7 MARINE ECOLOGICAL IMPACT

7.1 Introduction

7.1.1 This section presents the ecological baseline resources within the Assessment Area, and the results of assessment of potential ecological impacts resulting from the construction and operation of the Project, which has been conducted in accordance with the criteria and guidelines as stated in Annexes 8 and 16 of the Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM) as well as the requirements given in Clause 3.4.7 and Appendix E of the EIA Study Brief (No. ESB-302/2017).

7.1.2 The baseline conditions of the ecological components of the marine environment were evaluated based on the information available from literature and field surveys conducted for the purposes of this EIA. Measures required to mitigate any identified adverse impacts are recommended, where appropriate, and residual impacts are assessed.

7.2 Environmental Legislation, Standards and Guidelines

7.2.1 This assessment makes reference to the following 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:

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

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

· 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.

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

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

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

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

· Wild Animals Protection Ordinance (Cap. 170) – designated wild animals are protected from being hunted, and 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 protected animals, was last revised in June 1997.

· Town Planning Ordinance (Cap. 131) – provides for the designation of Coastal Protection Areas, Sites of Special Scientific Interest (SSSIs), Conservation Area (CA), Country Park, Green Belt (GB) or other specified uses that promote conservation or protection of the environment.

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

· 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.

· Water Pollution Control Ordinance (Cap. 358) – aims to control water pollution in waters of Hong Kong. Water Control Zones (WCZs) are designated with individual water quality objective to promote the conservation and best use of those waters in the public interest.

· Protection of Endangered Species of Animals and Plants Ordinance (Cap. 586) – provides protection for certain plant and animal species through controlling or prohibiting trade in the species. Certain types of corals are listed in Schedule 1 of the Ordinance, including Blue coral (Heliopora coerulea), Organ pipe corals (family Tubiporidae), Black corals (order Antipatharia), Stony corals (order Scleractinia), Firecorals (family Milleporidae) and Lace corals (family Stylasteridae). Cetaceans including whales, dolphins, porpoises, and rorquals are also listed under Schedules 1 and 2 of the Ordinance. The import, export and possession of scheduled corals, no matter dead or living, are restricted.

· This section also makes reference to the following international conventions and national legislations:

· The International Union for Conservation of Nature (IUCN) Red List of Threatened Species provides taxonomic, conservation status and distribution information on taxa that have been evaluated using the IUCN Red List Categories and Criteria. The system is designed to determine the relative risk of extinction. The main purpose of the IUCN Red List is to classify and highlight taxa facing a higher risk of global extinction.

· The People’s Republic of China (PRC) National Protection Lists of Important Wild Animals and Plants provides detailed Category I and Category II key protected animals and plant species under the mainland China legislation. The list was last updated in November 2002.

7.3 Assessment Methodology

Assessment Area

7.3.1 The Project site is situated between the HKBCF Island and the HKIA, at the south of the existing SkyPier. The Bonded Vehicular Bridge serves as a connection between the ITT at the south of SkyPier at HKIA and HKBCF Island. The marine section of the site is a sea channel between HKIA and HKBCF Island. The Project involved both land-based and marine works.

7.3.2 In accordance with Clause 3.4.7.2 of the EIA Study Brief (No. ESB-302/2017), the Assessment Area shall be the same as the Assessment Area for Water Quality Impact Assessment or the areas likely to be impacted by the Project. As no open sea dredging will be involved and the installation of steel pile casing would create a confined environment for excavation, a 500 m Assessment Area from the Project area is defined for the purpose of the marine ecological impact assessment (refer to Figure 7.1). Potential impacts on sites of conservation importance in the vicinity of Assessment Area, and ecological impact of marine traffic arising from the works within and outside of the Assessment Area were also assessed.

Literature Review

7.3.3 Following the collation and review of existing ecological baseline information, relevant available literature is listed in Table 7.1.

Table 7.1 Baseline Information of Ecological Resources in the Assessment Area

Relevant Literatures	Corals	Benthos	Intertidal Community	Marine Mammals
(1) Monitoring of Marine Mammals in Hong Kong Waters (2016-17) Final Report (1 April 2016 to 31 March 2017 (AFCD, 2017)				✓
(2) Tung Chung New Town Extension – EIA Report (CEDD, 2015)	✓	✓	✓	✓
(3) Expansion of Hong Kong International Airport into a Three-Runway System – EIA Report (AAHK, 2014)	✓	✓	✓	✓
(4) Expansion of Hong Kong International Airport into a Three-Runway System – Construction Phase Monthly EM&A Report No.24 (AAHK, 2018)	✓	✓	✓	✓
(5) Hong Kong - Zhuhai - Macao Bridge Hong Kong Boundary Crossing Facilities – EIA Report (HyD, 2009a)	✓	✓	✓	✓
(6) Hong Kong - Zhuhai - Macao Bridge Hong Kong Boundary Crossing Facilities – Monthly EM&A Report No. 37 (HyD, 2018a)	✓	✓	✓	✓
(7) Hong Kong - Zhuhai - Macao Bridge Hong Kong Link Road – EIA Report (HyD, 2009b)	✓	✓	✓	✓
(8) Hong Kong - Zhuhai - Macao Bridge Hong Kong Link Road – Section between HKSAR Boundary and Scenic Hill – Monthly EM&A Report (Dec 2017) (HyD, 2018b)	✓	✓	✓	✓
(9) Tuen Mun – Chek Lap Kok Link – Investigation – EIA Report (HyD, 2009c)	✓	✓	✓	✓
(10) Tuen Mun – Chek Lap Kok Link – Investigation – EM&A Manual (HyD, 2009d)	✓	✓	✓	✓
(11) Consultancy Study on Marine Benthic Communities in Hong Kong (AFCD, 2002)		✓

Identification of Information Gap

7.3.4 Chinese White Dolphin (CWD) surveys have been conducted in Hong Kong waters since 1996 and have also been conducted off North Lantau for various EIA studies recently. The territory-wide AFCD dolphin monitoring programme covers nine marine zones including Western and North Lantau waters with vessel survey transects (AFCD, 2017). Further dolphin surveys were conducted in North Lantau waters during the EIA studies for Tuen Mun – Chek Lap Kok Link (TMCLKL) and Three-Runway System (3RS) projects, and EM&A monitoring for Hong Kong Boundary Crossing Facilities (HKBCF), Hong Kong Link Road (HKLR) and 3RS projects. The information from these recent studies is sufficient for establishing the baseline conditions of CWDs within the Assessment Area in particular in the vicinity of the Project Site. Field surveys for CWDs for the Project are therefore not necessary.

7.3.5 Based on the review of available information on marine ecological resources, a site-specific information gap was identified. Ecological surveys including coral survey, intertidal survey and benthos survey were conducted from March to September 2017 to fill in the gap. The ecological surveys followed the requirements as stipulated under EIAO Guidance Note No. 7/2010 Ecological Baseline Survey for Ecological Assessment. All field surveys were carried out in such ways that no unnecessary stress or damage to the existing habitats and wildlife was resulted. The surveys are described in details in the sections below.

Table 7.2 Ecological Survey Schedule

Survey	Mar 2017	May 2017	Sep 2017
Coral Survey		✓
Benthos Survey	✓
Intertidal Survey	✓		✓

Ecological Survey Methodology

Coral Survey

7.3.6 Spot-check dive surveys were conducted, with regular zig-zag dive routes to record presence of any coral in May 2017. Subtidal substrata (hard substratum seabed and seawall, etc.) at the proposed spot-check dive locations were surveyed for any presence of coral colonies, including hard corals (order Scleractinia), octocorals (sub-class Octocorallia) and black corals (order Antipatharia). Attention was also given to identify the presence of other species of conservation importance.

7.3.7 As corals were recorded during the spot-check dives, a more detailed Rapid Ecological Assessment (REA) was carried out with reference to DeVantier et al. (1998) (see Appendix 7.1 for details). Three 100 m REA transects were proposed, based on the preliminary results from the spot-check dives (refer to Figure 7.1). For each transect, the locations (Global Positioning System, GPS) of dive routes, distance surveyed, number of colonies, sizes and types of corals, their coverage, abundance, condition, translocation feasibility and the conservation status of coral species in Hong Kong waters were recorded.

Benthos Survey

7.3.8 To survey the marine soft bottom benthic fauna, grab sampling of seabed sediment was carried out at three locations in March 2017 (refer to Figure 7.1). At each sampling site, three replicates of grab samples over a 0.1 m² area seabed substrate were collected using a van Veen grab and sample was sieved through 0.5 mm sieves and stained with Rose Bengal. Collected organisms were counted, weighed and identified to the lowest practicable taxon as possible.

7.3.9 Abundance, biomass, species diversity H’ and evenness J were calculated for pooled data, using the formulae:

H’= -å ( Ni / N ) ln ( Ni / N ) ; and

J = H’ / ln S

where S is the total number of species in the sample

N is the total number of individuals

Ni is the number of individuals of the i^th species

Intertidal Survey

7.3.10 Survey on intertidal communities was conducted at the four proposed survey locations in March 2017 (refer to Figure 7.1) by line transect method, in order to establish an ecological profile on the intertidal habitats located in the Assessment Area.

7.3.11 At each survey location, a qualitative or walk-through survey was conducted to find out the intertidal flora and fauna present and their occurrence in the survey location. It helped to assess whether the sampling exercise in the later quantitative survey had collected representative data (e.g. the number and type of species encountered) and whether the sampling effort was deemed adequate. Effort spent in such qualitative or walk-through survey, such as number of surveyors involved and the time spent were recorded and provided as appropriate.

7.3.12 After the walk-through survey, quantitative survey was conducted using line transect method. One line transect was deployed at each proposed survey location. The transects were laid perpendicular to shoreline from high water mark down to low water mark during the low tide period (tide level below 1 m). Along each transect, standard ecological sampling quadrats (dimensions 0.5 m x 0.5 m) were laid at 1 m intervals (or other suitable quadrat dimension and interval distance depending on the field situation).

7.3.13 Intertidal epifauna and flora within each quadrat were identified and enumerated. In general, mobile fauna were counted in terms of abundance per unit area. Sessile organisms such as barnacles, oysters and algae were estimated in terms of percentage cover per fixed area. Intertidal fauna were identified to species level as far as possible. Representative photographs for the identified intertidal habitat and flora / fauna species were taken.

7.4 Description of the Environment

Physical Environment of the Site

7.4.1 The marine section of Bonded Vehicular Bridge between the HKBCF Island and the HKIA crosses an embayment with bottom-necked topography connecting with the Northern Western Water Control Zone by a narrower channel (about 330 m in length). Marine traffic was busy within the Assessment Area to and from the Skypier at the Airport and around the Airport Fire Contingent Main Fire Station northeast to the Skypier.

7.4.2 The coastlines of the Airport and HKBCF Island are predominately sloping boulder-form and vertical artificial seawalls, except that the northeast shores of Airport Island contain some remnant shores of the original Chek Lap Kok Island. All other original coastlines of Chek Lap Kok have been lost during reclamation for the HKIA. The recent age, design, homogeneity, orientation and lack of habitat niches of the seawalls of Airport Island and HKBCF are likely to limit marine faunal abundance and diversity along the shorelines. According to the AFCD dolphin monitoring programme, the Assessment Area located in Northeast Lantau waters is unlikely to be the preferred habitat for Chinese White Dolphins (Sousa chinensis) in recent years.

Recognised Site of Conservation Importance

7.4.3 The Brothers Marine Park (BMP) is situated in the northern Lantau waters. It was designated as a marine park in December 2016 as a mitigation measure for the HKZMB HKBCF project for the protection and enhancement of CWD habitats within the areas. The Marine Park is located to the east of the HKBCF and is about 1.5 km away from the Project. Waters within the BMP are important feeding grounds for CWDs.

7.4.4 The Sha Chau and Lung Kwu Chau Marine Park (SCLKCMP) was designated in November 1996 for conservation of the CWDs. It is located in the open waters on the western side of Hong Kong and is about 5 km away from the Project. With the deployment of artificial reef, the Marine Park has very rich fisheries resources, particularly fishes of Engraulidae, Sciaenidae and Clupeidae which are the primary food sources for CWDs. It therefore serves as an important feeding ground for the dolphins.

Literature Review

Coral Colonies

7.4.5 At the eastern shore of the Airport Island, low abundance of Gorgonian coral Echinomuricea sp. and one species of ahermatypic coral Balanophyllia sp. were recorded on the boulders of the artificial seawall (HyD, 2009a). Beyond the seawalls, the seabed turned into muddy substrates, and no epifauna was recorded.

Benthos

7.4.6 Grab samples were taken near the current Project site in a territory-wide marine benthic communities study (AFCD, 2002) - western waters with 29 sampling stations, covering Urmston Road, Deep Bay and North Lantau. Station 18 is more relevant to the Project as this station was located in the vicinity of the Project footprint. Station 18 was located to the north of Airport Northeast corner. The water depth of Station 18 was 8 m, and in summer the mean Total Organic Matter (TOM) was 3.64%, lower than the average in Hong Kong (6.04%). The species richness index (d) was 5.62, the species, individual and biomass density were 38 species, 1,444 individuals, and 1,347.68 g/m² respectively. The diversity index, H’, was 1.52 and evenness, J, was 0.42. Common species in the group of stations covering Station 18 included annelids of Mediomastus sp., Aglaophamus distranchis and Apionsoma trichocephalus.

7.4.7 The benthic communities inside the footprints of HKBCF reclamation (the waters offshore to the northeast coast of Airport Island) were investigated in the HKBCF EIA (HyD, 2009a). A total of 559 organisms from 80 taxa were collected from 9 sampling stations within the HKBCF reclamation area. No species of conservation importance was found.

Intertidal Communities

7.4.8 The intertidal communities at the artificial seawalls along the northeast coast of Airport Island were surveyed (HyD, 2009a). The seawalls were colonised by low abundance and diversity of intertidal fauna. The species recorded were all common in Hong Kong, including Acorn Barnacle Tetraclita squamosa, Rock oyster Saccostrea cucullata, False limpet Siphonaria japonica, Limpet Patelloida pygmaea & P. saccharina, and Nerite snails Neritina sp. No species of conservation importance was found.

Marine Mammals

7.4.9 The literature review was based upon the long-term monitoring data of CWDs collected by AFCD since 2011, as well as EIA studies and EM&A dolphin monitoring surveys for the HKBCF, HKLR and 3RS projects (HyD, 2018a; HyD, 2018b; AAHK, 2018). Previous survey data and subsequent analyses have provided a comprehensive baseline on Chinese White Dolphin (CWD) densities, distribution, abundance, breeding and foraging behaviour around Lantau waters.

7.4.10 West and North Lantau waters were once regarded as important foraging and nursing habitats for CWDs, while several hotspots including SCLKCMP and the BMP were frequently utilised by CWDs and their young calves until 2014. According to the marine mammal monitoring surveys conducted by AFCD, apparent range shifts from North Lantau to Northwest (confined to Lung Kwu Chau) and West Lantau, and from West Lantau to Southwest Lantau were observed from 2011 to 2016 (AFCD, 2017). Continuous decline in dolphin density and encounter rate were found particularly in Northeast Lantau waters (including the BMP, the proposed Project area and vicinity), where a 90% drop of dolphin abundance was recorded from 2003 to 2016. Unspotted calves were hardly seen within the same region since 2014. Similar trend was observed in the vessel-based line transect surveys for the HKBCF, HKLR and 3RS projects (HyD, 2018a; HyD, 2018b; AAHK, 2018). Land-based dolphin sightings recorded for these three projects largely concentrated on the north of Lung Kwu Chau far away from the proposed Project area.

7.4.11 Referring to the latest long-term dolphin monitoring programme by AFCD, moderate to high CWD densities, densities of feeding dolphins and mother-calf pair were found in West Lantau waters and around SCLKCMP, where highest encounter rates of dolphin juveniles and calves were recorded. These were consistent with the latest dolphin monitoring records for the HKBCF, HKLR and 3RS projects. West Lantau waters and SCLKCMP are therefore considered as crucial habitats for this vulnerable species of conservation importance (IUCN, 2017) in Hong Kong.

Survey Findings

Coral Colonies

7.4.12 Spot-check dives were conducted along four spot check dive survey routes (D1 to D4) as shown in Figure 7.1. The GPS coordinates, route distance, maximum depth, minimum depth, bottom substrate and bottom visibility of the survey sites are summarised in Table 7.3. Representative photographs of the survey locations and coral colonies taken during survey are presented in Appendix 7.2.

Table 7.3 Physical Parameters of the Spot-Check Dive Locations

Site	GPS Coordinates (Starting Point)	Route Distance (m)	Max. Depth (m)	Bottom Substrate	Visibility (m)
D1	E 113°56'55.60" N 22°19'13.21"	660	4	Artificial Sloping Boulders	<0.5
D2	E 113°56'48.40" N 22°18'55.48"	650	4	Artificial Sloping Boulders	<0.5
D3	E 113°56'35.64" N 22°18'55.11"	350	7	Artificial Vertical Seawall	<0.5
D4	E 113°56'39.62" N 22°19'07.24"	200	5	Artificial Sloping Boulders	<0.5

7.4.13 The spot check sites were mainly composed of artificial sloping boulders and vertical seawall (refer to Appendix 7.2). Substrates beyond the maximum depth were all muddy and with visibility less than 0.5 m.

7.4.14 One species of hard coral Oulastrea crispata and one species of gorgonian coral Guaiagorgia sp. were found scattered on boulder surfaces and vertical seawall along the survey areas. These species are commonly found in western Hong Kong waters especially in turbid water. The coral coverage in the survey sites was generally low (less than 5%). Thick sediment was found on boulder surfaces. The partial mortality of gorgonian colonies are relatively high ranging from 20% to 70%.

7.4.15 The survey sites only support limited marine life. Other animals found during the surveys included common green mussel Perna viridis and rock oyster Saccostrea cucullata were recorded on the boulder surfaces and vertical seawall that scattered along the survey area. All animals found in the above sites are common species, occurred in low abundance and sparsely distributed. No rare nor species of conservation importance were recorded during the survey.

7.4.16 Three 100 m REA transects (REA1 to REA3) were surveyed (refer to Figure 7.1). The physical parameters of the REA transects are summarised in Table 7.4. Appendix 7.3 presents the coral colonies recorded during the REA survey.

Table 7.4 Physical Parameters of the REA Transects

Transect	GPS Coordinates (Starting Point)	GPS Coordinates (End Point)	Max. Depth (m)	Bottom Substrate	Visibility (m)
REA1	E 113°56'35.86" N 22°18'55.30"	E 113°56'37.58" N 22°18'58.22"	3	Artificial Vertical Seawall	<0.5
REA2	E 113°56'37.72" N 22°18'58.75"	E 113°56'38.51" N 22°19'01.98"	3	Artificial Vertical Seawall	<0.5
REA3	E 113°56'39.80" N 22°19'08.60"	E 113°56'42.35" N 22°19'11.14"	3.5	Artificial Sloping Boulder	<0.5

7.4.17 The ecological and substratum attributes of the REA transects are given in Table 7.5. Sparse coverage (1-5%) of gorgonian coral and hard coral was recorded in all transects. The substratum along the transects were mainly made up of artificial sloping boulders and artificial seawalls.

7.4.18 One species of hard coral (Oulastrea crispata) was recorded along the transects. A total of 13 colonies of Oulastrea crispata coral colonies (refer to Appendix 7.3) were recorded in REA3 during the REA survey, and all of them were grown on the boulder surfaces. The coral colonies were of small size (about 3 to 15 cm in diameter). All the hard coral colonies were in fair to unhealthy conditions.

7.4.19 One species of octocoral Guaiagorgia sp. was recorded along the transects. A total of 18, 23 and 26 colonies of Guaiagorgia sp. coral colonies (refer to Appendix 7.3) were recorded in REA1, REA2, REA3 respectively during the REA surveys, and they were grown on either the artificial vertical seawall or boulder surfaces. The coral colonies were of small size (about 6 to 26 cm in height) in all transects. Partial mortality rate at each Guaiagorgia sp. colonies was relatively high ranging from 20% to 70%, which showed that the gorgonian colonies were in unhealthy conditions.

7.4.20 A total of 80 coral colonies (67 Guaiagorgia sp. and 13 Oulastrea crispata) were recorded along the three REA transects. All of them were recorded from the boulder surfaces. The coral colonies at REA transects were found at around 2 to 3.5m below water.

7.4.21 Apart from the isolated patches of small coral colonies, some common marine invertebrate such as green mussel Perna viridis and rock oyster Saccostrea cucullata were recorded along the REA transects. No other rare nor species of conservation importance were recorded during survey.

Table 7.5 Transects Ranking of Percentage Cover of Ecological and Substratum Attributes of the REA Transects

Ecological Attributes	REA1	REA2	REA3
Hard Coral	0	0	0.5
Octocoral (soft corals and gorgonians)	0.5	0.5	0.5
Black Corals	0	0	0
Dead Standing Corals	0	0	0
Substratum Attributes	REA1	REA2	REA3
Bedrock/continuous pavement	5	5	0
Boulder Blocks (diam.>50cm)	0	0	5
Boulder Blocks (diam.<50cm)	0	0	1
Rubble	0	0	0
Other	0	0	0
Soft Substrata	0	0	0
Sand	0	0	0
Mud/Silt	0	0	0

* Rank of percentage cover: 0 = None recorded; 0.5 = 1-5%; 1 = 6-10%; 2 = 11-30 %; 3 = 31-50%;
4= 51-75 %; 5 = 76-100%.

Benthos

7.4.22 A benthos survey was conducted at four sampling sites (B1 to B4) (refer to Figure 7.1). B1 was located in a temporary works site area for viaduct construction. B2 and B3 were located along the proposed alignment of the Bonded Vehicular Bridge. B4 was located south from the proposed Bonded Vehicular Bridge. The sediments vary across the sampling sites. At B1, the sediments were mixture of soft mud (~60%) and gravels (~40%). Since B1 was located close to the artificial shore of HKBCF Island, the gravels are probably construction aggregates for HKBCF reclamation or coastal modification works. The sediment textures were mainly soft mud (90-95%) at the rest of sampling sites. The sediment colour was grey with a thin, brown surface layer. Black colour was observed at the deeper layer of B4 sediments. Mild sediment odour of hydrogen sulphite was detected in B3 and B4 sediments. It indicated the mild low oxygen condition or organic enrichment in the confined sea channel.

7.4.23 A total of 235 benthos fauna were collected in the dry sampling season (refer to Table 7.6). They were identified to 44 taxa, while 41 taxa were identified to genus or species levels. The most diverse phylum was Annelida (26 polychaete taxa), followed by Mollusca (5 bivalve species, 3 gastropod taxa, 1 scaphopod species), Arthropoda (3 amphipod taxa, 1 shrimp taxon, 1 copepod taxon). Other less diverse phyla (1-2 taxa) were Echinodermata (sea cucumber, brittle star), Cnidaria (sea pen) and Nemertea. All species are commonly found in Hong Kong. No benthic species of conservation importance were recorded. A list of species recorded during benthos surveys is attached in Appendix 7.7.

Table 7.6 Total Abundance and Biomass of Each Phylum

Phylum	No. of Individuals	Percentage (%)	Biomass (g)	Percentage (%)
Annelida	124	53	0.5861	5
Mollusca	52	22	1.4926	14
Arthropoda	34	14	0.1044	1
Nemertea	15	6	0.3603	3
Echinodermata	8	3	8.2337	75
Cnidaria	2	1	0.2255	2
Total	235	-	11.0026	-

7.4.24 The five most abundant fauna recorded at each sampling sites are presented in Table 7.7. For sampling site B1, Prionospio malmgreni (120 ind./m², 30%) was relatively more common at low-moderate density. For B2, Mediomastus spp. (33 ind./m², 27%) were common taxa at low-moderate density. For B3, Paratapes undulates (23 ind./m², 23%) was common taxon at low density. For B4, Theora lata (30 ind./m², 19%) was common taxon at low density. Other recorded taxa were low in densities (≤ 20 ind./m²).

Table 7.7 Five Most Abundant Fauna at Each Sampling Site

Sampling Site	Group		Species Name	Density (ind./m²)	Biomass (g/m²)	Relative Abundance (%)
B1	P		Prionospio malmgreni	120	0.1213	30
	N		Nemertea spp.	37	0.0343	9
	A		Corophiinae spp.	37	0.0133	9
	B		Paratapes undulatus	13	1.2983	3
	G		Calyptraea spp.	13	0.1660	3
B2	P		Mediomastus spp.	33	0.1613	27
	B		Theora lata	20	0.8367	16
	P		Glycinde gurjanovae	13	0.0440	11
	A		Corophiinae spp.	13	0.0110	11
	P		Sigambra hanaokai	10	0.0067	8
B3	B		Paratapes undulatus	23	0.0520	23
	G		Philine spp.	17	0.0670	17
	P		Aglaophamus dibranchis	10	0.0630	10
	Cn		Virgularia spp.	7	0.7517	7
	G		Episiphon kiaochowwanense	7	0.5470	7
B4	B	Theora lata		30	1.0173	19
	A	Corophiinae spp.		27	0.0107	17
	G	Philine spp.		17	0.0103	11
	Ec	Protankyra bidentata		10	15.5323	6
	P	Aglaophamus dibranchis		10	0.1113	6

Note: A = Amphipod, B = Bivalve, Cn = Cnidaria, Ec = Echinodermata, G = Gastropod, N = Nemertean, P = Polychaete.

7.4.25 Details on the number of species, abundance, biomass, Shannon-weaver Diversity Index (H’) and Pielou’s Species Evenness (J) recorded at each sampling site are presented in Table 7.8.

7.4.26 B1 was moderate in species number (29 spp./0.3m²) and high in density (403 ind./m²). The taxa distributions were quite even resulting in moderate J value (0.82). The H’ value was at moderate level (2.76).

7.4.27 For B2, B3 and B4, the species numbers (12-19 spp./0.3m²) and densities (100-157 ind./m²) were at low levels. The H' (2.20, 2.38 and 2.61) and J values (0.88, 0.90 and 0.88) of the sampling sites were at moderate level.

7.4.28 The biomasses of all sampling sites were varied between low to moderate level (3.15-18.70 g/m²), depending on the presence of large sized sea cucumber Protankyra bidentate.

Table 7.8 Number of Species, Abundance, Biomass, Species Diversity and Evenness at Each Sampling Site

Sampling Site	B1	B2	B3	B4
Number of species (spp./0.3 m²)	29	12	14	19
Abundance (ind./m²)	403	123	100	157
Biomass (g/m²)	3.15	13.07	1.76	18.70
Species diversity (H’)	2.76	2.20	2.38	2.61
Species evenness (J)	0.82	0.88	0.90	0.88

7.4.29 The marine benthic community was spatially divided into four groups in Hong Kong waters (Tolo Harbour, Eastern and Southern waters, Victoria Harbour, Deep Bay) (Shin et al., 2004) according to a territory-wide survey conducted by AFCD (2002). Waters of ‘Eastern and Southern waters’ group was characterised as unpolluted while that of other groups suffered from long-term sewage pollution (details see EPD, 2006). Table 7.9 shows the biodiversity index (H’) and species evenness (J) of benthic communities of the four groups as well as the sea channel of present survey.

7.4.30 The mean H’ of the four sampling sites was 2.49, which was higher than the other three polluted water groups ‘Tolo Harbour’ (1.36), ‘Victoria Harbour’ (1.64) and ‘Deep Bay’ (2.32). Moreover, the H’ and J values of the present survey were similar to unpolluted ‘Eastern and Southern waters’ group, reflecting healthy benthic community along the sea channel.

Table 7.9 Mean Species Diversity (H’) and Species Evenness (J) of Benthic Communities at Different Waters

	Sea Channel (Present Survey)	Tolo Harbour⁽¹⁾	Eastern & Southern ⁽¹⁾	Victoria Harbour⁽¹⁾	Deep Bay ⁽¹⁾
H’	2.49	1.36	2.82	1.64	2.32
J	0.87	0.83	0.81	0.44	0.73

Sea Channel

(Present Survey)

Tolo Harbour⁽¹⁾

Eastern &

Southern ⁽¹⁾

Victoria

Harbour⁽¹⁾

Deep Bay ⁽¹⁾

H’

2.49

1.36

2.82

1.64

2.32

0.87

0.83

0.81

0.44

0.73

Note: (1) Shin et al. (2004).

Intertidal Communities

7.4.31 An intertidal ecological survey was conducted along the sea channel between the Airport and the HKBCF Island. Four intertidal sampling sites (T1 – T4) were surveyed. T1 and T2 were located at the Airport island side, T3 and T4 were located at the HKBCF island side (refer to Figure 7.1). T1, T3 and T4 are composed of artificial sloping boulders while T2 is composed with artificial vertical seawall. Representative photographs taken during survey are attached in Appendix 7.4.

7.4.32 A total of 25 species of fauna and flora were recorded during the walk through survey along the four survey sites from dry and wet season (refer to Table 7.10). T1 showed the highest number of species, while T3 and T4 showed a relatively low number of species. All the species recorded during the walk-through survey are common and no species of conservation importance were recorded. Raw data recorded during intertidal surveys during dry season and wet season are presented in Appendix 7.5 and Appendix 7.6, respectively.

Table 7.10 Intertidal Species Recorded during the Walk-Through Survey

Species Name	Distribution in Hong Kong	Dry Season				Wet Season
Species Name	Distribution in Hong Kong	T1	T2	T3	T4	T1	T2	T3	T4
Encrusting Algae
Kyrtuthrix maculans	Common	x	x	x	x	x	x	x	x
Hildenbrandia rubra	Very Common	x	x			x	x
Algae
Enteromorpha spp.	Common			x	x			x	x
Gelidium pusillum	Common	x	x	x	x	x	x	x	x
Ulva spp.	Common	x	x	x	x	x	x	x	x
Sessile Invertebrates
Barnacles
Balanus amphitrite	Very Common			x	x			x	x
Capitulum mitella	Very Common	x	x			x	x
Tetraclita squamosa	Very Common	x	x			x	x
Bivalves
Barbatia virescens	Common	x				x
Saccostrea cucullata	Very Common	x	x	x	x	x	x	x	x
Septifer virgatus	Very Common	x	x			x	x
Mobile Invertebrates
True Crabs
Crapsus albolineatus	Common	x		x
Sea Slaters
Ligia exotica	Common	x	x	x	x	x	x	x	x
Limpets/False Limpets
Cellana grata	Very Common	x	x			x	x
Cellana toreuma	Very Common	x	x	x	x	x	x	x	x
Patelloida saccharina	Very Common	x	x			x	x
Siphonaria japonica	Common	x	x			x	x
Nerites
Nerita albicilla	Common	x	x			x	x
Periwinkle
Littoraria articulata	Common	x	x	x	x	x	x	x	x
Echinolittorina trochoides	Very Common	x	x			x	x
Echinolittorina radiata	Very Common	x	x			x	x
Monodonta labio	Very Common	x	x	x	x	x	x	x	x
Whelks
Thais luteostoma	Common	x	x			x	x
Thais clavigera	Very Common	x	x			x	x
Morula musiva	Very Common	x	x			x	x
Total No. of Species		23	21	11	11	23	21	11	11

7.4.33 During quantitative line transect survey conducted in dry season, 8 to 16 (Site T1:10, Site T2:16, Site T3:8, Site T4:8) species were recorded at the four transects. While quantitative line transect conducted survey during wet season, 10 to 22 (Site T1:22, Site T2:14, Site T3:10, Site T4:10) species were recorded (refer to Appendices 7.5 and 7.6). All the species recorded during the survey were either very common or common in Hong Kong.

7.4.34 Generally, encrusting algae Kyrtuthrix maculans, snails Echinolittorina radiata and Littoraria articulate, limpet Cellana grata, bivalve Saccostrea cucullata and top shell Monodonta labio were the common species at all sites. Bivalve Saccostrea cucullata, top shell Monodonta labio and barnacle Balanus amphitrite were the dominant species at the lower tidal level, while snails Echinolittorina radiata and Littoraria articulata were dominant at the higher tidal level. All the species recorded during the survey were either very common or common in Hong Kong. No species of conservation importance was recorded.

7.5 Evaluation of Baseline Ecological Value

7.5.1 The ecological importance of recorded habitats and species of conservation importance were evaluated in accordance with the criteria in Annex 8 of EIAO-TM and presented in Table 7.11 to Table 7.15 below.

Subtidal Hard Substrate Habitat

7.5.2 Subtidal hard substrate habitat within the Assessment Area is considered to be of low ecological value. All animals recorded in this habitat were common species and occurred in low abundance with sparse distribution. One species of hard coral Oulastrea crispata, one species of gorgonian coral Guaiagorgia sp., one green mussel Perna viridis and rock oyster Saccostrea cucullata were recorded. Although hard coral is a species of conservation importance, the size of the colonies recorded was small and in fair to unhealthy conditions. The ecological value of the habitat is rated as low.

Table 7.11 Evaluation of the Subtidal Hard Substrate Habitat within the Assessment Area

Criteria	Subtidal Hard Substrate Habitat
Naturalness	Very low. The substratum was under the effects of reclamation works and coastal modification. Mainly composed of artificial sloping bounders and vertical seawall.
Size	N.A.
Diversity	Low.
Rarity	Common habitat in Hong Kong Water. One common hard coral (Oulastrea crispata) species of conservation importance was recorded.
Re-creatability	Re-creatable.
Fragmentation	Unfragmented.
Ecological linkage	Generally linked with the open sea.
Potential value	Low
Nursery/breeding ground	Not a favorable breeding/nursery ground.
Age	Around 20 years along the HKIA coastline; about seven years along the coast of HKBCF
Abundance/Richness of wildlife	Low
Ecological value	Low

Subtidal Soft Bottom Habitat

7.5.3 Subtidal soft bottom habitat within the Assessment Area is considered to be of low ecological value. Moderate diversity and low to moderate abundance of benthos were recorded within the habitat. No species of conservation importance was recorded.

Table 7.12 Evaluation of the Subtidal Soft Bottom Habitat within the Assessment Area

Criteria	Subtidal Soft Bottom Habitat
Naturalness	Moderate. The substratum was however under the effects of reclamation works and coastal modification.
Size	N.A.
Diversity	B1: Moderate B2-B4: Moderate
Rarity	Common habitat in Hong Kong waters. No species of conservation importance was recorded.
Re-creatability	Not re-creatable
Fragmentation	Unfragmented
Ecological linkage	Generally linked with the open sea
Potential value	Low
Nursery/breeding ground	Not a favorable breeding/nursery ground.
Age	N.A.
Abundance/Richness of wildlife	B1: Moderate in abundance, but it was highly dominated by one opportunistic Polychaete species. B2-B4: Low in abundance.
Ecological value	Low

Intertidal Habitats

7.5.4 Intertidal habitats within the Assessment Area are considered to be of low ecological value due to the low fauna diversity recorded. No intertidal species of conservation importance was recorded.

Table 7.13 Evaluation of the Intertidal Habitat within the Assessment Area

Criteria	Intertidal Habitats
Naturalness	Low. The whole area is mainly composed of artificial sloping boulders and artificial vertical seawall.
Size	Medium. Hard shore covers a total length around 3.5 km.
Diversity	Low diversity epifauna community, supporting a range of common species – mainly gastropods.
Rarity	Common habitat in Hong Kong waters. No species of conservation importance was recorded.
Re-creatability	Can be recreated using boulder seawall.
Fragmentation	Unfragmented
Ecological Linkage	Ecological linkage was not observed.
Potential Value	Potential value is limited due to factors including narrow shore length and depth, and disturbance from nearby quarry activities.
Nursery / Breeding Ground	No special value as nursery/breeding ground was found.
Age	Around 20 years along the coast of HKIA; about seven years along the coast of HKBCF
Wildlife Abundance / Richness	High abundance of gastropods, but low species richness.
Ecological Value	Low

Marine Waters

7.5.5 Marine waters within the Assessment Area are considered to be of low ecological value due to the low fauna diversity recorded. No species of conservation importance was recorded.

Table 7.14 Evaluation of the Marine Waters within the Assessment Area

Criteria	Marine Waters
Naturalness	Natural
Size	NA
Diversity	Low
Rarity	Common habitat in Hong Kong waters.
Re-creatability	Re-creatable
Fragmentation	Fragmented from the open western water.
Ecological Linkage	Not functionally linked to dolphin movement corridor, while the closest dolphin hotspot, the BMP is located 1.5 km from the marine waters within Assessment Area
Potential Value	Low. Condition of coral colonies are limited by water quality.
Nursery / Breeding Ground	No special value as nursery/breeding ground was found.
Age	N/A
Wildlife Abundance / Richness	Low
Ecological Value	Low

Table 7.15 Species of Conservation Importance Recorded within the Assessment Area during the Previous and Recent Surveys

Species	Distribution in Hong Kong⁽¹⁾	Rarity and Protection Status⁽²⁾	Recorded Habitats
Species	Distribution in Hong Kong⁽¹⁾	Rarity and Protection Status⁽²⁾	Previous Study⁽³⁾	Recent Survey
Hard Coral
Balanophyllia sp.	Common	Cap. 586	Subtidal Hard Substrate Habitat	-
Oulastrea crispata	Common	Cap. 586	-	Subtidal Hard Substrate Habitat

Note:

1. Chan et al. (2005)

2. Cap. 586: Protection of Endangered Species of Animals and Plants Ordinance (Cap. 586).

3. HyD (2009a).

7.6 Impact Assessment and Evaluation

Construction Phase

7.6.1 According to the latest programme, the proposed works will tentatively commence in 2020 for completion in 2022. The Bonded Vehicular Bridge consists of a 5-span continuous deck viaduct with a total length of approximately 360 m mainly supported by 6 major piers.

7.6.2 As discussed in Section 2, the precast concrete construction method is preferred to the construction methods of cast in-place concrete and prefabricated steel structure. The preferred method does not require temporary steel platform or falsework, and thus no temporary habitat loss arising from the establishment of temporary work platform is anticipated. Since precast works are conducted away at a casting yard offsite while no open sea dredging is involved during precast concrete construction and marine bored piling, the extent and duration of construction activities required on-site could be minimised and hence the potential environmental impacts. No anti-corrosion paint is required for the precast concrete structures and thus the associated water quality impact is not anticipated.

7.6.3 Construction of the viaducts will generally involve the use of in-situ bored piles foundations founded on bedrock or seabed. All piling equipment would be set up on a barge after the installation of silt curtain, then the pile construction would be through the placing of steel pile casing at the pier site in which the seawater trapped inside the casing. A funnel would be placed at the top of pile casing during excavation. Mechanical Grab and Reverse Circulation Drill would be used for excavation of soil and rock socket respectively and then installing steel reinforcement fixing with permanent casing for concreting. No open sea dredging of seabed will be involved for the Bonded Vehicular Bridge construction. This construction method could also minimise the risk of disturbance to the seabed and the adjacent marine environment. The foundations and piers on top are located away from the existing sea walls which would not be disturbed during the bridge construction. The marine viaduct pile cap above high-tide level will be installed through construction of a cofferdam, which consists of using permanent precast panel. The seawater trapped inside the cofferdam would be pumped out to generate a dry working environment throughout the construction process. The bridge piers will be then construction by traditional means.

7.6.4 No open sea dredging will be involved for construction of the Bonded Vehicular Bridge. Silt curtain will be installed at first. It is expected that the installation of steel pile casing would only cause minor displacement of marine sediment, which will quickly settle without significant increase in suspended solids. Sediment excavation will only be carried out in a confined dry working environment. As mentioned in Section 6, the excavated marine-based sediments will be loaded onto the barge and transported to the designated disposal sites allocated by Marine Fill Committee (MFC). No barging points or conveyor systems will be established in the Project area.

Direct Impacts

Loss of Marine Habitats

7.6.5 The installation of steel pile casing (with diameter of 0.4 m) to create confined environment for excavation would lead to temporary loss of subtidal soft and hard bottom, and marine waters habitat, which are about 0.0087 ha in total. The casing would be removed upon the completion of construction works. Given the area affected is very small and scattered, the impact of temporary habitat loss is expected to be minor.

Direct Injury / Mortality of Wildlife

7.6.6 Under intensive ship traffic across Hong Kong waters, incidence of CWDs being injured and/or killed by vessel strike is occasional in Hong Kong (Parsons & Jefferson 2000). Further evidence from several stranded CWDs presented wounds consistent with blunt traumatic injury possibly caused by impacts from vessel bows or hulls during boat collisions. According to the results of photo identification monitoring by AFCD, several identified CWD individuals showed permanent injury marks on their bodies and fins caused by propellers. These indicate that vessel collision is a significant cause of death of local dolphins. Although vessel strike impact is not likely to be critical as most construction vessels for the transportation of precast units are large-sized and slow-moving, mitigation measure of ship speed control is recommended.

7.6.7 The construction of piers may cause potential direct impact on the corals located on boulder surface along REA2 which would be potentially impacted under the BVB and located close to the pier 1 within the Project area (refer to Figure 7.1) if unmitigated. Given the small colony size (6 to 25 cm), low coverage (<5%) and poor health conditions of the locally common species recorded at REA2 (Appendix 7.3 refers), direct impact of coral mortality is estimated to be minor. To further reduce direct impact on coral colonies, translocation as a precautionary measure is recommended for all 23 coral colonies albeit their poor health conditions before the commencement of the works. All the 23 gorgonian coral colonies (Guaiagorgia sp.) recorded at REA2 close to the bridge foundation works are technically feasible for translocation (refer to Appendix 7.3).

7.6.8 Provided that the marine habitats are evaluated as of low ecological value as stated in Section 7.5, while no rare species or marine species of conservation importance apart from corals was recorded within the Project footprint, the impact of direct loss of other wildlife is also anticipated to be minor.

Indirect Impacts

7.6.14 A total of 57 coral colonies (44 gorgonian coral Guaiagorgia sp. and 13 hard coral Oulastrea crispata) were found along REA1 and REA3 which are about 70 m and 190 m away from the Project site (refer to Figure 7.1). They are all locally common coral species with small colony size (from 3 to 25 cm) and low coverage (<5%), while most individuals are under poor health conditions (Appendix 7.3 refers). Since the affected habitat where the corals were recorded (i.e. subtidal hard substrate habitat) is of low ecological value (refer to Section 7.5.2 and Table 7.11), potential indirect impact on corals recorded at REA1 and REA3 is anticipated to be minor. According to Section 7.5, the ecological value of marine habitats within Assessment Area is evaluated as low. As no intertidal or benthic species of conservation importance is recorded within the Assessment Area, while the Assessment Area is unlikely to be the preferred habitat for CWDs in recent years, potential indirect impact on these marine species is predicted to be minor.

7.6.15 With the adoption of environmentally friendly construction method (i.e. precast concrete construction method, refer to Sections 5.7.2 and 5.7.3), proper implementation of site practices (e.g. the installation of silt curtain) and other water quality control measures (refer to Sections 5.9.1 to 5.9.20), adverse water quality impact on indirectly impacted coral colonies at REA1 and REA3, as well as on other marine wildlife (e.g. CWDs) due to the construction of marine bridge piles is estimated to be minor. As such, translocation of coral colonies recorded along REA1 and REA3 outside Project site is considered not necessary.

Operation Phase

Direct Impacts

Permanent Habitat Loss of Subtidal Soft and Hard Bottom

7.6.16 As the piles of the Bonded Vehicular Bridge (29 piles with diameter of 2 m) are located away from the sea walls, intertidal habitat will not be directly impacted during the bridge operation. There would be only permanent loss of approximately 0.009 ha subtidal soft and hard bottom habitats that are common in Hong Kong. Given the area affected is very small and scattered, the impact of habitat loss is expected to be minor.

Permanent Marine Waters Loss

7.6.17 Marine water loss accompanied with the loss of subtidal soft bottom habitat due to pier and foundation construction would result in the direct and permanent loss of CWD habitat. However, as Northeast Lantau waters including the footprint of Bonded Vehicular Bridge are not frequently used by the dolphins since 2015, while feeding and calving behaviour of CWDs were rarely recorded in Northeast Lantau waters during both AFCD monitoring programme and the monitoring surveys for HKBCF, HKLR and 3RS projects, the impact of marine habitat loss is anticipated to be minor and acceptable.

Indirect Impacts

Hydrological Change

7.6.18 Referring to Sections 5.7.14 to 5.7.17, changes in flow regime, momentary flow and accumulated flow, and thus flushing capacity are predicted to be insignificant. No adverse hydrodynamic impact on marine life would therefore be expected.

Disturbance to Aquatic and Marine Habitats and Wildlife

7.6.19 Road surface runoff containing small amount of grit might be discharged during operational phase. Chemical spillage from cleansing and maintenance of vehicles and traffic accident on the bridge is also possible. These may result in the pollution of marine waters and lead to lethal/sublethal effect on marine fauna by skin contact or ingestion. However, adverse impacts upon water quality on the remaining untranslocated corals, CWDs and other marine fauna would be minimal given sediment excavation would be carried out in a dry working environment (refer to Section 5.9.1), the establishment of a proper drainage system at planning and design stages, and the implementation of recommended mitigation measures and best management practices described in Sections 5.9.22 to 5.9.30.

7.6.20 Potential ecological impacts on the identified habitats within the ssessment Area associated with the construction and operation of the Project have been evaluated in accordance with the Annex 8 of the EIAO-TM, as presented in Table 7.16.

Criteria	Subtidal Hard Substrate Habitat	Subtidal Soft Bottom Habitat	Intertidal Habitat	Marine Waters
Habitat Quality	Low	Low	Low	Low
Species	One common hard coral (Oulastrea crispata) species of conservation importance was recorded.	No rare nor species of conservation importance recorded.	No rare nor species of conservation importance recorded.	The affected marine waters are not important habitat to CWD nor any marine species of conservation importance.
Size / Abundance	Permanent loss of about 0.009 ha and temporary loss of about 0.0087 ha of subtidal soft and hard bottom habitats due to the construction of bridge piles. Indirect impact due to water quality deterioration from marine works.	Permanent loss of about 0.009 ha and temporary loss of about 0.0087 ha of subtidal soft and hard bottom habitats due to the construction of bridge piles. Indirect impact due to water quality deterioration from marine works.	No direct impact is anticipated. Indirect impact due to water quality deterioration from marine works.	Permanent loss of about 0.009 ha and temporary loss of about 0.0087 ha of marine waters due to the construction of bridge piles. Indirect impact due to water quality deterioration from marine works.
Duration	Direct loss of subtidal and marine waters habitats due to the construction of bridge piles is permanent. Limited indirect impacts would be temporary during construction and operation phase.
Reversibility	Permanent loss of subtidal and marine waters habitats is not reversible. Indirect impacts would be reversible during construction and operation phases.
Magnitude	Low	Low	Low	Low
Overall Impact Evaluation	Low	Low	Low	Low

7.7 Cumulative impacts from Concurrent Projects

7.7.1 This section examines the possible interactions between the environmental impacts of the Project and those of other developments whose construction or operation phases would overlap with the Bonded Vehicular Bridge, thereby resulting in cumulative impacts whose synergistic effects would exceed in severity those of the various projects taken individually, and would likely to be wider in scope. Table 2.5 listed out all the concurrent projects during the construction and the operation phases of the Bonded Vehicular Bridge, and provided descriptions of these projects. Given the directly and indirectly affected areas are small and scattered, while the ecological values of impacted habitats are low (Table 7.16), the overall magnitude and severity of impact arising from the construction of Bonded Vehicular Bridge is regarded as low. Nearby projects that would have potential cumulative marine ecological impacts during the construction and operation phases of the Bonded Vehicular Bridge are summarised in Table 7.17 below. Major potential marine ecological cumulative impacts were described in Sections 7.7.2 to 7.7.8.

Table 7.17 Summary of Potential Concurrent Projects during Construction and Operation Phases

Proposed Development/ On-going Projects	Nature of the Projects	Major Potential Marine Ecological Impacts	Potential Cumulative Impact
Proposed Development/ On-going Projects	Nature of the Projects	Major Potential Marine Ecological Impacts	Construction	Operation
Expansion of Hong Kong International Airport into a Three-Runway System (3RS)	New land formation immediately north of HKIA comprising associated taxiways, aprons, new passenger concourse buildings and expansion of the existing Terminal 2 building	· Permanent loss of intertidal and subtidal hard bottom habitats of 5.9 km long for reclamation · Permanent loss of marine waters habitat of 650 ha in size for reclamation · Permanent loss of sub-tidal soft bottom habitats of 672 ha in size for reclamation	ü	ü
Tung Chung New Town Extension and its Associated Infrastructures (TCNTE)	New town development extension for accommodate 220,000 population to meet housing and other development needs	· Permanent loss of seabed and marine waters, 112 ha in size respectively · Potential water quality impact during construction phase	ü	ü
Tuen Mun – Chek Lap Kok Link (TMCLKL)	Dual-2 lane carriageway between northwest New Territories and HKBCF	· Temporary loss of seabed and marine waters of about 141 ha during construction · Permanent loss of seabed and marine waters respectively about 48 ha for marine piers and reclamation	-	ü
Hong Kong - Zhuhai - Macao Bridge Hong Kong Boundary Crossing Facilities (HKZMB HKBCF)	Boundary crossing facilities and serves as transfer point for road traffic between HKLR and TMCLKL	· Temporary loss of seabed and marine waters about 226ha during construction · Permanent loss of seabed about 138 ha for reclamation · Potential water quality impact during construction phase	-	ü
Planning, Engineering and Architectural Study for Topside Development at HKBCF Island of the HZMB – Feasibility Study	Study is under feasibility study stage and yet to be concluded. The construction programme is yet to be confirmed.	N/A	N/A	N/A
Hong Kong - Zhuhai - Macao Bridge Hong Kong Link Road (HKZMB HKLR) – Feasibility Study	Dual 3-lane carriageway connecting HKBCF	· Temporary loss of seabed and marine waters about 243 ha during construction phase · Permanent loss of seabed of around 30 ha for marine piers and reclamation · Potential water quality impact during construction phase	-	ü
North Commercial District	Development of a new commercial district on the northeast of HKIA	· Marine habitat loss is not anticipated	ü	-
Intermodal Transfer Terminal (ITT)	Development of a new building which serves intermodal transfer of passengers to and from HZMB	· Marine habitat loss is not anticipated	ü	-

Note:

“ü”= Potential cumulative impact is anticipated;

“-“ = Potential cumulative impact is not anticipated;

“N/A” = information not available

Permanent habitat loss

7.7.2 There would be cumulative marine habitat loss in North Lantau waters arising from the 3RS and TCNTE projects. The total permanent loss of marine habitats were estimated to be about 832 ha, while this Project will only contribute to less than 1 ha of marine habitat loss, and the affected habitat is evaluated as of low ecological value. With regard to the large area of cumulative marine habitat loss, the 3RS project recommended setting up approximately 2,400 ha of marine park area in addition to expanding the restricted access Hong Kong International Airport Approach Area (HKIAAA) zone by 118 ha to 729 ha. The establishment of marine park area would facilitate the conservation of remaining CWD habitat in Hong Kong waters and hence serve as a mitigation measure for the loss of CWD habitat arising from these projects. With these committed measures, the residual cumulative impacts to the CWD in terms of permanent habitat loss would be acceptable (AAHK, 2014).

7.7.3 It is considered the establishment of marine park of approximate 2,400 ha connecting the existing SCLKCMP, BMP, Pearl River Estuary CWD national nature reserve and the future extension of HKIAAA would also alleviate the cumulative impact of seabed and marine waters habitat loss on other marine wildlife. Therefore, the adverse residual impact of cumulative loss of marine habitats is anticipated to be acceptable (AAHK, 2014).

Acoustic Disturbance from Construction Works and Vessel Traffic

7.7.4 Construction vessels involved in the aforementioned projects and the construction of Bonded Vehicular Bridge would mostly be large-sized and slow-moving without the production of high energy or high frequency noises. Nevertheless, when intensive water construction activities occur, the sheer number and extent of vessel activity tends to inhibit use of the immediate areas by dolphins, probably due to decreased feeding efficiency, acoustic masking of communication and physical presence of vessels (Würsig et al. 2000). The cumulative impacts of marine activities in North Lantau waters on CWDs could be significant, especially if activities are staggered, such as the temporally overlapping construction of 3RS and the Bonded Vehicular Bridge, which could adversely affect calf production and survival, and thus an entire generation of CWDs.

7.7.5 Given that the number of vessels would increase significantly with these projects being constructed concurrently, cumulative impacts could occur but with the main component being from the 3RS project, while this Project would only contribute a maximum of four marine vessels (including flat barges and tug boats) per day during construction period. The 3RS project proposed to adopt mitigation in the form of acoustic decoupling of noisy equipment from the vessels to prevent transfer of noise into the marine environment, together with use of a dolphin exclusion zone during the marine works. These combined measures would be expected to reduce the magnitude of cumulative impacts of construction vessels to minor levels and further mitigation measures would not be required.

7.7.6 In terms of piling activities, all recent projects in Hong Kong have avoided the use of percussive piling which is known to potentially cause high impacts to the CWDs (Würsig et al. 2000). In addition, bored piling was adopted for the concurrent projects and is considered for this Project. The impact of cumulative underwater noise disturbance on CWDs is therefore predicted to be low.

Dolphin Injury / Mortality from Vessel Strike

7.7.7 As stated above, most construction vessels involved in concurrent projects and this Project are slow-moving, which allows CWDs to have sufficient time to avoid being injured or killed by the marine vessels. This Project would only involve the operation of a maximum of four marine vessels (including flat barges and tug boats) per day during construction period, while these marine vessels would manoeuvre around four times per day for material transport and construction means.

7.7.8 However, the number of construction vessels utilising the North Lantau waters would increase notably as a result of the concurrent projects, specifically for 3RS project which would be constructed in the vicinity of Bonded Vehicular Bridge. Both of these key projects, have proposed to adopt strict controls for their construction marine traffic, including speed limits of 10 knots within the works area and along defined vessel routes. The impact would be temporary and would last only during the cumulative period of construction works. Based upon this and the universal implementation of a similar level of mitigation, cumulative impacts could be reduced to acceptable levels.

7.8 Mitigation Measures and Precautionary Measures

7.8.1 Referring to Sections 7.5 and 7.6, as all identified marine ecological impacts are evaluated as of low severity and the affected marine habitats are of low ecological value, with proper project designs/ construction methods/ site practices, specific marine ecological mitigation measure is considered not necessary while precautionary measures are recommended as below.

Avoidance

7.8.2 The locations of foundations and piers of the proposed works were designed to be away from the seawalls, avoiding direct impacts on the intertidal habitats. Relatively eco-friendly construction methods (e.g. avoidance of dredging, use of bored piling and pile casing all as stated in Section 2.9.5) would be adopted to avoid encroachment on sites of conservation importance (e.g. the BMP).

Minimisation

Vessel Speed Limit Control

7.8.3 As ship strike is one of the major threats to CWDs, a speed limit of 10 knots should be strictly enforced on all construction-related vessels. The possibility of lethal injury to cetacean species is usually smaller than 5% when vessel speed is maintained at 10 knots or below (Vanderlaan and Taggart, 2007). This speed limit for vessels within the boundaries of the SCLKCMP appears to be effective in protecting CWDs from vessel collisions.

Minimising Water Quality Impact

7.8.4 No open sea dredging of seabed will be involved for the Bonded Vehicular Bridge construction. Marine bored piles involves the installation of a steel casing, excavation within the casing, concrete filling into the casing and then removing of casing. This construction method would minimise disturbance to the seabed and any significant deterioration of water quality.

7.8.5 Silt curtain should be deployed during the pile installation works to minimise any leakage of suspended solids or sediments into surrounding marine waters. Good site practice should be carried out to ensure the integrity and effectiveness of all silt curtains.

7.8.6 As detailed in the Water Quality Sections 5.9.1 to 5.9.20, good site practices, guidelines and mitigation measures should be adopted during the construction phase to minimise any potential water quality impacts, and therefore protecting marine ecological resources from indirect impacts.

7.8.7 Upon the completion of the construction works, the newly constructed rocky surface of foundations would provide extra suitable hard substrate habitats for marine fauna such as corals and barnacles to recolonise/re-establish.

Precautionary Measures

7.8.8 About 80 coral colonies (67 Guaiagorgia spp. and 13 Oulastrea crispata) were recorded along the three REA transects. They are all locally common coral species with small colony size (from 3 to 26 cm) and low coverage (<5%), while most individuals are under poor conditions (Appendix 7.3 refers). Since the affected habitat where the corals were recorded (i.e. subtidal hard substrate habitat) is of low ecological value, both direct and indirect marine ecological impacts on coral colonies are evaluated as of low severity.

7.8.9 As all 23 gorgonian corals colonies found along REA2 are technically feasible for translocation, translocation of these colonies is recommended as a precautionary measure. A detailed Coral Translocation Proposal, including description of methodology (e.g. pre-translocation survey, identification/ proposal of several suitable coral recipient site(s)) and post-translocation monitoring programme, should be prepared by the Project Proponent and subject to agreement with the authority before commencement of the coral translocation. All the pre-translocation survey, translocation exercises and post-translocation monitoring should be conducted by experienced marine ecologist(s) with at least 5 years relevant experience.

7.8.10 The recipient site of coral translocation should have the following characteristics:

· Marine conditions e.g. water depth, flow rate and temperature etc. are similar to the donor site;

· Presence of healthy coral colonies of the same species;

· Sufficient space available for the newly translocated coral; and

· Not to be impacted by construction works.

7.9 Residual Impacts

7.9.1 Residual impact would arise from the permanent loss of about 0.009 ha of subtidal soft and hard bottom habitats/ marine waters. The habitats of low ecological value is relatively small and support low diversity and density of wildlife, within which no rare species or species of conservation importance is recorded. The level of residual impact on the affected habitats is therefore considered to be minor and acceptable.

7.10 Environmental Monitoring and Audit Requirements

7.10.1 There will be a water quality monitoring programme during the construction phase of the project to ensure that all the recommended mitigation measures are properly implemented.

7.10.2 Precautionary post-translocation coral monitoring surveys would be conducted on translocated corals. The results of the post-translocation monitoring should be reviewed with reference to findings of the pre-translocation survey and the data from original colonies at the recipient site.

7.11 Conclusion

7.11.1 Marine habitats within the Assessment Area include subtidal hard substrate and soft bottom habitats, intertidal habitat and marine waters. Some locally common corals with small colony sizes, low coverage and relatively poor health conditions were recorded with Project area. The ecological values of the identified habitats are rated as low.

7.11.2 Relatively eco-friendly construction methods, such as the avoidance of dredging, use of bored piling and pile casing, would be adopted to avoid impact on sites and species of conservation importance. The proposed bridge marine section would unavoidably affect 0.009 ha subtidal hard and soft bottom habitats and marine waters, which have low ecological value. Pile precasting would also result in temporary loss of 0.0087 ha subtidal hard and soft bottom habitats and marine waters. Given the small size and low ecological values of the affected habitats without the presence of any rare species or marine species of conservation importance apart from some common corals, the impacts on marine wildlife (such as recorded coral and CWDs) are anticipated to be minor.

7.11.3 Based upon a precautionary approach, vessel speed limit of 10 knots should be strictly enforced within works area, and on construction vessels outside of the Assessment Area to avoid dolphin injury and/or death caused by vessel collision.

7.11.4 About 80 coral colonies (67 Guaiagorgia spp. and 13 Oulastrea crispata) were recorded along the three REA transects, while both direct and indirect marine ecological impacts on coral colonies are evaluated as of low severity. Direct impacts on the 23 coral colonies along REA2 located close to pier 1 within the Project Area could be further reduced by coral translocation as a precautionary measure. To minimise indirect impacts on the retained coral colonies recorded along REA1 (about 70m away from Project site) and REA3 (about 190 m away from Project site) and other marine fauna, further mitigation measures such as the deployment of silt curtain and other water quality control measures have been recommended.

7.12 Reference

Airport Authority Hong Kong (AAHK) (2014). Expansion of Hong Kong International Airport into a Three-Runway System – EIA Report.

Airport Authority Hong Kong (AAHK) (2018). Expansion of Hong Kong International Airport into a Three-Runway System – Construction Phase Monthly EM&A Report No.24.

Agriculture, Fisheries and Conservation Department (AFCD) (2002). Consultancy Study on Marine Benthic Communities in Hong Kong.

Agriculture, Fisheries and Conservation Department (AFCD) (2017). Monitoring of Marine Mammals in Hong Kong Waters (2016-17). Final Report (1 April 2016 to 31 March 2017).

Chan, A.L.K., Choi, C.L.S, McCorry, D., Chan, K.K., Lee, M.W., Ang, P. Jr. (2005). Field Guides to Hard Corals of Hong Kong. Agriculture, Fisheries and Conservation Department, Government of HKSAR.

Civil Engineering and Development Department (CEDD) (2015). Tung Chung New Town Extension – EIA Report.

DeVantier, L.M., G. De’ath, T.J. Done and Turak, E. (1998). Ecological Assessment of a Complex Natural System: A Case Study from the Great Barrier Reef. Ecological Applications 8:480-496.

EPD, 2006. 20 Years of Marine Water Quality Monitoring in Hong Kong 1986-2005. In: web site of Environmental Protection Department, HKSAR Government [Latest retrieved Oct 2016 from http://www.epd.gov.hk/epd/misc/marine_quality/1986-2005/index.html].

Hastings, M. C, and Popper, A. N. (2005). Effects of sound on fish. California Department of Transportation Contract 43A0139 Task Oder, 1.

Highways Department (HyD) (2009a). Hong Kong - Zhuhai - Macao Bridge Hong Kong Boundary Crossing Facilities – EIA Report.

Highways Department (HyD) (2009b). Hong Kong - Zhuhai - Macao Bridge Hong Kong Link Road – EIA Report.

Highways Department (HyD) (2009c). Tuen Mun – Chek Lap Kok Link – Investigation – EIA Report

Highways Department (HyD) (2009d). Tuen Mun – Chek Lap Kok Link – Investigation – EM&A Manual

Highways Department (HyD) (2018a). Hong Kong - Zhuhai - Macao Bridge Hong Kong Boundary Crossing Facilities – Monthly EM&A Report No. 37.

Highways Department (HyD) (2018b). Hong Kong - Zhuhai - Macao Bridge Hong Kong Link Road – Section between HKSAR Boundary and Scenic Hill – Monthly EM&A Report (Dec 2017).

Parsons, E. C. M. and T. A. Jefferson (2000). Post-mortem investigations on stranded dolphins and porpoises from Hong Kong waters. Journal of Wildlife Diseases 36:342-356.

Sims, P. Q., Hung, K. S. and Würsig, B. (2012). High-Speed Vessel Noises in West Hong Kong Waters and Their Contributions Relative to Indo-Pacific Humpback Dolphins (Sousa chinensis), Journal of Marine Biology, vol. 2012, Article ID 169103. doi:10.1155/2012/169103

Shin, P.K.S., Huang, Z.G., Wu, R.S.S., (2004). An updated baseline of subtropical macrobenthic communities in Hong Kong. Marine Pollution Bulletin 49, 119-141.

Vanderlaan, A .S M., and Taggart, C. T. (2007). Vessel collisions with whales: the probability of lethal injury based on vessel speed. Marine Mammal Science, 23(1), 144–156..

Würsig, B., Greene, J., C. R. and Jefferson, T.A. (2000). Development of an air bubble curtain to reduce underwater noise of percussive piling. Marine Environmental Research, 49, 79-93.

Table 7.1	Baseline Information of Ecological Resources in the Assessment Area
Table 7.2	Ecological Survey Schedule
Table 7.3	Physical Parameters of the Spot-Check Dive Locations
Table 7.4	Physical Parameters of the REA Transects
Table 7.5	Transects Ranking of Percentage Cover of Ecological and Substratum Attributes of the REA Transects
Table 7.6	Total Abundance and Biomass of Each Phylum
Table 7.7	Five Most Abundant Fauna at Each Sampling Site
Table 7.8	Number of Species, Abundance, Biomass, Species Diversity and Evenness at Each Sampling Site
Table 7.9	Mean Species Diversity (H’) and Species Evenness (J) of Benthic Communities at Different Waters
Table 7.10	Intertidal Species Recorded during the Walk-Through Survey
Table 7.11	Evaluation of the Subtidal Hard Substrate Habitat within the Assessment Area
Table 7.12	Evaluation of the Subtidal Soft Bottom Habitat within the Assessment Area
Table 7.13	Evaluation of the Intertidal Habitat within the Assessment Area
Table 7.14	Evaluation of the Marine Waters within the Assessment Area
Table 7.15	Species of Conservation Importance Recorded within the Assessment Area during the Previous and Recent Surveys
Table 7.16	Evaluation of Ecological Impacts on Marine Habitats within the Assessment Area
Table 7.17	Summary of Potential Concurrent Projects during Construction and Operation Phases

7 MARINE ECOLOGICAL IMPACT

Coral Survey

Benthos Survey

Intertidal Survey

Coral Colonies

Benthos

Intertidal Communities

Marine Mammals

Coral Colonies

Benthos

Intertidal Communities

Loss of Marine Habitats

Direct Injury / Mortality of Wildlife

Potential Disturbance to Recognised Sites of Conservation Importance

Noise Disturbance to Species of Conservation Importance

Disturbance Impacts on Aquatic and Marine Habitats and Wildlife

Permanent Habitat Loss of Subtidal Soft and Hard Bottom

Permanent Marine Waters Loss

Vessel Speed Limit Control

Minimising Water Quality Impact

Airport Authority Hong Kong (AAHK) (2014). Expansion of Hong Kong International Airport into a Three-Runway System – EIA Report.

Airport Authority Hong Kong (AAHK) (2018). Expansion of Hong Kong International Airport into a Three-Runway System – Construction Phase Monthly EM&A Report No.24.

Agriculture, Fisheries and Conservation Department (AFCD) (2002). Consultancy Study on Marine Benthic Communities in Hong Kong.

Agriculture, Fisheries and Conservation Department (AFCD) (2017). Monitoring of Marine Mammals in Hong Kong Waters (2016-17). Final Report (1 April 2016 to 31 March 2017).

Chan, A.L.K., Choi, C.L.S, McCorry, D., Chan, K.K., Lee, M.W., Ang, P. Jr. (2005). Field Guides to Hard Corals of Hong Kong. Agriculture, Fisheries and Conservation Department, Government of HKSAR.

Civil Engineering and Development Department (CEDD) (2015). Tung Chung New Town Extension – EIA Report.

DeVantier, L.M., G. De’ath, T.J. Done and Turak, E. (1998). Ecological Assessment of a Complex Natural System: A Case Study from the Great Barrier Reef. Ecological Applications 8:480-496.

EPD, 2006. 20 Years of Marine Water Quality Monitoring in Hong Kong 1986-2005. In: web site of Environmental Protection Department, HKSAR Government [Latest retrieved Oct 2016 from http://www.epd.gov.hk/epd/misc/marine_quality/1986-2005/index.html].

Hastings, M. C, and Popper, A. N. (2005). Effects of sound on fish. California Department of Transportation Contract 43A0139 Task Oder, 1.

Highways Department (HyD) (2009a). Hong Kong - Zhuhai - Macao Bridge Hong Kong Boundary Crossing Facilities – EIA Report.

Highways Department (HyD) (2009b). Hong Kong - Zhuhai - Macao Bridge Hong Kong Link Road – EIA Report.

Highways Department (HyD) (2009c). Tuen Mun – Chek Lap Kok Link – Investigation – EIA Report

Highways Department (HyD) (2009d). Tuen Mun – Chek Lap Kok Link – Investigation – EM&A Manual

Highways Department (HyD) (2018a). Hong Kong - Zhuhai - Macao Bridge Hong Kong Boundary Crossing Facilities – Monthly EM&A Report No. 37.

Highways Department (HyD) (2018b). Hong Kong - Zhuhai - Macao Bridge Hong Kong Link Road – Section between HKSAR Boundary and Scenic Hill – Monthly EM&A Report (Dec 2017).

Parsons, E. C. M. and T. A. Jefferson (2000). Post-mortem investigations on stranded dolphins and porpoises from Hong Kong waters. Journal of Wildlife Diseases 36:342-356.

Sims, P. Q., Hung, K. S. and Würsig, B. (2012). High-Speed Vessel Noises in West Hong Kong Waters and Their Contributions Relative to Indo-Pacific Humpback Dolphins (Sousa chinensis), Journal of Marine Biology, vol. 2012, Article ID 169103. doi:10.1155/2012/169103

Shin, P.K.S., Huang, Z.G., Wu, R.S.S., (2004). An updated baseline of subtropical macrobenthic communities in Hong Kong. Marine Pollution Bulletin 49, 119-141.

Vanderlaan, A .S M., and Taggart, C. T. (2007). Vessel collisions with whales: the probability of lethal injury based on vessel speed. Marine Mammal Science, 23(1), 144–156..