Environmental Complaint No.	Date of Complaint Received	Description of Environmental Complaints
COM-2017-108	23 February 2017 and 2 March 2017	Cleanliness problem at East Coast Road
COM-2017-112	27 March 2017	Noise and Water Quality
COM-2017-113	20 April 2017	Water quality problem at Portion X
COM-2017-095(3)	27 May 2017	Noise nuisance near Dragonair / CNAC (Group) Building (HKIA)

Description of Activities	Site Area
Stockpiling	WA7
Dismantling/trimming of temporary 40mm stone platform for construction of seawall	Portion X
Construction of seawall	Portion X
Loading and unloading of filling materials	Portion X
Construction of tunnel box structure at Scenic Hill Tunnel (Cut & Cover Tunnel)	Portion X
Backfilling at Scenic Hill Tunnel (Cut & Cover Tunnel)	Portion X
Excavation for HKBCF to Airport Tunnel & construction of tunnel box structure	Portion X
Excavation for diversion of culvert PR14	Portion X
Works for diversion	Airport Road
Utilities detection	Airport Road/ Airport Express Line/ East Coast Road
Establishment of site access	Airport Road/ Airport Express Line/ East Coast Road
Mined tunnel excavation/ box jacking underneath Airport Road and Airport Express Line	Airport Road and Airport Express Line
Construction of Tunnel box structure at Package T1.12.1	Near Kwo Lo Wan Road
Construction of Tunnel box structure	Shaft 3 Extension South & North Shaft
Excavation and lateral support works & Construction of Tunnel Box Structure for HKBCF to Airport Tunnel West (Cut & Cover Tunnel)	Airport Road
Excavation and lateral support works & construction of tunnel box structure for HKBCF to Airport Tunnel East (Cut & Cover Tunnel)	Portion X
Sub-structure & superstructure works for Highway Operation and Maintenance Area Building	Portion X
Superstructure works for Scenic Hill Tunnel West Portal Ventilation Building building	West Portal

Environmental Monitoring	Description	Monitoring Station	Frequencies	Remarks
Air Quality	1-hr TSP	AMS 5 & AMS 6	At least 3 times every 6 days	While the highest dust impact was expected.
24-hr TSP	At least once every 6 days	--
Noise	L_eq_(30mins)_, L₁₀_(30mins)and L₉₀_(30mins)	NMS5	At least once per week	Daytime on normal weekdays (0700-1900 hrs).
Water Quality	· Depth · Temperature · Salinity · Dissolved Oxygen (DO) · Suspended Solids (SS) · DO Saturation · Turbidity · pH	· Impact Stations: IS5, IS(Mf)6, IS7, IS8, IS(Mf)9 & IS10, · Control/Far Field Stations: CS2 & CS(Mf)5, · Sensitive Receiver Stations: SR3, SR4, SR5, SR10A & SR10B	Three times per week during mid-ebb and mid-flood tides (within ± 1.75 hour of the predicted time)	3 (1 m below water surface, mid-depth and 1 m above sea bed, except where the water depth is less than 6 m, in which case the mid-depth station may be omitted. Should the water depth be less than 3 m, only the mid-depth station will be monitored).
Dolphin	Line-transect Methods	Northeast Lantau survey area and Northwest Lantau survey area	Twice per month	--
Mudflat	Horseshoe crabs, seagrass beds, intertidal soft shore communities, sedimentation rates and water quality	San Tau and Tung Chung Bay	Once every 3 months	--

Parameter (unit)	Water Depth	Action Level	Limit Level
Dissolved Oxygen (mg/L)	Surface and Middle	5.0	4.2 except 5 for Fish Culture Zone
Bottom	4.7	3.6
Turbidity (NTU)	Depth average	27.5 or 120% of upstream control station’s turbidity at the same tide of the same day; The action level has been amended to “27.5 *and* 120% of upstream control station’s turbidity at the same tide of the same day” since 25 March 2013.	47.0 or 130% of turbidity at the upstream control station at the same tide of same day; The limit level has been amended to “47.0 *and* 130% of turbidity at the upstream control station at the same tide of same day” since 25 March 2013.
Suspended Solid (SS) (mg/L)	Depth average	23.5 or 120% of upstream control station’s SS at the same tide of the same day; The action level has been amended to “23.5 *and* 120% of upstream control station’s SS at the same tide of the same day” since 25 March 2013.	34.4 or 130% of SS at the upstream control station at the same tide of same day and 10mg/L for Water Services Department Seawater Intakes; The limit level has been amended to “34.4 *and* 130% of SS at the upstream control station at the same tide of same day and 10mg/L for Water Services Department Seawater Intakes” since 25 March 2013

3 Environmental Monitoring and Audit

3.1 Implementation of Environmental Measures

3.1.1 In response to the site audit findings, the Contractor have rectified all observations identified in environmental site inspections undertaken during the reporting period. Details of site audit findings and the corrective actions during the reporting period are presented in Appendix F.

3.1.2 A summary of the Implementation Schedule of Environmental Mitigation Measures (EMIS) is presented in Appendix E.

3.1.3 Regular marine travel route for marine vessels were implemented properly in accordance to the submitted plan and relevant records were kept properly.

3.1.4 Dolphin Watching Plan was implemented during the reporting period. No dolphins inside the silt curtain were observed. The relevant records were kept properly.

3.2 Air Quality Monitoring Results

3.2.1 The monitoring results for 1-hour TSP and 24-hour TSP are summarized in Tables 3.1 and 3.2 respectively. Detailed impact air quality monitoring results and relevant graphical plots are presented in Appendix G.

Table 3.1 Summary of 1-hour TSP Monitoring Results Obtained During the Reporting Period

Reporting Period	Monitoring Station	Average (mg/m³)	Range (mg/m³)	Action Level (mg/m³)	Limit Level (mg/m³)
March 2017	AMS5	87	35 – 249	352	500
March 2017	AMS6	109	59 – 225	360
April 2017	AMS5	54	16 – 106	352
April 2017	AMS6	72	32 – 126	360
May 2017	AMS5	140	9 – 719	352
May 2017	AMS6	124	7 – 569	360

Table 3.2 Summary of 24-hour TSP Monitoring Results Obtained During the Reporting Period

Reporting Period	Monitoring Station	Average (mg/m³)	Range (mg/m³)	Action Level (mg/m³)	Limit Level (mg/m³)
March 2017	AMS5	84	50 – 143	164	260
March 2017	AMS6	88	68 – 108	173
April 2017	AMS5	51	37 – 66	164
April 2017	AMS6	65	47 – 79	173
May 2017	AMS5	57	32 – 74	164
May 2017	AMS6	75	42 – 110	173

3.2.2 No Action Level exceedances of 1-hr TSP were recorded at AMS5 and no Action and Limit Level exceedances of 24-hr TSP were recorded at AMS5 and AMS6 during the reporting period.

3.2.3 On 10 May 2017, two Limit Level exceedances of 1-hr TSP level were recorded at AMS5 while two Action Level and one Limit Level exceedances of 1-hr TSP level were recorded at AMS6 during the reporting period. The Air Quality Health Index recorded by EPD at the Tung Chung station during the sampling period (8:00 to 16:00) ranged from 3 (low) to 10+ (serious). The general weather conditions in Tung Chung were sunny and haze with a low visibility during the sampling periods. The haze weather could cause higher readings of the portable dust meter. It was noted that the Contractor had implemented dust control measures throughout the construction phase. No fugitive dust emission was observed by ET on 10 May 2017 at construction site near monitoring stations AMS5 and AMS6. It was considered that the exceedances were not related to the construction activities of the Contract and were caused by the weather condition. In this case, no immediate actions are required. However, the Contractor is reminded to continuously implement the dust control measures throughout the construction phase. Record of notification of environmental quality limit exceedances are provided in Appendix M.

3.3 Noise Monitoring Results

3.3.1 The monitoring results for construction noise are summarized in Table 3.3 and the monitoring results and relevant graphical plots for this reporting period are provided in Appendix H.

Table 3.3 Summary of Construction Noise Monitoring Results Obtained During the Reporting Period

Reporting period	Monitoring Station	Average L_{eq (30 mins)}, dB(A)*	Range of L_{eq (30 mins)}, dB(A)*	Action Level	Limit Level L_{eq (30 mins)}, dB(A)
March 2017	NMS5	59	55 – 62	When one documented complaint is received	75
April 2017		64	59 – 73
May 2017		63	60 – 65

*A correction factor of +3dB(A) from free field to facade measurement was included.

3.3.2 No Action and Limit Level exceedances for noise were recorded during daytime on normal weekdays of the reporting period.

3.3.3 Major noise sources during the noise monitoring included construction activities of the Contract and nearby traffic noise and insect noise.

3.4 Water Quality Monitoring Results

3.4.1 Impact water quality monitoring was conducted at all designated monitoring stations during the reporting period. Impact water quality monitoring results and relevant graphical plots are provided in Appendix I.

3.4.2 An Action Level exceedance of suspended solid was recorded at station SR5 during mid-flood tide on 3 March 2017. Removal of surcharge and box culvert construction at Zones 1 and 2, drilling of pipe pile at Zone 1, seawall construction at Zones 2 and 3A, and transportation of fill material at Zone 3A were carried out within the properly deployed silt curtain as recommended in the EIA Report. There was no marine transportation at Zones 1, 2, and 3A. There were no specific activities recorded during the monitoring period that would cause any significant impacts on the monitoring results. No marine works was conducted near monitoring station SR5 which is located outside the site boundary of HKLR03 Contract. Also, there was no muddy plume observed at station SR5 during sampling exercise. No leakage of turbid water or any abnormity or malpractice for all contract works was observed during the sampling exercise.

3.4.3 Two Action Level exceedances of turbidity level were recorded at stations SR4 and IS8 on 24 March 2017. Also, an Action Level exceedance of suspended solid was recorded at station IS8 during mid-ebb tide and Three Limit Level exceedances of suspended solid were record at station SR4 during mid-ebb tide and at stations IS8 and SR4 during mid-flood tide on 24 March 2017. Removal of surcharge and box culvert construction at Zones 1 and 2, seawall construction at Zones 2 and 3A and transportation of fill material at Zone 3A were carried out within the properly deployed silt curtain as recommended in the EIA Report. Yellow-brown colour of water was observed at stations IS8 and SR4 during sampling exercise. However, there was no marine transportation at Zones 1, 2, and 3A and no marine works was conducted near monitoring stations SR4 and IS8 which are located outside the site boundary of HKLR03 Contract. There were no water quality exceedances at monitoring stations IS7 and IS(Mf)6 which are located closer to active work of the HKLR03 Contract than monitoring stations IS8 and SR4. No leakage of turbid water or any abnormity or malpractice for the contract works was observed during the sampling exercise.

3.4.4 On 27 March 2017, an Action Level exceedance of suspended solid was recorded at station IS8 during mid-ebb tide. Removal of surcharge and box culvert construction at Zones 1 and 2, seawall construction at Zones 2 and 3A and transportation of fill material at Zone 3A were carried out within the properly deployed silt curtain as recommended in the EIA Report. There was no marine transportation at Zones 1, 2, and 3A and no marine work was conducted near monitoring station IS8 which is located outside the site boundary of HKLR03 Contract. There were no specific activities recorded during the monitoring period that would cause any significant impacts on the monitoring results. Also, there was no muddy plume observed at station IS8 during sampling exercise. No leakage of turbid water or any abnormity or malpractice for the contract works was observed during the sampling exercise.

3.4.5 Record of “Notification of Environmental Quality Limit Exceedances” is provided in Appendix M.

3.4.6 Water quality impact sources during the water quality monitoring were the construction activities of the Contract, nearby construction activities by other parties and nearby operating vessels by other parties.

3.5 Dolphin Monitoring Results

Data Analysis

3.5.1 Distribution Analysis – The line-transect survey data was integrated with the Geographic Information System (GIS) in order to visualize and interpret different spatial and temporal patterns of dolphin distribution using sighting positions. Location data of dolphin groups were plotted on map layers of Hong Kong using a desktop GIS (ArcView^©3.1) to examine their distribution patterns in details. The dataset was also stratified into different subsets to examine distribution patterns of dolphin groups with different categories of group sizes, young calves and activities.

3.5.2 Encounter rate analysis – Encounter rates of Chinese white dolphins (number of on-effort sightings per 100 km of survey effort, and total number of dolphins sighted on-effort per 100 km of survey effort) were calculated in NEL and NWL survey areas in relation to the amount of survey effort conducted during each month of monitoring survey. Dolphin encounter rates were calculated in two ways for comparisons with the HZMB baseline monitoring results as well as to AFCD long-term marine mammal monitoring results.

3.5.3 Firstly, for the comparison with the HZMB baseline monitoring results, the encounter rates were calculated using primary survey effort alone, and only data collected under Beaufort 3 or below condition would be used for encounter rate analysis. The average encounter rate of sightings (STG) and average encounter rate of dolphins (ANI) were deduced based on the encounter rates from six events during the present quarter (i.e. six sets of line-transect surveys in North Lantau), which was also compared with the one deduced from the six events during the baseline period (i.e. six sets of line-transect surveys in North Lantau).

3.5.4 Secondly, the encounter rates were calculated using both primary and secondary survey effort collected under Beaufort 3 or below condition as in AFCD long-term monitoring study. The encounter rate of sightings and dolphins were deduced by dividing the total number of on-effort sightings (STG) and total number of dolphins (ANI) by the amount of survey effort for the present quarterly period.

3.5.5 Quantitative grid analysis on habitat use – To conduct quantitative grid analysis of habitat use, positions of on-effort sightings of Chinese White Dolphins collected during the quarterly impact phase monitoring period were plotted onto 1-km² grids among NWL and NEL survey areas on GIS. Sighting densities (number of on-effort sightings per km²) and dolphin densities (total number of dolphins from on-effort sightings per km²) were then calculated for each 1 km by 1 km grid with the aid of GIS. Sighting density grids and dolphin density grids were then further normalized with the amount of survey effort conducted within each grid. The total amount of survey effort spent on each grid was calculated by examining the survey coverage on each line-transect survey to determine how many times the grid was surveyed during the study period. For example, when the survey boat traversed through a specific grid 50 times, 50 units of survey effort were counted for that grid. With the amount of survey effort calculated for each grid, the sighting density and dolphin density of each grid were then normalized (i.e. divided by the unit of survey effort).

3.5.6 The newly-derived unit for sighting density was termed SPSE, representing the number of on-effort sightings per 100 units of survey effort. In addition, the derived unit for actual dolphin density was termed DPSE, representing the number of dolphins per 100 units of survey effort. Among the 1-km² grids that were partially covered by land, the percentage of sea area was calculated using GIS tools, and their SPSE and DPSE values were adjusted accordingly. The following formulae were used to estimate SPSE and DPSE in each 1-km² grid within the study area:

SPSE = ((S / E) x 100) / SA%

DPSE = ((D / E) x 100) / SA%

where S = total number of on-effort sightings

D = total number of dolphins from on-effort sightings

E = total number of units of survey effort

SA% = percentage of sea area

3.5.7 Behavioural analysis – When dolphins were sighted during vessel surveys, their behaviour was observed. Different activities were categorized (i.e. feeding, milling/resting, traveling, socializing) and recorded on sighting datasheets. This data was then input into a separate database with sighting information, which can be used to determine the distribution of behavioural data with a desktop GIS. Distribution of sightings of dolphins engaged in different activities and behaviours would then be plotted on GIS and carefully examined to identify important areas for different activities of the dolphins.

3.5.8 Ranging pattern analysis – Location data of individual dolphins that occurred during the 3-month baseline monitoring period were obtained from the dolphin sighting database and photo-identification catalogue. To deduce home ranges for individual dolphins using the fixed kernel methods, the program Animal Movement Analyst Extension, was loaded as an extension with ArcView^© 3.1 along with another extension Spatial Analyst 2.0. Using the fixed kernel method, the program calculated kernel density estimates based on all sighting positions, and provided an active interface to display kernel density plots. The kernel estimator then calculated and displayed the overall ranging area at 95% UD level.

Summary of Survey Effort and Dolphin Sightings

3.5.9 During the period of March to May 2017, six sets of systematic line-transect vessel surveys were conducted to cover all transect lines in NWL and NEL survey areas twice per month.

3.5.10 From these surveys, a total of 830.17 km of survey effort was collected, with 93.4% of the total survey effort being conducted under favourable weather conditions (i.e. Beaufort Sea State 3 or below with good visibility). Among the two areas, 333.83 km and 496.34 km of survey effort were conducted in NEL and NWL survey areas respectively.

3.5.11 The total survey effort conducted on primary lines was 583.29 km, while the effort on secondary lines was 246.88 km. Survey effort conducted on both primary and secondary lines were considered as on-effort survey data. A summary table of the survey effort is shown in Annex I of Appendix J.

3.5.12 During the six sets of monitoring surveys in March to May 2017, only four groups of 24 Chinese White Dolphins were sighted. A summary table of the dolphin sightings is shown in Annex II of Appendix J.

3.5.13 For the present quarterly period, all four dolphin sightings were made during on-effort search, while three of the four on-effort dolphin sightings were made on primary lines. In addition, all dolphin groups were sighted in NWL, and no dolphin was sighted at all in NEL. In fact, since August 2014, only two sightings of two lone dolphins were made respectively in NEL during HKLR03 monitoring surveys.

Distribution

3.5.14 Distribution of dolphin sightings made during monitoring surveys in March to May 2017 is shown in Figure 1 of Appendix J. Two of the dolphin sightings were made at the northwest corner of Lung Kwu Chau, while the other two sightings were located near Black Point and to the east of Sha Chau respectively (Figure 1 of Appendix J). On the other hand, the dolphins were completely absent from the central and eastern portions of North Lantau waters as in previous quarters (Figure 1 of Appendix J).

3.5.15 All dolphin sightings were located far away from the HKBCF and HKLR03 reclamation sites as well as along the alignments of HKLR09 and Tuen Mun-Chek Lap Kok Link (TMCLKL) (Figure 1 of Appendix J).

3.5.16 Sighting distribution of dolphins during the present impact phase monitoring period (March to May 2017) was drastically different from the one during the baseline monitoring period (Figure 1 of Appendix J). In the present quarter, dolphins have disappeared from the NEL region, which was in stark contrast to their frequent occurrence around the Brothers Islands, near Shum Shui Kok and in the vicinity of HKBCF reclamation site during the baseline period (Figure 1 of Appendix J). The nearly complete abandonment of NEL region by the dolphins has been consistently recorded in the past 16 quarters of HKLR03 monitoring, which has resulted in zero to extremely low dolphin encounter rates in this area.

3.5.17 In NWL survey area, dolphin occurrence was also significantly different between the baseline and impact phase periods. During the present impact monitoring period, only a handful of dolphin sightings were made in this survey area, which was in stark contrast with their frequent occurrences throughout the area during the baseline period (Figure 1 of Appendix J).

3.5.18 Another comparison in dolphin distribution was made between the five quarterly periods of spring months in 2013-17 (Figure 2 of Appendix J). Among the five spring periods, dolphins were regularly sighted in NWL waters in 2013 and 2014, but their usage there was dramatically reduced in the three subsequent spring periods, with the only occurrences mostly concentrated within and around the Sha Chau and Lung Kwu Chau Marine Park (Figure 2 of Appendix J).

Encounter Rate

3.5.19 During the present three-month study period, the encounter rates of Chinese White Dolphins deduced from the survey effort and on-effort sighting data from the primary transect lines under favourable conditions (Beaufort 3 or below) for each set of the surveys in NEL and NWL are shown in Table 3.4. The average encounter rates deduced from the six sets of surveys were also compared with the ones deduced from the baseline monitoring period (September – November 2011) (Table 3.5).

3.5.20 To facilitate the comparison with the AFCD long-term monitoring results, the encounter rates were also calculated for the present quarter using both primary and secondary survey effort. The encounter rates of sightings (STG) and dolphins (ANI) in NWL were 0.87 sightings and 5.23 dolphins per 100 km of survey effort respectively, while the encounter rates of sightings (STG) and dolphins (ANI) in NEL were both nil for this quarter.

Table 3.4 Dolphin Encounter Rates (Sightings Per 100 km of Survey Effort) During Reporting Period (March to May 2017)

Survey Area	Dolphin Monitoring	Encounter rate (STG) (no. of on-effort dolphin sightings per 100 km of survey effort)	Encounter rate (ANI) (no. of dolphins from all on-effort sightings per 100 km of survey effort)
Survey Area	Dolphin Monitoring	Primary Lines Only	Primary Lines Only
Northeast Lantau	Set 1 (2 & 7 Mar 2017)	0.00	0.00
	Set 2 (16 & 28 Mar 2017)	0.00	0.00
	Set 3 (12 & 20 Apr 2017)	0.00	0.00
	Set 4 (24 & 26 Apr 2017)	0.00	0.00
	Set 5 (18 & 22 May 2017)	0.00	0.00
	Set 6 (24 & 26 May 2017)	0.00	0.00
Northwest Lantau	Set 1 (2 & 7 Mar 2017)	0.00	0.00
	Set 2 (16 & 28 Mar 2017)	2.03	24.37
	Set 3 (12 & 20 Apr 2017)	1.71	3.41
	Set 4 (24 & 26 Apr 2017)	0.00	0.00
	Set 5 (18 & 22 May 2017)	1.85	3.70
	Set 6 (24 & 26 May 2017)	0.00	0.00

Table 3.5 Comparison of average dolphin encounter rates from impact monitoring period (March to May 2017) and baseline monitoring period (September – November 2011)

Survey Area	Encounter rate (STG) (no. of on-effort dolphin sightings per 100 km of survey effort)		Encounter rate (ANI) (no. of dolphins from all on-effort sightings per 100 km of survey effort)
Survey Area	Reporting Period	Baseline Monitoring Period	Reporting Period	Baseline Monitoring Period
Northeast Lantau	0.0	6.00 ± 5.05	0.0	22.19 ± 26.81
Northwest Lantau	0.93 ± 1.03	9.85 ± 5.85	5.25 ± 9.53	44.66 ± 29.85

Notes:
1) The encounter rates deduced from the baseline monitoring period have been recalculated based only on the survey effort and on-effort sighting data made along the primary transect lines under favourable conditions.

2) ± denotes the standard deviation of the average encounter rates.

3.5.21 In NEL, the average dolphin encounter rates (both STG and ANI) in the present three-month impact monitoring period were both zero with no on-effort sighting being made, and such extremely low occurrence of dolphins in NEL have been consistently recorded in the past 16 quarters of HKLR03 monitoring (Table 3.6). This is a serious concern as the dolphin occurrence in NEL in the past few years (0.0-1.0 for ER(STG) and 0.0-3.9 for ER(ANI)) have remained exceptionally low when compared to the baseline period (Table 3.6). Dolphins have been virtually absent from NEL waters since January 2014, with only three groups of six dolphins sighted there since then despite consistent and intensive survey effort being conducted in this survey area.

Table 3.6 Comparison of Average Dolphin Encounter Rates in Northeast Lantau Survey Area from All Quarters of Impact Monitoring Period and Baseline Monitoring Period (Sep – Nov 2011)

Monitoring Period	Encounter rate (STG) (no. of on-effort dolphin sightings per 100 km of survey effort)	Encounter rate (ANI) (no. of dolphins from all on-effort sightings per 100 km of survey effort)
September-November 2011 (Baseline)	6.00 ± 5.05	22.19 ± 26.81
December 2012-February 2013 (Impact)	3.14 ± 3.21	6.33 ± 8.64
March-May 2013 (Impact)	0.42 ± 1.03*	0.42 ± 1.03*
June-August 2013 (Impact)	0.88 ± 1.36	3.91 ± 8.36
September-November 2013 (Impact)	1.01 ± 1.59	3.77 ± 6.49
December 2013-February 2014 (Impact)	0.45 ± 1.10	1.34 ± 3.29
March-May 2014 (Impact)	0.00*	0.00*
June-August 2014 (Impact)	0.42 ± 1.04	1.69 ± 4.15
September-November 2014 (Impact)	0.00	0.00
December 2014-February 2015 (Impact)	0.00	0.00
March-May 2015 (Impact)	0.00*	0.00*
June-August 2015 (Impact)	0.44 ± 1.08	0.44 ± 1.08
September-November 2015 (Impact)	0.00	0.00
December 2015-February 2016 (Impact)	0.00	0.00
March-May 2016 (Impact)	0.00*	0.00*
June-August 2016 (Impact)	0.00	0.00
September-November 2016 (Impact)	0.00	0.00
December 2016-February 2017 (Impact)	0.00	0.00
March-May 2017 (Impact)	0.00*	0.00*

Notes:
1) The encounter rates deduced from the baseline monitoring period have been recalculated based only on survey effort and on-effort sighting data made along the primary transect lines under favourable conditions.

2) ± denotes the standard deviation of the average encounter rates.

3) The encounter rates in spring months were in blue and marked with asterisk.

3.5.22 On the other hand, the average dolphin encounter rates (STG and ANI) in NWL during the present impact phase monitoring period (reductions of 90.5% and 88.2% respectively) were only tiny fractions of the ones recorded during the three-month baseline period, indicating a dramatic decline in dolphin usage of this survey area as well during the present impact phase period (Table 3.7).

3.5.23 During the same spring quarters, dolphin encounter rates in NWL during spring 2017 was similar to the previous two spring periods, but was much lower than the ones in the spring periods of 2013 and 2014 (Table 3.7). Such temporal trend should be closely monitored in the upcoming monitoring quarters whether the dolphin occurrence would continue to increase as the construction activities of HZMB works have been mostly completed in coming months.

Table 3.7 Comparison of Average Dolphin Encounter Rates in Northwest Lantau Survey Area from All Quarters of Impact Monitoring Period and Baseline Monitoring Period (Sep – Nov 2011)

Monitoring Period	Encounter rate (STG) (no. of on-effort dolphin sightings per 100 km of survey effort)	Encounter rate (ANI) (no. of dolphins from all on-effort sightings per 100 km of survey effort)
September-November 2011 (Baseline)	9.85 ± 5.85	44.66 ± 29.85
December 2012-February 2013 (Impact)	8.36 ± 5.03	35.90 ± 23.10
March-May 2013 (Impact)	7.75 ± 3.96*	24.23 ± 18.05*
June-August 2013 (Impact)	6.56 ± 3.68	27.00 ± 18.71
September-November 2013 (Impact)	8.04 ± 1.10	32.48 ± 26.51
December 2013-February 2014 (Impact)	8.21 ± 2.21	32.58 ± 11.21
March-May 2014 (Impact)	6.51 ± 3.34*	19.14 ± 7.19*
June-August 2014 (Impact)	4.74 ± 3.84	17.52 ± 15.12
September-November 2014 (Impact)	5.10 ± 4.40	20.52 ± 15.10
December 2014-February 2015 (Impact)	2.91 ± 2.69	11.27 ± 15.19
March-May 2015 (Impact)	0.47 ± 0.73*	2.36 ± 4.07*
June-August 2015 (Impact)	2.53 ± 3.20	9.21 ± 11.57
September-November 2015 (Impact)	3.94 ± 1.57	21.05 ± 17.19
December 2015-February 2016 (Impact)	2.64 ± 1.52	10.98 ± 3.81
March-May 2016 (Impact)	0.98 ± 1.10*	4.78 ± 6.85*
June-August 2016 (Impact)	1.72 ± 2.17	7.48 ± 10.98
September-November 2016 (Impact)	2.86 ± 1.98	10.89 ± 10.98
December 2016-February 2017 (Impact)	3.80 ± 3.79	14.52 ± 17.21
March-May 2017 (Impact)	0.93 ± 1.03*	5.25 ± 9.53*

Notes:

1) The encounter rates deduced from the baseline monitoring period have been recalculated based only on survey effort and on-effort sighting data made along the primary transect lines under favourable conditions.

2) ± denotes the standard deviation of the average encounter rates.

3) The encounter rates in spring months were in blue and marked with asterisk.

3.5.24 As recently discussed in Hung (2016), the dramatic decline in dolphin usage of NEL waters in the past few years (including the declines in abundance, encounter rate and habitat use in NEL, as well as shifts of individual core areas and ranges away from NEL waters) was possibly related to the HZMB construction works that were commenced since 2012. Apparently such noticeable decline has already extended to NWL waters progressively in the past few years with no sign of recovery, even though the HZMB-related construction activities have well past the peak.

3.5.25 A two-way ANOVA with repeated measures and unequal sample size was conducted to examine whether there were any significant differences in the average encounter rates between the baseline and impact monitoring periods. The two variables that were examined included the two periods (baseline and impact phases) and two locations (NEL and NWL).

3.5.26 For the comparison between the baseline period and the present quarter (18^th quarter of the impact phase being assessed), the p-values for the differences in average dolphin encounter rates of STG and ANI were 0.0019 and 0.0186 respectively. If the alpha value is set at 0.05, significant differences were detected between the baseline and present quarters in both the average dolphin encounter rates of STG and ANI.

3.5.27 For the comparison between the baseline period and the cumulative quarters in impact phase (i.e. the first 18 quarters of the impact phase being assessed), the p-values for the differences in average dolphin encounter rates of STG and ANI were 0.000001 and 0.000000 respectively. Even if the alpha value is set at 0.00001, significant differences were still detected in both the average dolphin encounter rates of STG and ANI (i.e. between the two periods and the locations).

3.5.28 As indicated in both dolphin distribution patterns and encounter rates, dolphin usage has been significantly reduced in both NEL and NWL survey areas during the present quarterly period, and such low occurrence of dolphins has also been consistently documented in previous quarters of the past few years. This raises serious concern, as the timing of the decline in dolphin usage in North Lantau waters coincided well with the construction schedule of the HZMB-related projects (Hung 2016), and apparently there was no sign of recovery of dolphin usage even though most of the marine works associated with the HZMB construction have been completed.

Group Size

3.5.29 Group size of Chinese White Dolphins ranged from one to twelve individuals per group in North Lantau region during March to May 2017. The average dolphin group sizes from these three months were compared with the ones deduced from the baseline period in September to November 2011, as shown in Table 3.8.

Table 3.8 Comparison of Average Dolphin Group Sizes between Reporting Period (Mar 2017 – May 2017) and Baseline Monitoring Period (Sep – Nov 2011)

Survey Area	Average Dolphin Group Size
Survey Area	Reporting Period	Baseline Monitoring Period
Overall	6.00 ± 4.90 (n = 4)	3.72 ± 3.13 (n = 66)
Northeast Lantau	---	3.18 ± 2.16 (n = 17)
Northwest Lantau	6.00 ± 4.90 (n = 4)	3.92 ± 3.40 (n = 49)

Note:

1) ± denotes the standard deviation of the average group size.

3.5.30 The average dolphin group size in NWL waters during March to May 2017 was much higher than the one recorded during the three-month baseline period, but it could be partly related to the very small sample size of four groups when compared to the 66 groups sighted during the baseline period (Table 3.8). Two of these dolphin groups were composed of two individuals respectively, while the other two groups were large with eight and twelve individuals respectively (Annex II of Appendix J).

3.5.31 Distribution of the two large dolphin groups (i.e. five individuals or more per group) during the present quarter is shown in Figure 3 of Appendix J, with comparison to the one in baseline period. The group of eight individuals was sighted at the northwest corner of Lung Kwu Chau, whereas the group of 12 individuals was sighted to the east of Sha Chau (Figure 3 of Appendix J). Such distribution pattern was very different from the baseline period, when the larger dolphin groups were frequently sighted and evenly distributed in NWL waters, with a few also sighted in NEL waters (Figure 3 of Appendix J).

Habitat Use

3.5.32 From March to May 2017, the two grids with high dolphin densities were located at Lung Kwu Chau and Sha Chau, while the other two grids recorded low dolphin densities (Figures 4a and 4b of Appendix J). All grids near HKLR03/HKBCF reclamation sites as well as HKLR09/TMCLKL alignments did not record any presence of dolphins at all during on-effort search in the present quarterly period (Figures 4a and 4b of Appendix J).

3.5.33 However, it should be emphasized that the amount of survey effort collected in each grid during the three-month period was fairly low (6-12 units of survey effort for most grids), and therefore the habitat use pattern derived from the three-month dataset should be treated with caution. A more complete picture of dolphin habitat use pattern should be examined when more survey effort for each grid will be collected throughout the impact phase monitoring programme.

3.5.34 When compared with the habitat use patterns during the baseline period, dolphin usage in NEL and NWL has drastically diminished in both areas during the present impact monitoring period (Figure 5 of Appendix J). During the baseline period, many grids between Siu Mo To and Shum Shui Kok in NEL recorded moderately high to high dolphin densities, which was in stark contrast to the complete absence of dolphins there during the present impact phase period (Figure 5 of Appendix J).

3.5.35 The density patterns were also very different in NWL between the baseline and impact phase monitoring periods, with high dolphin usage throughout the area, especially around Sha Chau, near Black Point, to the west of the airport, as well as between Pillar Point and airport platform during the baseline period. In contrast, only two grids with high dolphin densities were located at Lung Kwu Chau and Sha Chau during the present impact phase period (Figure 5 of Appendix J).

Mother-calf Pairs

3.5.36 During the present quarterly period, no young calf was sighted at all among the four groups of dolphins.

Activities and Associations with Fishing Boats

3.5.37 Only one of the four groups was engaged in feeding activities, while none of them was engaged in socializing, traveling or milling/resting activity during the three-month study period.

3.5.38 The percentage of sightings associated with feeding activity (25.0%) was much higher than the one recorded during the baseline period (11.6%). However, it should be noted the sample size on total numbers of dolphin sightings during the present quarter (four dolphin groups) was much lower than the baseline period (66 dolphin groups).

3.5.39 Distribution of dolphins engaged in various activities during the present impact phase period and the baseline period is shown in Figure 6 of Appendix J. The only dolphin group engaged in feeding activity was sighted to the west of Sha Chau during the present quarterly period, which was very different from the baseline period when various dolphin activities occurred throughout the North Lantau region (Figure 6 of Appendix J).

3.5.40 Notably, one of the four dolphin groups was found to be associated with an operating purse-seiner during the present impact phase period.

Summary Photo-identification works

3.5.41 From March to May 2017, over 1,500 digital photographs of Chinese White Dolphins were taken during the impact phase monitoring surveys for the photo-identification work.

3.5.42 In total, 15 individuals sighted 19 times altogether were identified (see summary table in Annex III of Appendix J and photographs of identified individuals in Annex IV of Appendix J). All of these re-sightings were made in NWL. Two individuals (NL123 and NL286) were re-sighted twice, while one individual (NL202) was re-sighted thrice during the three-month period (Annex III of Appendix J).

3.5.43 Notably, two of these 15 individuals (NL226 and NL259) were also sighted in West Lantau waters during the HKLR09 monitoring surveys from March to May 2017, showing their extensive individual movements across different survey areas.

Individual range use

3.5.44 Ranging patterns of the 15 individuals identified during the three-month study period were determined by fixed kernel method, and are shown in Annex V of Appendix J.

3.5.45 All identified dolphins sighted in the present quarter were utilizing NWL waters only, but have completely avoided NEL waters where many of them have utilized as their core areas in the past (Annex V of Appendix J). This is in contrary to the extensive movements between NEL and NWL survey areas observed in the earlier impact monitoring quarters as well as the baseline period.

3.5.46 On the other hand, two individuals (NL226 and NL259) consistently utilized North Lantau waters in the past have extended their range use to WL during the present quarter. In the upcoming quarters, individual range use and movements should be continuously monitored to examine whether there has been any consistent shifts of individual home ranges from North Lantau to West or Southwest Lantau, as such shift could possibly be related to the HZMB-related construction works (see Hung 2015, 2016).

Action Level / Limit Level Exceedance

3.5.47 There was one Limit Level exceedance of dolphin monitoring for the quarterly monitoring data (between March 2017 – May 2017). According to the contractor’s information, the marine activities undertaken for HKLR03 during the quarter of March 2017 – May 2017 included removal of surcharge, road and drainage construction, seawall construction, box culvert construction, and transportation of fill material.

3.5.48 There is no evidence showing the current LL non-compliance directly related to the construction works of HKLR03 (where the amounts of working vessels for HKLR03 have been decreasing), although the generally increased amount of vessel traffic in NEL during the impact phase has been partly contributed by HKLR03 works since October 2012. It should also be noted that reclamation work under HKLR03 (adjoining the Airport Island) situates in waters which has rarely been used by dolphins in the past, and the working vessels under HKLR03 have been travelling from source to destination in accordance with the Marine Travel Route to minimize impacts on Chinese White Dolphin (CWD). In addition, the contractor will implement proactive mitigation measures such as avoiding anchoring at Marine Department’s designated anchorage site – Sham Shui Kok Anchorage (near Brothers Island) as far as practicable.

3.5.49 According to Monitoring of Chinese White Dolphins in Southwest Lantau Waters – Fourth Quarterly Report (December 2015 to February 2016) which is available on ENPO’s website, with their primary ranges centered in North and West Lantau waters, some individuals showed apparent range shifts or extensions to Southwest Lantau waters in 2015-16. For example, three individual dolphins (NL120, WL46 and WL221) indicated obvious shifts in their range use from NWL to West Lantau (WL) and Southwest Lantau (SWL) waters. Moreover, many individuals (e.g. NL212, NL260, WL200, SL55, WL232, WL237 and WL265) have extended their ranges from WL waters to SWL waters. It remains to be seen whether some of these individuals have permanently shifted their ranges away from their primary ranges in North Lantau, or begin to spend more times in SWL waters as part of their ranges.

3.5.50 ENPO updated that the Hong Kong-Zhuhai-Macao Bridge Authority (HZMBA) for the Mainland section of Hong Kong-Zhuhai-Macao Bridge (HZMB) has commenced an interim survey on fisheries resources and CWD in the Mainland waters. ENPO presented the preliminary findings of the HZMBA interim survey on CWD sighting and photo-identification works which provide solid evidence that some CWD that were previously more often sighted in HK waters have expanded their ranges into the Mainland waters, and some with reduced usage in HK waters. These preliminary data were mentioned in Monitoring of Chinese White Dolphins in Southwest Lantau Waters – Fourth Quarterly Report (December 2015 to February 2016) which is available on ENPO’s website.

3.5.51 A two-way ANOVA with repeated measures and unequal sample size was conducted to examine whether there were any significant differences in the average encounter rates between the baseline and impact monitoring periods. The two variables that were examined included the two periods (baseline and impact phases) and two locations (NEL and NWL).

3.5.52 For the comparison between the baseline period and the present quarter (18^th quarter of the impact phase being assessed), the p-values for the differences in average dolphin encounter rates of STG and ANI were 0.0019 and 0.0186 respectively. If the alpha value is set at 0.05, significant differences were detected between the baseline and present quarters in both the average dolphin encounter rates of STG and ANI.

3.5.53 For comparison between the baseline period and the cumulative quarters in impact phase (i.e. first eighteen quarters of the impact phase being assessed), the p-values for the differences in average dolphin encounter rates of STG and ANI were 0.000001 and 0.000000 respectively. Even if the alpha value is set at 0.00001, significant differences were still detected in both the average dolphin encounter rates of STG and ANI (i.e. between the two periods and the locations).

3.5.54 The AFCD monitoring data during March 2017 to May 2017 has been reviewed by the dolphin specialist. During the same quarter, no dolphin was sighted from 54.18 km of survey effort on primary lines in NEL, while four groups of 11 dolphins were sighted from 94.66 km of survey effort on primary lines in NWL. This review has confirmed that the low occurrence of dolphins reported by the HKLR03 monitoring surveys in spring 2017 in NEL and NWL survey area is accurate.

3.5.55 All dolphin protective measures are fully and properly implemented in accordance with the EM&A Manual. According to the Regular Marine Travel Route Plan, the travelling speed of vessels must not exceed 5 knots when crossing the edge of the marine park. The Contractor will continue to provide training for skippers to ensure that their working vessels travel from source to destination to minimize impacts on Chinese White Dolphin and avoid anchoring at Marine Department’s designated anchorage site - Sham Shui Kok Anchorage (near Brothers Island) as far as practicable. Also, it is recommended to complete the marine works of the Contract as soon as possible so as to reduce the overall duration of impacts and allow the dolphins population to recover as early as possible.

3.5.56 A meeting was held on 17 July 2017 with attendance of representative of ENPO, Resident Site Staff (RSS), Environmental Team (ET) and dolphin specialist for Contract Nos. HY/2010/02, HY/2011/03, HY/2012/07, HY/2012/08, and HY/2011/09. The discussion/ recommendation as recorded in the minutes of the meeting, which might be relevant to HKLR03 Contract are summarized below.

3.5.57 It was concluded that the HZMB works is one of the contributing factors affecting the dolphins. It was also concluded the contribution of impacts due to the HZMB works as a whole (or individual marine contracts) cannot be quantified nor separate from the other stress factors.

3.5.58 It was reminded that the ETs shall keep reviewing the implementation status of the dolphin related mitigation measures and remind the contractor to ensure the relevant measures were fully implemented.

3.5.59 It was recommended that the marine works of HZMB projects should be completed as soon as possible so as to reduce the overall duration of impacts and allow the dolphins population to recover as early as possible.

3.5.60 It was also recommended that the marine works footprint (e.g., reduce the size of peripheral silt curtain) and vessels for the marine works should be reduced as much as possible, and vessels idling / mooring in other part of the North Lantau shall be avoided whenever possible.

3.5.61 HyD updated that the draft map of the proposed BMP was gazetted in February 2016. HyD updated that the draft map of the proposed Brothers Marine Park (BMP) was gazetted in February 2016. ENPO updated that the BMP was approved by the Chief Executive in the Executive Council in August 2016. The ETs were reminded to update the BMP boundary in the Regular Marine Travel Route (RMTR) Plan. The BMP was designated on 30 December 2016. It was suggested that the protection measures (e.g. speed limit control) for the approved BMP shall be brought forward so as to provide a better habitat for dolphin recovery. It was noted that under the latest RMTR Plan, the contractors have committed to reduce the vessel speed in BMP.

3.5.62 The marine travel route will shift along the edge of Brother Marine Park as much as practical under the RMTR Plan. It was noted that even though marine vessels may moor within the mooring site of BMP, commercial activities including loading / unloading / transshipment are not allowed except a permit is obtained. The HZMB works vessels were recommended to avoid the BMP.

3.5.63 It was remined that starting from January 2016, HSF from the SkyPier will be re-routed north to the northern edged of the Sha Chau and Lung Kwu Chau Marine Park which currently has the highest density of CWD in the NWL. While the HSF will reduce speed to 15 knots, the associated disturbance may still affect CWD in the area. It was implied that the CWDs in the area shall be closely followed.

3.5.64 There was a discussion on exploring possible further mitigation measures, for example, controlling the underwater noise. It was noted that the EIA reports for the projects suggested several mitigation measures, all of which have been implemented.

3.6 Mudflat Monitoring Results

Sedimentation Rate Monitoring

3.6.1 The baseline sedimentation rate monitoring was in September 2012 and impact sedimentation rate monitoring was undertaken on 28 March 2017. The mudflat surface levels at the four established monitoring stations and the corresponding XYZ HK1980 GRID coordinates are presented in Table 3.9 and Table 3.10.

Table 3.9 Measured Mudflat Surface Level Results

	Baseline Monitoring (September 2012)			Impact Monitoring (March 2017)
Monitoring Station	Easting (m)	Northing (m)	Surface Level (mPD)	Easting (m)	Northing (m)	Surface Level (mPD)
S1	810291.160	816678.727	0.950	810291.163	816678.732	1.129
S2	810958.272	815831.531	0.864	810958.261	815831.516	0.992
S3	810716.585	815953.308	1.341	810716.590	815953.300	1.468
S4	811221.433	816151.381	0.931	811221.411	816151.399	1.118

Table 3.10 Comparison of Measurement

	Comparison of measurement			Remarks and Recommendation
Monitoring Station	Easting (m)	Northing (m)	Surface Level (mPD)	Remarks and Recommendation
S1	0.003	0.005	0.179	Level continuously increased
S2	-0.011	-0.015	0.128	Level continuously increased
S3	0.005	-0.008	0.127	Level continuously increased
S4	-0.022	0.018	0.187	Level continuously increased

3.6.2 This measurement result was generally and relatively higher than the baseline measurement at S1, S2, S3 and S4. The mudflat level is continuously increased.

Water Quality Monitoring

3.6.3 The mudflat monitoring covered water quality monitoring data. Reference was made to the water quality monitoring data of the representative water quality monitoring station (i.e. SR3) as in the EM&A Manual. The water quality monitoring location (SR3) is shown in Figure 2.1.

3.6.4 Impact water quality monitoring in San Tau (monitoring station SR3) was conducted in March 2017. The monitoring parameters included dissolved oxygen (DO), turbidity and suspended solids (SS).

3.6.5 The Impact monitoring result for SR3 were extracted and summarised below:

Table 3.11 Impact Water Quality Monitoring Results (Depth Average)

Date	Mid Ebb Tide			Mid Flood Tide
Date	DO (mg/L)	Turbidity (NTU)	SS (mg/L)	DO (mg/L)	Turbidity (NTU)	SS (mg/L)
1-Mar-17	7.75	9.55	14.75	7.69	8.50	10.65
3-Mar-17	7.80	8.45	16.15	7.72	8.65	18.05
6-Mar-17	7.73	4.25	5.75	7.76	3.70	3.20
8-Mar-17	7.58	3.70	6.65	7.75	4.30	5.95
10-Mar-17	7.66	6.00	10.15	7.60	5.45	11.60
13-Mar-17	7.39	10.30	20.90	7.44	11.60	21.45
15-Mar-17	7.56	10.50	17.10	7.38	9.95	19.85
17-Mar-17	7.53	9.25	17.75	7.44	9.35	19.10
20-Mar-17	7.59	6.15	9.95	7.53	7.60	8.60
22-Mar-17	7.47	3.40	9.50	7.77	4.50	7.40
24-Mar-17	7.58	5.15	8.45	7.86	5.10	8.30
27-Mar-17	7.48	6.75	10.90	7.20	6.00	8.10
29-Mar-17	7.14	10.50	13.40	7.28	8.80	10.20
31-Mar-17	See Remark 1	See Remark 1	See Remark 1	7.15	11.25	18.20
Average	7.56	7.23	12.42	7.54	7.48	12.19
Remark: 1) The water quality monitoring (WQM) on 31 March 2017 during mid-ebb tide was cancelled for safety reason as the thunderstorm signal was hoisted by Hong Kong Observatory and lightning was recorded at the WQM stations.

Mudflat Ecology Monitoring

Sampling Zone

3.6.6 In order to collect baseline information of mudflats in the study site, the study site was divided into three sampling zones (labeled as TC1, TC2, TC3) in Tung Chung Bay and one zone in San Tau (labeled as ST) (Figure 2.1 of Appendix O). The horizontal shoreline of sampling zones TC1, TC2, TC3 and ST were about 250 m, 300 m, 300 m and 250 m respectively (Figure 2.2 of Appendix O). Survey of horseshoe crabs, seagrass beds and intertidal communities were conducted in every sampling zone. The present survey was conducted in March 2017 (totally 5 sampling days between 3^rd and 14^th March 2017).

3.6.7 Since the field survey of Jun. 2016, increasing number of trashes and even big trashes (Figure 2.3 of Appendix O) were found in every sampling zone. It raised a concern about the solid waste dumping and current-driven waste issues in Tung Chung Wan. Respective measures (e.g. manual clean-up) should be implemented by responsible units.

Horseshoe Crabs

3.6.8 Active search method was conducted for horseshoe crab monitoring by two experienced surveyors in every sampling zone. During the search period, any accessible and potential area would be investigated for any horseshoe crab individuals within 2-3 hours of low tide period (tidal level below 1.2 m above Chart Datum (C.D.)). Once a horseshoe crab individual was found, the species was identified referencing to Li (2008). The prosomal width, inhabiting substratum and respective GPS coordinate were recorded. A photographic record was taken for future investigation. Any grouping behavior of individuals, if found, was recorded. The horseshoe crab surveys were conducted on 5^th (for TC1), 12^th (for TC2) and 14^th (for TC3 and ST) March 2017. The weather was generally warm on 5th March while it was windy on 12^th and 14^th March.

Seagrass Beds

3.6.9 Active search method was conducted for seagrass bed monitoring by two experienced surveyors in every sampling zone. During the search period, any accessible and potential area would be investigated for any seagrass beds within 2-3 hours of low tide period. Once seagrass bed was found, the species, estimated area, estimated coverage percentage and respective GPS coordinates were recorded. The seagrass beds surveys were conducted on 5^th (for TC1), 12^th (for TC2) and 14^th (for TC3 and ST) March 2017. The weather was generally warm on 5^th March while it was windy on 12^th and 14^th March.

Intertidal Soft Shore Communities

3.6.10 The intertidal soft shore community surveys were conducted in low tide period on 4^th (for ST), 5^th (for TC1), 11^th (for TC3) and 12^th (for TC2) March 2017. In every sampling zone, three 100m horizontal transect lines were laid at high tidal level (H: 2.0 m above C.D.), mid tidal level (M: 1.5 m above C.D.) and low tidal level (L: 1.0 m above C.D.). Along every horizontal transect line, ten random quadrats (0.5 m x 0.5 m) were placed.

3.6.11 Inside a quadrat, any visible epifauna were collected and were in-situ identified to the lowest practical taxonomical resolution. Whenever possible a hand core sample (10 cm internal diameter 20 cm depth) of sediments was collected in the quadrat. The core sample was gently washed through a sieve of mesh size 2.0 mm in-situ. Any visible infauna was collected and identified. Finally, the top 5 cm surface sediments were dug for visible infauna in the quadrat regardless of hand core sample was taken.

3.6.12 All collected fauna were released after recording except some tiny individuals that are too small to be identified on site. These tiny individuals were taken to laboratory for identification under dissecting microscope.

3.6.13 The taxonomic classification was conducted in accordance to the following references: Polychaetes: Fauchald (1977), Yang and Sun (1988); Arthropods: Dai and Yang (1991), Dong (1991); Mollusks: Chan and Caley (2003), Qi (2004).

Data Analysis

3.6.14 Data collected from direct search and core sampling was pooled in every quadrat for data analysis. Shannon-Weaver Diversity Index (H’) and Pielou’s Species Evenness (J) were calculated for every quadrat using the formulae below,

H’= -Σ ( Ni / N ) ln ( Ni / N ) (Shannon and Weaver, 1963)

J = H’ / ln S, (Pielou, 1966)

where S is the total number of species in the sample, N is the total number of individuals, and Ni is the number of individuals of the i^th species.

Mudflat Ecology Monitoring Results and Conclusion

Horseshoe Crabs

3.6.15 In the present survey, two species of horseshoe crab Carcinoscorpius rotundicauda (total 44 ind.) and Tachypleus tridentatus (total 16 ind.) were recorded. For one sight record, grouping of 2-8 individuals was observed at same locations with similar substratum (fine sand or soft mud). Photo records were shown in Figure 3.1 of Appendix O while the complete survey records were listed in Annex II of Appendix O.

3.6.16 Table 3.1 of Appendix O summarizes the survey results of horseshoe crab in present survey. For Carcinoscorpius rotundicauda, very few individuals were found in TC1 (4 ind.) and TC2 (1 ind., prosomal width 48.30 mm) only resulting in very low search record (0.3-1.0 ind. hr^-1 person^-1). The average body size was 48.98 mm (prosomal width ranged 29.62-65.76 mm) in TC1. Relatively more individuals were found in TC3 (16 ind.) and ST (23 ind.). The search record of TC3 was 2.7 ind. hr^-1 person^-1 with average body size 37.59 mm (prosomal width ranged 16.89-70.29 mm). The search record of ST was the higher (3.8 ind. hr^-1 person^-1) while the average body size was 47.08 mm (prosomal width ranged 27.98-107.04 mm).

3.6.17 For Tachypleus tridentatus, there were only 5 and 11 individuals in TC3 and ST respectively. For TC3, the search record was 0.8 ind. hr^-1 person^-1 while the average body size was 40.99 mm (prosomal width ranged 29.54-50.66 mm). For ST, the search record was higher (1.8 ind. hr^-1 person^-1) while the average body size was 51.05 mm (prosomal width ranged 28.95-81.94 mm).

3.6.18 In the previous survey of Mar. 2015, there was one important finding that a mating pair of Carcinoscorpius rotundicauda was found in ST (prosomal width: male 155.1 mm, female 138.2 mm) (Figure 3.2 of Appendix O). It indicated the importance of ST as a breeding ground of horseshoe crab. Moreover, two moults of Carcinoscorpius rotundicauda were found in TC1 with similar prosomal width 130-140 mm (Figure 3.2 of Appendix O). It reflected that a certain numbers of moderately sized individuals inhabited the sub-tidal habitat of Tung Chung Wan after its nursery period on soft shore. These individuals might move onto soft shore during high tide for foraging, moulting and breeding. Then it would return to sub-tidal habitat during ebb tide. Because the mating pair should be inhabiting sub-tidal habitat in most of the time. The record was excluded from the data analysis to avoid mixing up with juvenile population living on soft shore. In another previous survey of Jun. 2016, the records of the two big individuals of Carcinoscorpius rotundicauda (prosomal width 117.37 mm and 178.17 mm) in TC1 were excluded from data analysis according to the same principle.

3.6.19 No marked individual of horseshoe crab was recorded in present survey. Some marked individuals were found in previous surveys conducted in Sep. 2013, Mar. 2014 and Sep. 2014. All of them were released through a conservation programme conducted by Prof. Paul Shin (Department of Biology and Chemistry, The City University of Hong Kong (CityU)). It was a re-introduction trial of artificial bred horseshoe crab juvenile at selected sites. So that the horseshoe crabs population might be restored in the natural habitat. Through a personal conversation with Prof. Shin, about 100 individuals were released in the sampling zone ST on 20 June 2013. All of them were marked with color tape and internal chip detected by specific chip sensor. There should be second round of release between June and September 2014 since new marked individuals were found in the survey of September 2014.

3.6.20 The artificial bred individuals, if found, would be excluded from the results of present monitoring programme in order to reflect the changes of natural population. However, the mark on their prosoma might have been detached during moulting after a certain period of release. The artificially released individuals were no longer distinguishable from the natural population without the specific chip sensor. The survey data collected would possibly cover both natural population and artificially bred individuals.

Population difference among the sampling zones

3.6.21 Figures 3.3 and 3.4 of Appendix O show the changes of number of individuals, mean prosomal width and search record of horseshoe crabs Carcinoscorpius rotundicauda and Tachypleus tridentatus respectively in every sampling zone throughout the monitoring period.

3.6.22 For TC3 and ST, medium to high search records (i.e. number of individuals) of both species were always found in wet season (Jun. and Sep.). The search record of ST was higher from Sep. 2012 to Jun. 2014 while it was replaced by TC3 from Sep. 2014 to Jun. 2015. The search records were similar between two sampling zones from Sep. 2015 to Jun. 2016. In Sep. 2016, the search record of Carcinoscorpius rotundicauda in ST was much higher than TC3. In the present survey (Mar. 2017), the search records of both species were similar again between two sampling zones. It showed a natural variation of horseshoe crab population in these two zones due to weather condition and tidal effect during the survey.

3.6.23 For TC1, the search record was at low to medium level throughout the monitoring period. The change of Carcinoscorpius rotundicauda was relatively more variable than that of Tachypleus tridentatus. Relatively, the search record was very low in TC2 (2 ind. in Sep. 2013; 1 ind. in Mar., Jun., Sep. 2014, Mar. and Jun. 2015; 4 ind. in Sep. 2015; 6 ind. in Jun. 2016; 1 ind. in Sep. 2016 and Mar. 2017).

3.6.24 About the body size, larger individuals of Carcinoscorpius rotundicauda were usually found in ST and TC1 relative to those in TC3. For Tachypleus tridentatus, larger individuals were usually found in ST followed by TC3 and TC1.

3.6.25 Throughout the monitoring period, it was obvious that TC3 and ST (western shore of Tung Chung Wan) was an important nursery ground for horseshoe crab especially newly hatched individuals due to larger area of suitable substratum (fine sand or soft mud) and less human disturbance (far from urban district). Relatively, other sampling zones were not a suitable nursery ground especially TC2. Possible factors were less area of suitable substratum (especially TC1) and higher human disturbance (TC1 and TC2: close to urban district and easily accessible). In TC2, large daily salinity fluctuation was a possible factor either since it was flushed by two rivers under tidal inundation. The individuals inhabiting TC1 and TC2 were confined in small foraging area due to limited area of suitable substrata.

Seasonal variation of horseshoe crab population

3.6.26 Throughout the monitoring period conducted, the search record of horseshoe crab declined obviously during dry season especially December (Figures 3.3 and 3.4 of Appendix O). In Dec. 2012, 4 individuals of Carcinoscorpius rotundicauda and 12 individuals of Tachypleus tridentatus were found only. In Dec. 2013, no individual of horseshoe crab was found. In Dec. 2014, 2 individuals of Carcinoscorpius rotundicauda and 8 individuals of Tachypleus tridentatus were found only. In Dec. 2015, 2 individuals of Carcinoscorpius rotundicauda, 6 individuals of Tachypleus tridentatus and one newly hatched, unidentified individual were found only. The horseshoe crabs were inactive and burrowed in the sediments during cold weather (<15 ºC). Similar results of low search record in dry season were reported in a previous territory-wide survey of horseshoe crab. For example, the search records in Tung Chung Wan were 0.17 ind. hr^-1 person^-1 and 0.00 ind. hr^-1 person^-1 in wet season and dry season respectively (details see Li, 2008). Relatively the search records were much higher in Dec. 2016. There were totally 70 individuals of Carcinoscorpius rotundicauda and 24 individuals of Tachypleus tridentatus in TC3 and ST. Because the survey was arranged in early December while the weather was warm with sunlight (~22 ºC during dawn according to Hong Kong Observatory database, Chek Lap Kok station on 5 Dec). In contrast, there was no search record in TC1 and TC2 because the survey was conducted in mid-December with colder and cloudy weather (~20 ºC during dawn on 19 Dec). The horseshoe crab activity would decrease gradually with the colder climate. In present survey (Mar. 2017), there were only 44 individuals of Carcinoscorpius rotundicauda and 16 individuals of Tachypleus tridentatus recorded in Tung Chung Wan. All the surveys were conducted at night while the ambient temperature was still low. Hence majority of horseshoe crabs remained burrowing in sediments. Moreover, there was large scaled recruitment of filamentious algae covering significant area of intertidal mudflat in Tung Chung Wan (Figure 3.5 of Appendix O). The algal cover would reduce the successful rate of active searching.

3.6.27 From Sep. 2012 to Dec. 2013, Carcinoscorpius rotundicauda was a less common species relative to Tachypleus tridentatus. Only 4 individuals were ever recorded in ST in Dec. 2012. This species had ever been believed of very low density in ST hence the encounter rate was very low. Since Mar. 2014, it was found in all sampling zones with higher abundance in ST. Based on its average size (mean prosomal width 39.28-49.81 mm), it indicated that breeding and spawning of this species had occurred about 3 years ago along the coastline of Tung Chun Wan. However, these individuals were still small while their walking trails were inconspicuous. Hence there was no search record in previous sampling months. Since Mar. 2014, more individuals were recorded due to larger size and higher activity (i.e. more conspicuous walking trail).

3.6.28 For Tachypleus tridentatus, sharp increase of number of individuals was recorded in ST during the wet season of 2013 (from Mar. to Sep.). According to a personal conversation with Prof. Shin (CityU), his monitoring team had recorded similar increase of horseshoe crab population during wet season. It was believed that the suitable ambient temperature increased its conspicuousness. However similar pattern was not recorded in the following wet seasons. The number of individuals increased in Mar. and Jun. 2014 followed by a rapid decline in Sep. 2014. Then the number of individuals fluctuated slightly in TC3 and ST until Mar. 2017 (present survey). Apart from natural mortality, migration from nursery soft shore to subtidal habitat was another possible cause. Since the mean prosomal width of Tachypleus tridentatus continued to grow and reached about 50 mm since Mar. 2014. Then it varied slightly between 35-65 mm from Sep. 2014 to Mar. 2017. Most of the individuals might have reached a suitable size (e.g. prosomal width 50-60 mm) strong enough to forage in sub-tidal habitat. Recently, Carcinoscorpius rotundicauda was a more common horseshoe crab species in Tung Chung Wan. It was recorded in the four sampling zones while the majority located in TC3 and ST. Tachypleus tridentatus was a less common species while its distribution was confined in TC3 and ST only. Since TC3 and ST were regarded as important nursery ground for both horseshoe crab species, box plots of prosomal width of two horseshoe crab species were constructed to investigate the changes of population in details.

Box plot of horseshoe crab populations in TC3

3.6.29 Figure 3.6 of Appendix O shows the changes of prosomal width of Carcinoscorpius rotundicauda and Tachypleus tridentatus in TC3. As mentioned above, Carcinoscorpius rotundicauda was rarely found between Sep. 2012 and Dec. 2013 hence the data were lacking. In Mar 2014, the major size (50% of individual records between upper and lower quartile) ranged 40-60 mm while only few individuals were found. From Mar. 2014 to Mar. 2017 (present survey), the size of major population decreased and more small individuals were recorded after Mar. of every year. It indicated new rounds of successful breeding and spawning of Carcinoscorpius rotundicauda in TC3. It matched with the previous mating record in ST in Mar. 2015. Also, there were slight increasing trends of body size from Jun. to Mar. of next year since 2015. It indicated a stable growth of individuals. Focused on much larger individuals (circle dots above the box in the box plots), the size range was quite variable (prosomal width 60-90 mm) along the sampling months. It was yet to determine their size of migrating to sub-tidal habitat in TC3. Or larger individuals might migrate northward to ST gradually.

3.6.30 For Tachypleus tridentatus, the major size ranged 20-50 mm while the number of individuals fluctuated from Sep. 2012 to Jun. 2014. Then a slight but consistent growing trend was observed from Sep. 2014 to Jun. 2015. The prosomal width increased from 25-35 mm to 35-65 mm. As mentioned, the large individuals might have reached a suitable size for migrating from the nursery soft shore to subtidal habitat. It accounted for the declined population in TC3. From Mar. to Sep. 2016, slight increasing trend of major size was noticed again. From Dec. 2016 to Mar. 2017 (present survey), the major size decreased to 25-45 mm. Across the monitoring period, the maximum prosomal width of major population ranged 60-80 mm. It reflected individuals reaching this size would gradually migrate to sub-tidal habitats.

Box plot of horseshoe crab populations in ST

3.6.31 Figure 3.7 of Appendix O shows the changes of prosomal width of Carcinoscorpius rotundicauda and Tachypleus tridentatus in ST. As mentioned above, Carcinoscorpius rotundicauda was rarely found between Sep. 2012 and Dec. 2013 hence the data were lacking. From Mar. 2014 to Sep. 2016, the size of major population decreased and more small individuals (i.e. circle dots below the box in the box plots) were recorded after Jun. of every year. It indicated new round of successful spawning in ST. It matched with the previous mating record in ST in Mar. 2015. Also, there were slight increasing trends of body size from Sep. to Jun. from 2014 to 2016. It indicated a stable growth of individuals. Across the whole monitoring period, the maximum prosomal width (i.e. circle dots above the box in the box plots) usually ranged 70-80 mm except Mar. 2017 (present survey). It reflected individuals reaching this size would gradually migrate to sub-tidal habitats. In Mar. 2017, a large individual (prosomal width 107.04 mm) was recorded that was believed a sub-tidal inhabitant move to intertidal shore occasionally for foraging at night.

3.6.32 For Tachypleus tridentatus, a consistent growing trend was observed for the major population from Dec. 2012 to Dec. 2014 regardless of change of search record. The prosomal width increased from 15-30 mm to 55-70 mm. As mentioned, the large individuals might have reached a suitable size for migrating from the nursery soft shore to subtidal habitat. From Mar. to Sep. 2015, the size of major population decreased slightly to a prosomal width 40-60 mm. At the same time, the number of individuals decreased gradually. It further indicated some of large individuals might have migrated to sub-tidal habitat, leaving the smaller individuals on shore. There was an overall growth trend. In Dec. 2015, two big individuals (prosomal width 89.27 mm and 98.89 mm) were recorded only while it could not represent the major population. From Dec. 2015 to Mar. 2016, the number of individual was very few in ST that no boxplot could be produced. In Jun. 2016, the prosomal width of major population ranged 50-70 mm. But it dropped clearly to 30-40 mm in Sep. 2016 followed by an increase to 40-50 mm in Dec. 2016 and further to 40-70 mm in Mar. 2017 (present survey). Based on overall higher number of small individuals recorded in Jun. and Sep. 2016, it indicated new round of successful spawning in ST. Throughout the monitoring period, the maximum prosomal width of major population ranged 60-80 mm. It reflected individuals reaching this size would gradually migrate to sub-tidal habitats, similar to the finding in TC3.

3.6.33 As a summary for horseshoe crab populations in TC3 and ST, there was successful spawning of Carcinoscorpius rotundicauda from 2014 to 2016 while the spawning time should be in spring. There were consistent, increasing trends of population size in these two sampling zones. For Tachypleus tridentatus, small individuals were rarely found in TC3 and ST from 2014 to 2015. It was believed no occurrence of successful spawning. The existing individuals (that recorded since 2012) grew to a mature size and migrated to sub-tidal habitat. Hence the number of individuals decreased gradually. In 2016, new round of successful spawning was recorded in ST while increasing number of individuals and body size was noticed.

Impact of the HKLR project

3.6.34 It was the 18^th survey of the EM&A programme during the construction period. Based on the results, impact of the HKLR project could not be detected on horseshoe crabs. The population change was mainly determined by seasonal variation while successful spawnings were observed for both species. In case, abnormal phenomenon (e.g. very few numbers of horseshoe crab individuals in wet season, large number of dead individuals on the shore) is found, it would be reported as soon as possible.

Seagrass Beds

3.6.35 In the present survey, seagrass species Halophila ovalis and Zostera japonica were recorded in TC3 and ST. Photo records were shown in Figure 3.8 of Appendix O while the complete records of seagrass beds survey were shown in Annex III of Appendix O.

3.6.36 Table 3.2 of Appendix I summarizes the results of seagrass beds survey. In TC3, one small patch of Halophila ovalis was found in soft mud area at 0.5-1.0 m above C.D. while the total seagrass bed area and vegetation coverage were about 43.3 m² and 20% respectively.

3.6.37 In ST, four patches of Halophila ovalis were found while the total seagrass bed area was about 12437.5 m². The seagrass bed area was highly variable among patches. In the soft mud area at 0.5-1.5 m above C.D., the largest patch was an extensive, horizontal strand with area ~6521.9 m² and vegetation coverage 20%. It had covered significant portion of the mud flat area in ST. At vicinity, there was another extensive patch (3131.3 m², coverage 50%). At higher tidal level (1.5-2.0 m above C.D.), there were two seagrass patches in the sandy area nearby the seaward mangrove boundary. There were two horizontal strand, medium patches with area 1345.4-1438.9 m² and vegetation coverage 50%.

3.6.38 For Zostera japonica, there were two small patches only in the sandy area nearby the seaward mangrove boundary. The seagrass bed area and vegetation coverage were 4.1-76.4 m² and 50-100%.

3.6.39 Since majority of seagrass bed was confined in ST, the temporal change of both seagrass species was investigated in details.

Temporal variation of seagrass beds

3.6.40 Figure 3.9 of Appendix O shows the changes of estimated total area of seagrass beds in ST along the sampling months. For Zostera japonica, it was not recorded in the 1st and 2nd surveys of monitoring programme. Seasonal recruitment of few, small patches (total seagrass area: 10 m²) was found in Mar. 2013 that grew within the large patch of seagrass Halophila ovalis. Then the patch size increased and merged gradually with the warmer climate from Mar. to Jun. 2013 (15 m²). However, the patch size decreased and remained similar from Sep. 2013 (4 m²) to Mar. 2014 (3 m²). In Jun. 2014, the patch size increased obviously again (41 m²) with warmer climate followed by a decrease between Sep. 2014 (2 m²) and Dec. 2014 (5 m²). From Mar. to Jun. 2015, the patch size increased sharply again (90 m²). It might be due to the disappearance of the originally dominant seagrass Halophila ovalis resulting in less competition for substratum and nutrients. From Sep.2015 to Jun.2016, it was found coexisting with seagrass Halophila ovalis with steady increasing patch size (from 44 m² to 115 m²) and variable coverage. In Sep. 2016, the patch size decreased again to (38 m²) followed by an increase to a horizontal strand (80 m²) in Mar. 2017 (present survey). And it was no longer co-existing with Halophila ovalis. From Sep. 2014 to Mar. 2017, an increasing trend was noticed from Sep. to Jun. of next year followed by a rapid decline to Sep. It was possibly the causes of heat stress, typhoon and stronger grazing pressure during wet season.

3.6.41 For Halophila ovalis, it was recorded as 3-4 medium to large patches (area 18.9-251.7 m²; vegetation coverage 50-80%) beside the mangrove vegetation at tidal level 2 m above C.D. in Sep. 2012 (first survey). The total seagrass bed area grew steadily from 332.3 m² in Sep. 2012 to 727.4 m² in Dec. 2013. Flowers were observed in the largest patch during its flowering period. In Mar. 2014, 31 small to medium patches were newly recorded (variable area 1-72 m² per patch, vegetation coverage 40-80% per patch) in lower tidal zone between 1.0 and 1.5 m above C.D. The total seagrass area increased further to 1350 m². In Jun. 2014, these small and medium patches grew and extended to each other. These patches were no longer distinguishable and were covering a significant mudflat area of ST. It was generally grouped into 4 large patches (1116 – 2443 m²) of seagrass beds characterized of patchy distribution, variable vegetable coverage (40-80%) and smaller leaves. The total seagrass bed area increased sharply to 7629 m². In Sep. 2014, the total seagrass area declined sharply to 1111 m². There were only 3-4 small to large patches (6-253 m²) at high tidal level and 1 patch at low tidal level (786 m²). Typhoon or strong water current was a possible cause (Fong, 1998). In Sep. 2014, there were two tropical cyclone records in Hong Kong (7th-8th Sep.: no cyclone name, maximum signal number 1; 14th-17th Sep.: Kalmaegi, maximum signal number 8SE) before the seagrass survey dated 21st Sep. 2014. The strong water current caused by the cyclone, Kalmaegi especially, might have given damage to the seagrass beds. In addition, natural heat stress and grazing force were other possible causes reducing seagrass beds area. Besides, very small patches of Halophila ovalis could be found in other mud flat area in addition to the recorded patches. But it was hardly distinguished due to very low coverage (10-20%) and small leaves.

3.6.42 In Dec. 2014, all the seagrass patches of Halophila ovalis disappeared in ST. Figure 3.10 of Appendix O shows the difference of the original seagrass beds area nearby the mangrove vegetation at high tidal level between Jun. 2014 and Dec. 2014. Such rapid loss would not be seasonal phenomenon because the seagrass beds at higher tidal level (2.0 m above C.D.) were present and normal in December 2012 and 2013. According to Fong (1998), similar incident had occurred in ST in the past. The original seagrass area had declined significantly during the commencement of the construction and reclamation works for the international airport at Chek Lap Kok in 1992. The seagrass almost disappeared in 1995 and recovered gradually after the completion of reclamation works. Moreover, incident of rapid loss of seagrass area was also recorded in another intertidal mudflat in Lai Chi Wo in 1998 with unknown reason. Hence Halophila ovalis was regarded as a short-lived and r-strategy seagrass that could colonize areas in short period but disappears quickly under unfavorable conditions (Fong, 1998).

Unfavourable conditions to seagrass Halophila ovalis

3.6.43 Typhoon or strong water current was suggested as one unfavourable condition to Halophila ovalis (Fong, 1998). As mentioned above, there were two tropical cyclone records in Hong Kong in Sep. 2014. The strong water current caused by the cyclones might have given damage to the seagrass beds.

3.6.44 Prolonged light deprivation due to turbid water would be another unfavorable condition. Previous studies reported that Halophila ovalis had little tolerance to light deprivation. During experimental darkness, seagrass biomass declined rapidly after 3-6 days and seagrass died completely after 30 days. The rapid death might be due to shortage of available carbohydrate under limited photosynthesis or accumulation of phytotoxic end products of anaerobic respiration (details see Longstaff et al., 1999). Hence the seagrass bed of this species was susceptible to temporary light deprivation events such as flooding river runoff (Longstaff and Dennison, 1999).

3.6.45 In order to investigate any deterioration of water quality (e.g. more turbid) in ST, the water quality measurement results at two closest monitoring stations SR3 and IS5 of the EM&A programme were obtained from the water quality monitoring team. Based on the results from June to December 2014, the overall water quality was in normal fluctuation except there was one exceedance of suspended solids (SS) at both stations in September. On 10th Sep., 2014, the SS concentrations measured during mid-ebb tide at stations SR3 (27.5 mg/L) and IS5 (34.5 mg/L) exceeded the Action Level (≤23.5 mg/L and 120% of upstream control station’s reading) and Limit Level (≤34.4 mg/L and 130% of upstream control station’s reading) respectively. The turbidity readings at SR3 and IS5 reached 24.8-25.3 NTU and 22.3-22.5 NTU respectively. The temporary turbid water should not be caused by the runoff from upstream rivers. Because there was no rain or slight rain from 1^st to 10^th Sep. 2014 (daily total rainfall at the Hong Kong International Airport: 0-2.1 mm; extracted from the climatological data of Hong Kong Observatory). The effect of upstream runoff on water quality should be neglectable in that period. Moreover, the exceedance of water quality was considered unlikely to be related to the contract works of HKLR according to the ‘Notifications of Environmental Quality Limits Exceedances’ provided by the respective environmental team. The respective construction of seawall and stone column works, which possibly caused turbid water, were carried out within silt curtain as recommended in the EIA report. Moreover, there was no leakage of turbid water, abnormity or malpractice recorded during water sampling. In general, the exceedance of suspended solids concentration was considered to be attributed to other external factors, rather than the contract works.

3.6.46 Based on the weather condition and water quality results in ST, the co-occurrence of cyclone hit and turbid waters in Sep. 2014 might have combined the adverse effects on Halophila ovalis that leaded to disappearance of this short-lived and r-strategy seagrass species. Fortunately, Halophila ovalis was a fast-growing species (Vermaat et al., 1995). Previous studies showed that the seagrass bed could be recovered to the original sizes in 2 months through vegetative propagation after experimental clearance (Supanwanid, 1996). Moreover, it was reported to recover rapidly in less than 20 days after dugong herbivory (Nakaoka and Aioi, 1999). As mentioned, the disappeared seagrass in ST in 1995 could recover gradually after the completion of reclamation works for international airport (Fong, 1998). The seagrass beds of Halophila ovalis might recolonize the mudflat of ST through seed reproduction as long as there was no unfavorable condition in the coming months.

Recolonization of seagrass beds

3.6.47 Figure 3.10 of Appendix O shows the recolonization of seagrass bed area in ST from Dec. 2014 to Dec. 2016. From Mar. to Jun. 2015, 2-3 small patches of Halophila ovalis were newly found coinhabiting with another seagrass species Zostera japonica. But its total patch area was still very low relative to the previous records. The recolonization rate was low while cold weather and insufficient sunlight were possible factors between Dec. 2014 and Mar. 2015. Moreover, it would need to compete with seagrass Zostera japonica for substratum and nutrient. Since Zostera japonica had extended and had covered the original seagrass bed of Halophila ovalis at certain degree. From Jun. 2015 to Mar. 2016, the total seagrass area of Halophila ovalis had increased rapidly from 6.8 m² to 230.63 m². It had recolonized its original patch locations and covered Zostera japonica. In Jun. 2016, the total seagrass area increased sharply to 4707.3 m². Similar to the previous records of Mar to Jun. 2014, the original patch area increased further to a horizontally long strand. Another large seagrass beds colonized the lower tidal zone (1.0-1.5 m above C.D.). In Sep. 2016, this patch extended much and covered significant soft mud area of ST, resulting in sharp increase of total area (24245 m²). It indicated the second extensive colonization of this r-strategy seagrass. In Dec. 2016, this extensive seagrass patch decreased in size and had separated into few, undistinguishable patches. Moreover, the horizontal strand nearby the mangrove vegetation decreased in size (Figure 3.10 of Appendix O). The total seagrass bed decreased to 12550 m². In Mar. 2017 (present survey), the seagrass bed area remained stable (12438 m²) while the vegetation coverage decreased clearly (20-50%). Such decline of seagrass bed area might be similar to the record in Sep-Dec. 2014.

Impact of the HKLR project

3.6.48 It was the 18^th survey of the EM&A programme during the construction period. According to the results of present survey, there was clear recolonization of both seagrass species Halophila ovalis and Zostera japonica in ST. Hence the negative impact of HKLR project on the seagrass was not significant. From Dec. 2016 to Mar. 2017 (present survey), a decline of seagrass bed was noted again but it was yet to deduce the presence of stress factors. In case unfavorable phenomenon (e.g. reduction of seagrass patch size, abnormal change of leave color) is found persistent, it would be reported as soon as possible.

Intertidal Soft Shore Communities

3.6.49 Table 3.3 and Figure 3.11 of Appendix O show the types of substratum along the horizontal transect at every tidal level in all sampling zones. The relative distribution of different substrata was estimated by categorizing the substratum types (Gravels & Boulders / Sands / Soft mud) of the ten random quadrats along the horizontal transect. The distribution of substratum types varied among tidal levels and sampling zones:

Ÿ In TC1, high percentages of ‘Gravels and Boulders’ (80-90%) were recorded at all tidal levels. The minor substratum types were 'Sands' (10-20% at high and mid tidal levels) and 'Soft mud' (10% at low tidal level).

Ÿ In TC2, the major substratum types were ‘Sands’ (90% at high tidal level) and 'Soft mud' (60-80% at mid and low tidal levels). The minor substratum types were ‘Gravels and Boulders’ (30%) at mid tidal level and 'Sands' (20%) at low tidal level.

Ÿ In TC3, ‘Sands’ (50%) and 'Soft mud' (50%) were the usual substratum types at high tidal level. Higher percentage of ‘Sands’(70%) was recorded followed by 'Soft mud' (20%) at mid tidal level. At low tidal level, the major substratum type was ‘Gravels and Boulders’ (100%).

Ÿ In ST, high percentages of ‘Gravels and Boulders’ (80-100%) were recorded at high and mid tidal levels. At low tidal level, the major substratum type was ‘Soft mud’ (60%) followed by ' Gravels and Boulders’ (30%).

3.6.50 There was neither consistent vertical nor horizontal zonation pattern of substratum type in all sampling zones. Such heterogeneous variation should be caused by different hydrology (e.g. wave in different direction and intensity) received by the four sampling zones.

3.6.51 Table 3.4 of Appendix O lists the total abundance, density and number of taxon of every phylum in this survey. A total of 11451 individuals were recorded. Mollusca was clearly the most abundant phylum (total abundance 11153 ind., density 372 ind. m^-2, relative abundance 97.4%). The second and third abundant phyla were Arthropoda (182 ind., 6 ind. m^-2, 1.6%) and Annelida (61 ind., 2 ind. m^-2, 0.5%) respectively. Relatively other phyla were very low in abundances (density £1 ind. m^-2, relative abundance £0.2%). Moreover, the most diverse phylum was Mollusca (35 taxa) followed by Arthropoda (11 taxa) and Annelida (7 taxa). There were 1-2 taxa recorded only for other phyla. The taxonomic resolution and complete list of collected specimens are shown in Annexes IV and V of Appendix O respectively.

3.6.52 Table 3.5 of Appendix O shows the number of individual, relative abundance and density of each phylum in every sampling zone. The total abundance (1435-4154 ind.) varied among the four sampling zones while the phyla distributions were similar. In general, Mollusca was the most dominant phylum (no. of individuals: 1373-4074 ind.; relative abundance 95.7-98.1%; density 183-543 ind. m^-2). Other phyla were significantly lower in number of individuals. Arthropoda was the second abundant phylum (29-59 ind.; 1.2-2.2%; 4-8 ind. m^-2). Annelida was the third abundant phylum in TC1, TC2 and TC3 (14-27 ind.; 0.3-1.9%; 2-4 ind. m^-2) while Cnidaria (i.e. sea anemone) was the third abundant phylum in ST (12 ind.; 0.6%; 2 ind. m^-2). Relatively other phyla were low in abundance in all sampling zones (≤ 0.5%).

Dominant species in every sampling zone

3.6.53 Table 3.6 of Appendix O lists the abundant species (relative abundance >10%) in every sampling zone. In the present survey, most of the listed abundant species were of low to moderate densities (50-250 ind. m^-2). There was one dominant species of very high density (594 ind. m^-2) at certain tidal level in one sampling zone. Other listed species of lower density (< 50 ind. m^-2) were regared as common species.

3.6.54 In TC1, gastropod Batillaria multiformis was highly dominant at very high density (594 ind. m^-2, relative abundance 76%) at high tidal level (major substratum: ‘Gravels and Boulders’). At mid tidal level (major substratum: ‘Gravels and Boulders’), gastropods Batillaria multiformis (240 ind. m^-2, 49%), Monodonta labio (74 ind. m^-2, 15%) and rock oyster Saccostrea cucullata (78 ind. m^-2, 16%, attached on boulders) were abundant at low-moderate densities. At low tidal level (major substratum: ‘Gravels and Boulders’), rock oyster Saccostrea cucullata (117 ind. m^-2, 30%) was abundant at moderate density followed by gastropods Monodonta labio (82 ind. m^-2, 21%) and Batillaria multiformis (62 ind. m^-2, 16%).

3.6.55 In TC2, gastropods Cerithidea djadjariensis (265 ind. m^-2, 64%) was abundant at moderate densities at high tidal level (major substratum: 'Sands'). Gastropods Cerithidea cingulata (48 ind. m^-2, 12%) and Batillaria zonalis (41 ind. m^-2, 10%) were common species at high tidal level. There was no clearly abundant species at mid and low tidal levels. Rock oyster Saccostrea cucullata (5-38 ind. m^-2, 19-29%) and gastropod Batillaria zonalis (10-38 ind. m^-2, 29-38%) were common at mid and low tidal levels (major substratum: ‘Soft mud’). Besides gastropod Cerithidea djadjariensis (14 ind. m^-2, 11%) and polychaete Maldanidae spp. (4 ind. m^-2, 13%) were also common at mid and low tidal levels respectively.

3.6.56 In TC3, gastropods Cerithidea djadjariensis (238 ind. m^-2, 44%) and Batillaria multiformis (235 ind. m^-2, 43%) were abundant at moderate densities at high tidal level (major substrata: ‘Sands’ and 'Soft mud'). At mid tidal level (major substratum: ‘Sands’), gastropod Cerithidea djadjariensis (268 ind. m^-2, 57%) was abundant at moderate density followed by gastropods Batillaria multiformis (88 ind. m^-2, 19%) and Cerithidea cingulata (49 ind. m^-2, 10%). At low tidal level (major substratum: ‘Gravels and Boulders’), rock oyster Saccostrea cucullata (217 ind. m^-2, 41%) was the most abundant at moderate-high density followed by gastropod Monodonta labio (152 ind. m^-2, 29%).

3.6.57 In ST, gastropod Batillaria multiformis was abundant at moderate density (113 ind. m^-2, 33%) followed by Monodonta labio (66 ind. m^-2, 19%) and rock oyster Saccostrea cucullata (57 ind. m^-2, 17%) at high tidal level (major substratum: ‘Gravels and Boulders’). At mid tidal level (major substratum: ‘Gravels and Boulders’), rock oyster Saccostrea cucullata (124 ind. m^-2, 34%) was abundant at moderate density followed by common gastropods Monodonta labio (46 ind. m^-2, 13%) and Lunella coronata (42 ind. m^-2, 12%). No single species was abundant at low tidal level (major substratum: ‘Soft mud’). The common species were rock oyster Saccostrea cucullata (31 ind. m^-2, 29%) and gastropods Lunella coronata (16 ind. m^-2, 15%) and Batillaria zonalis (14 ind. m^-2, 13%).

3.6.58 In general, there was no consistent zonation pattern of species distribution across all sampling zones and tidal levels. The species distribution should be determined by the type of substratum primarily. In general, gastropods Batillaria multiformis (total number of individuals: 3531 ind., relative abundance 30.8%), Cerithidea djadjariensis (2326 ind., 20.3%), Cerithidea cingulata (447 ind., 3.9%) and Batillaria zonalis (423 ind., 3.7%) were the most commonly occurring species on sandy and soft mud substrata. Rock oyster Saccostrea cucullata (1760 ind., 15.4%), gastropods Monodonta labio (1178 ind., 10.3%) and Lunella coronata (396 ind., 3.5%) were commonly occurring species inhabiting gravel and boulders substratum.

Biodiversity and abundance of soft shore communities

3.6.59 Table 3.7 of Appendix O shows the mean values of species number, density, biodiversity index H’ and species evenness J of soft shore communities at every tidal level and in every sampling zone. As mentioned above, the differences among sampling zones and tidal levels were determined by the major type of substratum primarily.

3.6.60 Among the sampling zones, the mean species number of TC1 and ST (10-11 spp. 0.25 m^-2) were slightly higher than that of TC2 and TC3 (6-8 spp. 0.25 m^-2). The mean densities of TC1 and TC3 (513-554 ind. m^-2) were higher than TC2 and ST (191-269 ind. m^-2). Since the species distribution of ST was more even relatively, the mean H’ (1.6) and J (0.8) were higher than that of TC1, TC2 and TC3 (H': 1.1-1.4, J: 0.5-0.7).

3.6.61 Across the tidal levels, there was no consistent difference of the mean species number and H' in all sampling zones. For the mean density, there were generally decreasing trends in TC1, TC2 and ST from high to low tidal level. For the mean J, there was a slightly increasing trend from high to low tidal level in all sampling zones.

3.6.62 Figures 3.12 to 3.15 of Appendix O show the temporal changes of mean species number, mean density, H’ and J at every tidal level and in every sampling zone along the sampling months. In general, all the biological parameters fluctuated seasonally throughout the monitoring period. Lower mean species number and density were recorded in dry season (Dec.) but the mean H' and J fluctuated within a stable range.

3.6.63 Focusing on the changes of mean density in ST, there were decreasing trends regardless of tidal levels. It might be an unfavourable change that reflected environmental stresses. Since the total abundances might restore after spring. More consolidated statements would be made after the next wet season monitoring (Jun. 2017).

Impact of the HKLR project

3.6.64 It was the 18^th survey of the EM&A programme during the construction period. Based on the results, impacts of the HKLR project were not detected on intertidal soft shore community. As mentioned above, environmental stresses were yet to be confirmed based on the decreasing trends of mean density in ST. The coming wet season survey results were important. In case of other abnormal phenomena (e.g. rapid or consistent decline of fauna densities and species number) are observed, it would be reported as soon as possible.

3.7 Solid and Liquid Waste Management Status

3.7.1 The Contractor registered with EPD as a Chemical Waste Producer on 12 July 2012 for the Contract. Sufficient numbers of receptacles were available for general refuse collection and sorting.

3.7.2 The summary of waste flow table is detailed in Appendix K.

3.7.3 The Contractor was reminded that chemical waste containers should be properly treated and stored temporarily in designated chemical waste storage area on site in accordance with the Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes.

Monitoring Activity		Monitoring Date
Monitoring Activity		March 2017	April 2017	May 2017
Air Quality	1-hr TSP	1, 7, 13, 17, 23 and 29	3, 7, 13, 19, 25 and 28	4, 10, 16, 22 and 26
Air Quality	24-hr TSP	6, 10, 16, 22 and 28	1, 6, 12, 18, 24 and 27	2, 8, 13, 19, 25 and 31
Noise		1, 7, 13, 23 and 29	3, 13, 19 and 25	4, 10, 16 and 22
Water Quality		1, 3, 6, 8, 10, 13, 15, 17, 20, 22, 24, 27, 29 and 31	3, 5, 7, 10, 12, 14, 17, 19, 21, 24, 26 and 28	1, 3, 5, 8, 10, 12, 15, 17, 19, 22, 26, 29 and 31
Chinese White Dolphin		2, 7, 16 and 28	12, 20, 24 and 26	18, 22, 24 and 26
Mudflat Monitoring (Ecology)		3, 4, 10 and 14	--	--
Mudflat Monitoring (Sedimentation rate)		28	--	--
Site Inspection		8, 15, 22 and 31	5, 12, 19 and 28	4, 10, 17 and 26

	North Lantau Social Cluster
	NEL	NWL
Action Level	STG < 70% of baseline & ANI < 70% of baseline	STG < 70% of baseline & ANI < 70% of baseline
Limit Level	STG < 40% of baseline & ANI < 40% of baseline

	North Lantau Social Cluster
	NEL	NWL
Action Level	STG < 4.2 & ANI < 15.5	STG < 6.9 & ANI < 31.3
Limit Level	(STG < 2.4 & ANI < 8.9) and (STG < 3.9 & ANI < 17.9)

Environmental Monitoring	Parameters	Action Level (AL)	Limit Level (LL)
Air Quality	1-hr TSP	2	3
Air Quality	24-hr TSP	0	0
Noise	L_{eq (30 min)}	0	0
Water Quality	Suspended solids level (SS)	3	3
	Turbidity level	2	0
	Dissolved oxygen level (DO)	0	0
Dolphin Monitoring	Quarterly Analysis (Mar 2017 to May 2017)	0	1

1 Introduction

1.1.5 This is the nineteenth Quarterly Environmental Monitoring and Audit (EM&A) report for the Contract which summarizes the monitoring results and audit findings of the EM&A programme during the reporting period from 1 March 2017 to 31 May 2017.

1.2.1 The project organization structure and lines of communication with respect to the on-site environmental management structure with the key personnel contact names and numbers are shown in Appendix A.

1.3 Construction Programme

1.3.1 A copy of the Contractor’s construction programme is provided in Appendix B.

1.4 Construction Works Undertaken During the Reporting Period

1.4.1 A summary of the construction activities undertaken during this reporting period is shown in Table 1.1. The Works areas of the Contract are showed in Appendix C.

2.1 Summary of EM&A Requirements

2.1.1 The EM&A programme requires environmental monitoring of air quality, noise, water quality, dolphin monitoring and mudflat monitoring as specified in the approved EM&A Manual.

2.1.2 A summary of Impact EM&A requirements is presented in Table 2.1. The locations of air quality, noise and water quality monitoring stations are shown as in Figure 2.1. The transect line layout in Northwest and Northeast Lantau Survey Areas is presented in Figure 2.2.

2.2.1 Table 2.2 presents the Action and Limit Levels for the 1-hour TSP, 24-hour TSP and noise level.

2.2.2 The Action and Limit Levels for water quality monitoring are given as in Table 2.3.

2.2.3 The Action and Limit Levels for dolphin monitoring are shown in Tables 2.4 and 2.5.

2.3 Event Action Plans

2.3.1 The Event Actions Plans for air quality, noise, water quality and dolphin monitoring are annexed in Appendix D.

2.4 Mitigation Measures

2.4.1 Environmental mitigation measures for the contract were recommended in the approved EIA Report. Appendix E lists the recommended mitigation measures and the implementation status.

3 Environmental Monitoring and Audit

3.1 Implementation of Environmental Measures

3.1.1 In response to the site audit findings, the Contractor have rectified all observations identified in environmental site inspections undertaken during the reporting period. Details of site audit findings and the corrective actions during the reporting period are presented in Appendix F.

3.1.2 A summary of the Implementation Schedule of Environmental Mitigation Measures (EMIS) is presented in Appendix E.

3.1.3 Regular marine travel route for marine vessels were implemented properly in accordance to the submitted plan and relevant records were kept properly.

3.1.4 Dolphin Watching Plan was implemented during the reporting period. No dolphins inside the silt curtain were observed. The relevant records were kept properly.

3.2.1 The monitoring results for 1-hour TSP and 24-hour TSP are summarized in Tables 3.1 and 3.2 respectively. Detailed impact air quality monitoring results and relevant graphical plots are presented in Appendix G.

3.2.2 No Action Level exceedances of 1-hr TSP were recorded at AMS5 and no Action and Limit Level exceedances of 24-hr TSP were recorded at AMS5 and AMS6 during the reporting period.

3.3 Noise Monitoring Results

3.3.1 The monitoring results for construction noise are summarized in Table 3.3 and the monitoring results and relevant graphical plots for this reporting period are provided in Appendix H.

3.3.2 No Action and Limit Level exceedances for noise were recorded during daytime on normal weekdays of the reporting period.

3.3.3 Major noise sources during the noise monitoring included construction activities of the Contract and nearby traffic noise and insect noise.

3.4.1 Impact water quality monitoring was conducted at all designated monitoring stations during the reporting period. Impact water quality monitoring results and relevant graphical plots are provided in Appendix I.

3.4.5 Record of “Notification of Environmental Quality Limit Exceedances” is provided in Appendix M.

3.4.6 Water quality impact sources during the water quality monitoring were the construction activities of the Contract, nearby construction activities by other parties and nearby operating vessels by other parties.

Data Analysis

3.5.9 During the period of March to May 2017, six sets of systematic line-transect vessel surveys were conducted to cover all transect lines in NWL and NEL survey areas twice per month.

3.5.11 The total survey effort conducted on primary lines was 583.29 km, while the effort on secondary lines was 246.88 km. Survey effort conducted on both primary and secondary lines were considered as on-effort survey data. A summary table of the survey effort is shown in Annex I of Appendix J.

3.5.12 During the six sets of monitoring surveys in March to May 2017, only four groups of 24 Chinese White Dolphins were sighted. A summary table of the dolphin sightings is shown in Annex II of Appendix J.

Distribution

3.5.15 All dolphin sightings were located far away from the HKBCF and HKLR03 reclamation sites as well as along the alignments of HKLR09 and Tuen Mun-Chek Lap Kok Link (TMCLKL) (Figure 1 of Appendix J).

Encounter Rate

Group Size

Habitat Use

Mother-calf Pairs

3.5.36 During the present quarterly period, no young calf was sighted at all among the four groups of dolphins.

Activities and Associations with Fishing Boats

3.5.37 Only one of the four groups was engaged in feeding activities, while none of them was engaged in socializing, traveling or milling/resting activity during the three-month study period.

3.5.40 Notably, one of the four dolphin groups was found to be associated with an operating purse-seiner during the present impact phase period.

3.5.41 From March to May 2017, over 1,500 digital photographs of Chinese White Dolphins were taken during the impact phase monitoring surveys for the photo-identification work.

3.5.43 Notably, two of these 15 individuals (NL226 and NL259) were also sighted in West Lantau waters during the HKLR09 monitoring surveys from March to May 2017, showing their extensive individual movements across different survey areas.

Individual range use

3.5.44 Ranging patterns of the 15 individuals identified during the three-month study period were determined by fixed kernel method, and are shown in Annex V of Appendix J.

Action Level / Limit Level Exceedance

3.5.57 It was concluded that the HZMB works is one of the contributing factors affecting the dolphins. It was also concluded the contribution of impacts due to the HZMB works as a whole (or individual marine contracts) cannot be quantified nor separate from the other stress factors.

3.5.58 It was reminded that the ETs shall keep reviewing the implementation status of the dolphin related mitigation measures and remind the contractor to ensure the relevant measures were fully implemented.

3.5.59 It was recommended that the marine works of HZMB projects should be completed as soon as possible so as to reduce the overall duration of impacts and allow the dolphins population to recover as early as possible.

3.5.60 It was also recommended that the marine works footprint (e.g., reduce the size of peripheral silt curtain) and vessels for the marine works should be reduced as much as possible, and vessels idling / mooring in other part of the North Lantau shall be avoided whenever possible.

3.5.64 There was a discussion on exploring possible further mitigation measures, for example, controlling the underwater noise. It was noted that the EIA reports for the projects suggested several mitigation measures, all of which have been implemented.

3.6 Mudflat Monitoring Results

Sedimentation Rate Monitoring

3.6.2 This measurement result was generally and relatively higher than the baseline measurement at S1, S2, S3 and S4. The mudflat level is continuously increased.

Water Quality Monitoring

3.6.3 The mudflat monitoring covered water quality monitoring data. Reference was made to the water quality monitoring data of the representative water quality monitoring station (i.e. SR3) as in the EM&A Manual. The water quality monitoring location (SR3) is shown in Figure 2.1.

3.6.4 Impact water quality monitoring in San Tau (monitoring station SR3) was conducted in March 2017. The monitoring parameters included dissolved oxygen (DO), turbidity and suspended solids (SS).

3.6.5 The Impact monitoring result for SR3 were extracted and summarised below:

Sampling Zone

Horseshoe Crabs

Seagrass Beds

Intertidal Soft Shore Communities

3.6.12 All collected fauna were released after recording except some tiny individuals that are too small to be identified on site. These tiny individuals were taken to laboratory for identification under dissecting microscope.

3.6.13 The taxonomic classification was conducted in accordance to the following references: Polychaetes: Fauchald (1977), Yang and Sun (1988); Arthropods: Dai and Yang (1991), Dong (1991); Mollusks: Chan and Caley (2003), Qi (2004).

Data Analysis

3.6.14 Data collected from direct search and core sampling was pooled in every quadrat for data analysis. Shannon-Weaver Diversity Index (H’) and Pielou’s Species Evenness (J) were calculated for every quadrat using the formulae below,

Mudflat Ecology Monitoring Results and Conclusion

Horseshoe Crabs