Executive summary

 
• A subtidal survey carried out in 1998 with the use of an ROV showed that the proposed reclamation site and adjacent seawall of the ash lagoon supported an abundant assemblage of soft corals and gorgonians. The soft coral assemblage comprised a high abundance of sea whips (Euplexaura sp.) and soft corals (Dendrophthya sp.).

   

• A baseline seabed survey detailing the soft coral assemblages was subsequently carried out and the results are herein reported upon. Three zones, i..e., Reclamation Site, Ash Lagoon Seawall and Ash Lagoon Base Zones, were identified for ecological assessment and a Rapid Ecological Assessment (REA) methodology used to describe and quantitatively document the soft coral assemblages of each zone.

   

• Soft corals and gorgonians were predominately recorded on hard substrate, particularly boulders, at a depth of between -8 to -11 m C.D. within each zone. A total of nine gorgonian species from three genera, i.e., Euplexaura, Echinogorgia and Muricella were recorded, five species of soft corals from the genera Dendronephthya, Scleronephthya and Alcyonium and one sea pen species, Virgularia were also recorded. Two genera of ahermatypic corals were recorded, i.e., Tubastrea and Dendrophyllia.

   

• The soft coral abundance within each zone was:

 
1. The Ash Lagoon Seawall Zone = 10.076 ± 4.949 colonies. m^-2.

    

2. The Ash Lagoon Base Zone = 4.558 ± 1.897 colonies. m^-2.

    

3. The Reclamation Site Zone = 2.682 ± 2.526 colonies. m^-2.

 
• The soft coral assemblages of all three zones all possessed a high abundance of one particular whip coral species (Euplexaura sp.) and the highest numbers were recorded within the Ash Lagoon Seawall Zone (9.922 ± 4.166 colonies. m^-2).

   

• Field observations and recorded video footage of the area suggest that the availability of hard substrate and particle transport for soft coral suspension feeding by strong tidal currents were important physical parameters for the establishment of the soft coral assemblages recorded for the subtidal areas in the vicinity of the power station.

1. Introduction

Baseline marine ecological monitoring was required to establish the status of scleractinian and soft coral assemblages prior to the commencement of the reclamation works which are part of the proposed Lamma Power Station Extension. One area in the vicinity of the power station was identified for survey assessment prior to the present study as the seabed at this location was to be permanently lost due to the reclamation associated with the proposed extension works. The Reclamation Site Zone (Fig. 1) was evaluated in terms of ecological status using comprehensive surveys conducted with a Remotely Operated Vehicle (ROV). The surveys revealed a localised assemblage of soft corals and gorgonians at a distance of ~ 50-100 m to the south and west of the seawall of the ash lagoon (Fig. 1) (ERM 1999). The subtidal assessment carried out in 1998 resulted in the compilation of an extensive database on the abundance and diversity of the soft coral and gorgonian assemblages in the vicinity of the power station and it was concluded that the proposed reclamation site and adjacent seawall of the ash lagoon supported an abundant assemblage of gorgonians and soft corals, particularly common were sea whips (Euplexaura spp.) and soft corals (Dendronphthya spp.). The presence of the soft coral assemblage was thought to be in part due to the lack of trawling by fishing vessels in this area (ERM 1999).

In order to update this baseline information a detailed evaluation of the subtidal areas in the reclamation site and adjacent seawall and base were carried out. The main objectives of the baseline monitoring survey were (1), describe and quantitatively document the soft coral assemblages of three identified zones, i.e., Reclamation Site Zone, Ash Lagoon Seawall Zone and Ash Lagoon Base Zone; and (2), for subsequent use of data during Post-Construction Monitoring to ascertain the extent of recolonisation of soft corals adjacent to the Reclamation Site Zone, and the extent of colonisation on the rubble mound seawalls.

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 2. Methodology

The baseline monitoring consisted of subtidal dive surveys in the proposed Reclamation Site Zone and the adjacent Ash Lagoon Seawall and Ash Lagoon Base Zones (Fig. 1). It should be noted that the methodology was a variation from that specified in the EIA Report (ERM 1999) and agreement was given by the Agriculture, Fisheries and Conservation Department, Hong Kong SAR Government prior to the commencement of the surveys. The dive surveys were conducted by local experienced coral specialists over a three day period (21-22 and 23 November 2000).

2.1. Baseline Survey

In the EIA Report (ERM 1999), it was recommended that an ROV should be used for the baseline survey and the exact methodology presented in the EIA was to be followed. The ROV that was used to conduct the original survey as part of the EIA, however, was no longer available and a revised methodology for the baseline dive survey using SCUBA was used.

Quantitative dive surveys were undertaken within three zones as indicated in Figure 1. These zones were termed Reclamation Site Zone, Ash Lagoon Seawall Zone and Ash Lagoon Base Zone. Details of the location of each transect with Global Positioning System (GPS) is presented in Appendix 1.

1. Reclamation Site Zone

Within the Reclamation Site Zone ten randomly placed 100 m transects (Fig. 2) were surveyed to assess hard and soft coral coverage using the Rapid Ecological Assessment methodology adapted from DeVantier et al. (1998). A measuring tape was laid down in the middle of each transect and an area 0.5 m wide either side of the tape surveyed for it's entire length. This resulted in a "belt" transect. Photographs of representative coral species located within the belt transect were taken using either a Nikon F90 in an underwater Ikelite housing, a Kodak DC290 for general landscape shots or a Sony DSC-F505 for wide-angle and macro with strobes and video lights. Each transect was also videoed, with each transect filmed at approximately 50 cm above the transect tape and at a constant speed in compliance with standard protocols for coral surveys (no more than 10 metres per minute). The video camera was held at a 45° angle to provide a landscape view of the survey area as observed by the surveyors and provided a permanent record of the site. Video footage was only used to confirm the composition of epifauna on each transect and not used for data analyses.

2. Ash Lagoon Seawall Zone

Five permanently marked 100 m transects were surveyed (Fig. 2). Each transect within the Ash Lagoon Seawall Zone was placed on the seawall and marked with a steel stake inserted into the wall and the start and end locations noted by shoreline features and handheld Global Positioning System (GPS). A reconnaissance dive survey prior to the baseline surveys revealed no hermatypic scleractinian assemblages on the Ash Lagoon Seawall Zone and so instead of a quantitative video transect technique the REA methodology as carried out for the Reclamation Site and Ash Lagoon Base Zones was employed. Representative photos of soft corals and ahermatypic corals were taken.

3. Ash Lagoon Base Zone

Since the establishment of permanent markers in the sand substratum were not feasible five, randomly place 100 m transects were established in line with the seawall transects (Fig. 2) and the Rapid Ecological Assessment methodology used to assess coverage of soft corals and other epifauna. Each transect was videoed as for the Reclamation Site Zone and Ash Lagoon Seawall Zone and photographs taken of representative soft coral species.

2.1.1. Rapid Ecological Assessment methodology

Data were recorded by observers experienced in the field identification of sessile benthic taxa, swimming down-current along selected areas using scuba gear. Ten 100 m transects were surveyed. Start- points of transects were determined with a portable Global Positioning System (GPS) unit. A dive survey before the actual gathering of quantitative data revealed the predominance of soft corals on hard substrate in each zone. The use of a side-scan sonar map of the Reclamation Site Zone provided by Hong Kong Electric Co. Ltd. in a report of the geo-physical surveys (EGS 2000) aided the location of scattered hard substrate areas and these were targeted for transect placement with the use of GPS within this zone.

A 100 m transect was laid out and an assessment of the benthic cover (tier I) and taxon abundance (tier II) in a swathe ~ 1 m wide, 0.5 m either side of each transect complimented with landscape photographs (dependent on visibility) were then carried out. The transect survey was then completed by video footage taken of the epifauna along the transect. Due to the extremely low visibility encountered during the survey period the belt transect was reduced to a width of 0.5 m either side of the transect. Torches and powerful underwater strobes were employed for all survey collection dives, video footage and photography. Even using this method the two outer transects of the Reclamation Zone were not recorded by video due to strong currents disturbing seabed sediment.

Tier I: Categorisation of benthic cover

At the completion of each transect, six ecological and seven substratum attributes (Table 1a) were assigned to one of six standard ranked (ordinal) categories (Table 1b).

Table 1. Categories used in the surveys: (a) benthic attributes, (b) ordinal ranks of percentage cover.

Tier II: Taxonomic inventories to define types of benthic communities

An inventory of benthic taxa was compiled during each swim (transect). Taxa were defined in situ to the following levels: (1.) Scleractinian corals to species wherever possible. (2.) Soft corals, anemones and conspicuous macro-algae were identified to genus. (3.) Other benthos (including sponges, zoanthids, ascidians and bryozoans) were identified to genus level wherever possible but more typically to phylum plus growth form. At the end of each swim, each taxon in the inventory was ranked in terms of abundance in the community (Table 2). 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 2. Ordinal ranks of taxon abundance

2.1.2. Data compilation and analyses

Data on percentage cover and colony abundance of soft corals and gorgonians, were extracted from (1), dive surveys on the belt transects for all three zones, i.e., the Reclamation Site Zone and Ash Lagoon Seawall Zone and Ash Lagoon Base Zone. The REA methodology employed for soft coral surveys allowed for the presentation of abundance as (1), individual colony counts of soft corals and gorgonian species recorded, (2), a ranked ordinal category assignment based on the counts of individual organisms, i.e., soft corals and gorgonians and (3), a percentage cover estimate of ecological and substratum attributes.

The results are presented for each zone with a mean number of soft corals and gorgonians per m². Total and partial mortality of the dominant gorgonian (Euplexaura sp.) were also recorded along transects carried out within each survey zone.

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3. Results

3.1. Substratum attributes

Details of the substratum composition of the individual transects within each surveyed zone is presented in Appendix 2, section C. The Reclamation Zone was comprised of a fine, soft sand sediment (~ 90 % cover) with scattered small boulders (0-10 % cover) on the majority of transects. Transects eight and ten possessed 100 % fine, soft sand sediment. Construction debris including discarded metal structures, e.g., scaffolding, and pipes were recorded on several transects (particularly transect five). Transect five possessed a higher coverage of boulders (11-30 % cover). The base of the Ash Lagoon Seawall Zone consisted of large boulders with scattered sand patches. The five transects were comprised of ~ 90 % boulder cover with 0-10 % sand cover. The Ash Lagoon Base Zone located ~ 10-20 m distance from seawall comprised of fine, soft sand sediment (~ 90 % cover) with scattered small boulders and rocks (0-10 % cover). Exceptions were transects TA2 which had a higher boulder coverage (11-30 % cover) and TD2 with 100 % sand cover.

3.2. Ecological attributes

The three zones, i.e., Reclamation Site, Ash Lagoon Seawall and Ash Lagoon Base Zones, were all composed of soft coral assemblages generally associated with the hard substratum. Details of the general epifaunal composition of each transect for each zone is presented in Appendix 2, section B. The Reclamation Site Zone contained the lowest estimated percentage cover of soft corals (the majority of transects = 0-10 % cover), with the Ash Lagoon Base Zone consisting of intermediate soft coral coverage (all transects = 11-30 % cover) and the Ash Lagoon Seawall Zone possessing the highest percentage cover of soft corals (all transects = 31-50 % cover). The soft coral coverage of each zone was concentrated on boulders and other hard substrate such as the discarded metal structures, although a number of soft coral colonies were recorded on the sand seabed for the Ash Lagoon Seawall and Base Zones. Ahermatypic corals, e.g., Tubastrea sp., were also recorded on the boulders within the Reclamation Site and Ash Lagoon Seawall Zones.

A total of three soft coral genera from one family Alcyoniidae, three gorgonian genera from two families Acanthogorgiidae and Plexauridae and one seapen genus from the family Virgulariidae were recorded from the three zones (Table 1). A total of 16 species including soft and ahermatypic corals was recorded for the Reclamation Site Zone, 12 species for the Ash Lagoon Seawall Zone and 11 species for the Ash Lagoon Base Zone (Table 2).

Table 1. A list of soft coral, gorgonian and sea-pen families and genera recorded for all survey zones.

Table 2. Species list for each survey zone recorded at the Lamma Power Station

3.2.1. Soft coral, gorgonian and ahermatypic coral abundance

1. Reclamation Site Zone

   Azooxanthellate ocotocorals (gorgonians) were an abundant component of the soft coral assemblage of the Reclamation Site Zone. Table 3 shows the total species richness and mean density (number of colonies. m^-2) for each species of gorgonian, soft coral, sea pen and ahermatypic coral recorded and the total density of soft corals (including gorgonians) was 2.682 ± 2.524 colonies. m^-2. One species of gorgonian (Euplexaura sp. a white whip coral) (Section 6: Colour Plates 1-3) was the most abundant component of the epifaunal assemblage recorded in this zone with a mean density of 2.600 ± 1.106 colonies. m^-2. Records of the soft corals Scleronephthya sp. (Section 6: Colour Plate 9) and Alcyonium sp. (both of low density and percentage cover, i.e., =/<0.005 m^-2 and <10 %) in addition to the one record of the ahermatypic species Dendrophyllia sp. were made in this zone and the total species richness =16 species. The colony counts of all soft coral organisms and ahermatypic corals are presented in Appendix 3. The estimated percentage cover of each species based on recorded abundance is presented in Section A, Appendix 2 and again shows the common occurrence of the gorgonian Euplexaura sp.

2. Ash Lagoon Seawall Zone

   Azooxanthellate ocotocorals (gorgonians) were the main composition the soft coral assemblage of the Ash Lagoon Seawall Zone. Table 4 shows the total species richness and mean density (number of colonies. m^-2) for each species of gorgonian, soft coral and ahermatypic coral recorded. The total density of soft corals (including gorgonians) was 10.076 ± 4.949 colonies. m^-2. One species of gorgonian (Euplexaura sp. a white whip coral) was of high abundance and the main component of the epifaunal assemblage recorded in this zone (9.922 ± 4.166 colonies. m^-2). Field observations revealed that the occurrence of soft corals was primarily concentrated on the available hard substratum, i.e., boulders, suitable for coral settlement and growth. No sea pens were recorded within this zone. Soft corals (Dendronephthya spp.) were recorded (Table 4) and the majority of colonies recorded exhibited signs of sub-lethal stress in the form of bleaching and a general unhealthy appearance (Section 6: Colour Plates 7 and 8). The ahermatypic coral Tubastrea sp. was also recorded within this zone (Section 6: Colour Plates 10 and 11). The estimated percentage cover of each species based on recorded abundance is presented in Section A, Appendix 2 and again shows the high abundance of the Euplexaura sp.

3. Ash Lagoon Base Zone

Azooxanthellate ocotocorals (gorgonians) were the most abundant component of the soft coral assemblage of the Ash Lagoon Base Zone. Table 5 shows the total species richness and mean density (number of colonies. m^-2) for each species of gorgonian, soft coral and ahermatypic coral recorded and a total density for the soft corals (including gorgonians) of 4.558 ± 1.897 colonies. m^-2 was recorded. One species of gorgonian (Euplexaura sp. a white whip coral) was the main component of the soft coral assemblage recorded in this zone (4.496 ± 1.869 colonies. m^-2). No ahermatypic corals were recorded within this zone. The estimated percentage cover of each species based on recorded abundance is presented in Section A, Appendix 2 and again shows the common occurence of the Euplexaura sp.

Table 3. Total species richness and density (number of colonies. m^-2 ± S.E.) for each genus of soft coral, gorgonian, sea pen and ahermatypic coral for the Reclamation Site Zone.

Colour plates of the common soft corals, gorgonians are shown in Section 6.

Table 4. Total species richness and density (number of colonies. m^-2 ± S.E.) for each genus of soft coral, gorgonian, sea pen and ahermatypic coral for the Ash Lagoon Seawall Zone.

Table 5. Total species richness and density (number of colonies. m^-2 ± S.E.) for each genus of soft coral, gorgonian, sea pen and ahermatypic coral for the Ash Lagoon Base Zone.

Whole colony mortality for the abundant white whip coral (Euplexaura sp.) was recorded within each survey zone. Total mortality was highest for the Ash Lagoon Seawall Zone and Ash Lagoon Base Zone with a mean number of dead colonies of 24.00 ± 18.28 and 23.00 ± 6.78 per 100 m², respectively. The lowest total mortality was recorded for the Reclamation Site Zone (7.60 ± 9.51 colonies). Both large adult and juvenile colonies were affected.

Partial mortality was a common observation for the large adult white whip coral colonies within each survey zone (Section 6: Colour Plate 12). Partial mortality was lowest for the Ash Lagoon Base Zone with 16.00 ± 8.00 % of the total number of colonies exhibiting 0-30 % partial mortality of the upper branches and bases. One reason for the partial death of colonies was possibly due to the strong current and wave motion, which caused colonies upper branches to drag across the sand seabed either smothering and/or abrading polyps. The recorded partial mortality of the dominant white whip coral within the Reclamation Site Zone comprised 19.50 ± 16.80 % of total colonies with 0-30 % partial death particularly affecting the bases and upper branches and 7.00 ± 15.52 % of total colonies with 31-60 % partial death and again affecting the bases, and upper and lower branches. Sediment accumulation appeared to be a plausible reason for the die-off of tissue at the bases of colonies. Highest partial mortality was recorded within the Ash Lagoon Seawall Zone with 30.00 ± 17.89 % of total number of colonies recorded with 0-30 % partial death affecting bases and upper branches. Remnants of discarded gill nets, rubbish and accumulated sediment appeared to be the main reasons for the tissue die-off and a causative factor contributing to the partial death of Euplexaura sp. within the Ash Lagoon Base Zone. Seven gill nets were encountered in a 500 m stretch of shoreline at the Ash Lagoon Seawall Zone and four fishing boats worked this area in one day. Gill net fishing activity appeared to be high within this zone given the observations made in the three days of field work

3.2.3. Records of fish life within the three surveyed zones

Underwater visibility was poor throughout the dive surveys and few fish were observed. General observations are made, however, no quantitative data are presented as this was not part of the survey. The majority fish were observed along the Ash Lagoon sea wall and around patches of boulders out from the sea-wall and on the sea-bed in the area to be reclaimed, i.e., wherever there was hard substrate. Such fish included Chinese demoiselle (Neopomacentrus bankieri), Marbled rockfish (Sebastisicus marmoratus) and Weedy stingfish (Scorpaenopsis cirrhosa), all common local reef species. Two species of commercial importance were also observed, a 30 cm length Yellowfin seabream (Acathopagrus latus) and a number of sub-adult Yellow grouper (Epinephelus awoara). Juveniles of the latter species often inhabit isolated boulders and other hard substrate in predominantly sandy, silty areas in the depth range 5 ?10 m, a common substrate around the power station. The only fish observed to specifically use soft corals as shelter were juvenile Threadsail filefish (Stephanolepis cirrhifer), which were fairly abundant. A number of fishes which predominantly inhabit soft substrata, including gobies and sillagos were observed but could not be identified to species. A single individual of the rare sandperch Parapercis sexfasciatus and moray eel (Gymnothorax reticularis) were also seen.

3.2.4. Abundance of other epifaunal organisms

Encrusting sponges were recorded on boulders within the three survey zones, particularly an unidentified white encrusting sponge (Section 6: Colour Plate 13). Percentage cover was estimated to be between 11-30 % (Appendix 2, section A). The sea cucumber Colochirus crassus was abundant within all survey zones (Section 6: Colour plate 2) and observed on gorgonians and boulders. Mussels (Perna viridis) were observed on artificial substrate close to the outfall/intake pipes within the Reclamation Site Zone. Several species of sea urchin including Diadema setosum were recorded particularly along the Ash Lagoon Seawall Zone. One adult and one juvenile spiny lobster (Panulirus sp.) were recorded along the Ash Lagoon Seawall Zone. Several unidentified species of ovulids (snails) were recorded in association with the gorgonians. Hydroids (Aglaophenia sp.) were abundant on boulders within the Ash Lagoon Seawall Zone and crinoids (feather stars) were recorded within all survey zones.

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4. Discussion

The ahermatypic and octocorallian communities of Hong Kong’s inshore waters have been reported from the relatively deeper waters of the southeast islands and mainland coastline including Cape d'Aguilar Marine Reserve (Scott 1984; Zou and Scott 1982; Clark 1997). The limited documentation of octocorals all conclude that the greatest diversity and abundance are recorded from the southeast waters of Hong Kong. Octocorals from the orders Gorgonacea and Alcyonacea were, however, the dominant epifauna of the subtidal assemblages recorded on the western side of Lamma Island at identified Thermal Plume sites (T2-T6) (ERM 1999). More recent records by two internationally renowned soft coral scientists Dr Katharine Fabricius (Australian Institute of Marine Science) and Professor Hudi Benayahu (University of Tel Aviv) for twenty hard substrate sites (November 1999, unpublished report for the Swire Institute of Marine Science) revealed azooxanthellate octocorals were predominately recorded on hard substrate in deeper areas with moderately high sediment deposits. They did, however, record a rich soft coral assemblage mainly based on shallow (<6 m depth), artificial substrate at Junk Bay.

Soft coral assemblages dominated by azooxanthellate gorgonians were the primary epifaunal component of the three subtidal survey zones at the Lamma Power Station. All three zones contained one abundant Euplexaura sp. (white whip coral). The Ash Lagoon Seawall and Ash Lagoon Base Zones possessed all gorgonian species recorded within the Reclamation Site Zone, however, two species of soft coral, i.e., Scleronephthya sp. and Alcyonium sp. were only recorded from the Reclamation Site Zone.

Comparison of results obtained by the ROV survey carried out within the Reclamation Site Zone in 1998 (ERM 1999) revealed recordings of similar arborescent, octocoral genera although there are some differences in identification when compared with results presented here. It should be noted that the study of soft corals (globally) has been hindered by the requirements necessary for species identification which include electron microscopy work and there are only five taxonomic experts operating at this level worldwide. In this report octocorals were identified to genus level. The high abundance of Euplexaura recorded from the ROV surveys is consistent with the SCUBA surveys undertaken in the present survey work. It was noted that four Echinogorgia and one Muricella gorgonian species were recorded during the present study. SCUBA surveys allowed for the assessment of a wider area of seabed within each zone and more representative colony counts within each zone despite the extremely low visibility experienced.

Studies of soft coral abundance on the Central Great Barrier Reef (Fabricius 1997) revealed the importance of physical parameters such as exposure and water flow and these parameters exert a strong control on soft coral distribution. Soft corals are passive suspension feeders and are dependent on water flow for particle transport. A strong tidal current occurs in the area of the three survey zones and it is thought the availability of suitable hard substrate and water flow facilitate the colonisation and maintenance of the rich soft coral assemblages recorded from a depth of ~ 8-11 m with the Reclamation Site Zone, Ash Lagoon Seawall Zone and Ash Lagoon Base Zone. ERM (1999) noted the absence of trawling activity also aided the establishment of the soft coral epifauna, however, high gill netting activity was observed during fieldwork and discarded nets were implicated as a causative factor of the high levels of partial mortality recorded for Euplexaura sp. within the Ash Lagoon Seawall Zone.

At the present time there is an immense lack of knowledge on distribution and composition of soft coral assemblages within Hong Kong’s inshore waters. Scientific surveys have documented the existence of octocorals at deeper, hard substrate sites in the southeast region of Hong Kong and consultancy surveys are expanding the known locations of soft coral sites, however, a baseline from which to compare the present results with is not available. The results of the present study indicate that soft corals can exist at shallower depths when physical parameters are suitable. Although physical parameters suitable for soft coral growth are known, the specific levels of such parameters have not yet been defined for Hong Kong’s soft corals. Water flow for particle transport, suitable hard substrate and moderate sediment loading are important factors and these parameters would appear to be primary contributing factors to the existence of the soft coral assemblages of the Reclamation Site Zone, Ash Lagoon Seawall Zone and Ash Lagoon Base Zone of Lamma Power Station. The dominant Euplexaura sp. (white whip coral) appears to be an opportunistic, weed-like organism and with the provision of suitable hard substratum recolonisation after the construction works should be possible. There is no information on the reproductive strategies of local soft coral species, however, research in the Red Sea and the Great Barrier Reef has indicated that many gorogonians and species of the family Alcyoniidae, i.e., Dendronephthya sp., are broadcast spawners and may have annual or diffuse spawning periods (Babcock et al. 1986; Ben-David-Zaslow and Benayahu 1998). Soft coral larval sources for the three survey zones are not known, however, the role of the area as a seeding source for the recolonisation of soft corals after construction works may be important in combination with larval sources from further away.

5. References

Babcock, R.C., Bull, J.D., Harrison, P.L., Heyward, A.J., Oliver, J.K., Wallace, C.C. and Willis, B.L. 1986. Synchronous spawning of 105 scleractinian coral species on the Great Barrier Reef. Marine Biology 90:379-94.

Ben-David-Zaslow, R. and Benayahu, H. 1998. Competence and longevity in planular of several species of soft corals. Marine Ecology Progress Series 163:235-43.

Clark, T.H. 1997. The distribution of ahermatypic corals at Cape d’Aguilar, Hong Kong. In The Marine Flora and Fauna of Hong Kong and Southern China IV (ed. B. Morton). Proceedings of the Fourth International Marine Biological Workshop: The Marine Flora and Fauna of Hong Kong and Southern China, Hong Kong 1995. Hong Kong: Hong Kong University Press.

DeVantier, L.M., G. De’ath, T.J. Done and Turak, E. 1998. Ecological assessment of a complex natural system: a case study from the Great Barrier Reef. Ecological Applications 8:480-96.

EGS 2000. Marine archeological investigation Lamma Power Station Extension. Geophysical (side scan) survey final report. Survey Report for The Hong Kong Electric Co Ltd.

Environmental Resources Management Ltd. 1999. Environmental Impact Assessment of a 1800 MW Gas-Fired Power Station at Lamma Extension: Final Report - Volume 1. Survey Report for The Hong Kong Electric Co Ltd.

Fabricius, K.E. 1997. Soft coral abundance on the Central Great Barrier Reef: effects of Acanthaster planci, space availability and aspects of the physical environment. Coral Reefs 16:159-67.

Scott, P.J.B. 1984. The Corals of Hong Kong. Hong Kong: Hong Kong University Press.

Zou, R.L. and Scott, P.J.B. 1982. The Gorgonacea of Hong Kong. In The Marine Flora and Fauna of Hong Kong and Southern China I (ed. B. Morton and C.K. Tseng). Proceedings of the First International Marine Biological Workshop: The Marine Flora and Fauna of Hong Kong and Southern China, Hong Kong 1980. Hong Kong: Hong Kong University Press.

6. Colour plates

Plate 1. The three common Euplexaura spp. Left side of photograph shows the dominant Euplexaura sp. (white whip coral), centre right shows the common red/brown Euplexaura sp. (distinct white polyps are usually visible and to the far right, just in the photograph is the orange whip coral, another species of Euplexaura.

Plate 2. The common white whip Euplexaura sp. observed with the abundant sea cucumber Colochirus crassus attached.

Plate 3. The dominant gorgonian Euplexaura sp. (white whip coral) recorded from all three survey zones.

Plate 4. Close-up photograph of the distinct white polyps of a Euplexaura sp. (Brown/red body). This species was common although abundance was low with one-two colonies recorded amongst the dense stands of the white whip corals (Euplexaura sp.) observed on boulders.

Plate 5. Common fan gorgonian Echinogorgia lama recorded within all three survey zones.

Plate 6. Fan shaped gorgonian Echinogorgia sp. (red) recorded from the Ash Lagoon Seawall Zone only.

Plate 7. Dendronephthya sp. (white body, red spicules/polyps) colony. This species was recorded from all three zones

Plate 8. A bleached colony of Dendronephthya sp. photographed within the Reclamation Site Zone. It was noted that the majority of soft coral colonies recorded within the Ash Lagoon Seawall Zone were observed to be partially bleached and/or with an unhealthy appearance (colonies in a semi-collapsed state).

Plate 9. A colony of Scleronephthya sp. recorded from the Reclamation Site Zone only, seen here behind the common white whip coral (Euplexaura sp.).

Plate 10. The common ahermatypic coral Tubastrea sp. recorded on boulders within the Reclamation Site Zone and Ash Lagoon Seawall Zone.

Plate 11. Dense aggregation of Tubastrea sp. (ahermatypic coral) recorded from the Reclamation Site Zone.

Plate 12. The dominant white whip coral (Euplexaura sp.) showing the commonly observed partial mortality of the upper branches. Partial mortality was recorded for colonies of this species within all three zones.

Plate 13. Common unidentified white encrusting sponge recorded on boulders within the Reclamation Site Zone and Ash Lagoon Seawall.

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Appendix 1

Global Positioning System (GPS) locations for the transects within the three survey zones.

									Max
Transect	Deg		GPS N	GPS E		MAP N	MAP E		Depth
									(M)
T1	120		12.991	6.243		808384	829056		8.3
T2	100		12.893	6.268		808207	829100		8.7
T3	100		13.012	6.175		808421	828940		7.5
T4	90		13.041	6.210		808474	829001		8.1
T5	95		13.050	6.076		808490	828771		8.3
T6	95		12.854	6.134		808138	828869		8.5
T7	30		12.782	6.274		808008	829110		10.1
T8	100		12.811	6.047		808059	828721		10.3
T9	30		12.923	6.065		808262	828751		8.3
T10	60		12.925	6.154		808265	828904		9.5
TA1	140		12.990	6.399		808382	829324		7.3
TB1	100		12.953	6.441		808315	829396		7.5
TC1	80		12.949	6.520		808309	829532		6.5
TD1	60		12.963	6.564		808333	829608		7.1
TE1	30		12.983	6.610		808370	829686		6.8
TA2	130		12.971	6.382		808348	829295		10.6
TB2	100		12.931	6.444		808275	829401		10.3
TC2	60		12.931	6.521		808275	829533		10.1
TD2	70		12.948	6.582		808306	829638		9.8
TE2	50		12.973	6.619		808352	829702		9.3
Notes : GPS figures shown above are minutes & seconds only. I.e.,
12.973 = N22.12.973
6.619 = E114.06.619
All coordinates use the Hong Kong 1963 reference.
Angle of transect:
50 Deg = 50Deg Magnetic.

Appendix 2

Rapid Ecological Assessment (REA) results for all transects within the three zones surveyed.

Substratum and ecological attributes are based on estimated percentage covers for each transect:

All soft coral, gorgonian and ahermatypic coral species are presented as ordinal ranks based on taxon abundance:

Appendix 3

Survey data of gorgonian, soft corals and ahermatypic coral abundance for all transects within the three zone surveyed.

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