Contents

1                      Introduction                                                                           

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                        

4                      Conclusion                                                                              

 

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:

¡P      Semi-quantitative Rapid Ecological Assessment (REA) survey; and

¡P      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 ¡V 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 ¡V 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 ¡V 3, where:

0 = no sediment;

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:

¡P      site (transect) information (Tier I and II data), depth and environmental descriptors; and

¡P      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 ¡V 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 ¡V 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 ¡V 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.

 


Table 3.1        Seabed Attributes along the REA Survey Transects

Zone

A

B

C

Depth Zone (a)

S1

S2

D1

D2

S1

S2

D1

D2

S1

S2

D1

D2

Depth (-m CD)

3-5

3-5

6-9

7-10

4-5

4-5

8-9

9-11

4-5

4-5

6-10

10-12

Seabed attributes (b)

 

 

 

 

 

 

 

 

 

 

 

 

Bedrock

0

0

0

0

0

0

0

0

0

0

0

0

Boulders ¡V large

5

5

3

1

5

4

2

4

3

3

1

0

Boulders ¡V small

3

3

2

1

1

3

4

2

4

4

1

1

Rock

1

1

1

1

1

1

1

0

1

1

0

0

Rubble

0

0

1

1

1

1

0

0

1

1

0

0

Sand

1

1

4

5

1

1

3

1

1

1

5

5

Silt

0

0

1

1

0

0

0

0

0

0

0

0

Ecological attributes (b)

 

 

 

 

 

 

 

 

 

 

 

 

Hard coral

1

1

1

1

1

1

1

1

1

1

1

1

Dead standing coral

0

0

0

0

0

0

0

0

0

0

0

0

Octocoral

1

0

0

1

0

1

0

0

0

0

1

1

Black coral

0

0

0

1

0

0

1

0

0

0

0

1

Turf algae

0

0

0

0

0

0

0

0

0

0

0

0

Macroalgae

0

0

0

0

0

0

0

0

0

0

0

0

Coralline algae

2

2

0

0

2

2

0

0

3

3

0

0

Notes:      

(a) S = shallow water; M = mid water; D=deep water

(b)       1=<5% Cover, 2= 6-10% Cover, 3 = 11-30% Cover, 4 = 31-50% Cover, 5 = 51-75%
Cover, 6 = 76-100% Cover.

Table 3.2        Seabed Attributes along the REA Survey Transects

Type

Taxon/ Family

Species

Zone

 

A

A

A

A

B

B

B

B

C

C

C

C

 

 

Depth (a)

S1

S2

D1

D2

S1

S2

D1

D2

S1

S2

D1

D2

Hard Coral

Acroporidae

Acropora pruinosa

0

0

0

0

1

1

0

0

0

0

0

0

 

 

Acropora solitaryensis

1

0

0

0

2

2

0

0

0

0

0

0

 

 

Montipora venosa

2

1

2

0

0

0

0

0

0

0

0

0

 

Coscinaraeidae

Coscinaraea sp.

0

0

1

0

0

0

0

0

0

1

1

0

 

Dendrophyllidae

Turbinaria peltata

1

0

0

0

0

0

0

0

0

0

0

0

 

 

Tubastrea/ Dendrophyllia sp.

0

0

0

1

1

0

0

0

0

0

0

1

 

Incertae sedis

Leptastrea pruinosa

1

0

0

0

0

1

0

0

0

0

0

0

 

 

Plesiastrea versipora

3

2

3

1

3

3

2

2

3

3

1

0

 

Lobophyllidae

Acanthastrea echinata

0

0

0

0

0

1

0

0

0

0

0

0

 

Merulinidae

Cyphastrea serailia

0

0

0

0

0

0

1

1

0

0

0

0

 

 

Favites abdita

0

0

0

0

0

1

0

0

0

0

0

0

 

 

Favites chinensis

2

0

0

0

0

0

0

0

0

0

0

0

 

 

Favites pentagona

2

0

0

0

1

0

0

0

0

0

0

0

 

 

Hydnophora exesa

0

0

0

0

0

0

0

0

1

0

0

0

 

 

Platygyra acuta

1

0

0

0

0

1

0

0

0

0

0

0

 

 

Astrea curta

0

0

0

0

0

1

0

0

0

0

0

0

 

Poritidae

Goniopora stutchburyi

1

0

2

0

0

0

1

1

1

0

1

0

 

 

Goniopora planulata

0

0

0

0

0

0

0

0

0

0

0

0

 

 

Porites sp.

2

1

2

0

3

3

1

1

3

0

1

0

 

Psammocoridae

Psammocora superficialis

1

1

3

0

1

0

1

1

1

1

1

0

 

 

Psammocora haimeana

0

0

1

0

0

0

0

0

0

0

0

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Octocoral

Acanthogorgiidae

Anthogorgia sp.

0

0

0

2

0

0

0

0

0

0

0

1

 

 

Muricella sp.

0

0

0

2

0

0

0

0

0

0

0

2

 

Alcyoniidae

Cladiella sp.

0

0

0

0

0

1

0

0

0

0

0

0

 

 

Paraminabea sp.

0

0

0

2

0

0

0

0

0

0

0

0

 

Nephtheidae

Dendronephthya sp.

2

0

0

0

0

2

0

0

0

0

0

0

 

 

Scleronephthya gracillimum

0

0

0

2

0

0

0

0

0

0

0

1

 

Plexauridae

Echinomuricea sp.

0

0

0

3

0

0

0

0

0

0

2

3

 

 

Euplexaura sp.

0

0

0

0

0

0

0

0

0

0

0

1

 

 

Menella sp. / Paraplexaura sp.

0

0

0

2

0

1

0

0

0

0

0

2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Black Coral

Antipathidae

Antipathes curvata

0

0

0

1

0

0

0

0

0

0

0

2

 

 

Cirrhipathes sp.

0

0

0

1

0

0

1

0

0

0

0

0

Notes:

(a) S = shallow water; M = mid water; D=deep water

(b) 1=Rare, 2= Uncommon, 3 = Common, 4 = Abundant, 5 = Dominant.

 


3.2                                   Results of Coral Colony Monitoring

Coral Colony Monitoring was undertaken at Zone A, Zone B and Zone C.  The monitoring area was the same as the REA survey area (Figure 3.1 ).  At Zone A, hard corals at -3 to -5 m CD and octocorals/ black corals at -9 to -12 m CD were selected for monitoring.  At Zone B, hard coral and octocoral colonies at -3 to -5 m CD were selected.  At Zone C, hard corals at ¡V4 to ¡V5 m CD and octocorals/ black corals at -10 to -12 m CD were selected for monitoring. 

The following data were collected for the selected hard coral, soft coral, black coral and gorgonian colonies and are summarized in Table 3.3 to 3.5:

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 (i.e. pale) and b. bleached (i.e. 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.

Photographic records of the selected coral colonies for coral colony monitoring are shown in Annex A.

In the Post Project Coral Survey, none of the hard coral colonies were observed with sediment cover at either of the two Monitoring Stations in Zone A and Zone B while two of 15 hard coral colonies at Zone C (Control Station) were observed with low sediment cover (1%).  Octocorals/black corals at all the stations (both Monitoring and Control) were free of sediments.  The health conditions of hard corals, octocorals and black corals were generally good without any bleaching or partial mortality recorded.

Comparing these data to the results recorded during the Baseline Monitoring  (which showed that one (1) out of 15 hard coral colonies observed at Zone B and seven (7) out of 15 hard coral colonies observed at Zone C had 1-5% sediment cover), less coral colonies were observed with sediment cover during the Post Project Monitoring.  The health conditions of hard corals, octocorals and black corals appeared not to be affected by the cable laying process.

Overall, the number of coral colonies observed with sediment cover was slightly reduced during the Post Project Coral Survey.  The health conditions of hard corals, octocorals and black corals were generally good with no bleaching or partial mortality recorded.  Thus, there did not appear to be any unacceptable impacts to the health conditions of coral colonies as a result of the cable installation works. 


Table 3.3        Species, Size, Sediment Cover, Bleached Area, Partial Mortality and Physical Damage to the Identified Coral Colonies in Zone A (Round Island)

Coral No.

Family

Genus

Species

Max. diameter (cm)

Max. height (cm)

Max. width (cm)

Sediment cover (%)

Sediment color

Sediment Texture

Sediment thickness (cm)

Bleached area (%)

Partial mortality (%)

Physical damage to colonies

Hard Corals

 

 

 

 

 

 

 

 

 

 

 

 

1

Psammocoridae

Psammocora

superficialis

15

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

2

Psammocoridae

Psammocora

superficialis

12

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

3

Psammocoridae

Psammocora

superficialis

20

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

4

Psammocoridae

Psammocora

superficialis

20

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

5

Psammocoridae

Psammocora

superficialis

50

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

6

Psammocoridae

Psammocora

superficialis

50

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

7

Psammocoridae

Psammocora

superficialis

40

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

8

Poritidae

Porites

-

40

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

9

Psammocoridae

Psammocora

superficialis

40

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

10

Psammocoridae

Psammocora

superficialis

35

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

11

Psammocoridae

Psammocora

superficialis

26

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

12

Poritidae

Porites

-

20

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

13

Incertae sedis

Plesiastrea

versipora

23

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

14

Incertae sedis

Plesiastrea

versipora

20

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

15

Incertae sedis

Plesiastrea

versipora

35

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

 

Octocorals/Black Corals

 

 

 

 

 

 

 

 

 

 

 

 

1

Nephtheidae

Dendronephthya

-

20

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

2

Plexauridae

Echinomuricea

-

N/A

12

5

None

N/A

N/A

N/A

N/A

N/A

N/A

3

Plexauridae

Echinomuricea

-

N/A

20

5

None

N/A

N/A

N/A

N/A

N/A

N/A

4

Plexauridae

Echinomuricea

-

N/A

20

10

None

N/A

N/A

N/A

N/A

N/A

N/A

5

Nephtheidae

Dendronephthya

-

10

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

6

Nephtheidae

Scleronephthya

gracillimum

N/A

25

15

None

N/A

N/A

N/A

N/A

N/A

N/A

7

Nephtheidae

Scleronephthya

gracillimum

20

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

8

Nephtheidae

Scleronephthya

gracillimum

20

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

9

Plexauridae

Menella/ Paraplexaura

-

N/A

20

25

None

N/A

N/A

N/A

N/A

5

N/A

10

Nephtheidae

Scleronephthya

gracillimum

25

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

11

Nephtheidae

Scleronephthya

gracillimum

35

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

12

Nephtheidae

Dendronephthya

-

25

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

13

Plexauridae

Echinogorgia

-

N/A

40

25

None

N/A

N/A

N/A

N/A

N/A

N/A

14

Acanthogorgiidae

Anthogorgia

-

N/A

10

10

None

N/A

N/A

N/A

N/A

N/A

N/A

15

Alcyoniidae

Paraminabea

-

25

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

 

 

 

Table 3.4        Species, Size, Sediment Cover, Bleached Area, Partial Mortality and Physical Damage to the Identified Coral Colonies in Zone B (Sung Kong)

Coral No.

Family

Genus

Species

Max. diameter (cm)

Max. height (cm)

Max. width (cm)

Sediment cover (%)

Sediment color

Sediment Texture

Sediment thickness (cm)

Bleached area (%)

Partial mortality (%)

Physical damage to colonies

Hard Corals

 

 

 

 

 

 

 

 

 

 

 

 

1

Poritidae

Porites

-

30

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

2

Siderastreidae

Psammocora

superficialis

18

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

3

Poritidae

Porites

-

40

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

4

Acroporidae

Acropora

valida

18

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

5

Acroporidae

Acropora

solitaryensis

45

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

6

Dipsastaea

Favites

pentagona

18

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

7

Incertae sedis

Plesiastrea

versipora

14

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

8

Dipsastrea

Leptastrea

pruinosa

15

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

9

Acroporidae

Acropora

solitaryensis

37

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

10

Dipsastaea

Favites

pentagona

23

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

11

Dipsastaea

Cyphastrea

serailia

17

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

12

Dipsastaea

Cyhastrea

serailia

35

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

13

Poritidae

Porites

-

45

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

14

Poritidae

Porites

-

50

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

15

Poritidae

Porites

-

30

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Octocorals/Black Corals

 

 

 

 

 

 

 

 

 

 

 

 

1

Nephtheidae

Dendronephthya

-

20

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

2

Nephtheidae

Dendronephthya

-

25

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

3

Nephtheidae

Dendronephthya

-

16

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

4

Nephtheidae

Dendronephthya

-

20

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

5

Nephtheidae

Dendronephthya

-

25

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

6

Nephtheidae

Dendronephthya

-

18

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

7

Nephtheidae

Dendronephthya

-

15

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

8

Nephtheidae

Dendronephthya

-

18

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

9

Nephtheidae

Dendronephthya

-

24

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

10

Nephtheidae

Dendronephthya

-

20

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

11

Nephtheidae

Dendronephthya

-

13

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

12

Nephtheidae

Dendronephthya

-

23

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

13

Alcyoniidae

Cladiella

-

N/A

26

20

None

N/A

N/A

N/A

N/A

N/A

N/A

14

Alcyoniidae

Cladiella

-

N/A

13

10

None

N/A

N/A

N/A

N/A

N/A

N/A

15

Nephtheidae

Dendronephthya

-

7

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

 

Table 3.5        Species, Size, Sediment Cover, Bleached Area, Partial Mortality and Physical Damage to the Identified Coral Colonies in Zone C (Po Toi)

Coral No.

Family

Genus

Species

Max. diameter (cm)

Max. height (cm)

Max. width (cm)

Sediment cover (%)

Sediment color

Sediment Texture

Sediment thickness (cm)

Bleached area (%)

Partial mortality (%)

Physical damage to colonies

Hard Corals

 

 

 

 

 

 

 

 

 

 

 

 

1

Siderastreidae

Psammocora

superficialis

30

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

2

Incertae sedis

Plesiastrea

versipora

40

N/A

N/A

1

Light yellow

Coarse

1 mm

N/A

N/A

N/A

3

Poritidae

Porites

-

40

N/A

N/A

1

Light yellow

Coarse

1 mm

N/A

N/A

N/A

4

Poritidae

Porites

-

50

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

5

Poritidae

Porites

-

35

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

6

Incertae sedis

Plesiastrea

Versipora

15

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

7

Dipsastaea

Leptastrea

pruinosa

60

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

8

Poritidae

Porites

-

50

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

9

Poritidae

Porites

-

35

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

10

Incertae sedis

Plesiastrea

Versipora

50

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

11

Poritidae

Porites

-

30

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

12

Poritidae

Porites

-

30

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

13

Incertae sedis

Plesiastrea

versipora

35

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

14

Poritidae

Porites

-

30

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

15

Poritidae

Porites

-

40

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

 

Octocorals/Black Corals

 

 

 

 

 

 

 

 

 

 

 

 

1

Plexauridae

Echinomuricea

-

N/A

10

5

None

N/A

N/A

N/A

N/A

N/A

N/A

2

Plexauridae

Echinomuricea

-

N/A

15

5

None

N/A

N/A

N/A

N/A

N/A

N/A

3

Plexauridae

Menella/ Paraplexaura

-

N/A

15

10

None

N/A

N/A

N/A

N/A

N/A

N/A

4

Plexauridae

Menella/ Paraplexaura

-

N/A

10

10

None

N/A

N/A

N/A

N/A

N/A

N/A

5

Plexauridae

Echinomuricea

-

N/A

20

10

None

N/A

N/A

N/A

N/A

N/A

N/A

6

Plexauridae

Echinomuricea

-

N/A

20

15

None

N/A

N/A

N/A

N/A

N/A

N/A

7

Antipathidae

Antipathes

curvata

N/A

30

60

None

N/A

N/A

N/A

N/A

N/A

N/A

8

Acanthogorgiidae

Anthogorgia

-

N/A

15

15

None

N/A

N/A

N/A

N/A

N/A

N/A

9

Plexauridae

Echinomuricea

-

N/A

20

15

None

N/A

N/A

N/A

N/A

N/A

N/A

10

Acanthogorgiidae

Muricella

-

N/A

30

30

None

N/A

N/A

N/A

N/A

N/A

N/A

11

Nephtheidae

Scleronephthya

gracillimum

25

N/A

N/A

None

N/A

N/A

N/A

N/A

N/A

N/A

12

Antipathidae

Antipathes

curvata

N/A

20

30

None

N/A

N/A

N/A

N/A

N/A

N/A

13

Antipathidae

Antipathes

curvata

N/A

30

50

None

N/A

N/A

N/A

N/A

N/A

N/A

14

Acanthogorgiidae

Muricella

-

N/A

15

15

None

N/A

N/A

N/A

N/A

N/A

N/A

15

Acanthogorgiidae

Anthogorgia

-

N/A

30

20

None

N/A

N/A

N/A

N/A

N/A

N/A


4                                          Conclusion

Post Project Coral Surveys were undertaken on 23 and 24 August 2018 at three designated zones (including two monitoring stations at Round Island and Sung Kong, and one control station at Po Toi) within one month after completion of the cable installation works in accordance with the EM&A Manual of the Project Profile.  During the Post Project Survey, REA surveys and Coral Colony Monitoring with the same methodology as the Baseline Coral Monitoring were conducted and the results were then compared between the two monitoring events.

Comparison of the REA results indicated that the conditions of coral communities were similar before and after cable installation works, with generally similar cover and composition of major abiotic and biotic attributes between the Baseline and Post Project Coral Monitoring Surveys.  Results of the Coral Colony Monitoring showed that the number of hard coral colonies with sediment cover slightly reduced during the Post Project Coral Survey compared to the Baseline Coral Monitoring Surveys.  The selected coral colonies generally did not exhibit any sign of bleaching, partial mortality or physical damage during both Baseline and Post Project Coral Monitoring Surveys, except 5% partial mortality observed on one (1) of the 15 octocoral colonies at Zone A and one (1) of 15 hard coral colonies at Zone B during the Baseline Coral Monitoring Survey.

Overall, there did not appear to be any unacceptable impacts to corals as a result of the PLCN cable installation works. 

 


 



 (1) DeVantier, L.M., G.De¡¦Ath, T.J. Done and E. Turak (1998). Ecological assessment of a complaex natural system: A case study from the Great Barrier Reef. Ecological Applications 8: 480-496.

 (2)   Fabricius, K.E. and D. McCorry. (2006). Changes in octocoral communities and benthic cover along a water quality gradient in reefs of Hong Kong. Marine Pollution Bulletin 52: 22-23.