The waters and coastal areas of Southwest
Lantau including the Soko Island group, which are located away from the major population
centres of Hong Kong, have long been the subject of interest by academics,
government and green groups, and there is a broad consensus that this general
area is an area of conservation interest including from a marine ecological
perspective. A variety of studies
have investigated the marine ecology of Southwest Lantau waters , and as a
result of these and in particular the AFCD-commissioned feasibility study ([1]),
both the coastal waters off Southwest Lantau Island and the waters around the Soko
Island Group have been proposed for designation as Marine Parks.
This Annex
presents the findings of marine ecological studies of the
9.1.1
Ecological Study Area
The Study Area for the ecological
assessments is based on the footprint of the proposed LNG terminal on
The South Soko LNG terminal is proposed to
be located in the centre of the island, as presented in the engineering layout
(Figure
9.1). Due to the existing platform of the
former detention camp, the majority of land needed for the terminal already
exists; however, small areas of reclamation will be required to the west and
east of the platform. Reclamation
on the eastern side of the platform will be required for the construction of a
sheltered anchorage and to the west for the third storage tank. A jetty to serve LNG carriers would be
located on the southern coast of
The South Soko LNG terminal will connect
to the Black Point Power Station via a submarine pipeline. The proposed alignment for the submarine
pipeline corridor is presented in Figure 9.2.
The route has been selected in order to maintain separation from the
existing Sha Chau and
Power and water supplies required for the
routine operation of the LNG terminal will be provided by a new submarine cable
and water main connecting
The Study Area for the marine ecology
baseline has incorporated the proposed alignment corridor for the submarine
pipeline connection to the Black Point Power Station and the reclamation areas.
9.1.2
Structure of the Annex
Following this introductory section, the
remainder of this Marine Ecological Baseline Annex is arranged as follows:
Section 9.2 – Presents a summary of the
legislation for the protection of species and habitats of terrestrial and
marine ecological importance and in
Section 9. 3 – Presents the baseline marine ecological
conditions at the
Section 9. 4 – Evaluates the ecological importance of
the habitats and species of the Study Area.
Section 9.5
– Summarizes the baseline
marine ecological conditions of the Study Area.
9.2
Legislative
Requirements and Evaluation Criteria
9.2.1
Introduction
This
section summarizes all legislative requirements and evaluation criteria for the
protection of species and habitats of marine ecological importance.
9.2.2
Legislative Requirements and Evaluation
Criteria
Legislative
requirements and evaluation criteria relevant to the study are as follows:
1.
Marine Parks Ordinance (Cap 476);
2.
Wild Animals Protection Ordinance (Cap
170);
3.
Protection of Endangered Species of
Animals and Plants Ordinance (Cap 586);
4.
Town Planning Ordinance (Cap 131);
5.
6.
The Technical Memorandum on Environmental
Impact Assessment Process under the Environmental Impact Assessment Ordinance
(EIAOTM);
7.
United Nations Convention on Biodiversity
(1992);
8.
Convention on Wetlands of International
Importance Especially as Waterfowl Habitat (the Ramsar Convention); and,
9.
PRC Regulations and Guidelines.
10.
9.2.3
Marine Parks Ordinance (Cap 476)
The
Marine Parks Ordinance provides for the designation, control and management of
marine parks and marine reserves.
It also stipulates the Director of Agriculture and Fisheries as the
Country and Marine Parks Authority which is advised by the Country and Marine
Parks Board. The
9.2.4
Wild Animals Protection Ordinance (Cap
170)
Under
the Wild Animals Protection Ordinance (Cap
170), designated wild animals are protected from being hunted, whilst their
nests and eggs are protected from destruction and removal. All birds and most mammals including all
cetaceans are protected under this Ordinance, as well as certain reptiles
(including all sea turtles), amphibians and invertebrates. The Second Schedule of the Ordinance
that lists all the animals protected was last revised in June 1997.
9.2.5
Protection of Endangered Species of
Animals and Plants Ordinance (Cap 586)
The
Protection of Endangered Species of
Animals and Plants Ordinance (Cap 586) was enacted to align
9.2.6
Town Planning Ordinance (Cap 131)
The
recently amended Town Planning Ordinance
(Cap 131) provides for the designation of areas such as “Coastal Protection
Areas”, “Sites of Special Scientific Interest (SSSIs)”, “Green Belt” and
"Conservation Area” to promote conservation or protection or protect
significant habitat.
9.2.7
Chapter 10 of the HKPSG
covers planning considerations relevant to conservation. This chapter details the principles of
conservation, the conservation of natural landscape and habitats, historic
buildings, archaeological sites and other antiquities. It also addresses the issue of
enforcement. The appendices list
the legislation and administrative controls for conservation, other
conservation related measures in
9.2.8
Technical Memorandum on Environmental
Impact Assessment Process under the Environmental Impact Assessment Ordinance
Annex 16 of the EIAOTM sets out the general approach and methodology for assessment
of ecological impacts arising from a project or proposal, to allow a complete
and objective identification, prediction and evaluation of the potential
ecological impacts. Annex 8 recommends the criteria that can
be used for evaluating ecological impacts.
9.2.9
Other Relevant Legislation
The
Peoples’ Republic of China (PRC) is a Contracting Party to the United Nations Convention on Biological
Diversity of 1992. The
Convention requires signatories to make active efforts to protect and manage
their biodiversity resources. The
Government of the Hong Kong Special Administrative Region has stated that it
will be “committed to meeting the environmental objectives” of the Convention
(PELB 1996).
The
Convention on Wetlands of International
Importance Especially as Waterfowl Habitat (the Ramsar Convention) applies
in the HKSAR. The Convention
requires parties to conserve and make wise use of wetland areas, particularly
those supporting waterfowl populations.
Article 1 of the Convention defines wetlands as "areas of marsh,
fen, peatland or water, whether natural or artificial, permanent or temporary,
with water that is static or flowing, fresh, brackish or salt, including areas
of marine water the depth of which at low tide does not exceed six
meters." The Mai Po/Inner Deep
Bay wetland was declared a Wetland of International Importance (“Ramsar site”)
under the Convention in 1995.
The
PRC in 1988 ratified the Wild Animal
Protection Law of the PRC, which lays down basic principles for protecting
wild animals. The Law prohibits
killing of protected animals, controls hunting, and protects the habitats of
wild animals, both protected and non-protected. The Law also provides for the creation
of lists of animals protected at the state level, under Class I and Class
II. There are 96 animal species in
Class I and 156 in Class II. Class
I provides a higher level of protection for animals considered to be more
threatened.
9.3
Marine Ecological
Resources - Background
9.3.1
Introduction
This section describes the baseline conditions of the marine ecological
resources at
Based on this review, an evaluation of the information collected was
conducted to identify any gaps that need to be filled in order to conduct an
assessment of ecological importance of the marine habitats. Where information gaps were identified, or where certain habitats or species were
considered to warrant further attention, field surveys have been conducted.
9.3.2
Site History
The
In terms of water quality, the island experiences estuarine conditions
owing its position at the eastern side of the
Most recently, the island was the location of a Detention Centre
operated by the Hong Kong Government.
As part of the construction of this facility a relatively large portion
of the coastline in Sai Wan, a sheltered bay on the west coast, and Tung Wan,
an exposed bay on the east coast, was reclaimed. Prior to this development, however, the
shoreline remained natural and mainly consisted of rocks, boulders and sandy
beaches.
Two areas designated and administered by the Civil Engineering and
Development Department (CEDD) of the Hong Kong Government for dredging and
disposal operations fringe the
9.3.3
Literature Review
Based on the literature review the following habitats and/or organisms
of ecological interest have been identified at
·
Hard
Bottom Habitats; and
-
Intertidal Hard Bottom Habitats
-
Subtidal Hard Bottom Habitats
·
Soft
Bottom Habitats;
-
Intertidal Soft Bottom Habitats
-
Subtidal Soft Bottom Habitats
·
Epifaunal
Assemblages
·
Infaunal
Assemblages
·
Marine
Mammals;
The existing conditions of each of the above habitats/organisms based on
available literature are presented in the following sections.
9.3.4
Hard Bottom Habitats
Approximately 80% of
Intertidal Hard Bottom Habitats
The intertidal habitat of
Previous surveys conducted as part of the focussed survey of the South
West Lantau marine habitats, recorded assemblages that were considered to be
typical of the habitat type in Hong Kong ([2]). The majority of species recorded were
considered to be common in
For this EIA Study, it was considered appropriate to conduct intertidal
surveys on
Subtidal Hard Bottom Habitats
Coral reefs support a range of species providing shelter, feeding,
spawning and nursery areas, resulting in the large and diverse community for
which they are renowned. The coral
reef system has been shown to be sensitive to pollution and impacts from
development can cause the ecosystem to collapse, resulting in widespread
mortality of coral and the numerous associated organisms. Natural fluctuations in water quality
can also regulate coral communities.
The Agriculture, Fisheries and Conservation Department report that there
are over 80 species of corals recorded in
A number of studies of the subtidal hard bottom habitats in vicinity to
the proposed South Soko LNG terminal have been conducted. In 1997, as part of the Coastal Ecology
Studies, commissioned by the Civil Engineering Department, qualitative dive
surveys of corals were conducted at the
In 1998, a study on Shek Kwu Chau, in the vicinity of the Soko Islands
identified coral habitats that were of low ecological value ([5])
. Few sporadic and isolated hard
coral communities were recorded, with considerable sedimentation on the
majority of hard surface substratum ([6]).
Recently, as part of a study of the marine habitats of South West Lantau,
dive surveys were conducted on the large granitic slabs and boulders of the
Surveys of subtidal hard bottom habitat in the vicinity of the proposed
submarine pipeline, submarine cable and watermain are limited. However, it should be noted that as
discussed above, the general trend for coral communities in Hong Kong is one of
increasing abundance and diversity from west to east with the greatest
diversity and abundance generally found in the eastern waters of
9.3.5
Soft Bottom Habitats
Intertidal Soft Bottom Habitats
As part of a recent territory wide study of
Two species of Horseshoe Crabs (Tachypleus tridentatus and Carcinoscorpius
rotundicauda) have been recorded in
Subtidal Soft Bottom Habitats
Epifaunal Assemblages
Subtidal soft bottom habitats, as well as supporting infaunal species,
commonly support macro-benthic epifauna.
These organisms are generally greater than 1mm in size and live either
on or within the surface sediments.
Data on epifaunal assemblages in
Information on the epifaunal assemblages in proximity to the proposed
LNG terminal on South Soko Island and along the Preliminary submarine pipeline
corridor has been taken from a review of the largest such study in Hong Kong, namely
the Agriculture, Fisheries and Conservation Department commissioned study on
Fisheries Resources and Fishing Operations in Hong Kong ([10]).
Surveys undertaken as part of this study indicates that that the highest
biomasses recorded in the waters around the
A more recent survey on epifaunal assemblages in and around the Soko
Islands and Shek Pik has been conducted in 1999 as part of a focussed survey on
the South West of Lantau ([11]). As part of this study, trawls were
conducted on the soft bottom habitats to characterise the epifauna of the
areas.
The majority of organisms collected in both wet and dry seasons were
either mantis shrimps or prawns, with the highest species diversity from small
fish or crabs. These species are
common in Hong Kong and are found in the majority of
A review of 10-years of data on fisheries resources collected from
demersal trawls conducted as part of the ongoing marine monitoring of
contaminated mud disposal at the East of Sha Chau Contaminated Mud Pits
provides data on epifaunal assemblages to the west of Lantau, in the vicinity
of Tai O and the Lung Kwu Chau and Sha Chau Marine Park ([12]). As these areas are in relatively close
proximity to the proposed pipeline route, these data can be considered to be
representative of the epifaunal assemblages in this area.
These data indicate that epifaunal assemblages are dominated by
gastropods (eg Turritella terebra),
crabs and mantis shrimps. Abundance
and species composition was considered to be relatively low in comparison to
other areas in
Based on the above, the epifaunal assemblages in the proposed study area
are considered to be of low abundance, diversity and biomass in comparison to
other areas of
Infaunal Assemblages
Soft sediments consisting of silt, clay and sand dominate the seabed of
Both the waters around the proposed terminal site as well as the waters
of the preliminary submarine pipeline corridor were surveyed as part of a Hong
Kong wide study conducted in 1976, however, the findings of this study are
considered to be no longer applicable due to the extensive development in both
Hong Kong and the Pearl River Estuary that was since occurred. This is supported by the findings of a
recent, second,
A comparison of the results of the 1976 study and the 2001 study found
that changes in benthic communities, particularly species composition had
occurred. This was reported as
being primarily as a result of a wider distribution and increase in abundance
of pollution tolerant species such as Prionospio
spp and Mediomastus spp.
The Seabed Ecology Studies were a Table 9.1) ([14]).
The findings of the study concluded that the sites in the southern waters,
where the proposed South Soko LNG terminal site is located, were found to have infaunal
assemblages of higher abundance, biomass and taxonomic richness when compared
to sites in the eastern waters of Hong Kong, however, similar if not lower when
compared to sites of increased habitat heterogeneity such as the Tathong
Channel. It was speculated that the
comparatively high values at the Soko MBA were as a result of the exhausted
sand borrow area in the vicinity of the sampling sites. The heterogeneity of habitat provided by
this substratum would likely have increased the infaunal assemblages in the
area. It is worth noting, however,
that the average weight per individual at the Soko MBA site was relatively low,
suggesting the abundance of opportunistic, low biomass colonising species
(polychaete worms).
Table 9.1 Comparison
of Data on Infaunal Assemblages at Eight Sites in
Comparative Note |
Study Site |
|||||||
|
|
|
East of Ninepins |
|
South Cheung Chau |
Eastern Waters |
Tathong Channel |
|
Abundance (no. m-2) |
468 |
240 |
294 |
2,187 |
2,080 |
352 |
3,130 |
1,674 |
Rank Abundance |
5 |
8 |
7 |
2 |
3 |
6 |
1 |
4 |
Biomass (g m-2) |
7.5 |
6.1 |
12.8 |
35.7 |
47.2 |
32.9 |
35.7 |
30.6 |
Rank Biomass |
7 |
8 |
6 |
2 |
1 |
4 |
2 |
5 |
Diversity (families grab-1) |
7 |
13 |
12 |
21 |
15 |
12 |
22 |
16 |
Rank Diversity |
8 |
5 |
6 |
2 |
4 |
6 |
1 |
3 |
Average weight per individual (total g m-2/
total no. m-2) |
0.0016 |
0.026 |
0.044 |
0.017 |
0.023 |
0.094 |
0.012 |
0.019 |
Rank weight per individual |
7 |
3 |
2 |
6 |
4 |
1 |
8 |
5 |
Average Rank |
6.75 |
6 |
5.25 |
3 |
3 |
4.25 |
3 |
4.25 |
Note: Shaded cells indicate highest ranking.
The findings that opportunistic colonisers
make up the majority of the infaunal assemblages in the soft bottom habitat in
the vicinity of the Soko Islands was supported by the Hong Kong wide benthic
surveys conducted in 2001 ([16]). Due to the extensive survey effort
undertaken as part of this study, the results provide up-to-date information on
the infaunal assemblages both within close proximity to the proposed LNG
terminal and along the proposed submarine pipeline corridor (Table 9.2Table 9.2).
Table 9.2 Comparison
of Data on Infaunal Assemblages at four areas in vicinity of the proposed South
Soko LNG Terminal and the Submarine Pipeline, Cable and Watermain Routes, Data Collected
in the Study on Marine Benthic Communities in Hong Kong, 2000 – 2001 ([17]).
Comparative Note |
Lung Kwu Chau and Sha Chau |
|
|
Shek Pik |
||||
|
Wet Season |
Dry Season |
Wet Season |
Dry Season |
Wet Season |
Dry Season |
Wet Season |
Dry Season |
Abundance
(no. m-2) |
143 |
406 |
426 |
1,436 |
811 |
1,245 |
810 |
432 |
Biomass
(g m-2) |
14.52 |
7.98 |
4.08 |
37.62 |
46.99 |
55.47 |
118 |
36.66 |
Diversity (species 0.5 m-1) |
23 |
56 |
34 |
38 |
64 |
70 |
69 |
59 |
The findings of the CityU study were that
the stations at the
Based on the findings of comparatively high abundance, biomass and
diversity of the infaunal assemblages in the soft bottom habitats in the waters
surrounding the
9.3.6
Marine Mammals
A total of 16 (and possibly up to 18) species of marine mammals, or
cetaceans, have been recorded in
Studies on the distribution, abundance, habitat use, and life history of
humpback dolphins within
Historically, marine mammal data have been presented in terms of
sightings ([24]). Recent analysis adopted in the marine
mammals monitoring study ([25])
has allowed data to be standardised to reflect numbers of sightings in terms of
survey effort. Such data are
considered to be closer to a direct indication of abundance and habitat usage
than raw observational data. In
order to utilise the most up-to-date data, yet still allow comparison with
previous studies to be made, both types of data will be discussed.
Abundance of humpback dolphins in
Humpback dolphins exhibit a seasonal shifting in abundance and density
and thus a seasonal variation of abundance in different locations. The variation is thought to be due to
the increased input of freshwater from the discharge of the Pearl River Estuary
and the subsequent movements of estuarine prey species ([26]) ([27])
([28])
.
Recently published information indicates that the abundance of dolphins
in
Historical data on the utilisation of the waters around the proposed LNG
terminal on
In contrast to humpback dolphins,
studies on the finless porpoise indicated that the majority of sightings in the
long-term dataset have been recorded in the southern and eastern waters of
As with humpback dolphins, distribution of finless
porpoise in
The recent studies on marine mammals in
Based on the results of the information available from the long term
sighting data on marine mammals in the waters of Hong Kong, it appears that
sightings of both of Hong Kong’s resident cetacean species, Sousa chinensis and Neophocaena phocaenoides have been recorded within the waters
surrounding the proposed LNG terminal on South Soko Island. Sightings of Sousa chinensis have also been recorded in the waters of the
preliminary submarine pipeline corridor.
In order to provide up-to-date and detailed comprehensive baseline
information to supplement information from the literature, a programme of
marine mammal surveys was undertaken for this EIA Study. A dual survey approach was adopted so
that both land-based surveys on Table 9.3). It
is important to note that the data generated by these two different survey
approaches was intended to serve different purposes. Overall, the survey programme was
specifically designed to focus on gathering information on marine mammal
utilisation of waters around the
Land-based surveys, on the other hand, were undertaken with the aim of
closely focusing on marine mammal utilisation of nearshore waters in the
vicinity of the proposed LNG terminal location. The results yielded from the land-based
survey are qualitative in nature and cannot be used for quantitative
determination of marine mammal abundance.
Land-based surveys, nevertheless, serve a useful purpose by providing
supplementary information for the assessment. While the vessel-based surveys provide
ample data to conduct the assessment, when taken together the vessel-based and
land-based provide a highly detailed database of marine mammal information for
this assessment.
9.3.7
Baseline Marine Ecological Surveys
The literature review of the marine
ecological habitats and resources of the waters within, and in close proximity
to, the proposed LNG terminal at Table 9.3).
Table 9.3 The
Marine Ecology Baseline Surveys (Location refer to Figures 9.5& 9.6)
Survey Type |
Methodology |
Date |
Intertidal
Assemblages at |
Rocky shore/ artificial shoreline Quantitative (belt transects at 9
locations) survey, three 100 m belt transects (at high, mid and low intertidal
zones) for each location, covered both wet and dry seasons. Quantitative
(line transects at two locations) survey, 50 x 50 x 50cm core at three points
(high, mid and low intertidal zones) along
each of the transects, covered
both wet and dry seasons. |
8
& 9 March, 28 & 29 July and 14 September 2004, 17 & 28 December
2004, 29 & 30 September 2005 and 27 January 2006 |
Intertidal
Assemblages at Black Point |
Rocky shore/ artificial shoreline Quantitative
(belt transects at 6 locations) survey, three 100 m belt transects (at high,
mid and low intertidal zones) for each location, covered both wet and dry
seasons |
22
& 23 March and 15 & 30 July 2004. |
Intertidal
Assemblages at Shek Pik |
Rocky shore/ artificial shoreline Quantitative (belt transects at 1
locations) survey, three 100 m belt transects (at high, mid and low
intertidal zones) covered both wet and dry seasons. Quantitative
(line transects at 3 locations) survey, 50 x 50 x 50cm core at three points (high,
mid and low intertidal zones) along each of the transects,
covered both wet and dry seasons. |
30
August 2005 & 14 March 2006 |
Subtidal Benthic Assemblages |
Quantitative grab sampling survey;
covered both wet and dry seasons. Six stations sampled in each of 14
locations. |
25
& 26 February, 5 & 6 July, 9 September and 8 November 2004, 23
September 2005 and 13 December 2005 |
Subtidal
Hard Bottom Habitat (Coral) |
Quantitative (Rapid Ecological Assessment
(REA) technique, a total of twenty three 100 m transects at 15 locations) and
qualitative (recorded within Study Area and areas in the vicinity, 3
locations); covered wet season. |
9
& 15 May 2004, 29,30 September & 3 October
2005. |
Marine
Mammal * |
Land-based visual survey during daytime,
5 days per month and 6 hours per day, covered four seasons and 12 months. |
13,
14, 21, 23 & 26 February, 8, 9, 10, 17 & 18 March, 16, 19, 20, 21
& 26 April, 10, 12, 14, 19 & 25 May, 10, 14, 17, 18 & 28 June
2004, 23, 26, 27, 28 & 29 July 2004, 25, 26, 27, 30 & 31 August, 6,
7, 13, 14 & 22 September 2004, 27, 28, 29, 30 & 31 October 2004, 16,
17, 24, 25 & 26 November 2004, 16, 21, 28, 30 & 31 December 2004, 10,
12, 14, 17 & 28 January 2005 |
|
Quantitative
vessel based survey using line transect methods spanning Hong Kong western
waters (Deep Bay, Southwest Lantau, Northwest Lantau and West Lantau) 6 days
per month. |
18,
19, 20,,21, 22, 25, 26, 27 July 2005, 3, 4, 5,15,24 & 25 August 2005,
5,7,15, 16 & 20 September 2005, 5, 6, 7, 17, 18 & 19 October 2005,
22, 24, 25, 28, 29 & 30 November 2005, 6,7,8 & 22 December 2005, 13,
16, 17, 19, 20 & 24 January 2006, 1, 2, 3, 7, 8 & 9 February 2006,
17, 23, 28, 29, 31 March 2006, 3, 6, 18, 25, 26, 27 April 2006, 2, 4, 8, 9,
10, 11 May 2006. |
Note: *
Vessel-based surveys covered the period July 2005 – May 2006.
No surveys were considered necessary for
epifaunal assemblages as a review of the available literature provided sufficient
evidence of a low ecological value habitat in the waters surrounding the
proposed LNG terminal on
Survey methodologies have been selected to
follow standard and accepted techniques for marine ecological surveys. In addition, each methodology has been
previously conducted as part of other Environmental Impact Assessments (EIA)
studies, accepted under the Hong Kong Environmental Protection Department Environmental Impact Assessment Ordinance
(EIAO).
Survey schedules were undertaken in accordance with the Environmental Impact Assessment Ordinance,
Cap.499 Guidance Note - Ecological Baseline Survey For
Ecological Assessment, specifically in terms of the following:
·
Duration
of Survey;
·
Seasonality;
·
Types
of Survey Period; and
·
Survey
Effort.
The following sections present the methodology and results for each
marine ecological survey undertaken as part of the assessment of marine
ecological baseline conditions.
9.3.8
Intertidal Habitats
Methodology
Survey Locations
Both rocky and sandy intertidal habitats were surveyed. On the shores of
Owing to reclamation at Black Point required for a Gas Receiving
Station, surveys, six quantitative rocky shore surveys were conducted on the
shores of Black Point, of which two were on natural rocky coastline and four on
artificial rocky coastline.
In addition, a quantitative transect survey was conducted at one site on
natural rocky shore at Shek Pik where the submarine cable and watermain would
land. In addition, quantitative
surveys were conducted on the sandy shore.
Qualitative surveys were also undertaken in the surrounding areas of the
landing site of the submarine cable and watermain. Owing to the presence of Shek Pik Prison
access to the western shores of
The survey transects were presented in Figures 9.5 & 9.6.
Survey Methodology
Rocky Shore and Artificial Shoreline
A 100m
transect tape was laid horizontally along the rocky and artificial shoreline at
2 metres above chart datum (CD).
When tidal height was below 1m, transects could be started, local tide
tables were used to assess tidal height at the site and times of surveys were
adjusted accordingly. Random
numbers between 1 and 100 were generated before the survey and these numbers
corresponded to metres along the transect at which
quadrats should be placed. Three
sets of random numbers were generated per transect to represent upper, mid and
low transects.
A
50cm x 50cm quadrat was used to assess abundance and distribution of flora and
fauna. All fauna found within the
quadrat were recorded to species level to allow density per square metre to be
calculated. Sessile fauna such as
barnacles and oysters recorded in samples were not counted but estimated as
percentage cover on the rock surface.
Species of algae (encrusting, foliose and filamentous) were also
identified and recorded by estimating the percentage cover within the sample
quadrat.
On the south coast of
On
sandy shores, three line transects were deployed from the low tide mark up to
the high tide mark and the presence of organisms were noted. At three points (1m, 1.5m and 2m above
CD) along each of the transects, a 50 x 50 x 50cm core was removed and
carefully sorted. All macrofauna
visible to the naked eye within the sample core were identified and recorded.
Results of Intertidal Surveys at
Intertidal surveys have been conducted over two seasons, wet and
dry. The date of each survey at
each location is presented in Table 9.4Table 9.4.
There were three types of coastal habitats, including sandy shore,
natural rocky shore and artificial shoreline, recorded within the Study Area (Figure 9.7).
Table 9.4 Description
of the Survey Transects/ Spotchecks and Survey Dates for Intertidal Hard Bottom
Surveys on
Transect |
Site Description |
Date of Survey |
|
|
|
Dry Season |
Wet Season |
Artificial
Shoreline |
|
|
|
T1 |
Located in Sai Wan, shoreline is made up
of large boulders and is relatively steep. |
8 Mar 2004 |
28 July 2004 |
T2 |
Large granite boulders make up the
majority of the substrate on this relatively steep sided shoreline |
8 Mar 2004 |
28 July 2004 |
T3 |
Located in Sai Wan, the shoreline was
disturbed. |
8 Mar 2004 |
29 July 2004 |
T7 |
Large granite boulders make up the
majority of this steep rocky artificial coastline. |
28 Dec 2004 |
14 Sept 2004 |
Rocky
Shore |
|
|
|
T4 |
Located in Sai Wan, natural shallow
sloping rocky shoreline consisting of mixture of smaller boulders at the low
tide mark gradually getting larger further up the shoreline. |
9 Mar 2004 |
29 July 2004 |
T5 |
Located in Pak Tso Wan, natural shallow
sloping rocky shore line consisting of mixture of smaller boulders at the low
tide mark gradually getting larger further up the shoreline. |
9 Mar 2004 |
29 July 2004 |
T6 |
Transect 6 is a very steep natural
shoreline on the northern shoreline of Tung Wan. |
17 Dec 2004 |
14 Sept 2004 |
T8 (SC) |
Located on southwest coast, shore is
very steeply sloped bedrock |
27 Jan 2006 (spotcheck) |
29 Sept 2005 (spotcheck) |
T9 |
Rocky shore comprised large scattered
boulders, which is located in a small bay on the south side of the island |
27 Jan 2006 (spotcheck) |
29 Sept 2005 |
T10(SC) |
Shore was inaccessible but was observed
to be comprised of large boulders |
27 Jan 2006 (spotcheck) |
29 Sept 2005 (spotcheck) |
T11(SC) |
Steep inaccessible rocky shore with
large boulders |
27 Jan 2006 (spotcheck) |
29 Sept 2005 (spotcheck) |
T12(SC) |
Steep impassible bedrock with large
boulders on the south side of the island |
27 Jan 2006 (spotcheck) |
30 Sept 2005 (spotcheck) |
T13(SC) |
Steep, inaccessible rocky headland on
south coast. |
27 Jan 2006 (spotcheck) |
30 Sept 2005 (spotcheck) |
T14 |
Shallow sloping boulder shore comprising
medium and large sized boulders with occasional patches of sand and shell
debris. |
27 Jan 2006 (spotcheck) |
30 Sept 2005 |
T15(SC) |
Steep jagged boulders and steep sloping
bedrock and large boulders. |
27 Jan 2006 (spotcheck) |
30 Sept 2005 (spotcheck) |
|
|
|
|
|
|
|
|
SS1 |
Located in Sai Wan, moderately sloping
shoreline made up of reasonably coarse grained sand. |
9 Mar 2004 |
29 July 2004 |
SS2 |
Located in Tung Wan, the beach is moderately
sloping and made up of medium grained sand. |
17 Dec 2004 |
14 Sept 2004 |
Rocky Shore and
Artificial Shoreline
Dry Season
Rocky shore flora and fauna present on the shore at South Soko recorded during
the dry season were common and widespread species, typical of semi exposed
rocky shores in
The distribution of intertidal biota at different tidal heights on the shore
followed typical vertical zonation patterns found in
The high shore was dominated by the littorinid snails (periwinkles), Nodolittorina spp. Particularly on the wave exposed areas,
stalked barnacles, Capitellum mitella
occurred in crevices into the high shore.
On the mid and low shore were found a variety of marine snails
(including Monodonta labio, Thais clavigera, Nerita albicilla, Planaxis
sulcatus, Lunella coronata and Chlorostoma
arygrostoma), limpets (including Cellana
toreuma, Nipponacmea concinna, Patelloida pygmea, Patelloida saccharina, Siphonaria
japonica and Siphonaria lacinosa)
barnacles (including Tetraclita japonica,
Tetraclita squamosa, Capitellum mitella, Megabalanus volcano and
Balanus amphitrite) and bivalves (including Saccostrea cucullata, Septifer virgatus and Barbatia virescens).
Other fauna found on the shore included tubeworms (Hydriodes sp.), crabs (Grapsus
albolineatus and Hemigrapsus
sp.), chitons (Acanthopleura japonica),
sea anemones (Haliplanella lineata)
and rockpool fish (Bathygobius fuscus).
Algal cover recorded in the dry season was dominated by the encrusting
algae Pseudulvella applanata and Hildenbrandtia rubra at the mid shore
and erect red turf algae, Gelidium pusillum at the low shore. Other algae
recorded incuded Ulva sp., pink
encrusting algae, Endarachne binghamiae,
Hincksia mitchelliae, Sargassum sp., and the cyanobacteria Kyrtuthrix maculans.
Wet Season
The species composition of the intertidal
organisms during the wet season was similar to that of the dry season, with a
total of 48 species on the rocky shore and 22 species on artificial shoreline (Tables 4, 5 & 6 of Annex 9-A). The major differences between the
seasons were the abundance of littorinid snails and rock oyster. The abundance of littorinid snails
recorded during the wet season was much lower than those recorded during dry
season, and vice versa for rock oyster.
The total abundance of the intertidal organisms recorded in wet season
was generally lower than the dry season.
The sandy shores at
Results of Intertidal Surveys at Black
Point
Intertidal surveys have been conducted
over two seasons, wet and dry. The
date of each survey at each location is presented in Table 9.5. There
were two types of coastal habitats, including natural rocky shore and
artificial shoreline, recorded within the Study Area (Figure 9.8).
Table 9.5 Description
of the Survey Transects and Survey Dates for Intertidal Hard Bottom Surveys at
Black Point
Transect |
Site Description |
Date of Survey |
|
|
|
Dry Season |
Wet Season |
Natural
Shoreline |
|
|
|
T1 |
Transect 1 is the furthest south of the
rocky shore transects at Black Point and is a very steep natural shoreline
made up of bedrock and the occasional boulder. |
23 Mar 2004 |
15 July 2004 |
T2 |
Bedrock interspersed with a few large
boulders and ranges from very steep to moderately steep sloping rock faces. |
23 Mar 2004 |
15 July 2004 |
Artificial
Shoreline |
|
|
|
T3 |
Southernmost artificial shoreline to the
power stations cooling water outlet.
Site consisted of steep large boulders. |
23 Mar 2004 |
15 July 2004 |
T4 |
South of the power stations cooling
water outlet. Steep artificial
seawall consisting of large boulders. |
22 Mar 2004 |
30 July 2004 |
T5 |
Adjacent to the power stations cooling
water outlet. Steep artificial seawall
consisting of large boulders. |
22 Mar 2004 |
30 July 2004 |
T6 |
Located on the artificial shoreline on
northern |
22 Mar 2004 |
30 July 2004 |
Rocky Shore and
Artificial Shoreline
Dry Season
The littorinid snails, including Nodilittorina
radiata, N. vidua and Littoraria
articulata, were the dominant
species in the high intertidal zone on the rocky shore and artificial shoreline
during the dry season at Black Point (Tables
8 and 10 of Annex 9-A). The
predatory gastropod Thais clavigera
(the common dogwhelk), limpets (ie Nipponacmea
concinna and Siphonaria japonica) and snail (Monodonta
labio and Planaxis
sulcatus) were recorded in the
mid and low shore region. Sessile
filter-feeding organisms such as the rock oyster (Saccostrea cucullata) and barnacles (Capitulum mitella, Tetraclita
japonica, T.squamosa, Balanus amphitrite) were
also recorded on the shores (Tables 8 and
10 of Annex 9-A). There were
only 2 types of algae, including Ulva
sp. and encrusting algae, of low coverage recorded at Black Point during the
dry season surveys.
In total, there were 21 species recorded on the natural and artificial
shores. 12 species recorded on
natural shoreline were also found on artificial shoreline (Tables 1 and 4 of Annex 9-A). Except littorinid snails, all of the
recorded species were in low abundances.
Wet Season
The species composition of the intertidal organisms
during the wet season is similar to that of the dry season, with a total of 15
species on artificial shore and 12 species on natural shoreline (Tables 9 and 11 of Annex 9-A). The major differences between the
seasons were the abundance of littorinid snails and rock oyster. The abundance of littorinid snails
recorded during the wet season were much lower than
those recorded during dry season, and vice versa for rock oyster. The total abundance of the intertidal
organisms recorded in wet season was generally lower than the dry season.
Results of Intertidal Surveys at Shek Pik
Intertidal surveys have been conducted
over two seasons, wet and dry. The
date of each survey at each location is presented in Table 9.6Table 9.6.
There were two types of coastal habitats,
rocky shore and sandy shore (Figure 9.9).
Table 9.6 Description
of the Survey Transects and Survey Dates for Intertidal Hard Bottom and
Intertidal Soft Bottom Surveys at Shek Pik
Transect |
Site Description |
Date of Survey |
|
|
|
Dry Season |
Wet Season |
Natural
Rocky Shoreline |
|
|
|
T1 |
Transect 1 is located on the east coast
of Tung Wan and consisted of sheltered shallow sloping rocky shore consiting
of bedrock and medium size boulders. |
14 March 2006 |
30 August 2005 |
Sandy
Shoreline |
|
|
|
T2, T3, T4 |
Transects were laid on the sandy shore
located next to the pier. |
14 March 2006 |
30 August 2005 |
Rocky Shore
Dry Season
The rocky shore supported a low diversity of flora and fauna. The shore was dominated by the rock
oyster, Saccostrea cucullata and with
a high cover of Enteromorpha
macroalgae. All biota are common
and widespread and no species of note were found during the survey.
Wet Season
Surveys indicated low abundance and relatively low diversity of rocky
shore fauna consiting of a species which are common and widespread in
Dry Season
Survey of the sandy shore during the dry season encountered several
borrows of the common Ghost Crab Ocypode
cordimana. This shore appeared
to be devoid of other burrowing or surface-dwelling fauna.
Wet Season
Survey on the sandy shore at Shek Pik encountered no fauna.
9.3.9
Comparison of South Soko Intertidal
Habitats With Other
The intertidal organisms found on
|
Figure 9.10 Comparison
of Intertidal Fauna and Flora at Various Sites in
9.3.10
Subtidal Hard Bottom Habitats
Methodology
The Rapid Ecological Assessment (REA) technique was employed in order to
investigate the subtidal hard bottom habitat assemblages at the proposed LNG
terminal on
Survey Locations
Survey locations were selected in order to provide detail on the hard
bottom habitats both within the proposed development area of the LNG terminal
at
Quantitative Surveys
·
·
·
·
·
West
Tung Wan (Zone E1)
·
North
Tung Wan (Zone E2)
·
·
Lan Nai Wan (Zone E4)
·
South
Tai A Chau (Zone I)
·
South Tai A Chau (Zone J)
·
South
Tai A Chau (Zone K)
·
South
Tai A Chau (Zone L)
·
South
Tai A Chau (Zone M)
·
South
Tai A Chau (Zone N)
·
South
Tai A Chau (Zone O)
·
South Tai A Chau (Zone P)
·
Yuen Kong Chau (Zone Q)
·
Tai Lo Chau (Zone R)
In addition to the above, three locations were surveyed qualitatively,
as follows:
·
Ma
Chau (Zone F)
·
Yeung
Chau (Zone G)
·
Outer Sai Wan (Zone H)
A summary of the dive surveys is presented below in Table 9.7Table 9.7, and locations are shown in Figure 9.5.
Table 9.7 Number
of Transects Surveyed at
Survey Site |
Number of 50m Transects Surveyed |
Total Length of Area Surveyed |
Zone A |
1 in shallow depth zone and 1 in deep
depth zone |
100m |
Zone B |
1 in shallow depth zone and 1 in deep
depth zone |
100m |
Zone C |
1 in shallow depth zone and 1 in deep
depth zone |
100m |
Zone D |
1 in shallow depth zone and 1 in deep
depth zone |
100m |
Zone E |
4 in shallow depth zone and 4 in deep
depth zone |
400m |
Zone F |
Qualitative survey in both shallow and
deep depth zones |
|
Zone G |
Qualitative survey in both shallow and deep
depth zones |
|
Zone H |
Qualitative survey in both shallow and
deep depth zones |
|
Zone I |
1 in shallow depth zone |
100m |
Zone J |
1 in shallow depth zone |
100m |
Zone K |
1 in shallow depth zone |
100m |
Zone L |
1 in shallow depth zone |
100m |
Zone M |
1 in shallow depth zone |
100m |
Zone N |
1 in shallow depth zone |
100m |
Zone O |
1 in shallow depth zone |
100m |
Zone P |
1 in shallow depth zone |
100m |
Zone Q |
2 in shallow depth zone |
200m |
Zone R |
3 in shallow depth zone and 2 in deep
depth zone |
500m |
Total |
23 |
1900m |
Rapid Ecological Assessment (REA) Survey Method
REA surveys were undertaken using standard SCUBA equipment. An initial qualitative reconnaissance dive
was conducted within the study area and based on this, a decision was made on
site as to where to position transects.
Areas where corals appeared to be the most abundant, or areas of high
epifaunal density, were selected as preferred locations. As such, the coordinates of the chosen
transects were identified in the field using a handheld Geographic Positioning
System (GPS) unit and recorded for future reference.
REA Transects for Zones A to E were laid in two distinct depth zones
·
Shallow
depth zone: -2 to –5m
CD and;
·
Deep
depth zone:
-6
to –10m CD.
The depths of the transects were adjusted
accordingly based on the substrate habitats and the presence or absence of hard
and soft corals.
REA Transects for Zones I to Q were ~100m long and deployed in the
shallow depth zone (-2 to -5/-6m).
In the turbid western waters, it is known that 6m is typically the depth
limit at which hermatypic hard corals grow due to prevailing highly turbid
conditions. At Zone R, survey
conditions allowed survey transects to be deployed along deep depth zone in
addition to shallow depth zone.
Following the laying of the transect line, video footage was taken of
the benthos along the transect and an assessment of the benthic cover (Tier I)
and taxon abundance (Tier II) was undertaken in a swathe ~ 4 m wide, 2 m either
side of each transect. Swimming speed whilst videoing was kept slower than 10m per minute
to prevent blurring of video and to improve clarity. An explanation of the two assessment
categories (Tiers) used in the surveys is presented below.
Tier I - Categorisation of Benthic Cover
Upon the completion of each transect, six ecological and seven
substratum attributes were assigned to one of seven standard ranked (ordinal)
categories (Table 9.8Table 9.8 and Table 9.9Table 9.9).
Table 9.8 Benthic
Attribute Categories
Ecological |
Substratum |
Hard coral |
Hard substrate |
Dead standing coral |
Continuous pavement |
Soft coral |
Bedrock |
Antipatharia |
Rubble |
Macroalgae |
Sand |
Turf algae |
Silt |
|
Boulders – large (>50cm), small
(<50cm) |
Table
9.9 Ordinal
Ranks of Percentage Cover
Rank |
Percentage Cover (%) |
0 |
None recorded |
1 |
<5 |
2 |
6-10 |
3 |
11-30 |
4 |
31-50 |
5 |
51-75 |
6 |
76-100 |
Tier II - Taxonomic Inventories to Define
Types of Benthic Communities
An inventory of benthic taxa was compiled during each dive (ie each transect). Taxa
were identified in situ to the
following levels:
·
Scleractinian
(hard) corals to species wherever possible;
·
Soft
corals, anemones and conspicuous macroalgae were recorded according to
morphological features and to genus level if possible.
·
Other
benthos (including sponges, zoanthids, ascidians and bryozoans) were recorded
to genus level wherever possible but more typically to phylum plus growth form.
At the end of each dive, each taxon in the inventory was ranked in terms
of abundance in the community (Table 9.10Table 9.10).
These broad categories rank taxa in terms of relative abundance of
individuals, rather than the contribution to benthic cover along each
transect. The ranks are subjective
assessments of abundance, rather than quantitative counts of each taxon.
Table 9.10 Ordinal
Ranks of Taxon Abundance
Rank |
Abundance |
0 |
Absent |
1 |
Rare |
2 |
Uncommon |
3 |
Common |
4 |
Abundant |
5 |
Dominant |
Photographs of representative coral species located in the surveyed
areas were taken and, where possible, photographs of the seabed composition
were taken.
Results of Subtidal Hard Bottom Habitat
Surveys
The surveys were performed on 9 May and 15 May 2004 as well as on 29 and
30 September and 3 October 2005. On
all dates, the weather was sunny and the sea was calm. The visibility was poor and generally
ranged between 0.3 m and 1.0 m and deteriorated with depth. Along each transect the seabed
composition was identified and conditions were noted as shown in Table 9.11Table 9.11 and Table 9.12Table 9.12.
Coral Assemblages
Dive surveys at South Soko for this EIA Study yielded similar results as
BCL (1997) ([44])
who reported that hard corals were in low abundance and diversity and dominated
by species which are common in Hong Kong.
In total, fifteen hard coral species and four octocoral species, were recorded within the Study Area (Table 9.13Table 9.13). The majority were common faviids,
poritids and siderasteriids with three predominant species – Oulastrea crispata, Psammocora sp. and
the ahermatypic cup coral Balanophyllia sp.. Corals
occurred in extremely low abundance and percentage cover estimates ranged from
1-5%. Many live corals recorded
were highly bioeroded by macroborers and barnacles. The majority of colonies exhibited
partial mortality and at most survey sites a low percentage cover of dead coral
was noted. Corals recorded are all
common
Following a recent AFCD commissioned study
which among other goals, aimed to clarify the taxonomic identity of Hong Kong
hard corals, the number of species known to be present in Hong Kong waters rose
from about 50 to over 80 ([45]). Pseudosiderastrea
tayami was among the recent discoveries on the revised
Site J, which is a small sheltered bay on
the south coast of
Table 9.11 Description
of the Seabed Recorded Along Each Transect and The
Qualitative Surveys
Transect |
Depth |
Description |
A (shallow) |
-3 mPD |
The seabed was composed of mainly bedrock and boulders
with sparse sandy substrate along the transect. No hard coral colonies were
found. Small number of poorly growth of Euplexaura
and coralline algae found at the hard surface. |
A (deep) |
-6 mPD |
The seabed was mainly composed of sandy substrate with
scattered boulders and rubbles.
Only one colony of Euplexaura
found. |
B (shallow) |
-1 to - 3 mPD |
The seabed was mainly composed of boulders with sand and
rubbles in between. Small number of poorly growth of Euplexaura
were recorded. |
B (deep) |
-4 to –4.5 mPD |
The seabed was composed of silt and prone sandy
substrate. No sessile organisms
were recorded. |
C (shallow) |
-1.2 to –3 mPD |
The seabed was composed of boulders and
in some parts with sand. The transect can be divided into 2 zones. The first zone (0-30m) was composed of
boulders with scattered rubbles and cobbles. The second zone (30-50m) was mainly
sandy with heavy silt. A common
hard coral colony Oulastrea crispata
was recorded along the transect. |
C (deep) |
-4 to –5 mPD |
The seabed was composed of fine sand. No sessile organisms were recorded. |
D (shallow) |
-1 to -3 mPD |
The seabed was mainly composed of sandy substrate with sparse
boulders and rubbles along the transect. No corals were recorded. |
D (deep) |
-4 mPD |
The seabed was mainly composed of silt and sandy
substrate. No sessile organisms
were recorded. |
E1 (shallow) |
-2.5 to -3 mPD |
The seabed was composed of boulders and cobbles. Macro-algae grew well on the surface
of the hard substrate. No hard
corals were recorded along this transect. |
E1 (deep) |
-6.5 mPD |
The bottom was composed of sandy
substrate. No sessile organisms
were recorded along this transect. |
E2 (shallow) |
-4.5 mPD |
The bottom was composed of sandy
substrate. Sponge, macro-algae,
coralline algae were recorded on the hard substrate. No corals were recorded. |
E2 (deep) |
-6 to -7 mPD |
The bottom was composed of sandy
substrate with some rubble patches.
About ten colonies of hard coral were recorded including Porites lobata, Psammocora superficialis, Echinophyllia sp, Favites abdita, Goniopora stutchburyi, Goniopora lobata and Oulastrea crispata. These colonies were scattered along the transect. |
E3 (shallow) |
-5 to –6mPD |
The bottom was composed of bed rock and
boulder. There were a number of
octocorals including Dendronephthya and
Euplexaura but the growth form and
size was limited. An ahermaptypic
coral Tubastrea was recorded. |
E3 (deep) |
-9mPD |
The bottom was composed of sand
substrate with some boulders and rubbles. Small number of octocorals including Dendronephthya and Euplexaura. An ahermaptypic coral Tubastrea sp. was also recorded. |
E4 (shallow) |
-4mPD |
The bottom was composed of bed rock,
boulder and sand. Small number of
octocorals including Dendronephthya and
Euplexaura. |
E4 (deep) |
-10mPD |
The bottom was composed of sand substrate
with some boulders and rubbles.
Small number of octocorals including Dendronepthya and Euplexaura. |
F |
-3 to –9mPD |
The bottom was composed of boulders,
rubbles and sandy substrate in the shallow water. Small number of Euplexaura sp. were recorded.
Some of the hard surfaces were covered with macro-algae. The deep region was mainly silt
substratum and devoid of marine life. |
G |
-3 to –9mPD |
In the shallow water, the bottom was
composed of boulders and rubbles.
Small number of Euplexeura
sp. were recorded but their condition was very poor. |
H |
-3 to –5mPD |
The bottom was mainly composed of sandy
substrate. |
I (shallow) |
-2 to -6.4 mPD |
Site comprised of large boulders with a
visible layer of silt. Absence of
coralline algae notable and sessile benthos comprised of isolated encrusting
sponges and bryozoans, small, scattered hard coral colonies of three species:
Oulastrea crispata, Psammocora sp. and the ahermatypic cup
coral Balanophyllia sp. (the most
abundant and recorded as common).
Isolated octocorals were recorded and included small colonies of Dendronephthya and the gorgonian Euplexaura. Ahermatypic cup coral Dendrophyllia/Tubastrea sp. was recorded at 5-6m depth. |
J (shallow) |
-1.2 to -5.6 mPD |
Site J encompassed a small sheltered and
depositional bay of the southern section of |
K (shallow) |
-2 to -5.4 mPD |
This site was similar to site J in terms
of substratum and sessile benthos composition. Pseudosiderastrea
tayami colonies were recorded as rare in abundance and the hard corals Oulastrea crispata, Psammocora sp., Porites lobata, Coscinaraea
sp. and the ahermatypic cup corals Balanophyllia
sp. and Dendrophyllia/Tubastrea sp.
were all recorded in low abundances.
A similar sessile invertebrates were observed
as at site J with a dominance of encrusting sponges and bryozoans. |
L (shallow) |
-2 to -5 mPD |
Site had a low abundance of hard corals:
Oulastrea crispata, Psammocora sp., Balanophyllia sp., the poritid Goniopora stutchburyi and the faviid Lepastrea pruinosa. The ahermatypic cup coral Dendrophyllia/Tubastrea sp. and gorgonian Echinomuricea were recorded from
deeper depths. Coralline algae
was dominant in the upper shallows (0-2 m depth) and large boulder surfaces
were encrusted with bryozoans, sponges, oysters, spiral tube worms and hydroids. |
M (shallow) |
-1 to -6 mPD |
Site composed of large boulders. Hard
corals recorded included: Oulastrea
crispata (common), Goniopora
stutchburyi, Psammocora sp.,
and Coscinaraea sp.. The ahermatypic cup coral Balanophyllia sp. was recorded as common and located on
horizontal boulder surfaces, generally below 5 m depth. |
N (shallow) |
-2 to -7 mPD |
Site encompassed a headland
promontory. On the southeast side
the benthic community was similar to I-M. On the northwest facing side of this
headland there was less deposition, clean boulder surfaces and visibility
improved to approximately 2 m due to a swift current running between |
O (shallow) |
-1 to -5 mPD |
A shallow site composed of small
boulders leading to a sandy sloping seabed. Upper, shallow sections were composed
of small boulders covered in encrusting corallines, barnacles and
oysters. Lower, shallow sections
were composed of scattered small boulders and sand. Benthic community composition was
comprised of bryozoans, encrusting sponges, small sea urchins and sea
cucumbers. This site recorded
seven species of hard coral with majority noted as uncommon in
abundance. The faviid Leptastrea pruinosa was common and
colonies >40 cm diameter were noted. Other
faviids included Cyphastrea sp. and
Oulastrea crispata. Other corals were Psammocora sp. , Coscinaraea sp., Goniopora
stutchburyi and a solitary,
juvenile Turbinaria peltata
colony. The ahermatypic cup coral
Balanophyllia sp. was recorded but
noted as rare at this site. A number
of ghost nets were recorded within this survey site. |
P (shallow) |
-1 to -5 mPD |
This site was a
headland leading to a large beach. Seabed was composed of large boulders
leading to a sandy seabed at shallower depths near the beach. Several hard coral species were
recorded as common at this site: Oulastrea
crispata, Psammocora sp. and Goniopora stutchburyi. Other corals
recorded included: Porites lobata, Coscinaraea sp., Plesiastrea versipora and the ahermatypic cup coral Balanophyllia sp.. Gorgonians were rare with the odd Echinomuricea colony noted. Fouling and mobile invertebrates were
similar in composition with an abundant category designated to the large,
encrusting bryozoan Schizoporella
errata, Diadema setosum
(long-spined sea urchin) and Saccostrea
sp. (oysters). Also recorded at
this site were large mats of stalked zoanthids. A spot dive was also conducted at |
Q1 (shallow) |
-1 to -6.8 mPD |
This survey dive was the western side of
Yuen Kong Chau. Substratum
comprised of large and small boulders between 0-5 m gradually sloping to a
sand seabed (~6 m depth). The
upper shallows were predominated by encrusting corallines, turf algae,
barnacles, encrusting sponges and bryozoans. The lower shallows consisted of a
similar suite of sessile and mobile invertebrates as recorded for |
Q2 (shallow) |
-1 to -6 mPD |
This site encompassed the eastern side
of the Yuen Kong Chau islet. The site comprised vertical bedrock (at the
southern tip of the islet), and a mix of large and small boulders gradually
sloping to a sand/silt seabed.
Large barnacles, encrusting bryozoans and sponges predominated. Also recorded were oysters,
and sea urchins including Diadema
setosum and Anthocidaris
crassispina. Isolated and
small hard coral colonies were recorded and included: Psammocora sp., Goniopora
stutchburyi (common), the faviids Oulastrea
crispata, Cyphastrea sp. and Favites abdita, Coscinaraea sp. and the ahermatypic Balanophyllia sp.. |
R1 (shallow) |
-2 to -8 mPD |
These survey areas were comprised of a
mix of large and small boulders with scattered, small sand patches gradually sloping
to a silt seabed. A total of
seven hard coral species were recorded and matched those recorded from South
Soko and Yuen Kong Chau with predominant species such as Psammocora sp., Goniopora
stutchburyi , Oulastrea crispata
and the ahermatypic Balanophyllia
sp.. Octocorals were recorded
from R1 and R5 only. R1 possessed
numerous small gorgonian colonies of Echinomuricea,
unusual for such shallow depths, however, the
majority of these colonies exhibited high partial and total mortality. R5 contained a few Dendronephthya and Euplexaura colonies on the eastern
side of the channel. The sessile
benthos was predominated by encrusting bryozoans such as Schizoporella errata, encrusting sponges, oysters, spiral tube
worms, mussels (Perna viridis),
jewel anemones and thick layers of encrusting masses of tube worms together
with sponges and bryozoans.
Coralline algae were encrusted on all boulder surfaces in the upper
shallows. |
R2 (shallow) |
-2 to -8 mPD |
|
R5 (shallow) |
-4 to -7 mPD |
|
R3 (deep) |
- 8 to -10 mPD |
Tau Lo Chau was the only location during
2005 surveys were dive conditions permitted REA surveys in the deep depth
range of 6-10 m. Two surveys were
conducted along the southwestern section of Tau Lo Chau and were comprised of
large and small silt ladened boulders.
These two survey sites possessed an atypical abundance of large,
mature gorgonians (whips and fans) and large ahermatypic cup corals (Tubastrea/ Dendrophyllia sp.).
Gorgonians identified were of the genera Euplexaura, Echinomuricea
and Echinogorgia. There was a
notable absence of other sessile or mobile invertebrates except for numerous
hydroids and low records of encrusting sponges and bryozoans. With the exception of the cup corals
no other hard coral species were recorded. Also of note was the number of
gorgonian colonies with commensal anemones attached. |
R4 (deep) |
- 7 to -10 mPD |
|
|
|
|
Table 9.12 Seabed
Attributes Along the Survey Transects at
|
A |
A |
B |
B |
C |
C |
D |
D |
E1 |
E1 |
E2 |
E2 |
E3 |
E3 |
E4 |
E4 |
I |
J |
K |
L |
M |
N |
O |
P |
Q1 |
Q2 |
R1 |
R2 |
R3 |
R4 |
R5 |
Transect depth
(b) |
s |
d |
s |
d |
s |
d |
s |
d |
s |
d |
s |
d |
s |
d |
s |
d |
s |
s |
s |
s |
s |
s |
s |
s |
s |
s |
s |
s |
d |
d |
s |
Seabed
attributes (a) |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Hard substrate |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Continuous pavement |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Bedrock |
4 |
1 |
|
|
|
|
1 |
|
1 |
|
1 |
|
3 |
|
3 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Rubble |
|
1 |
1 |
|
1 |
|
1 |
|
1 |
1 |
1 |
1 |
|
1 |
|
1 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Sand |
1 |
2 |
2 |
2 |
2 |
|
3 |
|
1 |
|
1 |
4 |
|
4 |
1 |
2 |
|
|
|
1 |
|
|
3 |
3 |
3 |
2 |
2 |
2 |
2 |
3 |
2 |
Silt |
|
|
|
4 |
1 |
5 |
|
5 |
|
4 |
|
|
|
|
|
|
|
|
|
|
|
2 |
2 |
|
|
|
|
|
2 |
2 |
|
Boulders – large |
|
1 |
3 |
|
2 |
|
1 |
|
2 |
|
4 |
1 |
2 |
1 |
2 |
2 |
6 |
6 |
5 |
5 |
6 |
6 |
|
5 |
4 |
4 |
4 |
4 |
4 |
|
5 |
Boulders – small |
|
1 |
1 |
|
1 |
|
|
|
2 |
|
1 |
1 |
1 |
1 |
|
1 |
|
|
3 |
|
|
|
5 |
|
3 |
2 |
|
3 |
3 |
4 |
2 |
Ecological attributes (b) |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Hard coral |
|
|
|
|
1 |
|
|
|
|
|
|
1 |
1 |
1 |
|
|
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
Dead standing coral |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
1 |
1 |
1 |
1 |
1 |
|
1 |
1 |
1 |
1 |
1 |
|
|
1 |
|
Soft coral |
1 |
1 |
1 |
|
|
|
|
|
|
|
|
|
1 |
2 |
1 |
2 |
1 |
1 |
1 |
1 |
|
1 |
|
1 |
1 |
2 |
1 |
1 |
2 |
3 |
1 |
Antipatharia |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Macroalgae |
1 |
|
2 |
|
2 |
|
1 |
|
4 |
|
1 |
|
|
|
|
2 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Notes: (a) 1=<5%
Cover, 2= 6-10% Cover, 3 = 11-30% Cover, 4 = 31-50% Cover, 5 = 51-75% Cover, 6
= 76-100% Cover.
(b) A to
E = transect line; s= shallow water; d=deep water
Table
9.13 Coral
Species Recorded Along the Survey Transects at
|
A |
B |
C |
D |
E1 |
E2 |
E3 |
E4 |
I |
J |
K |
L |
M |
N |
O |
P |
Q1 |
Q2 |
R1 |
R2 |
R5 |
R3 |
R4 |
Hard
Coral Species (a) |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Porites
lobata |
0 |
0 |
0 |
0 |
0 |
1 |
0 |
0 |
0 |
1 |
1 |
0 |
0 |
0 |
0 |
2 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
Psammocora
spp. |
0 |
0 |
0 |
0 |
0 |
1 |
0 |
0 |
1 |
1 |
2 |
2 |
2 |
3 |
2 |
3 |
2 |
3 |
1 |
0 |
2 |
0 |
0 |
Coscinarea sp. |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
1 |
1 |
0 |
2 |
0 |
2 |
2 |
0 |
1 |
0 |
0 |
0 |
0 |
0 |
Pseudosideratrea tayami |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
3 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
Turbinaria
peltata |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
1 |
0 |
2 |
2 |
0 |
0 |
0 |
2 |
2 |
Balanophyllia sp. |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
3 |
2 |
3 |
3 |
3 |
3 |
2 |
2 |
3 |
2 |
2 |
3 |
0 |
3 |
3 |
Favites
abdita |
0 |
0 |
0 |
0 |
0 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
1 |
0 |
0 |
0 |
0 |
0 |
Plesiastrea
versipora |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
2 |
0 |
2 |
0 |
0 |
0 |
0 |
2 |
0 |
0 |
Leptastrea pruinosa |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
1 |
0 |
2 |
3 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
Cyphastrea sp. |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
2 |
2 |
0 |
0 |
2 |
0 |
0 |
2 |
0 |
0 |
Echinophyllia sp |
0 |
0 |
0 |
0 |
0 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
Goniopora
stutchburyi |
0 |
0 |
0 |
0 |
0 |
1 |
0 |
0 |
0 |
0 |
0 |
1 |
2 |
0 |
2 |
3 |
2 |
3 |
2 |
2 |
0 |
0 |
0 |
Goniopora
lobata |
0 |
0 |
0 |
0 |
0 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
Oulastrea
crispata |
0 |
0 |
1 |
0 |
0 |
1 |
0 |
0 |
2 |
2 |
2 |
3 |
3 |
0 |
2 |
3 |
2 |
2 |
3 |
3 |
0 |
0 |
0 |
Tubastrea sp. / Dendronophyllia sp. |
0 |
0 |
0 |
0 |
0 |
0 |
1 |
0 |
2 |
2 |
2 |
2 |
2 |
2 |
0 |
0 |
2 |
2 |
0 |
0 |
0 |
2 |
2 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Octocoral
Species (a) |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Dendronephthya
sp. |
0 |
0 |
0 |
0 |
0 |
0 |
1 |
1 |
1 |
0 |
0 |
0 |
0 |
2 |
0 |
0 |
0 |
2 |
0 |
0 |
2 |
2 |
0 |
Euplexeura sp. |
1 |
1 |
0 |
0 |
0 |
0 |
1 |
1 |
2 |
1 |
0 |
0 |
0 |
2 |
0 |
0 |
0 |
0 |
1 |
0 |
0 |
3 |
3 |
Echinomuricea sp. |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
1 |
0 |
1 |
0 |
2 |
0 |
1 |
2 |
1 |
3 |
0 |
0 |
3 |
3 |
Echinogorgia sp. |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
3 |
3 |
Note: (a).
0=absent, 1=rare, 2=uncommon, 3=common, 4=abundant, 5=dominant
Also note Sites F and G were surveyed by spot dive so that
REA data were not collected for these sites.
IMPORTANT
The ranks shown in the Table above indicate the relative
abundance of each coral in relation to other corals in the community. In other
words, these broad categories rank taxa in terms of relative abundance of
individuals, rather than the contribution to benthic cover along each
transect. The ranks are subjective
assessments of abundance, rather than quantitative counts of each taxon. For
instance, if a coral is ranked as ‘common’, it means it was more frequent than
other coral species along the transect. It should be borne in mind that coral
cover along all of the transects where corals occurred
was very low (<5% cover).
9.3.11
Comparison of South Soko Subtidal Hard
Surface Habitats With Other
Coral coverage at
Previous studies and surveys ([50])
([51]) ([52])
have shown that live coral cover in
Figure
9.11 Comparison of
Number Coral Species recorded at Other Sites in
Figure 9.12 Comparison of Percentage Live Coral Cover at Other Sites
in
As can be seen from Figure 9.12
coral cover at South Soko is very sparse (<3% cover) in relation to coral
sites further to the east of Hong Kong such as the Ninepins where, for
instance, 23.1% live coral cover was reported.
Higher coral cover than South Soko was also previously recorded at the
Penny’s Bay Site (8.99% cover) at
9.3.12
Epifaunal and Infaunal Assemblages
(Benthos)
Survey Methodology
Sampling Locations
Benthic samples were collected at four sites representative of subtidal
soft bottom habitats in the vicinity of the proposed LNG terminal at
·
·
Southern
·
Adamasta
Channel (AC)
·
Peaked
·
Tai O
(TO)
·
Lung
Kwu Chau and
·
·
Black
Point (BP1 and BP2)
The locations of each survey site are shown in Figure 9.13.
Field Sampling
Methodology
At each survey site, six stations approximately 50 m apart were
established and one grab sample was collected from each station. Stations were sampled using a modified
Van Veen grab sampler (960 cm2 sampling area; 11,000 cm3 capacity) with a
supporting frame attached to a swivelling hydraulic winch cable.
Sediment from the grab samples were sieved on board the survey
vessel. The sediments were washed
onto a sieve stack (comprising 1 mm and 500 (m meshes) and gently rinsed with
seawater to remove all fine material.
Material remaining on the two screens following rinsing was combined and
carefully rinsed using a minimal volume of seawater into pre-labelled thick
triple-bagged ziplock plastic bags.
A 20% solution of buffered formalin containing Rose Bengal in seawater
was then added to the bag to ensure tissue preservation. Samples were sealed in plastic
containers for shipment to the taxonomy laboratory for sorting and identification.
Laboratory Techniques
The benthic laboratory performed sample re-screening after the samples
had been held in formalin for a minimum of 24 hours to ensure adequate fixation
of the organisms. Individual
samples from the 500 mm and 1 mm2 mesh sieves were gently rinsed with fresh
water into a 250 mm sieve to remove the formalin from the sediments. Sieves were partially filled while
rinsing a specific sample to maximize washing efficiency and prevent loss of
material. All material retained on the
sieve was placed in a labelled plastic jar, covered with 70% ethanol, and
lightly agitated to ensure complete mixing of the alcohol with the
sediments. Original labels were
retained with the re-screened sample material.
Standard and accepted techniques were used for sorting organisms from
the sediments. Small fractions of a
sample were placed in a petri dish under a 10-power magnification dissecting
microscope and scanned systematically with all animals and fragments removed
using forceps. Each petri dish was
sorted at least twice to ensure removal of all animals. Organisms representing major taxonomic
groups including Polychaeta, Arthropoda, Mollusca, and miscellaneous taxa were
sorted into separate, labelled vials containing 70% ethanol.
Taxonomic identifications were performed using stereo dissecting and
high-power compound microscopes.
These were generally to the family level except for dominant taxa, which
were identified to species. The
careful sampling procedure employed minimizes fragmentation of organisms. If breakage of soft-bodied organisms
occurs, only anterior portions of fragments were counted, although all
fragments were retained and weighed for biomass determinations (wet weight).
Results of Benthic Surveys
Survey Dates and Conditions
Grab samples were collected from sites off the north, east and west
coasts of South Soko (SK1 to SK4) as well as along the proposed pipeline
alignment (AC PH, TO, MP1, MP2, UR, BP1 and BP2) in both the dry (25-26th
February 2004 and 8th November 2004) and wet (5-6th July 2004 and 9th September
2004). Additional surveys to
collect grab samples from sites off the southern side of
Dry Season Survey
Results
A total of 4,309 individual organisms were collected from the 96 grab
sampling stations in the vicinity of the
A breakdown of dry season 2004 benthic data by site revealed relatively
large differences in terms of number of individuals, biomass and taxonomic
richness (here represented by number of families of infaunal organisms). The South Soko Island site SK3 recorded
the highest number of individuals with mean of 161 individuals station-1 (±
279.9 SD) recorded, equating to 1613.7 m-2 (± 2946.2 SD) (Table 9.14Table 9.14). In
comparison, Tai O (TO) and the Sha Chau and
Table 9.14 Grab
Sample Composition (Infaunal Assemblages) of Each Sample Site for the Soft Bottom
Habitat Surveys at
Site |
Number of Stations Sampled |
Total Number of Infaunal Individuals |
Mean Number of Individuals Station-1
(±SD) |
Mean Number of Individuals m-2 (±SD) |
Total Biomass (g wet weight) |
Mean Taxonomic Richness (No. Families)
Station-1 (±SD) |
Mean Taxonomic Richness (No. Genera)
Station-1 (±SD) |
Mean Biomass Individual-1
(g wet weight) |
SK1 |
6 |
465 |
77.5 (± 50.7) |
806.0 (± 527.0) |
27.0 |
14.8 (± 4.9) |
16.2 (± 5.2) |
0.06 |
SK2 |
6 |
120 |
20.0 (± 4.9) |
208.0 (± 50.5) |
11.4 |
9.8 (± 2.9) |
10.7 (± 2.7) |
0.09 |
SK3 |
6 |
931 |
161 (± 279.9) |
1613.7 (± 2946.2) |
82.8 |
10.5 (± 4.3) |
11.3 (± 4.4) |
0.09 |
SK4 |
6 |
306 |
51 (± 40.2) |
530.4 (± 418.2) |
26.7 |
14.8 (± 4.40) |
16.5 (± 5.28) |
0.09 |
SSK1 |
6 |
198 |
33.0 (± 8.8) |
343.8 (± 92.0) |
14.9 |
13.8 (± 1.5) |
13.8 (± 1.5) |
0.08 |
SSK2 |
6 |
94 |
15.7 (± 4.4) |
163.2 (± 46.0) |
5.5 |
9.7 (± 2.7) |
9.7 (± 2.7) |
0.05 |
SSK3 |
6 |
213 |
35.5 (± 27.0) |
369.8 (± 281.0) |
89.3 |
12.7 (± 4.5) |
12.7 (± 4.5) |
0.04 |
SSK4 |
6 |
175 |
29.1 (± 14.2) |
303.8 (± 147.8) |
89.4 |
14.0 (± 2.7) |
14.0 (± 2.7) |
0.05 |
AC |
6 |
624 |
104.0 (± 61.0) |
1081.6 (± 644.8) |
130.7 |
12.2 (± 4.7) |
13.2 (± 5.6) |
0.21 |
PH |
6 |
255 |
42.5 (± 16.4) |
442.0 (± 170.5) |
6.1 |
6.2 (±1.9) |
6.7 (± 1.6) |
0.02 |
TO |
6 |
78 |
13.0 (± 4.0) |
135.2 (± 41.6) |
7.2 |
8.3 (± 1.9) |
8.7 (± 2.2) |
0.09 |
MP1 |
6 |
90 |
15.0 (± 6.2) |
156.0 (± 64.8) |
9.9 |
7.2 (± 3.3) |
7.5 (± 4.0) |
0.11 |
MP2 |
6 |
86 |
14.3 (± 12.8) |
149.1 (± 133.1) |
12.8 |
6.2 (± 5.0) |
6.7 (± 5.0) |
0.15 |
|
6 |
91 |
15.2 (± 13.7) |
157.7 (± 142.8) |
8.2 |
5.5(± 3.5) |
5.8 (± 3.8) |
0.09 |
BP1 |
6 |
203 |
33.8 (± 39.3) |
351.9 (± 408.7) |
56.9 |
6.7 (± 4.1) |
6.8 (± 4.4) |
0.28 |
BP2 |
6 |
380 |
63.3 (± 47.8) |
658.7 (± 497.1) |
25.2 |
11.0 (± 5.8) |
12.0 (± 6.1) |
0.07 |
The highest biomass in the dry season 2004 was recorded at the Adamasta
Channel (AC) site, with 130.7g wet weight (Table
9.12). Two south
Overall, the majority (67.8%) of the numbers of infaunal organisms
recorded during the dry season surveys were from the Phyla Annelida. The
remainder were Mollusca (18.1%), Arthropoda (4.5%), Echinodermata (3.8%),
Sipuncula (3.0%) and Echuira (2.8%).
.
The polychaete worm Prionospio
queenslandica from the family Spionidae, was the
most abundant species from the surveys, particularly at the Black Point (BP1
and BP2), South Soko (SK1) and Adamasta Channel (AC) sites. No rare or uncommon species of infauna
were recorded in the dry season 2004 survey at
The composition of the infauna at each site in terms of numerical
abundance of organisms present (grouped by class) in the dry season surveys, is
presented in Figure 9.14. The majority of organisms collected were
clams from the class Bivalva, owing to the high number encountered at the South
Soko (SK3) site. By comparison,
numbers of bivalves at other sites were low so that overall Polychaetes were
typically the dominant group at each site in terms of the numbers of
individuals present.
Figure
9.14 Mean Numbers
of Individuals per Station of Infaunal Organisms (Class level) from Benthic
Samples collected at
The composition of infaunal assemblages at
each site in terms of mean biomass of groups of organisms (by class) at each
site is presented in Figure 9.15. The highest distribution of biomass was
from Echiurida in the Adamasta Channel (AC). Other sites with generally higher levels
of biomass include Echinoidea at the south South Soko SSK4 site, bivalva at the
South Soko SK3 and south South Soko SSK3 sites, and Holothuroidea at Black
Point (BP1).
Figure 9.15 Mean Biomass Station-1 Infaunal Organisms (Class level) from
Benthic Samples collected at
Wet Season Survey Results
A total of 6,351 individual organisms were
collected from the 96 grab sampling stations in vicinity of
A breakdown of wet season 2004 benthic
data by site revealed relatively large difference in terms of number of
individuals, biomass and taxonomic richness (here represented by number of
families of infaunal organisms).
The Urmston Road (UR) recorded the highest number of individuals with
mean of 498.8 individuals station-1 (± 997.3 SD) recorded, equating to 5,188 m-2 (± 10,372.3 SD) (Table 9.15). By
comparison, Southern South Soko (SSK2), Tai O (TO) and the Sha Chau and Lung
Kwu Chau Marine Park (MP1 and MP2) recorded the lowest mean numbers of
individuals (13.5 (± 7.1), 12.7 (± 2.5 SD), 10.3 (± 4.4 SD) and 9.3 (± 7.3 SD)
individuals station-1, respectively).
As can be seen from the standard deviation at each site, the numbers
varied greatly between stations, particularly at those sites with high numbers
of individuals (
Table 9.15 Grab
Sample Composition (Infaunal Assemblages) of Each Sample Site for the Soft
Bottom Habitat Surveys at
Site |
Number of Stations Sampled |
Total Number of Infaunal Individuals |
Mean Number of Individuals Station-1
(±SD) |
Mean Number of Individuals m-2 (±SD) |
Total Biomass (g wet weight) |
Mean Taxonomic Richness (No. Families)
Station-1 (±SD) |
Mean Taxonomic Richness (No. Genera) Station-1
(±SD) |
Mean Biomass Individual-1
(g wet weight) |
SK1 |
6 |
149 |
24.8 (± 20.1) |
258.3 (± 230.0) |
50.4 |
11.2 (± 4.3) |
11.3 (± 4.5) |
0.34 |
SK2 |
6 |
88 |
14.7 (± 8.8) |
152.5 (± 91.1) |
122.6 |
7.2 (± 3.7) |
7.2 (± 3.7) |
1.39 |
SK3 |
6 |
822 |
137.0 (± 205.4) |
1,424.8(± 2,136.3) |
78.6 |
16.5 (± 4.2) |
17.2 (± 4.0) |
0.10 |
SK4 |
6 |
147 |
24.5 (± 19.3) |
254.8 (± 201.2) |
31.2 |
12.2 (± 5.04) |
12.8 (± 5.71) |
0.21 |
SSK1 |
6 |
211 |
35.2 (± 16.4) |
366.3 (± 171.2) |
35.5 |
11.3 (± 3.4 |
11.3 (± 3.4) |
0.17 |
SSK2 |
6 |
81 |
13.5 (± 7.1) |
140.6 (± 74.1) |
36.8 |
8.7 (± 3.8) |
8.7 (± 3.8) |
0.45 |
SSK3 |
6 |
387 |
64.5 (± 56.6) |
671.9 (± 589.4) |
144.6 |
13.3 (± 3.8) |
13.3 (± 3.8) |
0.37 |
SSK4 |
6 |
240 |
40.0 (± 9.5) |
416.7 (± 98.8) |
53.6 |
12.0 (± 3.3) |
12.0 (± 3.3) |
0.22 |
AC |
6 |
337 |
56.1 (± 21.2) |
584.1 (± 220.8) |
22.7 |
11.2 (± 3.7) |
12.2 (± 4.1) |
0.07 |
PH |
6 |
133 |
22.2 (± 16.0) |
230.5 (± 165.9) |
2.92 |
5.5 (± 2.5) |
5.7 (± 2.7) |
0.02 |
TO |
6 |
76 |
12.7 (± 2.5) |
131.7 (± 26.0) |
50.4 |
12.2 (± 5.0) |
12.8 (± 5.7) |
0.13 |
MP1 |
6 |
62 |
10.3 (± 4.4) |
107.5 (± 45.9) |
33.2 |
5.5 (± 2.1) |
5.5 (± 2.1) |
0.53 |
MP2 |
6 |
56 |
9.3 (± 7.3) |
97.1 (± 75.8) |
9.32 |
4.5 (± 1.9) |
5.0 (± 2.3) |
0.17 |
|
6 |
2,993 |
499.0 (± 997.0) |
5,187.9 (± 10,372.3) |
174.5 |
7.0 (± 5.4) |
7.3 (± 5.8) |
0.06 |
BP1 |
6 |
335 |
55.8 (± 38.1) |
580.7 (± 396.2) |
161.4 |
10.0 (± 3.7) |
10.8 (± 4.6) |
0.48 |
BP2 |
6 |
234 |
39.0 (± 24.1) |
405.6 (± 250.7) |
376.6 |
8.0 (± 2.8) |
8.5 (± 2.6) |
1.61 |
|
|
|
|
|
|
|
|
|
The highest
biomass recorded from the wet season surveys was at the Black Point (BP2) site,
with 376.6 g wet weight. The Black
Point Station (BP1), Southern South Soko (SSK3), South Soko Island (SK2) and
Urmston Road (UR) also recorded comparatively high biomass in contrast to the
other sites surveyed, with a total biomass of 161.4,
144.6, 122.6 and 174.5 g wet weight, respectively.
South
Soko Island sites SK3, SK4 and SSK3 recorded the highest diversity, in terms of
numbers of families, in the wet season 2004, with a mean number of 16.5 (± 4.23
SD), 12.2 (± 5.04 SD) and 13.3 (± 3.8) respectively, and, in terms of numbers of genera, the highest diversity in the
wet season was also recorded at those sites with a mean number of 17.2 (± 3.97
SD), 12.8 (± 5.71 SD) and 13.3 (± 3.8) genera station-1 respectively.
Overall,
the majority (68.7%) of infaunal organisms recorded during the wet season were
from the Phyla Annelida. The remainder were Arthropoda (15.0%), Echinodermata
(7.2%), Mollusca (4.9%), Sipuncula (3.9%), Echiura (0.2%) and Platyhelminthes
(0.1%).
The
polychaete worm Prionospio queenslandica
from the family Spionidae, was the most abundant
species from the wet season surveys.
This species was recorded in highest numbers at the Black Point (BP1 and
BP2) and Adamasta Channel (AC) sites.
No rare or uncommon species of infauna were recorded at
The
composition of infaunal organisms (grouped by class) at each site in terms of
mean number of individuals recorded during the wet season 2004 and 2005
surveys, is presented in Figure 9.16. At most sites, the Polychaeta marine
worms were the dominant group in terms of mean number of individuals recorded.
At Urmston Road (UR) and South Soko SK3 sites, much higher numbers of clams
(from the class Bivalva) were found.
The
composition of infauna at each site in terms of mean biomass grouped at class
level is presented in Figure 9.17.
Although animals such as the Polychaeta tended to be most numerically abundant,
the larger-bodied animals from the Bivalva and Echinoidea groups made large
contributions to biomass at sites such as Black Point (BP1 and BP2), Urmston
Road (UR) and south South Soko (SSK3).
Figure 9.16 Mean
numbers of Individuals per Station of Infaunal Organisms (Class level) from
Benthic Samples collected at
Figure 9.17 Mean Biomass station-1 Infaunal Organisms (Class level) from
Benthic Samples collected at
Amphioxus
Besides
infaunal organisms, grab samples contained some epifauna that live close to or
on the surface of the seabed. Among
these, there was a notable record of the amphioxus species Branchiostoma belcheri found at the eastern facing bay, Tung Wan
(Site SK3). In
Branchiostoma belcheri is mobile animal that can freely swim
through the water but typically burrows in sand during feeding. Although there are
few publications on this eel-like animal’s ecology, in terms of habitat
preference, it has been reported that it prefers sandy seabed areas with a
depth of - 8 to 15 m which have comparatively clear and saline waters ([59]). The species has a wide distribution and
been recorded around the region including China, Taiwan, Japan, Phillipines,
Thailand, Northern Australia as well as further a field in India, Madagascar
and East Africa. It was recently
recorded from several sampling sites across eastern Hong Kong waters from Tai
Long Wan, Long Ke Wan, Sai Kung to Ninepins and the Tathong Channel ([60]). Except at Tai Long Wan, only one or two
individuals were recorded from these locations. ERM also reported this species off
The
site with the highest abundance of this species in Hong Kong is Tai Long Wan in
the northeast
9.3.13
Comparison of South Soko Benthic Fauna With Other Sites in
A
comparison with similar sites in Hong Kong puts the ecological value of the
study site in perspective with the ecology of the surrounding area and also other
sites that may share the same physical attributes such as outlying islands
around
As
can be seen from Figure 9.18 the
benthic biomass of comparable areas in
The
biomass of the infaunal communities found at
Figure 9.18 Comparison of Mean Biomass of Benthic
communities around
The
species diversity of the benthic community along the corridor of the proposed
submarine natural gas pipeline (AC, PH, TO, MP1, MP2, UR, BP1 and BP2) was
similar to most locations in Hong Kong ([68]).
The number of species of the benthic organisms along
the corridor of the proposed submarine natural gas pipeline were
recorded in the range of 15 to 33 species per 0.576 m2 during wet season and 19
to 35 species per 0.576 m2 during dry season. In comparison, the mean number of
species of the 120 stations surveyed by CityU ([69]) were 32.9 per 0.5 m2 (wet season) and
33.7 per 0.5 m2 (dry season) respectively.
The
species diversity of the benthic community at the proposed LNG terminal
(reclamation sites SK1 and SK3, and turning circle and approach channel SSK1,
SSK2 and SSK4) was comparatively higher than the
9.3.14
Marine Mammals
Methodology
Land-based Visual Survey
Land-based
visual surveys were conducted in the study area to qualitatively estimate
marine mammal use of habitats in the vicinity of
During the survey period, one of the
paired observers scanned the survey area continuously with Olympus 10 x 42
hand-held marine binoculars while the other used naked eye and occasional
binocular scans to identify, estimate group size, and study behaviour of the
any marine mammals observed in the study area. The role of observers rotated every 30
minutes. Each survey was 6 hours in
length. Survey times shifted to
record marine mammal activity during all possible daylight hours during the
survey period.
Monitoring surveys were conducted for five
days of each month. Surveys were
conducted monthly, commencing in February 2004, and lasting for a full calendar
year up to the end of January 2005.
Data Collected
The locations of all marine mammals
sighted within 2km of the sighting point were recorded on a data sheet (Table 16 of Annex 9-A). The
species and number of marine mammals, number of sightings and travelling paths
were recorded, together with observed behaviours at the times of sightings.
Whenever possible, the colour and spot pattern was also recorded. Due to the distances involved, the age
classes recorded during land-based visual survey can only be classified as
juvenile (unspotted calf or unspotted juvenile) or adult (mottled, speckled,
spotted adult and unspotted adult).
If fifteen minutes had passed with no sightings after an initial
sighting was made, any observed marine mammals were then considered to be a new
group or individual. As such, the
"sighting" data recorded represents first count data, or the location
where the marine mammals were first observed.
Distinguishing Features
The distinguishing features of the two
marine mammals observed during the surveys are as follows:
·
Indo-Pacific Humpback Dolphin (Sousa chinensis) -
Sousa chinensis is distinguished by
its wide-based, slightly falcate dorsal fin, located at mid-back. They have a long, slender rostrum, with a
shallow groove between the melon and the beak. Adults are up to 2.8 m long and are
white to pink in colour, and often have a variable degree of black spotting or
mottling.
·
Finless Porpoise (Neophocaena phocaenoides) - Neophocaena phocaenoides is
characterized by its lack of dorsal fin and the presence of a dorsal
ridge. It also has no beak. It is smaller in size than humpback
dolphins with an average body length
of much less than 2 metres. Adults
are commonly dark grey to black in colour.
Age Classes
Age class of humpback dolphins was identified in accordance with the
six age classes defined by Table 9.16.
Table 9.16 Age
Classes of Sousa chinensis
Age Class |
Body Length (m) |
Colour Pattern |
Spotted Pattern |
Behaviour |
Unspotted
Calf (UC) |
1
m to 1.3 m (approximately half length of adults); up to 6-8 months of age |
Uniform
black to dark grey |
No
spots |
Swim
dependently of adult, presumably the mother |
Unspotted
Juvenile (UJ) |
Approximately
1.5 m to 2 m (two-third of the adult length) |
Uniform
light grey |
No
spots |
Occur
in the vicinity of adults. |
Mottled
(MO) |
Approximately
similar length as SAs and UAs; 8.5 to 9 years old |
Light
pinkish grey |
Heaving
spotting |
Same
as SAs and UAs |
Speckled
(SP) |
With
same size as SAs and UAs |
Pale
pink to white |
Less
spotting pattern than MO |
Full
independence of movement and association; hard to distinguish from SA. |
Spotted
Adult (SA) |
Same
as UA |
Purely
pink to white |
Less
spotting pattern than MO or SP |
Same
as SP |
Unspotted
Adult (UA) |
Up
to 2.6 m |
Purely
pink to white |
Essentially
no spotting pattern but may have a few tiny spots |
Same
as SAs and SPs |
Only three classes, adult (include MO, SP,
SA and UA), juvenile (UJ) and calf (UC), can be identified during the
land-based visual survey due to the distant observation.
Age-determination study for finless
porpoise has been undertaken by tooth aging method, however, it cannot be
applied in the field ([71]). Growth of finless porpoise can be
classified into a number of age/sex classes ([72]). Neonates can be distinguished by
relatively large flippers, a shallow forehead, lighter colour than adults, a
very light patch around the lips and a gape-to-flipper stripe ([73]). Very young newborns may still show
prominent fetal folds. Meanwhile,
light grey skill colour with steeper forehead and prominent light lip patch are
still observed in juvenile stage ([74]). Adults are dark grey in colour.
Behaviour
Marine mammals exhibit certain behaviours
and for humpback dolphins this has been previously characterised ([75]) ([76]). These are presented in (Table 9.17Table 9.17).
Table 9.17 A
Summary and Description of Specific Types of Behaviour and Activities exhibited
by Indo-Pacific Humpback Dolphin Sousa chinensis
Type of Social Behaviours and
Activities |
Descriptions |
|
Activities |
|
|
Free
Travelling |
Directional
motion, Swimming fast, taking regular breaths on water surface. |
|
Feeding/Foraging |
Long
jumping and high-speed chasing while hunting fish; On sea surface, swimming slowly
rising intermittently before commencing the next dive. They may display certain behaviours
such as feeding rushes, fish whacking, carousels, and fluking dives. |
|
Boat
chasing/ Feeding behind trawlers |
Following
behind trawlers as a sign of feeding, they catch fish through the net or
escaping from it. |
|
Milling/Resting |
Remaining
in one area without any sign of feeding or social interaction; move slowly
with a drifting or gliding motion, rising slowly, or breathing while circling
over the same area. |
|
Socializing |
Extensive
bodily contact, inverted swimming, somersaulting, leaping and chasing with
aerial activity; group activities centred on animate or inanimate objects;
two to three individuals form a group. |
|
Spot Behaviour |
|
|
Breaching |
A
behavioural pattern also known as body slamming or a ‘log’ jump. The animal rises out of the water at
an angle between 90( to 45( to the sea surface. When exiting the water the dolphin’s flippers,
its abdomen or peduncle may clear the surface. |
|
Spyhopping |
Raising
the head vertically out of the water, then sinking
below the water without a splash.
Used to check an area for hazards. |
|
Tail
slapping |
The
act of slapping the tail against the sea surface. |
|
Porpoising |
Fast,
shallow, arching leaps with the dolphin coming either partially or entirely
out of the water. It was only
observed when the dolphins were boat chasing and allows the animals to combine
shallow dives for fish with a fast rate of travel. The adults will show noticeable colour
changes, turning from white to a deep pink. This is probably due to vascular
dilation in the blubber layer and is, possibly, a flush response to prevent
overheating. |
|
Nursing |
An
act of nursing a calf by a mother. |
|
Studies on behaviour of finless porpoise
are limited. Sightings are commonly
less prominent as the porpoise only bring their heads and their dorsal surface above
the water to breathe and the lack of dorsal fins makes them harder to
spot. Observed porpoise behaviour
is commonly simply feeding behaviour, such as “feeding circles” ([77]). Other feeding behaviours such as feeding
rushes with a sudden acceleration directly towards prey and fish chasing are
also common. Other observed
behaviour is similar to that observed in humpback dolphins, such as travelling and milling (refer to Table 9.17Table 9.17).
Site and Weather Conditions
Site conditions including sea state,
weather and visibility were also recorded along with any changes in
environmental conditions if they occurred during the duration of a survey. Surveys were only conducted under
acceptable sighting and weather conditions. Acceptable sighting conditions were
defined as days with sea state conditions of Beaufort 0 – 5, and visibility of
at least 2km from the observation point.
No surveys were conducted during unacceptable weather conditions, such
as during low visibility or during typhoons, thunderstorms or heavy rainstorm
warnings reported by the Hong Kong Observatory.
Vessel Based Visual
Survey
General Approach and Survey Subareas
Surveys were conducted in four
subareas. General characteristics
of the four survey subareas are listed in Table 9.18Table 9.18. Southwest Lantau (66 km2) represents a
new stratification of the South Lantau survey area, and this is the western
portion that includes the Fan Lau and the
Table 9.18 Summary of Characteristics of the
Four Survey Subareas in
Survey Area |
Area (km2) |
Effort (km) (1) |
Description |
|
30 (2) |
1,679 |
Very shallow enclosed bay with
extensive mudflats and mangroves; influenced by the |
|
38 |
530 |
Strong influence from |
|
28 |
3,094 |
Strong influence from Pearl River; narrow
strip along western border of Hong Kong; light development; dolphin watching
vessels at Tai O |
|
66 |
5,498 |
Seasonally influenced by the Pearl
River; very little development, but
includes major ferry lanes to |
Note: (1) Total survey effort conducted during this
study is presented here, but the survey effort (L) presented in Table 9.19 is only that used in
calculation of the abundance estimates (i.e., Beaufort 0-3 data).
(2) The total area of
The
The seasons were defined as follows:
Winter (December-February), Spring (March-May), Summer
(June-August), and Autumn (September-November). This is the same as in the long-term
study.
The survey transect lines were
presented in Figure
9.20.
Survey Methods
Vessel surveys were conducted from
two survey vessels, the King Dragon and the Tsun Wing (both ca. 12-15 m length,
with similar configuration), weather permitting (Beaufort 0-6, no heavy rain,
and visibility > 1,200 m).
However, only data collected in calm conditions of Beaufort 0-3 are
useable in calculating line transect estimates of density and abundance ([80])
([81]). The vessel had an open upper deck,
affording relatively unrestricted visibility. The observer team conducted searches and
observations from the flying bridge area, 4-5 m eye height above the water's
surface. Two observers made up the
on-effort survey team. As the
vessel transited the survey lines at a relatively constant speed of
approximately 15 km/hr, the primary observer searched for dolphins and
porpoises continuously through 7 X 50 Brunton marine binoculars. The data recorder searched with unaided
eye and filled-out the data sheets.
Both observers searched ahead of the vessel, between 270° and 90° (in
relation to the bow, which is defined as 0°). On most surveys, there were three
observers, and one auditor.
Observers rotated positions after
approximately 30 minutes of effort, to give them a rest after each hour of
search effort, thereby minimizing fatigue.
Observers had undergone a 3-day training program before the start of
data collection, which included detailed classroom instruction and a day of
at-sea training. Only two species
of small cetaceans regularly occur in
Effort data collected during
on-effort survey periods included time and position for the start and end of
search effort, vessel speed, sea state (Beaufort
scale), visibility, and distance travelled in each series (a continuous period
of search effort). When dolphins or
porpoises were sighted, the data recorder filled out a sighting sheet, and
generally the team was taken off-effort and the vessel diverted from its course
to approach the dolphin group for group size estimation, assessment of group
composition, behavioural observations, and collection of identification photos. The sighting sheet included information
on initial sighting angle and distance, position of initial sighting, sea
state, group size and composition, and behaviour, such as response to the
survey vessel and associations with fishing vessels (Tables 18 and 19 of Annex 9-A). Position, distance travelled, and vessel
speed were obtained from a hand-held Global Positioning System (a Garmin Gecko
GPS unit).
Observers were trained and
calibrated in distance estimation, by asking them to make distance estimates to
various objects (e.g., other boats, specific points on shore, floating debris,
etc.). Simultaneously, a distance
reading was taken with a laser rangefinder (Leica 800 or Bushnell Yardage Pro
800 model). Plots of measured vs.
estimated distance were shown to observers occasionally, so they could see if
they needed to refine their distance estimates. This procedure resulted in increased
accuracy of observer distance estimates, and previous efforts have shown that
significant bias is not caused by the remaining inaccuracy in distance
estimation ([84])([85])([86]).
When dolphins were sighted, the
observers typically went off-effort and the vessel approached the dolphin group
for accurate estimation of group size/composition and for
photo-identification. Photographs
were taken with Canon 35-mm SLR autofocus cameras (EOS 20D digital model). Cameras were equipped with digital data
recorders and date and time were associated with each frame, allowing it to be
correlated with a particular sighting.
The primary lens used was a Canon L series 300 mm / f4.0 image
stabilizer telephoto. Usually, the
lens was used with a 1.4X teleconverter, thereby increasing its effective focal
length. Images were shot at the highest available resolution (8.2 megapixels)
and stored on Compact Flash cards (mostly 1.0 GB).
For photo-identification, generally,
dolphin groups were approached slowly from the side and behind ([87]). Manoeuvring the boat to within 15-40 m,
directly alongside a moving group of dolphins resulted in the best shots. Every attempt was made to photograph
each dolphin in the group, even those that appeared to have no unique
markings. If possible, both sides
of the dolphins were photographed, since the coloration markings are not
completely symmetrical.
Data Analysis Methods
Line Transect Analysis
One day’s survey effort was used as
the sample for analyses. For
estimation of density and abundance, only surveys with at least 2.0 km of
useable effort were included.
Estimates were calculated from sighting and effort data collected during
conditions of Beaufort 0-3 ([88])([89])([90]), using line transect methods ([91]). The estimates were made using the
computer program DISTANCE Version 2.2 ([92]). The following formulae were used
to estimate density, abundance, and their associated coefficient of variation:
where D = density (of individuals),
n
= number of on-effort sightings,
f(0)
= trackline probability density at zero distance,
E(s)
= unbiased estimate of average group size,
L
= length of transect lines surveyed on effort,
g(0)
= trackline detection probability,
N
= abundance,
A
= size of the survey area,
CV
= coefficient of variation, and
var
= variance.
For the
Northwest Lantau area, because the current study did not survey the entire
survey area used in the long-term study, individual encounter rates for each
season were calculated as a basis for comparison. This is largely equivalent to
calculating densities, but it does not explicitly take into account variations
in sightability of the dolphins.
However, despite this, it provides a useful basis for comparison with
future surveys. The encounter rates
were calculated by dividing the number of individual dolphins observed on a
particular day by the amount of effort conducted on that day. Seasonal averages and their standard deviations
were then computed. Only data
collected during Beaufort 0-3 conditions were used for this.
Pooling and Stratification
Strategies
A strategy of selective pooling and
stratification was used, in order to minimize bias and maximize precision in making
the estimates of density and abundance ([93]). Data from the long-term database (most
research funded by AFCD) were pooled with data from the present study to
increase sample sizes and improve the robustness of the analyses. This strategy can be applied directly to
the
Sighting Rate [n/L] - Sighting rate varies strongly with
season and area ([94])([95]), and thus a fully-stratified
analysis (full stratification by both season and survey area) was used. Clearly, sighting rate is one of the major
parameters affecting density and abundance estimates, and although sample sizes
were small for some strata (n < 5), pooling was not justified.
Trackline Probability Density [f(0)]
-
Because biases associated with small sample sizes can strongly affect the
accuracy of density and abundance estimates, Buckland et al.'s (2001) ([96]) guidelines regarding minimal sample
sizes for estimation of the trackline probability density were followed. They suggested a minimum sample size of
60 sightings for modeling of this parameter. Several mathematical models were fitted
to the data (hazard-rate, half-normal, and uniform), and the model with the
lowest value of the Akaike’s Information Criterion was automatically chosen by
DISTANCE for estimation of f(0). Because most seasons within a phase did
not have adequate numbers of sightings, all the data (from all four seasons and
the three main survey subareas) were pooled to calculate a single humpback
dolphin trackline probability density, and then used this in all the estimates
of density and abundance. This
strategy ensured sample sizes of > 100 for humpback dolphins.
For
finless porpoises, although only 29 sightings were made in the LNG study, the
post-stratification of the South Lantau long-term data into Southeast and
Average Group Size [E(s)] - Because of indications that group
size varies by geographic region and season ([97])([98]), a fully-stratified analysis was
used. DISTANCE computed both the
arithmetic mean and a size-bias corrected mean; the lesser of these two values
was used in the calculations (in order to avoid size-bias generally caused by missing
smaller groups at large perpendicular distances).
Trackline Detection Probability
[g(0)] - For
Hong Kong humpback dolphins, Jefferson (2000) ([99]) reported group dive time data and
collected 71.8 hours of independent observer data, and from this estimated that
the detection probability is unity for that study. The present study was an extension of
For finless porpoises, the estimate
of g(0) presented by Jefferson et al. (2002) ([101]), which was calculated from data collected
with a Porpoise Detector (POD), was used.
This device collects data on the occurrence of acoustic clicks made by
porpoises. The value of the
estimate was 0.72.
Coefficient of Variation [CV] – The variance component for the
appropriate estimate of each component of the line transect
equation was used in calculating the overall CV of the estimated density and abundance
(see formula above). This resulted
in more precise estimates for some areas and seasons than would have been the
case with a fully-stratified analysis.
However, this came at the expense of some slight potential for increase
in bias.
Photo-identification and
Age Class Composition
Photographs of dolphins taken during
surveys were first examined and sorted into those that contained a potentially
identifiable individual. Then,
those photos were again examined in detail and any identifiable individuals
were compared to the photo-ID catalog accumulated over the last 10+ years of
dolphin research in
Observers attempted to classify the
dolphins observed into the six age classes identified in the long-term study on
humpback dolphins in Table 9.16). However, many animals were not seen at
close enough range to place them into an age class, and therefore only data on
groups from which the age class composition of the entire group was determined
was analyzed.
Grid Analysis of Habitat Use
For the quantitative grid analysis
of habitat use of humpback dolphins and finless porpoises, positions of
on-effort sightings were plotted onto 1 km2 grids within the four survey
subareas. Sighting densities (number
of on-effort sightings per km2) were calculated for each grid. Sighting density grids were then further
normalized with the amount of survey effort conducted within each grid. The survey effort spent in each grid for
each survey day was examined in detail (i.e., when the survey boat traversed
through a specific grid once, one unit of survey effort was counted for that
grid), and then the amount of survey effort per grid was calculated for all
sighting density grids. After
normalizing the original sighting density grids by survey effort, sighting
density data were generated. The
new density unit is termed “SPSE”, representing the number of on-effort
sightings per unit of survey effort.
This sighting density information, was further
elaborated to look at actual dolphin / porpoise densities (exact number of
dolphins or porpoises from on-effort sightings per km2). The new unit was termed “DPSE”, which is
the number of individual dolphins / porpoises per unit of survey effort. Plotting the DPSE values of surveyed
grid squares on maps allows areas where the most dense
sightings of dolphins and porpoises occur to be identified.
Ranging Pattern Analysis
Location data were obtained from the
long-term sighting database and photoidentification catalog, and only those
individuals sighted ten times or more were included for analysis of individual
home ranges ([102]). A desktop GIS (ArcView© 3.1) with the
Animal Movement Extension was used to examine individual ranging patterns. Using the Animal Movement Extension for
ArcView©, a polygon joining the outermost sighting positions was formed,
indicating the area used by an individual dolphin during the long-term study
period. Range dimensions of the
dolphin were then calculated by GIS with land masses excluded.
Behavioural Data Analysis
When dolphins were sighted during
vessel surveys, their behaviours were recorded through direct observations and
by digital video system. Different
activities were categorized (i.e., feeding, milling/resting, traveling,
socializing) and recorded on the sighting datasheets, and the dolphin
behaviours were taped by a digital video recorder. These data were input into a separate
database with sighting information, which was then used to determine the
distribution of behaviours with desktop GIS.
Survey Results
Land-based Visual Survey
Seasonal Records
During
February 2004 to January 2005, there were a total of 65 marine mammal surveys
undertaken (a total of 360 hours).
Over this period, two residential marine mammals Indo-Pacific Humpback
Dolphin Sousa chinensis and Finless Porpoise Neophocaena phocaenoides were
observed and recorded at
Humpback
dolphins were recorded in all four seasons and most sightings were recorded in
waters around Lan Nai Wan, the sea channel between North and
Number
of sightings and number of individuals of marine mammals are presented in Figures 9.22 & 9.23. The data
presented in these figures have not been corrected for effort and are raw
sightings data.
Figure 9.22 Number
of Sightings and Individuals of Indo-Pacific Humpback Dolphin Sousa
chinensis at
No sighting No sighting
Figure 9.23 Number
of Sightings and Individuals of Finless Porpoise Neophocaena phocaenoides at
Note:
(1) These
data provide supplementary information to check on habitat use in the immediate
vicinity of the proposed works but were not relied upon for characterisation of
dolphin abundance or seasonal distribution in these waters. Instead,
vessel-based survey results (both LNG surveys and long-term data) (presented
below) for the same waters and across
From
the land based surveys, both marine mammal species exhibited a seasonal pattern
at
It
is important to note, owing to the small sample size of the land-based survey
dataset, quantitative comparisons of seasonal abundance with extensive data
collected from vessel-based survey are of limited value. Nevertheless, the usefulness of the
land-based surveys is demonstrated by the fact that dolphins were observed in
the immediate vicinity of South Soko in spring whereas there have been no
sightings of dolphins close to the
Marine Mammal Age Class
The
majority of humpback dolphins recorded during the land-based surveys were
identified as Adults (50 individuals). Juveniles (2 individuals) were also
recorded, as presented in Table 17 of
Annex 9-A and Figure
9.20. Neophocaena phocaenoides were all
adults, except for one juvenile recorded (Table
17 of Annex 9-A).
Vessel Based Visual Survey
Data Collected
In
the 11 month study period (July 2005 to May 2006), 70 days of surveys have been
conducted. During this time, a
total of 5,045 km of transect lines have been surveyed. Among the 5,045 km surveyed transect
lines, 4,097 km (81%) of the total were conducted during relatively calm sea
conditions of Beaufort 0-3, and therefore were useable in the estimation of
density and abundance. Of the
effort conducted in Beaufort 0-3 conditions, 2,409 km was in Southwest Lantau,
396 km was in West Lantau, 385 km was in Northwest Lantau, and 906 km was in
There
were a total of 275 sightings of Indo-Pacific Humpback Dolphins Sousa chinensis. Most sightings took place in West Lantau
(n = 109) and Southwest Lantau (n = 79), with fewer sightings from Northwest
Lantau (n = 62), and the fewest in
Finless
porpoise sightings numbered 29 in total, and all of these occurred in
Distribution
It
is important to recognize that, due to differential survey effort in various
survey subareas, it is not possible to compare densities of dolphins or
porpoises by examining maps of distribution. The distribution maps are only useful
for determining where animals do and do not occur, and for comparing use of the
area on a small scale (within a survey subarea). Comparisons of density or habitat use on
a larger scale should make use of numerical density estimates or the results of
the grid analyses (discuss below).
Dolphins
were observed throughout all of the surveyed areas, and sightings occurred in
most areas, except directly south of the Sha Chau/
The
distribution of young dolphins (Unspotted Calves and Unspotted Juveniles) (Figures 9.28
- 9.31) indicated that they were concentrated in four
areas: (1) southern Deep Bay, (2) around Lung Kwu Chau, (3) all along the West
Lantau coastline, and (4) in Southwest Lantau between Fan Lau and the Soko
Island. The composition of young
animals in
The
distribution of dolphins engaged in feeding and socializing behaviours are
shown in Figures 9.32 - 9.35,
respectively. These will be discussed
in more detail under the Behaviour section below.
As expected, finless porpoises were only observed in the
Abundance and Density
Survey
effort corrected estimates of density and abundance, and their associated
parameters are presented for Table 9.19. For humpback dolphins,
Table 9.19 Estimates of Abundance and Associated Parameters for Humpback
Dolphins and Finless Porpoises in the Three Survey Subareas (NWL is also
discussed in the text), and other Subareas for Comparison
Survey Area |
Survey Days |
L (km) |
n |
f(0) (km-1) |
E (s) |
D (km-2) |
N |
CV (%) |
Indo-Pacific Humpback Dolphin Sousa chinensis |
||||||||
|
|
|
|
|
|
|
|
|
Winter |
19 |
314 |
11 |
4.7071 |
2.72 |
0.23 |
7 |
46 |
Spring |
21 |
354 |
5 |
4.7071 |
4.80 |
0.16 |
5 |
55 |
Summer |
21 |
376 |
5 |
4.7071 |
2.60 |
0.08 |
2 |
49 |
Autumn |
20 |
374 |
9 |
4.7071 |
4.11 |
0.23 |
7 |
42 |
|
|
|
|
|
|
|
|
|
Winter |
36 |
1,051 |
107 |
3.6502 |
3.90 |
0.73 |
63 |
17 |
Spring |
36 |
1,059 |
93 |
3.6502 |
3.51 |
0.57 |
49 |
17 |
Summer |
38 |
1,084 |
113 |
3.6502 |
3.78 |
0.72 |
63 |
15 |
Autumn |
38 |
1,229 |
152 |
3.6502 |
4.16 |
0.94 |
82 |
12 |
|
|
|
|
|
|
|
|
|
Winter |
29 |
448 |
107 |
4.7071 |
4.94 |
2.78 |
77 |
18 |
Spring |
28 |
401 |
92 |
4.7071 |
3.17 |
1.71 |
47 |
20 |
Summer |
29 |
473 |
128 |
4.7071 |
3.84 |
2.45 |
68 |
18 |
Autumn |
34 |
550 |
137 |
4.7071 |
4.80 |
2.81 |
78 |
18 |
|
|
|
|
|
|
|
|
|
Winter |
44 |
1136 |
48 |
4.7071 |
3.10 |
0.31 |
20 |
20 |
Spring |
37 |
1051 |
8 |
4.7071 |
5.38 |
0.10 |
6 |
44 |
Summer |
38 |
1374 |
47 |
4.7071 |
3.47 |
0.28 |
18 |
27 |
Autumn |
31 |
908 |
37 |
4.7071 |
4.57 |
0.44 |
29 |
27 |
Finless porpoise Neophocaena
phocaenoides |
||||||||
|
|
|
|
|
|
|
|
|
Winter |
44 |
1136 |
22 |
5.2054 |
1.9 |
0.09 |
8 |
35 |
Spring |
37 |
1051 |
26 |
5.2054 |
2.6 |
0.17 |
15 |
39 |
Summer |
38 |
1374 |
1 |
5.2054 |
1.0 |
< 0.01 |
0 |
78 |
Autumn |
31 |
908 |
2 |
5.2054 |
1.5 |
0.01 |
1 |
67 |
Lamma(4) |
|
|
|
|
|
|
|
|
Winter |
- |
1173 |
17 |
6.10 |
2.4 |
0.10 |
17 |
32 |
Spring |
- |
1126 |
35 |
3.75 |
5.9 |
0.52 |
90 |
32 |
Summer |
- |
1007 |
4 |
3.75 |
2.0 |
0.02 |
4 |
50 |
Autumn |
- |
1283 |
12 |
3.84 |
1.6 |
0.04 |
7 |
32 |
|
|
|
|
|
|
|
|
|
Winter |
- |
400 |
6 |
7.68 |
1.3 |
0.07 |
14 |
63 |
Spring |
- |
962 |
3 |
79.47 |
1.7 |
0.02 |
4 |
60 |
Summer |
- |
940 |
18 |
5.50 |
2.8 |
0.17 |
32 |
36 |
Autumn |
- |
667 |
16 |
4.65 |
2.0 |
0.14 |
26 |
36 |
Note: (1) L=total length of transect surveyed;
n=number of on-effort sightings; f(0)=trackline
probability density; E(s)=unbiased mean group size; D= density of individuals;
N=individual abundance; and CV=coefficient of variation.
(2) Only data collected in Beau 0-3
conditions are included here.
(3) As explained previously, the individual
density value (D) represents an estimate of the number of individual dolphins /
porpoises in a 1 km2 grid square area.
(4) Data extracted from
Jefferson et al. 2002 ([105]) for comparative purposes.
Note (3) is not applicable to this data.
Finless
porpoises were only seen in Table 9.19).
However, based on the latest data, this situation may have changed as
sightings were higher in the waters of the Po Toi Islands. In monitoring conducted in 2003 to 2005,
finless porpoise sightings in South Lantau (12 sightings) were higher than in
Lamma (2), Nine Pins (4) and Sai Kung (4), but lower than in Po Toi (15) ([106]) .
For
the Table 9.20. Encounter rates increased from summer to
autumn and then increased again from autumn to winter, finally decreasing
dramatically in spring months.
Table 9.20 Individual
Encounter Rate Information for Dolphins in
Season |
No. Surveys |
Individuals |
Encounter Rate |
Std. Dev. |
Summer |
7 |
36 |
24.9 |
31.65 |
Autumn |
6 |
53 |
46.5 |
20.62 |
Winter |
3 |
65 |
166.3 |
52.58 |
Spring |
6 |
18 |
17.1 |
20.93 |
Note: (1) This analysis uses only data collected by
surveys for this EIA Study due to the unique designation of this survey
subarea.
Long-term Trends in Abundance and Density
In
order to investigate long-term trends in abundance of dolphins and porpoises in
the survey subareas, data from the 1996-2006 line-transect dataset were used to
calculate a time series of density and abundance estimates (Table 9.21). It should be noted that
there were limitations on the temporal resolution attainable since it is
necessary to maintain an adequate level of precision for the estimates (as
indicated by lower CV values). As
such, it was only possible to provide annual estimates for the
Table 9.21 Trends
in Estimates of Abundance and Associated Parameters
for Humpback Dolphins and Finless Porpoises in the Three Survey Subareas
Survey Area |
Survey Days |
L (km) |
n |
f(0) (km-1) |
E (s) |
D (km-2) |
N |
CV (%) |
Indo-Pacific Humpback Dolphin Sousa chinensis |
||||||||
|
|
|
|
|
|
|
|
|
1997/98/99 |
22 |
514 |
10 |
4.7071 |
3.60 |
0.17 |
5 |
24 |
2005 |
35 |
543 |
7 |
4.7071 |
3.71 |
0.11 |
3 |
52 |
2006 |
24 |
360 |
13 |
4.7071 |
3.23 |
0.27 |
8 |
43 |
|
|
|
|
|
|
|
|
|
1997 |
6 |
67 |
9 |
4.7071 |
6.33 |
2.00 |
55 |
57 |
2002 |
10 |
108 |
39 |
4.7071 |
3.65 |
3.10 |
86 |
23 |
2003 |
43 |
661 |
175 |
4.7071 |
4.80 |
2.99 |
83 |
16 |
2004 |
39 |
641 |
160 |
4.7071 |
4.02 |
2.36 |
65 |
15 |
2005 |
57 |
1015 |
205 |
4.7071 |
3.88 |
1.84 |
51 |
10 |
2006 |
17 |
273 |
70 |
4.7071 |
4.64 |
2.80 |
77 |
19 |
|
|
|
|
|
|
|
|
|
1997/98 |
23 |
444 |
16 |
4.7071 |
5.14 |
0.44 |
29 |
42 |
1999/00 |
20 |
430 |
13 |
4.7071 |
2.15 |
0.15 |
10 |
38 |
2001/02 |
23 |
448 |
22 |
4.7071 |
3.14 |
0.36 |
24 |
31 |
2003/04 |
20 |
536 |
23 |
4.7071 |
3.74 |
0.38 |
25 |
30 |
2005/06 |
64 |
2611 |
66 |
4.7071 |
3.85 |
0.23 |
15 |
21 |
Finless porpoise Neophocaena
phocaenoides |
||||||||
|
|
|
|
|
|
|
|
|
1997/98 |
11 |
230 |
8 |
5.2054 |
2.38 |
0.22 |
14 |
55 |
1999/00 |
10 |
196 |
4 |
5.2054 |
2.50 |
0.13 |
9 |
111 |
2001/02 |
13 |
235 |
8 |
5.2054 |
3.00 |
0.27 |
17 |
61 |
2003/04 |
12 |
328 |
4 |
5.2054 |
2.25 |
0.07 |
5 |
65 |
2005/06 |
35 |
1197 |
25 |
5.2054 |
2.08 |
0.11 |
7 |
30 |
Note: (1) L=total length of transect surveyed;
n=number of on-effort sightings; f(0)=trackline
probability density; E(s)=unbiased mean group size; D= density of individuals;
N=individual abundance; and CV=coefficient of variation.
(2) Only data collected in Beau 0-3
conditions are included here.
(3) For 2006, estimates are incomplete, with
only winter and spring data included.
(4) As explained previously, the density of
individuals value (D) represents an estimate of the number of individual
dolphins / porpoises in a 1 km2 grid square area.
Based
on examination of estimates of dolphin density over time, it appears there are no
consistent trends for any of the surveyed subareas. It should be borne in mind, a degree of caution is warranted in interpreting these
figures to take account of the level of precision achievable. In general, in
Grid Analysis of Habitat Use (July 2005 – May 2006)
Grid
analysis of habitat use provides the best way to compare dolphin and porpoise
use of specific areas, especially on a small scale. Because the data are standardized for
differential survey effort, it is possible to compare density of two grids,
even if they are in different survey subareas.
Using
the line-transect survey data from the 11 month study, combined with AFCD data
collected from the same period, survey effort data and dolphin/porpoise
sighting data were retrieved to calculate DPSE values for 158 grids among the
four study areas. The maps with
density (DPSE) of humpback dolphins and finless porpoises with corrected survey
effort per km2 of the four areas are shown in Figures 9.38 and 9.39
respectively.
The
average DPSE values of the 158 grids for humpback dolphins in the four survey
areas was 0.28 Among them, West
Lantau represented the highest use area for dolphins, with an average DPSE
value of 0.67. Moreover, Table 9.22).
Table
9.22 Average
DPSE for Different Survey Subareas during the Study
|
#
grids |
Ave.
DPSE |
#
grids w/ DPSE>1 |
|
26 |
0.06 ±
0.12 |
0 |
|
28 |
0.44 ±
0.54 |
2 |
|
34 |
0.67 ±
0.51 |
10 |
|
70 |
0.09 ±
0.13 |
0 |
Total |
158 |
0.27 ±
0.42 |
2 (ave) |
Habitat
use of humpback dolphins was very uneven among the 1 km2 grids within the 4
areas. In
In
Grid Analysis
of Habitat Use (Seasonal)
To
examine the seasonal habitat use patterns of humpback dolphins and finless
porpoises quantitatively in recent years, survey effort and dolphin/porpoise
sighting data from the long-term monitoring database and the additional LNG
survey data were stratified by season to calculate DPSE values (total number of
dolphin/porpoises per unit of survey effort) within 1 km2 grids in the survey
subareas. For humpback dolphins,
line-transect data collected during 2003-06 were used, and DPSE values for grid
squares in Deep Bay, Northwest Lantau, Northeast Lantau, West Lantau, Southwest
Lantau and Southeast Lantau were examined (see Figure 9.40). For finless porpoise, line-transect data
collected during 2002-06 were used (to allow larger sample size). Only Southwest and
Dolphins: Humpback dolphins showed different levels
of seasonal differences in habitat use among the six survey areas (Figure 9.40). Seasonal habitat use patterns were less
obvious in West Lantau and
On
the other hand, Northeast Lantau and
In
In
Porpoises: Seasonal habitat use patterns for
finless porpoises were also examined in Southwest and
In
winter months, porpoises preferred to use the waters around the
Seasonal Habitat Partitioning: The waters
around the
Individual Movements and Patterns of Use
During
the study period, a number of individual dolphins in all four of the study
subareas were successfully identified (Figures 9.42 & 9.43). The individuals identified so far are
listed in Table 9.23, along with an
assessment of the importance of the subarea as part of the dolphin’s home
range. The subarea was considered
an important part of the dolphin’s range if >25% of the sightings of that
individual occurred in the area.
Table 9.23 Individual
Humpback Dolphins Observed during the LNG Study (July 2005 – May 2006)
Dolphin’s ID |
Total sightings (1) |
EIA Study sightings (2) |
SWL (3) (4) |
DB (3) (4) |
|
WL (3) (4) |
HR Study? |
CH03 |
18 |
1 |
1
(6%) |
|
4
(22%) |
|
Yes |
CH06 |
25 |
2 |
3
(12%) |
|
|
14 (56%) |
Yes |
CH37 |
7 |
1 |
1
(14%) |
|
1
(14%) |
|
|
DB02 |
2 |
2 |
|
2 (100%) |
|
|
|
DB03 |
1 |
1 |
|
1 (100%) |
|
|
|
EL01 |
43 |
1 |
|
|
6
(14%) |
2
(5%) |
Yes |
EL03 |
5 |
1 |
1
(20%) |
|
1
(20%) |
1
(20%) |
|
EL07 |
57 |
1 |
|
|
2
(4%) |
2
(4%) |
Yes |
NL11 |
45 |
3 |
|
1
(2%) |
16 (36%) |
|
Yes |
NL24 |
95 |
2 |
|
|
18
(19%) |
7
(7%) |
Yes |
NL37 |
35 |
1 |
|
|
5
(14%) |
2
(6%) |
Yes |
NL46 |
15 |
1 |
|
|
8 (53%) |
2
(13%) |
Yes |
NL59 |
18 |
1 |
|
|
3
(17%) |
3
(17%) |
Yes |
NL60 |
16 |
1 |
|
|
8 (50%) |
2
(13%) |
Yes |
NL76 |
10 |
1 |
|
|
6 (60%) |
|
Yes |
NL98 |
47 |
1 |
|
|
6
(13%) |
7
(15%) |
Yes |
NL123 |
43 |
5 |
|
|
11 (26%) |
2
(5%) |
Yes |
NL128 |
10 |
1 |
2
(20%) |
|
1
(10%) |
6 (60%) |
Yes |
NL136 |
8 |
1 |
|
|
5 (63%) |
|
|
NL139 |
42 |
1 |
|
|
5
(12%) |
5
(12%) |
Yes |
NL141 |
31 |
1 |
|
|
6
(19%) |
3
(10%) |
Yes |
NL150 |
7 |
1 |
|
1
(14%) |
6 (86%) |
|
|
NL169 |
10 |
3 |
|
3
(30%) |
6 (60%) |
|
Yes |
NL170 |
4 |
1 |
|
|
2 (50%) |
2 (50%) |
|
NL181 |
14 |
5 |
|
4
(29%) |
9 (64%) |
|
Yes |
NL191 |
9 |
1 |
|
|
2
(22%) |
2
(22%) |
|
NL202 |
6 |
1 |
|
|
4 (67%) |
2 (33%) |
|
SL07 |
13 |
2 |
2
(15%) |
|
|
7 (54%) |
Yes |
SL35 |
5 |
3 |
3 (60%) |
|
|
2 (40%) |
|
SL36 |
1 |
1 |
1 (100%) |
|
|
|
|
SL37 |
1 |
1 |
1 (100%) |
|
|
|
|
WL11 |
16 |
2 |
|
|
6
(38%) |
3
(19%) |
Yes |
WL25 |
22 |
2 |
1
(5%) |
|
1
(5%) |
15 (68%) |
Yes |
WL26 |
4 |
1 |
1
(25%) |
|
|
3 (75%) |
|
WL30 |
2 |
1 |
|
1 (50%) |
|
1 (50%) |
|
WL48 |
2 |
1 |
|
|
|
2 (100%) |
|
WL51 |
4 |
2 |
2 (50%) |
|
|
2 (50%) |
|
Note: (1) Total sightings in the long-term
database.
(2) Sightings in ERM’s surveys (July 2005 –
May 2006) for this EIA Study.
(3) Number of sightings in each of the LNG
survey areas (along with the proportion of the total in parentheses).
(4) Areas with >25% of the total sightings
are in bold.
Twelve
individuals of humpback dolphin were identified in the
In
the
The
ranging patterns of 21 individual dolphins identified during the 11 month
surveys are shown in Figures
9.42 & 9.43. Among these individuals, 18 were
identified in Northwest Lantau, 16 in West Lantau, 4 in Southwest Lantau, and 3
in
Currently,
among the 398 individuals identified in
Group Size and Composition
Humpback
dolphin average group size was similar for the Northwest Lantau, West Lantau,
and Southwest Lantau subareas (3.6-4.2 dolphins/group); however it was smaller for
the Deep Bay subarea (3.0 dolphins) (Table
9.24).
Table 9.24 Average
Group Size for Dolphins and Porpoises among the Different Survey Subareas
Species |
Subarea |
N |
Mean |
±SD |
Range |
Humpback dolphin |
|
55 |
3.0 |
2.4 |
1 to 12 |
|
|
62 |
3.7 |
2.9 |
1 to 17 |
|
|
843 |
4.2 |
3.8 |
1 to 26 |
|
|
89 |
3.6 |
3.0 |
1 to 17 |
Finless porpoise |
|
0 |
- |
- |
- |
|
|
0 |
- |
- |
- |
|
|
0 |
- |
- |
- |
|
|
186 |
2.9 |
2.4 |
1 to 12 |
Finless
porpoise average group size (all sightings from
Due
to the need to observe dolphin groups for extended periods at close range
(which somewhat conflicted with the goal of completing all the transect lines),
the surveys were only able to accurately record complete age class composition
for a portion of the groups observed in each area (Table 9.25Table 9.25). In
this subsample, all age groups were represented in each of the four survey
subareas, except that no Unspotted Calves were found in
Table 9.25 Age
Class Composition of Groups of Dolphins among the Four Survey Subareas
(Percentage of Total Given in Parentheses). Data included this study and long-term
data. Note that only groups in
which the composition of the entire group was determined are presented
Area |
No. of
Groups |
UC |
UJ |
SJ |
SS |
SA |
UA |
|
19 |
8 (7%) |
8 (14%) |
13
(24%) |
14
(25%) |
13
(23%) |
4 (7%) |
|
16 |
5 (11%) |
5 (11%) |
6 (13%) |
12
(26%) |
18
(39%) |
5 (11%) |
|
24 |
4 (6%) |
4 (6%) |
21
(30%) |
15
(21%) |
19
(27%) |
10
(13%) |
|
231 |
78 (8%) |
78 (8%) |
206
(22%) |
196
(21%) |
210
(23%) |
211
(24%) |
Behaviour
Dolphin
sightings associated with different types of activities were examined on GIS to
determine important areas for certain types of dolphin activity. For sightings with dolphins engaged in
feeding activities, most were made along the coastal waters of
In
Northwest Lantau, most of the feeding activities occurred around Lung Kwu Chau
and Sha Chau; while in
Dolphins
were occasionally observed socializing during the study period, and there was
no particular area where sightings associated with socializing activities were
frequently observed.
9.4
Evaluation of Ecological
Importance of the Study Area
The
existing conditions of the marine ecological habitats and resources in the
waters of the proposed LNG terminal at
·
Naturalness
·
Size
·
Diversity
·
Rarity
·
Re-creatability
·
Fragmentation
·
Ecological
Linkage
·
Potential
Value
·
Nursery
Ground
·
Age
·
Abundance
As
noted previously, the marine waters and coastal habitats of the
9.4.1
Intertidal Habitats
The
criteria listed below have been applied to the information gathered or reviewed
on the marine ecology of the intertidal habitats at Table 9.26).
Table 9.26 Ecological
Importance of Intertidal Habitats at
Criteria |
Rocky Shore |
Artificial
Shorelines |
|
Naturalness |
The natural rocky shoreline is
interspersed with areas of artificial seawall and are largely undisturbed by
human activity |
Artificial constructed habitat. |
The shores are
moderately disturbed |
Size |
Large in extent with the majority of |
The length of the artificial shorelines at |
Small. The two sandy shores in the study area at |
Diversity |
Typical of exposed and semi-exposed rocky shores in |
Low. Artificial shores support similar assemblages to
natural intertidal shores. |
Very low. Only one species was recorded on the sandy shore
and in low numbers |
Rarity |
No species recorded are considered rare or of recognised
conservation interest. |
No species recorded were rare or of recognised
conservation interest |
No species recorded are considered rare or of recognised
conservation interest. |
Re-creatability |
The habitat is re-creatable. |
N/A |
The habitat is re-creatable. |
Fragmentation |
Low. Rocky shore is predominant intertidal habitat. |
N/A |
Moderate. |
Ecological Linkage |
The habitat is not functionally linked to any high value habitat in a
significant way. |
The habitat is not functionally
linked to any high value habitat in a significant way |
The habitat is not functionally
linked to any high value habitat in a significant way |
Potential Value |
Low. |
None identified |
Low to moderate. |
Nursery Area |
No significant records identified during the literature
review or field surveys. |
No significant records identified during the literature
review or surveys |
Higher
abundance of nearshore fish fry were reported at Pak Tso Wan. No significant records identified in the sandy shores
during the literature review or surveys. |
Age |
n/a for these assemblages as the life cycle of the fauna and flora is
short. |
The artificial seawall has been in place since the
detention centre was built in 1989 |
n/a for these assemblages as the life cycle of the fauna is short. |
Abundance |
Moderate.
Typical species of similar composition and abundance as other exposed and
semi-exposed rocky shores in |
Low. Assemblages similar to nearby rocky shores but in
lower abundance. |
Very low. This
finding is typical of semi-exposed sandy beaches in |
SUMMARY |
Rocky shore
supports assemblages typical of exposed and semi-exposed shores in Ecological
Importance - Medium. |
Artificial
shores support established assemblages similar to natural rocky shore but
with lower abundance.
Ecological
Importance - Low. |
Ecological Importance – Medium for Pak Tso Wan Low for the
remaining |
Note: n/a: Not Applicable
The
application of these criteria has led the artificial shoreline and natural
rocky shore at Black Point to be classified as low ecological importance (Table 9.26).
Table 9.27 Ecological
Importance of Intertidal Habitats at Black Point
Criteria |
Rocky Shore |
Artificial
Shorelines |
Naturalness |
The natural rocky shoreline
is interspersed with areas of artificial seawall and are largely
undisturbed prior to the development of the thermal power station (BPPS)
commenced in 1993. |
Artificial, constructed habitat. |
Size |
Large. Within the Study Area, rocky shore habitat are approximately 390 m in total length and are
predominant habitat on Black Point headland. |
Large. The total length of the
artificial shore in the Study Area at Black Point is approximately 522 m and
are predominant habitat to the north of the power station. |
Diversity |
Low. The intertidal communities are composed of typical biota
of semi-exposed rocky shores in |
Records indicate that sloping artificial shores support
similar assemblages to natural intertidal shores. |
Rarity |
No species recorded are considered rare or of recognised
conservation interest. |
No species recorded are considered rare or of recognised
conservation interest.. |
Re-creatability |
The habitat can be re-created. |
n/a. |
Fragmentation |
Low. The surrounding environment contains similar
intertidal habitats. |
Low. The surrounding coastlines are composed of a mixture
of natural and artificial intertidal shores. |
Ecological Linkage |
The habitat is not functionally linked to any high value
habitat in a significant way. |
The habitat is not functionally linked to any high value
habitat in a significant way. |
Potential Value |
Unlikely that the site can develop conservation interest. |
Unlikely to become an area of conservation value |
Nursery Area |
No significant records identified during the literature review
or field surveys. |
No significant records identified during the literature
review or surveys |
Age |
n/a for these assemblages as the life cycle of the fauna and flora is
very short. |
The artificial seawall has been in place since the site access
of Black Point Power Station was obtained in March 1993. |
Abundance |
Typical of other semi exposed shores in |
Lower abundance than natural rocky shore habitat. |
SUMMARY |
The fauna of the
intertidal region appears to be typical of semi exposed shores in Ecological
Importance - Low. |
The fauna of
the intertidal region of the artificial shores is reported to support a
similar diversity and abundance of intertidal organisms as natural
shores. Ecological
Importance - Low. |
Note: n/a: Not
Applicable
The
application of these criteria has led the artificial shoreline, natural rocky shore
and sandy shore at Shek Pik to be classified as low ecological importance (Table 9.28Table 9.28).
Table 9.28 Ecological
Importance of Intertidal Habitats at Shek Pik
Criteria |
Rocky Shore |
Artificial
Shorelines |
|
Naturalness |
Natural rocky shoreline occurs along the
mouth of the bay away from developed areas and is largely undisturbed by
human activity |
Artificial constructed habitat. |
Owing to their
location close to Shek Pik maximum security prison the shores are largely
undisturbed. |
Size |
Large in extent with the majority of the shoreline at the
periphery of the study area consisting of this habitat |
Medium in extent. The artificial shorelines
at Shek Pik occurs in the middle part of the bay. |
Large. The two sandy shores in the study area at |
Diversity |
The shore was characterised as a relatively low diversity
of intertidal species shores compared to other semi-exposed rocky shores in |
Low. Artificial shores support similar assemblages to
natural intertidal shores. |
Very low. Only one species was recorded on the sandy shore
and in low numbers |
Rarity |
No species recorded are considered rare or of recognised
conservation interest. |
No species recorded were rare or of recognised
conservation interest |
No species recorded are considered rare or of recognised
conservation interest. |
Re-creatability |
The habitat is re-creatable. |
N/A |
The habitat is re-creatable. |
Fragmentation |
Low. Rocky shore is common intertidal habitat. |
N/A |
Low. |
Ecological Linkage |
The habitat is not functionally
linked to any high value habitat in a significant way. |
The habitat is not functionally
linked to any high value habitat in a significant way |
The habitat is not functionally
linked to any high value habitat in a significant way |
Potential Value |
Low. |
None identified |
Low. |
Nursery Area |
No significant records identified during the literature
review or field surveys. |
No significant records identified during the literature
review or surveys. |
No significant records identified during the literature
review or surveys. |
Age |
n/a for these assemblages as the life cycle of the fauna and flora is
short. |
The artificial seawall was probably built as part of the
prison development in the 1980s. |
n/a for these assemblages as the life cycle of the fauna is short. |
Abundance |
Relatively low.
Typical species of similar composition but generally lower abundance compared
to other semi-exposed rocky shores in |
Low. Assemblages similar to nearby rocky shores. |
Very low. This
finding is typical of semi-exposed sandy beaches in |
SUMMARY |
Rocky shore
supports assemblages typical of semi-exposed shores in Ecological
Importance -Low. |
Artificial
shores support established assemblages similar to natural rocky shore but
with lower abundance.
Ecological
Importance - Low. |
Ecological
Importance – Low. |
Note: n/a: Not
Applicable
9.4.2
Subtidal Habitats
The
criteria listed above have been applied to the information gathered or reviewed
on the marine ecology of the subtidal hard surface benthic habitat within the
Study Area. The habitat has been classified
as of low ecological value (Table 9.29Table 9.29).
Table 9.29 Ecological
Importance of the Subtidal Hard Substrate Habitat at
Criteria |
Subtidal Hard
Surface Habitat along Natural Shoreline |
Subtidal Hard
Surface Habitat along Artificial Shoreline |
Naturalness |
Habitat is largely natural. There is
evidence at the site of indirect impacts to the assemblages through poor
water quality and deposited sediments. |
The artificial habitat will have been
largely undisturbed since the decommissioning of the detention centre. There is evidence at the site of
indirect impacts to the assemblages through poor water quality and deposited
sediments. |
Size |
Medium in extent. Predominant habitat fringing |
The assemblages at |
Diversity |
A total of fifteen species of hard corals, including Porites lobata, Psammocora superficialis, Coscinarea sp., Pseudosiderastrea tayami, Turbinaria peltata, Balonophyllia sp.,Plesiastrea versipora, Leptastrea
pruinosa, Cyphastrea sp,
Echinophyllia sp, Favites abdita,
Goniopora stutchburyi, Goniopora lobata, Oulastrea crispata and Tubastrea
sp./ Dendronophyllia sp., and 4
genera of octocorals, including Dendronepthya,
Euplexaura, Echinomuricea and Echinogorgia were recorded, with low
diversity on west and east coast and moderate diversity on south coast of
South Soko in comparison to other sites in Hong Kong. |
One hard coral Oulastrea
crispata and one octocoral Euplexaura
were recorded, this is very low in comparison to
other sites in |
Rarity |
With the exception of the little known Pseudosiderastrea tayami recorded at
two locations (Transects J & K) on the south coast of South Soko, all
species of hard and soft corals are commonly recorded on rocky coasts across |
All species of hard and soft corals are commonly recorded
on rocky coasts in |
Re-creatability |
Hard bottom substrata may be recolonised by subtidal
organisms including corals. |
Hard bottom substrata may be recolonised by subtidal
organisms including corals. |
Fragmentation |
Low. Similar subtidal habitats are situated around the
shores of |
Low. Similar subtidal hard surface habitats are situated
around the shores of South Soko, |
Ecological Linkage |
The habitat is not functionally
linked to any high value habitat in a significant way. |
The habitat is not functionally
linked to any high value habitat in a significant way. |
Potential Value |
Low. Conditions are marginal for coral growth this habitat
supports sparse coral cover. High
turbidity and high rates of sedimentation mean that the area is unlikely to
become an area of coral conservation, although the location, where the little
known, hardy coral Pseudosiderastra
tayami is common, represents a notable record. |
Very low. This
habitat supported
few coral species
which were sparse in abundance. Conditions are not highly suited for
coral growth. High turbidity and
high rates of sedimentation mean that the area is unlikely to become an area
of coral conservation. |
Nursery Area |
No significant records identified during the literature
review or field surveys. |
No significant records identified during the literature
review or field surveys. |
Age |
Coral colonies were scattered and small. No large mature
hard coral colonies were observed. |
Coral colonies were scattered and small. No large mature
coral colonies were observed. |
Abundance |
Very low live coral coverage was found in the study area. |
Very low live coral coverage was found in the study area. |
SUMMARY |
Coral cover is
very low in comparison to other sites in Ecological Importance – Low except sites at
Transect J & K on south coast of South Soko –Medium |
Coral cover is
very low in comparison to other sites in Ecological
Importance - Low. |
Note: n/a: Not Applicable
The
criteria listed above have been applied to the information gathered or reviewed
on the marine ecology of the subtidal soft bottom benthic habitat at Table 9.30).
Table 9.30 Ecological
Importance of the Subtidal Soft Benthos Assemblages at
Criteria |
Subtidal Soft
Benthos at |
Subtidal Soft
Benthos along the
Corridor of the Proposed Submarine Natural Gas Pipeline (AC, PH, TO, MP1,
MP2, UR & BP1) |
Naturalness |
Habitat disturbed to some extent by fisheries vessel
trawling activities and is influenced by discharges from the |
Habitat disturbed to some extent by fisheries vessel
trawling activities and is influenced by discharges from the |
Size |
Habitat is large in extent. |
Habitat is large in extent. Pipeline alignment is approx
40 Km |
Diversity |
The assemblages are of relative higher
diversity (number of benthic species recorded per unit area above the mean
value of the CityU (2002) data) compared to other areas in the |
The assemblages are of similar diversity
to other areas in the |
Rarity |
No infaunal organisms were found that are considered as
rare. One epifaunal species listed as a Class II protected species in |
No organisms were found that are considered as rare or of
recognised conservation interest. |
Re-creatability |
Benthic organisms may recolonise disturbed seabed areas. |
Benthic organisms may recolonise disturbed seabed areas. |
Fragmentation |
The habitat is not fragmented. |
The habitat is not fragmented. |
Ecological Linkage |
The habitat is not functionally
linked to any high value habitat in a significant way. |
The habitat is not functionally
linked to any high value habitat in a significant way. |
Potential Value |
It is unlikely that the habitat could develop conservation
interest. |
It is unlikely that the habitat could develop conservation
interest. |
Nursery Area |
No significant records identified in the review or
surveys. |
No significant records identified in the review or
surveys. |
Age |
The fauna appear to be typical of those present in |
The fauna appear to be typical of those present in |
Abundance |
In comparison to other parts of the southern and western
waters the assemblages are of moderate abundance. |
In comparison to other parts of the western waters the
assemblages are of moderate abundance. |
SUMMARY |
The sediments
support average diversity and abundance of benthic organisms that are typical
of Ecological Importance – Medium except SK3 in Tung Wan – High. |
The sediments
support average diversity and abundance of benthic organisms that are typical
of Ecological
Importance – Low. |
Note: n/a: Not Applicable
9.4.3
Marine Mammal Habitat off South Soko and
along the Proposed Submarine Pipeline Route
The
same assessment criteria have been applied to the marine waters within the
Study Area with regard to the usage of the area by marine mammals. Both species are sighted in the waters
of Table 9.31).
Table 9.31 Ecological
Importance of the Marine Waters off
Criteria |
Marine Waters around |
Along the Corridor of the Proposed Submarine Natural
Gas Pipeline |
Naturalness |
Close
proximity to the artificial shoreline and marine traffic lanes in |
Largely
undisturbed in West Lantau and adjacent to the |
Rarity |
The South
Lantau waters (extending from Fan Lau to south of Cheung Chau) is the only
area in Hong Kong where there is a major spatial overlap in the distribution
of Indo-Pacific Humpback dolphin and Finless Porpoises. There are however marked seasonal
differences of these species use of Around South Soko, Indo-Pacific humpback dolphin Sousa chinensis has been recorded in
coastal waters to the east (Tung Wan) and north (Lan Nai Wan) of South Soko,
and the finless porpoise has been recorded in the west (Sai Wan) and north
(the waters between North and South Soko) of South Soko. |
Indo-Pacific humpback dolphin Sousa chinensis has been recorded along the majority of the
waters of the route, whereas, sightings of the Neophocaena phocaenoides (are uncommon, if at all, along the
entire route) |
Re-creatability |
n/a |
n/a |
Ecological Linkage |
Preferred marine mammal habitat occurs to the north
(north-western Lantau) for humpback dolphins and west ( |
Route lies in waters that are utilised by humpback
dolphins as part of their larger habitat. West Lantau and |
Potential Value |
|
West Lantau and |
Nursery Area |
Not key nursery areas in the review of
baseline conditions or field surveys. |
Review of baseline conditions and field
surveys, indicated higher sightings of young animals off |
Abundance |
Seasonal changes in the distribution patterns of dolphins
were observed near the areas of the proposed LNG terminal and pipeline route
alignment, with comparatively higher sightings in spring and winter
months. Abundance of dolphins is
low at South Soko when compared to the preferred habitat in West and
Northwest Lantau, however, Southwest Lantau is in the fourth most important
dolphin habitat in |
Northwest and |
SUMMARY |
Sightings of
humpback dolphins and finless porpoise (occupying different areas) have been
made in these waters. The number
of sightings is low and seasonally varies. Ecological Importance: -
Marine Waters at Tung Wan and Sai Wan of
South Soko Low for Sousa chinensis, Medium for Neophocaena phocaenoides(2).
-
Marine Waters at the southeast of -
Marine Waters along the Corridor of the Proposed water main and submarine cable circuit Medium for both Sousa chinensis and Neophocaena
phocaenoides. |
Route passes
through waters where sightings are common and consistent throughout the
year. Sightings of finless
porpoise are either low, or not all, along the route. Ecological Importance: Medium for both Sousa
chinensis and Neophocaena
phocaenoides west of Medium in southwest Lantau for Sousa chinensis, Low
for Neophocaena phocaenoides. High in west and northwest Lantau only for Sousa chinensis (1). Low at Black Point landing area only for Sousa chinensis. |
Note: (1) The rank of
‘high’ is the highest rank that can be accorded to a habitat under ERM’s system
for evaluating habitat importance. While both west and northwest Lantau are
deemed to be of high ecological importance, it is recognised that
(2) It is
noted that as a whole, the marine waters around
9.4.4
Species of Recognised or Potential
Conservation Interest Conservation Interest
In
accordance with EIAO-TM Annex 8
criteria, species of recognised or potential conservation value and their
conservation and protection status, are presented in Table 9.32.
Table
9.32 Species
of Recognised or Potential Conservation Interest within the Study Area
Common Name |
Scientific Name |
Protection Status |
Distribution, Rarity and other
Notes |
Chinese
White Dolphin (also known as the Indo-Pacific Humpback dolphin) |
Sousa chinensis |
Wild
Animals Protection Ordinance, Animals and Plant Ordinance, Class I Protected
Species in the PRC, CITES Appendix 1, IUCN-listed (data deficient), Listed in
UN Biodiversity Treaty |
Range
across Pearl River estuary and across Hong Kong western and Southern Waters
from |
Finless
Porpoise (also known as the Black
Finless Porpoise) |
Neophocaena phocaenoides |
Wild
Animals Protection Ordinance, Animal and Plants Ordinance, Class I Protected
Species in the PRC. CITES Appendix 1, IUCN-listed (data deficient) |
Range
from South Lantau to |
Amphioxus |
Branchiostoma belcheri |
Not
protected in |
Recent
studies indicate wider distribution than previously known. Recorded from across Hong Kong eastern
waters from Sai Kung to |
False
Pillow Coral |
Pseudosiderastrea tayami |
Wild
Animals Protection Ordinance, Animal and Plants Ordinance |
Little
known species in Hong Kong recently discovered following study to clarify
identity of |
|
|
|
|
9.5
Summary
The
findings from the literature review and field surveys on marine ecological
conditions are detailed above and are summarized as follows.
The
marine ecological habitats in the immediate vicinity of the
The
key finding of the literature review was the recorded presence in the waters in
southern Lantau of both the Indo-Pacific humpback dolphin Sousa chinensis and the Finless Porpoise Neophocaena phocaenoides.
Both species are sighted in the waters of
The
review highlighted that the waters around the
The ecological importance of the
habitats was determined through reference to the following:
·
Literature
review;
·
Findings
of the field surveys;
·
Comparison
with other outlying islands in Hong Kong as well as
·
Annexes 8 and 16 of the
EIAO TM.
9.5.1
Dolphins and Porpoises
For
this study, an extensive programme of vessel-based surveys
have been conducted to supplement data available from ongoing long-term
AFCD monitoring. These surveys have
provided a detailed overview of dolphin utilisation of Hong Kong western waters
spanning South West Lantau, West Lantau, North West Lantau and
In
contrast,
Southwest
Lantau had lower levels of dolphin density (0.10 -
0.44 dolphins km-2) and abundance
(26 - 29 dolphins) than West Lantau but higher than
Northwest
Lantau had lower levels of dolphin density (0.57-0.94) but
similar abundance (49-82) compared to
Finless
Porpoises were only seen in
9.5.2
Subtidal Hard Bottom Habitats
Dive
surveys at
Subtidal Soft
Bottom Habitats
A
total of 96 grab samples were taken from 16 sites during both the wet and dry
seasons: 8 of the sites (48 grabs) were located close to
Intertidal
Hard Bottom Habitats
Quantitative transect surveys and
spotchecks were conducted on natural rocky shore and artificial seawalls on the
west, east and south coasts of
Intertidal
Soft Bottom Habitats
The
sandy shores at
Detailed
and comprehensive seasonal surveys were conducted examining the major habitats
and species surrounding the Table 9.33.
Table 9.33 Marine
Ecology Baseline Surveys
Survey Type |
Methodology |
Date |
Intertidal Assemblages at |
Rocky shore/ artificial shoreline Quantitative (belt transects at 9 locations) survey, three 100 m belt
transects (at high, mid and low intertidal zones) for each location, covered
both wet and dry seasons. Quantitative
(line transects at two locations) survey, 50 x 50 x 50cm core at three points
(high, mid and low
intertidal zones) along each of the transects, covered both wet and dry seasons. |
8 & 9 March, 28 & 29 July and 14
September, 17 & 28 December 2004, 29 & 30 September 2005 and 27
January 2006 |
Intertidal Assemblages at Black Point |
Rocky shore/ artificial shoreline Quantitative (belt transects at 6
locations) survey, three 100 m belt transects (at high, mid and low
intertidal zones) for each location, covered both wet and dry seasons |
22 & 23 March and 15 & 30 July
2004. |
Intertidal Assemblages at Shek Pik |
Rocky shore/ artificial shoreline Quantitative (belt transects at 1 locations) survey, three 100 m belt transects
(at high, mid and low intertidal zones) covered both wet and dry seasons. Quantitative (line transects at 3 locations)
survey, 50 x 50 x 50cm core at three points (high, mid and low intertidal zones) along each of the transects, covered both wet and dry seasons. |
30 August 2005 & 14 March 2006 |
Subtidal Benthic Assemblages |
Quantitative grab sampling survey; covered both wet and dry seasons.
Six stations sampled in each of 10 locations. |
25 & 26 February, 5 & 6 July, 9
September and 8 November 2004, 23 September 2005 and 13 December 2005. |
Subtidal Hard Bottom Habitat (Coral) |
Quantitative (Rapid Ecological Assessment (REA) technique, a total of
eight 100 m transects at 5 locations) and qualitative (recorded within Study
Area and areas in the vicinity, 3 locations); covered wet season. |
9 & 15 May 2004, 29,30 September
& 3 October 2005. |
Marine Mammal |
Land-based visual survey during daytime, 5 days per month and 6 hours
per day, covered four seasons (12 months). |
13, 14, 21, 23 & 26 February, 8, 9, 10, 17 & 18 March, 16, 19,
20, 21 & 26 April, 10, 12, 14, 19 & 25 May, 10, 14, 17, 18 & 28
June 2004, 23, 26, 27, 28 & 29 July 2004, 25, 26, 27, 30 & 31 August,
6, 7, 13, 14 & 22 September 2004, 27, 28, 29, 30 & 31 October 2004,
16, 17, 24, 25 & 26 November 2004, 16, 21, 28, 30 & 31 December 2004,
10, 12, 14, 17 & 28 January 2005 |
|
Quantitative
vessel based survey using line transect methods spanning Hong Kong western
waters (Deep Bay, Southwest Lantau,Northwest Lantau and West Lantau) 3 days,
2 times per month |
18, 19, 20,21, 22, 25, 26, 27 July 2005,
3, 4, 5,15,24 & 25 August 2005, 5,7,15, 16 & 20 September 2005, 5, 6,
7, 17, 18 & 19 October 2005, 22, 24, 25, 28, 29 & 30 November 2005,
6,7,8 & 22 December 2005, 13, 16, 17, 19, 20 & 24 January 2006, 1, 2,
3, 7, 8 & 9 February 2006, 17, 23, 28, 29, 31 March 2006, 3, 6, 18, 25,
26, 27 April 2006, 2, 4, 8, 9, 10, 11 May 2006. |