This Section presents the
findings of the marine ecological impact assessment associated with the
construction and operation of the Project.
It also summarises the key findings on the baseline ecological conditions,
the details of which are presented in Appendices
4A to 4C.
The criteria and
scope for evaluating marine ecological impacts are laid out in the Annexes 8
and 16 of the EIAO-TM and the Study Brief. Legislative requirements and evaluation
criteria relevant to this assessment are listed below. The details on each are
presented in Appendix 4A.
n
Marine Parks Ordinance (Cap.
476);
n
Wild Animals Protection
Ordinance (Cap. 170);
n
Protection of Endangered
Species of Animals and Plants Ordinance (Cap. 586);
n
Country Parks Ordinance (Cap.
208);
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 Chapter 10 (HKPSG); and
n
United Nations Convention on
Biodiversity (1992); and.
n
Peoples’ Republic of China
(PRC) Regulations and Guidelines.
In accordance with Clause 3.4.4.2
of the Study Brief, the Assessment Area for marine ecological impact assessment
(Figure
B1.1 of Appendix 4B) shall be the
same as the assessment area for Water Quality Impact Assessment covering the
Mirs Bay Water Control Zone (WCZ) and the Tolo Harbour and Channel WCZ. Detailed description of the physical
characteristics of the marine environment of the Assessment Area and compliance
of WQOs is provided in Section 3.
Marine ecological
important habitats and species within and in the vicinity of the Project site
as well as within the Assessment Area are evaluated, including existing marine
parks, horseshoe crab breeding and nursery grounds, mangroves, seagrass beds,
coral communities, marine benthos of conservation interest, and marine
ecological important species including Finless Porpoises (FPs), amphioxus and
horseshoe crabs. The marine ecological
profiles and characteristics of these habitats and species are described in
further details below. A habitat map on
the marine ecology of the Assessment Area is provided in Figure 4A.2.1 of
Appendix 4A.
A literature review was conducted to review the baseline marine
ecological conditions within the Assessment Area and to identify information
gaps to determine whether field surveys are required to provide sufficient
information for the marine ecological impact assessment. Findings of this literature review are
presented in detail in Appendix 4A.
Some of the baseline information was collected recently and is
considered to be up-to-date and representative of the existing conditions of
the Assessment Area. In accordance with
the requirements in Appendix C of the Study Brief, field 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 fill the
identified data gaps, verify and update the latest marine ecological conditions
of these habitats. The methodology for
the field surveys is presented in Appendix
4B. Field survey findings
are presented in detail in the following sections.
Marine
ecological surveys were conducted in Wong Chuk Kok Hoi in accordance to the
methodology as stated in Appendix
4B. Surveys were conducted from September 2020 to
February 2021 and the details are summarised in Table 4.1.
Table
4.1 Marine Ecological Baseline Surveys
|
Survey |
Season & Date |
|
Subtidal Benthos Survey |
Wet Season: 25 Sep 2020, 21 Oct 2020 Dry Season:
26 Jan 2021, 1 Feb 2021 |
|
Coral Survey |
17 Nov 2020 |
|
Drop Camera Survey |
28 Dec 2020 |
A total of 38 individual
organisms were collected from the five grab samples from Wong Chuk Kok Hoi
during the wet season survey (Figure B2.3 of Appendix
4B). The specimens belong to 4 Phyla with
a total of 4 classes,
6
families and 7
species identified. Table
4.2 provides a
summary on the abundance, biomass, taxonomic richness, Pielou’s Evenness and
Shannon Diversity of infauna collected at each location. A complete set of raw data is presented in Table
4C.1 of
Appendix
4C.
Results of the wet season survey
showed that infaunal abundance, biomass and taxonomic richness (here
represented by number of families and species of infaunal organisms) were low
and were lower than that in dry season in general (Table
4.2
and Table
4.3). In terms of infaunal abundance, the majority
(~87%) of organisms recorded were from the Phylum Annelida. The polychaete worm, Sigambra hanaokai was the most abundant species (total abundance = 19 individuals). The Amphioxus, Branchiostoma belcheri, was recorded in the survey at sites WCKH1
and WCKH2 with low abundance (total abundance = 3 individuals).
In terms of infaunal biomass, organisms from the Phyla Mollusca, Annelida and Chordata contributed
significant biomasses (~39%, ~34% and ~27% respectively). The high biomass of Mollusca was contributed by 1 scaphopod species, Episiphon
kiaochowwanense.
A total of 541 individual organisms were
collected from the five grab samples during the dry season survey. The specimens belong to 5 Phyla with a total of 6 classes, 17 families and 24 species identified. Table
4.3 provides
a summary on the abundance, biomass and taxonomic richness of infauna collected
at each location. A complete set of raw
data is presented in Table 4C.2 of Appendix 4C.
Results of the dry season
survey showed that infaunal abundance, biomass and taxonomic richness (here
represented by number of families and species of infaunal organisms) were
relatively high comparing to wet season (Table
4.2
and Table
4.3). In terms of infaunal abundance, the majority
(~84%) of
organisms recorded were from the Phylum Annelida. The polychaete worms Sigambra hanaokai was the most abundant species (total abundance = 162 individuals). No species of conservation interest were
recorded in the dry season survey. In
terms of infaunal biomass, organisms from the Phylum Mollusca contributed ~73% of the total biomass recorded,
while organisms from Annelida
also contributed significant biomasses (~27%).
The high biomass of Mollusca
was contributed by a number of species,
primarily by a bivalve species, Nitidotellina lischkei.
Table 4.2 Density and Indices of Richness, Evenness and Diversity
of Infaunal Assemblages at the Sampling Locations for the Soft Bottom Habitat
Surveys at the Assessment Area during the Wet Season
|
Station |
Number of
Infaunal Individuals |
Number of Individuals per m2 |
Taxonomic Richness (No. Families) |
Taxonomic Richness (No. Species) |
Pielou’s Evenness (J)(Note1) |
Shannon Diversity (H’) |
Total Biomass (g wet weight) |
Mean Biomass per Individual (g wet weight) |
|
WCKH1 |
7 |
72.92 |
4 |
4 |
0.92 |
1.28 |
0.0200 |
0.0029 |
|
WCKH2 |
1 |
10.42 |
1 |
1 |
**** |
0.00 |
0.0009 |
0.0009 |
|
WCKH3 |
21 |
218.75 |
2 |
3 |
0.94 |
1.04 |
0.0122 |
0.0006 |
|
WCKH4 |
7 |
72.92 |
3 |
3 |
0.87 |
0.96 |
0.0306 |
0.0044 |
|
WCKH5 |
2 |
20.83 |
1 |
1 |
**** |
0.00 |
0.0011 |
0.0006 |
Note:
(1) Pielou’s
Evenness cannot be calculated for sites WCKH2 and WCKH5, as the taxonomic
richness (no. of species) is 1.
Table 4.3 Density
and Indices of Richness, Evenness and Diversity of Infaunal Assemblages at the
Sampling Locations for the Soft Bottom Habitat Surveys at the Assessment Area
during the Dry Season
|
Station |
Number
of Infaunal Individuals |
Number
of Individuals per m2 |
Taxonomic
Richness (No. Families) |
Taxonomic
Richness (No. Species) |
Pielou’s
Evenness (J) |
Shannon
Diversity (H’) |
Total
Biomass (g wet weight) |
Mean
Biomass per Individual (g wet weight) |
|
WCKH1 |
110 |
1145.83 |
11 |
15 |
0.76 |
2.05 |
0.5054 |
0.005 |
|
WCKH2 |
86 |
895.83 |
12 |
15 |
0.77 |
2.09 |
0.9951 |
0.012 |
|
WCKH3 |
40 |
416.67 |
11 |
12 |
0.84 |
2.09 |
0.1297 |
0.003 |
|
WCKH4 |
122 |
1270.83 |
11 |
14 |
0.78 |
2.06 |
0.7088 |
0.006 |
|
WCKH5 |
183 |
1906.25 |
9 |
13 |
0.79 |
2.02 |
0.9643 |
0.005 |
During
the surveys, the weather was fine and the sea was calm. The visibility was however poor and generally
ranged between 0.5 m and 2 m. The
general substrata and biological conditions noted along each transect during
the qualitative spot dive reconnaissance check are presented in Table 4.4.
Table
4.4
Description of the Seabed Recorded
along Each Transect during the Qualitative Surveys (Spot Dive Reconnaissance
Check Surveys)
|
Transect |
Depth |
Description |
|
T1 |
-3 to - 6 mCD |
The seabed was mainly composed of boulders in shallow water (-3 to - 4
mCD) and sandy / silty substrate in deep water (-5 to -6 mCD). Sparse hard coral colonies, such as Porites sp., Oulastrea crispata, Bernardpora
stutchburyi and Psammocora
profundacella were identified in shallow and deep waters. |
|
T2, T3 |
-3 to -7 mCD |
The sites were mainly composed of sand in both shallow water (-3 to -4
mCD) and deep water (-5 to -7 mCD).
More coral species were identified at T2 at shallow water, while more
coral species were identified at deeper water at T3. A high number of Platygyra carnosa was recorded in shallow waters of T2 but absent
in T3. |
Transects
are located at North (T1) and South (T2 and T3) natural shores of Wong Chuk Kok
Hoi (Figure
B2.1 of Appendix 4B). The site mainly comprised of large boulders,
sand and mud. On the hard substrata,
sessile benthos primarily comprised of isolated barnacles. Only sparse colonies of hard coral (<5% -
10%), macroalgae (<5%) and other benthos (<5%), such as sea anemones and
sponges, were identified (Table 4C.3 of Appendix
4C).
A total of twenty-seven hard corals, three species of sea anemones and one sponge
species were identified (Table
4C.4 of Appendix 4C).
The majority of corals recorded
were common and widespread species in Hong Kong, including Porites sp., Oulastrea crispata and Platygyra carnosa. Octocoral and black corals were not recorded
at the surveyed transect. Representative
photos of the seabed and coral conditions during the surveys are presented in Figure 4.1.
Overall,
results of the dive surveys indicated that the subtidal hard substrate of the
Assessment Area showed limited sessile taxa.
Common and widespread corals were recorded in low percentage cover
(<10%) in both shallow and deep waters.
Drop camera surveys were
conducted at Wong Chuk Kok Hoi at the survey locations shown in Figure B2.1 of Appendix
4B. A total of five stations were surveyed within
the Project site with the use of a drop camera system to record the benthic
attributes by positioning the system ~1 m above the seabed. The results showed that the seabed at the
survey locations (~-15 mCD) consisted of silty mud without any hard substrate
and benthic organisms recorded.
Representative photos extracted from the video footages are presented in
Figure
4.2a and Figure
4.2b.
The key findings of the literature
review and field surveys are summarised below.
Recognised sites of
conservation importance within the Assessment Area include Country Parks,
Special Areas, Marine Parks, and Sites of
Special Scientific Interest (SSSI). Some
of these which are relevant to marine ecology and are located in the Assessment
Area are discussed below.
The existing country parks in
the Assessment Area include the Plover
Cove Country Park and Plover Cove (Extension) Country Park. Plover Cove Country Park was designated in
1978 with an area of 4,594 ha and have terrestrial conservation interest. Plover Cove (Extension) Country Park was
designated on 1979 covering several islands in the northeastern waters
including Tung Ping Chau, Port Island, Double Heaven and Crooked Island. Some of these islands were also known to have
nested with White-bellied Sea Eagles (Haliaeetus leucogaster). However, as both country parks are of
terrestrial conservation interest, it is considered that the
impact of the Project on these country parks are not anticipated. Locations of the country parks are provided
in Figure
4A.2.1 of Appendix 4A ([1]).
The existing special
area in the Assessment Area is the Double Haven Special Area located at ~3 km
from the Project site. Double Haven
Special Area was designated in 2011 with an area of 0.8 ha and mainly of
geological interest. As Double Haven
Special Area does not have major marine ecological related interest, it
is considered that the impact of the Project on the site is not
anticipated. Location of the special
area is provided in Figure 4A.2.1 of Appendix 4A ([2]).
Yan Chau Tong Marine Park (YCTMP)
and Hoi Ha Wan Marine Park (HHWMP) are the existing marine parks within the
Assessment Area. No proposed or
potential marine parks are identified within the Assessment Area. Details of the marine parks are provided in Table
4A.2.1 of Appendix 4A. Locations of the marine parks are provided in
Figure
4A.2.1 of Appendix 4A ([3]).
Tolo
Channel (Northern Coast) SSSI and Hoi Ha Wan SSSI are the SSSIs within the
Assessment Area. However, Tolo Channel
(Northern Coast) SSSI located nearest to the Project site is of geological
interest and therefore is considered not affected by the Project works which
are all marine based. Ho Ha Wan SSSI is
located at 2.8 km away from the Project site, which is considered to be far
away to be affected by the Project.
Details of the SSSI are provided in Table
4A.2.1 of Appendix 4A. Locations of the SSSIs are provided in Figure 4A.2.1 of Appendix 4A ([4]).
According to
the latest AFCD Marine Mammal Monitoring Report 2021/22, no records of Hong
Kong’s resident marine mammal species, the Finless Porpoise, Neophocaena phocaenoides and the Chinese
White Dolphin (CWD) Sousa chinensis
was reported in the Assessment Area. Considering the Project site located at the northeastern
waters in Wong Chuk Kok Hoi while CWDs in Hong Kong are mainly distributed at
western and southwestern Lantau waters and FPs are mostly distributed in the
southern and eastern waters of Hong Kong, the impact to marine mammals from the
Project is therefore not anticipated.
The distribution of FPs in Hong Kong waters is provided in Figure 4A.2.4 of Appendix 4A ([5]).
Two species of horseshoe crab, Tachypleus tridentatus and Carcinoscorpius rotundicauda, have
previously been recorded around Hong Kong waters. Based on the abundance of juveniles, Luk Keng
and Sha Tau Kok are identified as the key nursery grounds for C. rotundicauda and T. tridentatus. Adult
horseshoe crabs are not recorded in the northeastern waters of Hong Kong. The nearest records of occurrence were from
the beaches in Lai Chi Wo in YCTMP which is located out of the Assessment Area (Figure 4A.2.1 of Appendix
4A), therefore, the impact of the Project on horseshoe
crabs is not anticipated.
Four mangrove stands are found in
the Mirs Bay FCZ and one mangrove stand is found in the Tolo Harbour and
Channel WCZ within the Assessment Area.
No mangrove stands are found within the Project Site. The nearest mangrove stand from the Project
site is located at Tung Wan which is ~1 km away. The site is considered to be far away from
the Project site and the impact of the Project on mangroves is therefore not
anticipated. Locations
of the mangroves are provided in Figure 4A.2.1 of Appendix 4A
([6]).
Coral
communities in the eastern waters of Hong Kong generally have a higher
diversity and abundance as the surrounding marine environment is less
influenced by the Pearl River outflow compared to the western waters of Hong
Kong with lower salinity and higher turbidity ([7]). Literatures have reported that hard coral,
octocoral and black coral were recorded at Wong Chuk Kok Tsui (south coast at
the mouth of Wong Chuk Kok Hoi) and early studies reported that a coral
coverage of 10 – 50% is found at Wong Chuk Kok Hoi. Recent surveys including those conducted
during Reef Check 2021 have also recorded 10.4% coral coverage at Wong Chuk Kok
Hoi. Locations
of the coral communities are provided in Figure 4A.2.1 of Appendix 4A
([8]) ([9]) ([10]).
Results of the
Feasibility Study of this Project has revealed that coral communities were
sparse with low coverage (<5%), except from shallow areas in the northern
shoreline of Wong Chuk Kok Hoi (~200m away from the Project site) which the
hard coral coverage was 11 – 30%. A
total of 34 hard coral species and one octocoral species were identified in
Wong Chuk Kok Hoi during these surveys.
The species identified during the survey were generally regarded as
common and widespread species in Hong Kong waters, apart from some uncommon
corals; Montipora mollis, Galaxea astreata, Acanthastrea echinata,
Cyphastrea chalcidicum, Favites flexuosa, Goniopora djiboutiensis and Psammocora
haimiana.
Field surveys were
conducted to fill in the information gap of the Feasibility Study, with
findings showing that the
majority of corals recorded were common and widespread species in Hong Kong,
including Porites sp., Oulastrea crispata and Platygyra carnosa. Octocoral and black corals were not recorded
at the surveyed transect. Overall, the
coral coverages at the surveyed areas in both shallow and deep waters were low
(<10%). Results of drop
camera survey also showed that the seabed of this site (~15 mCD) was dominated
by silty mud without any hard substrate or benthic organisms.
Amphioxus
are mostly present within Hong Kong’s eastern waters, with densities ranging
from 10 to 400 ind / m2 predominantly at sites in Tai Long Wan, Nam
She Wan, Long Ke Wan and Pak Lap Wan off the Sai Kung Peninsula ([11]).
However, no studies have been conducted at the Project site
previously. Field surveys were conducted
to fill in this information gap. From
the baseline subtidal benthos survey, very low numbers of
amphioxus, Branchiostoma belcheri were
found within the Project site during the wet season.
Other intertidal and subtidal benthos species reported
in the Assessment Area from the field surveys and literature review are common
and widespread in Hong Kong with no species of conservation importance. As the
Project site is located away from the shorelines, the assessment on intertidal
hard bottom assemblages is considered not necessary. Potential marine ecological impact would
occur mostly on the subtidal environment and the impact on intertidal habitats
is not anticipated.
There are studies
which showed that benthic communities at northeastern waters, Tolo Channel and
western Mirs Bay overlapping with the Assessment Area were impoverished. None of these species is unique to a
particular location of the Assessment Area, and many of these species were also
reported elsewhere in Hong Kong waters. Marine Eel Grass (Zostera japonica),
with high ecological value was reported to be abundant
at the Lai Chi Wo Beach, however, as it is located out of the Assessment Area,
therefore, the impact of the Project on the seagrass is not anticipated.
Findings of
white-bellied sea eagle (WBSE) was spotted on Crooked Island and Port Island
within the Assessment Area, located both >3 km away from the Project
site. It was reviewed from literature
and previous field surveys that the species is uncommon but widespread in Hong
Kong. As the nesting grounds of WBSE is
far away from the Project site and that the foraging distance generally reaches
2 km from their nesting location, the
impact of the Project on the WBSE is therefore not anticipated. Locations
of the WBSE nesting grounds are provided in Figure 4A.2.1 of Appendix 4A
([12]).
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, focused
field surveys and data review to update and supplement the data. Based on this information presented in Section 4.3.2, Section 4.3.3, Appendices 4A and 4C, the ecological importance of each habitat has been determined
according to the EIAO-TM Annex 8
criteria.
Within the Assessment Areas
(mainly marine ecology) 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 focused on the vicinity of
the works areas of the Project site.
The ecological importance of
the habitats was determined through reference to the following:
n
Literature review;
n
Findings of the field 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
Areas are presented in Tables 4.5 to 4.9.
Table 4.5 Marine
Ecological Importance of Existing Marine Parks and SSSIs within the Assessment
Area
|
Criteria |
Yan Chau Tong Marine Park (YCTMP) |
Hoi Ha Wan Marine Park (HHWMP) |
Tolo Channel (Northern coast) SSSI |
Hoi Ha Wan SSSI |
|
Naturalness |
Natural intertidal and subtidal hard and
soft bottom habitat and marine waters |
Natural intertidal and subtidal hard and
soft bottom habitat and marine waters |
Natural land mass with rocky shoreline
consisting of sedimentary rock |
Natural intertidal and subtidal hard and
soft bottom habitat and marine waters |
|
Size |
~680 ha |
~260 ha |
~1,287 ha |
~278 ha |
|
Diversity |
Moderate |
Moderate |
Low |
Moderate |
|
Rarity |
Habitat and species are uncommon in the
northeastern water of Hong Kong.
Species with conservation importance, included the main assemblages of
seagrass Zostera japonica, hermatypic
hard coral and ahermatypic cup coral |
Habitat and species are uncommon in the
northeastern water of Hong Kong.
Species of conservation importance including numerous species of
hermatypic hard coral, ahermatypic cup coral, black coral, and octocoral |
No documented marine ecological importance
associated with the SSSI |
Habitat and species are uncommon in the
northeastern water of Hong Kong.
Species of conservation importance including numerous species of
hermatypic hard coral, ahermatypic cup coral, black coral, and octocoral |
|
Re-creatability |
Not re-creatable |
Not re-creatable |
Not re-creatable |
Not re-creatable |
|
Fragmentation |
Made up of two portions, 1 km apart |
Unfragmented |
Unfragmented |
Unfragmented |
|
Ecological Linkage |
Linked to the intertidal, subtidal habitats
and seagrass bed |
Linked to the intertidal and subtidal
habitats |
Not functionally linked to any high value habitat in a significant way |
Linked to the intertidal and subtidal
habitats |
|
Potential Value |
Already designated as marine park |
Already designated as marine park |
Already designated as a SSSI |
Already designated as a SSSI |
|
Nursery / Breeding Area |
Nursery grounds for juvenile of fishes and
other marine invertebrates |
Nursery grounds for juvenile of fishes and
other marine invertebrates |
Key known nesting ground for green turtle |
Nursery grounds for juvenile of fishes and
other marine invertebrates |
|
Age |
Designated as marine park in July 1996 |
Designated as marine park in July 1996 |
Designated as SSSI and Restricted Area in
September 1982 |
Designated as SSSI in January 1989 |
|
Abundance |
First local site of observing seagrass Zostera japonica in Hong Kong. Abundance of seagrass Zostera japonica is high |
Historically high abundance of hard
coral. Old coral colonies and regarded
as location of considerable carbonate accumulation |
No documented abundance of marine
ecological species associated with the SSSI |
Historically high abundance of hard coral. Old coral colonies and regarded as location
of considerable carbonate accumulation |
|
Ecological
Importance |
High |
High |
Moderate
|
High |
Table
4.6 Ecological Importance of Intertidal Habitats in the vicinity of the Project site
|
Criteria |
Soft Bottom Intertidal Habitat |
Hard Bottom Intertidal Habitat |
Artificial Intertidal Habitat |
|
Naturalness |
Natural habitat |
Natural habitat |
Artificial |
|
Size |
Small, only small patches of sandy shore recorded |
Large, majority of the shoreline within and in the vicinity of the Project site |
Small, comprise of small piers and seawall |
|
Diversity |
Low |
High |
Low |
|
Rarity |
Ghost crab (Ocypode cordimana,
previously known as Ocypode cordimanus),
oligochaete worms (Heronidrilus bihamis)
and starfish Luidia longispina were
recorded. No rare species found |
Common rocky shore flora and fauna were recorded e.g. seaweeds Ulva lactuca, Colpomenia sinuosa, short-spined sea urchin Heliocidaris crassispina |
Not surveyed in the literature reviewed, it is assumed that the
assemblages comprise common
and widespread intertidal species in Hong Kong like Barnacle Balanus amphitrite, Bivalve Grafrarium
pectinatum, and snails Nassarius
festivus, Monodonta labio, Batillaria multiformis, B. zonalis |
|
Re-creatability |
Re-creatable; substrata may be re-colonised by intertidal and subtidal
organisms |
Not re-creatable |
Re-creatable; substrata may be re-colonised by intertidal and subtidal
organisms |
|
Fragmentation |
Fragmented |
Unfragmented |
Fragmented |
|
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 |
Unlikely to become an area of conservation value |
Unlikely to become an area of conservation value |
Unlikely to become an area of conservation value |
|
Nursery / Breeding Area |
No significant records identified |
No significant records identified |
No significant records identified |
|
Age |
N/A |
N/A |
N/A |
|
Abundance |
Lower abundance compared to natural rocky shore habitat |
Low abundance |
Lower abundance compared to natural rocky shore habitat |
|
Ecological
Importance |
Low |
Low |
Low |
Table
4.7
Ecological Importance of Subtidal
Hard-Bottom Habitats within and in the vicinity of the Project site
|
Criteria |
Wong Chuk Kok Hoi |
Yan Chau Tong Marine Park (YCTMP) |
|
Naturalness |
Natural |
Natural |
|
Size |
Large. Subtidal area of the northern and southern
shoreline of Wong Chuk Kok Hoi, including Wong Chuk Kok Tsui is about 3 km |
Large. ~680 ha |
|
Diversity |
Low to Moderate |
High |
|
Rarity |
Assemblages comprise typical common and widespread species in Hong
Kong, except Montipora mollis,
Galaxea astreata, Acanthastrea echinata, Cyphastrea chalcidicum, Favites
flexuosa, Goniopora djiboutiensis and Psammocora haimiana. ‘Old corals’ were documented in the vicinity |
Habitats and species are uncommon in the northeastern water of Hong
Kong. Species with conservation
importance, included the main assemblages of seagrass Zostera japonica, hermatypic hard coral and ahermatypic cup coral |
|
Re-creatability |
The habitat can be
recreated through the deployment of artificial reefs or through rubble mound
/ rock armour seawalls |
Not re-creatable |
|
Fragmentation |
Unfragmented |
Made up of two portions, 1 km apart |
|
Ecological Linkage |
Not functionally linked to any high value habitat in a significant way |
Linked to seagrass bed and mudflats and horseshoe crab habitats in
inner Starling Inlet |
|
Potential Value |
Generally low since
it is a common natural habitat with low coral coverage. Wong Chuk Kok Tsui has higher ecological
interest with the presence of diverse hard corals and medium coverage of Antipatharia
recorded |
Already designated as marine park |
|
Nursery / Breeding Area |
No significant records identified |
Nursery grounds for juvenile of fishes and other marine invertebrates |
|
Age |
Hard corals are
known to be long lived and some recorded old corals are likely to be more
than 60 years old |
Designated as marine park in July 1996 |
|
Abundance |
Low coral coverage
(<10%) in general, except for some shallow areas at northern shoreline of
Wong Chuk Kok Hoi with 11-30% coverage; and moderate abundance of hard corals
and Antipatharia recorded at Wong Chuk Kok Tsui |
First local site of observing seagrass Zostera japonica in Hong Kong. Abundance of seagrass Zostera japonica is high |
|
Ecological Importance |
In general low; moderate to high near Wong Chuk
Kok Tsui |
High |
Table
4.8 Ecological
Importance of Subtidal Soft Benthos Assemblages within the Project site
|
Criteria |
Wong Chuk Kok Hoi |
|
Naturalness |
Natural |
|
Size |
~35 ha |
|
Diversity |
Low |
|
Rarity |
The assemblages are
typical of similar habitats in the Hong Kong waters, which are dominated by
polychaetes. Scarce amount of
amphioxus (lancelet) Branchiostoma
belcheri was recorded in wet season |
|
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 eastern waters the assemblages are of low to moderate abundance
and biomass |
|
Ecological Importance |
Low |
Table
4.9 Ecological
Importance of Marine Waters
|
Criteria |
Waters in Wong Chuk Kok Hoi and in the vicinity |
|
Naturalness |
Natural |
|
Size |
~35 ha |
|
Diversity |
Potential sighting of FP
but rarely present |
|
Rarity |
FP is a resident species
in Hong Kong. Commonly observed in eastern waters but not in northeastern
waters of Hong Kong |
|
Re-creatability |
Not re-creatable |
|
Fragmentation |
Unfragmented. |
|
Ecological Linkage |
Linked to FP and marine
habitat nearby |
|
Potential Value |
It is unlikely that the habitat
could develop conservation importance |
|
Nursery / Breeding Area |
No significant records
identified |
|
Age |
N/A |
|
Abundance |
Very low density of FP in
comparison to other waters of Hong Kong |
|
Ecological Importance |
Low |
In accordance with EIAO-TM
Annex 8 criteria, an evaluation of species of conservation importance
recorded from 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 |
|
Hard
Corals (>40 spp.) |
Duncanopsammia peltata, Oulastrea
crispata Porites sp., etc. |
Protection of
Endangered Species of Animals and Plants Ordinance (Cap.586) |
Majority
are common and widely distributed in the eastern waters of Hong Kong, with a
few uncommon species |
ü |
ü |
In
the vicinity of the Project site and throughout northeastern waters of Hong
Kong, such as Port Island and Tolo Channel both located at >3 km from the
Project site |
|
Black
corals |
Antipathes sp., Cirripathes sp. |
Protection of
Endangered Species of Animals and Plants Ordinance (Cap.586) |
Common
but sparsely distributed in the north-eastern waters of Hong Kong |
ü |
|
Wong
Chuk Kok Tsui, South Wong Chuk Kok Tsui and Port Island located ~1.3 km, ~1.5
km and ~3.3 km from the Project site respectively |
|
Octocorals |
Echinomuricea sp., Dendronephthya sp., Euplexaura sp. |
Protection of
Endangered Species of Animals and Plants Ordinance (Cap.586) |
Common
but sparsely distributed in the eastern waters of Hong Kong |
ü |
|
One
species is recorded within Wong Chuk Kok Hoi and at Wong Chuk Kok Tsui (~1.3
km away). Other species are recorded
at South Wong Chuk Kok Tsui located at ~1.5 km from the Project site |
|
Amphioxus |
Branchiostoma belcheri |
Listed as “Grade II National Key Protected Species” in China Listed as “Endangered” in the China Species Red List |
Recorded
from across Hong Kong waters, but major records were found in eastern waters |
ü |
ü |
Within
Project site and mostly present within Hong Kong’s eastern waters, such as
Nam She Wan and Tai Long Wan in Sai Kung |
|
White-bellied
Sea Eagle |
Haliaeetus leucogaster |
Listed in Wild Animals Protection Ordinance (Cap. 170) Listed in Protection of Endangered Species of Animals and Plants
Ordinance (Cap. 586) Class II Protected Animal of PRC Listed as Regional Concern in Fellowes et al. (2002) |
Uncommon
resident. Widely distributed in coastal areas throughout Hong Kong |
ü |
|
Nesting
ground recorded on Crooked Island and Port Island located at ~4.1 km and ~3.3
km from the Project site respectively |
Based on the review of available
information within the Assessment Area, marine ecological sensitive receivers
have been identified in accordance with the EIAO-TM
criteria. These sensitive receivers and
their distance from the Project site are listed in Table 4.11.
Locations of sensitive receivers
can be referred to Figure 4A.2.1 of Appendix 4A.
Table
4.11 Approximate Shortest Distance to Marine
Ecological Sensitive Receivers (SRs) around the Project site
|
|
Name |
Shortest Separation
(Geodesic) Distance (km) |
|
Corals |
NE Crooked Island (CR1) |
4.1 |
|
Crescent Island and Double Island (CR2) |
0.8 |
|
|
Port Island (CR3) |
3.3 |
|
|
Wong Wan Tsai (CR8) |
3.1 |
|
|
Fung Wong Wat (CR9) |
2.1 |
|
|
Gruff Head (CR10) |
2.6 |
|
|
South Wong Wan Tsui (CR11) |
0.9 |
|
|
Wong Chuk Kok Tsui (CR12) |
1.3 |
|
|
Hoi Ha Wan Moon Island (CR13) |
3.4 |
|
|
Hoi Ha Wan Coral Beach (CR14) |
4.0 |
|
|
Sam Mun Shan (CR15) |
4.9 |
|
|
Heung Lo Kok (CR16) |
3.1 |
|
|
Mangrove Stand / Intertidal Habitat |
Ngau Shi Wu Wan (M1) |
4.1 |
|
Ngor Tau Tsui (M2) |
4.5 |
|
|
Tung Wan (M3) |
1.0 |
|
|
Sam A Chung (M4) |
4.5 |
|
|
Fung Wong Wat (M5) |
2.3 |
|
|
Designated Marine Park |
Yan Chau Tong Marine Park and Artificial
Reef within the Marine Park (MP1) |
1.1 |
|
Hoi Ha Wan Marine Park and Artificial Reef
within the Marine Park (MP2) |
2.7 |
|
|
Designated SSSI |
Hoi Ha Wan SSSI (SSSI1) |
2.8 |
The Method Statement on Marine Ecological Impact Assessment for Wong Chuk Kok
Hoi Fish Culture Zone under this assignment was approved on 12 October 2020
and is presented in Appendix 4B. 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 marine
ecological resources identified within the Assessment Areas was evaluated using
the methodology defined in the EIAO-TM.
Potential impacts to these resources due to the
construction and operation 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 are used, where appropriate, to assess potential impacts on the
identified marine ecological resources.
The construction of the proposed
Project will mainly involve the setup of fish farm structures, including fish rafts
/ cages, auxiliary facilities and mooring system. No dredging works is required during the
construction phase.
The scale of construction work
on-site is relatively small. Main
components of the rafts / cages are manufactured off-site and will be towed to
the Project site using tug boat. On-site
assembly and anchoring of the fish rafts / cages will be assisted by a small
number of marine vessels such as sampans and small speed boats for up to a few
trips per day. Anchoring of these
vessels might be required. No heavy
construction plant would be used. Fish
rafts / cages and auxiliary facilities, such as storage space and shelters,
would be positioned by anchor lines attaching to the anchorage points on the
seabed. Use of winch might be required during
the assembly and anchorage of fish rafts/ cages. All construction activities shall be
conducted during daylight hours.
Potential impacts to marine
ecological resources arising from these works may be divided into those related
to:
n
Disturbance of marine habitats; and
n
Underwater sound from marine
construction activities and marine vessels.
Direct impacts to marine
ecology include disturbance caused by assembly and installation activities
on-site. The installation of fish farm structures are expected to be completed
within a few weeks for each fish raft, and would cause temporary
disturbance to marine habitats, such as marine waters with an area of
approximately 35 ha and small area of benthic habitats. Fish farm structures, such as fish cages will
occupy a section of the water column and the disturbance of seabed due to the
anchorage of fish farm structures will be
confined to a thin surface layer (<0.5 m) within a small area. It should be noted that only a small number
of vessels will be used and the frequency / trip of these vessels would also be
relatively low. No disturbance to other marine
ecological sensitive receivers, including YCTMP and
HHWMP which are located ~1.1 km away and ~2.7 km away respectively, is expected.
Within the Project site, the
seabed composition was found to mainly consist of silty mud without any hard
substrate, with benthic assemblages dominated by polychaete
worms and characterised by similar species diversity and biomass as elsewhere
in Hong Kong. Although a species of
conservation importance (i.e. the amphioxus, Branchiostoma belcheri) was recorded
within the Project site, only very low abundance of the species was
recorded. The overall coral coverage is
considered low and other species are considered to occur frequently in Hong
Kong. Overall, the
subtidal habitats within the Project site were considered as of low ecological
importance. Similar habitats are present the surrounding areas and the disturbance
would represent a very small fraction of the widely available habitat.
Considering the temporary
nature of the disturbance (a few weeks for each fish raft / cage), the small
extent of area affected and low ecological importance of the affected area,
impacts are considered to be of minor significance and unacceptable impacts on marine
ecological resources are not expected. Marine ecological
resources are expected to return to the area following the cessation of fish
farm construction activities.
Construction activities, such as during the assembly of
fish raft, would generate noise, glare and dust which may affect marine
ecology. Potential impacts to marine
life, mostly fish species, would have temporary avoidance of areas in the
vicinity of works area or close to the source of disturbance. Considering the
temporary nature of the construction works, impacts from the generation of
noise, glare and dust on marine habitats are considered negligible,
and unacceptable impacts on the marine ecological resources are not
anticipated. Major lighting sources will be pointed inward and
downwards to avoid disturbance to wildlife, unacceptable
impacts on the marine ecological resources are not anticipated.
Intermittent sounds, which occur during assembly
and installation activities on-site 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.
Therefore, underwater sound generated from marine works is expected to
have negligible impact on marine invertebrates in the Assessment Area.
The impact of underwater sound generation from
construction activities on fish is highly depended upon the hearing
capabilities of the different species present in the area, with the hearing
specialists being of greatest concern.
The significance of these effects is dependent upon the proximity of
fish to the sound source. Considering
that a small number of marine vessels would be present temporarily at the
Project site during fish farm construction, fish species that are sensitive to
the generation of sound are likely to instinctively avoid the area once works
commence and would be temporarily displaced to other areas where similar
habitat conditions are present.
Fishes are
expected to return to the area following the cessation of fish farm
construction activities.
Waters within the Assessment Area
and its vicinity is subject to moderate to high levels of marine traffic by
similar types of vessels. It is
reasonable to assume that marine organisms are habituated to background level
of underwater sound, and a small increase in vessel activity associated with the
construction of this Project is not anticipated to result in unacceptable
impacts on marine organisms at and in the vicinity of the Project site. Overall, unacceptable impacts on marine
ecological resources are not expected.
Mariculture activities, such as
management of fish raft / cages and fish stocks within the Project site will be
undertaken during operational phase.
Limited numbers of small power generators will be used on fish rafts to
support daily mariculture activities.
The transportation of fish stocks, fish feed, fish raft equipment and
workforce as well as occasional visitors will make use of mainly small marine
vessels such as sampans and speed boats for a few trips a day. No maintenance dredging or sediment removal
is anticipated during FCZ operation.
All operation activities shall be conducted during daylight hours. The potential impacts on marine ecology of
the Assessment Area include:
n
Changes in marine habitats (marine
waters and benthic habitat);
n
Temporary relocation of rafts under
typhoons or algal blooms;
n
Underwater sound from daily
operations and marine vessels;
n
Perturbations to key water quality
parameters during fish farm
operation, including fish feed wastage, fish excretion and dead fish; and
n
Introduction of invasive species.
As discussed in Section
4.5.1.1, the fish farm structures will not fully occupy all of the
Project site area but mainly a section of the water column and a small area of
seabed confined to a thin surface layer
(<0.5 m), the area of marine ecological habitat affected is
<35 ha. The small extent of area affected which is of low ecological importance,
impacts are considered to be of minor significance and unacceptable impacts on
marine ecological resources are not expected.
Fish rafts / cages and anchoring
equipment would provide hard substrate for the settlement of epifaunal
organisms that would not otherwise be successful in colonising the area. Where permitted, colonisation of the
structures over time is expected to lead to the development of a marine fouling
community. Effects associated with
creation of artificial habitat may include increased biological productivity
and increased diversity of habitats.
Overall, the structures of the fish farm are expected to result in
potential positive effect on marine ecological resources of the waters within
and in the vicinity of the Project site.
All the fish rafts / cages will be
floating with permeable nets to allow water exchanges with the marine
environment. Consequently, it is
predicted that no unacceptable changes in hydrodynamics will occur.
Operational
activities, such as cleaning of
fish cages and the use of lighting, would generate noise, glare and dust
which may affect marine ecology.
Potential impacts to marine life, mostly fish species, would include
temporary avoidance of areas in the vicinity of works area or close to the
source of disturbance. Considering the temporary nature of the cleaning
activities, impacts from the generation of noise, glare and dust on marine
habitats are considered negligible, and unacceptable impacts on the marine
ecological resources are not anticipated.
Major lighting sources will be pointed inward and downwards to avoid
disturbance to wildlife, unacceptable impacts on the marine ecological
resources are not anticipated.
In general, relocation of fish
rafts adopting advanced mariculture technologies are not necessary under
adverse weather (e.g. typhoon) given the framework of fish cages would use
weather-resistant and durable materials (e.g. HDPE cages, steel truss
cages). For other potential
circumstances (e.g. red tide event, outbreak of fish disease), the licensees
will review the need of fish raft relocation and propose the fish raft
relocation plan as necessary for agreement with AFCD on a case-by-case basis, depending
on the type of algal bloom (any toxicity to fish), expected duration of such
circumstances, feasibility for early harvesting of fish stock, feasibility of
implementing onsite control measures etc.
In case fish raft relocation is considered necessary, the fish rafts
will be relocated away from the areas of circumstances, avoid marine fairways
and utilities and at some distance away from ecological and fisheries sensitive
receivers (e.g. about 200 m away from established coral communities) to minimise
potential impacts to these sensitive receivers.
Such relocation will be temporary (e.g. a few weeks) and the fish rafts
will return to the Project site upon the cease of the circumstances. The mobilisation of the fish rafts will cause
temporary disturbance to marine habitat.
Increased operation of marine vessels will occur due to the towing of
fish rafts to the new location, and the re-anchoring of fish rafts will cause
temporary disturbance to the water column and seabed. The corresponding impacts would be similar to
those occurred in the construction phase (Section 4.5.1). Overall, impacts are
considered to be of minor significance and unacceptable impacts on marine
ecological resources are not expected.
Operation
of the fish farm would produce underwater sound from the management of fish
rafts / cages and fish stocks, and operation of marine vessels. The daily operations of mainly small marine
vessels, such as sampans or speed boats would be temporary which the underwater
sound characteristics of these vessels are similar to the operations at Wong
Wan FCZ and private mooring site nearby.
Marine organisms in these waters are habituated to the background level
of underwater sound, and a small increase in mariculture and vessel activities
associated with the operation of this Project are not anticipated to result in
unacceptable impacts on marine ecological resources and also marine habitats
within YCTMP which is located ~1.1 km away. HHWMP is considered to be far away (~2.7 km
from Project site) to be affected by the Project.
Mariculture activities would
result in an increase in water quality pollutants primarily
from fish feed, feed wastage, fish excretion and dead fish. The increase in pollution load would affect the water quality in the receiving waters and the potential impacts on marine ecological resources are as follows:
n
Suspended solids (SS)
dispersion;
n
Dissolved oxygen (DO)
depletion; and
n
Elevated nutrient levels.
To estimate the impacts on
marine ecological sensitive receivers of the Assessment Area, computer
modelling of changes in water
quality were conducted under two
scenarios:
n
Baseline scenario, which
covered the “without-project” condition in 2023; and
n
Project scenario, which took
into account the additional pollution load from the mariculture activities at
the Project site, as well as the other nearby proposed new fish culture zones
at Outer Tap Mun and Mirs Bay (each at their carrying capacity).
Relevant assessment criteria, i.e. Water Quality
Objectives (WQOs) in the Mirs Bay and Tolo Harbour and Channel WCZs, were then
used to assess potential impacts on marine ecological resources.
Fish farm operation are expected to generate SS within
the water column as a result of fish feed, fish feed wastage and fish
excretion, contributing to an increase in sediment deposition in close
proximity of the Project site.
The water quality modelling results have indicated
that at all marine ecological sensitive receivers, SS elevations as a result of
fish farm operation are predicted to be compliant with the relevant WQOs for
both wet and dry seasons. Impacts to
subtidal assemblages, such as fish, corals and benthic assemblages within and
in the vicinity of the Project site are expected to occur temporarily as the
modeling results indicate that the mariculture activities would only result in
short-term, localised elevations of SS.
The habitats affected are expected to be generally confined to the
Project site and subtidal assemblages in proximity to the Project site are
considered to be of low ecological value.
As the areas affected are predicted to have limited or no change of SS
levels between baseline and project scenarios, organisms are expected to be
exposed under similar environmental conditions as the fish farm operates. Based on the assumption that eventually the
affected areas will be recolonised by fauna typical of the area, the temporary
impact on these low ecological assemblages is not considered to be
unacceptable. Unacceptable impacts to
ecological assemblages, including species of conservation importance such as
amphioxus, marine mammals and horseshoe crabs, if present in the vicinity of
the Project site arising from elevated SS levels are not anticipated. Other marine ecological sensitive receivers
are predicted to be unaffected (as defined by the WQO and tolerance
criterion).
With the fish farm standing
stock kept within the Project site’s maximum carrying capacity and the use of
pellet feed within fish farms, potential impacts to marine ecological resources
will be well managed. The Project site
only occupies a very small proportion of the habitats and supported ecological
assemblages of low ecological value, whereas areas which supported marine
ecological resources of moderate to high values are recorded at YCTMP and HHWMP which are located at ~1.1 km away
and ~2.7 km away respectively from the Project site. Consequently, unacceptable impacts on marine
ecological resources are not expected to occur.
The relationships between SS and DO are complex, with
elevated SS in the water column together with a number of other factors to
reduce DO concentrations. Elevated SS
(and turbidity) reduces light penetration, lowers the rate of photosynthesis by
phytoplankton (i.e. primary productivity) and thus lowers the rate of oxygen
production in the water column.
Furthermore, the decomposition of organic matter in fish feed, fish
excretion and dead fish in the water column may consume DO in the receiving
waters. The resulting overall DO
depletion has the potential to cause an adverse effect on marine organisms,
especially to sessile organisms, such as corals, which cannot escape from the
hypoxia zone and could potentially cause mortality.
The water quality modelling results have indicated that DO
depletion associated with fish farm operation are predicted to be low and
remain compliant with the relevant WQO DO criteria at most marine ecological
sensitive receivers. Lower DO levels
recorded at the northern areas are likely a result of relatively high pollution
loading from dry weather load and treated sewage effluent from the Starling
Inlet (also known as Sha Tau Kok Hoi), as well as pollution load from Yantian
area of Guangdong. The predicted 10th-percentile
depth-averaged DO levels at the Project site are below the corresponding
assessment criterion. Such episodes of
low DO levels were also observed at Wong Wan FCZ in the past years without affecting the mariculture operation which are
typically driven by low bottom DO levels in summer months, and the situation at the Project site is worse than that
of the existing Wong Wan FCZ given the higher water depth. Mariculture operation at the Project site and
other proposed FCZs would result in some change in the mean and 10th-percentile
depth-averaged DO levels. In response to
lowered DO levels, mariculturists could consider providing aeration onsite to
improve DO levels at the fish farm by observing changes in fish behaviour due to
low DO levels, and real-time water quality monitoring device set up by AFCD
onsite will also help to detect signs of low DO levels and inform
mariculturists. Additional modelling
scenario has been conducted for the provision of aeration and results indicated
that aeration would be able to replenish DO levels consumed by mariculture
operation. Therefore, the predicted
reduction in DO levels at the Project site is expected to be controlled by
aeration as necessary and impacts from DO depletion due to fish farm operation
are considered to be of minor significance.
Overall, there is limited change in
the predicted DO levels at baseline and project scenarios, and unacceptable
impacts to marine ecological resources are not expected to occur.
High levels of nutrients released from fish feeds,
fish excretion and dead fish to the water column may potentially cause rapid
increases in phytoplankton population, on occasions to the point that an algal
bloom occurs. An intense bloom of algae can lead to sharp decreases
in the levels of DO. This decrease will initially occur in the
surface water, and then spread to deeper waters as dead algae fall through the
water column and decompose on the seabed. Anoxic conditions may
result if DO concentrations are already low or are not
replenished. This may result in mortality of marine organisms due to
oxygen deprivation.
The water quality modelling results have indicated
that the levels of nutrients as a result of fish farm operation are expected to
be low in general within the Assessment Area.
Predicted levels of Total Inorganic Nitrogen (TIN) and unionized ammonia
at the Project site and all marine ecological sensitive receivers are below the
assessment criterion. Overall, the
increased levels of nutrients in the water column as a result of fish farm
operation are considered to be of minor significance and unacceptable impacts
to marine ecological resources are not expected to occur.
Chlorophyll-a is a
photosynthetic pigment of phytoplankton and is commonly used as a direct
indicator of algal biomass. As mentioned
above, increased levels of phytoplankton due to nutrients released from fish
farms could potentially trigger algal blooms, in which could reduce DO levels
in the water column and result in mortality of marine organisms.
The water quality modelling
results have indicated that the levels of chlorophyll-a vary spatially across
the Assessment Area and are generally higher at the surface level and areas
with shallower water depth. There is no
change of predicted levels of chlorophyll-a at the Project site and the levels
are below the corresponding assessment criterion. All other marine ecological sensitive
receivers within the Assessment Area are also below the assessment
criterion. Therefore, fish farm
operation is not expected to result in significant increase of chlorophyll-a
and unacceptable impacts to marine ecological resources are not expected to
occur.
The new fish stocks to the Project site will have potential
risks in introducing invasive species to the marine environment if invasive
species are cultivated and escaped from the fish farms. Invasive species may result in increased
biological interactions (e.g. competition and predation) with native marine
species, and therefore may pose threats to the local marine biodiversity.
Regular
maintenance of fish farm equipment, typically the condition of fish cages and
fish nets would be performed by the fish farm owner, to minimise the potential
risk of fish escape to the nearby marine environment. Details of these operation measures and
practices are presented in Appendix 2A.
Upon implementation of these measures, unacceptable
impacts on the marine ecological resources are not anticipated.
Based upon the information
presented in Section 4.5, the significance of marine ecological impacts
associated with the construction and operation of the Project has been
evaluated in accordance with the EIAO-TM
(Annex 8, Table 1). The outcomes of this evaluation
are summarised in Table 4.12.
Table
4.12 Significance of Marine Ecological Impacts
Associated with the Construction and Operation of the Project Evaluated in
accordance with EIAO-TM
|
Potential
Impact |
Source |
Receiver |
Nature
of Impact |
Overall
Impact Significance |
Mitigation
/ Precautionary Measures Required |
|||||
|
Habitat
Quality |
Species
Affected |
Size
|
Duration |
Reversibility |
Magnitude |
|
|
|||
|
Construction phase |
||||||||||
|
Habitat
disturbance |
Construction of fish farm structures (including the production of noise, glare and dust). |
Marine waters and benthic habitats within and in the
vicinity of the Project site. |
Low to moderate |
Common fish species and benthic fauna dominated by polychaetes. Scarce amount of amphioxus (lancelet) Branchiostoma belcheri was recorded in wet season within the
Project site. |
All of the Project site (~35 ha). |
Temporary and short term (a few weeks) in the
active works area. |
Reversible |
Small |
Minor |
No |
|
Underwater sound |
Construction of fish farm structures and marine vessels. |
Marine
waters within and in the vicinity of the Project site. |
Low to moderate |
Common fish species and benthic fauna dominated by polychaetes. Scarce amount of amphioxus (lancelet) Branchiostoma belcheri was recorded in wet season within the
Project site. |
Localised to sound-generating activities,
e.g. assembly of fish rafts, installation of mooring system, marine vessels. |
Temporary and short-term (a few weeks) in the
active works area. |
Reversible |
Small |
Minor |
No |
|
YCTMP |
High |
Rare and common fish species. |
Localised to sound-generating activities, e.g.
assembly of fish rafts, installation of mooring system, marine vessels;
mostly affect area near the marine park boundary at Hung Shek Mun. |
Temporary and short term (a few weeks) in the
active works area |
Reversible |
Small |
Minor |
No |
||
|
Operation phase |
||||||||||
|
Changes in
marine habitat |
Fish farm operational activities (including the production of noise, glare and dust). |
Marine
waters and benthic habitat within and in the vicinity the Project site. |
Low to moderate |
Common fish species and benthic fauna dominated by polychaetes. Scarce amount of amphioxus (lancelet) Branchiostoma belcheri was recorded in wet season within the
Project site. |
Localised to the vicinity of fish farm structures (<35 ha). |
Long term over Project duration |
Reversible |
Small |
Minor |
No |
|
Temporary
relocation of fish rafts/ cages |
Fish farm |
Marine waters and benthic habitats within and in
the vicinity of the Project site. |
Low to moderate |
Common fish species and benthic fauna dominated by polychaetes. Scarce amount of amphioxus (lancelet) Branchiostoma belcheri was recorded in wet season within the
Project site. |
Localised to the immediate vicinity of the area
of fish rafts / cages relocation. |
Temporary |
Reversible |
Small |
Minor |
The licensees will review the need of fish raft
relocation and propose the fish raft relocation plan as necessary for
agreement with AFCD. |
|
Underwater sound |
Operational activities of fish farm and marine vessels |
Marine waters within and in the vicinity of the
Project site. |
Low to moderate |
Common fish species and benthic fauna dominated by polychaetes. Scarce amount of amphioxus (lancelet) Branchiostoma belcheri was recorded in wet season within the
Project site. |
Localised to the immediate vicinity of the
sound-generating activities e.g. maintenance of the fish cages and marine
vessel movement. |
Long term over Project duration but reversible. |
Reversible |
Small |
Minor |
No |
|
YCTMP |
High |
Rare and common fish species |
Localised to the immediate vicinity of the
sound-generating activities e.g. marine vessel movement; potential affect
areas near the marine park boundary at Hung Shek Mun. |
Long term over Project duration but reversible. |
Reversible |
Small |
Minor |
No |
||
|
Changes in water quality due to fish farm
operational activities |
Fish farm operational activities (e.g. fish feed,
fish drugs, waste water, etc.) |
Marine
waters, intertidal natural shores and benthic habitat within and in vicinity
of the Project site. |
Low to moderate |
Common fish species and benthic fauna dominated by polychaetes. Scarce amount of amphioxus (lancelet) Branchiostoma belcheri was recorded in wet season within the
Project site. |
Localised to the vicinity of the fish farm. |
Long-term over Project duration. |
Reversible |
Small |
Minor |
Water quality mitigation measures would further reduce impacts. |
|
YCTMP |
High |
Rare and common fish species and corals |
Localised to the vicinity of the fish farm; potentially affect areas near the marine park boundary at Hung Shek Mun. |
Long term over Project duration. |
Reversible |
Small |
Minor |
Water quality mitigation measures would further reduce impacts. |
||
|
Introduction of invasive species |
Fish stock in fish farm |
Marine waters within and in vicinity of the
Project site. |
Low to moderate |
Common fish species. |
Within and in the vicinity of Project site (~35 ha). |
Long-term over Project duration. |
Reversible but with difficulty |
Small |
Minor |
Operation measures and Practices in Appendix 2A would further
reduce impacts. |
|
YCTMP |
High |
Rare and common fish species. |
Within the YCTMP. |
Long-term over Project duration. |
Reversible but with difficulty |
Small |
Minor |
Operation measures and Practices in Appendix 2A would
further reduce impacts. |
||
As
there are no other existing or committed non-FCZ projects identified in the
vicinity of the Project site, the Water
Quality Impact Assessment conducted is based on the worst-case scenarios of
concurrent operation of all existing and planned FCZs as sources of
pollution. It is expected that all FCZs
will be operated within the maximum carrying capacity and therefore,
unacceptable impacts to water quality are not anticipated. Consequently, unacceptable cumulative impacts
to marine ecological resources are not predicted to occur.
As other marine organisms, including
marine mammals and horseshoe crabs are not found within and in the vicinity of
the Project site, potential cumulative impacts on these animals are not anticipated
and these impacts are expected to mainly affect fishes and benthic assemblages
if identified. Potential operational impacts
presented in Section 4.5.2 were examined to evaluate potential cumulative
impacts with other operations / developments in the northeastern Hong Kong
waters. Outcomes of this evaluation,
excluding the impact on water quality are summarised as follows:
n
Changes in Marine Habitat: In the northeastern waters,
the changes in marine habitat would
be approximately be 500 ha in total, including the Project site (35 ha), the
proposed Outer Tap Mun FCZ (55 ha) and the proposed Mirs Bay FCZ (410 ha). Although the area affected covers a certain
extent of Hong Kong waters, the provision of the proposed FCZs would support more mariculture operations
in Hong Kong and thus providing more fisheries resources to the local and
global fisheries market. Considering
that the marine
ecological resources in the northeastern waters where the Project site is
located are generally regarded as of low ecological value, the overall impacts
are minor, it is unlikely that the construction of the Project would exert an
unacceptable cumulative effect on the marine environment.
n
Underwater Sound: This Project is located ~1 km away from Wong Wan
FCZ and >3.5 km away from other existing and planned FCZs. The cumulative effect of underwater sound
will therefore consider the impact from the nearby Wong Wan FCZ only as other
FCZs are far away from the Project site.
For this Project, mainly small marine vessels e.g. sampans and speed
boats operated by fishermen would be used during FCZ operation. The underwater acoustic profiles generated by
works vessels of this Project would therefore be similar to the daily
operations of the nearby Wong Wan FCZ and private mooring site. Cumulative effects of works vessels
operational sound, if any, are anticipated to be negligible. It is not expected to result in significant
cumulative impact to the marine ecological resources within the Assessment
Area.
n Marine Traffic: This
Project is located at sufficient distance from other FCZs in the vicinity. It is expected to involve a relatively small
number of mainly small marine vessels, such as sampans and speed boats that
travel to and from the Project site during daily operations. Given that existing marine traffic is present
within Wong Chuk Kok Hoi near Wong Wan FCZ and the private mooring site, and
that the waters off northeastern Hong Kong have moderate levels of existing
marine traffic, such as the ferry route between Ma Liu Shui to Lai Chi Wo / Kat
O and Ma Liu Shui to Tap Mun, the cumulative effects of marine traffic
disturbance to the nearby marine ecological resources are anticipated to be
negligible.
Overall,
the cumulative impacts on marine ecological resources within the Assessment
Area are predicted to be minor and acceptable.
In accordance with the guidelines
in the EIAO-TM on marine ecology impact assessment, the general policy for
mitigating impacts to marine ecological resources, in order of priority, are:
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.
To summarise, this assessment of
impacts demonstrates that impacts will largely be avoided and minimised during
the construction and operation of the proposed Project, particularly to the key
marine ecological sensitive receivers, such as corals, mangroves, intertidal
habitats, ARs, nearby marine parks and SSSIs.
Impacts to marine ecological
resources and habitats have largely been avoided and minimised through proper
planning and design of the works. The
Project site is selected to be far from key marine ecological habitats, such as
key coral habitats around Wong Chuk Kok Tsui and Port Island, and mangroves and
ARs in YCTMP, such that impact to these habitats are avoided. The construction work of the FCZ is properly
designed such that no dredging work is required. To minimise the impacts to the vicinity of
the Project site, it is designed to have minimal construction work on
site. The scale of construction work
on-site is relatively small, and the number of vessels operating concurrently
are limited to a small number. The
installation time of fish farm structures is minimised and is expected to be
completed within a few weeks for each fish raft which would only cause
temporary disturbance to marine ecological habitat. Main components of the rafts / cages are
manufactured off-site and will be towed to the Project site using tug
boat. On-site assembly and anchoring of
the fish rafts / cages will be mainly assisted by a small number of marine
vessels such as sampans and small speed boats for up to a few trips per
day. No heavy construction plant would
be used. To minimise change of marine
habitat, the fish farm is designed to occupy minimal space which will only
occupy a thin surface layer (<0.5 m) within a small area. These measures are expected to control and
reduce potential impacts to marine ecological resources, and no marine
ecology-specific mitigation measures are thus required during construction.
The mitigation measures proposed to
mitigate water quality impact would also mitigate the potential impact to
marine ecological resources during construction and operation phase. Detail of the relevant mitigation measures
proposed are presented in Section 3.9.
Taking into consideration the impact
assessments in the previous sections and with effective implementation of the
proposed mitigation measures, the significance of residual impacts on marine
ecological sensitive receivers such as marine parks (Table 4.12) have been
evaluated in accordance with Annex
8 of the EIAO-TM. Residual impacts occurring as a result of the
proposed Project have been determined and are discussed as follows:
n
<35 ha of marine ecological
habitat will be affected during operation of the FCZ. While the design of fish
farm will only occupy a section of the water column and a small area of seabed,
with the small extent of affected habitat and the overall low marine ecological
value in the context of surrounding similar habitat, the impact due to the
change in marine habitat is considered to be of minor significance and
acceptable. Furthermore, with the implementation of the proposed mitigation
measures, the potential impact on marine ecological resources will be further
minimised. No unacceptable residual marine ecological impacts during the
construction and operation of the Project are therefore anticipated.
n
In addition, the fish farm
structures, which would provide artificial substrates for forming habitat and
shelter for juveniles or adult fisheries, would provide positive effects on
marine ecological resources within and adjacent to the Project Site.
Overall, the residual impacts of the Project would be
considered to be minor and acceptable.
As no unacceptable impacts
have been predicted to occur during the construction and operation of this
Project, monitoring of marine ecological resources during these project phases
is not considered necessary.
A review of baseline information on
marine ecological resources surrounding the waters of the proposed Project from
available literatures and field surveys has been undertaken, covering the
intertidal, subtidal soft bottom and hard bottom habitats, and marine waters. Results of the review and field surveys
indicated that marine ecological resources in the vicinity to the Project site
are generally regarded as of low ecological value (apart from very low
abundance of amphioxus (lancelet), Branchiostoma
belcheri, identified within the Project
site during wet season), whereas further afield habitats and sensitive
receivers of ecological values, including the artificial reefs and corals
within existing marine parks (i.e. YCTMP and HHWMP) are located at some
distances from the Project site.
Species of conservation importance such as horseshoe crabs and Marine
Eel Grass are found to be located out of the Assessment Area, and no records of
marine mammals in the Assessment Area have been reported.
During the construction of the
Project, direct impacts arising from the proposed marine works include
disturbance to the marine habitat (i.e. ~35 ha, including the water column and
a small area of seabed confined to a thin surface
layer (<0.5 m)). Considering
the temporary nature of the disturbance and the overall low ecological value of
marine ecological resources at and in the vicinity of the Project site,
unacceptable impacts on marine ecological resources are not expected. Impact of elevated levels of underwater sound
as a result of construction activities are considered acceptable with the
presence of existing underwater sound from the nearby Wong Wan FCZ and private
mooring site. No marine
ecological-specific mitigation measures are required during construction.
During FCZ operation, there will be
changes in marine habitat at the location of fish farm structures (<35
ha). The structures mainly occupy a
section of the water column and a small area of seabed confined to a thin surface layer (<0.5 m). The presence of fish farm structures will also
provide hard substrates that could be colonised by a variety of marine
organisms and bringing potential positive effect on marine ecological
resources. Considering the relatively
small area affected in the context of surrounding similar habitat and the
overall low marine ecological importance at and in the vicinity of the Project
site, unacceptable impacts on marine ecological resources are not
expected. Potential impacts of elevated
levels of underwater sound generated from the marine vessels in the vicinity of
the Project site are considered acceptable with the presence of existing
underwater sound from the nearby Wong Wan FCZ and private mooring site. Temporary relocation of fish rafts due to
potential circumstances may occur over a short time, therefore, unacceptable
impacts are not anticipated. Impacts of
changes in water quality arising from FCZ operation are predicted to be largely
confined in the vicinity of the Project site within the maximum carrying capacity. The predicted reduction in DO levels at the
Project site is expected to be controlled by aeration as necessary and impacts
from DO depletion due to fish farm operation are considered to be of minor
significance. Impact on the introduction
of invasive species would be considered minor with regular monitoring of
mariculture facilities. No marine
ecology-specific mitigation measures are required during operation.
Overall, no unacceptable impacts to marine ecological resources and species of
conservation importance are expected to occur.
All of the potential construction and operational marine ecological
impacts identified are deemed acceptable.
([2]) The
Legislative Council Commission (2021) LEGISLATIVE COUNCIL BRIEF Country Parks
Ordinance (Chapter 208) DOUBLE HAVEN AND OTHERS (SPECIAL AREAS) ORDER 2010.
([9]) Goodkin
NF, Switzer AD, McCorry D, DeVantier L, True JD, Hughen KA, Angeline N, Yang TT
(2011) Coral communities of Hong Kong: long-lived corals in a marginal reef
environment. Marine Ecology Progress Series. 426:185-196.
([10]) ERM
(2003) The Proposed Submarine Gas Pipeline From Cheng Tou Jiao Liquefied Natural
Gas Receiving Terminal, Shenzhen to Tai Po Gas Production Plant, Hong Kong. EIA
Study (EIA-089/2003). Prepared for The Hong Kong and China Gas Company Limited.