1 INTRODUCTION

1.1 BASELINE CONDITIONS

This Annex describes the baseline conditions of marine ecological resources within the Study Area (Section 1 - Figure 1.1a). Baseline conditions for each ecological component of the marine environment are evaluated based on information from the literature and specific field studies conducted for the purposes of this EIA.

1.1.1 Literature Review

The availability of literature on the marine ecology of the Study Area is variable. As with the majority of Hong Kong it appears that certain ecological components have been comprehensively studied whereas others have not. The list of relevant reports in the Study Brief has been reviewed along with relevant information pertaining to the ecological characteristics of Tolo Harbour, Tolo Habour and Mirs Bay. In order to assess the ecological value of these areas, a brief review of the relevant literature on the waters outside of the Study Area has also been conducted. The findings of this desk-top assessment are presented below in Section 2.

1.1.2 Focussed Field Surveys

Due to the limited recent literature available for some components of the marine ecosystem within the Study Area, field surveys were considered necessary to fill the information gaps identified and enable a complete and robust assessment of impacts to marine ecology to be performed. The findings of the field surveys are presented below as well as an outline of information on marine ecological resources, both within the Study Area and within close proximity, based on information gathered through desk-top reviews of available literature. The field surveys covered dry and wet seasons, where appropriate, and were agreed in advance with AFCD and EPD.

2 LITERATURE REVIEW

2.1 SOFT BENTHOS ASSEMBLAGES

2.1.1 Infaunal Assemblages

Information on the infaunal benthic assemblages in Tolo Harbour was obtained from a territory wide study of benthic community structure conducted using grab samples during 1976 to 1977 (1). The study concluded that the eastern waters of Hong Kong support infaunal benthic assemblages that are polychaete (72.5%) and crustacean (9.5%) dominated. The sediment was mainly composed of silt (88.7%). Species diversity at locations in east Hong Kong was ranked high (19.2 per 0.5 m2) when compared with other areas in Hong Kong (values ranging from 16.2 to 19.2 per 0.5 m2). The mean number of individuals was 88.2 m2 which is lower than the average for Hong Kong (101.4 m2) and the mean biomass for the area was 22.5 g m-2, which is low compared to the overall mean biomass for Hong Kong at 35.2 g m-2.

A survey in Eastern Waters, including Mirs Bay, Double Haven, Crooked Harbour, Tolo Channel, Tolo Harbour and Sai Kung, found polychaetes to represent high abundance (74%) but low biomass (5%), in contrast to low abundance (5%) and high biomass (74%) for molluscs (2). Overall mean biomass levels of 33 g m-2 recorded from the Eastern waters were typical of waters in the HKSAR (Shin and Thompson recorded an average of 35 g m-2 from Hong Kong waters in 1982). However, the infaunal benthos in Tolo Channel and Tolo Harbour were regarded as having been under environmental stress (pollution) for many years (3).

2.1.2 Epifaunal Assemblages

Trawl surveys were conducted since 1978 to collect epifaunal benthic community data at Tolo Harbour, Tolo Channel and Mirs Bay (1) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15). The studies were mainly conducted during the International Marine Biological Workshop organized by the University of Hong Kong.

The epibenthic assemblages of Tolo Harbour investigated using trawls were dominated with bivalves, coelenterates, gastropods, crabs and echinoderms (16). The trawl survey of benthos of Tolo Harbour and Channel in 1978 showed the species diversity of benthos were similar in Tolo Harbour (48 species) and Tolo Channel (46 species), but Tolo Harbour (418.1 mean no. of individual, ranging from 27 to 1523) had a higher number of individuals compared with Tolo Channel (120.7 mean no. of individual, ranging from 65 to 200) (17). 62 species of macrobenthos were recently recorded in eleven locations of Tolo Harbour, Tolo Channel and Mirs Bay, in which annelids (54.8%) and crustaceans (22.6%) were the dominant component (18). The number of species and individuals were higher in the locations within Mirs Bay (15 - 31 species per 0.15 m2, 31 - 89 individuals per 0.15 m2), but lower in Tolo Harbour (5 - 10 species per 0.15 m2, 6 - 27 individuals per 0.15 m2). A decreasing trend in terms of total organic matter and redox potential values in the sediment from inner to outer Tolo Harbour indicated a clear sign of ecological stress caused by organic enrichment. Indicators of organic pollution including polychaetes Minuspio cirrifera, Paraprionospio pinnata and Spiochaetopterus costarum, and the bivalve Fulvia hungerfordi have been reported in high numbers from Inner Tolo Harbour.

Reviewing the results of trawl surveys of sublittoral gastropods in Tolo Channel and Mirs Bay from 1976 to 1989, the numbers of species recorded in Mirs Bay (with a mean of 17.7, ranging 7 to 23) were generally higher than Tolo Channel (with a mean of 10.5, ranging 8 to 14) (19) (20). The dominant species in both areas were mainly Turricula nelliae.

Trawl surveys in Mirs Bay, Tolo Channel and Tolo Harbour were conducted in 1989. A total 19, 34 and 24 species of Brachyura and Anomura were recorded in Mirs Bay, Tolo Channel and Tolo Harbour respectively (21). Higher mean number of individuals of Brachyura and Anomura were recorded in Tolo Channel (132.18 individuals) compare with Mirs Bay (80.83 individuals) and Tolo Harbour (54.83 individuals). There were 10 and 11 species of penaeid prawns recorded in Tolo Harbour and Tolo Channel (dominated by Metapenaeopsis palmensis, 88.31 % frequency), and Mirs Bay (dominated by Metapenaeopsis palmensis, 67 % frequency; Metapenaeopsis barbata, 14.79 % frequency; Parapenaeopsis tenella, 10.73 % frequency) in 1989, respectively (22).

A total of 38 species and 2,522 individuals of fishes were recorded and identified from Tolo Harbour and Middle Tolo Channel (a total 36 trawls) (23). The results showed that two species, Callionymus kaianus (46.11%) and Chaeturichthys hexanema (36.92%), constituted >80% of the total number of individuals collected. Accordingly the results of the recent epibenthic ichthyofauna beam trawl survey, areas around Tung Ping Chau has the highest fish species richness (18 - 29 species) and moderate fish density (9 - 43 individuals per 0.1 ha) compared with the results from Middle Mirs Bay, Tolo Channel and Tolo Harbour (24). The fish species richness and fish density were lower in the locations within Tolo Channel (5 - 7 species) and Middle Mirs Bay (5 - 12 individuals per 0.1 ha) respectively.

2.2 HARD SURFACE ASSEMBLAGES

Approximately 80% of Hong Kong's complex shorelines and many islands are composed of rocky outcrops. Like all intertidal areas, shores in Hong Kong display characteristic zonation patterns, with a progression of different species along the vertical gradient from terrestrial to marine environments. For the purposes of this review, information will be presented on assemblages that occur along the full gradient from the essentially marine, subtidal area, to the semi-terrestrial, intertidal area.

2.2.1 Subtidal

Over 80 species of coral occur in Hong Kong, with the highest diversities recorded in eastern waters. It appears that coral distribution in Hong Kong is primarily controlled by hydrodynamic conditions as Hong Kong's western waters are influenced by the Pearl River, which lowers salinities. However, recent studies have found that coral distribution in Hong Kong may not be as restricted as was initially reported (25).

Coral reefs support a range of species providing sheltering, 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. For example, during the summer of 1994 the intrusion of hypoxic water into Mirs Bay, including along the proposed pipelines route, resulted in widespread mortality of both hard and soft corals (26).

Corals in eastern and southeastern waters of Hong Kong generally show a degree of vertical zonation.

Hard Corals

Coral species that require light for photosynthesis (ie hard/hermatypic corals) are generally restricted to the top six metres of the water column. Although some individuals may be recorded at depths of up to ten metres these are usually isolated colonies (27).

Soft and Black Corals

Soft corals and gorgonians (octocorals) on the other hand are generally found at greater depths than hard corals and are known to require conditions of high current flow for the transport of the suspended organic matter that they feed on. In general gorgonians can be said to be tolerant of turbid conditions although tolerance will vary depending on the species. Such tolerance appears to be attributed to the moving capability of soft corals that can help shaking off sediments and the physiological nature of soft corals, in which they do not contain photosynthetic algae, which depend on clear waters to allow penetration of sunlight. Such tolerance has been recently recorded as a recent survey examining octocorals in Hong Kong, found that of the twenty sites surveyed in Junk Bay at Tseung Kwan O, which is an area known to be highly turbid, had the greatest octocoral richness in terms of number of species (28) . In addition a survey at the site of the extension of the Lamma Power Station has recorded up to 1,000 colonies km-1 of the gorgonian Euplexaura sp also in turbid waters (29).

For black corals, they are considered to be more tolerant to increased sedimentation than hard corals due to their perceived higher tolerance to turbidity and their optimal conditions for growth and survival include greatly reduced light levels (30). Soft and black corals are therefore expected to be comparatively less sensitive to and have a higher tolerant level to suspended solids and sediment deposition than hard corals.

A number of areas in Tolo Channel and Mirs Bay have been reported as supporting high abundances and diversity of corals.

Coral Communities in the Vicinity of the Proposed Pipelines Route

Numerous studies have been conducted on the coral communities of Tolo Harbour and Eastern Waters, in particular those in Mirs Bay. The majority of these studies have specifically focussed on hard coral communities, and as a result, this review will specifically focus on such communities. However, it should be noted that as part of the Environmental Impact Assessment, both hard and soft (octocorals) coral communities will be investigated.

In addition to the above, it would appear that a number of the studies investigating coral communities in the vicinity of the proposed pipelines are now out of date due to the increasing population growth and infrastructure development in and around Tolo Harbour. As a result, the review of relevant information has primarily focussed on studies that are considered applicable to present day conditions. Reference has been made to historical studies where necessary, however, the results presented in the earlier studies should be treated with caution due to the long time span since the data were collected.

In order to provide a complete and comprehensive review of the existing hard coral communities in the vicinity of the proposed pipeline route, the region has been divided into four key areas (Figure 2.1a). These are as follows:

* Tolo Harbour;

* Tolo Channel;

* Tolo Approach (including Hoi Ha Wan); and,

* Mirs Bay (including Tung Ping Chau).

A review of studies of hard coral communities that have included study sites in one of these four areas, or combination of any of the four, is presented below.

Tolo Harbour

Two of the earliest studies of hard coral communities in Hong Kong included a number of sites in Tolo Harbour (Figure 2.1b) (31) (32). Whilst the data presented in these studies is of some use as an indicator of past conditions of hard coral communities in Tolo Harbour, the data are now out-of-date as the surveys were conducted in 1980 and 1986, respectively. The fact that this information can now be considered to be out-of-date has been demonstrated in a recent study conducted in 1998 reporting on coral abundance, diversity and metal burdens (33). This study provides a comparison of the results of all three studies as well as the most up-to-date information on hard coral communities in the Tolo Harbour.

The temporal comparison of the findings of the 1980, 1986 and 1998 surveys provides an indication of potential hard coral community changes over time in the Tolo Harbour area. Two sites were surveyed in each of the three studies; Tai Po Tau and A Chau (Figure 2.1b). The results of the 1998 survey indicated that there had been no recovery from the findings reported in the previous studies at the Tai Po Tau site, where it was reported that 100% of the hard corals recorded in 1980 (2 species, sparse cover) had been lost by 1986 (34). At the A Chau site it was reported that in 1986 that there had been a 36% decrease in hard coral abundance (9 species) and a 100% decrease in cover from what was recorded in 1980 (14 species, 5% cover) (35). However, the results of the more recent survey, conducted in 1998 and considered to be the most applicable as an indication for potential existing hard coral communities in the Tolo Harbour area, reported that in the 1998 surveys no hard coral communities were recorded at either the Tai Po Tau site or the A Chau site. As a result, it would appear that Tolo Harbour does not support hard coral communities.

Tolo Channel

In addition to the two study sites in the Tolo Harbour area surveyed in the 1980 (36), 1986 (37) and 1998 (38) study described above, two study sites were also surveyed during each of these studies in the Tolo Channel area. Again, the comparison of results from these studies provides an indication for potential existing hard coral communities in the Tolo Channel area.

The two survey sites available for comparison are located at Bush Reef and Knob Reef (Figure 2.1b). Both sites are small outcrops in the middle of Tolo Channel, with Knob Reef having a more easterly location. The results of the 1980 study found that Bush Reef supported 25 species of hard corals with 70% coral coverage, whereas, Knob Reef was also found to have 25 hard coral species but with 80% coral coverage. When re-surveyed in 1986, the number of corals at Bush Reef had reduced by 20% to a total of 20 species, whereas, the coverage had dropped by 86% to only 10% coral coverage. Similarly, the 1986 survey at Bush Reef found that between 1980 and 1986 there was a 40% decrease in numbers of hard coral species with only 15 recorded in 1986 when compared to 1980, and a 94% reduction in hard coral coverage with only 5% coral coverage in 1986 compared to 80% cover in 1980 (39).

The results of the 1998 study, however, found further reductions in numbers of hard corals and coral coverage. This study found only 1 coral species at Bush Reef, indicating a 95% reduction from the 1986 study, whereas, a 100% loss in coral coverage was recorded with no coral coverage reported (40). A similar finding was recorded at Knob Reef with a 67% reduction in diversity of hard coral species with only 5 species recorded in 1998 and a 60% decrease in coral coverage with only 2% cover recorded in 1998 compared to 5% cover in 1986.

In addition to the above studies, four other sites were surveyed to investigate hard coral communities within the Tolo Channel area during the Civil Engineering Department commissioned Coastal Ecology Studies (41) (42). These sites are located at Fu Tau Sha, Wong Wan Tsui and at two headlands off Tam Chai Shan (Figure 2.1b). Whilst the results of these studies report that the study sites are of medium to high conservation value, the results are considered to be of limited use as the surveys were qualitative and do not provide an indication of coral abundance, diversity or coverage.

It would appear, therefore, that based on the above reported results that the Tolo Channel does support existing hard coral communities.

Tolo Approach

Of the four areas discussed in this review, the Tolo Approach area has been most intensively investigated for hard coral communities. This area contains both the Hoi Ha Wan Marine Park and the islands of Chek Chau and Tap Mun, as well as those fringing the Yan Chau Tong/Lai Chi Wo Marine Park. However, although the area has been intensively studied, there appears to be a lack of data on the coral communities on the northern coastline of the Tolo Approach.

As with the Tolo Harbour and Channel areas, the most recent and representative study on hard coral communities in the Tolo Approach area was the survey conducted in 1998 to update data gathered at the same survey sites in the 1980's (43). During the 1998 survey, three sites were surveyed; one located at Fung Wong Fat on the northern coastline of the Tolo Approach, one at Gruff Head at the entrance to the Hoi Ha Wan Marine Park and one at Chek Chau, an island directly outside the approach to the Tolo Channel (Figure 2.1b). Only the latter of these sites was surveyed during the 1980 and 1986 surveys. The results of these surveys at these sites are discussed in turn below.

As mentioned above, no surveys on hard coral communities were conducted at Fung Wong Fat during 1980 and 1986, however, surveys took place in 1998 (44). The results of this survey described the habitat as a shallow inlet with a degraded fringing coral community. In terms of hard coral colonies, 17 species were recorded with 10% coral cover.

Gruff Head was found in the 1998 survey to support both higher numbers of species of coral, as well as a higher percentage of cover in comparison to the communities recorded at Fung Wong Fat (45). In comparison to the results of the surveys conducted in 1980 and 1986, a reduction in both these parameters was recorded. In 1980 a total of 30 species of hard coral were recorded, which although found to be the same in the 1986 survey, was found to have decreased by 27% in the 1998 survey with only 22 species of hard coral recorded. In terms of percentage cover, it was recorded in 1980 that there was 70% coral cover, which although reported as unchanged in the results of the 1986 survey was found to have decreased by 46% in the 1998 survey with reports of only 38% coral cover (46).

Chek Chau, in comparison with the other two sites, was found to support the highest number of species of hard coral as well as the highest percentage cover of hard coral communities. Although a reduction of 9% in the number of species was recorded between 1980 (33 species recorded) and 1986 (30 species recorded), and a further reduction of 17% between 1986 and 1998, a total of 25 species of hard coral were still recorded at this site. Percentage of coral cover also remained high, with 60% cover recorded in 1998, however, in both 1980 and 1986 90% coral cover was recorded, equivalent to a 34% decrease.

In addition to the above studies on hard coral colonies, a number of other sites within the Tolo Approach have been investigated during the Hong Kong-wide Coastal Ecology Studies (Figure 2.1b) (47) (48). Whilst the results of these studies report that the sites were of medium to high conservation value, the results are of limited use as the surveys were qualitative and do not provide an indication of coral abundance, diversity or coverage.

Further data that are of more use as an indication for potential existing hard coral communities in the Tolo Approach area are available through studies prior to the establishment of the Hoi Ha Wan and following the establishment of the Yan Chau Tong/Lai Chi Wo Marine Parks (Figure 2.1b) (49) (50).

In a similar fashion to the 1998 study discussed above, a study conducted in 1989 compares the results to a previous survey conducted in 1980 (51). The study showed that from the ten survey sites in Hoi Ha Wan, there was an average decrease of 32% in hard coral cover. In terms of number of hard coral species recorded, there was an average decrease across the ten sites of 19%. The maximum site decrease was from 18 to 9 species, whereas, at two sites minor increases in numbers of coral species were recorded.

The second of these surveys is more up-to-date as it reports on surveys conducted in 1998, however, the location of the majority of the survey sites can be considered to be outside of the boundaries of this assessment. As a result, only one of the survey sites on Double Island, an island fringing the Yan Chau Tong/Lai Chi Wo Marine Park is considered applicable. Unfortunately, as with the results of the Coastal Ecology Studies, the survey conducted at this site was qualitative. The site was, however, reported to have a thin, shallow fringing coral community with 8 species recorded. As the survey was qualitative, no information was presented on the percentage cover of the hard coral communities. Based on the above reported results, it would appear that there are various sites within the Tolo Approach area that support existing hard coral communities. A number of these sites, such as Chek Chau, appear to support a high number of species and coral coverage in comparison to other sites in the area and in vicinity of the proposed pipelines route.

Mirs Bay

In the Mirs Bay area, hard coral communities are restricted to the island of Tung Ping Chau. The waters surrounding this island were awarded Marine Park status in 2001 to promote nature conservation, education and research. Prior to designation, two detailed studies were conducted on the marine ecology of Tung Ping Chau and provide the most up-to-date information on the hard coral communities on the island (52) (53). These studies report on surveys conducted between 1995 and 1998 and from 1997 to 1998, respectively.

The first of these studies reported that due to wave exposure on the west, coral communities are generally restricted to the eastern shoreline of Tung Ping Chau. As a result, three sites were quantitatively surveyed on the eastern shore of the island; the southeastern region, the central region to the north of the existing ferry pier and the northeastern region (Figure 2.1b). The results of this survey reported that all sites were similar in terms of number of hard coral species and percentage cover of hard corals with the southeastern region recording 22 species and a hard coral cover of 61%, the central region also recording 22 species and a hard coral cover of 56% and the northeastern region recording 21 species and a hard coral cover also of 56% (54). It is worth noting that a cover of dead coral was also reported for each site, ranging from 15% at the central region to 20% at the southeastern site.

The second of these studies provides quantitative data on hard coral communities from two sites on the eastern side of Tung Ping Chau, as well as qualitative information on the habitat from three sites on the western side of the island. The two sites on the east, namely A Ye Wan and A Ma Wan are located in a similar position to the southeastern and northeastern survey sites discussed above. The A Ye Wan site recorded a maximum of 19 hard coral species and a maximum hard coral cover of 58%, whereas, A Ma Wan recorded a maximum of 23 hard coral species and a maximum hard coral cover of 70%. In terms of the survey sites on the west of the island, coral cover was reported to be generally less than 10% with low numbers of corals which were generally of a small size (55).

In addition to the studies on hard coral communities in the Mirs Bay area, it should be noted that the recent study on octocorals in Hong Kong waters had also surveyed the island of Tung Ping Chau in the Mirs Bay area as part of the study (56). The findings of these surveys found that three phototrophic soft corals (ie species with zooxanthellae) were present at Tung Ping Chau, which was high compared to other sites in Hong Kong.

It is also worth noting that extensive epifaunal surveys have been conducted to west of Tung Ping Chau when examining a similar proposed pipeline route for The Hongkong Electric Co Ltd (HEC) (57). For these surveys, a Remote Operated Vehicle (ROV) was used to provide video footage of the seabed. Over a period of three weeks a total of 13 transects were surveyed, each 600m in length, equalling a total of 7,800km surveyed. Analysis of the footage showed that the seabed was predominantly flat and muddy, with few features other than burrow holes. On three transects occasional solitary seawhips (gorgonians) were observed, however, these were sporadic and of low numbers. With the exception of these seawhips and two sea cucumbers, no epifaunal organisms or corals were recorded during the survey.

The results of these three studies indicate that both hard and soft coral communities of note are present in the Mirs Bay area, although are restricted to the island of Tung Ping Chau. These communities appear to have a relatively high number of species and high coral cover in comparison to other sites in vicinity of the proposed pipeline route.

2.2.2 Intertidal

Many of the natural intertidal assemblages in Tolo Harbour have been lost and replaced with artificial seawalls through recent reclamation works. Artificial seawalls are colonised by typical fouling organisms and are generally of lower ecological value than natural rocky shores (58). There are many areas of natural rocky shores, with some natural sandy shore scattered, along Tolo Channel and in Mirs Bay. Similar to other rocky shores in Hong Kong, the vertical distribution of rocky intertidal communities along Tolo Harbour and Tolo Channel were reported of three zones including littorine zone characterised by Nodilittorina pyramidalis and N. millegrana, barnacle-oyster zone characterised by Balanus amphitrite amphitrite, Tetraclita squamosa squamosa, Saccostrea echinata and Ostrea glomerata, and mussel-sacidian or algal zone (59). Due to the relatively remote locations of these shores and their distance from sources of pollution they are likely to be of medium to high ecological value.

There are two large mangrove stands (Ting Kok and Kei Ling Ha) and several mangrove patches (ie Yung Shue Au and Lai Chi Chong), as well as some mud/sand flats, located in the Tolo Harbour and Tolo Channel. Due to the remoteness of the mangrove stands and mud/sand flats from the proposed gas pipelines route, no impacts on such habitats will be expected, and therefore they are not discussed in detail.

2.3 MARINE MAMMALS

The review below is based on stranding records collected in Hong Kong since 1973 (60), and detailed studies conducted on the ecology of Hong Kong's small cetaceans since 1994 (61) (62) (63) (64) (65) (66) (67) (68)(69) (70). Ten stranding records of fourteen species of cetacean, including Balaenoptera acutorostrata, Grampus griseus, Sousa chinensis, Stenella coeruleoalba, Tursiops truncates and Neophocaena phocaenoides, were reported previously. The Indo-Pacific Humpback Dolphin, Sousa chinensis, and the Finless Porpoise, Neophocaena phocaenoides, are the only species of marine mammal regularly sighted in western or southern and eastern Hong Kong waters, but not within Tolo Harbour nor Tolo Channel.

Findings of a recent survey undertaken by Jefferson et al (2002) on the distribution and abundance estimates of Finless Porpoises in Hong Kong showed that the species occurred in Hong Kong waters year-round, but showed evidence of seasonal movements, with porpoises largely vacating most of Hong Kong's southwestern waters in summer and autumn. Finless porpoises were found to occur in the southern and eastern waters of Hong Kong, including South Lantau, East Lantau, Lamma, Po Toi, Ninepins, Sai Kung and Mirs Bay. The southern waters (including South Lantau, Lamma, and Po Toi areas) were considered as important habitat for finless porpoises in Hong Kong, although there were seasonal differences in their use (being more abundant during the spring season).

The eastern waters, including Ninepins, Sai Kung and Mirs Bay, appeared to be used by the species throughout the year, but the area within Tolo Harbour and Tolo Channel did not appear to be used by porpoises (71). The sighting frequencies (0.7 in spring to 2.4 in winter) recorded in Mirs Bay were very low when compared to the values recorded for South Lamma (2.3 in summer to 52 in spring) and Po Toi (1.8 in spring to 16.5 in summer). Therefore, the marine waters in the vicinity of the pipelines alignment, including Mirs Bay, are not considered as important habitats for Finless Porpoises and thus will not be identified as ecological sensitive receivers for this Project.Marine Ecological Sensitive Areas

2.3.1 Marine Parks

There are three Marine Parks in the Study Area at Yan Chau Tong, Hoi Ha Wan and Tung Ping Chau (Figure 2.4a). Marine Parks are gazetted for conservation, recreation and educational purposes and are under the control of the Country and Marine Parks Authority (CMPA).

2.3.2 Sites of Special Scientific Interest (SSSIs)

There are several SSSIs located within the Study Area which have been designated for a variety of reasons, eg the SSSIs at Ting Kok and Kei Ling Ha were established because of their large mangrove stands, whereas Sham Chung was established because of the large number of fossils present there.

2.3.3 Proposed and Gazetted Artificial Reefs

Artificial reefs (ARs) have been deployed in the Yan Chau Tong and Hoi Ha Wan Marine Parks and are proposed for deployment within Long Harbour. ARs are deployed to enhance fisheries and marine ecological resources and are under the jurisdiction of AFCD.

3 FIELD SURVEYS

3.1 INTRODUCTION

To fill gaps in the literature, surveys were conducted such that the ecological characteristics of the habitats and faunal and floral assemblages present could be identified and impacts due to the pipelines evaluated.

3.2 ARTIFICIAL BOULDER SHORE (TAI PO)

3.2.1 Methodology

Rocky shore as well as artificial boulder shore organisms originated in purely marine habitats and have evolved and adapted to live on intertidal shores. The extent of their adaptations to this habitat will dictate where they are found on the shore. The more adapted a species is to terrestrial conditions the higher it will be found on the shore, causing zonation patterns. The survey design involved sampling the main intertidal zones so that the vertical range of all species was represented. The artificial boulder shore at the proposed pipeline landfall at Tai Po was surveyed using a quantitative belt transect method. A total of three sites were chosen for field surveys along the waterfront at Tai Po (Figure 3.2a). Horizontal (belt) transects were set up along the shore line and surveyed at two heights up the shore at 50 cm intervals perpendicular to the waterline starting at 1 m above Chart Datum. On each transect, 10 quadrats (50 x 50 cm) were placed randomly to assess the abundance and distribution of flora and fauna. Previous studies of Hong Kong's rocky shores have shown that 10 quadrats (50 x 50 cm) randomly placed along each transect will produce accurate, unbiased samples of the community (72). The survey quadrats were placed along the transects at points determined through the use of random number tables to ensure no bias to the sampling. All animals found in each quadrat were identified and recorded to species level so that density m-2 could be determined. Sessile animals such as barnacles and oysters in each quadrat were not counted but estimated as a percentage of coverage on the rock surface. All species of algae (encrusting, foliose and filamentous) were also identified and recorded by estimating the percentage of cover of the rock surface. As seasonal changes in the intertidal region are very marked, surveys were conducted two times, once in the dry (28 March 2002) and once in the wet (23 July 2002) season to ensure no rare/highly seasonal species were missed.

The assemblages recorded on the shores were identified with the aid of Morton and Harper (1995) (73), Morton and Morton (1983) (74), Hu and Tao (1995) (75) and Lai (1998) (76).

3.2.2 Results

Dry Season

Animals recorded on the artificial seawall were mainly periwinkles (Nodilittorina pyramidalis and Nodilittorina radiata) on the high shore (Table 3.2a). Raw data are presented in Appendix A. The predatory gastropod Thais clavigera (the common dogwhelk) was also recorded in the low shore region. Sessile filter-feeding organisms such as the rock oyster (Saccostrea cucullata) and barnacles (Tetraclita squamosa) were also common on the shores (Table 3.2a). The limpet (Patelloidea pygmaea), the mussels (Perna viridis) and the bivalve (Isognomon legumen) were also recorded on the shores but in low abundances. Highly mobile organisms, including Metapograpsus messor and Ligia exotica, were also observed during the survey.

Table 3.2a Mean Number of Individuals (m-2) (+/- Standard Deviation) of Intertidal Organisms Recorded from the Artificial Seawall During the Dry Season Survey

	Site A		Site B		Site C
	High-intertidal Zone	Low-intertidal Zone	High-intertidal Zone	Low-intertidal Zone	High-intertidal Zone	Low-intertidal Zone
Snail
Nodilittorina pyramidalis	0.8±2.53	0	2±4.32	0	1.2±2.7	0
Nodilittorina radiata	9.2±13.07	0	12.4±13.91	0	10.8±14.61	0
Patelloidea pygmaea	0	0	0	0	0.8±2.53
Thais clavigera	0	0	0	0.4±1.26	0	1.2±1.93
Barnacle (% cover)
Tetraclita squamosa	0	10.1±11.45	0.1±0.32	14±10.22	0.2±0.42	12±9.19
Bivalve (% cover)
Perna viridis	0	0	0	0.5±1.58	0	0.1±0.32
Saccostrea cucullata	0	23.5±25.61	0	37.5±17.04	0	33±24.18
Isognomon legumen	0	0	0	0.5±1.58	0	1±2.11
Algae (% cover)
Encrusting algae	0	13±27.51	0	0	0	5±12.47

Wet Season

Animals recorded on the artificial seawall were mainly periwinkles (Littoraria articulata and Nodilittorina radiata) on the high shore (Table 3.2b). Raw data are presented in Appendix A. The predatory gastropod Thais clavigera (the common dogwhelk) was also recorded in the low shore region. Sessile filter-feeding organisms such as the rock oyster (Saccostrea cucullata) and barnacles (Tetraclita squamosa) were also common on the shores (Table 3.2b). The limpet (Patelloidea pygmaea), the mussels (Perna viridis) and the bivalve (Isognomon legumen) were also recorded on the shores but in low abundances. Highly mobile organisms, including Thalamita danae, Metapograpsus messor and Ligia exotica, were also observed during the survey.

Table 3.2b Mean Number of Individuals (m-2) (+/- Standard Deviation) of Intertidal Organisms Recorded from the Artificial Seawall During the Wet Season Survey.

	Site A		Site B		Site C
	High-intertidal Zone	Low-intertidal Zone	High-intertidal Zone	Low-intertidal Zone	High-intertidal Zone	Low-intertidal Zone
Snail
Littoraria articulata	0	0	0.4±1.26	0	0.8±2.53	0
Nodilittorina radiata	12.8±18.46	0	7.6±12.14	0	12.0±16.55	0
Patelloidea pygmaea	0	0.4±1.26	0	0.4±1.26	0	1.2±1.13
Thais clavigera	0	0.4±1.26	0	2.0±6.32	0	0
Barnacle (% cover)
Tetraclita squamosa	1.0±1.7	13.5±7.09	0.1±0.32	11.5±7.47	0.1±0.32	15.0±10.54
Bivalve (% cover)
Perna viridis	0	0	0.2±0.63	0	0	0.1±0.32
Saccostrea cucullata	0	22.5±13.59	0	31.5±13.13	0	29.5±16.57
Isognomon legumen	0	0.1±0.32	0	0.3±0.67	0	0.2±0.63
Algae (% cover)
Encrusting algae	0	1.0±2.11	0	0.5±1.58	0	0

The intertidal assemblages recorded on the artificial seawall in the dry season were similar to those recorded in the wet season. The number of faunal species identified were the same (ie 8) for both seasons with comparable faunal abundances. The percentage coverage of encrusting algae recorded in the dry season was higher than the percentage obtained in the wet season. No species of ecological importance was recorded on this sloping seawall and the assemblages recorded are similar to those recorded on natural sheltered intertidal hard surface shores.

3.3 SUBTIDAL BENTHIC GRAB SURVEY

3.3.1 Methodology

Field Techniques

The benthic grab samples were collected from seven representative areas along the submarine pipeline alignment in Hong Kong waters. The seven representative areas will be as follows (Figure 3.3a):

1. Tai Po landfall;

2. Jetting area at Ma Shi Chau;

3. Jetting area in Tolo Channel;

4. Jetting area in Wong Chuk Kok Tsui;

5. Tee-off location;

6. Jetting area in Yantian Approach; and,

7. Jetting area in Mirs Bay near Tung Ping Chau.

In each of the seven areas 6- 8 stations that were no closer than 50m apart were established and one grab sample 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. The grab was lowered slowly through the water column (at an approximate rate of 30 cm s-1) to prevent it from flipping during descent or creating a pressure wave sufficient to grossly disturb bottom sediments. After the grab was triggered, it was raised at a constant rate, carefully retrieved, and placed in a level position on a stand. The samples were evaluated for acceptance based upon the degree of disturbance, penetration depth, and amount of leakage from the grab. Samples with minimal disturbance of surface sediments and adequate penetration depth were accepted, however, samples were rejected if the grab had overfilled or there is leakage of sample material from the grab.

The sediments were sieved on board by ERM marine scientists. 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. All the samples were collected from March, May and July 2002.

Laboratory Techniques

Upon arrival at the benthic laboratory, all benthic samples were re-inventoried and checked against chain-of-custody forms. If a sample consisted of multiple containers, all containers were processed as a group.

Sample re-screening was performed by the benthic laboratory 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 (m and 1 mm mesh sieves were gently rinsed with fresh water into a 250 (m 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. All sorted samples were systematically checked to ensure all QA/QC procedures were adhered to before proceeding to the taxonomic identification, enumeration, and biomass determination phases of the project.

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 minimises 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).

QA/QC Techniques

Sorting QA/QC was performed using 25-power magnification by someone other than the original sorter. Twenty percent of each sorted sample were re-sorted to ensure 95 percent sorting efficiency. A sample only passed QA/QC if the number of organisms found during the QA/QC check did not represent more than 5 percent of the total number of organisms found in the entire sample. If the number of organisms found was greater than 5 percent of the total number, the entire sample was resorted. Samples that contained uncertain identifications were sent out for independent re-identification by a qualified regional expert.

3.3.2 Results

Dry Season

There were a total of 45 species and 324 individuals of benthic organisms recorded at the seven sites (Tai Po Approach, Ma Shi Chau, Tolo Channel, Wong Chuk Kok Tsui, Tee-off, Yantian Approach and Mirs Bay), most of them belonging to the Phylum Annelida (these all being polychaete worms) (Table 3.3a). The total biomass (wet weight) recorded from the benthic samples was 103.84 g for all grab samples. Raw data are presented in Appendix A. There were eight major taxa (Phylum) recorded in the benthic samples. No rare species were recorded in the samples during the survey. The total number of individuals and density was highest at Mirs Bay (total number was 106 station-1, equivalent to 1104.17 m-2), while lowest at Tee-off (total number was 15 station-1, equivalent to 156.25 m-2). The total number of species recorded was highest at Mirs Bay (25 species station-1), while lowest in Tai Po Approach, Ma Shi Chau, Tee-off and Tolo Channel (with 8 species station-1 in each site). The total biomass recorded was highest at Mirs Bay (44.51 g wet wt station-1, equivalent to 463.69 g m-2), while lowest in Ma Shi Chau (0.14 g wet wt station-1, equivalent to 1.49 g m-2).

Table 3.3a Number of Individuals, Species and Biomass (Wet Weight) (+/- Standard Deviation) of Benthos Recorded per Station During the Dry Season Survey.

Site	Total no. of individuals	Total no. of species	Total biomass (g)	Mean no. of individuals	Mean no. of species	Mean biomass (g)
Samples from March 2002
Mirs Bay (MB) (6 stations)	106	25	44.51	17.67±3.14	9±2	7.42±2.93
Wong Chuk Kok Tsui (WCKT) (6 stations)	45	10	22.01	7.5±3.27	3.17±0.75	3.67±5.0
Tolo Channel (TC) (6 stations)	59	8	9.77	9.83±7.68	3.83±2.64	1.63±2.56
Ma Shi Chau (MSC) (6 stations)	35	8	0.14	5.83±9.06	2±2.1	0.02±0.03
Tai Po Approach (TPA) (8 stations)	26	8	3.76	3.25±8.8	1±2.45	0.47±1.31
Samples from May 2002
Yantian Approach (YA) (6 stations)	38	15	15.59	6.33±5.99	4±3.35	2.60±3.40
Tee-off (TO) (6 stations)	15	8	8.06	2.5±1.38	2.17±1.17	1.34±2.08
Total no. of individuals	324
Total no. of species		45
Total biomass (g)			103.84

Wet Season

There were a total of 27 species and 137 individuals of benthic organisms recorded at the seven sites (Tai Po Approach, Ma Shi Chau, Tolo Channel, Wong Chuk Kok Tsui, Tee-off, Yantian Approach and Mirs Bay) during the wet season survey (Table 3.3b). The majority of the number of organisms recorded were either from the Phyla Mollusca or Annelida or Echinodermata. The total biomass (wet weight) recorded from the benthic samples was 85.36 g for all grab samples. Raw data are presented in Appendix A. There were seven major taxa (Phylum) recorded in the benthic samples. No rare species were recorded in the samples during the survey. The total number of individuals and density was highest at Yantian Approach and Tolo Channel (total number were 35 station-1, equivalent to 364.58 m-2), while lowest at Wong Chuk Kok Tsui (total number was 4 station-1, equivalent to 41.67 m-2). The total number of species recorded was highest at Yantian Approach (16 species), while lowest in Tai Po Approach and Ma Shi Chau. The total biomass recorded was highest at Tee-off (29.7 g wet wt station-1, equivalent to 309.32 g m-2), while lowest in Ma Shi Chau (14.23 g wet wt station-1, equivalent to 463.69 g m-2).

Table 3.3b Number of Individuals, Species and Biomass (Wet Weight) (+/- Standard Deviation) Recorded per Station During the Wet Season Survey.

Site	Total no. of individuals	Total no. of species	Total biomass (g)	Mean no. of individuals	Mean no. of species	Mean biomass (g)
Mirs Bay (MB) (6 stations)	22	10	17.20	3.67±2.8	2.83±2.04	2.87±3.83
Yantian Approach (YA) (6 stations)	35	16	27.26	5.83±2.79	4.33±1.97	4.54±3.96
Tee-off (TO) (6 stations)	27	6	29.70	4.5±3.39	2.17±1.33	4.95±7.55
Wong Chuk Kok Tsui (WCKT) (6 stations)	4	3	4.59	0.67±0.82	0.67±0.82	0.76±1.69
Tolo Channel (TC) (6 stations)	35	9	2.75	5.83±7.6	2.17±2.4	0.46±0.37
Ma Shi Chau (MSC) (6 stations)	6	1	1.37	1.0±0.89	0.67±0.52	0.23±0.19
Tai Po Approach (TPA) (8 stations)	8	1	2.51	1±2.83	0.125±0.35	0.31±0.89
Total no. of individuals	137
Total no. of species		27
Total biomass (g)			85.36

The results of QA/QC identification of the benthic samples passed satisfactorily with the quality check. The results of the benthic samples were re-processed (20% of the sorted and identified samples) by another specialist and matched the list of the species identified during the first identification work.

In general, the species diversity, abundance and biomass of benthos recorded, particularly in Tolo Harbour, were low, and no rare species were recorded in the samples. Comparing the results in both dry and wet seasons surveys, the species diversity, abundance and biomass of benthos recorded during wet season were generally lower. It should be noted that the soft benthos/fauna are typically short lived (less than 2 years) and are able to re-colonise disturbed areas. The initial assessment indicated that, no insurmountable adverse ecological impacts would be expected due to the project as a result of disturbance to benthic fauna.

3.4 SUBTIDAL HARD SURFACE HABITATS

A review of existing coral communities based on the available literature has been presented in Section 2. Based on this information, locations within proximity to the proposed pipelines where coral communities may also exist and are recommended to be surveyed as presented in the following section. Following this, a methodology proposed to be employed at these locations is presented below.

3.4.1 Dive Survey Locations

Based on the review presented in Section 2 nine locations have been identified within proximity to the proposed pipeline route where hard coral communities may exist. These locations are presented below and it is recommended that dive surveys be conducted at these locations:

* Tai Po Landing Point;

* Pak Sha Tau Chau;

* Wong Wan Tsui;

* Fung Wong Fat;

* South Wong Chuk Kok Tsui;

* Wong Chuk Kok Tsui;

* Gruff Head;

* Chek Chau; and,

* Tung Ping Chau.

The above nine locations are presented on Figure 3.4a. Further information on the reason behind the selection of these locations is presented below.

Tai Po Landing Point

Although the findings of the review presented in Section 2 indicated that the Tolo Harbour area did not support hard coral communities, it is recommended that the Tai Po Landing Point be surveyed as direct impacts are expected to occur at this site through the installation of the proposed pipelines. The assessment of direct impacts are a requirement of the Environmental Impact Assessment Ordinance Technical Memorandum (EIAO TM) and as a result, the potential for the Tai Po Landing Point to support hard coral communities must be investigated in order for a detailed assessment of direct impacts to be made. The location of three 50 m transects (A1 to A3) at Tai Po Landing Point are presented on Figure 3.4b.

Pak Sha Tau Chau

The findings of the literature review indicated that Tolo Channel supports hard coral communities of low diversity and coverage. Although these findings were limited to surveys conducted at Bush Reef and Knob Reef, it is recommended that surveys be conducted at Pak Sha Tau Chau due to the locations proximity to the proposed pipeline route (approximately 200m) and Water Supplies Department's water main crossing works. The location of four 50 m transects (B1 to B4) at Pak Sha Tau Chau are presented on Figure 3.4c.

Wong Wan Tsui

The findings of the literature indicated that the north coastline of Tolo Channel at Wong Wan Tsui had been surveyed only qualitatively, however, the results of the surveys found that this area has the potential to support coral communities. As a result, an extensive area is recommended for survey under the present study. The location of nine 50 m transects (C1 to C9) at Wong Wan Tsui survey site are presented on Figure 3.4d.

Fung Wong Fat

Fung Wong Fat is located on the northern shore of the Tolo Approach area opposite to Gruff Head. Although previous surveys have found that there is only limited hard coral cover at Fung Wong Fat (10%), a relatively high number of species were recorded (17). However, as with the proposed Pak Sha Tau Chau site, it is the relative proximity of this location to the proposed pipelines route (approximately 250m) that warrants its inclusion in the presently recommended surveys. The location of six 50 m transects (D1 to D6) at Fung Wong Fat survey site are presented on Figure 3.4e.

South Wong Chuk Kok Tsui

Similarly to the Wong Wan Tsui survey site, the northern coastline between Fung Wong Fat and Wong Chuk Kok Tsui is recommended to be surveyed in order to fill information gaps on the potential for coral communities to exist in this area. In addition, this coastline is in close proximity to the proposed pipelines corridor. The location of nine 50 m transects (E1 - E9) at South Wong Chuk Kuk Tsui are presented on Figure 3.4f.

Wong Chuk Kok Tsui

Although the findings of the review presented in Section 2 did not identify any surveys that were conducted at the Wong Chuk Kok Tsui headland, it is likely from the information available that hard coral communities can be expected to occur at this site. On the basis of this, the proximity of the headland to the proposed pipelines route, Wong Chuk Kok Tsui is recommended to be surveyed to identify any existing corals. The location of six 50 m transects (F1 - F6) at Wong Chuk Kok Tsui survey sites are presented on Figure 3.4g.

Gruff Head

The literature review presented in Section 2 indicated that a recent survey at Gruff Head had reported a coral coverage of 38% with a total of 22 hard coral species. As diversity and coral coverage at this site can be considered to be high when compared to other sites in the vicinity of the proposed pipeline route, it is recommended that Gruff Head be surveyed. Furthermore, Gruff Head is situated on the perimeter of the Hoi Ha Wan Marine Park. Thus, following the assessment of impacts through the installation of the pipelines, if this site is not predicted to experience impacts it is unlikely that the communities at Hoi Ha Wan will be expected to be impacted either. The location of three 50 m transects (G1 - G3) at Gruff Head survey site are presented on Figure 3.4h.

Chek Chau

The northeastern shore of Chek Chau is also recommended for survey. According to the literature, a recent survey conducted in 1998 indicated that this site on Chek Chau supported diverse hard coral communities with high cover (25 species; 60% cover). Although approximately 1,200m from the proposed pipelines, the presence of such high diversity and cover of hard corals warrants this sites inclusion in the presently recommended surveys. The location of six 50 m transects (H1 - H6) at Chek Chau survey site are presented on Figure 3.4i.

Tung Ping Chau

Although the findings of the review presented in Section 2 indicated that hard coral communities are generally restricted to the eastern shoreline of Tung Ping Chau, it is recommended that the northwestern shore be surveyed due to waters around the island being designated as a Marine Park. The location of six 50 m transects (I1 - I6) at Tung Ping Chau survey site are presented on Figure 3.4j.

Additional Survey Sites

The results of the geophysical surveys were examined and found that there are two locations with hard substrates along the proposed pipeline route (Figure 3.4k). Additional surveys were conducted at the sites to investigate the ecological potential of these substrates.

3.4.2 Survey Methodology

Rapid Ecological Assessment Surveys

The Rapid Ecological Assessment technique was employed at each of the survey site in order to investigate the subtidal hard surface assemblages at each site (1). The methodology is discussed below.

The Rapid Ecological Assessment technique allows semi-quantitative information on the ecological attributes of a subtidal habitat to be obtained relatively simply without compromising scientific rigour. An explanation of the methodology proposed to be employed using this technique is presented below.

Location of Transects

Rapid Ecological Assessment surveys were undertaken using SCUBA. At each survey site a corridor for survey has been recommend, the coordinates of which can be extrapolated from the individual survey site figures. An initial qualitative reconnaissance survey was conducted within each of these survey corridors and based on this survey, a decision was made on site as to where to position the transects. Areas where corals appear to be most abundant, or areas of high epifaunal density, were selected as the preferred location. As such, the coordinates of the transects were identified in the field using a portable geographic positioning system (GPS) unit and recorded for future reference.

Number of Transects

The number of transects proposed to be surveyed at each site is presented in Table 3.4a. Each of the transects was 50m in length.

Table 3.4a Recommended Number of Transects to be Surveyed at Each Proposed Survey Site.

Proposed Survey Site	Number of 50m Transects to be Surveyed in the Corridor	Total Length of Area to be Surveyed
Tai Po Landing Point	3	150m
Pak Sha Tau Chau	4	200m
Wong Wan Tsui	9	450m
Fung Wong Fat	6	300m
Gruff Head	3	150m
South Wong Chuk Kok Tsui	9	450m
Wong Chuk Kok Tsui	6	300m
Chek Chau	6	300m
Tung Ping Chau	6	300m
Total	52	2,600m

Transect Depth

Three distinct depths zones were surveyed as follows:

* Shallow depth zone: -2 to -5mCD;

* Middle depth zone: -5 to -10mCD; and,

* Deep depth zone: -10 to -13mCD.

The depth of the transects was adjusted accordingly based on the substrate habitat and the presence or absence of hard and soft corals.

Assessment Techniques

Following the laying of the transect line, video footage taken of the benthos along the transect was taken and an assessment of the benthic cover (Tier I) and taxon abundance (Tier II) undertaken in a swathe ~ 4 m wide, 2 m either side of each transect. An explanation of the two assessment categories (Tiers) to be used in the survey is presented below.

Tier I - Categorisation of Benthic Cover

Upon the completion of the survey at each transect, six ecological and seven substratum attributes shall be assigned to one of seven standard ranked (ordinal) categories (Tables 3.4b and 3.4c).

Table 3.4b Categories to be used in the Surveys - Benthic Attributes

Ecological	Substratum
Hard coral	Hard substrate
Dead standing coral	Continuous pavement
Soft coral	Bedrock
Antipatharia	Rubble
Macroalgae	Sand
Turf algae	Silt
	Boulders - large (>50 cm), small (<50 cm)

Table 3.4c Categories to be used in the Surveys - 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	75-100

Tier II - Taxonomic Inventories to Define Types of Benthic Communities

An inventory of benthic taxa (including counts of coral colonies) was compiled for each transect. Taxa were identified in situ to the following levels:

* Scleractinian (hard) corals to species wherever possible.

* Soft corals, Antipatharia, anemones and conspicuous macroalgae shall be recorded according to morphological features and to genus level where possible.

* Other benthos (including sponges, zoanthids, ascidians and bryozoans) shall be recorded to genus level wherever possible or phylum plus growth form.

Following the completion of the survey at each transect, each taxon in the inventory was ranked in terms of abundance in the community (Table 3.4d). 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 3.4d Ordinal Ranks of Taxon Abundance

Rank	Abundance
0	Absent
1	Rare*
2	Uncommon
3	Common
4	Abundant
5	Dominant

Note: * The classification of "rare" abundance refers to low abundance (small quantity) on the transect, rather

than in terms of distribution in Hong Kong waters.

Photographs of representative hard and soft coral species located in the surveyed areas were taken (ensuring that a photographic record, in digital format, of each species is provided). Video footage of each transect were also saved in MPEG or VCD format.

3.4.3 Results

Survey Dates and Conditions

The dive surveys were carried out in the wet season during 19th - 29th July 2002. Throughout the survey period, the sea conditions were generally clam with flat seas. The occasional isolated thunderstorm and storm winds did create choppy water conditions at Chek Chau and Wong Chuk Kok Tsui.

Physical Description of the Survey Sites

The majority of the northern coastline from Pak Sha Tau Chau to Wong Chuk Kok Tsui is a continuous linear stretch of undisturbed boulder shoreline, occasionally broken by a pebble beach or a small bay. Tai Po Landing Point consisted of an artificial seawall and concrete pier. Gruff Head is a rocky peninsula bordering Hoi Ha Wan Marine Park. Chek Chau is predominantly a boulder shoreline with a pebble beach. The northwest side of Tung Ping Chau is mainly steep sided cliffs of Mesozoic to Cenozoic sedimentary rock, composed of dolomitic siltstone similar to the rest of the island as described by Lai et al. (1)

Tai Po Landing Point

Tai Po Landing Point consisted primarily of large boulders (part of the artificial seawall) or concrete blocks (from the pier) and natural hard substrate (large rocks) extending out to a depth of - 4 m CD (Table 3.4e). The surrounding seabed consisted of mud/silt (anoxic) and pockets of shell fragments. Hard substrate was encrusted by the large solitary tunicate (Styela plicata) which dominated the benthic taxa recorded. Sparse and small colonies of the faviid Oulastrea crispata (typically colonies of <8 corallites), barnacles, oysters and Perna viridis were also recorded (Table 3.4f). The silt seabed was barren with the exception of numerous tube anemones (Cerianthid sp.). Five individual seahorses Hippocampus kuda were also recorded during the survey.

Table 3.4e Seabed Attributes Along the Survey Transects A1 to A3

	A1	A2	A3
Seabed attributes ^a
Hard substrate
Continuous Pavement
Bedrock
Rubble
Sand
Silt
Large boulders (>50 cm)	3	3	2
Small boulders (<50 cm)	2	2	3
Ecological attributes ^a
Hard coral	1	1
Dead standing coral
Soft coral
Antipatharia
Macroalgae
Turf algae
Average Depth (m)	3.1	2.7	2.8

a Note: 1 = <5% Cover, 2 = 6-10% Cover, 3 = 11-30% Cover, 4 = 31-50% Cover, 5 = 51-75% Cover, 6 = 76-100%Cover.

Table 3.4f Benthic species Recorded Along the Survey Transects A1 - A3

	A1	A2	A3
Hard Coral
Oulastrea crispata	3	2	0
Others
Tube anemones Cerianthids	0	0	2
Ascidian Styela plicata	4	4	4
Rock oyster Saccostrea sp	2	2	3
Sea urchin Salmacis sphaeroides	0	0	2

a Note: 1 = <5% Cover, 2 = 6-10% Cover, 3 = 11-30% Cover, 4 = 31-50% Cover, 5 = 51-75% Cover, 6 = 76-100%Cover.

Pak Sha Tau Chau

A narrow band of boulders in the shallow sub-littoral zone grading to a sandy seabed (below 3 m CD depth) with scattered boulders was recorded (Table 3.4g). From a depth of -4 m CD the seabed was composed of anoxic silt with limited benthic taxa recorded.

The sessile benthic taxa predominate on boulders was composed of fouling organisms such as sponges (Callyspongia sp. and Tethya sp.), bryozoans (Schizoporella errata), rock oysters (Saccostrea sp.), Perna viridis and the tunicate Styela plicata. Sea urchins including Diadema setosum and Salamacis sphaeroides (decorator urchin) were also recorded (Table 3.4h). The faviid Oulastrea crispata was the only hard coral species recorded and this occurred in the shallow and middle depth zones. Tube anemones (Cerianthids) were also abundant in the middle depth zone.

One small (<10 cm) colony of Goniopora sp. was noted near Transect B1 at a depth of -4 m CD and this coral colony's appearance indicated some degree of stress with retracted polyps and bloated live tissue (a sediment removal mechanism). The Antipatharia Antipathes sp. was recorded in low coverage and abundance on Transect B4 only. In addition a small aggregation (~ six large colonies) of Antipatharia Antipathes sp. was noted near Transects B2 and B3 at a greater depth of -7 to -8 m CD.

Table 3.4g Seabed Attributes Along the Survey Transects B1 to B4

	B1	B2	B3	B4
Seabed attributes ^a
Hard substrate
Continuous Pavement
Bedrock
Rubble
Sand	4	4	5	4
Silt
Large boulders (>50 cm)	3	3	3	4
Small boulders (<50 cm)	1	2	2	2
Ecological attributes ^a
Hard coral		1	1	1
Dead standing coral
Soft coral		3
Antipatharia				2
Macroalgae
Turf algae
Average Depth (m)	2.3	2.2	3.0	4.5

a Note: 1 = <5% Cover, 2 = 6-10% Cover, 3 = 11-30% Cover, 4 = 31-50% Cover, 5 = 51-75% Cover, 6 = 76-100%Cover.

Table 3.4h Benthic species Recorded Along the Survey Transects B1 - B4

	B1	B2	B3	B4
Hard Coral
Oulastrea crispata	0	2	2	2
Soft Coral
Euplexaura sp.	0	4	0	0
Antipatharia
Antipathes sp.	0	0	0	2
Others
Tube anemones Cerianthids	1	3	3	0
Bryozoans Schizoporella errata	1	0	2	0
Cnidaria Aiptasia sp.	3	4	2	3
Ascidian Styela plicata	2	3	3	3
Mussel Perna viridis	0	0	3	3
Rock oyster Saccostrea sp	0	4	4	4
Sea urchin Diadema setosum	4	3	3	3
Sea urchin Salmacis sphaeroides	3	3	0	0
Holothurians Holothuria leucospilota	1	0	2	2
Unidentified encrusting Porifera	3	3	3	3
Porifera Callyspongia sp.	3	0	0	0
Porifera Tethya sp.	2	2	2	0

a Note: 1 = <5% Cover, 2 = 6-10% Cover, 3 = 11-30% Cover, 4 = 31-50% Cover, 5 = 51-75% Cover, 6 = 76-100%Cover.

Wong Wan Tsui

Two distinct assemblages of benthic taxa were identified at this location. The shallow depth zone consisted of large boulders covered predominately by fouling organisms such as the rock oyster (Saccostrea sp.), the sponge Schizoporella errata, aggregated brown anemone (Aiptasia sp.) and Perna viridis (Tables 3.4i and 3.4j). A total of 21 hard coral species were recorded in the shallow zone and were represented by Acropora pruinosa, Porites sp., Goniopora spp., Montipora spp., Pavona decussata, Psammocora spp. and faviids such as Cyphastrea spp., Plesiastrea versipora and Oulastrea crispata. Coral colonies were generally small with the exception of large isolated P. versipora colonies and the majority of colonies exhibited high levels of bioerosion (moderate - high abundance of juvenile sea urchins Diadema setosum were recorded). Live hard coral cover was sparse (<5 %). The shallow zone of the most eastern extent of this location contained the abundant large branching sponge (Sigmadocia symbiotica).

Within the middle depth zone the seabed was composed of sand and scattered small - large boulders and dead hard coral. Sparse, small and encrusting hard corals (a total of 14 species) and large Antipatharia colonies (Antipathes sp. and Cirripathes sp.) were the main components of this deeper community.

The large colonies of Antipathes sp. reached heights of >1 m and appeared to be refuge areas for a variety of marine life particularly fish and squid. Most colonies were fouled by bryozoans, sponges and the pearl winged oyster (Pteria cf penguin); all commonly associated with antipatharians. Cirripathes sp. was less abundant but sustained a large size (>1 m in height).

This area of Inner Tolo Channel contained a surprisingly high number of hard corals (24 species in total) with two locally uncommon coral species (Goniopora cellulosa and Montipora mollis) being recorded for this region of Hong Kong.

Table 3.4i Seabed Attributes Along the Survey Transects C1 to C9

	C1	C2	C3	C4	C5	C6	C7	C8	C9
Seabed attributes ^a
Hard substrate
Continuous Pavement
Bedrock
Rubble
Sand		2	6	5	3	5	4	4
Silt
Large boulders (>50 cm)	4	5	2	3	4	3	3	4	3
Small boulders (<50 cm)	4								2
Ecological attributes ^a
Hard coral	1	1	1	1	1	1	1	1	1
Dead standing coral	1			2		2	2	2	2
Soft coral
Antipatharia	4	2	3	3	2	3	4	1	1
Macroalgae
Turf algae
Average Depth (m)	6.8	3.5	5.1	6.1	3.0	6.1	5.9	3.1	2.4

a Note: 1 = <5% Cover, 2 = 6-10% Cover, 3 = 11-30% Cover, 4 = 31-50% Cover, 5 = 51-75% Cover, 6 = 76-100%Cover.

Table 3.4j Benthic species Recorded Along the Survey Transects C1 to C9

	C1	C2	C3	C4	C5	C6	C7	C8	C9
Hard Coral
Acropora pruinosa	0	1	0	0	1	0	0	1	0
Montipora venosa	0	1	0	0	0	0	0	0	0
Montipora peltiformis	0	1	0	0	0	0	0	0	0
Montipora mollis	0	2	0	0	1	0	0	0	0
Psammocora superficialis	2	0	0	0	2	0	0	1	0
Psammocora haimeana	2	1	0	0	0	2	0	2	1
Coscinaraea monile	0	0	0	0	0	1	0	0	0
Pavona decussata	1	2	0	0	1	1	0	1	0
Lithophyllon undulatum	0	1	0	0	0	0	0	0	0
Turbinaria peltata	1	1	0	0	0	0	0	0	0
Favia lizardensis	0	0	0	0	0	0	1	0	0
Favia maritima	0	0	0	0	0	2	0	0	0
Favia rotumana	0	0	0	0	0	0	0	1	0
Favites chinensis	0	0	0	0	0	0	0	1	0
Plesiastrea versipora	0	0	0	3	0	1	3	3	2
Oulastrea crispata	3	3	2	3	3	3	3	3	3
Leptastrea purpurea	0	2	0	0	0	0	0	0	0
Cyphastrea serailia	2	2	0	0	2	2	2	2	2
Porites lobata or P. lutea	0	3	0	0	3	3	0	2	0
Porites deformis	0	0	0	0	1	0	0	1	0
Goniopora cellulosa	0	0	0	0	0	0	0	0	1
Goniopora stutchburyi	2	2	0	0	0	2	0	1	1
Goniopora fruticosa	2	2	0	0	0	0	0	0	0
Stylocoeniella guentheri	0	0	0	0	0	0	1	1	0
Antipatharia
Antipathes sp.	4	2	3	3	3	3	4	1	2
Cirripathes sp.	2	0	0	2	2	1	2	0	0
Others
Tube anemones Cerianthids	2	2	3	2	2	2	2	2	0
Bryozoans Schizoporella errata	0	0	0	2	2	0	2	0	0
Cnidaria Aiptasia sp.	0	3	0	0	3	2	0	3	3
Cnidaria Heteractis sp.	0		0	0	0	1	2	0	0
Ascidian Styela plicata	0	0	0	0	0	0	0	2	0
Mussel Perna viridis	0	0	0	0	0	0	0	0	2
Rock oyster Saccostrea sp	2	4	0	3	4	3	2	3	4
Bivalve Atrina pectinata	2	0	0	0	0	0	0	2	0
Bivalve Pterina cf penquin	0	0	0	2	0	0	0	0	0
Sea urchin Diadema setosum	3	4	2	3	4	3	0	3	3
Holothurians Holothuria leucospilota	2	2	0	2	2	0	2	2	3
Holothurians Holothuria arenicola	0	0	0	0	0	2	0	2	3
Unidentified encrusting Porifera	2	3	2	2	0	2	0	2	2

a Note: 1 = <5% Cover, 2 = 6-10% Cover, 3 = 11-30% Cover, 4 = 31-50% Cover, 5 = 51-75% Cover, 6 = 76-100%Cover.

Fung Wong Fat

REA transects were positioned alongside the two headlands of Fung Wong Fat. Two distinct benthic assemblages were recorded. These consisted of a shallow assemblage predominantly composed of fouling organisms and sparse hard corals and the middle depth assemblage that was a continuation of the Antipatharia community described from Wong Wan Tsui. Hard coral species richness and percentage cover of Antipatharia were high as compared to data recorded from Wong Wan Tsui.

The shallow depth zone composed of large boulders encrusted with oysters (Saccostrea sp.), zoanthid mats (Zoanthus sp.) in association with sparse, small hard coral colonies (Tables 3.4k & 3.4l). A total of 22 hard coral species were recorded with highest species richness noted for Transect D6. Live coral cover was extremely low (<5 %) and species composition consisted of Pavona decussata, Porites sp., Goniopora sp., Psammocora spp., Montipora spp., Lithophyllon undulatum, Stylocoeniella guentheri and faviids such as Favia spp., Cyphastrea spp. and Leptastrea sp. Antipatharia colonies were recorded in the deeper ranges of the shallow depth zone.

The middle depth zone was composed of large boulders (in the shallower range) changing to a sand seabed with scattered boulders and dead hard coral cover. Hard coral species richness and cover were similar to the shallow depth zone with 21 species (similar composition as well) and <5 % cover. Sparse colonies of the ahermatypic coral Tubastrea sp. were also recorded. Antipatharia dominated this middle zone community.

One extremely large (>2 m diameter) Plesiastrea versipora colony was recorded at Transect D2 and isolated massive colonies (>50 cm) were also noted in the middle depth zone amongst Antipatharia colonies.

The deep depth zone assemblage was composed of large Antipathes sp. and Cirripathes sp. with lower hard coral species richness and cover than the other zones.

Table 3.4k Seabed Attributes Along the Survey Transects D1 to D6

	D1	D2	D3	D4	D5	D6
Seabed attributes ^a
Hard substrate
Continuous Pavement
Bedrock
Rubble
Sand	3	3	4	4	5	4
Silt
Large boulders (>50 cm)	3	4	3	3	3	3
Small boulders (<50 cm)	2	2	2	3	2	3
Ecological attributes ^a
Hard coral	1	1	1	1	1	6
Dead standing coral	1	1	2	2	1	2
Soft coral	1	1	1	1
Antipatharia	4	3	3	3	3	3
Macroalgae
Turf algae
Average Depth (m)	9.8	6.7	4.9	10.4	6.9	4.4

a Note: 1 = <5% Cover, 2 = 6-10% Cover, 3 = 11-30% Cover, 4 = 31-50% Cover, 5 = 51-75% Cover, 6 = 76-100%Cover.

Table 3.4l Benthic species Recorded Along the Survey Transects D1 to D6

	D1	D2	D3	D4	D5	D6
Hard Coral
Montipora peltiformis	0	0	0	0	0	1
Montipora mollis	0	0	0	0	2	2
Psammocora superficialis	2	2	2	0	3	3
Psammocora haimeana	0	0	0	0	1	2
Pavona decussata	0	1	2	0	1	3
Lithophyllon undulatum	0	0	0	0	1	2
Turbinaria peltata	0	1	1	0	2	0
Favia speciosa	0	1	0	0	2	0
Favia lizardensis	0	1	0	0	0	1
Favia maritima	1	1	2	0	1	2
Favia rotumana	0	2	0	0	0	0
Favites chinensis	1	0	0	1	2	3
Goniastrea aspera	0	0	1	0	0	2
Plesiastrea versipora	3	3	3	0	2	3
Oulastrea crispata	3	3	4	4	4	4
Leptastrea purpurea	0	0	2	0	0	0
Leptastrea pruinosa	0	0	0	0	0	2
Cyphastrea serailia	0	2	0	0	3	3
Cyphastrea chalcidicum	0	0	0	0	0	2
Coscinaraea monile	0	0	0	2	0	0
Balanophyllia sp	2	0	0	0	0	0
Tubastrea/Dendrophyllia sp	2	0	0	3	0	0
Porites lobata or P. lutea	2	2	3	0	0	3
Goniopora columna	0	1	0	1	0	2
Goniopora stutchburyi	3	2	0	1	3	2
Goniopora fruticosa	2	2	1	0	3	0
Stylocoeniella guentheri	0	0	0	0	2	2
Soft Coral
Dendronephthya sp	0	0	0	1	0	0
Echinomuricea sp	2	0	0	2	0	0
Echinogorgia sp	2	0	0	0	0	0
Euplexaura sp.	0	1	1	0	0	0
Antipatharia
Antipathes sp.	4	3	2	4	3	3
Cirripathes sp.	2	2	0	2	2	0
Others
Tube anemones Cerianthids	0	0	1	2	2	2
Bryozoans Schizoporella errata	0	2	0	0	0	0
Cnidaria Aiptasia sp.	2	0	2	0	2	2
Cnidaria Entacmaea quadricolor.	0	2	0	0	2	0
Mussel Perna viridis	0	1	0	0	0	0
Rock oyster Saccostrea sp	4	3	3	3	3	0
Bivalve Atrina pectinata	0	2	2	0	0	0
Bivalve Pterina cf penguin	3	3	0	3	3	0
Sea urchin Diadema setosum	4	4	4	0	3	4
Sea urchin Salmacis sphaeroides	0	0	3	0	0	0
Holothurians Holothuria leucospilota	0	3	3	0	2	3
Holothurians Colochirus crassus	2	0	0	0	0	0
Unidentified encrusting Porifera	0	2	3	3	3	0
Porifera Callyspongia sp	0	2	0	0	0	0

a Note: 1 = <5% Cover, 2 = 6-10% Cover, 3 = 11-30% Cover, 4 = 31-50% Cover, 5 = 51-75% Cover, 6 = 76-100%Cover.

South Wong Chuk Kok Tsui

The two distinct communities identified in the shallow and middle depth zones at Fung Wong Fat continued along South Wong Chuk Kok Tsui with an increase in coral community development in the shallows zones i.e. large faviid colonies were recorded. Hard coral species richness and percentage cover increased towards the eastern extent of South Wong Chuk Kok Tsui with the deeper Antipatharia assemblage also continuing.

The shallow depth zone community was composed of a narrow band (~5 m wide) of hard corals on large boulders and a variety of fouling organisms (as similarly recorded from Inner Tolo Channel locations) (Tables 3.4m & 3.4n). A total of 45 hard coral species were recorded of which 44 were noted from the shallow zone and 30 from the middle zone. Hard coral cover was between 11-30 % with small patches of higher coverage (~50 %). Large faviids such as Platygyra acuta and Favia spp., poritids such as Porites sp. and Goniopora spp. dominated the hard coral assemblages. Some coral colonies in the shallow zones appeared highly bioeroded and damaged from toppling and possibly dynamiting.

The middle depth zone was dominated by large Antipathes sp., a lower abundance of Cirripathes sp. and sparse hard coral colonies of low percentage cover (<10 %) but high species richness.

One individual seahorse (Hippocampus kuda) was recorded near Transect E8.

Table 3.4m Seabed Attributes Along the Survey Transects E1 to E9

	E1	E2	E3	E4	E5	E6	E7	E8	E9
Seabed attributes ^a
Hard substrate
Continuous Pavement
Bedrock
Rubble				1
Sand	5	3	4	4	2	3	3	5	2
Silt
Large boulders (>50 cm)	3	4	3	3	5	4	4	2	4
Small boulders (<50 cm)	2	1	1	2	2	1	1	3	2
Ecological attributes ^a
Hard coral	1	1	1	3	3	3	2	2	3
Dead standing coral	1	1	1	2	2	2	2	2	2
Soft coral	1			1		1	1	1
Antipatharia	3	2	2				3	2
Macroalgae
Turf algae
Average Depth (m)	8.7	4.3	5.8	2.1	3.0	1.8	5.1	8.0	4.3

a Note: 1 = <5% Cover, 2 = 6-10% Cover, 3 = 11-30% Cover, 4 = 31-50% Cover, 5 = 51-75% Cover, 6 = 76-100%Cover.

Table 3.4n Benthic species Recorded Along the Survey Transects E1 to E9

	E1	E2	E3	E4	E5	E6	E7	E8	E9
Hard Coral
Acropora japonica	0	0	0	2	0	0	0	0	0
Acropora pruinosa	0	1	0	1	1	1	0	0	1
Montipora peltiformis	1	1	0	1	1	0	0	0	2
Montipora millepore	0	0	0	0	0	0	0	0	0
Montipora mollis	0	1	0	0	0	0	0	0	0
Psammocora superficialis	0	0	2	0	0	2	3	2	2
Psammocora haimeana	2	0	0	1	0	0	0	0	0
Coscinaraea monile	0	1	1	0	0	0	1	2	1
Pavona decussata	2	1	0	2	2	2	2	2	2
Lithophyllon undulatum	0	0	1	0	2	0	1	2	2
Echinophyllia aspera	0	0	0	2	2	3	0	0	0
Hydnophora exesa	0	0	0	2	2	2	0	3	3
Turbinaria peltata	0	0	1	2	3	2	3	3	2
Micromussa amakusensis	0	0	0	2	0	0	0	0	0
Acanthastrea echinata	0	0	0	2	2	3	0	0	3
Acanthastrea lordhowensis	0	0	0	0	2	0	0	0	0
Acanthastrea hemprichii	0	0	0	0	2	2	0	0	0
Balanophyllia sp	0	0	0	0	0	0	0	1	0
Favia rotumana	0	0	0	3	3	3	2	3	3
Favia danae	0	0	0	0	0	0	0	0	0
Favia speciosa	0	0	2	0	0	2	2	2	0
Favia lizardensis	0	0	0	3	0	0	0	0	3
Favia veroni	0	0	2	2	0	2	0	0	0
Favia maritima	0	1	3	0	2	0	3	3	2
Favites pentagona	0	0	1	3	3	3	0	0	3
Favites chinensis	0	0	3	3	3	3	0	2	3
Favites abdita	0	0	0	1	0	2	0	2	2
Favites halicora	0	0	0	2	2	2	0	0	2
Favites acuticollis	0	0	0	1	1	0	0	0	0
Goniastrea aspera	0	0	0	2	2	0	0	0	0
Platygyra carnosus	0	0	1	3	3	2	0	0	2
Platygyra acuta	0	0	0	2	4	4	0	0	4
Montastrea curta	0	0	0	1	0	0	0	0	1
Plesiastrea versipora	2	3	3	3	0	0	3	3	3
Oulastrea crispata	3	3	3	3	0	0	3	4	3
Leptastrea purpurea	1	0	0	0	2	0	0	2	0
Leptastrea pruinosa	0	0	0	2	0	0	0	2	0
Cyphastrea serailia	2	0	2	0	2	3	0	3	3
Porites lobata or P. lutea	2	2	1	2	2	2	0	3	2
Gonipora columna	0	2	2	2	2	2	0	0	3
Gonipora djiboutiensis	0	0	0	0	0	0	2	0	0
Gonipora lobata	0	0	0	1	0	0	0	3	0
Goniopora stutchburyi	1	2	0	0	2	0	2	0	0
Goniopora fruticosa	0	2	0	2	0	0	1	3	0
Stylocoeniella guentheri	0	1	2	0	0	0	2	3	3
Soft Coral	&nb