Contents
1.1 Project Background
1.2 Objective of the Post Project
Coral Survey
1.3 Purpose of this Report
1.4 Structure of the Report
2 Post Project
Coral Survey Methodology
2.1 Monitoring Locations
2.2 Monitoring Methodology
3 Post Proejct
Coral Survey Results
3.1 Results of REA Survey
3.2 Results of Coral Colony
Monitoring
Figures
Figure 1.1 Proposed PLCN Submarine Cable System
Figure 2.1 Locations of the Baseline and Post Project Coral
Monitoring
Figure 3.1 Locations of REA
Surveys
ANNEX
Annex A Photographic Results of Selected Coral Colonies in Zones A, B & C
for Coral Colony Monitoring
1
Introduction
1.1
Project Background
In order to help meet the tremendous telecommunication services
requirements between Asia and North America, the PLCN Consortium has decided to build a submarine telecommunication
cable system, which will be approximately 12,800 km in length, connecting HKSAR
and the United States.
The cable will connect to Deep Water Bay (DWB) within the HKSAR. PCCW
Global (HK) Limited is providing the cable landing point and the associated
cable landing service in HKSAR for the PLCN Consortium.
The route of the PLCN submarine cable system is depicted in Figure 1.1.
The cable will land at an existing manhole location at DWB.
DWB is currently the landing site for a number of submarine
cables.
The cable will travel from DWB southward approaching the East Lamma
Channel. Near to Round Island, the
cable is approximately parallel to the East Lamma Channel until the south of
Stanley Peninsula. The cable will
then travel eastward to the boundary of HKSAR waters and will enter the South
China Sea.
The PLCN submarine cable in HKSAR waters has a target burial depth of 5
m below the sea bed in the HKSAR waters.
The total length of the submarine cable within HKSAR waters is
approximately 40 km.
The cable laying process only required minor works within the marine
environment. The landing is
situated to the far northwest end of the Deepwater Bay, away from the shark
preventive net swimming area. Only
small scale construction works were required at the cable landing site to
enable the cable to enter the existing Beach Manhole (BMH) system.
1.2
Objective of the Post Project
Coral Survey
A Project Profile (PP-550/2017), which includes an
assessment of the potential environmental impacts associated with the
installation of the PLCN-Deep Water Bay submarine telecommunications cable
system within HKSAR, was prepared and submitted to the Environmental Protection
Department (EPD) under section 5(1)(b) and 5(11) of the Environmental Impact Assessment Ordinance (EIAO) for the
application for Permission to apply directly for Environmental Permit
(EP). The EPD subsequently issued
an Environmental Permit (EP- 529/2017) for the
Project in July 2017.
In accordance with the Environmental
Monitoring & Audit (EM&A) Manual appended with the approved Project Profile, a Post Project Coral
Survey should be conducted within one month after the completion of the cable
installation. During the Post
Project Survey, data were collected at the same locations and using the same
methodology as the Baseline Monitoring Survey for REA surveys and Coral Colony
Monitoring (noting qualitative spot dive surveys were not required).
1.3
Purpose of this Report
This Post Project Coral Survey Report (“the Report”) is prepared by
ERM-Hong Kong, Limited (ERM) on behalf of PLCN Consortium to present the
methodology and findings of the Post Project Coral Survey for the Project in
accordance with requirements of the EM&A
Manual appended with the approved Project
Profile.
The objective of the Post Project Coral Survey is to provide data for
comparison with the data collected during the baseline monitoring from the same
locations. The comparison of
baseline and post Project data is used to determine any observable impacts to
corals as a result of the cable installation works.
1.4
Structure of the Report
The remainder of the report is structured as follows:
Section 2: Post Project Coral Survey Methodology
Presents the post project coral survey methodology,
parameters monitored, monitoring locations and depth, monitoring date, time,
frequency and duration in accordance with the EM&A Manual.
Section 3: Post Project Coral Survey Results
Summarizes the post project coral survey results
according to the stipulated monitoring methodology, in accordance with the EM&A Manual.
Section 4: Conclusion
Provides comments and a conclusion based on the
findings from the Post Project Coral Survey of the Project.
2
Post Project
Coral Survey Methodology
2.1
Monitoring Locations
Coral monitoring was
undertaken at Round Island and Sung Kong (Monitoring Stations), and a Control Station at Po Toi which is located more than 1
km from the cable alignment and thus unlikely to be impacted by cable
works. The monitoring locations are
shown in Figure 2.1 and
detailed below:
Monitoring
Stations:
§ Zone A: Round
Island; and
§ Zone B: Sung Kong.
Control Station:
§ Zone C: Po
Toi.
At each monitoring station,
coral monitoring was undertaken in two depth zones (ie shallow water: -2 to -5
mCD and deep water: -5 to -15 mCD), with minor revisions to the depth ranges
based on observations of coral distribution during surveys.
2.2
Monitoring Methodology
2.2.1
Monitoring Personnel
The coral monitoring works
were undertaken by qualified coral specialists hired by the ET, degrees in
marine sciences and with at least three years of post-graduate experience in
the field of marine ecology and undertaking coral surveys. The same core team of coral specialists
were used for these dive surveys as for the Baseline surveys, to maintain
consistency in the documentation of the coral condition and all personnel have
all been approved by AFCD in advance of undertaking the work.
2.2.2
Survey
Methodology
The Post Project Coral Survey
comprised the following two components:
·
Semi-quantitative
Rapid Ecological Assessment (REA) survey; and
·
Coral
Colony Monitoring.
Survey methodology of the two
components is described below.
Rapid
Ecological Assessment
(REA) Survey Method
A standardised
semi-quantitative REA survey technique was used to investigate the general
conditions of the coral communities (hard, soft and black corals) associated
with subtidal hard bottom habitats at the Monitoring and Control Stations. The collection of REA data during the
Post Project Surveys allowed for a comparison of coral conditions before and
after cable installation works in order to determine any changes in conditions
due to the works.
The REA technique allows
semi-quantitative information on the ecological attributes of the subtidal
habitat to be obtained in a relatively simple way without compromising
scientific rigour. This technique
is the standard practice for EIA marine baseline surveys in HKSAR and has been
modified from the standardised REA survey technique established for the
assessment of coral communities on the Great Barrier Reef ([1])
for marine environment of HKSAR ([2]).
A series of REA surveys were
conducted by qualified coral specialists using SCUBA at the Monitoring stations
(Round Island and Sung Kong; Figure 2.1) and Control
Station (Po Toi; Figure 2.1) with the aim
of recording the condition of substratum, estimating the diversity and relative
abundance of coral assemblages (ie hard corals, octocorals and black corals)
and for all hard coral colonies identification to species level, while for
octocorals and black corals recorded, identification to genus level. The surveys were undertaken on REA
transects laid onto the seabed, each of which measured 100 m in length, at
the following two depth zones of each station:
Ÿ Shallow depth region:
typically the depth range of hard coral colonies associated with subtidal hard
bottom habitat is -2 to -5 m CD but may be adjusted based on the qualitative
spot dive survey during the Baseline Survey and observations of coral
distribution during the surveys); and
Ÿ Deep depth region: typically
-5 to -15 m CD but may be adjusted based on observations of coral distribution
during the surveys).
The location of the REA
transects as well as the depth ranges of the monitored depth zones were
determined based on findings from the qualitative spot dive survey during the
Baseline Survey. A total of two (2)
REA transects were monitored at each depth region of Round Island, Sung Kong and
Po Toi.
Following the laying of the
transect line, the coral specialists swam along the transect slowly and
conducted the REA survey. The REA
methodology encompassed an assessment of the benthic cover (Tier I) and taxon
abundance (Tier II) undertaken in a swathe approximately 2 m wide, 1 m either
side of each transect according to the reduced underwater visibility. An explanation of the two assessment
categories (Tiers) used in the survey is presented below.
Tier I – Categorisation of
Benthic Cover
Upon the completion of each survey
transect, ecological and substratum attributes were assigned to standard ranked
(ordinal) categories (Tables 2.1 and 2.2).
Table 2.1 Tier
I Benthic Attribute Categories
|
Ecological
Attributes |
Substratum
Attributes |
|
Hard coral |
Bedrock |
|
Dead standing coral |
Continuous pavement |
|
Octocoral (Soft corals and Gorgonians) |
Rocks (<26 cm) |
|
Black coral |
Large boulders (>50 cm) |
|
Macroalgae |
Small boulders (<50 cm) |
|
Other Benthos (including sponges, zoanthids,
ascidians and bryozoans) |
Rubble |
|
|
Sand |
|
|
Mud/ Silt |
|
|
Other |
Table
2.2 Tier
I Ordinal Ranks of Percentage Cover of Benthic Attributes
|
Rank |
Percentage Cover (%) |
|
0 |
None
recorded |
|
1 |
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 for each transect.
Taxa were identified in situ
to the following levels:
§ Scleractinian (hard) corals
to species wherever possible;
§ Octocorals, black corals, anemones
and conspicuous macroalgae recorded according to morphological features and to
genus level where possible; and
§ Other benthos (including
sponges, zoanthids, ascidians and bryozoans) recorded to genus level, where
possible, or phylum plus growth form.
Following the completion of the survey
of each transect, each taxon in the inventory was ranked in terms of abundance
in the community (Table 2.3). 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.
Representative photos of organisms were taken as presented in the
results.
Table 2.3 Ordinal
Ranks of Taxon Abundance
|
Rank |
Abundance |
|
0 |
Absent |
|
1 |
Sparse (a) |
|
2 |
Uncommon |
|
3 |
Common |
|
4 |
Abundant |
|
5 |
Dominant |
|
Note: (a) The
classification of “sparse” abundance refers to low abundance (small quantity)
on the transect, rather than in terms of distribution in HKSAR waters. |
|
A set
of environmental site descriptors were also recorded for each REA transect as
follows:
(A)
The
degree of exposure to prevailing wave energy ranked from 1 - 4, where:
1 = sheltered (highly protected by topographic
features from prevailing waves);
2 = semi-sheltered (moderately protected);
3 = semi-exposed (only partly protected); and
4 = exposed (experiences the full force of
prevailing wave energy).
(B)
Sediment
deposition on the reef substratum (particle sizes ranging from very fine to
moderately coarse) rated on a four point scale, from 0 – 3, where:
1 = minor (thin layer) sediment deposition;
2 = moderate sediment deposition (thick layer), but substrate can be
cleaned by fanning off the sediment; and
3 = major sediment deposition (thick, deep layer), and substrate cannot
be cleaned by fanning.
During the REA survey, the
field data were recorded by an observer experienced in the underwater
identification of sessile benthic taxa (coral specialist), swimming along
identified sections of coastline on SCUBA from haphazardly-chosen starting
points. REA surveys were carried
out using 100 m long transect with the transect tapes laid out within a
single ecological zone - habitat - depth range. A suite of representative photographs
were captured for each REA transect.
All field data were checked
upon completion of each REA transect and a dive survey proforma sheet was
completed at the end of the fieldwork day.
Upon completion of the fieldwork, photographs were compiled for each
transect. Photographs for each REA
transect were then reviewed and REA data verified.
Once the transect photographs
had been reviewed and REA data checked, all data were inputted and stored in
Excel spreadsheets. Two
spreadsheets were used and data separated into:
·
site
(transect) information (Tier I and II data), depth and environmental
descriptors; and
·
species
abundance data for each transect.
Coral Colony Monitoring
Coral colony monitoring was
undertaken during the Post Project Surveys to identify any evidence of sediment
stress to corals before and after cable installation works. At each coral monitoring station, a
total of fifteen (15) hard coral colonies and fifteen (15) octocoral/black
coral colonies were selected for monitoring. Priority was given to selecting colonies
of horizontal plate-like and massive growth forms which present large stable
surfaces for the interception and retention of settling solids. Each of the selected corals were
identified to species or genus levels and photographed. The following data were collected:
Ÿ Maximum diameter of the
identified hard coral and soft coral colonies;
Ÿ Maximum height and width of
the identified gorgonians and black corals;
Ÿ Percentage of sediment cover
on the identified colonies and the colouration, texture and approximate
thickness of sediment on the coral colonies and adjacent substrate. Any contiguous patches of sediment cover
>10 % were recorded;
Ÿ Percentage of bleached area
on the identified colonies of which two categories were recorded: a. blanched
(ie pale) and b. bleached (ie whitened);
Ÿ Percentage of colony area
showing partiality mortality; and
Ÿ Physical damage to colonies,
tissue distension, mucous production and any other factors relevant were noted
in the field.
The coral colony monitoring
exercise was undertaken to ensure colonies of similar growth forms and size
were selected for the Post Project Monitoring as had been for the Baseline
Monitoring Although coral tagging
is a common practice for repeated monitoring of an individual colony, this
technique was not employed in this monitoring programme due to difficulties in
locating the tagged corals given the generally low visibility in the area and
low light conditions in deep water.
3
Post Proejct
Coral Survey Results
The Post Project Coral Survey was conducted over two days on 23 and 24
August 2018. The weather condition
was sunny on both days. Slight to
moderate swell was present in the sea on the two survey days. The underwater visibility generally
ranged between 1 to 2 m.
3.1
Results of REA Survey
The seabed composition
along each transect within Zone A, Zone B and Zone C are shown in Tables 3.1 - 3.2. Locations of the REA survey are
presented in Figure 3.1.
3.1.1
Zone A – Round Island
The seabed at the REA survey area of Zone A was predominately composed
of boulders in shallow depth region (-3 to -5 m CD) while at deep depth region
(-6 to -12m CD) the seabed was also mainly composed of sand and boulders.
Cover of hard corals was less than 5% in both the shallow and deep
water, with 13 hermatypic and one (1) ahermatypic hard coral species
recorded. Octocoral community was
only found at the shallow water of transect 1 and deep water of transect 2 and
black coral was only observed in the deepwater of transect 2. A total of seven (7) species of
octocorals and two (2) species of black corals were recorded during REA survey. Plesiastrea
versipora and Echinomuricea sp.
was the dominant hard coral and octocoral species found in the region,
respectively.
3.1.2
Zone B – Sung Kong
The seabed was predominately composed of bedrocks in both shallow (-4 to
-5 m CD) and deep (-8 to -11 m CD) depth zones.
A total of 13 hermatypic hard coral species were recorded in shallow
depth zone along the two transects of the coast of the zone. In the western coast of Zone B, one (1)
ahermatypic hard coral species was recorded in shallow depth zone and one (1)
black coral species was recorded in deep depth zone. Whilst three (3) species of octocorals
were only recorded in the eastern coast of the zone and their abundance was
low. The dominant species in Zone B was
hard coral Plesiastrea versipora and Porites sp.
3.1.3
Zone C – Po Toi
The seabed in the shallow (-4 to -5 mCD) and deep (-6 to -12 m CD) depth
zones of Zone C were predominately composed of boulders and sand,
respectively.
Hard coral community was recorded in both shallow and deep depth zones
with six (6) hermatypic hard coral
species and one (1) species of
ahermatypic hard coral species recorded.
Octocorals and black coral were only observed in the deep depth zone
(beyond -6 m CD) with six (6) species of octocoral and one (1) species of black
coral. Hard coral Plesiastrea versipora and Porites sp. were dominant on the hard substratum along all transects and
octocoral, Echinomuricea sp.were commonly observed in the deep water of transect 2.
Overall, comparing the REA result from the Post Project Coral Survey
with that from the Baseline Coral
Survey, the composition and coverage of major abiotic and biotic attributes in
all three zones are similar. The
species composition is also similar between the Baseline and Post-Project
monitoring, except 2-3 more coral species were recorded in all the sites during
the post Project coral monitoring than had been recorded during Baseline
monitoring.