5. ECOLOGICAL IMPACT

Introduction

5.1 This section identifies and evaluates the nature and extent of potential impacts resulting from the Project on marine ecological resources in the assessment area. Relevant baseline studies and assessment reports were reviewed and both direct and indirect impacts on ecology during construction and operation phases were included in the assessment.

5.2 Field surveys were undertaken to check the current ecological baseline conditions. Ecological importance of habitats and species potentially affected by the proposed works was identified and assessed. The scale and significance of possible ecological impacts resulting from the Project was evaluated, and necessary mitigation measures were recommended. Residual and cumulative ecological impacts were also identified and evaluated, and ecological monitoring and audit requirements were discussed.

Environmental legislation, policies, plans, standards and criteria

5.3 This assessment makes reference to the following HKSAR Government ordinances, regulations, standards, guidelines, and documents when identifying ecological importance of habitats and species, evaluating and assessing potential impacts of the Project on the ecological resources:

Ÿ Environmental Impact Assessment Ordinance (EIAO) (Cap. 499) – aims to avoid, minimize and control the adverse effects on the environment by designated projects through the application of the environmental impact assessment process and the environmental permit system.

Ÿ Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM) Annex 8 – recommends the criteria that can be used for evaluating habitat and ecological impact.

Ÿ EIAO-TM Annex 16 – sets out the general approach and methodology for assessment of ecological impacts arising from a project or proposal, to allow a complete and objective identification, prediction and evaluation of the potential ecological impacts.

Ÿ EIAO Guidance Note No. 3/2010 – provides guiding principles on the approach to assess the recommended environmental mitigation measures in EIA reports.

Ÿ EIAO Guidance Note No. 6/2010 – clarifies the requirement of ecological assessments under the EIAO.

Ÿ EIAO Guidance Note No. 7/2010 – provides general guidelines for conducting ecological baseline surveys in order to fulfill requirements stipulated in the EIAO-TM.

Ÿ EIAO Guidance Note No. 11/2010 – introduces some general methodologies for marine ecological baseline surveys.

Ÿ Wild Animals Protection Ordinance (Cap. 170) – designated wild animals are protected from being hunted, whilst their nests and eggs are protected from injury destruction and removal. All birds and most mammals, including marine cetaceans, are protected under this Ordinance. The Second Schedule of the Ordinance, which lists all the animals protected, was last revised in June 1997.

Ÿ Town Planning Ordinance (Cap. 131) – provides for the designation of coastal protection areas, Sites of Special Scientific Interest (SSSIs), Conservation Area, Country Park, Green Belt or other specified uses that promote conservation or protection of the environment.

Ÿ Chapter 10 of the Hong Kong Planning Standards and Guidelines (HKPSG) – covers planning considerations relevant to conservation. This chapter details the principles of conservation, the conservation of natural landscape and habitats, historic buildings, archaeological sites and other antiquities. It also describes enforcement issue. The appendices list the legislation and administrative controls for conservation, other conservation related measures in Hong Kong and government departments involved in conservation.

Ÿ The Marine Parks Ordinance (Cap. 476) and Subsidiary Legislation – allows for designation, control and management of marine parks and marine reserves through regulation of activities therein to protect, conserve and enhance the marine environment for the purposes of nature conservation, education, scientific research and recreation. The Ordinance came into effect on 1 June 1995.

Ÿ The Protection of the Harbour Ordinance (Cap. 531) – bases on a presumption against reclamation, the harbour is to be protected and preserved as a special public asset and a natural heritage of Hong Kong people.

Ÿ The Water Pollution Control Ordinance (Cap. 358) – aims to control water pollution in waters of Hong Kong. Water control zones are designated with individual water quality objective to promote the conservation and best use of those waters in the public interest. The most updated water quality objectives for the Victoria Harbour Water Control Zone were revised in June 1997.

5.4 This assessment also makes reference to the following international conventions and nearby national regulation:

Ÿ International Union for Conservation of Nature and Natural Resources (IUCN) 2008 Red Data Books – provides taxonomic, conservation status and distribution information on threatened species that have been evaluated using the IUCN Red list Categories and Criteria. This system is designed to determine the relative risk of extinction, and the main purpose of the IUCN Red List is to catalogue and highlight those taxa that are facing a higher risk of global extinction.

Ÿ The PRC National Protection Lists of Important Wild Animals and Plants – lists detailed Category I and Category II key protected animals and plant species under Mainland Chinese Legislation. The list was last updated in November 2002.

Assessment Methodology

Assessment Area

5.5 In accordance with Clause 3.4.7.2 of the EIA Study Brief (ESB-193/2008), marine ecological impact assessment is required only if there are proposed marine works that would disturb the seabed. The assessment area for the marine ecological impact assessment shall be the same as that for the water quality impact assessment, or the area likely to be impacted by the Project, which covers the Victoria Harbour Water Control Zone (WCZ), the Eastern Buffer WCZ and the Western Buffer WCZ, as declared under the Water Pollution Control Ordinance (WPCO), any areas within a distance of 300 m from the Project boundary and from any works sites, including works sites away from the railway route, and other areas such as existing and new drainage system and any associated water system(s) affected by the construction and operation of the Project and associated works, including any phased implementation. The assessment area may be extended to include other areas being impacted such as stream courses and the associated water systems in the vicinity.

5.6 Whilst, it is stipulated in Clause 3.4.7.3 of the EIA Study Brief that terrestrial/freshwater ecological impact assessment is required only if off-site works area would encroach or affect recognized sites of conservation importance such as country parks, Sites of Special Scientific Interests (SSSI) and important habitats as stated in Annex 8 of the TM.

5.7 The off-site works area away from the railway route includes immersed tube (IMT) casting basin at ex-Shek O Quarry. The ex-Shek O Quarry comprised of two habitats namely Developed Area/ Disturbed Area and Plantation habitat. Developed Area/ Disturbed Area included the access road, the site office, the mining area and the associated facilities. Plantation habitat encompassed the roadside plantation along the traffic road, amenity planting on engineering slopes and the plantation area. These areas were dominated by exotic tree species such as Acacia confusa, Acacia auriculiformis, Acacia mangium, Leucaena leucocephala and Eucalyptus sp., as well as some native shrub or tree (i.e. Gordonia axillaris, Mallotus paniculatus, Schefflera heptaphylla, Macaranga tanarius, Litsea glutinosa and Rhodomyrtus tomentosa) The floral diversity was low and the age was young.

5.8 The ex-Shek O Quarry will be used as a fabrication works site with a concrete batching plant. Although Shek O Country Park and D’ Aguilar Peninsula SSSI are about 20 m and 100 m away respectively, they are separated from the proposed works area by traffic road and a steep tall slope of plantation area. The proposed construction works is similar in nature to the previous quarrying works and is relatively small in scale, and would not affect the nearby country park and SSSI.

5.9 Since the off-site works area would not encroach or affect any recognised sites of conservation importance such as country parks, SSSI, and important habitats as stated in Annex 8 of the TM, terrestrial/freshwater ecological impact assessment is not required in accordance with Clause 3.4.7.3 of the EIA Study Brief.

Literature Review

5.10 In accordance with Clause 3.4.7.5 (i) of the EIA Study Brief, a review of the findings of relevant studies and collation of all the available information regarding the ecological character of the assessment area were carried out. The information collated was evaluated to provide the ecological baseline information and identify any information gap relating to the assessment of potential ecological impacts to the terrestrial and aquatic environment.

Ecological Surveys

5.11 Ecological field surveys were conducted to supplement and check the validity of data collected through the literature review process, which covered coral, subtidal soft bottom benthic communities, intertidal communities. Figure Nos. NEX2213/C/331/ENS/M51/003, NEX2213/C/331/ENS/M51/004 and NEX2213/C/331/ENS/M51/011 illustrate the locations of ecological surveys conducted under this EIA study. Table 5.1 presents the schedule of the ecological surveys. Results of the surveys are summarized in Description of the Environment section and detailed in full in Appendices 5.1 to 5.3.

Table 5.1 Ecological Survey Programme

Ecological Survey		2009
		Dry Season		Wet Season							Dry Season
	Site^(1)	Feb	Mar	Apr	May	Jun	Jul	Aug	Sept	Oct	Nov	Dec
Spot-check Dive Survey for Coral	VHR/ HUH	ü	ü
	CBTS							ü
	SKO							ü
REA for Coral	VHR/ HUH				ü
	CBTS^(2)
	SKO									ü
Sampling of Subtidal soft bottom benthic Communities	VHR/ HUH	ü			ü
	CBTS							ü			ü
	SKO							ü			ü
Survey on Intertidal Communities	VHR/ HUH	ü	ü		ü
	CBTS							ü			ü
	SKO							ü				ü

Note:

(1) Site: VHR/HUH = Mid Victoria Harbour/Hung Hom; CBTS = Causeway Bay Typhoon Shelter, Southeast Corner; SKO = Shek O Quarry.

(2) Since no coral was found at CBTS in spot check dive survey, REA survey is not necessary.

Impact Assessment Methodology

5.12 High ecological value habitats and species of conservation importance within the assessment area were identified with reference to Annex 8 and 16 of the EIAO-TM. Assessment of ecological impacts was based on criteria described in Annex 8 of the EIAO-TM. Potential direct, indirect, on-site, off-site, primary, secondary and cumulative ecological impacts were identified, quantified where possible, and assessed, with particular attention paid to key ecological sensitive receivers (e.g. coral site).

5.13 Both direct impact of habitats loss and indirect impacts due to change in water quality and hydrodynamic condition arising from the Project and the subsequent impact on marine life were included in the ecological assessment. The assessment was based on available updated ecological information and results from water quality modelling and covered both construction and operation phase impacts.

5.14 Potential cumulative impacts due to concurrent projects or pollution sources within the assessment area were identified and evaluated.

5.15 If impacts on ecological resources are found to be significant, mitigation measures would be recommended in accordance with Annex 16 of the EIAO-TM and EIAO Guidance Note No. 3/2010. Impact mitigation would be sought in the following priority: avoidance, minimization, on-site compensation, and off-site compensation.

5.16 Any residual ecological impact after implementation of mitigation measures were addressed and evaluated. Requirement of ecological monitoring was discussed and recommended as appropriate.

Description of the Environment

5.17 The ecological baseline conditions in the assessment area are described below.

5.18 Location of the key ecological resources within the assessment area are shown in Figure No. NEX2213/C/331/ENS/M51/002.

Areas of Conservation Interest

5.19 Shek O Country Park and D’ Aguilar Peninsula SSSI are located about 20 m and 100 m away from the proposed Shek O IMT casting basin respectively. However, they are separated from the proposed work site by a traffic road and a tall steep slope of green belt.

5.20 Shek O Country Park covering 701 ha land area was designated in 1979 (AFCD, 2010a). Native shrubs and trees such as Hong Kong Gordonia (Gordonia axillaris), Machilus species, Ivy Tree (Schefflera heptaphylla), Aporusa (Aporusa dioica), and Rose Myrtle (Rhodomyrtus tomentosa), rare plants like Buddhist Pine (Podocarpus macrophyllus) and Blue Japanese Oak (Cyclobalanopsis glauca) can be found there. It, particularly the woodland habitats, contains a variety of mammal species including Musk Shrew (Suncus murinus), Chestnut Spiny Rat (Niviventer fulvescens), Chinese Ferret Badger (Melogale moschata), Masked Palm Civet (Paguma larvata), Small Indian Civet (Viverricula indica), Chinese Porcupine (Hystrix brachyura), Chinese Leopard Cat (Prionailurus bengalensis) and Red Muntjac (Muntiacus muntjak). It is also home to many birds. Common species are Buzzard (Buteo buteo), White-bellied Sea Eagle (Haliaeetus leucogaster), Chinese Francolin (Francolinus pintadeanus), Barn Swallow (Hirundo rustica), House Swift (Apus affinis), Violet Whistling Thrush (Myophonus caeruleus), and Black Drongo (Dicrurus macrocercus),

5.21 D’ Aguilar Peninsula SSSI is situated southeast of the proposed IMT casting basin. It was designated in 1975 (PlanD, 1995) with an area of 5 ha. The SSSI contains three plant species of conservation interest, which include the rare plant of Quercus glauca and Keteleeria fortunei, and the law-protected orchid Acampe multiflora. The colonies of the former two at the site are the last known remaining wild stock of the species in Hong Kong.

5.22 There are no other SSSIs, Marine Parks / Reserves or other areas of ecological importance or conservation interest, in the proposed marine-based works area and its vicinity. However, far field ecological sensitive receivers were identified, which include:

· Coral areas located at Green Island, and Little Green Island (~6.5 km from proposed cross harbour tunnel), Tung Lung Chau (~ 10 km from proposed cross harbour tunnel), and Tai Tam (750 m from proposed Shek O Casting Basin).

Physical Environment

Water Quality

5.23 The proposed Shatin to Central Link Hung Hom to Admiralty Section (SCL (HUH-ADM)) is an extension of the existing East Rail Line from Hung Hom to Admiralty crossing Victoria Harbour. Under the WPCO, Victoria Harbour is within the gazetted Victoria Harbour WCZ. Due to the direct discharge of wastewater after simple screening into the harbour area in the past decades, water quality in the Victoria Harbour was known as poor with high nutrient and sewage bacteria.

5.24 In 2002, after the commissioning of the Stonecutters Island Sewage Treatment Works (SCISTW) under Stage 1 of the Harbour Area Treatment Scheme (hereafter refers to as “HATS Stage 1”), water quality has been significantly improved. However, according to EPD’s water quality monitoring in 2008, a decrease in compliance of water quality objectives was observed in Victoria Harbour compared to 2007 (EPD, 2009). The decrease was mainly due to an increase of total inorganic nitrogen (TIN) levels. Nevertheless, most of the non-compliance only marginally exceeded the objectives. Water quality improvement had been observed in eastern Victoria Harbour and the Eastern Buffer (ibid). On the other hand, due to the effluent from the SCISTW, the E. coli levels in the western harbour and the Western Buffer WCZ have been elevated (ibid). But the E. coli levels have been decreased recently from its peak in 2006.

5.25 Generally, Tai Tam Bay, being remote from dense human population, has the best water quality among all regions within the assessment area. High dissolved oxygen level and low levels of suspended solids, total nitrogen, phosphorus, E. coli and faecal coliforms were observed. Within the Victoria Harbour, the eastern Victoria Harbour and the Eastern Buffer WCZ had a better water quality than the western Victoria Harbour and the Western Buffer WCZ. The water quality of the mid Victoria Harbour where the proposed cross harbour tunnel located was in between the two. Highlight water quality statistics for the assessment area in 2008 are summarized in Table 5.2 below.

Table 5.2 Summary of Highlight Water Quality Statistics for the Assessment Area in 2008⁽¹⁾

Water Quality Parameters	Mid Victoria Harbour	Eastern Victoria Harbour	Western Victoria Harbour	Eastern Buffer WCZ	Western Buffer WCZ	Tai Tam Bay
Dissolved Oxygen (mg/L)	5.0 – 5.3	5.4 - 5.5	5.2 – 5.8	5.8 – 6.2	5.7 – 6.1	6.6
Suspended Solids (mg/L)	5.0 – 5.3	3.9 – 6.2	4.6 – 10.2	4.2 – 4.6	4.8 – 6.4	4.2
Total Nitrogen (mg/L)	0.52 – 0.62	0.38 – 0.48	0.53 – 0.63	0.25 – 0.30	0.34 – 0.49	0.33
Total Phosphorus (mg/L)	0.04 – 0.05	0.03 – 0.04	0.04 – 0.05	0.02 – 0.03	0.03 – 0.04	0.03
E. coli (cfu/100mL)	2,900 – 4,500	330 – 1,100	580 – 5,100	4 – 110	110 – 2,700	2
Faecal Coliforms (cfu/100mL)	6,300 – 11,000	750 – 2,500	1,500 – 13,000	10 – 260	240 – 6,000	4

Note:

(1) EPD, 2009.

5.26 After the commissioning of HATS Stage 1, a substantial improvement in the water quality of the typhoon shelters around Victoria Harbour has been observed (EPD, 2009). Dissolved oxygen (DO) in Kwun Tong Typhoon Shelter (KTTS) increased from the hypoxic levels (1.6 mg/L) in 1998 to 4.6 mg/L in 2008. E. coli level decreased from 100,000 to 2,300 cfu/100mL. Marked reduction in pollutants was also recorded from Yau Ma Tei Typhoon Shelter and Causeway Bay Typhoon Shelter (CBTS). But in general, typhoon shelters in Victoria Harbour had poor water quality.

Sediment

5.27 The seabed in Victoria Harbour was mainly composed of soft bottom sediment with coarse particle size. The marine sediment in central Victoria Harbour (VS5), according to EPD sediment monitoring results, was anaerobic (electrochemical potential -409 mV to -244 mV). The sediment was toxic with a high level of total sulphide (390 mg/kg). The sediment is classified as Category H, as defined in the ETWB Technical Circular (Works) No. 34/2002, as it is also highly contaminated with copper (120 – 220 mg/kg), silver (3.6 – 9.4 mg/kg) and zinc (190 – 340 mg/kg) which exceed the Upper Chemical Exceedance Level (UCEL) (EPD, 2009).

5.28 Victoria Harbour and Tsuen Wan Bay were reported to have high heavy metals levels, particularly copper and silver (EPD, 2009). Due to the discharge of industries as well as contamination from the waste incinerator in Kennedy Town in the past, the level of organic pollutants (e.g. polychlorinated biphenyls (PCBs)) was high in the western harbour.

5.29 Sediment within the typhoon shelters in Victoria Harbour was seriously contaminated. According to EPD’s sediment monitoring results, sediment in the typhoon shelters in Victoria Harbour were often contaminated by various types of heavy metals due to historical discharges from industries (EPD, 2009). The sediment in KTTS contained the highest levels of heavy metals and total PCBs between year 2004 and 2008.

Ecological Baseline Condition

5.30 Marine habitats/resources within the assessment area included subtidal soft bottom habitat, subtidal hard bottom habitat, intertidal habitats (i.e. artificial seawall, rocky shore, and sandy shore), and marine waters/coastal waters habitat (Figure Nos. NEX2213/C/331/ENS/M51/031 and NEX2213/C/331/ENS/M51/032). The existing baseline conditions of the identified habitats/resources within the assessment area are described below.

Subtidal Soft Bottom Habitat

Victoria Harbour, Western Buffer and Eastern Buffer WCZs

5.31 A comprehensive survey on composition of benthos communities of the subtidal soft bottom habitat in the territory was undertaken in 2001 (AFCD, 2002). A total of 12 sampling stations (Stations 52, 53 and 54 in Victoria Harbour WCZ, Stations 17, 43, 46, 48, 49, 50 and 51 in Western Buffer WCZ, as well as Stations 75 and 80 in Eastern Buffer WCZ) were located within the assessment area of this Project. Benthos communities at the sampling stations within Victoria Harbour WCZ and Western Buffer WCZ recorded low or moderate value of species richness (d = <5 / 5-10) and species diversity (H’ = <2 / 2-3). On the other hand, sampling stations within Eastern Buffer WCZ supported moderate or high species richness (d = 5-10 / >10) and species diversity (H’ = 2-3 / >3) of benthos communities. Species evenness was high (J > 0.8) at Stations 46 and 48 in Western Buffer WCZ in both dry and wet seasons.

5.32 The report also summarized the typical benthos species for the different regions in Hong Kong in terms of their abundance (AFCD, 2002). Benthic communities in Victoria Harbour was represented by polychaetes (Cirratulus sp., Schistomeringos rudolphi, Dodecaceria sp. and Naineris sp.), and bivalve (Ruditapes philippinarum) in summer; and by polychaetes (Spionidae sp., Schistomeringos rudolphi, Spiophanes sp. and Sigambra hanaokai), and amphipod (Cheiriphotis megacheles) in winter. Station 52 near Stonecutters Island in Victoria Harbour WCZ supported a distinct benthic assemblage. The benthic communities at this station was dominated by polychaete (Sigambra hanaokai) in summer and comprised of polychaetes (Chaetozone sp., Glycinde gurjanovae, Lepidonotus sp., Nephtys polybranchia, Sigambra hanaokai, Spionidae sp. and Tharyx sp.), coelenterate (Anthopleura sp.), crab (Charybdis variegate), amphipod (Cheiriphotis megacheles, Corophium mortoni and Gammaropsis sp.) and bivalves (Septifer sp. and Theora lata) in winter. Like most part of Hong Kong, benthic assemblages in the Western Buffer WCZ and the Eastern Buffer WCZ were characterized by polychaetes (Aglaophamus dibranchis, Mediomastus sp., Sigambra hanaokai, Cossurella dimorpha and Sigambra sp.), brittle star (Amphipodia obtecta), shrimp (Callianassa japonica), crab (Neoxenophthalmus obscurus) and sipunculan (Apionsoma trichocephalus) in summer; and by polychaetes (Mediomastus sp., Aglaophamus dibranchis, Sigambra hanaokai, Prionospio malmgreni and Prionospio ehlersi), brittle star (Amphipodia obtecta), and crab (Neoxenophthalmus obscurus) in winter.

5.33 In the wet season survey, amphioxus (Branchiostoma belcheri), the cephalochordate of high conservation value, was recorded at sampling station 80 in Eastern Buffer WCZ (AFCD, 2002), which was about 9 km away from the proposed dredging works in Victoria Harbour.

5.34 Amphioxus is considered as rare animal because it inhabits a few scattered locations with high density of occurrence (Poss and Boschung, 1996). Although it can be found globally in shallow, subtidal sand flats in tropical, subtropical and temperate regions (Chen, 2007), amphioxus is listed as Category II protected species in China (Yang et al., 1993). An Amphioxus Reserve Area has been established in Xiamen Bay due to its significant population decline (Yang et al., 1993). In Hong Kong, distribution of amphioxus is confined in eastern water close to Sai Kung (AFCD, 2002) while significant populations have been recorded in Tai Long Wan and Pak Lap Wan with a density of 138-460 ind. /m² (Chen, 2007). Smaller populations with density less than 100 ind./m² have been recorded in Nam She Wan, Long Ke Wan, Tung Lung Chau, Hoi Ha Wan, and waters between Basalt Island and Ninepin Group (CPSL, 2002; Chen, 2007).

5.35 There have been numerous studies on benthic community assemblage conducted within the Victoria Harbour, indicating that the Harbour was generally of low habitat quality with low species diversity and species abundance recorded in the past years (EPD, 2000):

Ÿ Central District, KTTS and Kai Tak Approach Channel - No macroinvertebrate community was found at the seabed (TDD, 2001a, 2001b).

Ÿ Kowloon Bay and KTTS - A total of 54 species was reported (CEDD, 2007). The specimen was dominated by polychaete (61%) and crustacean (36%). Eunice indica was the most abundant species, followed by Mediomastus sp., Cirriformia sp., Glycinde gurjanovae, Glycera chirori and other species. All the species recorded are common and widespread in Hong Kong waters. The species diversity was low (H’ = 1.05-2.31) and evenness was moderate (J = 0.55-0.89).

Ÿ North Point - The community was dominated by common polychaetes and mollusks, with Ruditapes sp. as the most dominant species (EPD, 2004). This species is a commercial species though the conservation importance is not high. The community structure in the North Point area was proved to be relatively stable over time as Ruditapes sp. was recorded as dominant species in previous relevant studies.

Ÿ To Kwa Wan Typhoon Shelter - Only two species of benthic fauna were found, including the dominant polychaete (Capitella capitata) (constituted over 99% of the collected individual number) and a juvenile ocypodid crab (Macrophthalmus sp.) (TDD, 2001a, 2001b). The species diversity and evenness were very low (H’ = 0.049; J = 0.049) (ibid).

Ÿ Stonecutters Island - The benthos community was of low abundance, biomass and biodiversity (EPD, 2004). The community was dominated by common small polychaetes and anthozoans, but over dominated by one anthozoan, Pteroeides sp., which is found in other soft benthic environments (ibid). The ecological value is considered to be very low.

5.36 In Western Buffer WCZ, the benthic community varied in abundance, biomass and biodiversity across the WCZ (EPD, 2004).

Ÿ Kap Shui Mun - The bottom sediment was dominated by polychaetes (83.3%) (CED, 1992; EPD, 1998). Notomastus latericeus was the most abundant among all species while Paraprionospio pinnata was also commonly found. The highly primitive hemichordate Balanoglossus sp., a typical species in muddy habitat, was also recorded from almost all of the sampling stations.

Ÿ Sandy Bay – The benthic community was characterized by high abundance, biomass and biodiversity (EPD, 2004). The number was evenly represented by common polychaetes, crustaceans and echinoderms, but the biomass was over dominated by echinoderms. Species found were of very little conservation importance. Large variation in community structure was reported among stations in this area.

Ÿ East Lamma Channel - The benthos community was characterized by low abundance and biodiversity, as well as very low biomass (EPD, 2004). Small polychaetes and mollusks were the dominant species. Most of these species were small in size with very little conservation importance.

5.37 The benthic community structure at Tathong Channel in Eastern Buffer WCZ was relatively stable (EPD, 2004). Similar to previous studies, it was characterized by high abundance and biodiversity but low biomass. However, the community was dominated by small opportunistic species of polychaetes with very low conservation importance.

5.38 Surveys on the subtidal soft bottom benthic communities were conducted along the proposed cross harbour section of this Project and its vicinity in February and May 2009 as well as in CBTS in August and November 2009. The sampling locations are shown in Figure No. NEX2213/C/331/ENS/M51/003. Sampling stations VHR-B1, VHR-B2 and VHR-B3 were located along the proposed alignment, and VHR-B4 and VHR-B5 were in the vicinity of the alignment. Whilst, CBTS-B1 and CBTS-B2 were situated within the southeast corner of CBTS.

5.39 The sediment at VHR-B1 consisted of about 20% silt-clay fraction (particle diameter of <64μm) and 80% coarse materials (particle diameter of >2000μm) including gravels, coarse sand and broken shells of mollusks and crustaceans. The sediment at other sampling stations was relatively muddy. VHR-B2 composed of about 70% silt-clay fraction and 30% coarse materials, and VHR-B3, VHR-B4, VHR-B5, CBTS-B1 and CBTS-B2 consisted of about 85% silt-clay fraction plus 15% coarse materials. The sediment within CBTS (VHR-B3, CBTS-B1 and CBTS-B2) was dark black in color and released a pungent smell of hydrogen sulphide.

5.40 Along the proposed alignment crossing the harbour, a total of 1,359 and 919 individuals of 77 taxa were recorded from the 15 samples collected in dry and wet seasons respectively. No fauna was collected within CBTS during dry season and only 53 individuals of 1 species were found in wet season. The most diverse phylum was polychaetes (52 species). Others included crustaceans (10 species), mollusks (7 species), fishes (3 species), echiuran (1 species) and cnidarian (1 species). Although a relatively high abundance was recorded, the benthic community was dominated by polychaetes, which comprised 70 to 80% of the specimens collected. Mean biomass was small, ranging from 46 to 108 g/m², in which 72% to 95% were contributed by mollusks. Similar abundance but different biomass was obtained between dry and wet season. Details of the benthos survey are presented in Appendix 5.1.

5.41 Higher species diversity (H’ = 2.4) was also obtained near Hung Hom area and high species evenness (J = 0.8) at VHR-B1 and VHR-B4. On the contrary, low species richness, abundance, diversity and evenness were observed near or within CBTS.

5.42 The mean species diversity (H’= 1.7 to 2.4) and evenness (J= 0.6 to 0.8) along the proposed alignment of cross harbour tunnel were similar to the previous survey conducted from 2004 to 2006 where the H’ and J of benthic community at the middle of Victoria Harbour near Causeway Bay were 1.7+/-0.59 and 0.73+/-0.16 respectively (Shin et al., 2008). No rare species or species of conservation interest were recorded. The values were low compared to those in unpolluted water zones such as Eastern and Southern waters (mean H’ =2.82 and J=0.81) (Shin et al., 2004).

Tai Tam Bay (Shek O)

5.43 One sampling station (Station 62) under the aforesaid benthic survey (AFCD, 2002) was close to the proposed IMT casting basin. The results showed that the subtidal soft bottom habitat supported a medium species diversity (42 - 45 species recorded; H’= 3.29 to 3.36) and abundance (248 – 286 individuals). The benthic composition is typical of Hong Kong waters. No rare species or species of note were recorded.

5.44 Ong Che and Morton (1991) found that the sediments within Tai Tam Bay containing over 90% silt-clay. Polychaete such as Aglaophamus toloensis, Nephtys polybranchia, Lanice conchilega, Sternaspis scutata and several species of spionid were typical in the area. Other representative species were the bivalves Theora lata, Merica sp. and Veremolpa scabra; the echinoderms Protankyra bidentata, Acaudina molpadioides, Schizaster lacunosus and Lovenia elongata. Juveniles of many species were recorded, indicating the site as an unstressed environment supporting normal breeding. However, Sigambra tentaculata was also present, indicating moderate pollution.

5.45 Trawl survey by CES (1994) in 1993 revealed the offshore area in Tai Tam Bay supported a moderate to high diversity of pelagic and demersal species (H’ 2.84 – 4.13, J 0.66 – 0.75). There were a total of 96 species recorded. Numbers of individuals varied from 64 to 671 in each trawl. Fish constituted the majority of specimen besides a single species of shrimp. Two rare crab species (Parthenope platylambrus validus and Calappa philargius) and one crab species of particular biological interest (Dorippe sp.) were recorded.

5.46 Benthic surveys were conducted at the vicinity of the proposed IMT casting basin within Tai Tam Bay. The sampling locations are shown in Figure No. NEX2213/C/331/ENS/M51/011.

5.47 The sediment collected at SKO-B1 and SKO-B2 were grey, fine mud, consisted of about 90% silt-clay fraction and 10% coarse material. Whilst, the sediment at SKO-B3 and SKO-B4 were brown, fine sand, consisted of about 75% fine sand fraction (particle diameter 125 – 500 μm) and 25% coarse materials.

5.48 The surveys recorded 590 and 251 specimens of 85 taxa from 12 samples during the wet and dry seasons respectively. The most diverse phylum was polychaetes (46 species). Others included crustaceans (16 species), mollusks (8 species), echinoderms (7 species), fish (2 species), sipunculan (2 species), echiura (1 species) and amphioxus (1 species). The abundance was moderate with a mean number of 491.5 ind/m² in wet season and 209.5 ind/m² in dry season. But the mean biomass was low, ranged from 5.6 to 7.8 g/m², in which over 70% of total biomass were dominated by crustacean. Medium species diversity (H’ = 2.13 – 3.11) and high species evenness (J = 0.76 – 0.95) were obtained across the region. Among the sampling points, SKO-B1 and SKO-B2 supported the relatively low diversity (11 - 17 species recorded) and species richness (70 - 97 ind/m² and 0.3 – 2.2 g/m²). Details of the benthos surveys are presented in Appendix 5.1.

5.49 Amphioxus Branchiostoma belcheri was found at SKO-B2 (3 ind/m²), SKO-B3 (140 ind/m²) and SKO-B4 (70 ind/m²) during wet season but only found at SKO-B4 (7 ind/m²) in dry season (Figure No. NEX2213/C/331/ENS/M51/011). No amphioxus was found at SKO-B1, the closest sampling point to the proposed work areas. All the amphioxus individuals recorded were less than 1 year old with body length ranged from 4 – 15 mm. Its densities at SKO-B3 and SKO-B4 were moderate compared to other places of occurrence (~50-460 ind/m² on average) in Hong Kong waters. The occurrence of small juveniles in the wet season is possibly due to random settlement via the planktonic larval stage of B. belcheri. It is understood that amphioxus reproduces in the wet season, higher levels of larval recruitment would thus be expected. Very low occurrence in the dry season suggests that the conditions of Shek O Quarry might not be suitable for continual survival of amphioxus after settlement. B. belcheri in Hong Kong prefers water depth between 5 and 23 m and clear oceanic water combined with sand sediment of low organic content are the most important habitat requirements for amphioxus (Chen, 2007). The surveys found that the seabed in the vicinity of the Shek O Quarry was silty in nature which is not a preferred habitat for amphioxus.

Subtidal Hard Bottom Habitat

Victoria Harbour, Western Buffer and Eastern Buffer WCZs

5.50 In Hong Kong, the subtidal hard bottom habitat in the eastern water supports the richest coral communities. The water in this region is free from the influence of estuarine water from the Pearl River. As water in Victoria Harbour was turbid with high level of suspended solids, it was not suitable for the survival and colonization of most coral.

5.51 Many dive surveys have been conducted within Victoria Harbour, Western Buffer and Eastern Buffer WCZs, including central Victoria Harbour (EPD, 2004; CEDD, 2007b; HKCGCL, 2010), To Kwa Wan (HKCGCL, 2010), Kai Tak (CEDD, 2007a), Green Island and Small Green Island (TDD, 1997). The findings are summarized below:

Ÿ Central Victoria Harbour - Low coverage (<1%) of a single species of hard coral (Oulastrea crispata) was recorded in the ex-Public Cargo Working Area and one species of gorgonian (Echinomuricea sp.) and two small colonies of Oulastrea crispata on the seawall at North Point (~1 km from the proposed cross harbour tunnel) (CEDD, 2007b; HKCGCL, 2010). All colonies found were small in size (3-8 cm in diameter) with fair health condition. The coastline at North Point was found to be modified heavily due to extensive urban development (EPD, 2004).

Ÿ To Kwa Wan – Low coverage (<1%) of one single species of hard coral (Oulastrea crispata), one colony of gorgonian Euplexaura sp. and two colonies of soft coral Dentronephthya gigantean were recorded. The hard coral colonies were generally in good condition with size ranging from less than 1 cm² to over 150 cm² (HKCGCL, 2010).

Ÿ Kai Tak - Sparse coverage (1-5%) of single hard coral species (Oulastrea crispata) (CEDD, 2007a). All colonies recorded were in fair health condition and the sizes ranged from less than 1 cm to 30 cm in diameter. Most of the colonies found were small in size (~3 cm to 8 cm) and were covered by layer of sediment.

Ÿ Green Island and Small Green Island - Four species of soft coral were reported at Green Island and Small Green Island (TDD, 1997). White Sea Whip (Euplexaura curvata) was the most frequently encountered species in Green Island, followed by Pink Soft Coral (Dendronephthya sp.). Other species recorded included Orange Sea Fan (Echinogorgia complexa) and Purple Sea Whip (Ellisella grandis). The species recorded are not rare to Hong Kong.

5.52 Further west or east of Victoria Harbour, in Western Buffer and Eastern Buffer WCZs, were found to support higher coverage and diversity of hard and soft coral community:

Ÿ South Tsing Yi - Five colonies of gorgonians (Junceella juncea and Gorgonacea sp.) were found at the waters at south Tsing Yi in trawl survey (CED, 1995).

Ÿ Sandy Bay/West Lamma area - Fourteen hard coral and five soft coral taxa were recorded in Sandy Bay / West Lamma area (EPD, 2004). Soft coral (Echinomuricea sp.) and the bryozoans (Schizoporella errata) were the most ubiquitous taxa. Low soft coral coverage (<5%) was found in Sandy Bay with only small isolated Echinomuricea colonies. Nine species of hard corals with less than 5% coverage were also recorded. Psammocora superficialis and Porites lobata were the most abundant and the Faviids were also well represented. Coral communities found are common species. The overall ecological values for the soft and hard corals are medium and low respectively.

Ÿ East Lamma Channel - A total of 19 hard coral and 8 soft coral taxa were recorded at this area (EPD, 2004). The most common species were hard coral (Cyphastrea spp.), soft coral (Echinomuricea spp.) and sponges (ibid). Soft corals (Dendronephthya), sea whips (Junceella) and sea fans (Melithaea) were found at Ap Lei Pai, Ap Lei Chau and Telegraph Bay (CED, 1995). Two genera of soft coral and fourteen hard coral species with less than 5% coverage were found at Ap Lei Chau (EPD, 2004). Echinomuricea, Dendronephthya spp. and Faviids were the most abundant. Low coverage of Oulastrea crispata was identified at the seawall off Aberdeen Preliminary Treatment Works (PTW) (EPD, 2008). The sizes of these colonies were small (approximately 3 – 5 cm). The bottom of this area was composed of thick mud with very little hard substrate and was considered of low ecological value.

Ÿ East Hong Kong - Significant soft coral coverage (10 – 50%) and seven hard coral species (less than 5% coverage) was found in this area (EPD, 2004). Echinomuricea spp. and Goniopora stutchburyi were the most abundant soft and hard coral found.

Ÿ Tung Lung Chau - Good hard coral communities of high conservation importance were found around Tung Lung Chau with ten hard coral taxa (Acropora, Cyphastrea, Montipora, Hydnophora, Acanthastrea, Porites, Goniopora, Favia, Pavona and Plesiastrea) recorded (CED, 1995). A total of 21 hard coral and 8 soft coral taxa were recorded in Tung Lung Chau / Junk Bay area, with Cyphastrea spp. and Echinomuricea spp. as the most ubiquitous taxa (EPD, 2004). In south Tung Lung Chau, four soft coral genera and four hard coral species with less than 5% coverage were reported, and Echinomuricea was the most abundant (ibid). Whilst, 10 – 25% coverage of seven hard coral species and Echinomuricea spp. present in low number (less than 5% coverage) was recorded in North Tung Lung Chau, with Favites being the dominant species (ibid). However, the bottom of this area was composed of thick mud with very little hard substrate and was considered of low ecological value.

Ÿ Tathong Channel - Rich coral communities occurred at East Joss House Bay, North Tung Lung Chau and Ngan Wan (Oceanway, 2003). At East Joss House Bay, there was 10 – 25% coverage of hard corals confined to shallow areas with a total of 23 species coral recorded. Platygyra acuta was the dominant species at this site. In contrast, there was relatively little soft / gorgonian coral at this location (less than 5% coverage). Similar hard coral coverage (10 – 25%) was found in the shallow waters off North Tung Lung Chau and fewer hard coral species (7 species) were recorded. Favites were the dominant species. Soft and gorgonian corals were scattered and sparse (less than 5%) in deeper waters. At Ngan Wan, rich and diverse soft / gorgonian coral community dominated by Echinomuricea sp. extended from the shallow to deeper water. In addition, seven hard coral species occurred in the shallows but with sparse cover. Goniopora stutchburyi was the most frequently occurring hard coral at this location. Other areas surveyed such as West Joss House Bay and South Tung Lung had comparatively low coral abundance and diversity.

5.53 In order to provide sufficient and updated relevant baseline information on marine ecology in the vicinity of the Project area, dive surveys included spot-check reconnaissance dives and Rapid Ecological Assessment were carried out at Hung Hom seafront in February, March and May 2009 and within CBTS in August 2009. Two hard species of less than 1% coverage was recorded within the works areas at the seafront off Hung Hom and its vicinity (Figure No. NEX2213/C/331/ENS/M51/004). The two hard species were Oulastrea crispata and Balanophyllia sp. Both species are common and widespread in Hong Kong. Most of the colonies found were in small size (1 to 5 cm) and in fair health condition. No coral was observed within CBTS. The ecological value of subtidal hard bottom habitat in the proposed works areas in Victoria Harbour and its vicinity is low. Details of the coral surveys are presented in Appendix 5.2.

5.54 Oulastrea crispata is known to be stress tolerant with a wide range of adaptations to different environmental conditions including those unfavourable to most corals as well as geographic locations (Chen et al., 2003). With an opportunistic life history trait, a wide range of reproductive strategies and surface-orientation independent growth, O. crispata is able to colonize a wide range of substrata and to flourish as a pioneer colonizer of newly immersed structures (Lam, 2000a & 2000b). The species is common and widespread in Hong Kong marine waters, especially those more turbid and harsh environment in the western waters (Chan et al., 2005). Balanophyllia sp. is also a common coral in Hong Kong waters. The colonies of Balanophyllia sp. are cryptic, they are unlikely to be noticed unless sought, but they occur in deep waters of Hong Kong, even the turbid and harsh north-western waters (Scott, 1984).

Tai Tam Bay (Shek O)

5.55 AFCD (2004) recorded moderately high coverage and moderate level of species richness of hard corals at the southeast coast of Tai Tam Bay (~750 m away from the proposed IMT casting basin). Twenty-two species were recorded with 1 to 10% coverage, characterized by faviid Cyphastrea microphthalma. However, a high level of dead coral and coral injury was indicated.

5.56 Under the present study, 11 hard coral species of low coverage (less than 1%) were found along the coast of the Shek O Quarry (Figure No. NEX2213/C/331/ENS/M51/011). Oulastrea crispata was the dominant species. Other hard coral recorded included Montipora peltiformis, Goniopora stutchburyi, Cyphastrea serailia, Porites lutea, Psammocora superficialis, Favia speciosa, Favites pentagona, Acropora solitaryensis, Tubastrea sp., and Pavona decussata. Most of the species are common and widespread in Hong Kong, except Acropora solitaryensis which is locally uncommon. The corals were small in size (2 – 25 cm) but in good condition. Details of the coral surveys are presented in Appendix 5.2.

Intertidal Habitat – Artificial Seawall

Victoria Harbour, Western Buffer and Eastern Buffer WCZs

5.57 Artificial seawall was the most common type of intertidal habitat in the Victoria Harbour WCZ. Intertidal habitats within the assessment area mostly comprised of the artificial vertical seawalls, with a small portion of man-made sloping seawall and rockfill at the Wan Chai Ferry Pier and around the Hong Kong Convention and Exhibition Centre (HKCEC).

5.58 Artificial seawalls and concrete embanked wharf piles at To Kwa Wan and North Point were studied by HKCGCL (2010). Twenty-two intertidal species were recorded. The littoral fringe was dominated by Echinolittorina spp., followed by barnacle (Balanus amphitrite), limpet (Cellana grata) and rock oyster (Saccostrea cucullata) at the upper eulittoral zone. Whilst Haliplanella luciae and Ascidiaea (Atyela plicata) were recorded at lower eulittoral and upper sub-littoral zones. All of the recorded species are locally common.

5.59 Intertidal fauna survey was undertaken by CEDD, 2007b on the artificial seawalls and rockfills around HKCEC, CBTS, and the seafront off City Garden in North Point. The artificial seawalls were inhabited densely by a few species of sessile encrusting fauna, including chiton (Acanthopleura japonica), barnacle (Tetraclita squamosa), and bivalve (Saccostrea cucullata). The mobile fauna recorded on the artificial seawall were the common sea slater (Ligia exotica) and topshell (Monodonta labio). Encrusting algae (Pseudulvella applanata and Hildenbrandia sp.) were also recorded on the surface of the artificial seawalls but no erect algae or higher flowering plant was found during the surveys. All the recorded intertidal fauna and flora are locally common.

5.60 Another intertidal survey was conducted by CEDD (2007a) at KTAC and the former airport runway along the coast of Kowloon Bay. Only brown algae Hincksia mitchelliae was recorded at KTAC, revealing the poor habitat quality at the area. Whilst, artificial seawalls along the runway were inhabited densely by several species of sessile encrusting fauna, including bivalve (Saccostrea cucullata) and barnacle (Balanus amphitrite, Tetraclita japonica and T. squamosa); and the mobile species, such as periwinkle (Echinolittorina radiata), topshell (Monodonta labio), limpet (Cellana grata, C. toreuma and Patelloida saccharina), sea slater (Ligia exotica) and crab. Encrusting algae (Pseudulvella applanata and Hildenbrandia sp.) were also recorded on the surface of the artificial seawalls.

5.61 EPD (2004) carried out intertidal surveys at Sandy Bay and Tung Lung Chau. Fifteen invertebrate species were found at Sandy Bay. Grazing snail (Echinolittorina trochoides) was the most dominant species and represented about 22% of total individuals found in the intertidal zones. Other abundant invertebrates included grazing snail (E. trochoides and Monodonta labio), limpet (Siphonaria sirius) and chiton (Acanthopleura japonica). Whilst, 15 species were recorded at Tung Lung Chau. Similarly, grazing snail (E. trochoides and Echinolittorina vidua) was the most dominant species and made up of over 50% of total individuals found in the intertidal zones. Other abundant species included limpet (Cellana grata and Cellana toreuma). Most of the species recorded were common and widespread in Hong Kong intertidal habitat and no rare species were present. The ecological value at these sites was low.

5.62 Eight intertidal species were recorded at the seawall off the Aberdeen Preliminary Treatment Works by EPD (2008). Capitulum mitella and Tetraclita squamosa were the dominant species. Other species found included limpet (Cellana grata), topshell (Monodonta labio), chiton (Acanthopleura japonica), false limpet (Siphonaria laciniosa), dog whelk (Thais clavigera), and sea slater (Ligia exotica). All species recorded are common and widespread in Hong Kong.

5.63 HyD (2001) showed assemblages on the artificial seawall between Siu Lam and area near Ka Loon Tsuen was typical of moderately exposed rocky shore communities in Hong Kong. The upper and lower tidal level of the artificial seawall were dominated by Littoraria articulata and Monodonta spp. respectively. Echinolittorina radiata, Cellana toreuma, Notoacmea spp., Nerita albicilla and Thais spp. were also recorded. Species diversity of this man-made seawall habitat was low.

5.64 The surveys on intertidal communities conducted under this EIA investigated the Hung Hom area (Figure No. NEX2213/C/331/ENS/M51/003) in February, March and May 2009 and CBTS in August and November 2009. The number of intertidal species recorded varied largely from 2 to 22 species among survey locations and the abundance of the recorded species was low in general. No rare species was recorded. Species diversity was low within CBTS. At the Hung Hom seafront, the lower shore was dominated by rock oyster (Saccostrea cucullata) and barnacle (Tetraclita squamosa and T. japonica). Corallina encrusting algae, Hildenbrandia rubra, and Porphyra suborbiculata were found covering the lower shore. Whilst, periwinkle (Littoraria articulata, Echinolittorina trochoides and E. radiata) and sea slaters (Ligia exotica) were commonly found at the upper shore. Other organisms recorded included black mussel (Septifer virgatus), anemone (Spheractis cheungae), chiton (Acanthopleura japonica), limpets (Cellana grata, C. toreuma, Patelloida saccharina and P. Pygmaea), false limpet (Siphonaria japonica), and whelk (Thais clavigera). The mid shore was dominated by Balanus amphitrite.

5.65 Within CBTS, the lower shore was dominated by rock oyster (Saccostrea cucullata) and barnacle (Balanus amphitrite). Periwinkles (Echinolittorina trochoides, E. radiata and Littoraria articulata) were abundant on the high shore. Other recorded species included sea slater (Ligia exotica) and limpet (Cellana grata and Patelloida saccharina).

5.66 The survey area covered under this EIA showed little seasonality in intertidal assemblages. Similar diversity and abundance between dry and wet seasons were recorded. Ulva sp. was only found in dry season, whereas Hildenbrandia rubra, Ligia exotica, Hemigrapsus sanguineus, and Echinolittorina trochoides were found in wet season. Detailed results of the intertidal survey in dry and wet seasons are presented in Appendix 5.3.

Tai Tam Bay (Shek O)

5.67 Artificial sloping seawall armoured with boulders was found along the shore close to where the proposed IMT casting basin would be situated (Figure No. NEX2213/C/331/ENS/M51/011). The number of species ranged from 14 to 20. No rare species was recorded. The lower shore was dominated by periwinkles (Echinolittorina trochoides and E. radiata), and covered by encrusting algae (Kyrtuthrix maculans and Hildenbrandia rubra). Barnacle (Tetraclita squamosa) and black mussel (Septifer virgatus) were common at the high shore. Other fauna observed included rock oyster (Saccostrea cucullata), barnacles (Capitulum mitella and Tetraclita japonica), sea slater (Ligia exotica), chiton (Acanthopleura japonica), limpet (Cellana grata, C. toreuma, Patelloida saccharina and P. Pygmaea), periwinkle (Littoraria articulata and E. vidua) and topshell (Monodonta labio). The overall abundance was low. Detailed intertidal survey results are presented in Appendix 5.3.

Intertidal Habitat - Natural Rocky Shore

Victoria Harbour, Western Buffer and Eastern Buffer WCZs

5.68 No natural rocky shore habitat was recorded within the proposed marine-based works areas. Natural rocky shore habitat found in the vicinity was along the Kellet Island. Far away from the proposed marine-based works areas, natural rocky shore is found fringing the east coast of Hong Kong Island, Hoi Sham Park at To Kwa Wan, from Joss House Bay around the coast to Clear Water Bay, Ka Loon Tsuen, Tsing Lung Tau, and Tung Lung Chau.

5.69 The natural rocky shore of the Kellet Island was surveyed in August 2000 under TDD (2001a). The field survey indicated that the species assemblages were typical of sheltered rocky shore communities with high quantities of top shells (Monodonta australis) dominating the lower shore and periwinkles (Echinolittorina millegrana) dominating the upper shore. Other intertidal species including stalked barnacle (Capitulum mitella), acorn barnacle (Tetraclita squamosa), common chiton (Liolophura japonica), and limpet (Cellana toreuma) were occasionally observed. No rare species or species of conservation value were noted during the survey.

5.70 A small natural coastline comprised of large boulders, cobbles, bedrocks, and some old concrete debris was found by CEDD (2007b) at the northern Kellet Island. The area was subject to high level of disturbance due to construction and reclamation works in the past. Seven fauna species were recorded dominated by periwinkles (Echinolittorina millegrana) at the upper shore and topshell (Monodonta australis) at the lower shore. Other intertidal species found included limpet (Cellana toreuma), nerite (Nerita chamaeleon), stalked barnacle (Capitulum mitella) and acorn barnacle (Tetraclita squamosa). All these species were commonly found in most of the shorelines in Hong Kong and no species of conservation importance was reported.

5.71 At the rocky shore of Hoi Sham Park, only 11 intertidal species were recorded (HKCGCL, 2010). Periwinkles (Echinolittorina spp.) were common at the splashed zone. Whilst, the eulittoral zone was dominated by Balanus amphitrite and Saccostrea cucullata. All species recorded are common in Hong Kong.

5.72 The lower shore of the natural boulder coastline at Ka Loon Tsuen was also dominated by periwinkles (Echinolittorina radiata) (HyD, 2001). Other intertidal species included common whelk (Thais spp.), limpet (Cellana toreuma), smooth limpet (Notoacmea spp.), false limpet (Siphonaria spp.), and barnacle (Tetraclita japonica) in the natural boulder coastline.

5.73 HyD (1999) identified the natural boulder coastline at Tsing Lung Tau typical of exposed rocky shore assemblages in Hong Kong, with abundant barnacles (Capitulum mitella and Tetraclita squamosa), chiton (Acanthopleura japonica), limpets (Cellana toreuma and Patelloida saccharina) and periwinkles (Echinolittorina radiata and E. trochoides). Other intertidal species included bivalves and sea anemones were present in low quantities. Encrusting algae was also present and dominant in the wet season.

Tai Tam Bay (Shek O)

5.74 A total of 30 species were recorded at the natural rocky shore habitats in the vicinity of Shek O Quarry (CES, 1994). The sheltered and exposed shores exhibited similar species but higher abundance and wider distribution at exposed sites. The high shore was characterized by blue-green algae Kyrtuthrix, barnacles Tetraclita squamosa, grazing gastropods Echinolittorina trochoides and E. vidua, limpets Cellana grata and C. toreuma and isopod Ligia exotica. Stalked barnacle Capitulum mitella and mussel Septifer virgatus were abundant in the crevices and pools. High abundance of chiton Acanthopleura japonica and barnacle T. squamosa were found on the mid shore, with large number of mobile fauna such as dogwhelk Thais clavigera, gastropods Nerita albicilla, Planaxis sulcatus and C. grata etc. The low shore was characterized by large Saccostrea cucullata oysters and the encrusting and coralline algae Hildenbrandia, Ralfsia and Corallina. No rare species were found.

5.75 Natural bedrock was found at the northern coast of Shek O Quarry during the survey conducted under this EIA (Figure No. NEX2213/C/331/ENS/M51/011). 19 to 22 intertidal fauna species were found at the sampling points. Species composition was similar to the artificial intertidal habitats in Shek O Quarry area surveyed under this EIA. Green mussel (Perna viridis) is the only species recorded not found at artificial intertidal habitats, and relatively higher abundance of barnacle (Tetraclita japonica) was observed. Detailed intertidal survey results are presented in Appendix 5.3.

Intertidal Habitat - Sandy Shore

Victoria Harbour, Western Buffer and Eastern Buffer WCZs

5.76 Sandy shore habitat was identified at the southeast corner of CBTS, in Tung Lung Chau and the eastern coast of Hong Kong Island.

5.77 A sandy shore was abutted the proposed mooring area at the southeast corner of CBTS. The access to the shore was restricted during the survey period. Based on site observation, the site was natural but very disturbed with lots of garbage and influenced by the polluted water from the typhoon shelter. No intertidal fauna were observed. It is expected that the sandy shore would only support a very low species diversity and abundance. The location and the condition of the sandy shore is shown in Figure No. NEX2213/C/331/ENS/M51/003 and Appendix 5.4, respectively.

5.78 In the vicinity of the assessment area, sandy shores with higher wave exposure were previously surveyed at the bathing beaches in Big Wave Bay and Shek O by Wong (1990). Dominant species were surf clams Donax semigranosus and D. cuneatus. Other species recorded were mole crab (Hippa pacifica), hermit crabs (Calcinus herbstii), ghost crabs (Ocypode ceratophthalma), sand crabs (Matuta lunata), mysid shrimps (Archaromysis sp.), and the isopod (Excirolana chiltoni).

Tai Tam Bay (Shek O)

5.79 The beach to the south of the Shek O Quarry was surveyed by CES (1994) in 1993. The sand was very coarse and heavily disturbed by wave action. No marine fauna was recorded during the survey.

Marine Waters/Coastal Waters Habitat

5.80 Chinese White Dolphin (Sousa chinensis) and Finless Porpoise (Neophocaena phocaenoides) are the two most commonly found marine mammals in Hong Kong. Most Chinese White Dolphin groups were sighted in Northwest Lantau, Northeast Lantau, West Lantau and Southwest Lantau, and a few sightings were made in Deep Bay and Southeast Lantau (AFCD, 2009, 2010b). Only two areas with consistent dolphin usage were identified, including the waters around Lung Kwu Chau and the stretch of coastline from Shum Wat to Fan Lau (AFCD, 2010b). Finless Porpoise only occurs in the eastern and southern waters of Hong Kong (AFCD, 2009, 2010b). Both species were never recorded in Victoria Harbour and Tai Tam Bay.

Ecological Evaluation

5.81 Based on the ecological baseline information discussed above, the ecological significance of marine ecological habitats identified within the assessment area have been assessed and evaluated in Tables 5.3 to 5.8, in accordance with the EIAO-TM Annex 8 Table 2 criteria.

Table 5.3 Ecological Evaluation of Subtidal Soft Bottom Habitat within the Assessment Area

Criteria	Subtidal Soft Bottom Habitat
	Victoria Harbour	Western Buffer WCZ	Eastern Buffer WCZ	Tai Tam Bay
Naturalness	Habitats have been subjected to high degree of disturbance from urban development and fisheries and are under the influence of water pollutants from Pearl River and local urban discharges.	Habitats have been subjected to high degree of disturbance from urban development and fisheries and are under the influence of water pollutants from Pearl River and local urban discharges.	Habitats have been subjected to anthropogenic disturbance from urban development and are under the influence of water pollutants from local urban discharges.	Habitats have been subjected to some level of disturbance by fisheries vessel trawling.
Size	Habitat is large in extent.	Habitat is large in extent.	Habitat is large in extent.	Habitat is large in extent.
Diversity	Species diversity was generally low (H’: 1.05-2.4). Species diversity in typhoon shelter was extremely low (H’: 0.049).	Species diversity was low to moderate (H’: 1.39 to 3.14).	Species diversity was high (H’: 2.96-3.5).	Species diversity was moderate to high (H’: 2.13 - 3.36).
Rarity	All species recorded are common and widespread in Hong Kong.	All species recorded are common and widespread in Hong Kong.	Amphioxus Branchiostoma belcheri was previously found in Tathong Channel (AFCD, 2002).	Amphioxus Branchiostoma belcheri was found in waters south of Shek O Quarry and the offshore area.
Recreatability	High, benthic organisms may recolonize disturbed seabed area.	High, benthic organisms may recolonize disturbed seabed area.	Moderate, benthic organisms may recolonize disturbed seabed area. Amphioxus Branchiostoma belcheri inhabits in a few scattered locations.	Moderate, benthic organisms may recolonize disturbed seabed area. Amphioxus Branchiostoma belcheri inhabits in a few scattered locations.
Fragmentation	Not fragmented	Not fragmented	Not fragmented	Not fragmented
Ecological linkage	Not functionally linked to any highly valued habitat in close proximity.	Not functionally linked to any highly valued habitat in close proximity.	Functionally linked to highly valued habitat in Tathong Channel where Amphioxus Branchiostoma belcheri was found.	Functionally linked to highly valued habitat in Cape D’aguilar where the Hok Tsui (Cape D’aguilar) SSSI and Cape D’aguilar Marine Reserve located.
Potential value	Low	Low	Moderate	Moderate
Nursery / breeding ground	No significant record	No significant record	No significant record	No significant record, the occurrence Amphioxus Branchiostoma belcheri is possibly due to random settlement via the planktonic larval stage of the species.
Age	N/A	N/A	N/A	N/A
Abundance / Richness of wildlife	Species richness is low (d<10)	Species richness is low (d<10)	Near Victoria Harbour: species richness is low (d<10). Far from Victoria Harbour: species richness is moderate (d = 10-14)	Species richness is low (d<10).
Ecological Value	Low	Low	Low to moderate	Moderate

Table 5.4 Ecological Evaluation of Subtidal Hard Bottom Habitat within the Assessment Area

Criteria	Subtidal Hard Bottom Habitat
	Victoria Harbour WCZ	Western Buffer WCZ	Eastern Buffer WCZ	Tai Tam Bay
Naturalness	Habitats were subject to certain degree of urban development and water pollution from local urban discharges and the Pearl River. Habitats at Green Island were largely natural.	Habitats were subject to certain degree of urban development and water pollution from local urban discharges and the Pearl River.	Habitats were largely natural but subject to some degree of urban development and water pollution from local urban discharges.	Habitats were subject to some level of disturbance by fisheries vessel trawling.
Size	Small to medium. Corals recorded at Hung Hom, Causeway Bay, North Point, To Kwa Wan and Kai Tak.	Small to medium. Corals recorded at South Tsing Yi, Sham Tseng, Tsing Lung Tau, Sandy Bay, Aberdeen Preliminary Treatment Work (PTW), and Ap Lei Chau.	Medium. Corals were restricted to shallow subtidal areas with hard substrate and attained moderate or high coverage at a restricted number of sites such as Joss House Bay, South Ngau Wan, and Tung Lung Chau.	Medium. Corals were restricted to shallow subtidal areas with hard substrate and attained moderate or high coverage at a restricted number of sites such as southeast coast of Tai Tam Bay.
Diversity	Generally low. 2 hard coral, 2 gorgonian and 1 soft coral species recorded within the Harbour area, and 4 soft coral species recorded at Green Island and Small Green Island.	Generally low. Two gorgonian species recorded at south Tsing Yi. Moderate coral diversity found at East Lamma Channel, Sandy Bay, and Ap Lei Chau (14 – 19 hard coral taxa and 5 – 8 soft coral taxa).	Moderate coral diversity at Joss House Bay, Tung Lung Chau, and Ngau Wan (4 -23 hard coral and 4 - 8 soft coral taxa).	Low to moderate around the Shek O Quarry (11 hard coral species). Moderate diversity recorded at Tai Tam Bay in general (22 hard coral species).
Rarity	No rare species were recorded.	No rare species were recorded.	No rare species were recorded.	No rare species were recorded.
Recreatability	Moderate but it may take 5 to 10 years for re-colonization.	Moderate but it may take 5 to 10 years for re-colonization.	Moderate but it may take 5 to 10 years for re-colonization.	Moderate but it may take 5 to 10 years for re-colonization.
Fragmentation	Not fragmented	Not fragmented	Not fragmented	Not fragmented
Ecological linkage	Not structurally and functionally linked to any highly valued habitat in close proximity.	Not structurally and functionally linked to any highly valued habitat in close proximity.	Not structurally and functionally linked to any highly valued habitat in close proximity.	Not structurally and functionally linked to any highly valued habitat in close proximity.
Potential value	Low	Generally low Moderate at the southern portion of Western Buffer WCZ.	Moderate, due to the high coverage and moderate coral diversity at Joss House Bay and Tung Lung Chau.	Low, within the proposed marine-based works area for IMT casting basin. Moderate value at Tai Tam Bay.
Nursery / breeding ground	No significant record	No significant record	No significant record	No significant record
Age	N/A	N/A	N/A	N/A
Abundance / Richness of wildlife	Generally low for abundance and species richness (<5% coverage)	Generally low for abundance and species richness (<5% coverage)	Low at Ngam Wan. Moderate at Joss House Bay and Tung Lung Chau (10 – 25% coverage)	Low around Shek O Quarry (<1% coverage) Low to moderate at the southeast coast of Tai Tam Bay (1-10% coverage)
Ecological Value	Low	Generally low. Low to moderate at southern portion of Western Buffer WCZ	Low to moderate	Low to moderate

Table 5.5 Ecological Evaluation of Artificial Seawall Habitat within the Assessment Area

Criteria	Artificial Seawall Habitat
	Victoria Harbour WCZ	Western Buffer WCZ	Eastern Buffer WCZ	Tai Tam Bay
Naturalness	Low. Man-made habitat	Low. Man-made habitat	Low. Man-made habitat	Low. Man-made habitat
Size	Large	Large	Moderate	Moderate
Diversity	Low in general. Very low at CBTS.	Low	Low	Low
Rarity	No rare species were recorded.	No rare species were recorded.	No rare species were recorded.	No rare species were recorded.
Recreatability	High. Man-made habitat can be readily recreated.	High. Man-made habitat can be readily recreated.	High. Man-made habitat can be readily recreated.	High. Man-made habitat can be readily recreated.
Fragmentation	Not fragmented	Not fragmented	Not fragmented	Slightly fragmented as the area was dominated by natural intertidal habitats.
Ecological linkage	Not structurally and functionally linked to any highly valued habitat in close proximity.	Not structurally and functionally linked to any highly valued habitat in close proximity.	Not structurally and functionally linked to any highly valued habitat in close proximity.	Not structurally and functionally linked to any highly valued habitat in close proximity.
Potential value	Low in general. Very low at CBTS	Low	Low	Low
Nursery / breeding ground	No significant record	No significant record	No significant record	No significant record
Age	N/A	N/A	N/A	N/A
Abundance / Richness of wildlife	Low	Low	Low	Low
Ecological Value	Low in general. Very low at CBTS	Low	Low	Low

Table 5.6 Ecological Evaluation of Natural Rocky Shore Habitat within the Assessment Area

Criteria	Natural Rocky Shore Habitat
	Victoria Harbour WCZ	Western Buffer WCZ	Eastern Buffer WCZ	Tai Tam Bay
Naturalness	Largely natural, but subject to disturbance by human activities, reclamation and construction works.	Largely natural, but subject to disturbance by human activities, reclamation and construction works.	Largely natural, relatively undisturbed by human activities	Largely natural, relatively undisturbed by human activities
Size	Small	Small	Medium	Medium
Diversity	Low	Low	Moderate	Moderate
Rarity	No rare species were recorded.	No rare species were recorded.	No rare species were recorded.	No rare species were recorded.
Recreatability	Habitat is moderately re-creatable. Intertidal biota may recolonize hard substrata shores.	Habitat is moderately re-creatable. Intertidal biota may recolonize hard substrata shores.	Habitat is moderately re-creatable. Intertidal biota may recolonize hard substrata shores.	Habitat is moderately re-creatable. Intertidal biota may recolonize hard substrata shores.
Fragmentation	Highly fragmented. The intertidal habitats in the area were dominated by artificial intertidal habitats (e.g. vertical seawall).	Highly fragmented. The intertidal habitats in the area were dominated by artificial intertidal habitats (e.g. vertical seawall).	Slightly fragmented.	Slightly fragmented.
Ecological linkage	Not structurally and functionally linked to any highly valued habitat in close proximity.	Not structurally and functionally linked to any highly valued habitat in close proximity.	Not structurally and functionally linked to any highly valued habitat in close proximity.	Not structurally and functionally linked to any highly valued habitat in close proximity.
Potential value	Low	Low	Low	Low
Nursery / breeding ground	No significant record	No significant record	No significant record	No significant record
Age	N/A	N/A	N/A	N/A
Abundance / Richness of wildlife	Moderate	Moderate	Moderate.	Moderate.
Ecological Value	Low	Low	Low to moderate	Low to moderate

Table 5.7 Ecological Evaluation of Sandy Shore Habitat within the Assessment Area

Criteria	Sandy Shore Habitat
	Victoria Harbour WCZ	Western Buffer WCZ	Eastern Buffer WCZ	Tai Tam Bay
Naturalness	Low and subject to disturbance by human activities, reclamation and construction works.	Moderate. Largely undisturbed by physical modification and disturbance from recreational use.	Moderate. Largely undisturbed by physical modification and disturbance from recreational use.	Moderate. Largely undisturbed by physical modification and disturbance from recreational use.
Size	Very small	Small	Small	Small
Diversity	Very low	Low	Low	Very low
Rarity	No rare species were recorded.	No rare species were recorded.	No rare species were recorded.	No rare species were recorded.
Recreatability	High. Habitat is re-creatable	Moderate. Habitat is re-creatable.	Moderate. Habitat is re-creatable.	Moderate. Habitat is re-creatable
Fragmentation	High. Sandy shores formed a small portion of intertidal habitat in the area.	Moderate to high. Sandy shores formed a small portion of intertidal habitat in the area.	Moderate to high. Sandy shores formed a small portion of intertidal habitat in the area.	Moderate to high. Sandy shores formed a small portion of intertidal habitat in the area.
Ecological linkage	Not structurally and functionally linked to any highly valued habitat in close proximity.	Not structurally and functionally linked to any highly valued habitat in close proximity.	Not structurally and functionally linked to any highly valued habitat in close proximity.	Not structurally and functionally linked to any highly valued habitat in close proximity.
Potential value	Very low	Low	Low	Low
Nursery / breeding ground	No significant record	No significant record	No significant record	No significant record
Age	N/A	N/A	N/A	N/A
Abundance / Richness of wildlife	Very low	Low	Low	Very low
Ecological Value	Very low	Low	Low	Low

Table 5.8 Ecological Evaluation of Marine Waters/Coastal Waters Habitat within the Assessment Area

Criteria	Marine Waters/Coastal Waters Habitat
	Victoria Harbour WCZ	Western Buffer WCZ	Eastern Buffer WCZ	Tai Tam Bay
Naturalness	Habitats have been subjected to high degree of disturbance from urban development and fisheries and are under the influence of water pollutants from Pearl River and local urban discharges.	Habitats have been subjected to high degree of disturbance from urban development and fisheries and are under the influence of water pollutants from Pearl River and local urban discharges.	Habitats have been subjected to anthropogenic disturbance from urban development and are under the influence of water pollutants from local urban discharges.	Habitats have been subjected to some level of disturbance by fisheries vessel trawling.
Size	Habitat is large in extent.	Habitat is large in extent.	Habitat is large in extent.	Habitat is large in extent.
Diversity	No recent record of marine mammal	Only a few sightings of Chinese White Dolphin were recorded in previous years.	No recent record of marine mammal	No recent record of marine mammal
Rarity	No rare species were recorded.	Chinese White Dolphin is of conservation concern and protected under Cap. 170 and Cap. 586.	No rare species were recorded.	No rare species were recorded.
Recreatability	Low. This habitat cannot be easily recreated.	Low. This habitat cannot be easily recreated.	Low. This habitat cannot be easily recreated.	Low. This habitat cannot be easily recreated.
Fragmentation	Not fragmented.	Not fragmented.	Not fragmented.	Not fragmented.
Ecological linkage	Not ecologically linked to any highly valued habitat in close proximity.	Not ecologically linked to any highly valued habitat in close proximity.	Not ecologically linked to any highly valued habitat in close proximity.	Not ecologically linked to any highly valued habitat in close proximity.
Potential value	Low	Low	Low	Low
Nursery / breeding ground	No significant record	No significant record	No significant record	No significant record
Age	N/A	N/A	N/A	N/A
Abundance / Richness of wildlife	No recent record of marine mammal	Only a few sightings of Chinese White Dolphin were recorded in previous years.	No recent record of marine mammal	No recent record of marine mammal
Ecological Value	Very low	Low	Very low	Very low

5.82 The species of conservation interest recorded in the assessment area are summarised in Table 5.9.

Table 5.9 Species of Conservation Interest Recorded within the Assessment Area

Species	Locations Recorded	Protection Status	Distribution in Hong Kong
Benthic Fauna in Soft Bottom Subtidal Habitat
Amphioxus Branchiostoma belcheri	Tathong Channel, Tai Tam Bay near the proposed IMT casting basin	Class II National Key Protected Species. Categorized as Endangered in China Red Data Book.	Distributed in eastern waters near Sai Kung (Nam She Wan, Tai Long Wan, Long Ke Wan and Pak Lap Wan.
Hard Corals in Hard Bottom Subtidal Habitat
Oulastrea crispata	Hung Hom^(1), Causeway Bay, North Point, To Kwa Wan, Kai Tak, Aberdeen PTW, Sham Tseng, Tsing Lung Tau and Shek O Quarry^(1)	All hard corals are under the statutory protection of the Protection of Endangered Species of Animals and Plants Ordinance (Cap. 586).	Common and widespread
Acropora solitaryensis	Shek O Quarry		Uncommon
Balanophyllia sp.	Hung Hom^(1), Sham Tseng and Tsing Lung Tau		Common and widespread
Cyphastrea serailia	Shek O Quarry		Common and widespread
Goniopora stutchburyi	Shek O Quarry		Common and widespread
Favia speciosa	Shek O Quarry		Common and widespread
Favites pentagona	Shek O Quarry		Common and widespread
Montipora peltiformis	Shek O Quarry		Common and widespread
Pavona decussata	Shek O Quarry		Common and widespread
Porites lutea	Shek O Quarry		Common and widespread
Psammocora superficialis	Shek O Quarry		Abundant and widespread
Tubastrea sp.	Shek O Quarry		-
Marine Mammals in Marine Waters/Coastal Waters Habitat
Chinese White Dolphin Sousa chinensis	Western Buffer WCZ	Protected under Wild Animals Protection Ordinance (Cap. 170) and Protection of Endangered Species of Animals and Plants Ordinance (Cap. 586); Class I National Key Protected Species. Categorized as Near Threatened in IUCN Red Data Book, and listed in ‘Appendix I’ in the CITES.	Locally found in western waters, especially the North and West Lantau waters.

Note:

(1) Species of conservation interest recorded within the proposed marine-based works areas.

5.83 Based on the ecological baseline conditions as described in the above sections, most of the habitats within the assessment area are of low ecological value. These habitats were subject to certain degree of human disturbance and supported only low diversity of marine resources. Most species recorded are common and widespread in Hong Kong.

5.84 Subtidal soft bottom habitat in Eastern Buffer WCZ and Tai Tam Bay is considered to have low to moderate and moderate ecological value respectively. The proposed IMT casting basin would be within Tai Tam Bay. Species of conservation interest Amphioxus Branchiostoma belcheri was recorded in these waters during the survey conducted under this EIA. Although moderately abundance of juvenile occurred in wet season, the abrupt drop in number in the dry season suggests that the condition of Shek O Quarry is not suitable for its continual survival after settlement (refer to Section 5.49). Benthic species diversity in the subtidal soft bottom habitats in these waters was moderate to high (H’ between 2 and 3 or higher). The ecological value of the subtidal soft bottom habitat in the rest of the assessment area is ranked low including the area where the proposed cross harbour section of the Project is located.

5.85 Ecological value of subtidal hard bottom habitat in the southern portion of Western Buffer WCZ, Eastern Buffer WCZ and Tai Tam Bay is considered to be low to moderate. Moderate coral diversity and abundance of hard coral or/and octocoral were recorded at restricted number of sites within these waters. No rare species was recorded. Having low species diversity and coverage, the ecological value of the subtidal hard bottom habitat of the proposed works area in Victoria Harbour and the rest of the assessment area were considered low.

5.86 With a species diversity and richness typical of other similar semi-exposed natural shores in Hong Kong, the ecological value of natural rocky shore in Eastern Buffer WCZ and Tai Tam Bay is ranked low to moderate. Natural rocky shore in the rest of the assessment area including all proposed marine-based works areas has a low ecological value.

5.87 There are only a few sandy shores in the current assessment area. The ecological value of this habitat was generally low with low species diversity.

Identification, Prediction and Evaluation of Environmental Impacts

5.88 The scope and extent of the Project works are described in detail in Section 3 of this Report. Figure No. NEX/2213/C/331/ENS/M51/001 shows the proposed marine works within Victoria Harbour. Impacts to marine ecological resources may occur during the construction and operation phases. The impacts may be derived from direct loss of the habitats or indirect disturbance through changes to key water quality parameters.

Construction Phase

Direct Impact

Potential Habitat Loss due to Construction Activities within Victoria Harbour

5.89 During the construction phase, the proposed alignment of the Project crossing the harbour would be constructed using IMT method. The seabed along the alignment would be dredged in phases. The IMT tunnel construction is tentatively scheduled to commence in 2016 and for completion in 2017. Benthic organisms and coral colonies within the footprint of the dredging area would be affected. It was estimated that approximately 15 ha of seabed (both subtidal soft bottom habitat and subtidal hard bottom habitat) would be temporarily lost due to the IMT tunnel construction. As discussed in Section 5.38 to 5.42, 5.53 to 5.54, and 5.64 to 5.66, the subtidal soft bottom habitat, subtidal hard bottom habitat and the associated flora and fauna species are ranked as low ecological importance (low value). In addition, temporary loss of these habitats would be reinstated after the construction works and similar assemblages of flora and fauna are expected to re-colonize. Hence, the temporary loss of these habitats would not result in significant adverse impact on the marine ecological system in the Project area and its vicinity.

5.90 When bedrock or large bounders are encountered along the IMT section, ad hoc small scale underwater blasting may be required. Based on the preliminary design information, underwater blasting is identified as a provisional arrangement at the middle of the fairway and south of Hung Hom Landfall (Figure NEX2213/C/331/ENS/M51/001 refers). Generally speaking, shock waves generated from underwater blasting could kill marine organisms such as the hard coral species. Previous study (Wright, 1982) showed that an overpressure greater than 100 kPa would result in mortality of fishes. The area with an overpressure greater than 100 kPa is known as lethal zone. It is expected that wildlife outside the lethal zone would be mildly affected. Under this Project, the charge of explosives has been properly designed so that the lethal zone would be confined within the dredging area (i.e. the radius of the lethal zone for the explosive used would be controlled within 17 m and 30 m at the seafront off Hung Hom and the middle of the Victoria Harbour, respectively) (Figure NEX2213/C/331/ENS/M51/001 refers). Hence, it is anticipated that the subtidal soft bottom habitat and the associated benthic organisms within the lethal zone of about 1.7 ha would be affected. The benthic communities recorded in the affected area were common in Hong Kong. In addition, it is expected that the lethal zone would be gradually recolonized after the construction phase. Apart from the coral colonies affected by dredging activities, no additional coral colonies would be lost due to the underwater blasting works. Therefore, the impact, which is reversible and temporary (i.e. about 12 months), is considered to be insignificant.

5.91 The tip of the Hung Hom Freight Pier would be demolished for construction of the IMT tunnel. Upon completion, the Pier would be reinstated. Temporary loss of approximately 180 m long seawall due to the Hung Hom Freight Pier demolition would be expected. Both subtidal hard bottom habitat and artificial seawall habitat are associated with the affected coastline. Demolition of the Hung Hom Freight Pier would affect the intertidal organisms and the corals attached to the seawalls. Nevertheless, the only species of conservation interest identified within these affected habitats were the small and isolated common hard coral species, including Oulastrea crispata and Balanophyllia sp. It is anticipated that, intertidal and subtidal assemblages similar to those recorded in the field surveys, would settle on and recolonize the newly constructed pier. In view of the sparse coverage, small size, low diversity and commonness, the affected coral colonies are considered to have low ecological value.

5.92 Construction of the proposed alignment of Project at Hung Hom Landfall and within CBTS and north of the CBTS breakwater would involve temporary reclamation. The cofferdam works at Hung Hom Landfall would last from 2015 to 2016, while the temporary reclamation at CBTS would last from 2015 to 2018. The works at Hung Hom Landfall would also involve the demolition of several existing fender piles under the Hung Hom Bypass. These piles will be reprovisioned upon the completion of the tunnel section. These reclamation works would affect the intertidal and subtidal organisms. It was estimated that approximately 120 m long artificial seawall (including the corals attached to the seawalls at Hung Hom Landfall) and approximately 2.4 ha of subtidal soft bottom habitat would be temporarily loss due to the reclamation works. The field survey results showed that only limited intertidal and subtidal fauna of low ecological value were found within the temporary reclamation area (refer to Section 5.38 to 5.42, 5.53 to 5.54, 5.64 to 5.66, 5.40 to 5.41, 5.53 and 5.64 to 5.65). Furthermore, these habitats to be temporarily lost would be reinstated upon the construction works and similar assemblages of fauna are expected to re-colonize. Significant adverse ecological impact due to temporary loss of these habitats and associated wildlife is not anticipated.

5.93 In summary, since all the marine habitats that would be lost due to the Project within Victoria Harbour are of low ecological values and the potential ecological impacts arising from the loss would be reversible and temporary, no significant adverse ecological impact is expected.

Potential Habitat Loss due to Construction of IMT Casting Basin at Shek O Quarry

5.94 Shek O Quarry is located on the south-western side of the D’ Aguilar Peninsular of the Hong Kong Island, and has been operated since 1964. The site was previously adopted as quarry and IMT casting basin for Lantau Airport Rail. Under the Shek O Quarry rehabilitation plan, the existing quarry basin was transformed into a marine cove by removing the existing gates of the quarry site. The rehabilitation works was substantially completed recently in November 2010. No significant change in the existing marine environment outside the marine cove due to the rehabilitation works is expected.

5.95 Under this Project, it is proposed to use Shek O Quarry basin as a casting yard for IMT in 2014 - 2017. Based on the current design, no dredging would be required for construction of the casting basin. The outcrop island and the gate frames of the existing quarry would be retained. The construction works would basically involve installation of the gates back in place at the gate frames and draining water within the marine cove through the gate. Since the formation of the IMT casting basin would not involve marine construction works, the existing marine habitats outside the marine cove would not be affected. 

5.96 Upon the completion of the rehabilitation work, it is expected that the marine cove would gradually be recolonized by some pioneer marine species.  The IMT casting basin would lead to temporary loss of the newly established marine habitat in the marine cove with a size of about 10 ha and the associated fauna.  However, in view of that the age of the marine habitat would be young at the time when the Project commences, the ecological value is expected to be low.  After completion of all the IMT fabrication and construction works, the site will be reinstated to the layout originally planned under the Rehabilitation of Shek O Quarry project, which will involve the removal of the gates to transform the casting basin back into a marine cove. In view of the low ecological value of the marine habitat and reversible and temporary nature of the impact, adverse ecological impact due to the loss of the marine habitat and associated fauna is not expected.  

5.97 A summary of the marine habitat loss due to the proposed marine works of the Project is presented in Table 5.10.

Table 5.10 Summary of Marine Habitat Loss due to the Proposed Construction Works

Construction works	Habitat affected	Area / Length	Nature of Impact to Marine Habitat
Temporary reclamation at Hung Hom Landfall	Subtidal soft bottom habitat	~0.88 ha	Temporary loss
	Subtidal hard bottom habitat and artificial seawall habitat	~30 m
Demolition of the tip of Hung Hom Freight Pier	Subtidal hard bottom habitat and artificial seawall habitat	~180 m	Temporary loss
Dredging work (including provisional underwater blasting work)	Subtidal soft bottom habitat	~15 ha (including 1.7 ha lethal zone due to underwater blasting work)	Temporary loss
Temporary reclamation within CBTS	Subtidal soft bottom habitat	~1.5 ha	Temporary loss
	Artificial seawall habitat	~ 90 m
Construction of Shek O Casting Basin