Environmental Monitoring	Parameters	Action Level (AL)	Limit Level (LL)
Air Quality	1-hr TSP	0	0
24-hr TSP	0	0
Noise	L_eq_{(30 min)}	0	0
Water Quality	Suspended solids level (SS)	2	0
Turbidity level	0	0
Dissolved oxygen level (DO)	0	0
Dolphin Monitoring	Quarterly Analysis (Dec 2018 to Feb 2019 [KE1] )	0	1

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)	NMS 5	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(N), · Control/Far Field Stations: CS2(A) & CS(Mf)5, · Sensitive Receiver Stations: SR3(N), SR4(N), SR5(N), SR10A(N) & SR10B(N2)	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.

3.1.5 IEC informed ET and SOR through email on 25 February 2019 that two excavators working in the vicinity of shoreline interfacing with open waters at the southern end of Portion X of which one's with its bucket being immersed in the open waters without silt curtain being enclosed were observed at around 2:00 p.m. on 25 February 2019.

3.1.6 According to Contractor’s information, pure rock materials which were deposited on the existing seawall were retrieved using an excavator on 25 February 2019. As bucket of the excavator was immersed into the water, the work may relate to marine work. Silty water was not observed, according to the photos provided by IEC through email on 25 February 2019. It is noted that there are no exceedances for in-situ water data (dissolved oxygen, turbidity and suspended solid level) at stations IS5 and IS(Mf)6 which are the nearest monitoring stations for the concerned work area. During ET’s site inspection on 1 March 2019, silt curtains was placed around the concerned area. The Contractor was reminded to maintain silt curtains properly and enclose the concerned work area using silt curtains to avoid potential water quality impact.

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)
Dec 2018	AMS5	71	42 – 109	352	500
Dec 2018	AMS6	66	37 – 93	360
Jan 2019	AMS5	73	49 – 141	352
Jan 2019	AMS6	122	47 – 300	360
Feb 2019	AMS5	67	40 – 104	352
Feb 2019	AMS6	59	39 – 95	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)
Dec 2018	AMS5	53	36 – 83	164	260
Dec 2018	AMS6	62	41 – 83	173
Jan 2019	AMS5	69	49 – 94	164
Jan 2019	AMS6	81	56 – 110	173
Feb 2019	AMS5	53	31 – 77	164
Feb 2019	AMS6	56	29 – 84	173

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

3.2.3 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)
Dec 2018	NMS5	62	59 – 65	When one documented complaint is received	75
Jan 2019		58	57 – 59
Feb 2019		59	57 – 64

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

3.3.2 No Action/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 No Action and Limit Level exceedances of turbidity level and dissolved oxygen were recorded during reporting period. No Limit Level exceedance of suspended solids were recorded during the reporting period.

3.4.3 2 Action Level exceedances of suspended solids level were recorded during the reporting period. The exceedances of suspended solids level recorded during reporting period was considered to be attributed to other external factors such as sea condition, rather than the contract works. The exceedances were considered as non-contract related. Record of “Notification of Environmental Quality Limit Exceedances” is provided in Appendix M.

3.4.4 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(updated)

3.5.9 During the period of December 2018 to February 2019, 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 801.74 km of survey effort was collected, with 94.7% 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, 302.10 km and 499.64 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 579.99 km, while the effort on secondary lines was 221.75 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 Appendix J.

3.5.12 During the six sets of monitoring surveys conducted between December 2018 and February 2019, 12 groups of 38 Chinese White Dolphins were sighted, with the summary table of dolphin sightings shown in Annex II of Appendix J. Ten of the 12 dolphin sightings were made during on-effort search, with eight of the ten on-effort dolphin sightings being made on primary lines.

3.5.13 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 in NEL during HKLR03 monitoring surveys.

Distribution

3.5.14 Distribution of dolphin sightings made during HKLR03 monitoring surveys conducted from December 2018 to February 2019 is shown in Figure 1 of Appendix J. These sightings were all scattered at the western portion of the North Lantau region, with no particular concentration (Figure 1 of Appendix J).

3.5.15 As consistently recorded in previous monitoring quarters, the dolphins were completely absent from the central and eastern portions of North Lantau waters (Figure 1 of Appendix J). Moreover, all dolphin sightings were located far away from the HKLR03 and HKBCF reclamation sites as well as along the alignment of Tuen Mun-Chek Lap Kok Link (TMCLKL) (Figure 1 of Appendix J). However, two dolphin groups were sighted near the HKLR09 alignment to the west of Shum Wat.

3.5.16 Sighting distribution of dolphins during the present impact phase monitoring period (December 2018-February 2019) 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 occurrences 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 23 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 drastically different between the baseline and impact phase periods. During the present impact monitoring period, dolphins were seldom sighted here, and their distribution was restricted to the western portion of the North Lantau region, which was in stark contrast to 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 six quarterly periods of winter months in 2013-19. Among the six winter periods, dolphins were regularly sighted in NWL waters in 2013-14, but such usage was dramatically reduced in the five subsequent winter periods (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 2.15 sightings and 7.11 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 (December 2018 – February 2019)

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 (3 & 5 Dec 2018)	0.00	0.00
	Set 2 (10 & 12 Dec 2018)	0.00	0.00
	Set 3 (2 & 3 Jan 2019)	0.00	0.00
	Set 4 (7 & 14 Jan 2019)	0.00	0.00
	Set 5 (1 & 14 Feb 2019)	0.00	0.00
	Set 6 (20, 25 & 26 Feb 2019)	0.00	0.00
Northwest Lantau	Set 1 (3 & 5 Dec 2018)	3.95	11.86
	Set 2 (10 & 12 Dec 2018)	0.00	0.00
	Set 3 (2 & 3 Jan 2019)	3.32	14.94
	Set 4 (7 & 14 Jan 2019)	0.00	0.00
	Set 5 (1 & 14 Feb 2019)	3.86	7.72
	Set 6 (20, 25 & 26 Feb 2019)	3.29	13.16

Table 3.5 Comparison of average dolphin encounter rates from impact monitoring period (December 2018 – February 2019) 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	2.40 ± 1.88	9.85 ± 5.85	7.95 ± 6.60	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 23 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 August 2014, with only two lone dolphins sighted there on two separate occasions 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
June-August 2017 (Impact)	0.00	0.00
September-November 2017 (Impact)	0.00	0.00
December 2017-February 2018 (Impact)	0.00*	0.00*
March-May 2018 (Impact)	0.00	0.00
June-August 2018 (Impact)	0.00	0.00
September-November 2018 (Impact)	0.00	0.00
December 2018-February 2019 (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 winter 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 75.6% and 82.2% respectively) were only small 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).

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
June-August 2017 (Impact)	2.20 ± 2.88	6.58 ± 8.12
September-November 2017 (Impact)	3.12 ± 1.91	10.35 ± 9.66
December 2017-February 2018 (Impact)	4.75 ± 2.26*	15.73 ± 15.94*
March-May 2018 (Impact)	2.88 ± 4.81	11.12 ± 22.46
June-August 2018 (Impact)	1.16 ± 1.39	2.87 ± 3.32
September-November 2018 (Impact)	1.51 ± 2.25	2.70 ± 3.78
December 2018-February 2019 (Impact)	2.40 ± 1.88*	7.95 ± 6.60*

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 winter months were in blue and marked with asterisk.

3.5.23 Notably, when comparing the seven quarterly periods in winter months since 2013-14, the quarterly encounter rates in the winter of 2018-19 dropped to the lowest among all winter periods during the HKLR03 construction phase. The dramatic drop in dolphin occurrence should raise serious concerns, and such temporal trend should be closely monitored in the upcoming monitoring quarters as the construction activities of HZMB works will soon be completed in coming months.

3.5.24 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).

3.5.25 For the comparison between the baseline period and the present quarter (25^th quarter of the impact phase being assessed), the p-values for the differences in average dolphin encounter rates of STG and ANI were 0.0041 and 0.0221 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.

3.5.26 For the comparison between the baseline period and the cumulative quarters in impact phase (i.e. the first 25 quarters of the impact phase being assessed), the p-values for the differences in average dolphin encounter rates of STG and ANI were 0.000000 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).

3.5.27 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 when compared to the baseline period, and such low occurrence of dolphins has also been consistently documented in previous quarters of the past five years throughout the HZMB construction.

3.5.28 The significant decline in dolphin usage of North Lantau region 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 2018). Apparently there has been no sign of recovery of dolphin usage, even though almost all marine works associated with the HZMB construction have been completed, and the Brothers Marine Park has been established in late 2016 as a compensation measure for the permanent habitat loss in association with the HKBCF reclamation works.

Group Size

3.5.29 Group size of Chinese White Dolphins ranged from one to seven individuals per group in North Lantau region during December 2018 to February 2019. 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 (Dec 2018 – Feb 2019) and Baseline Monitoring Period (Sep – Nov 2011)

Survey Area	Average Dolphin Group Size
Survey Area	Reporting Period	Baseline Monitoring Period
Overall	3.17 ± 1.80 (n = 12)	3.72 ± 3.13 (n = 66)
Northeast Lantau	---	3.18 ± 2.16 (n = 17)
Northwest Lantau	3.17 ± 1.80 (n = 12)	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 December 2018 to February 2019 was lower than the one recorded during the three-month baseline period, but it should be noted that the sample size of 12 dolphin groups in the present quarter was only a small fraction of the sample size of 66 dolphin groups sighted during the baseline period (Table 3.8).

3.5.31 Notably, with the exception of three medium-sized groups with 5-7 animals, the other nine dolphin groups were small with 1-4 individuals per group only (Annex II of Appendix J).

3.5.32 Distribution of the larger dolphin groups with five animals or more per group during the present monitoring quarter is shown in (Figure 3 of Appendix J), with comparison to the one recorded during baseline period. The three medium-sized groups were located at the mouth of Deep Bay, near Lung Kwu Tan and between Sha Chau and Lung Kwu Chau respectively. This was drastically different from the baseline period, when the larger dolphin groups were frequently and evenly distributed in NWL waters, with a few also being sighted in NEL waters (Figure 3 of Appendix J).

Habitat Use

3.5.33 From December 2018 to February 2019, only nine grids in North Lantau waters recorded dolphin occurrences. The grids with moderately high dolphin densities were located near Lung Kwu Tan, between Sha Chau and Lung Kwu Chau, as well as to the north of the airport adjacent to the third runway expansion reclamation work site (Figures 4a and 4b of Appendix J). In contrast, the rest of the grids only recorded low to moderate DPSE values.

3.5.34 Notably, 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).

3.5.35 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 is collected throughout the impact phase monitoring programme.

3.5.36 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).

3.5.37 The density patterns were also drastically different in NWL between the baseline and impact phase monitoring periods, with high dolphin usage recorded throughout the area during the baseline period, especially around Sha Chau, near Black Point, to the west of the airport, as well as between Pillar Point and airport platform. In contrast, only several grids with moderate to high dolphin densities were scattered in the western portion of North Lantau waters during the present impact phase period (Figure 5 of Appendix J).

Mother-calf Pairs

3.5.38 During the present quarterly period, only one unspotted juvenile was sighted with its mother in the North Lantau region, and that was also the only young calf being sighted in the past two years of HKLR03 monitoring. The unspotted juvenile was spotted with its mother (WL145, a known individual from the photo-identification catalogue) at the southwest corner of NWL survey area, or adjacent to the HKLR09 alignment (Figure 6 of Appendix J).

3.5.39 The rare occurrence of young calves in the present quarter as well as in recent years was very different from their regular occurrence in North Lantau waters during the baseline period (Figure 6 of Appendix J). This should be of a serious concern, and the occurrence of young calves in North Lantau waters should be closely monitored in the upcoming quarters.

Activities and Associations with Fishing Boats

3.5.40 Two of the 12 dolphin groups were engaged in feeding activities, while none of them was engaged in socializing, traveling or milling/resting activity during the three-month study period.

3.5.41 The percentage of sightings associated with feeding activities (16.7%) was higher than the one recorded during the baseline period (11.6%). However, it should be noted the sample size on the total number of dolphin sightings during the present quarter (12 dolphin groups) was only a small fraction of the one during the baseline period (66 dolphin groups).

3.5.42 Distribution of dolphins engaged in various activities during the present impact phase period and the baseline period is shown in Figure 7 of Appendix J. The two dolphin groups engaged in feeding activities were sighted to the north of the airport platform and adjacent to the HKLR09 alignment respectively during the present quarterly period, which was very different from the baseline period when various dolphin activities occurred throughout the North Lantau region (Figure 7 of Appendix J).

3.5.43 Notably, none of the 12 dolphin groups was found to be associated with any operating fishing vessel during the present impact phase period.

Summary Photo-identification works

3.5.44 From December 2018 to February 2019, about 1,200 digital photographs of Chinese White Dolphins were taken during the impact phase monitoring surveys for the photo-identification work.

3.5.45 In total, 16 individuals sighted 31 times altogether were identified (see summary table in Appendix III and photographs of identified individuals in Appendix III of Appendix J and photographs of identified individuals in Appendix IV of Appendix J). All of these re-sightings were made in NWL. Five of the 16 individuals (i.e. CH34, NL123, NL136, NL182 and NL202) were re-sighted 3-4 times, while the other individuals were re-sighted only once or twice during the three-month monitoring period (Annex III of Appendix J).

3.5.46 Notably, only one of these individuals (NL259) was also sighted in WL waters during the HKLR09 monitoring surveys under the same three-month period.

Individual range use

3.5.47 Ranging patterns of the 16 individuals identified during the three-month study period were determined by fixed kernel method, and are shown in Annex V of Appendix J.

3.5.48 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.

3.5.49 On the other hand, in contrary to previous monitoring quarters, only one of the 16 individuals (NL259) have extended their range use to WL waters during the same winter quarter of 2018-19, while four individuals (i.e. WL98, WL243, WL273 and WL281) that consistently utilized WL waters in the past have extended their range use to NWL waters during the present quarter.

3.5.50 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 (and vice versa), as such shift could possibly be related to the HZMB-related construction works.

Action Level / Limit Level Exceedance

3.5.51 There was one Limit Level exceedance of dolphin monitoring for the quarterly monitoring data (between December 2018 – February 2019). According to the contractor’s information, the marine activities undertaken for HKLR03 during the quarter of December 2018 – February 2019 included seawall construction.

3.5.52 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 work area 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.

3.5.53 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.

3.5.54 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.

3.5.55 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).

3.5.56 For the comparison between the baseline period and the present quarter (25^thquarter of the impact phase being assessed), the p-values for the differences in average dolphin encounter rates of STG and ANI were 0.0041 and 0.0221 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.

3.5.57 For comparison between the baseline period and the cumulative quarters in impact phase (i.e. first 25 quarters of the impact phase being assessed), the p-values for the differences in average dolphin encounter rates of STG and ANI were 0.000000 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).

3.5.58 The AFCD monitoring data during December 2018 to February 2019 has been reviewed by the dolphin specialist. During the same quarter, no dolphin was sighted from 83.03 km of survey effort on primary lines in NEL, while only four groups of 14 dolphins were sighted from 127.29 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 winter 2018-19 in NEL and NWL survey area is accurate.

3.5.59 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 Brothers 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.

3.5.60 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.

3.5.61 The dolphin specialists of the projects confirmed that the CWD sighting around the North of Sha Chau and Lung Kwu Chau Marine Park (SCLKCMP) has significantly decreased, and it was likely related to the re-routing of high speed ferry (HSF) from Skypier.

3.5.62 ET will keep reviewing the implementation status of the dolphin related mitigation measures and remind the contractor to implement the relevant measures.

3.5.63 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.

3.5.64 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.

3.5.65 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.

3.5.66 The marine travel route will shift along the edge of the Brothers 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.

3.5.67 It was noted 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.

3.5.68 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 1 December 2018. 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 (December 2018)
Monitoring Station	Easting (m)	Northing (m)	Surface Level (mPD)	Easting (m)	Northing (m)	Surface Level (mPD)
S1	810291.160	816678.727	0.950	810291.177	816678.732	1.120
S2	810958.272	815831.531	0.864	810958.261	815831.516	0.974
S3	810716.585	815953.308	1.341	810716.572	815953.312	1.476
S4	811221.433	816151.381	0.931	811221.425	816151.415	1.121

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	0.017	0.005	0.170	Level continuously increased
S2	-0.011	-0.015	0.110	Level continuously increased
S3	-0.013	0.004	0.135	Level continuously increased
S4	-0.008	0.034	0.190	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(N)) as in the EM&A Manual. The water quality monitoring location (SR3(N)) is shown in Figure 2.1.

3.6.4 Impact water quality monitoring in San Tau (monitoring station SR3(N)) was conducted in December 2018. The monitoring parameters included dissolved oxygen (DO), turbidity and suspended solids (SS).

3.6.5 The Impact monitoring result for SR3(N) were extracted and summarised in Table 3.11:

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)
03-Dec-2018	6.8	4.4	7.1	6.7	11.8	13.2
05-Dec-2018	6.8	4.0	5.9	6.8	11.4	15.3
07-Dec-2018	6.7	3.4	6.4	6.9	2.3	6.4
10-Dec-2018	7.2	3.6	5.7	6.6	5.2	11.0
12-Dec-2018	7.1	5.5	9.1	7.5	7.3	12.3
14-Dec-2018	6.7	2.6	5.0	7.4	5.7	10.4
17-Dec-2018	7.6	2.1	3.0	7.2	2.4	4.2
19-Dec-2018	7.4	3.4	4.4	7.2	3.9	7.0
21-Dec-2018	7.1	2.6	5.8	6.7	4.2	7.4
24-Dec-2018	7.2	4.8	8.6	7.3	3.6	6.4
26-Dec-2018	6.7	5.7	7.5	6.9	3.7	7.5
28-Dec-2018	6.8	5.4	7.5	7.1	7.5	8.6
31-Dec-2018	7.7	2.7	5.2	7.6	6.1	8.8
Average	7.1	3.8	6.2	7.1	5.8	9.1

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 December 2018 (totally 5 sampling days between 1^st and 16^th December 2018).

3.6.7 Since the field survey of Jun. 2016, increasing number of trashes and even big trashes 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 government agency 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 1^st (for TC3), 2^nd (for TC1), 11^th (for ST) and 15^th (for TC2) December 2018. The weather was warm and sunny on first two survey days (1^st and 2^nd Dec.) while it was cold and cloudy on the following days (11^th and 15^th Dec).

3.6.9 In Jun. 2017, a big horseshoe crab was tangled by a trash gill net in ST mudflat (Figure 2.3 of Appendix O). It was released to sea once after photo recording. The horseshoe crab of such size should be inhabiting sub-tidal environment while it forages on intertidal shore occasionally during high tide period. If it is tangled by the trash net for few days, it may die due to starvation or overheat during low tide period. These trash gill nets are definitely ‘fatal trap’ for the horseshoe crabs and other marine life. Manual clean-up should be implemented as soon as possible by responsible government agency units.

Seagrass Beds

3.6.10 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 1^st (for TC3), 2^nd (for TC1), 11^th (for ST) and 15^th (for TC2) December 2018. The weather was warm and sunny on first two survey days (1^st and 2^nd Dec.) while it was cold and cloudy on the following days (11^th and 15^th Dec.).

Intertidal Soft Shore Communities

3.6.11 The intertidal soft shore community surveys were conducted in low tide period on 1^st (for TC3), 2^nd (for TC1), 15^th (for TC2) and 16^th (for ST) December 2018. In every sampling zone, three 100 m 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.

3.6.12 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 x 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 were collected and identified. Finally the top 5 cm surface sediments was dug for visible infauna in the quadrat regardless of hand core sample was taken .

3.6.13 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 .

3.6.14 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), AFCD (2018) .

Data Analysis

3.6.15 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

3.6.16 In the present survey, two species of horseshoe crab (total 15 ind.) and Tachypleus tridentatus (total 13 ind.) were recorded. The recorded individuals were mainly distributed along the shoreline from TC3 to ST. Grouping of 2-3 individuals was usually observed on similar substratum (fine sand or soft mud, slightly submerged).Photo records were shown in Figure 3.1 of Appendix O while the complete survey records were listed in Annex II of Appendix O.

3.6.17 Table 3.1 of Appendix O summarizes the survey results of horseshoe crab in the present survey. In general, very low search record was found for both species in TC1, TC3 and ST. No individual of either species was found in TC2.

3.6.18 For Carcinoscorpius rotundicauda, more individuals (10 ind.) were found in TC3 with average body size 36.34 mm (19.25-71.23 mm). In TC1, there were 4 individuals with average body size 38.39 mm (prosomal width ranged 23.24-58.44 mm). In ST, there was only 1 individual with body size 61.20 mm. The three zones were very low in search record (0.2-1.7 ind. hr^-1 person^-1).

3.6.19 There was similar pattern of survey results for Tachypleus tridentatus. Relatively more individuals were found in TC3 (7 ind.) with average body size 34.90 mm (26.30-38.73 mm). In TC1 and ST, there were only 3 individuals with average body size 47.06-49.13 mm (prosomal width ranged 37.37-66.72 mm). The search record was very low (0.5-1.2 ind. hr-1 person-1) for the three zones.

3.6.20 Based on previous monitoring results, there were similar search records of horseshoe crab in TC3 and ST. But it was relatively higher in TC3 in present survey because the survey was conducted under warmer weather in early December. The survey for ST was conducted in mid-December while the ambient temperature dropped significantly. It could decrease the activity rate of horseshoe crab.

3.6.21 In the 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). It indicated the importance of ST as a breeding ground of horseshoe crab. In Jun. 2017, mating pairs of Carcinoscorpius rotundicauda were also found in TC2 (male 175.27 mm, female 143.51 mm) and TC3 (male 182.08 mm, female 145.63 mm) (Figure 3.2 of Appendix O). In Dec. 2017 and Jun. 2018, one mating pair was of Carcinoscorpius rotundicauda was found in TC3 (Dec. 2017: male 127.80 mm, female 144.61 mm; Jun. 2018: male 139 mm, female 149 mm). Figure 3.2 of Appendix O shows the photographic records of all mating pairs found. The recorded mating pairs were found nearly burrowing in soft mud at low tidal level (0.5-1.0 m above C.D.). The smaller male was holding the opisthosoma (abdomen carapace) of larger female from behind. These mating pairs indicated that breeding of horseshoe crab could be possible along the coast of Tung Chung Wan rather than ST only, as long as suitable substratum was available. Based on the frequency of encounter, the shoreline between TC3 and ST should be more suitable mating ground. Moreover suitable breeding period was believed in wet season (Mar - Sep.) because tiny individuals (i.e. newly hatched) were usually recorded in Jun. and Sep. every year.

3.6.22 Despite of mating pair, there were occasional records of large individuals of Carcinoscorpius rotundicauda (prosomal width ranged 114.45 - 178.67 mm, either single or in pair) and Tachypleus tridentatus (prosomal width 103 mm) (Figure 3.3 of Appendix O). In the present survey (Dec. 2018), one large individual of Carcinoscorpius rotundicauda was found in TC3 (prosomal width 148.94 mm). Based on their sizes, it indicated that individuals of prosomal width larger than 100 mm would progress its nursery stage from intertidal habitat to sub-tidal habitat of Tung Chung Wan. These large individuals might move onto intertidal shore occasionally during high tide for foraging and breeding. Because they should be inhabiting sub-tidal habitat most of the time. Their records were excluded from the data analysis to avoid mixing up with juvenile population living on intertidal habitat.

3.6.23 No marked individual of horseshoe crab was recorded in the present survey. Some marked individuals were found in the previous surveys of Sep. 2013, Mar. 2014 and Sep. 2014. All of them were released through a conservation programme in charged 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 crab 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 Sep. 2014.

3.6.24 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

3.6.25 Figures 3.5 and 3.6 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.

3.6.26 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. From Mar. to Jun. 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. No obvious difference of horseshoe crab population was noted between TC3 and ST. In Sep. 2017, the search records of both horseshoe crab species decreased except the Carcinoscorpius rotundicauda in TC3. The survey results were different from previous findings that there were usually higher search records in September. One possible reason was that the serial cyclone hit decreased horseshoe crab activity (totally 4 cyclone records between Jun. and Sep. 2017, to be discussed in 'Seagrass survey' section). From Dec. 2017 to Sep. 2018, the search records of both species increased again to low-moderate level in ST. Relatively higher population fluctuation of Tachypleus tridentatus was observed in TC3.

3.6.27 For TC1, the search record was at low to moderate 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. There were occasional records of 1 to 4 individuals between March and September throughout the monitoring period. The maximum record was 6 individuals only in Jun. 2016.

3.6.28 About the body size, larger individuals of Carcinoscorpius rotundicauda were usually found in ST and TC1 relative to those in TC3 from Sep. 2012 to Jun. 2017. But the body size was higher in TC3 and ST followed by TC1 from Sep. 2017 to Jun. 2018. In Sep. 2018, larger individuals were found in ST and TC1 again. For Tachypleus tridentatus, larger individuals were usually found in ST and TC3 followed by TC1 throughout the monitoring period.

3.6.29 In general, it was obvious that the shoreline along 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 substratum. Although a mating pair of Carcinoscorpius rotundicauda was once found in TC2, the hatching rate and survival rate of newly hatched individuals were believed very low.

Seasonal variation of horseshoe crab population

3.6.30 Throughout the monitoring period, the search record of horseshoe crab declined obviously during dry season especially December (Figures 3.4 and 3.5 of Appendix O). Very low – low search record was found in December from 2012 to 2015 (0-4 ind. of Carcinoscorpius rotundicauda and 0-12 ind. of Tachypleus tridentatus). 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 �aC 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 °C during dawn on 19 Dec.). The horseshoe crab activity would decrease gradually with the colder climate. In December of 2017 and 2018 (present survey), very low search records were found again as mentioned above.

3.6.31 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. In 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)).

3.6.32 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. 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. In Jun. 2017, the number of individuals increased sharply again in TC3 and ST. Although mating pair of Tachypleus tridentatus was not found in previous surveys, there should be new round of spawning in the wet season of 2016. The individuals might have grown to a more conspicuous size in 2017 accounting for higher search record. In Sep. 2017, moderate numbers of individual were found in TC3 and ST indicating a stable population size. In Sep. 2018, the population size was lower while natural mortality was the possible cause.

3.6.33 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 of population located in TC3 and ST. Due to potential breeding last year, Tachypleus tridentatus became common again and distributed in TC3 and ST mainly. 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

3.6.34 Figure 3.7 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 (top of red box) and lower quartile (bottom of blue box)) ranged 40-60 mm while only few individuals were found. From Mar. 2014 to Sep. 2018, the median prosomal width (middle line of whole box) and major size (whole box) decreased after Mar. of every year. It was due to more small individuals found in June indicating new rounds of spawning. 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 larger juveniles (upper whisker), the size range was quite variable (prosomal width 60-90 mm) along the sampling months. Juveniles reaching this size might gradually migrate to sub-tidal habitats.

3.6.35 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 Jun. 2017, similar increasing trend of major size was noted with much higher number of individuals. It reflected new round of spawning. In Sep. 2017, the major size decreased while the trend was different from previous two years. Such decline might be the cause of serial cyclone hit between Jun. and Sep. 2017 (to be discussed in the 'Seagrass survey' section). From Dec. 2017 to Sep. 2018, increasing trend was noted again. Across the whole monitoring period, the larger juveniles (upper whisker) usually reached 60-80 mm in prosomal width, even 90 mm occasionally. Juveniles reaching this size might gradually migrate to sub-tidal habitats.

Box plot of horseshoe crab populations in ST

3.6.36 Figure 3.8 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. 2018, the size of major population decreased and more small individuals (i.e. lower whisker) were recorded after Jun. of every year. It indicated new round of spawning. Also, there were similar increasing trends of body size from Sep. to Jun. of next year between 2014 and 2017. It indicated a stable growth of individuals. Across the whole monitoring period, the larger juveniles (i.e. upper whisker) usually ranged 60-80 mm in prosomal width except one individual (prosomal width 107.04 mm) found in Mar. 2017. It reflected juveniles reaching this size would gradually migrate to sub-tidal habitats.

3.6.37 For Tachypleus tridentatusa, 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 60-70 mm. As mentioned, the large juveniles 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 juveniles 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. In 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, 40-70 mm in Mar. 2017 and 50-60mm in Jun. 2017. Based on overall higher number of small individuals from Jun. 2016 to Sep. 2017, it indicated another round of spawning. From Sep. 2017 to Jun. 2018, the major size range increased slightly from 40-50 mm to 45-60 mm indicating a continuous growth. In Sep. 2018, decrease of major size was noted again that might reflect new round of spawning. Throughout the monitoring period, the larger juveniles ranged 60-80 mm in prosomal width. Juveniles reaching this size would gradually migrate to sub-tidal habitats.

3.6.38 As a summary for horseshoe crab populations in TC3 and ST, there were spawning of Carcinoscorpius rotundicauda from 2014 to 2018 while the spawning time should be in spring. The population size was consistent in these two sampling zones. For Tachypleus tridentatus, small individuals were rarely found in both zones 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. From 2016 to 2018, new rounds of spawning were recorded in ST while the population size increased to a moderate level.

Impact of the HKLR project

3.6.39 It was the 25^th survey of the EM&A programme during the construction period. Based on the monitoring results, impact of the HKLR project was not detected on horseshoe crabs. The population change was mainly determined by seasonal variation while new rounds of spawning were observed for both species. Abnormal phenomenon (e.g. very few numbers of horseshoe crab individuals in wet season, large number of dead individuals on the shore) had not been reported.

Seagrass Beds

3.6.40 Since the commencement of the EM&A monitoring programme, two species of seagrass Halophila ovalis and Zostera japonica were recorded in TC3 and ST (Figure 3.9 of Appendix O). In general, Halophila ovalis was occasionally found in TC3 in few, small to medium patches. But it was commonly found in ST in medium to large seagrass bed. Moreover, it had sometimes grown extensively and had covered significant mudflat area at 0.5-2.0 m above C.D. between TC3 and ST. Another seagrass species Zostera japonica was found in ST only. It was relatively lower in vegetation area and was co-existing with Halophila ovalis nearby the mangrove strand at 2.0 m above C.D..

3.6.41 Table 3.2 of Appendix O summarizes the results of present seagrass beds survey. Seagrass beds were found in ST only. There were two low-medium sized, horizontal strands of Halophila ovalis with total seagrass bed area ~ 404 m² (Figure 3.10 of Appendix O). The larger strand had area ~264 m² in medium-high vegetation coverage 50-85%, located at tidal zone 1.5-2.0 m above C.D nearby mangrove plantation. At close vicinity, there was a smaller horizontal strand (~140 m², low coverage 5-20%). Another seagrass species Zostera japonica was not found in present survey. Annex III of Appendix O shows the complete record of seagrass survey.

3.6.42 According to the previous results, majority of seagrass bed was confined in ST, the temporal change of both seagrass species were investigated in details:

Temporal variation of seagrass beds

3.6.43 Figure 3.11 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 (105.4 m²) in Jun. 2017. And it was no longer co-existing with Halophila ovalis. Between Sep. 2014 and Jun. 2017, an increasing trend was noticed from Sep. to Jun. of next year followed by a rapid decline in Sep. of next year. It was possibly the causes of heat stress, typhoon and stronger grazing pressure during wet season. However such increasing trend was not found from Sep. 2017 to Dec. 2018 (present survey) while no patch of Zostera japonica was found.

3.6.44 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 large 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; 14^th-17^th Sep.: Kalmaegi, maximum signal number 8SE) before the seagrass survey dated 21^st 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.

3.6.45 In Dec. 2014, all the seagrass patches of Halophila ovalis disappeared in ST. Figure 3.12 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 unfavourable conditions (Fong, 1998).

Unfavourable conditions to seagrass Halophila ovalis

3.6.46 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.

3.6.47 Prolonged light deprivation due to turbid water would be another unfavouable 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).

3.6.48 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 1st to 10th 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.

3.6.49 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 unfavourable condition in the coming months.

Recolonization of seagrass beds

3.6.50 Figure 3.12 of Appendix O shows the recolonization of seagrass bed area in ST from Dec. 2014 to Jun. 2017. From Mar. to Jun. 2015, 2-3 small patches of Halophila ovalis were newly found co-inhabiting 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-selected 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. The total seagrass bed decreased to 12550 m². From Mar. to Jun. 2017, the seagrass bed area remained generally stable (12438-17046.5 m²) but the vegetation coverage fluctuated (20-50% in Mar. 2017 to 80-100% in Jun. 2017). The whole recolonization process took about 2.5 years.

Re-disappearance of seagrass bed

3.6.51 In Sep 2017, the whole seagrass bed of Halophila ovalis disappeared again along the shore of TC3 and ST (Figure 3.12 of Appendix O). It was similar to the case between Sep. and Dec. 2014. As mentioned, strong water current (e.g. cyclone) or deteriorated water quality (e.g. high turbidity) were the possible causes.

3.6.52 Between the survey periods of Jun. and Sep. 2017, there were four tropical cyclone records in Hong Kong (Merbok in 12-13^th, Jun.; Roke in 23^rd, Jul.; Hato in 22-23^rd, Aug.; Pakhar in 26-27^th, Aug.) (online database of Hong Kong Observatory). All of them reaches signal 8 or above especially Hato (highest signal 10).

3.6.53 According to the water quality monitoring results (Jul. to Aug. 2017) of the two closest monitoring stations SR3 and I5 of the respective EM&A programme, the overall water quality was in normal fluctuation. There was one exceedance of suspended solids (SS) at SR3 on 12 Jul. 2017. The SS concentration reached 24.7 mg/L during mid-ebb tide. It exceeded the Action Level (≤23.5 mg/L) but was far below the Limit Level (≤34.4 mg/L). Since such exceedance was slight and temporary, its effect to seagrass bed should be minimal.

3.6.54 Overall, the disappearance of seagrass beds in ST was believed the cause of serial cyclone hit in Jul and Aug. 2017. Based on previous findings, the seagrass beds of both species were expected to recolonize the mudflat as long as the vicinal water quality was normal. The whole recolonization process (from few, small patches to extensive strand) would be gradual lasting minimum 2 years. From Dec. 2017 to Mar. 2018, there was still no recolonization of few, small patches of seagrass at the usual location (Fig. 3.12). It was different from previous round (Mar. 2015 - Jun. 2017). Until Jun. 2018, new, small-medium seagrass patches were found at the usual location (seaward side of mangrove plantation at 2.0 m C.D.) again, indicating the recolonization. However, the seagrass bed area decreased sharply to 22.5 m² in Sep. 2018. Again, it was believed the hit of super cyclone in Sep. 2018 (Mangkhut on 16^th Sep., highest signal 10). In Dec. 2018 (present survey), the seagrass bed area increased again. Relatively, it would occour later and slower than previous round (more than 2 years).

Impact of the HKLR project

3.6.55 It was the 25^th survey of the EM&A programme during the construction period. Throughout the monitoring period, the disappearance of seagrass beds was believed the cause of cyclone hits rather than impact of HKLR project. There was slow and gradual recolonization in the following dry season.

Intertidal Soft Shore Communities

3.6.56 Table 3.3 and Figure 3.13 of Appendix O show the substratum types along the horizontal transact at every tidal level in all sampling zones. The relative distribution of substratum types 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:

· In TC1, high percentages of ‘Gravels and Boulders’ (80-90%) were recorded at high and mid tidal levels. Relatively higher percentages of ‘Gravels and Boulders’ (40%) and ‘Soft mud’ (40%) were recorded at low tidal level.

· In TC2, high percentages of ‘Sands’ (60%) was recorded at high tidal level. At mid tidal level, there was higher percentage of ‘Soft mud’ (60%) followed by ‘Gravels and Boulders’ (40%). At low tidal level, the major substratum type was 'Soft mud' (80%).

· In TC3, higher percentage of ‘Sands’ (70%) was recorded followed by ‘Soft mud’ (30%) at high tidal level. At mid tidal level, higher percentages of ‘Soft mud’ (60%) and ‘Sands’ (40%) were recorded. At low tidal level, the main substratum type was ‘Gravels and Boulders’ (90%).

· In ST, ‘Gravels and Boulders’ was the main substratum type (100%) at high tidal level. At mid tidal level, there were even distribution of ‘Gravels and Boulders’ (50%) and ‘Sands’ (50%). At low tidal level, ‘Sands’ was the main substratum type (80%).

3.6.57 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.

3.6.58 Table 3.4 of Appendix O lists the total abundance, density and number of taxon of every phylum in this survey. A total of 14429 individuals were recorded. Mollusca was clearly the most abundant phylum (total abundance 14217 ind., density 474 ind. m-2, relative abundance 98.5 %). The second and third abundant phyla were Arthropoda (114 ind., 4 ind. m-2, 0.8 %) and Annelida (70 ind., 2 ind. m-2, 0.5 %) respectively. Relatively other phyla were very low in abundances (density £1 ind. m-2, relative abundance £0.1 %). Moreover, the most diverse phylum was Mollusca (33 taxa) followed by Arthropoda (10 taxa) and Annelida (9 taxa). There was 1-2 taxa recorded only for other phyla.

3.6.59 The taxonomic resolution and complete list of recorded fauna are shown in Annexes IV and V of Appendix O respectively. As reported in Jun. 2018, taxonomic revision of three potamidid snail species was conducted according to the latest identification key published by Agriculture, Fisheries and Conservation Department (details see AFCD, 2018), the species names of following gastropod species were revised:

· Cerithidea cingulata was revised as Pirenella asiatica

· Cerithidea djadjariensis was revised as Pirenella incisa

· Cerithidea rhizophorarum was revised as Cerithidea moerchii

Moreover, taxonomic revision was conducted on another snail species while the specie name was revised.:

· Batillaria bornii was revised as Clypeomorus bifasciata

3.6.60 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 (2195-4738 ind.) varied among the four sampling zones while the phyla distributions were similar. In general, Mollusca was the most dominant phylum (no. of individuals: 2152-4690 ind.; relative abundance 97.9-99.1 %; density 287-625 ind. m^-2). Other phyla were much lower in number of individuals. Arthropoda (16-49 ind.; 0.6-1.1 %; 2-7 ind. m^-2) and Annelida (2-36 ind.; 0.1-0.9 %; 0-5 ind. m^-2) were common phyla relatively. Other phyla were very low in abundance in all sampling zones.

Dominant species in every sampling zone

3.6.61 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). Few listed species of high or very high density (> 250 ind. m^-2) were regarded as dominant species. Other listed species of lower density (< 50 ind. m^-2) were regarded as common species.

3.6.62 In TC1, the substratum was mainly ‘Gravels and Boulders’ at high and mid tidal levels. The high tidal level was clearly dominated by gastropod Batillaria multiformis (514 ind. m^-2, relative abundance 68 %) at very high density followed by gastropod Pirenella incisa (98 ind. m^-2, 13 %). At mid tidal level, gastropod Batillaria multiformis (184 ind. m^-2, 33 %) and Monodonta labio (156 ind. m^-2, 28 %) were abundant at moderate densities. Rock oyster Saccostrea cucullata (86 ind. m^-2, 16 %, attached on boulders) was also abundant at low-moderate density. At low tidal level (main substratum types ‘Gravels and Boulders’ or ‘Soft mud’), rock oyster Saccostrea cucullata (207 ind. m^-2, 35 %) was more abundant at moderate density. Other gastropods Pirenella incisa (103 ind. m^-2, 17 %), Batillaria zonalis (75 ind. m^-2, 13 %) and Lunella coronata (61 ind. m^-2, 10 %) were found at low-moderate densities.

3.6.63 In TC2, the substratum types were mainly 'Sands' at high tidal level. Gastropods Pirenella incisa (100 ind. m^-2, 28 %), Pirenella asiatica (63 ind. m^-2, 17 %) and rock oyster Saccostrea cucullata (68 ind., 19 %, attached on boulders) were abundant at low-moderate densities. Other gastropods Batillaria zonalis (45 ind. m^-2, 13 %) and Batillaria multiformis (40 ind. m^-2, 11 %) were also common. At mid tidal level (main substratum type ‘Soft mud’), rock oyster Saccostrea cucullata (124 ind. m^-2, 36 %) was abundant at moderate density followed by gastropods Pirenella incisa (63 ind. m^-2, 18 %) and Batillaria zonalis (49 ind. m^-2, 14 %). At low tidal level (main substratum type ‘Soft mud’), gastropod Batillaria zonalis (70 ind. m^-2, 41 %) was abundant at low-moderate desnity followed by common rocky oyster Saccostrea cucullata (31 ind. m^-2, 18 %) and gastropod Pirenella asiatica (19 ind. m^-2, 11 %).

3.6.64 In TC3, the substratum types were either ‘Sands’ or ‘Soft mud’ at high and mid tidal levels. Gastropod Pirenella incisa (233-365 ind. m^-2, 47-64 %) was dominant followed by gastropods Pirenella asiatica (67-126 ind. m^-2, 12-25 %) and Batillaria multiformis (80-82 ind. m^-2, 14-16 %) at low-moderate densities. At low tidal level (major substratum: ‘Gravels and Boulders’), rock oyster Saccostrea cucullata (266 ind. m^-2, 38 %, attached on boulders) and gastropod Monodonta labio (220 ind. m^-2, 31 %) were abundant at moderate densities, followed by gastropod Lunella coronata (77 ind. m^-2, 11 %).

3.6.65 In ST, the major substratum type was ‘Gravels and Boulders’ at high tidal level. There were few abundant gastropod species at low-moderate densities including Batillaria multiformis (123 ind. m^-2, 26 %), Monodonta labio (97 ind. m^-2, 20 %), Lunella coronata (52 ind. m^-2, 11 %) and Clypeomorus bifasciata (50 ind. m^-2, 10 %). At mid and low tidal levels (main substratum types ‘Gravels and Boulders’ and 'Sands'), rock oyster Saccostrea cucullata (52-143 ind. m^-2, 22-28 %, attached on boulders) was more abundant at low-moderate densities. Other abundant gastropods Pirenella incisa (44-82 ind. m^-2, 16-19 %), Monodonta labio (36-77 ind. m^-2, 15-16 %) and Lunella coronata (25-76 ind. m^-2, 11-15 %) were at low-moderate densities. Besides, gastropod Pirenella asiatica (74 ind. m^-2, 14 %) was also abundant at mid tidal level.

3.6.66 In general, there was no consistent zonation pattern of species distribution across all sampling zones and tidal levels. The species distribution was determined by the type of substratum primarily. In general, gastropods Pirenella incisa (total number of individuals: 2921 ind., relative abundance 20.2 %), Batillaria multiformis (2628 ind., 18.2 %), Pirenella asiatica (1421 ind., 9.8 %) and Batillaria zonalis (769 ind., 5.3 %) were the most commonly occurring species on sandy and soft mud substrata. Rock oyster Saccostrea cucullata (2635 ind., 18.3 %), gastropods Monodonta labio (1806 ind., 12.5 %) and Lunella coronata (881 ind., 6.1 %) were the commonly occurring species inhabiting gravel and boulders substratum.

Biodiversity and abundance of soft shore communities

3.6.67 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.

3.6.68 Among the sampling zones, the mean species number was similar (6-9 spp. 0.25 m^-2) among the four sampling zones. The mean densities of TC1 and TC3 (591-632 ind. m^-2) were higher than ST (409 ind. m^-2) followed by TC2 (293 ind. m^-2). Overall, ST was relatively higher in H' (1.6) and J (0.8) due to higher species number and even taxa distribution. In TC1 and TC3, higher densities were mainly accounted by 1-2 abundant gastropods. It resulted in lower H’ (1.2-1.3) and J (0.6-0.7). In TC2, lower species number and density also resulted in lower H' (1.3) and J (0.7).

3.6.69 Among the tidal levels, there were slightly increasing trends of mean species number, H' and J from high to low tidal level in TC1 and TC3 but vice versa in TC2 and ST. A general decreasing trend of mean density was observed from high to low tidal level in TC1, TC2 and ST. As mentioned, the spatial differences of these biological parameters were highly related to substratum types.

3.6.70 Figures 3.14 to 3.17 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 limited range.

3.6.71 From Jun. to Dec. 2017, there were steady decreasing trends of mean species number and density in TC2, TC3 and ST regardless of tidal levels. It might be an unfavourable change reflecting environmental stresses. The heat stress and serial cyclone hit were believed the causes during the wet season of 2017. From Mar. to Oct. 2018, increases of mean species number and density were observed in all sampling zones. It indicated the recovery of intertidal community.

Impact of the HKLR project

3.6.72 It was the 25^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. Abnormal phenomena (e.g. rapid, consistent or non-seasonal decline of fauna densities and species number) were not recorded.

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		Dec 2018	Jan 2019	Feb 2019
Air Quality	1-hr TSP	5, 11, 17, 21, 27 and 31	4, 10, 16, 22 and 28	1, 4, 8, 14, 20 and 26
Air Quality	24-hr TSP	4, 10, 14, 20, 24 and 28	3, 9, 15, 21, 25 and 31	2, 8, 13, 19 and 25
Noise		5, 11, 19, 27 and 31	10, 16, 22 and 28	4, 14, 20 and 26
Water Quality		3, 5, 7, 10, 12, 14, 17, 19, 21, 24, 26, 28 and 31	2, 4, 7, 9, 11, 14, 16, 18, 21, 23, 25, 28 and 30	1, 4, 6, 8, 11, 13, 15, 18, 20, 22, 25 and 27
Chinese White Dolphin		3, 5, 10 and 12	2, 3, 7 and 14	1, 14, 20, 25 and 26
Mudflat Monitoring (Ecology)		1, 2, 11, 15 and 16	-	-
Mudflat Monitoring (Sedimentation rate)		1	-	-
Site Inspection		5, 12, 19 and 28	2, 9, 16 and 25	1, 4, 11 and 22

Description of Activities	Site Area
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
Backfilling at Scenic Hill Tunnel (Cut & Cover Tunnel)	Portion X
Works for diversion	Airport Road
Establishment of site access	Airport Road/ Airport Express Line/ East Coast Road
Finishing works for Highway Operation and Maintenance Area Building	Portion X
Finishing works for Scenic Hill Tunnel West Portal Ventilation building	West Portal

	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 Complaint No.	Date of Complaint Received	Description of Environmental Complaint
Complaint No COM-2018-158	SOR referred the email from HyD to Contractor, ET and IEC/ENPO on 24 December 2018	Other: Construction work on Sunday Morning

1 Introduction

1.1.5 This is the twenty-sixth 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 December 2018 to 28 February 2019.

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 EM&A Requirement

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 and Limit Level exceedances of 1-hr TSP and 24-hr TSP were recorded at AMS5 and AMS6 during the reporting period.

3.2.3 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.

3.3.2 No Action/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.

3.4.2 No Action and Limit Level exceedances of turbidity level and dissolved oxygen were recorded during reporting period. No Limit Level exceedance of suspended solids were recorded during the reporting period.

3.4.4 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 December 2018 to February 2019, 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 579.99 km, while the effort on secondary lines was 221.75 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 Appendix J.

3.5.13 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 in NEL during HKLR03 monitoring surveys.

Distribution

Encounter Rate

Group Size

Table 3.8 Comparison of Average Dolphin Group Sizes between Reporting Period (Dec 2018 – Feb 2019) and Baseline Monitoring Period (Sep – Nov 2011)

3.5.31 Notably, with the exception of three medium-sized groups with 5-7 animals, the other nine dolphin groups were small with 1-4 individuals per group only (Annex II of Appendix J).

Habitat Use

3.5.34 Notably, 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).

Mother-calf Pairs

Activities and Associations with Fishing Boats

3.5.40 Two of the 12 dolphin groups were engaged in feeding activities, while none of them was engaged in socializing, traveling or milling/resting activity during the three-month study period.

3.5.43 Notably, none of the 12 dolphin groups was found to be associated with any operating fishing vessel during the present impact phase period.

Summary Photo-identification works

3.5.44 From December 2018 to February 2019, about 1,200 digital photographs of Chinese White Dolphins were taken during the impact phase monitoring surveys for the photo-identification work.

3.5.46 Notably, only one of these individuals (NL259) was also sighted in WL waters during the HKLR09 monitoring surveys under the same three-month period.

Individual range use

3.5.47 Ranging patterns of the 16 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

3.5.60 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.

3.5.61 The dolphin specialists of the projects confirmed that the CWD sighting around the North of Sha Chau and Lung Kwu Chau Marine Park (SCLKCMP) has significantly decreased, and it was likely related to the re-routing of high speed ferry (HSF) from Skypier.

3.5.62 ET will keep reviewing the implementation status of the dolphin related mitigation measures and remind the contractor to implement the relevant measures.

3.5.63 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.

3.5.64 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.

3.5.68 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(N)) as in the EM&A Manual. The water quality monitoring location (SR3(N)) is shown in Figure 2.1.

3.6.4 Impact water quality monitoring in San Tau (monitoring station SR3(N)) was conducted in December 2018. The monitoring parameters included dissolved oxygen (DO), turbidity and suspended solids (SS).

3.6.5 The Impact monitoring result for SR3(N) were extracted and summarised in Table 3.11:

Sampling Zone

Horseshoe Crabs

Seagrass Beds