusses
on FP. Potential impacts to FP that may
arise from the construction and operation activities are summarized in Table 4.13 and discussed further
in the following sections.
Table 4.13 Potential Impacts to Finless Porpoises
Nature
of Impact |
Habitat
Affected |
Potential
Impact |
Temporary habitat loss and disturbance |
Marine waters within and in the vicinity of
the CMPs |
Disturbance to habitats
within the areas of active CMPs |
Underwater sound from construction and operation
activities |
Marine waters within and in the
vicinity of the CMPs |
Potential for acoustic
disturbance resulting in behavioural changes and hearing injury |
Increased marine traffic from construction
and operation activities |
Marine waters within and in the
vicinity of the CMPs |
Potential for injury from
vessel strike |
Changes in water quality from
construction and operation activities |
Marine waters within and in the
vicinity of the CMPs |
Potential indirect impacts due
to changes in water quality |
Potential for secondary impacts
due to changes in prey resource distribution |
||
Potential for secondary impacts
from contaminant release from seabed disturbance leading to potential
bioaccumulation effects |
||
Accidental spillage/leakage of
fuels/ chemicals |
Marine waters within and in the
vicinity of the CMPs |
Potential for sublethal
toxicity effects and irritation |
The construction and
operation of the proposed CMPs will result in a temporary habitat loss and
disturbance of seabed within the Key Area.
The CMPs will be constructed and operated sequentially depending on the
disposal demand and it is expected that ~100ha of seabed habitats within the
Key Area will be temporarily lost or disturbed due to the construction and
operation activities of the proposed CMPs at any one time throughout the
service lifetime of the WL Facility.
From the literature
review and the field surveys, while FP utilise the waters in the Assessment
Area, including the area within and in the vicinity of the Study Area, FP
occurrence was recorded to be consistently low over the past years and the area
within and in the vicinity of the Study Area is not a key habitat for FP. Therefore, the marine waters of the Study
Area is considered of low ecological importance (Table 4.9).
The construction and
operation activities of the Project will involve dredging, backfilling and
capping works. These activities will use
a small number of works vessels at the Key Area (e.g. up to 2 dredgers, some tugs/
supporting vessels, some hopper barges for sediment handling at any one
time). Considering the temporary nature
of the disturbance and with controlled work rates for dredging, backfilling and
capping works, impacts on FP are expected to be of minor significance. Upon cessation of the disturbance, no
significant change in marine mammal distribution, abundance and usage pattern
in the wider Hong Kong waters is expected.
Dredging, backfilling
and capping works of the CMPs are expected to result in a minor increase in
underwater sound from the dredging works (e.g. sediment removal using grab or
draghead of TSHD), transit of works vessels (e.g. sound from engine/ propeller)
and sediment discharge onto seabed of CMPs (e.g. bottom dumping or pump-out
from TSHD).
Small cetaceans are acoustically sensitive at certain frequencies, and sound is important to their behavioural activities. Sound that masks communications for socializing and group cohesion or echolocation for foraging could have a potential impact. The reactions from impacted cetaceans can range from brief interruption of normal activities to short- or long-term displacement from noisy areas. Although pulsed high-energy sound also has the potential to induce physical hearing injury in marine mammals, this is unlikely other than in the immediate vicinity of the noisy activities. Most small cetaceans can hear with the range of 1 to 150 kHz, though the peak for a variety of species is between 8 kHz and 90 kHz and between 20 kHz and 145 kHz reported for dolphins and porpoises respectively ([9])([10]). FP produce high frequency ultrasonic narrowband clicks at a peak frequency of 142 kHz, which are inaudible to the human ear ([11]).
Dredging works and large vessel traffic (e.g. tugs and barges) generally results in low frequency noise, typically in the range of 0.02 to 1 kHz ([12])([13]), which is below the good hearing range between 20 kHz and 145 kHz reported for porpoises. A local study was conducted to investigate the underwater sound levels produced during the installation of submarine cable in southeastern waters of Hong Kong ([14]). The results indicated that the cable installation barge and other large vessel traffic (e.g. tugs and barges) (with total up to 4 nos. vessels) generated sound with frequency between 40 Hz and 25 kHz and the underwater sound generated was concentrated between 50 Hz and 400 Hz, which were lower than the sound used for foraging and communication for FPs.
Regarding the noise generated from dredging works which are the key underwater noise source of the Project, the source level of dredging activity can be affected by various factors including type of dredging vessels, sediment type for dredging, water depth, salinity and temperature ([15])([16]). It was reported that different types of dredgers can emit sound at a source level of ~160-180 dB re 1 µPa2m2 ([17]). By applying underwater noise propagation modelling by the geometrical spreading laws for sound intensity, it is expected that the underwater sound levels could be lowered to <153 dB re 1μPa within a localised area of ~63 m from the sound source ([18]) which is below the temporary threshold shift (TTS) for porpoises (i.e. very high-frequency cetaceans) ([19]).
For these reasons, noise generated by dredging works and large vessel traffic (e.g. tugs and barges) is not expected to acoustically interfere significantly with FP. FP may have short-term avoidance of the immediate works areas of sound generating activities, but are expected to return when the disturbance ceases. Unacceptable adverse impacts of increased underwater sound level on FP are not anticipated.
Overall, the sound produced during the dredging, backfilling and capping works of the CMPs would be audible and may overlap and mask frequencies of FP including those used for socializing, but would not likely mask the ultrasonic frequencies used in echolocation for foraging. The waters in the vicinity of the proposed CMPs is a potential habitat for FP, though is not a key occurrence habitat and hence of low ecological importance. FP would be expected to respond by avoiding a localised works area near the CMPs and the effect would be limited to behavioural disturbance impacts on affected individuals only without affecting the functionality of key habitats such as the waters between the Soko Islands and Shek Kwu Chau. In the context of the size of the range of these animals, the size of the disturbed area would be small, and no significant long-term change in marine mammal distribution, abundance and usage pattern in the wider Hong Kong waters is expected. Unacceptable adverse impacts of increased underwater sound level on FP are not anticipated.
As discussed in Section 4.5.4, works vessels such as dredgers, tug boats, hopper barges, etc. will be used for the construction and operation activities of the Project. There are two main ways of increased vessel movements due to the construction and operation activities that may potentially impact FP. Firstly, vessel movements may potentially increase physical risks to FP. Secondly, the physical presence of works vessels may cause short-term avoidance of the area where works vessels are operating, and this has been discussed in Section 4.6.1 in terms of temporary disturbance.
In Hong Kong, there have been instances when marine mammals have been killed or injured by vessel collisions ([20])([21])([22]), but it is thought that this risk is mainly associated with high-speed vessels such as high-speed ferries. As discussed in Section 4.5.4, a relatively small number of slow-moving works vessels (e.g. up to 2 dredgers, some tugs/ supporting vessels, some hopper barges for sediment handling at any one time), and the frequency/ trip of works vessels would also be relatively low in general (expected to be no more than 84 trips per day at the peak work rates) when comparing to the traffic densities at the nearby fairways (e.g. Adamasta Channel TSS and East Lamma Channel TSS with a range of a daily average of 368-432 numbers of marine traffic volume in December 2019 based on Automatic Identification System and radar data). The waters off southern Hong Kong have high levels of existing marine traffic and the vessel traffic associated with the proposed Project would represent only a minor incremental increase in marine traffic in the area. Works vessels would make use of designated fairways and route to access the CMP area. Given the slow-moving nature of the relatively small number of works vessels involved in the Project, unacceptable adverse impacts of increased marine traffic on FP are not anticipated.
Cage-type silt curtain are proposed to be deployed for dredging works by grab dredgers. The extent of the silt curtain deployment would be managed and controlled to minimize disturbance to FP in the area. Similar arrangements for silt curtain deployment have been adopted for marine projects in Hong Kong and no incidents of injury or entanglement of marine mammals have been reported. Therefore unacceptable adverse impacts on FP are not anticipated.
Elevation of SS and depletion of DO do not appear to have a direct impact on FP since these animals are air breathing and therefore SS in the water column as a result of dredging, backfilling and capping works have no effect on their respiratory surfaces. Also marine mammals, including FP, have evolved to inhabit areas near river mouths and estuarine-influenced coastal waters and are therefore well-adapted for hunting in turbid waters, owing to their use of echolocation, in addition to visual information.
With reference to the water quality modelling results (Section 3.7), fisheries resources are not predicted to be adversely affected, as the SS and nutrient elevations and DO depletion are localised to the areas of active CMPs (and sites of dredged sediment disposal). It should be noted that marine mammals and their prey species are naturally exposed to high levels of SS in the Pearl River Estuary. Therefore, impacts to FP through loss of localised feeding habitat (fisheries resources) are not predicted to occur. It is thus expected that adverse impacts to FP arising from potential change in water quality will not occur.
Another potential impact on FP associated with the construction and operation activities of the Project is the potential bioaccumulation of released contaminants from contaminated sediments. The potential for release of contaminants from disturbed sediments has been assessed in Section 3.7. Sediment samples collected within the Study Area indicated low levels of sediment contamination within the Project Site. Therefore, risk of release of sediment-bounded contaminant from dredging works of the Project is minimal and impact to fisheries resources and thus to FP due to potential contaminant release is not expected. The water quality modelling results (Section 3.7) have indicated that the levels of the contaminants released during backfilling are below the corresponding proposed assessment criteria and backfilling of contaminated sediments would not result in unacceptable water quality impacts. An assessment on bioaccumulation was also conducted for this study and the results showed that the increase in contaminants’ concentration of fisheries resources is insignificant (see Section 8). In addition, with reference to the long-term environmental monitoring data from ESC CMPs, the concentrations of contaminants for tissues/ whole body samples of fisheries resources (including pelagic fish, molluscs, predatory crabs, predatory fish and predatory shrimps) collected between reference area (i.e. away from CMPs) and impact area (i.e. closer to the CMPs) were found to be similar over the years ([23]), indicating there is no evidence of adverse impact to bioaccumulation of prey resources collected near the CMP area due to the potential release of sediment-bounded contaminant. Impacts on FP due to bioaccumulation of released contaminants from dredging, backfilling and capping works are not expected to occur.
As discussed in Section 4.5.4, the risk of spills and leaks would generally be limited to minor volumes and with implementation of preventative measures including bunding areas and provision of spill kit, no significant impacts to FP would be expected.
From the information presented in Sections 4.5 and 4.6, the significance of the ecological impacts associated with the construction and operation activities of the proposed Project has been evaluated in accordance with the EIAO-TM (Annex 8, Table 1). The outcomes of this evaluation are summarised in Table 4.14.
Table 4.14 Significance of
Ecological Impacts Associated with the Construction and Operation Activities of
the Proposed Project Evaluated in accordance with EIAO-TM
Potential Impact |
Ecological Sensitive Receiver |
Nature of Impact |
Overall Impact Significance |
Mitigation / Precautionary Measures Required |
|||||
Habitat Quality |
Species Affected |
Size |
Duration |
Reversibility |
Magnitude |
||||
Marine Ecological Resources
(excluding Finless Porpoises) |
|||||||||
Temporary habitat
loss and disturbance |
Coral and benthic communities, Green
Turtles |
Low |
Common and widespread coral
species; Common benthic fauna dominated
by polychaete bristleworms |
A total of ~190ha of seabed within Key Area |
Temporary |
Reversible |
Small |
Minor |
No |
Underwater sound
from construction and operation activities |
Marine invertebrates, Green Turtles,
potential South Lamma Marine Park |
Low to moderate |
Common and widespread species |
In the vicinity of active CMP areas and
vessel transit routes |
Temporary |
Reversible |
Small |
Minor |
No; precautionary measures would further
reduce impacts |
Changes in water quality from
construction and operation activities |
Coral and benthic communities, Green
Turtles, potential South Lamma Marine Park |
Low to moderate |
Common and widespread species |
The area affected is expected to be within
a short distance of the active CMP areas |
Temporary |
Reversible |
Small |
Minor |
No; water quality mitigation measures would
further reduce impacts |
Increased marine traffic from
construction and operation activities |
Green Turtles |
Low |
Green Turtle |
In the vicinity of active CMP areas and
vessel transit routes |
Temporary |
Reversible |
Small |
Minor |
No; precautionary measures would further
reduce impacts |
Effects of glare from light
sources of construction and operation activities |
Green Turtles |
Low |
Green Turtle |
In the vicinity of active CMP areas and
vessel transit routes |
Temporary |
Reversible |
Small |
Minor |
No |
Accidental spillage/leakage of
fuels/ chemicals |
Coral and benthic communities, Green
Turtles, potential South Lamma Marine Park |
Low to moderate |
Common and widespread species |
Area affected in the vicinity of
the spill/leak, scale dependent on spill volume and trajectory |
Temporary |
Reversible |
Very small |
Negligible |
No; precautionary measures would further
reduce impacts |
Finless Porpoises (FP) |
|||||||||
Temporary habitat
loss and disturbance |
FP |
Low |
FP |
Confined to localised active
CMP areas |
Temporary |
Reversible |
Small |
Minor |
No |
Underwater sound
from construction and operation activities |
FP |
Low |
FP |
Confined to localised active
CMP areas |
Temporary |
Reversible |
Small |
Minor |
No; precautionary measures would further
reduce impacts |
Increased marine
traffic from construction and operation activities |
FP |
Low |
FP |
In the vicinity of active CMP areas and
vessel transit routes |
Temporary |
Reversible |
Small |
Minor |
No; precautionary measures would further
reduce impacts |
Changes in water quality from
construction and operation activities |
FP |
Low |
FP |
The area affected is expected to be within
a short distance of the active CMP areas |
Temporary |
Reversible |
Small |
Minor |
No; water quality mitigation measures would
further reduce impacts |
Accidental spillage/leakage of
fuels/ chemicals |
FP |
Low |
FP |
Area affected in the vicinity
of the spill/leak, scale dependent on spill volume and trajectory |
Temporary |
Reversible |
Very small |
Negligible |
No; precautionary measures would further
reduce impacts |
Information from
publicly available sources suggested that the construction/ implementation
programmes of a number of projects would coincide with this Project (see Annex 2A for
concurrent projects identified). The
water quality impact assessment (Section 3) was based on the
worst-case scenarios of concurrent construction and operation activities of
this Project as well as relevant concurrent projects (see Annex 3A for the
detailed consideration) and thus has also incorporated potential cumulative
impacts. The cumulative impacts of the
various construction and operation activities of this Project and other
relevant concurrent projects have been demonstrated in Section 3.9
as not causing unacceptable impacts to water quality. Consequently, unacceptable cumulative impacts
to marine ecological resources are not predicted to occur.
Coral and benthic
communities to be impacted by the Project are considered as of low ecological
value and impacts were assessed to be minor.
Effects on these habitats and assemblages as a result of this Project
are not anticipated to contribute to unacceptable cumulative impacts with other
developments in the Assessment Area and the wider Hong Kong waters. As for the potential cumulative impacts on
FP, impacts presented in Section 4.6 were examined to
evaluate potential cumulative impacts with other developments in the Assessment
Area, including the South of Cheung Chau Open Sea Sediment Disposal Area,
Improvement Dredging for Lamma Power Station Navigation Channel, Development of
an Offshore Wind Farm in Hong Kong and the Artificial Islands in the Central
Waters located within a few kilometres from the Project. Outcomes of this evaluation are summarised as
follows:
n
Habitat Loss
and Disturbance: the extent of
disturbance of the Project is expected to be small, temporary and confined to
localised active CMPs at the Key Area (~100 ha habitat loss at any one time for
dredging, backfilling and capping activities).
The South of Cheung Chau Open Sea Sediment Disposal Area is expected to
result in a temporary disturbance of a maximum of 600 ha seabed habitat at any
one time, though the seabed disturbance is expected to be confined in
particular areas where disposal activities would occur. The Improvement Dredging for Lamma Power
Station Navigation Channel is expected to result in a temporary disturbance of
262 ha seabed habitat. The Development
of an Offshore Wind Farm in Hong Kong is expected to result in a loss of 0.16
ha seabed habitat. The severity of such
cumulative habitat loss is expected to be significantly reduced to acceptable
levels by mitigation measures proposed as part of the EIAs for the Improvement
Dredging for Lamma Power Station Navigation Channel and Development of an
Offshore Wind Farm in Hong Kong. Most of
the habitat loss and disturbance from these projects are temporary and the
habitats will recover once the projects are completed. Benthic
communities are expected to recolonize the seabed, which will become habitats
for fisheries resources and then provide feeding habitat (fisheries resources)
for FP. Considering the temporary nature and relatively small size (~100 ha
habitat loss at any one time for dredging, backfilling and capping activities)
of the Project, it is not expected to
exert an unacceptable cumulative effect. On the other hand, the
development of the Artificial Islands in the Central Waters are expected to
result in a permanent loss of ~1,000 ha seabed.
The KYCAI development is currently in early planning stage and effective
and feasible mitigation measures, including compensation measures, will be
investigated under the CW Study to address the permanent loss of seabed due to
the proposed development ([24]). The
acceptability of residual cumulative impacts on marine ecology from the said
concurrent projects will largely depend on the environmental acceptability of
the reclamation of KYCAI and the HKI-NEL Link in the Central Waters.
n
Underwater Sound: the Project is located at sufficient distance
from other projects and only a relatively small number of slow-moving works
vessels would be used for the Project.
Given the similarity in underwater acoustic profiles generated by works
vessels of this Project and other projects (e.g. by the use of large vessels
generating low-frequency sound), cumulative effects of works vessels
operational sound, if any, are anticipated to be negligible.
n
Marine Traffic: the Project is located at sufficient distance
from other projects in the vicinity. It
is expected to involve a relatively small number of works vessels (e.g. up to 2 dredgers, some tugs/ supporting
vessels, some hopper barges for sediment handling at any one time), and the frequency/
trip of works vessels would also be relatively low in general (expected to be
no more than 84 trips per day at the peak work rates) when comparing to the
traffic densities at the nearby fairways (e.g. Adamasta Channel TSS and East
Lamma Channel TSS with a range of a daily average of 368-432 numbers of marine
traffic volume in December 2019 based on Automatic Identification System and
radar data). Given the waters off southern Hong Kong have
high levels of existing marine traffic, the cumulative effects of marine
traffic disturbance and marine mammal collision risk, if any, are anticipated
to be minor. It is expected that
similar, slow-moving works vessels would be used in this Project and other
projects, and similar mitigation measures, e.g. regular routes (Section
4.9) would be adopted in different projects to minimise the magnitude
of potential cumulative impacts.
Other projects
either do not have a marine element or are at more than a few kilometres from
this Project, and so no unacceptable cumulative impact on marine ecological
resources, including FPs, is expected.
On the basis of the above, no unacceptable cumulative impact on marine
ecological resources, including FPs, is expected.
In accordance with
the guidelines in the EIAO-TM on marine ecological impact assessment,
the approach adopted in this EIA for mitigating impacts to marine ecology, in
order of priority, includes:
n
Avoidance:
Potential impacts should be avoided to the maximum extent practicable by
adopting suitable alternatives;
n
Minimisation: Unavoidable impacts should be minimised by taking appropriate and
practicable measures such as confining works in specific area or season; and
n
Compensation: The loss of important species and habitats may
be provided for elsewhere as compensation.
Enhancement and other conservation measures should always be considered
whenever possible.
Impacts to marine
ecological resources have largely been avoided (i.e. avoid direct and indirect
impacts to ecologically sensitive habitats as far as practicable through site
selection; see Section 2.5) and reduced through proper planning and design of
the CMPs (e.g. CMPs to be developed within Key Area, CMPs
to be constructed and operated sequentially and no more than three
pits will be active (dredging / backfilling / capping) at any one time). The
construction and operation activities have been designed (e.g. appropriate work
rates for dredging, backfilling and capping) to confirm compliance with the
assessment criteria at sensitive receivers and control water quality impacts to
within acceptable levels and water quality mitigation measures (e.g. deployment
of cage-type silt curtain during dredging works, good site practices) will be
implemented to further avoid/reduce potential impacts (see Section 3). These measures are expected to control and
reduce potential impacts to marine ecological resources as well. Other precautionary measures for marine
ecological resources are also recommended in the following sections.
The following
precautionary measures to reduce potential impacts from the construction and
operation activities of the Project on the marine ecological resources,
including Green Turtles and FP, are recommended:
n
Vessel
operators will be required to control and manage all effluent from
vessels. These kinds of wastewater shall
be brought back to port where possible and discharged at appropriate collection
and treatment system to prevent avoidable water quality impacts;
n
A policy
of no dumping of rubbish, food, oil, or chemicals will be strictly enforced;
n
Only
well-maintained and inspected vessels would be used to limit any potential
discharges to the marine environment;
n
Safe storage,
handling and disposal of chemicals and oils to prevent the release into the
marine environment;
n
Bunding of
machinery areas and availability of spill clean-up kits would be in place to
prevent spillage or leakage of fuel/chemical to reach the marine environment;
n
The vessel
operators for the construction activities of this Project will be required to
use predefined and regular routes, make use of designated fairways to access
the active CMPs, and would avoid traversing sensitive habitats such as existing
and proposed marine parks. This measure
will further serve to minimise disturbance to Green Turtles and FP due to
vessel movements; and
n
The vessel
operators working on the construction activities of the Project will be given a
briefing, alerting them to the possible presence of FP in the active CMP areas,
and the guidelines for safe vessel operation in the presence of these
animals. The vessels will avoid using
high speed as far as possible. By
observing the guidelines, vessels will be operated in an appropriate manner so
that FP will not be subject to undue disturbance or harassment.
Recolonisation of
benthos is expected after capping of the CMPs and the habitats are expected to
return to pre-dredged conditions. With
the implementation of mitigation and precautionary measures during construction
and operation activities of the Project as mentioned in Section 4.9, potential
impacts on marine ecological resources will be further minimised. No
adverse residual impacts on marine ecological resources due to the dredging,
backfilling and capping works of the Project are expected.
As no unacceptable
impacts have been predicted to occur during construction and operation of the
Project, monitoring of marine ecological resources during these construction
and operation activities is not considered necessary.
Monitoring
activities designed to detect and mitigate impacts to water quality during
construction and operation activities are also expected to serve to protect
against impacts to marine ecological resources.
The details of the water quality monitoring programme will be presented
in the EM&A Manual attached to this EIA Report.
The EIA has
indicated that benthic fauna are expected to recolonise
the CMPs following capping with uncontaminated mud. It is expected that recolonisation of the
natural benthic assemblage will occur and eventually the benthic assemblage
will resemble that of the surrounding areas.
Recolonisation may be achieved by larval recruitment, influx of
juveniles or adults carried in water currents, or through the active swimming
or crawling of individuals. However,
other natural (e.g. storm events, hypoxia, salinity fluctuations) or
anthropogenic (e.g. pollution, fisheries operations) activities may hinder
recolonisation of capped pits. As a
result, the factors contributing to the composition of the benthic assemblage
may be difficult to determine. It is
also important for any recolonisation studies to be aware of any cap
maintenance (or "topping up") activities which may also impact the
resident benthic assemblages. In order
to verify the recolonisation of benthic assemblage on the capped CMPs, a
benthic recolonisation monitoring programme is recommended and the details will be presented in the EM&A
Manual attached to this EIA Report.
Based on literature
review and field survey findings, the key habitats within and in the vicinity
of the Project include coral and benthic communities and marine waters. Although FP are present in the vicinity of
the Project, their occurrence was
recorded to be consistently low over the past years and the area within and in
the vicinity of the Study Area is not a key habitat for FP. Marine
ecological resources in close proximity to the Project are regarded as of low
ecological values. The presence of
species of conservation importance such as Green Turtles in the Assessment Area
is very occasional.
The loss and
disturbance of subtidal habitats throughout the construction and operation
activities of the Project is considered as environmental acceptable to marine
ecological resources and marine mammals as the areas affected are relatively
small in the context of the extent of similar habitats available in the
vicinity and the low ecological value of the affected assemblages. Recolonisation of benthos is expected after
capping of the CMPs and the habitats are expected to return to pre-dredged
conditions. The temporary loss of these benthic assemblages of low ecological value
is not considered to be unacceptable. FP are expected to temporarily avoid the areas
of active CMPs, and would return upon cessation of the construction and
operation activities. With the
implementation of mitigation and precautionary measures including site
selection to avoid impacts to ecologically sensitive habitats as far as practicable,
proper planning and design of the CMPs, control of work rates for dredging,
backfilling and capping, briefing to vessel operators and the use of predefined
and regular routes, no unacceptable impacts are anticipated.
The impacts of
changes in water quality arising from the construction and operation activities
of the Project are predicted to be largely confined to the active CMP
areas. With the implementation of
mitigation measures, the predicted elevations of suspended sediment due to the
Project are not predicted to cause exceedances of the WQO at sensitive
receivers, unacceptable adverse impacts to water quality, and hence marine
ecological resources, FP, Green Turtles and the Potential South Lamma Marine
Park, are not anticipated. The assessment
of water quality impacts demonstrated that the marine ecological sensitive
receivers within the Assessment Area would not be unacceptably affected as
defined by the relevant assessment criteria.
The Project is expected to involve a
relatively small number of works vessels and the frequency/ trip of works
vessels would also be relatively low in general when comparing to the traffic
densities at the nearby fairways. Vessel
traffic associated with the proposed Project would represent only a minor
incremental increase in marine traffic in the area. Underwater sound and increase marine traffic
generated from the construction and operation activities are not expected to
result in unacceptable impacts to marine ecological resources, including FP and
Green Turtles, considering the relatively small number of works vessels and
trips involved, slow-moving nature of these vessels and the habituation of
similar sounds by the species in the current underwater soundscape.
The effects of glare
from light sources of construction and operation activities are considered to
be minor as the Project is located away from the Green
Turtle nesting ground at Sham Wan and shielded by the landmass at southwest of
Lamma Island. Accidental spill events at a scale that may
impact marine ecological resources are also extremely unlikely to occur, and precautionary measures will
be in place to reduce potential impacts.
The mitigation
measures designed to reduce impacts to water quality to acceptable levels
(compliance with WQOs) during construction and operation activities of the
Project are also expected to mitigate impacts to marine ecological resources,
FP, Green Turtles and the potential South Lamma Marine Park. With the implementation of mitigation and
precautionary measures during construction and operation activities of the
Project, potential impacts on marine ecological resources will be further
minimised. No adverse residual impacts on marine ecological
resources due to the dredging, backfilling and capping works of the Project are
expected.
([1]) AFCD
(2021) Monitoring of Marine Mammals in Hong Kong Waters (2020-2021). Prepared
by Hong Kong Cetacean Research Project.
([3]) EIA
Report for Improvement Dredging for Lamma Power Station Navigation Channel
(Register No.: AEIAR-212/2017)
([4]) AFCD
(2021) Monitoring of Marine Mammals in Hong Kong Waters (2020-2021). Prepared
by Hong Kong Cetacean Research Project.
([5]) Schoeman RP, Patterson-Abrolat C, Plon
S (2020). A Global Review of Vessel Collisions
With Marine Animals. Frontiers in Marine
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([6]) Witheringtom BE and Martin RE (2003)
Understanding, assessing and resolving light-pollution problems on sea turtle
nesting beaches. Third Edition. Florida Marine Research Institute Technical
Report TR-2 73pp.
([7]) Environmental Protection Authority
(2010) Environmental Assessment Guidelines No.5 Environmental Assessment
Guideline for Protecting Marine Turtles from Light Impacts.
([9]) Richardson WJ, Greene CR Jr., Malme
CI, Thomson DH (1995) Marine Mammals and Noise. Academic Press
([10]) Wang ZT, Li J, Duan PX, Mei ZG, Niu FQ,
Akamatsu T, Lei PY, Zhou L, Yuan J, Chen YW, Ya Supin A, Wang D, Wang KX (2020)
Evoked-potential audiogram variability in a group of wild Yangtze finless
porpoises (Neophocaena asiaeorientalis
asiaeorientalis). Journal of
Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral
Physiology 206(4):527-541.
([11]) Goold JC, Jefferson TA
(2002) Acoustic signals from free-ranging finless porpoises (Neophocaena phocaenoides) in waters
around Hong Kong. The Raffles Bulletin of Zoology Supplement
10:131-139.
([13]) Jones D, Marten K (2016) Dredging Sound
Levels, Numberical Modelling and EIA.
Terra et Aqua No. 144.
([14]) EGS (2017) Measurement of Underwater
Sound Levels around Submarine Cable Installation Barge. Prepared for CLP Power Hong Kong Limited
([15]) Robinson SP, Lepper PA, Hazelwood RA
(2014) Good Practice Guide for Underwater Noise Measurement. NPL Good Practice
Guide No. 133. National Measurement Office, Marine Scotland, The Crown Estate.
([16]) Jensen F, Kuperman W, MB P and Schmidt H
(2000) Computational Ocean Acoustics. Modern Acoustics and Signal Processing.
New York: Springer-Verlag.
([17]) Robinson SP, Theobald PD, Hayman G, Wang
LS, Lepper PA, Humphrey V, Mumford S (2011) Measurement of noise arising from
marine aggregate dredging operations. Marine Aggregate Levy Sustainability Fund
(MALSF). MEPF Ref no. 09/P108.
([18]) Considering shallow water depths in the
Project area, 15 log R law of
intermediate geometrical spreading was applied.
([19]) Southall BL, Finneran JJ, Reichmuth C,
Nachtigall PE, Ketten DR, Bowles AE, Ellison WT, Nowacek DP, Tyack PL
(2019). Marine Mammal Noise Exposure
Criteria: Updated Scientific Recommendations for Residual Hearing Effects. Aquatic Mammals 45(2): 125-232.
([20]) Parsons ECM, Jefferson TA (2000)
Post-mortem investigations on stranded dolphins and porpoises from Hong Kong
waters. Journal of Wildlife Diseases 36: 342-356
([21]) Jefferson TA, Curry BE, Kinoshita R
(2002) Mortality and morbidity of Hong Kong finless porpoises, with special
emphasis on the role of environmental contaminants. Raffles Bulletin of Zoology
(Supplement) 10: 161- 171
([23]) ERM (2021). Annual Risk Assessment Report for the
Contaminated Mud Pits to the East of Sha Chau - April 2020 to March 2021. Submitted under Agreement No. CE 63/2016
(EP).
([24]) Subject to further
investigation on the details of the proposed KYCAI development under the CW
Study, the detailed cumulative impacts to marine ecology due to habitat loss
and disturbance, increase in underwater sound, increase in marine traffic, if
any, will be addressed under the EIAs for the CW Study.