|
Consultancy Ref.:
AFCD/FIS/02/19 Consultancy Service for Environmental Impact Assessment Study
for Designation of New Fish Culture Zones Environmental Impact
Assessment (EIA) Report for Establishment of Fish Culture Zone at Po Toi
(Southeast)
November 2022
|
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);
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
Southern Water Control Zone (WCZ).
Detailed description of the physical characteristics of the marine
environment of the Assessment Area and compliance of WQOs is provided in the 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
reserve, coral communities, intertidal habitat, marine benthos of conservation
interest, and marine ecological important species including Finless Porpoises
(FPs) and amphioxus. 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 Po Toi (Southeast) 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: 30 Sep 2020, 22 Oct 2020, 30 Oct
2020 Dry Season: 15 Jan 2021, 6 Feb
2021 |
|
Coral Survey |
20 Nov 2020 |
|
Drop Camera Survey |
27 Dec 2020 |
A total of 157 individual organisms were collected from the seven
grab samples from Po Toi during the wet season survey (Figure B2.3
of Appendix 4B). The specimens belong to 7 Phyla with a total of 8 classes, 26 families and 36 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 in general
comparing to dry season (Table 4.2
and
Table 4.3). In terms of infaunal abundance, the majority
(~73%) of organisms recorded were from the Phylum Annelida. The polychaete worms, Aglaophamus dibranchis and Prionospio
ehlersi were the most abundant species from the wet season survey (total
abundance of both species = 29 individuals).
No species of conservation interest was recorded in the survey. In terms of infaunal biomass, organisms from
the Phylum Chordata contributed ~66% of the total biomass recorded, while
organisms from Annelida and Arthropoda also contributed significant biomasses
(~17% and ~11% respectively). The high
biomass of Chordata was contributed by two fish species, Odontamblyopus rubicundus and Paratrypauchen
microcephalus which are not species of conservation interest.
A total of 329 individual organisms were collected from the seven
grab samples during the dry season survey.
The specimens belong to 7 Phyla
with a total of 10 classes, 43
families and 58 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
(~60%) of
organisms recorded were from the Phylum Annelida and Nemertea (~16%).
Ribbon worm (Phylum: Nemertea) was
the most abundant species from the dry season survey (total abundance = 51 individuals). No species of conservation interest were
recorded in the survey. In terms of
infaunal biomass, organisms from the Phylum Mollusca contributed ~52% of the total biomass recorded,
while organisms from Chordata also contributed significant biomasses
(~30%). The high biomass of Mollusca was contributed by a number of species, primarily by a bivalve
species, Corbula erythrodon.
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) |
Shannon Diversity (H’) |
Total Biomass (g wet weight) |
Mean Biomass per Individual (g wet weight) |
|
PT1 |
22 |
229.17 |
10 |
13 |
0.90 |
2.30 |
0.2583 |
0.0117 |
|
PT2 |
28 |
291.67 |
16 |
17 |
0.94 |
2.66 |
0.5850 |
0.0209 |
|
PT3 |
20 |
208.33 |
8 |
9 |
0.85 |
1.86 |
0.0930 |
0.0047 |
|
PT4 |
18 |
187.50 |
7 |
7 |
0.76 |
1.48 |
2.5160 |
0.1398 |
|
PT5 |
15 |
156.25 |
10 |
11 |
0.96 |
2.30 |
0.4144 |
0.0276 |
|
PT6 |
19 |
197.92 |
8 |
10 |
0.88 |
2.03 |
0.1763 |
0.0093 |
|
PT7 |
35 |
364.58 |
14 |
15 |
0.90 |
2.45 |
0.3430 |
0.0098 |
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) |
|
PT1 |
43 |
447.92 |
19 |
20 |
0.91 |
2.71 |
0.1808 |
0.0042 |
|
PT2 |
34 |
354.17 |
13 |
14 |
0.92 |
2.43 |
0.0507 |
0.0015 |
|
PT3 |
94 |
979.17 |
29 |
34 |
0.90 |
3.18 |
0.7949 |
0.0085 |
|
PT4 |
61 |
635.42 |
19 |
25 |
0.91 |
2.93 |
2.2264 |
0.0365 |
|
PT5 |
24 |
250.00 |
14 |
18 |
0.97 |
2.81 |
0.7641 |
0.0318 |
|
PT6 |
52 |
541.67 |
19 |
24 |
0.93 |
2.96 |
0.4212 |
0.0081 |
|
PT7 |
21 |
218.75 |
10 |
11 |
0.94 |
2.27 |
4.8297 |
0.2300 |
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 -7 mCD |
The seabed was mainly composed of bedrock in both shallow water (-3 to
-4 mCD) and deep water (-5 to -7 mCD).
Sparse hard coral colonies, such as Tubastrea / Dendrophyllia sp.
and Balanophillia sp. were
identified in deep water. Sparse octocorals,
such as Echinomuricea sp. were
recorded in deep water. |
|
T2 |
-3 to -7 mCD |
The site mainly composed of bedrock in both shallow water (-3 to -4
mCD) and deep water (-5 to -7 mCD).
Hard coral colonies, such as Tubastrea
/ Dendrophyllia sp., were identified
to be common in shallow
and in deeper water. Sparse
octocorals, such as Echinomuricea
sp. were recorded in deep water. |
Transects
are located at southeast natural shores of Po Toi (T1 and T2) (Figure
B2.1 of Appendix
4B). The site mainly comprised of bedrock (51% -
75%). Colonies of hard coral were
sparsely to commonly distributed (<5% - 30%), and octocorals were sparely
distributed (<5%) in deeper water. Macroalgae (<5%) and other benthos (11
– 30 %), such as, sea anemones, zoanthids and sponges were also identified (Table
4C.3 of Appendix
4C).
A total of thirteen hard corals species, ten octocorals species, three species of sea
anemones, one zoanthid, one sponges, two algae species and one ascidian species
were identified (Table
4C.4 of Appendix
4C). The majority of corals recorded were common and
widespread species in Hong Kong.
Ahermatypic hard coral Tubastrea /
Dendrophyllia sp. were common at both shallow and deep area at transect
T2. Encrusting sponge was common at deep
water of transect T1 and at shallow area of transects T1 and T2. Other corals and benthos were generally
present in isolated colonies. 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 relatively low to moderate sessile taxa.
Common and widespread hard corals were recorded in low to moderate percentage cover (<5% - 30%) in
general, with octocorals recorded at deeper waters.
Drop camera surveys were
conducted at southeast of Po Toi at the survey locations shown in Figure B2.1 of Appendix 4B. A total of seven 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 (~-30 mCD) was consisted of silty mud without any hard substrate
and benthic organisms recorded.
Representative photos 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 Marine Reserve,
and Site of Special Scientific Interest (SSSI). No designated Country Park and Special Area
are located within the Assessment Area.
Some of these that are relevant to marine ecology and are located in the
Assessment Area are discussed below.
Cape D’ Aguilar Marine Reserve
(CDMR) is the marine reserve within the Assessment Area. No other existing or proposed marine reserves
or marine parks are identified within the Assessment Area. Details of the marine reserve are provided in
Table
4A.2.1 of Appendix 4A.
The location of the marine reserve is provided in Figure 4A.2.1 of Appendix 4A ([1]).
Sites
of special scientific interest in the Assessment Area include Hok Tsui (Cape D'Aguilar) Site of Special
Scientific Interest (SSSI). Hok Tsui
(Cape D'Aguilar) is located at ~4 km away from the Project site which is considered
to be too far to be affected by the Project. Details
of the SSSI are provided in Table 4A.2.1 of Appendix 4A.
The location of Hok
Tsui (Cape D'Aguilar) SSSI is provided in Figure
4A.2.1 of Appendix 4A ([2]).
Finless Porpoises (FPs) are mainly distributed in the southern and
eastern waters of Hong Kong, while Chinese White Dolphins (CWDs) are mainly
distributed in western and southwestern waters of Hong Kong. As the Project site lies within southern Hong
Kong waters, the following discussion will mainly focus on FPs. With reference to the AFCD Marine Mammal Monitoring Report
results during 2012-2021 ([3]),
it was reported that porpoise densities were low to moderate around the Po Toi Islands (i.e. Po
Toi, Beaufort Island, Sung Kong and Waglan Island), in the offshore waters in
Po Toi survey area, as well as at the juncture of the Po Toi and Ninepins
survey areas in the wet seasons
(June through November). The porpoise densities at the Project site were low compared
to offshore waters (Figure 4A.2.4 of Appendix 4A). The encounter rate of FP varied over time
between 2004-2021 and the FP encounter rate at Po Toi waters was slightly
lowered in recent years (2017-2020) (Figure 4A.2.5 of Appendix 4A). During 2021, higher density (DPSE
values) of FP was recorded at some locations in the Assessment Area, including
southern waters of Po Toi. However, it
should be noted that the survey effort in Po Toi were considered to be relatively
low and could cause bias. Regardless,
the survey results from AFCD consistently indicate that FP utilises the waters
in the Assessment Area in the recent years but mainly in the summer and autumn
months. The encounter rate and seasonal
distribution of FPs remain to be similar in recent years and it is considered
that the data from the long-term marine mammal monitoring conducted by AFCD are
comprehensive and adequate for this Project.
No further baseline survey for marine mammals would be necessary.
No mangrove stands were found
within the Assessment Area and at the Project site. Species of conservation interest associated
with the habitat such as horseshoe crab is not present and the impact of the
Project on mangroves and horseshoe crab is therefore not anticipated.
Coral communities in the southern waters of Hong Kong generally have a
lower diversity and abundance due to the influence of Pearl River outflow ([4])
compared to the eastern
waters of Hong Kong with higher salinity and lower turbidity ([5]). In
the southeastern and southern parts of Hong Kong, stony corals generally form
small and isolated colonies on hard bottom substrates. Both coral coverage and species diversity are
found to be low. A recent study
suggested that the southern Hong Kong waters, including Waglan Island and Cape
D’Aguilar, featured low coral cover and low generic richness of small
encrusting colonies when comparing to northeastern, southeastern and eastern
coastal waters ([6]).
Unlike the
hermatypic hard corals, ahermatypic octocorals (including gorgonians, soft
corals and black corals) which many of them do not require light for
zooxanthellae photosynthesis, are more widely distributed in southern waters
and often occur at greater depths. Literatures revealed that hard corals in the areas around Po Toi have a
coverage of generally less than 10% and <5% recorded near Po Toi (Southeast)
region. No Reef Check
surveys were conducted at or near the Project site during 2016-2020. Coral communities with higher ecological value were recorded at Po Toi
(northeast), Beaufort Island (east to southeast), Sung Kong (northwest) and
Waglan Island (southwest and southeast) which are located at >0.3km, 3 km,
2.4 km and 1.1 km from the Project site respectively. Indicative locations of the coral
communities with higher ecological value are provided in Figure 4A.2.1 of Appendix 4A
([7]) ([8]) ([9]) ([10]).
Results of the Feasibility Study of this Project has revealed that a total of 25
species of hard corals, 10 species of octocorals and 2 species of black corals
were found in southeastern shore of Po Toi.
The coral colonies in this region composed of sparse (<5% coverage)
and low diversity of hard corals and octocorals. The species recorded are generally common and
widespread, including ahermatypic hard corals Tubastrea / Dendrophyllia sp.,
hermatypic hard corals Plesiastrea versipora and Porites sp. and
octocorals Dendronephthya sp. and Echinomuricea sp.. Coral communities of high ecological concern were
not identified within and in the vicinity of the Project site. High coverage of octocorals and black corals
(51-75%) were found mainly in deep waters of Lo Chau Mun (Southeast of Beaufort
Island).
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.
Ahermatypic hard corals Tubastrea / Dendrophyllia sp. were
common at both shallow and deep areas while other corals and benthos were
generally present in isolated colonies.
Overall, the surveyed areas showed low to moderate percentage coral coverage (<5% - 30 %) and low to moderate sessile taxa coverage on the subtidal
hard substrate. Results of drop camera survey showed
that the seabed of this site
(~-30 mCD) was dominated of 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, it was reported that were no findings of amphioxus within the Project site.
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.
Studies showed that benthic communities in the southern waters are
generally dominated by common and widespread species without any species of
concern identified, such as seagrass species.
Therefore, impact of the Project on the subtidal assemblages is not anticipated.
Breeding behaviour of white-bellied sea eagle (WBSE)
was recorded in 4-6 years in the Sung Kong nesting ground from 2002 to 2020
within the Assessment Area, which the nesting ground is located > 1 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. Compared
with the rest of the nesting sites found in Hong Kong by the AFCD survey, the
usage of the nesting site as breeding ground is relatively low and the majority
of nesting sites with more than 10 years of recorded breeding behaviour are
mainly located at Sai Kung east like Tsim Chau and in Port Shelter. With the relatively low usage of nesting
grounds of WBSE in the vicinity of the Project site, the impact of the Project on the WBSE is therefore not anticipated. Location
of the WBSE nesting grounds is 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 Area (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 Table 4.5 to Table 4.9.
Table 4.5 Marine Ecological Importance of Existing Marine
Reserve and SSSI within the Assessment Area
|
Criteria |
Cape
D' Aguilar Marine Reserve and Cape D' Aguilar SSSI |
|
Naturalness |
Natural intertidal and subtidal hard and
soft bottom habitat and marine waters |
|
Size |
~31.5 ha |
|
Diversity |
High |
|
Rarity |
Exhibits a high diversity of habitats in a small
area which is uncommon in Hong Kong waters.
Habitats harbor various marine organisms, including different corals,
such as, ahermatypic hard corals, hermatypic corals, soft corals, etc. |
|
Re-creatability |
Not re-creatable |
|
Fragmentation |
Unfragmented |
|
Ecological Linkage |
Linked to the intertidal and subtidal
habitats |
|
Potential Value |
Already designated as marine reserve |
|
Nursery / Breeding Area |
No significant records identified |
|
Age |
Designated as marine reserve in July 1996
and SSSI in July 1990 |
|
Abundance |
High abundance of hard coral has been
recorded at the site |
|
Ecological
Importance |
High |
Table
4.6 Ecological Importance of Intertidal Habitats within and in the vicinity of the
Project site
|
Criteria |
Hard Bottom Intertidal Habitat |
|
Naturalness |
Natural habitat |
|
Size |
Large, majority of the shoreline within and in the vicinity of the Project site |
|
Diversity |
High |
|
Rarity |
Intertidal organisms recorded at site such as seasnail, Diodora cruciata and red algae, Hildenbrandia rubra are generally
considered as widespread and common in Hong Kong |
|
Re-creatability |
Not re-creatable |
|
Fragmentation |
Unfragmented |
|
Ecological Linkage |
Not functionally linked to any high value habitat in a significant way |
|
Potential Value |
Unlikely to become an area of conservation value |
|
Nursery / Breeding Area |
No significant records identified |
|
Age |
N/A |
|
Abundance |
Low abundance |
|
Ecological
Importance |
Low |
Table
4.7 Ecological Importance of Subtidal Hard-Bottom
Habitats within and in the vicinity of the Project site
|
Criteria |
Po Toi
(Southeast) |
Lo Chau
Mun (Beaufort Island Southeast) |
Sung Kong Island (Northwest) |
Waglan Island |
|
Naturalness |
Natural |
Natural |
Natural |
Natural |
|
Size |
Large. The natural rocky shore
of Po Toi is about 11 km in length |
Large. The natural rocky shore southeast to
Beaufort Island is about 700 m in length |
Small. The natural rocky shore at Sung Kong Island
Northwest is about 150 m in length |
Moderate. The natural
rocky shore at Waglan Island South is about 2 km in length |
|
Diversity |
Low to Moderate |
Low to moderate |
Low to moderate |
Low to moderate |
|
Rarity |
Assemblages comprise typical
common and widespread hard corals and
octocorals species in Hong Kong, including ahermatypic hard coral Tubastrea / Dendrophyllia sp.,
hermatypic hard coral Plesiastrea versipora and Porites sp. and
octocoral Dendronephthya sp. and Echinomuricea sp |
Assemblages mainly comprise typical
common hard corals and octocorals species in Hong Kong, including
ahermatypic hard coral Tubastrea / Dendrophyllia sp., hermatypic hard
coral Plesiastrea versipora and
Cyphastrea serailia and octocoral Dendronephthya sp. and
Echinomuricea sp |
Assemblages are considered to mainly
comprise typical common and widespread species in Hong Kong. No rare species is recorded at the site |
Assemblages are considered to mainly
comprise typical common and widespread species in Hong Kong. No rare species is recorded at the site |
|
Re-creatability |
Not re-creatable |
Not re-creatable |
Not re-creatable |
Not re-creatable |
|
Fragmentation |
Unfragmented |
Unfragmented |
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 |
Not functionally linked to any
high value habitat in a significant way |
|
Potential Value |
Habitat is relatively
undisturbed which might exhibit some potential value |
Moderate-high coverage of
octocorals and black corals were recorded at the deeper water of the site
which exhibit higher ecological value |
Habitat is relatively undisturbed
which might exhibit some potential value |
Habitat is relatively undisturbed
which might exhibit some potential value |
|
Nursery / Breeding Area |
No significant records
identified |
No significant records
identified |
No significant records
identified |
No significant records
identified |
|
Age |
N/A |
N/A |
N/A |
N/A |
|
Abundance |
Low coverage of coral is present |
Moderate to high coverage of
octocoral and black coral is present |
Low to moderate coverage of coral is
present |
Low to moderate coverage of coral is
present |
|
Ecological
Importance |
Low |
Moderate to
High |
Low to Moderate |
Low to Moderate |
Table
4.8 Ecological Importance of Subtidal Soft Benthos
Assemblages within the Project site
|
Criteria |
Po Toi
(Southeast) |
|
Naturalness |
Natural |
|
Size |
~100 ha |
|
Diversity |
Low |
|
Rarity |
The assemblages are typical of similar habitats in the Hong Kong
waters, which are dominated by polychaetes.
No rare species has been recorded in the subtidal soft bottom habitat
in this area |
|
Re-creatability |
Re-creatable; substrata may be recolonised by benthic organisms |
|
Fragmentation |
Unfragmented. |
|
Ecological
Linkage |
Not functionally linked to any high value habitat in a significant
way |
|
Potential
Value |
It is unlikely that the habitat could develop conservation importance |
|
Nursery
/ Breeding Area |
No significant records identified |
|
Age |
N/A |
|
Abundance |
The assemblages are of low to moderate abundance and biomass |
|
Ecological Importance |
Low |
Table
4.9 Ecological Importance of Marine Waters within
the Project site
|
Criteria |
Waters in Po Toi and in the vicinity |
|
Naturalness |
Natural |
|
Size |
Waters around Po Toi, Beaufort Island, Sung Kong and Waglan |
|
Diversity |
Mainly FPs in the vicinity of the Project site |
|
Rarity |
FP is a resident species in Hong Kong. Commonly observed in southern
waters of Hong Kong |
|
Re-creatability |
Not re-creatable |
|
Fragmentation |
Unfragmented |
|
Ecological Linkage |
Linked to FP and marine habitat nearby |
|
Potential Value |
Potential habitat to develop conservation importance |
|
Nursery / Breeding Area |
Potential nursery and breeding area for FPs |
|
Age |
N/A |
|
Abundance |
The Project site is located within the potential habitats of FP. |
|
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 Coral (>20 spp.) |
Acropora solitaryensis,
Goniopora
lobata, Porites sp., Duncanopsammia peltata, etc. |
Protection
of Endangered Species of Animals and Plants Ordinance (Cap.586) |
Majority being common and widely
distributed in the eastern waters of Hong Kong with some uncommon species |
ü |
ü |
In the vicinity of the Project
site and throughout southeastern waters of Hong Kong |
|
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 waters |
ü |
ü |
In the vicinity of the Project
site and throughout southeastern waters of Hong Kong |
|
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 |
ü |
ü |
In the vicinity of the Project
site and throughout southeastern waters of Hong Kong |
|
Black Coral |
Antipathes curvata, Cirripathes
sinensis, 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 |
|
Two species
are recorded in the vicinity of the Project site. Generally present at greater depths in the
northeastern and southeastern waters of Hong Kong e.g. Lo Chau Mun, 3 km away from the Project site |
|
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 |
|
Sung Kong Island, 1.1 km away
from the Project site |
|
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 |
ü |
|
In the vicinity of the Project
site, and throughout eastern and southeastern waters of Hong Kong |
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 |
Sung Kong Island
|
1.9 |
|
Waglan Island |
2.3 |
|
|
Po Toi |
0.3 |
|
|
Lo Chau Mun (Southeast
of Beaufort Island) |
2.3 |
|
|
Designated
Marine Reserve |
Hok
Tsui (Cape D’Aguilar Marine Reserve) |
4.0 |
|
Designated
SSSI |
Hok
Tsui (Cape D’Aguilar SSSI) |
4.0 |
The Method Statement on Marine Ecological
Impact Assessment for Po Toi (Southeast) 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 work 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 100 ha and a small area of benthic habitat. 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 CDMR which is located far away (~4 km from Project site), 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. Species of conservation
importance, such as amphioxus was not recorded within the Project site. The overall coral coverage within and in the
vicinity of the Project site is considered to be low to moderate coral coverage (<5% - 30 %)
with mostly common and widespread species. Other species recorded are considered to
occur frequently in Hong Kong. Overall,
the subtidal habitat within the Project site was considered as of low
ecological importance. FPs usage of marine
waters around Po Toi and Southern waters of Hong Kong were shown to be moderate
and no recorded sightings were found within the Project site. Considering
that the area affected represents only a small portion of the available habitat
for the FPs and a minor portion of an individual animal’s movement range, and
only a small number of marine vessels will be present within and in the
vicinity of the Project site during the construction phase, the potential risk
of vessel collision with FPs is also not expected.
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, the
disturbance would represent a small fraction of the widely available
habitat. The 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 organisms, such as fish species and marine
mammals, 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 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. Dredging and
other noise-intensive construction activities are absent from this Project,
therefore underwater sound generated from construction activities is not
expected to produce pulsed high-energy sound sources that would affect the
hearing and echolocation ability of marine mammals within and in the vicinity
of the Project site.
Waters within the Assessment Area
and its vicinity is subject to high levels of marine traffic by similar types
of vessels. It is reasonable to assume
that marine organisms, are habituated to high 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
<100 ha. The relatively small extent of area affected compared to similar
habitats within the Assessment Area which is of overall low ecological
importance, impacts are considered to be of minor significance and unacceptable
impacts on marine ecological resources are not expected. The area affected also represents only a
small portion of the available habitat for the FPs and a minor portion of an
individual animal’s movement range, and only a small number of marine vessels
will be present within and in the vicinity of the Project site during the
operation phase, the potential risk of vessel collision with FPs is therefore
not anticipated, unacceptable impacts on marine mammals due to the Project 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 the
creation of artificial habitat may also include an increase of biological
productivity and 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 organisms, such as fish species and marine
mammals, 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 the marine
organisms, such as fish species and marine mammals. 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 Po Toi FCZ
and marine traffic at ferry routes near Po Toi pier. Marine organisms, such as fish species and
marine mammals 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 CDMR which is located far away (~4 km from Project site).
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.
Relevant assessment criteria, i.e. Water Quality
Objectives (WQOs) in the Southern WCZ, was 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, there are no notable changes
for the predicted SS levels between baseline and project scenarios, which are
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 temporary 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. Changes in SS levels also do
not appear to have a direct impact on marine mammals since these animals are
air breathing and have evolved to inhabit areas
near river mouths and estuarine-influenced coastal waters with high
turbidity. Unacceptable impacts to
ecological assemblages, including species of conservation importance such as
marine mammals and amphioxus, if present in the vicinity of the Project site
arising from elevated SS levels are therefore not anticipated. Other marine ecological sensitive receivers
are predicted to be unaffected (as defined by the WQO and tolerance
criterion).
With the fish farm production scale kept within the
Project site’s maximum carrying capacity and the use of pellet feed within fish
farms, potential impacts to marine ecological assemblages will be well
managed. The Project site only occupies
a small proportion of the habitats and supported ecological assemblages of low
ecological value. Areas which supported
marine ecological resources of moderate to high values are recorded at CDMR
which is located far away at ~4 km from the Project site. As such, unacceptable impacts from fish farm
operation on marine ecological resources, due to potential elevations of SS 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. Depletion of DO, however, do
not appear to have a direct impact on marine mammals since these animals are
air breathing and have evolved to inhabit areas
near river mouths and estuarine-influenced coastal waters with high
turbidity.
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 all marine ecological
sensitive receivers for both wet and dry seasons. The predicted 10th-percentile
depth-averaged DO level at the Project site is above the corresponding
assessment criterion. The comparison
between the baseline and project scenarios shows that the
mariculture operation at the Project site would result in no notable change in
DO level and the predicted changes in DO levels were even lower or
undetectable at other marine ecological sensitive receivers.
Overall, there is limited change in
the predicted DO levels under with project scenario,
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 decrease
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 such
as corals, which cannot escape from the hypoxia zone. Decreased oxygen content, however, do
not appear to have a direct impact on marine mammals since these animals are
air breathing and have evolved to inhabit areas
near river mouths and estuarine-influenced coastal waters with high turbidity.
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 unionized ammonia at the Project site and all marine
ecological sensitive receivers are below the corresponding assessment
criterion, except for Total Inorganic Nitrogen (TIN). The predicted levels of TIN were higher than
the corresponding assessment criterion at the Project site and all WSRs under
baseline and project scenarios, as a result of relatively high background
levels for TIN levels in the Southern WCZ.
There was slight increase of predicted TIN levels at the Project site
and the adjoining waters which are located within Finless
Porpoise habitats in southern waters. Given such areas of TIN elevation are
considered very small (<1% when comparing to the available Finless
Porpoise habitats in Hong Kong waters), unacceptable
impact to the Finless Porpoise habitat due to the Project is not
anticipated. In addition, the corals at
southeastern side of Po Toi Island are also expected to experience the slight
increase of predicted TIN levels under the Project. Literatures suggested that
the corals in Hong Kong have adapted to eutrophic condition with higher
nitrogen concentrations ([13])([14])
and thus such slight increase in TIN levels is not expected to adversely
affect the corals. According to historical
records, minor increase of TIN levels of up to 0.2 mg/L were occasionally
recorded at Po Toi FCZ, which is similar to the predicted levels under both the
baseline and project scenarios and yet there was no adverse impact from Po Toi
FCZ to the marine ecological sensitive receivers in the vicinity. Mariculture in Hong Kong has previously been
operated under waters with elevated TIN levels and associated risks, such as
algal blooms are some well-known risks that have been accustomed by
mariculturists. Preventative measures,
such as real-time water quality monitoring at existing FCZs and notification of
heightened risk of algal bloom to mariculturists have been adopted by AFCD.
With the historical record of elevated TIN in Southern
WCZ and also preventative measures to be adopted, 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 such as corals, which cannot escape from the hypoxia zone. Decreased oxygen content, however, do not
appear to have a direct impact on marine mammals since these animals are air
breathing and have evolved to inhabit areas near river mouths and
estuarine-influenced coastal waters with high turbidity.
The water
quality modelling results have indicated that the levels of chlorophyll-a were
generally low across the Assessment Area, which were generally higher at the
surface levels and at areas with shallower water depth. There is no change of the 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 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 |
Common fish species and benthic fauna dominated by polychaetes and
ribbon worms. |
All of the Project site (~100 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 |
Common fish species and benthic fauna dominated by polychaetes and
ribbon worms. |
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 |
|
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 of the Project site. |
Low |
Common fish species and benthic fauna dominated by polychaetes and
ribbon worms. |
Localised to the vicinity of fish farm structures (<100 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 |
Common fish species and benthic fauna dominated by polychaetes. |
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 |
Common fish species and benthic fauna dominated by polychaetes and
ribbon worms. |
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 |
|
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 |
Common fish species and benthic fauna dominated by polychaetes and
ribbon worms. |
Localised to the vicinity of the fish farm. |
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 |
Common fish species. |
Within and in the vicinity of Project site (~100 ha). |
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 amphioxus and horseshoe crabs were not found
within and in the vicinity of the Project site and WBSE nesting ground is found
only to be of low usage at Sung Kong, potential cumulative impacts on these
animals are not anticipated and these impacts are expected to mainly affect
marine mammals, 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 southern Hong Kong
waters. Outcomes of this evaluation,
excluding the impact on water quality are summarised as follows:
n
Changes in Marine Habitat: Since no other FCZ is currently
proposed in the southeastern waters, the changes in habitat would
approximately be 100 ha in total.
Although the area affected covers a certain extent of Hong Kong waters, the provision of the proposed FCZ 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 southeastern 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 at 2.3 km away from the existing Po Toi FCZ
and the cumulative effect of underwater
sound will therefore consider the impact from the nearby Po Toi FCZ only. 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 Po Toi FCZ. 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 sufficient distance from the existing Po Toi
FCZ.
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 at the southern waters of Hong Kong with
high levels of marine traffic within and in the vicinity of the Project site,
the cumulative effects of marine traffic disturbance to the 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, intertidal habitats,
nearby marine reserve 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 Lo Chau Mun (southeast of Beaufort Island) and CDMR,
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 (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
<100 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
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
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.
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 values, whereas sensitive receivers
of ecological values such as corals located at Lo Chau Mun (southeast of
Beaufort Island) and existing marine reserve, CDMR are at a distance from the
Project site. Species of
conservation importance such as Finless Porpoises are
found to have moderate abundance in the vicinity of the Project site and within
the Assessment Area. Records of
White-Bellied Sea Eagle nesting site was also found on Sung Kong but with relatively low
usage. Other species of concern
including amphioxus and horseshoe crabs are not found within the Assessment
Area.
During the construction of the Project, direct impacts
arising from the proposed marine works include disturbance to the marine
habitat (i.e. ~100 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, such as fish species and marine mammals, 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 nearby Po Toi
FCZ and Po Toi pier. 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 (<100
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, such as fish species
and marine mammals, 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 high level of
marine vessel operations near waters of Po Toi.
The 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. Considering
the historical record of elevated TIN levels in Southern WCZ and also
preventative measures to be adopted at the Project site, the impact due to the
predicted increase of TIN levels at the Project site only is expected to be of
minor significance. Impact on the
introduction of invasive species would be considered minor with regular
monitoring of mariculture facilities. No
marine ecological-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.
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