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Contract No. HY/2011/03
Hong Kong-Zhuhai-Macao
Bridge Hong Kong Link Road
Section between Scenic
Hill and Hong Kong Boundary Crossing Facilities
Quarterly EM&A
Report No. 43 (March to May 2023)
22 August 2023
Revision 1
Main
Contractor
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Designer
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Contents
Executive Summary
1...... Introduction. 1
1.1
Basic Project Information. 1
1.2
Project Organisation. 1
1.3
Construction Programme. 1
1.4
Construction Works Undertaken During the Reporting Period. 2
2.......
EM&A Requirement 3
2.1
Summary of EM&A Requirements. 3
2.2
Action and Limit Levels. 4
2.3
Event Action Plans. 5
2.4
Mitigation Measures. 5
3.......
Environmental Monitoring and Audit 6
3.1
Implementation of Environmental Measures. 6
3.2
Air Quality Monitoring Results. 6
3.3
Noise Monitoring Results. 7
3.4
Water Quality Monitoring Results. 7
3.5
Dolphin Monitoring Results. 8
3.6
Mudflat Monitoring Results. 15
3.7
Solid and Liquid Waste Management Status. 31
3.8
Environmental Licenses and Permits. 31
4.......
Environmental Complaint and Non-compliance. 32
4.1
Environmental Exceedances. 32
4.2
Summary of Environmental Complaint, Notification of Summons and
Successful Prosecution. 32
5.......
Comments, Recommendations and Conclusion. 33
5.1
Comments. 33
5.2
Recommendations. 33
5.3
Conclusions. 33
Figures
Figure 1.1
Location of the Site
Figure 2.1
Environmental Monitoring Stations
Figure 2.2
Transect Line Layout in Northwest and Northeast Lantau Survey Areas
Appendices
Appendix A
Environmental Management Structure
Appendix B
Construction Programme
Appendix C
Location of Works Areas
Appendix D
Event and Action Plan
Appendix E
Implementation Schedule of Environmental Mitigation Measures
Appendix F
Site Audit Findings and Corrective Actions
Appendix G
Air Quality Monitoring Data and Graphical Plots
Appendix H
Noise Monitoring Data and Graphical Plots
Appendix I
Water Quality Monitoring Data and Graphical Plots
Appendix J
Dolphin Monitoring Results
Appendix K
Waste Flow Table
Appendix L
Summary of Environmental Licenses and Permits
Appendix M
Record of ¡§Notification of Environmental Quality Limit Exceedances¡¨ and Record
of ¡§Notification of Summons and Prosecutions¡¨
Appendix N
Cumulative Statistics on Complaints
Appendix O
Mudflat Monitoring Results
Executive Summary
The Hong Kong-Zhuhai-Macao
Bridge (HZMB) Hong Kong Link Road (HKLR) serves to connect the HZMB Main Bridge
at the Hong Kong Special Administrative Region (HKSAR) Boundary and the HZMB
Hong Kong Boundary Crossing Facilities (HKBCF) located at the north eastern
waters of the Hong Kong International Airport (HKIA).
The HKLR project has been
separated into two contracts. They are Contract No. HY/2011/03 Hong
Kong-Zhuhai-Macao Bridge Hong Kong Link Road-Section between Scenic Hill and
Hong Kong Boundary Crossing Facilities (hereafter referred to as the Contract)
and Contract No. HY/2011/09 Hong Kong-Zhuhai-Macao Bridge Hong Kong Link
Road-Section between HKSAR Boundary and Scenic Hill.
China State Construction
Engineering (Hong Kong) Ltd. was awarded by Highways Department as the
Contractor to undertake the construction works of Contract No. HY/2011/03. The
main works of the Contract include land tunnel at Scenic Hill, tunnel
underneath Airport Road and Airport Express Line, reclamation and tunnel to the
east coast of the Airport Island, at-grade road connecting to the HKBCF and
highway works of the HKBCF within the Airport Island and in the vicinity of the
HKLR reclamation. The Contract is part of the HKLR Project and HKBCF
Project, these projects are considered to be ¡§Designated Projects¡¨, under
Schedule 2 of the Environmental Impact Assessment (EIA) Ordinance (Cap 499) and
EIA Reports (Register No. AEIAR-144/2009 and AEIAR-145/2009) were prepared for
the Project. The current Environmental Permit (EP) EP-352/2009/D for HKLR
and EP-353/2009/K for HKBCF were issued on 22 December 2014 and 11 April 2016,
respectively. These documents are available through the EIA Ordinance Register.
The construction phase of Contract was
commenced on 17 October 2012.
BMT Hong Kong Limited was
appointed by the Contractor to implement the Environmental Monitoring &
Audit (EM&A) programme for the Contract in accordance with the Updated
EM&A Manual for HKLR (Version 1.0) and provided environmental team services
to the Contract until 31 July 2020.
Meinhardt Infrastructure and
Environment Limited has been appointed by the Contractor to implement the
Environmental Monitoring & Audit (EM&A) programme for the Contract in
accordance with the Updated EM&A Manual for HKLR (Version 1.0) and provide
environmental team services to the Contract with effective from 1 August 2020.
Ramboll Hong Kong Limited was employed
by HyD as the Independent Environmental Checker (IEC) and Environmental Project
Office (ENPO) for the Project until 30 September 2022.
ANewR Consulting Limited has been
employed by HyD as the Independent Environmental Checker (IEC) and Environmental
Project Office (ENPO) for the Project with effective from 1 October 2022.
This is the forty-third
Quarterly EM&A report for the Contract which summarizes the monitoring
results and audit findings of the EM&A programme during the reporting
period from 1 March 2023 to 31 May 2023.
Environmental Monitoring and Audit Progress
The EM&A programme were
undertaken in accordance with the Updated EM&A Manual for HKLR (Version
1.0). A summary of the monitoring activities during this reporting period is
presented as below:
Monitoring Activity
|
Monitoring
Date
|
Mar 2023
|
Apr 2023
|
May
2023
|
Air Quality
|
1-hr TSP at AMS5
|
6, 10, 16, 22 and 28
|
3, 6, 11, 17, 21 and 27
|
3, 9, 15, 19, 24 and 30
|
1-hr TSP at AMS6
|
Not applicable.(see remark 1)
|
Not applicable.(see remark 1)
|
Not applicable.(see remark 1)
|
24-hr TSP at
AMS5
|
3, 9, 15, 21, 27 and 31
|
6, 11, 14, 20, and 26
|
2, 8, 12, 18, 23 and 29
|
24-hr TSP at
AMS6
|
Not applicable.(see remark 1)
|
Not applicable.(see remark 1)
|
Not applicable.(see remark 1)
|
Noise
|
6, 16, 22 and 28
|
3, 11, 17 and 27
|
3, 9, 15, 24 and 30
|
Water Quality
|
1, 3, 6, 8, 10, 13, 15, 17, 20, 22, 24, 27, 29 and 31
|
3, 5, 7, 10, 12, 14, 17, 19, 21, 24, 26 and 28
|
1, 3, 5, 8, 10, 12, 15, 17, 19, 22, 24, 26, 29 and
31
|
Chinese White Dolphin
|
3, 7, 16 and 24
|
3, 6, 11 and 27
|
2, 5, 9 and 10
|
Mudflat
Monitoring (Ecology)
|
23, 24, 25 and 26
|
-
|
-
|
Mudflat
Monitoring (Sedimentation rate)
|
22
|
-
|
-
|
Site Inspection
|
7, 16, 22 and 31
|
4, 12, 18, and 28
|
4, 10, 16, 25 and 31
|
Remarks:
1) The existing air quality monitoring
location AMS6 ¡V Dragonair / CNAC (Group)Building (HKIA) was handed over to
Airport Authority Hong Kong on 31 March 2021. 1-hr and 24-hr TSP monitoring at
AMS6 was temporarily suspended starting from 1 April 2021. A new alternative
air quality monitoring location is still under processing during the reporting
period.
The access to the
WQM station SR4(N2) (Coordinate: E814688, N817996) is blocked by the silt
curtains of the Tung Chung New Town Extension (TCNTE) project. Water quality
monitoring was temporarily conducted at alternative stations, namely SR4(N3)
(Coordinate: E814779, N818032) in October and November 2022. Alternative
monitoring station SR4(N3) (Coordinate: E814779, N818032) is proposed to
replace the monitoring station SR4(N2). Proposal for permanently relocating the
aforementioned station is in progress.
As confirmed by the Contractor, the construction site of the Contract
No. 2011/03 was closed and no
construction works were conducted on 22, 23 and 24 January 2023. As such, no impact
water quality
monitoring was scheduled on 23 January 2023.
Breaches of Action and Limit
Levels
A summary of environmental
exceedances for this reporting period is as follows:
Environmental Monitoring
|
Parameters
|
Action Level (AL)
|
Limit Level (LL)
|
Air Quality
|
1-hr TSP
|
0
|
0
|
24-hr TSP
|
0
|
0
|
Noise
|
Leq (30 min)
|
0
|
0
|
Water Quality
|
Suspended solids level (SS)
|
0
|
0
|
Turbidity level
|
0
|
0
|
Dissolved oxygen level (DO)
|
0
|
0
|
Dolphin Monitoring
|
Quarterly Analysis (Mar 2023 to May 2023)
|
0
|
1
|
The Environmental Team
investigated all exceedance and found that they was not project related.
All investigation report for
exceedance of the Contract has been submitted to ENPO/IEC for comments and/or
follow up to identify whether the exceedances occurred related to other HZMB
contracts.
Implementation of
Mitigation Measures
Site inspections were carried out
to monitor the implementation of proper environmental pollution control and
mitigation measures for the Project. Potential environmental impacts due to the
construction activities were monitored and reviewed.
Complaint Log
There
was no complaints received in relation to the environmental impacts during this
reporting period.
Notifications of
Summons and Prosecutions
There
were no notifications of summons or prosecutions received during this reporting
period.
Reporting Changes
This
report has been developed in compliance with the reporting requirements for the
subsequent EM&A reports as required by the Updated EM&A Manual for HKLR
(Version 1.0).
The proposal for the change of
Action Level and Limit Level for suspended solid and turbidity was approved by
EPD on 25 March 2013.
The revised Event and Action
Plan for dolphin monitoring was approved by EPD on 6 May 2013.
The original monitoring station
at IS(Mf)9 (Coordinate: 813273E, 818850N) was observed inside the perimeter
silt curtain of Contract HY/2010/02 on 1 July 2013, as such the original impact
water quality monitoring location at IS(Mf)9 was temporarily shifted outside
the silt curtain. As advised by the Contractor of HY/2010/02 in August
2013, the perimeter silt curtain was shifted to facilitate safe anchorage zone
of construction barges/vessels until end of 2013 subject to construction
progress. Therefore, water quality monitoring station IS(Mf)9 was shifted
to 813226E and 818708N since 1 July 2013. According to the water quality
monitoring team¡¦s observation on 24 March 2014, the original monitoring
location of IS(Mf)9 was no longer enclosed by the perimeter silt curtain of
Contract HY/2010/02. Thus, the impact water quality monitoring works at the
original monitoring location of IS(Mf)9 has been resumed since 24 March 2014.
Transect lines 1, 2, 7, 8, 9
and 11 for dolphin monitoring have been revised due to the obstruction of the
permanent structures associated with the construction works of HKLR and the
southern viaduct of TM-CLKL, as well as provision of adequate buffer distance
from the Airport Restricted Areas. The EPD issued a memo and confirmed
that they had no objection on the revised transect lines on 19 August 2015.
The water quality monitoring
stations at IS10 (Coordinate: 812577E, 820670N) and SR5 (811489E, 820455N) are
located inside Hong Kong International Airport (HKIA) Approach Restricted
Areas. The previously granted Vessel's Entry Permit for accessing stations IS10
and SR5 were expired on 31 December 2016. During the permit renewing process,
the water quality monitoring location was shifted to IS10(N) (Coordinate:
813060E, 820540N) and SR5(N) (Coordinate: 811430E, 820978N) on 2, 4 and 6
January 2017 temporarily. The permit has been granted by Marine Department on 6
January 2017. Thus, the impact water quality monitoring works at original
monitoring location of IS10 and SR5 has been resumed since 9 January 2017.
Transect lines 2, 3, 4, 5, 6
and 7 for dolphin monitoring have been revised and transect line 24 has been
added due to the presence of a work zone to the north of the airport platform
with intense construction activities in association with the construction of
the third runway expansion for the Hong Kong International Airport. The EPD
issued a memo and confirmed that they had no objection on the revised transect
lines on 28 July 2017. The alternative dolphin transect lines are adopted
starting from August¡¦s dolphin monitoring.
A new water quality monitoring
team has been employed for carrying out water quality monitoring work for the
Contract starting from 23 August 2017. Due to marine work of the Expansion of
Hong Kong International Airport into a Three-Runway System (3RS Project),
original locations of water quality monitoring stations CS2, SR5 and IS10 are
enclosed by works boundary of 3RS Project. Alternative impact water quality
monitoring stations, naming as CS2(A), SR5(N) and IS10(N) was approved on 28
July 2017 and were adopted starting from 23 August 2017 to replace the original
locations of water quality monitoring for the Contract.
The role and responsibilities
as the ET Leader of the Contract was temporarily taken up by Mr Willie Wong
instead of Ms Claudine Lee from 25 September 2017 to 31 December 2017.
The topographical condition of
the water monitoring stations SR3 (Coordinate: 810525E, 816456N), SR4
(Coordinate: 814760E, 817867N), SR10A (Coordinate: 823741E, 823495N) and SR10B
(Coordinate: 823686E, 823213N) cannot be accessed safely for undertaking water
quality monitoring. The water quality monitoring has been temporarily conducted
at alternative stations, namely SR3(N) (Coordinate
810689E, 816591N), SR4(N) (Coordinate: 814705E, 817859N) and SR10A(N)
(Coordinate: 823644E, 823484N) since 1 September 2017. The water quality
monitoring at station SR10B was temporarily conducted at Coordinate: 823683E,
823187N on 1, 4, 6, 8 September 2017 and has been temporarily fine-tuned to
alternative station SR10B(N2) (Coordinate: 823689E, 823159N) since 11 September
2017. Proposal for permanently relocating the aforementioned stations was
approved by EPD on 8 January 2018.
The works area WA5 was handed
over to other party on 22 June 2013.
According to latest information
received in July 2018, the works area WA7 was handed over to other party on 28
February 2018 instead of 31 January 2018.
Original WQM stations IS8 and
SR4(N) are located within the active work area of TCNTE project and the access
to the WQM stations IS8 (Coordinate: E814251, N818412) and SR4(N) (Coordinate:
E814705, N817859) are blocked by the silt curtains of the Tung Chung New Town
Extension (TCNTE) project. Alternative monitoring stations IS8(N) (Coordinate:
E814413, N818570) and SR4(N2) (Coordinate: E814688, N817996) are proposed to
replace the original monitoring stations IS8 and SR4(N). Proposal for permanently
relocating the aforementioned stations was approved by EPD on 20 August 2019.
The water quality monitoring has been conducted at stations IS8(N) and SR4(N2)
on 21 August 2019.
There were no marine works
conducted by Contract No. HY/2011/03 since July 2019. A proposal for temporary
suspension of marine related environmental monitoring (water quality monitoring
and dolphin monitoring for the Contract No. HY/2011/03) was justified by the ET
leader and verified by IEC in mid of September 2019 and it was approved by EPD
on 24 September 2019. Water quality monitoring and dolphin monitoring for the
Contract will not be conducted starting from 1 October 2019 until marine works
(i.e. toe loading removal works) be resumed. As discussed with Contract No.
HY/2012/08, they will take up the responsibility from Contract No. HY/2011/03
for the dolphin monitoring works starting from 1 October 2019.
According to information
received in January 2020, the works area WA3 and WA4 were handed over to
Highways Department on 23 December 2019 and 14 March 2019 respectively.
The role and responsibilities as the IEC of the
Contract has been taken up by Mr. Manson Yeung instead of Mr. Ray Yan since 18
May 2020.
Mr. Leslie Leung was
Environmental Team Leader of the Contract for July 2020. The role and
responsibilities as the Environmental Team Leader of the Contract has been
taken up by Ms. Claudine Lee with effective from 1 August 2020.
The existing air quality
monitoring location AMS6 ¡V Dragonair / CNAC (Group) Building (HKIA) was handed
over to Airport Authority Hong Kong on 31 March 2021. 1-hr and 24-hr TSP
monitoring at AMS6 was temporarily suspended starting from 1 April 2021. A new
alternative air quality monitoring location is still under processing.
The role and responsibilities
as the IEC of the Contract has been taken up by Mr Brian Tam instead of Mr
Manson Yeung since 12 April 2021.
The role and responsibilities
as the IEC of the Contract has been taken up by Mr Adi Lee instead of Mr Brian
Tam since 3 May 2022.
The role and responsibilities
as the IEC of the Contract has been taken up by Mr Brian Tam instead of Mr Adi
Lee since 25 July 2022.
The role and responsibilities
as the ENPO Leader of the Contract has been taken up by Mr Louis Kwan from
ANewR Consulting Limited instead of Mr H.Y. Hui from Ramboll Hong Kong Limited
Since 1 October 2022.
The role and responsibilities
as the IEC of the Contract has been taken up by Mr James Choi from ANewR
Consulting Limited instead of Mr Brian Tam from Ramboll Hong Kong Limited since
1 October 2022.
1 Introduction
1.1
Basic Project Information
1.1.1 The Hong Kong-Zhuhai-Macao Bridge (HZMB) Hong Kong Link Road (HKLR)
serves to connect the HZMB Main Bridge at the Hong Kong Special Administrative
Region (HKSAR) Boundary and the HZMB Hong Kong Boundary Crossing Facilities
(HKBCF) located at the north eastern waters of the Hong Kong International Airport
(HKIA).
1.1.2
The HKLR project has been separated into two
contracts. They are Contract No. HY/2011/03 Hong Kong-Zhuhai-Macao Bridge Hong Kong Link
Road-Section between Scenic Hill and Hong Kong Boundary Crossing Facilities
(hereafter referred to as the Contract) and Contract No. HY/2011/09 Hong
Kong-Zhuhai-Macao Bridge Hong Kong Link Road-Section between HKSAR Boundary and
Scenic Hill.
1.1.3 China State Construction Engineering
(Hong Kong) Ltd. was awarded by Highways Department (HyD) as the Contractor to
undertake the construction works of Contract No. HY/2011/03. The Contract
is part of the HKLR Project and HKBCF Project, these projects are considered to
be ¡§Designated Projects¡¨, under Schedule 2 of the Environmental Impact Assessment
(EIA) Ordinance (Cap 499) and EIA Reports (Register No. AEIAR-144/2009 and
AEIAR-145/2009) were prepared for the Project. The current Environmental
Permit (EP) EP-352/2009/D for HKLR and EP-353/2009/K for HKBCF were issued on
22 December 2014 and 11 April 2016, respectively. These documents are available
through the EIA Ordinance Register. The construction phase of Contract was commenced on 17
October 2012. The works area WA5 and WA7 were handed over to other party on 22
June 2013 and 28 February 2018 respectively. The works area WA3 and WA4 were
handed over to Highways Department on 23 December 2019 and 14 March 2019
respectively. Figure
1.1 shows the
project site boundary. The works areas are shown in Appendix C.
1.1.4
BMT Hong Kong Limited was appointed by the
Contractor to implement the EM&A programme for the Contract in accordance
with the Updated EM&A Manual for HKLR (Version 1.0) and provided environmental team services to
the Contract until 31 July 2020.
1.1.5 Meinhardt Infrastructure and
Environment Limited has been appointed by the Contractor to implement the
Environmental Monitoring & Audit (EM&A) programme for the Contract in
accordance with the Updated EM&A Manual for HKLR (Version 1.0) and provide
environmental team services to the Contract with effective from 1 August 2020.
Ramboll Hong Kong Limited was employed by HyD as the Independent Environmental
Checker (IEC) and Environmental Project Office (ENPO) for the Project until 30
September 2022. ANewR Consulting Limited has been appointed by HyD as the
Independent Environmental Checker (IEC) and Environmental Project Office (ENPO)
for the Project since 1 October 2022. The project organization with regard to
the environmental works is provided in Appendix
A.
1.1.6 This is the forty-second Quarterly
Environmental Monitoring and Audit (EM&A) report for the Contract which
summarizes the monitoring results and audit findings of the EM&A programme
during the reporting period from 1 March 2023 to 31 May 2023.
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.
Table 1.1
Construction Activities during Reporting Period
Description of Activities
|
Site Area
|
Landscape maintenance works
|
SHT East Portal
|
Removal of Temporary Toe Loading Platform
|
Portion X
|
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.
Table 2.1
Summary of Impact EM&A Requirements
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
|
Leq (30mins),
L10 (30mins) and
L90 (30mins)
|
NMS 5
|
At least once per week
|
Daytime on normal weekdays (0700-1900 hrs).
|
Water Quality
|
¡P
Depth
¡P
Temperature
¡P
Salinity
¡P
Dissolved Oxygen (DO)
¡P
Suspended Solids (SS)
¡P
DO Saturation
¡P
Turbidity
¡P
pH
|
¡P
Impact Stations:
IS5, IS(Mf)6, IS7, IS8/IS8(N), IS(Mf)9 &
IS10(N),
¡P
Control/Far Field Stations:
CS2(A) & CS(Mf)5,
¡P
Sensitive Receiver Stations:
SR3(N), SR4(N)/ SR4(N2), SR5(N), SR10A(N) & SR10B(N2)
|
Three times per week during mid-ebb and mid-flood
tides (within ¡Ó 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
|
--
|
Remarks:
1) Original WQM stations IS8 and SR4(N)
are located within the active work area of TCNTE project and the access to the
WQM stations IS8 (Coordinate: E814251, N818412) and SR4(N) (Coordinate:
E814705, N817859) are blocked by the silt curtains of the Tung Chung New Town
Extension (TCNTE) project. Alternative monitoring stations IS8(N) (Coordinate:
E814413, N818570) and SR4(N2) (Coordinate: E814688, N817996) are proposed to
replace the original monitoring stations IS8 and SR4(N). Proposal for
permanently relocating the aforementioned stations was approved by EPD on 20
August 2019. The water quality monitoring has been conducted at stations IS8(N)
and SR4(N2) on 21 August 2019.
2) The access to the WQM station SR4(N2)
(Coordinate: E814688, N817996) is blocked by the silt curtains of the Tung
Chung New Town Extension (TCNTE) project. Water quality monitoring was
temporarily conducted at alternative stations, namely SR4(N3) (Coordinate:
E814779, N818032) in October and November 2022. Alternative monitoring station
SR4(N3) (Coordinate: E814779, N818032) is proposed to replace the monitoring
station SR4(N2). Proposal for permanently relocating the aforementioned station
is in progress.
2.2
Action and Limit Levels
2.2.1 Table
2.2 presents the Action and Limit Levels for the 1-hour TSP, 24-hour TSP
and noise level.
Table 2.2 Action and Limit
Levels for 1-hour TSP, 24-hour TSP and Noise
Environmental
Monitoring
|
Parameters
|
Monitoring Station
|
Action Level
|
Limit Level
|
Air Quality
|
1-hr TSP
|
AMS 5
|
352
µg/m3
|
500 µg/m3
|
AMS 6
|
360
µg/m3
|
24-hr TSP
|
AMS 5
|
164
µg/m3
|
260
µg/m3
|
AMS 6
|
173
µg/m3
|
Noise
|
Leq (30 min)
|
NMS 5
|
When one documented complaint is received
|
75 dB(A)
|
2.2.2
The Action and Limit Levels for water quality monitoring are given as in
Table 2.3.
Table 2.3 Action and Limit
Levels for Water Quality
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
|
Notes:
(1) Depth-averaged
is calculated by taking the arithmetic means of reading of all three depths.
(2) For
DO, non-compliance of the water quality limit occurs when monitoring result is
lower that the limit.
(3) For
SS & turbidity non-compliance of the water quality limits occur when
monitoring result is higher than the limits.
(4) The
change to the Action and limit Levels for Water Quality Monitoring for the
EM&A works was approved by EPD on 25 March 2013. Therefore, the amended
Action and Limit Levels are applied for the water monitoring results obtained
on and after 25 March 2013.
2.2.3 The
Action and Limit Levels for dolphin monitoring are shown in Tables 2.4 and
2.5.
Table 2.4 Action
and Limit Level for Dolphin Impact Monitoring
|
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
|
Remarks:
(1)
STG means quarterly average encounter rate of number
of dolphin sightings.
(2)
ANI means quarterly average encounter rate of total
number of dolphins.
(3)
For North Lantau Social Cluster, AL will be triggered
if either NEL or NWL fall below the criteria; LL will be triggered if both NEL
and NWL fall below the criteria.
Table 2.5
Derived Value of Action Level (AL) and Limit Level (LL)
|
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)
|
Remarks:
(1)
STG means quarterly average encounter rate of number
of dolphin sightings.
(2)
ANI means quarterly average encounter rate of total
number of dolphins.
(3)
For North Lantau Social Cluster, AL will be triggered
if either NEL or NWL fall below the criteria; LL will be triggered if both NEL
and NWL fall below the criteria.
2.3.1 The Event Actions Plans for air
quality, noise, water quality, dolphin monitoring and mudflat monitoring and
Action Plan for Landscape Works are annexed in Appendix D.
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
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. Most of the necessary mitigation measures were implemented
properly.
3.1.3
Regular marine travel
route for marine vessels were implemented properly in accordance to the
submitted plan and relevant records were kept properly.
3.1.4
Dolphin Watching Plan
was implemented during the reporting period. No dolphins inside the silt
curtain were observed. The relevant records were kept properly.
3.2
Air Quality Monitoring Results
3.2.1
The monitoring results for 1-hour TSP and 24-hour TSP are summarized in Tables
3.1 and 3.2 respectively. Detailed impact air quality monitoring
results and relevant graphical plots are presented in Appendix G. The existing air quality
monitoring location AMS6 ¡V Dragonair / CNAC (Group) Building (HKIA) was handed
over to Airport Authority Hong Kong on 31 March 2021. 1-hr and 24-hr TSP
monitoring at AMS6 was temporarily suspended starting from 1 April 2021.
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)
|
Mar 2023
|
AMS5
|
48
|
6-99
|
352
|
500
|
AMS6
|
|
|
360
|
Apr 2023
|
AMS5
|
46
|
20 -
73
|
352
|
AMS6
|
|
|
360
|
May 2023
|
AMS5
|
50
|
18 -
158
|
352
|
AMS6
|
|
|
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)
|
Mar
2023
|
AMS5
|
63
|
26-110
|
164
|
260
|
AMS6
|
|
|
173
|
Apr
2023
|
AMS5
|
54
|
33 -
99
|
164
|
AMS6
|
|
|
173
|
May
2023
|
AMS5
|
55
|
38 -
65
|
164
|
AMS6
|
|
|
173
|
3.2.2 No
Action and Limit Level exceedances of 1-hr TSP and 24-hr TSP were recorded at
AMS5 during the reporting period.
3.3
Noise Monitoring Results
3.3.1 The
monitoring results for construction noise are summarized in Table 3.3
and the monitoring results and relevant graphical plots for this reporting
period are provided in Appendix
H.
Table 3.3 Summary of Construction Noise Monitoring Results
Obtained During the Reporting Period
Reporting period
|
Monitoring Station
|
Average Leq (30 mins), dB(A)*
|
Range of Leq (30 mins), dB(A)*
|
Action Level
|
Limit Level Leq (30 mins), dB(A)
|
Mar 2023
|
NMS5
|
58
|
57 ¡V 60
|
When one documented complaint is received
|
75
|
Apr 2023
|
60
|
57 - 64
|
May 2023
|
59
|
57 - 61
|
*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
Other noise sources during the noise monitoring included
aircraft/helicopter noise, construction activities by other parties and human
activities nearby.
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 For marine water quality monitoring,
no Action Level and Limit Level exceedances of dissolved oxygen level,
turbidity level and suspended solid level were recorded during the reporting
period.
3.4.3 Water quality impact sources during
water quality monitoring were 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 ¡V
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
¡V 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 ¡V 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 Northwest Lantau (NWL) and Northeast (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.
3.5.6
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).
3.5.7
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
3.5.8
Behavioural analysis ¡V
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.
3.5.9
Ranging pattern
analysis ¡V Location data of individual dolphins that occurred during the
3-month baseline monitoring period were obtained from the dolphin sighting
database and photo-identification catalogue. To deduce home ranges for
individual dolphins using the fixed kernel methods, the program Animal Movement
Analyst Extension, was loaded as an extension with ArcView© 3.1 along with
another extension Spatial Analyst 2.0. Using the fixed kernel method, the
program calculated kernel density estimates based on all sighting positions,
and provided an active interface to display kernel density plots. The kernel
estimator then calculated and displayed the overall ranging area at 95% UD
level.
Summary of Survey Effort and
Dolphin Sightings
3.5.10 During the period of March to May 2023, 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 From these surveys, a total of 789.77 km of
survey effort was collected, with 96.0% 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, 286.30 km and 503.47 km of
survey effort were conducted in NEL and NWL survey areas respectively.
3.5.12 The total survey effort conducted on primary
lines was 567.56 km, while the effort on secondary lines was 222.21 km. Survey
effort conducted on both primary and secondary lines were on-effort survey
data. A summary table of the survey effort is shown in Annex I of Appendix J.
3.5.13 During the six sets of monitoring surveys
conducted between March and May 2023, a total of two groups of five Chinese
White Dolphins were sighted, and the summary table of dolphin sightings is shown
in Annex II of Appendix
J. Both dolphin
groups were sighted on primary lines during on-effort search.
3.5.14 Notably, the two dolphin groups were both
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/TMCLKL monitoring surveys.
Distribution
3.5.15 Distribution of dolphin sightings made during
the HKLR03 monitoring surveys conducted from March to May 2023 is shown in Figure
1 of Appendix
J).. The two
dolphin groups were both sighted at the southwestern corner of the NWL survey
area (i.e., just to the north of HKLR09 alignment). 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, the dolphin sightings were located
very far away from the HKLR03 and HKBCF reclamation sites as well as along the
TMCLKL bridge alignments (Figure 1 of Appendix J).
3.5.16 Sighting distribution of dolphins during the
present monitoring period (March-May 2023) was drastically different from the
one during the baseline 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 complete abandonment of NEL region by
the dolphins has been consistently recorded in the past seven years of
HKLR03/TMCLKL monitoring.
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 rarely sighted there, and their
distribution was restricted to the southwestern corner of the survey area. This
was in stark contrast to their frequent occurrences throughout NWL waters
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 spring months in 2018-23. Across the
six periods, the majority of dolphin sightings were made consistently and
exclusively at the western end of the North Lantau region, but during the three
spring periods in 2020, 2022 ad 2023, there was even further decline in their
overall occurrence as well as a complete absence particularly in the Sha Chau
and Lung Kwu Chau Marine Park (Figure 2 of Appendix J).
Encounter
Rate
3.5.19 During the present three-month impact phase 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 ¡V November 2011) (Table 3.5).
Table
3.4 Dolphin Encounter Rates
(Sightings Per 100 km of Survey Effort) During Reporting Period (March 2023 to
May 2023)
Survey Area
|
Dolphin Monitoring Dates
|
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)
|
Primary Lines Only
|
Primary Lines Only
|
Northeast Lantau
|
Set 1 (3 & 7 Mar 2023)
|
0.00
|
0.00
|
Set 2 (16 & 24 Mar 2023)
|
0.00
|
0.00
|
Set 3 (3 & 6 Apr 2023)
|
0.00
|
0.00
|
Set 4 (11 & 27 Apr 2023)
|
0.00
|
0.00
|
Set 5 (2 & 5 May 2023)
|
0.00
|
0.00
|
Set 6 (9 & 10 May
2023)
|
0.00
|
0.00
|
Northwest Lantau
|
Set 1 (3 & 7 Mar 2023)
|
1.60
|
6.38
|
Set 2 (16 & 24 Mar 2023)
|
1.72
|
1.72
|
Set 3 (3 & 6 Apr 2023)
|
0.00
|
0.00
|
Set 4 (11 & 27 Apr 2023)
|
0.00
|
0.00
|
Set 5 (2 & 5 May 2023)
|
0.00
|
0.00
|
Set 6 (9 & 10 May
2023)
|
0.00
|
0.00
|
Table 3.5 Comparison
of average dolphin encounter rates from impact monitoring period (March 2023 to
May 2023) and baseline monitoring period (September ¡V 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)
|
Reporting Period
|
Baseline Monitoring Period
|
Reporting Period
|
Baseline Monitoring Period
|
Northeast Lantau
|
0.0
|
6.00 ¡Ó 5.05
|
0.0
|
22.19 ¡Ó 26.81
|
Northwest Lantau
|
0.55 ¡Ó 0.86
|
9.85 ¡Ó 5.85
|
1.35 ¡Ó 2.56
|
44.66 ¡Ó 29.85
|
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) ¡Ó denotes the standard deviation of the average
encounter rates.
3.5.20 To facilitate the comparison with the AFCD
long-term monitoring results, the encounter rates were also calculated for the present
quarter using both primary and secondary survey effort. The encounter rates of
sightings (STG) and dolphins (ANI) in NWL were 0.41 sightings and 1.02 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.
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 near-absence of
dolphins in NEL have been consistently recorded in past quarters of
HKLR03/TMCLKL monitoring since HKLR03 construction began in late 2012 (Table
3.6) This is a serious concern as the dolphin occurrence in NEL in the past
eight years have remained nil when compared to the baseline period. Dolphins
have been virtually absent from NEL waters since the second half of 2015,
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
Winter Quarters of Impact Monitoring Period and Baseline Monitoring Period (Sep
¡V 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 ¡Ó 5.05
|
22.19 ¡Ó 26.81
|
March-May 2013 (HKLR03 Impact)
|
0.42 ¡Ó 1.03
|
0.42 ¡Ó 1.03
|
March-May 2014 (HKLR03 Impact)
|
0.00
|
0.00
|
March-May 2015 (HKLR03 Impact)
|
0.00
|
0.00
|
March-May 2016 (HKLR03 Impact)
|
0.00
|
0.00
|
March-May 2017 (HKLR03 Impact)
|
0.00
|
0.00
|
March-May 2018 (HKLR03 Impact)
|
0.00
|
0.00
|
March-May 2019 (HKLR03 Impact)
|
0.00
|
0.00
|
March-May 2020 (HKLR03 Impact)
|
0.00
|
0.00
|
March-May 2021 (TMCLKL Post-Construction)
|
0.00
|
0.00
|
March-May 2022 (TMCLKL Post-Construction)
|
0.00
|
0.00
|
March-May 2023 (HKLR03 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) ¡Ó denotes the standard deviation of the average
encounter rates.
3.5.22 On the other hand, the average dolphin
encounter rates (STG and ANI) in NWL during the present impact phase monitoring
period were only tiny fractions of the ones recorded during the three-month
baseline period, indicating a dramatic decline in dolphin usage of this survey
area during the present impact phase period (Table 3.7).
3.5.23 Notably, when comparing among the ten quarterly
periods in spring months since 2013, the quarterly encounter rates in NWL in
the past two spring periods plummeted to an exceptionally low level (Table
3.7). The dramatic drop in dolphin occurrence in NWL in recent years should
raise serious concerns, and such temporal trend should be closely monitored in
the upcoming monitoring quarters as the construction activities of HKLR03 works
will soon be completed in coming months.
Table 3.7
Comparison
of Average Dolphin Encounter Rates in Northwest Lantau Survey Area from All
Winter Quarters of Impact Monitoring Period and Baseline Monitoring Period (Sep
¡V 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 ¡Ó 5.85
|
44.66 ¡Ó 29.85
|
March-May 2013 (HKLR03 Impact)
|
7.75 ¡Ó 3.96
|
24.23 ¡Ó 18.05
|
March-May 2014 (HKLR03 Impact)
|
6.51 ¡Ó 3.34
|
19.14 ¡Ó 7.19
|
March-May 2015 (HKLR03 Impact)
|
0.47 ¡Ó 0.73
|
2.36 ¡Ó 4.07
|
March-May 2016 (HKLR03 Impact)
|
0.98 ¡Ó 1.10
|
4.78 ¡Ó 6.85
|
March-May 2017 (HKLR03 Impact)
|
0.93 ¡Ó 1.03
|
5.25 ¡Ó 9.53
|
March-May 2018 (HKLR03 Impact)
|
2.88 ¡Ó 4.81
|
11.12 ¡Ó 22.46
|
March-May 2019 (HKLR03 Impact)
|
1.13 ¡Ó 1.39
|
2.54 ¡Ó 3.00
|
March-May 2020 (HKLR03 Impact)
|
0.56 ¡Ó 0.86
|
0.56 ¡Ó 0.86
|
March-May 2021 (TMCLKL Post-Construction)
|
1.13 ¡Ó 1.37
|
3.44 ¡Ó 4.26
|
March-May 2022 (TMCLKL Post-Construction)
|
0.00
|
0.00
|
March-May 2023 (HKLR03 Impact)
|
0.55 ¡Ó 0.86
|
1.35 ¡Ó 2.56
|
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) ¡Ó denotes the standard deviation of the average
encounter rates.
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 (32nd quarter of the impact phase being assessed), the
p-values for the differences in average dolphin encounter rates of STG and ANI
were 0.0025 and 0.0097 respectively. Even if the alpha
value is set at 0.01, significant differences were still 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 43 quarters of the
HKLR03/TMCLKL monitoring programme 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 dramatically and 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 eight 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). Not only there has been no
sign of recovery of dolphin usage, such usage has continued to fall to
near-absence level, 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.
Action
Level / Limit Level Exceedance
3.5.29
There was a Limit Level
exceedance of dolphin monitoring for the quarterly monitoring data (between
March 2023 and May 2023). Record of ¡§Notification of Environmental Quality
Limit Exceedances¡¨ is provided in Appendix
M. According to the
contractor¡¦s information, toe loading removal works were undertaken for HKLR03
during the quarter of March 2023 to May 2023.
3.5.30
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 ¡V Sham Shui Kok Anchorage (near Brothers Island) as far as
practicable.
3.5.31 Hong Kong-Zhuhai-Macao Bridge Authority (HZMBA)
for the Mainland section of Hong Kong-Zhuhai-Macao Bridge (HZMB) has commenced
an survey on fisheries resources and CWD in the Mainland waters. During the
one-year HZMBA survey between August 2015 to August 2016, the findings of the
HZMBA 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 data were mentioned in Monitoring of Chinese White
Dolphins in Southwest Lantau Waters ¡V Ninth Quarterly Report (March to May
2017) which is available on ENPO¡¦s website.
3.5.32 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
3.5.32that were examined
included the two periods (baseline and impact phases) and two locations (NEL
and NWL).
3.5.33 For the comparison between the baseline period
and the present quarter (32nd quarter of the impact phase being assessed), the p-values
for the differences in average dolphin encounter rates of STG and ANI 0.0025
and 0.0097 respectively in the present quarter. Even if the alpha value is set
at 0.01, significant differences were still detected between the baseline and
present quarter in both the average dolphin encounter rates of STG and ANI.
3.5.34 For comparison between the baseline period and
the cumulative quarters in impact phase (i.e. first 43 quarters of the
HKLR03/TMCLKL monitoring programme 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)
3.5.35 The AFCD monitoring data during
March to May 2023 has been reviewed by the dolphin specialist. During the same
quarter, no dolphin was sighted at all from 275.22 km of survey effort on primary
lines in NEL and NWL. This review has confirmed that the extremely rare
occurrence of dolphins reported by the HKLR03 monitoring surveys in spring 2023
in NEL and NWL survey area is accurate.
3.5.36
All dolphin protective
measures are fully and properly implemented in accordance with the EM&A
Manual, EIA report and EP. 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.
3.5.37
ET will keep reviewing
the implementation status of the dolphin related mitigation measures and remind
the contractor to implement the relevant measures.
3.5.38
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.
3.5.39
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.
3.5.40
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.
3.5.41
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. 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.
3.5.42
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 22 March 2023. The mudflat surface levels at the four established
monitoring stations and the corresponding XYZ HK1980 GRID coordinates are
presented in Table 3.8 and Table 3.9.
Table 3.8
Measured Mudflat Surface Level Results
|
Baseline Monitoring
(September 2012)
|
Impact Monitoring
(March
2023)
|
Monitoring Station
|
Easting
(m)
|
Northing (m)
|
Surface Level
(mPD)
|
Easting
(m)
|
Northing (m)
|
Surface Level
(mPD)
|
S1
|
810291.160
|
816678.727
|
0.950
|
810291.137
|
816678.715
|
1.115
|
S2
|
810958.272
|
815831.531
|
0.864
|
810958.280
|
815831.527
|
0.964
|
S3
|
810716.585
|
815953.308
|
1.341
|
810716.585
|
815953.308
|
1.448
|
S4
|
811221.433
|
816151.381
|
0.931
|
811221.422
|
816151.386
|
1.116
|
Table 3.9
Comparison of Measurement
|
Comparison
of measurement
|
Remarks
and Recommendation
|
Monitoring Station
|
Easting
(m)
|
Northing (m)
|
Surface Level
(mPD)
|
S1
|
-0.023
|
-0.012
|
0.165
|
Level continuously increased
|
S2
|
0.008
|
-0.004
|
0.100
|
Level continuously increased
|
S3
|
0.000
|
0.000
|
0.107
|
Level continuously increased
|
S4
|
-0.011
|
0.005
|
0.185
|
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 Water
quality monitoring in San Tau (monitoring station SR3(N)) was conducted in
March 2023 as part of mudflat monitoring. The monitoring parameters included
dissolved oxygen (DO), turbidity and suspended solids (SS).
3.6.5 The
water monitoring result for SR3(N) were extracted and summarised in Table
3.10:
Table 3.10 Impact Water Quality Monitoring Results
(Depth Average) at Station SR3(N)
Date
|
Mid Ebb Tide
|
Mid Flood Tide
|
DO (mg/L)
|
Turbidity (NTU)
|
SS (mg/L)
|
DO (mg/L)
|
Turbidity (NTU)
|
SS (mg/L)
|
1-Mar-2023
|
6.57
|
3.55
|
1.85
|
6.35
|
3.55
|
4.80
|
3-Mar-2023
|
6.53
|
3.53
|
6.13
|
6.09
|
3.45
|
4.90
|
6-Mar-2023
|
6.37
|
4.03
|
5.05
|
6.83
|
3.68
|
3.05
|
8-Mar-2023
|
6.83
|
3.68
|
2.48
|
6.37
|
4.03
|
4.05
|
10-Mar-2023
|
7.11
|
3.80
|
4.68
|
6.65
|
4.20
|
3.63
|
13-Mar-2023
|
7.02
|
3.45
|
3.33
|
6.46
|
3.63
|
2.78
|
15-Mar-2023
|
7.26
|
4.23
|
2.33
|
6.89
|
4.55
|
3.38
|
17-Mar-2023
|
6.75
|
4.08
|
2.93
|
6.34
|
4.33
|
3.10
|
20-Mar-2023
|
6.45
|
3.70
|
3.05
|
6.09
|
3.83
|
3.08
|
22-Mar-2023
|
6.20
|
3.95
|
5.68
|
5.90
|
3.90
|
3.85
|
24-Mar-2023
|
6.52
|
3.10
|
7.93
|
6.20
|
3.25
|
7.58
|
27-Mar-2023
|
6.61
|
3.58
|
3.25
|
6.35
|
3.53
|
3.13
|
29-Mar-2023
|
6.40
|
3.50
|
3.10
|
6.24
|
3.43
|
2.63
|
31-Mar-2023
|
6.54
|
3.75
|
2.95
|
6.32
|
3.63
|
3.58
|
Average
|
6.65
|
3.71
|
3.91
|
6.36
|
3.79
|
3.82
|
Mudflat Ecology Monitoring
Sampling Zone
3.6.6 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 in 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 in Appendix O). Survey of horseshoe crabs, seagrass beds and
intertidal communities were conducted in every sampling zone. The present
survey was conducted in March 2023 (totally 4 sampling days 23rd (for ST), 24th
(for TC3), 25th (for TC2) and 26th (for TC1).
3.6.7 Since the field survey of June 2016,
increasing number of trashes and even big trashes (Figure 2.3 in 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 governmental agency units.
Horseshoe Crabs
3.6.8 Active search method was adopted 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 hour 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 23rd (for ST), 24th (for TC3), 25th
(for TC2) and 26th (for TC1) Mar 2023, which were cloudy days.
3.6.9 In
June 2017, a big horseshoe crab was tangled by a trash gill net in ST mudflat (Figure
2.3 in 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 governmental agency units.
Seagrass Beds
3.6.10 Active search method was adopted 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 23rd
(for ST), 24th (for TC3), 25th (for TC2) and 26th
(for TC1) Mar 2023, which were cloudy days.
Intertidal Soft Shore
Communities
3.6.11 The intertidal soft shore community surveys were
conducted in low tide period on on 23rd (for ST), 24th
(for TC3), 25th (for TC2) and 26th (for TC1) Mar 2023. In
every sampling zone, three 100m horizontal transect lines were laid at high
tidal level (H: 2.0m above C.D.), mid tidal level (M: 1.5m above C.D.) and low
tidal level (L: 1.0m above C.D.). Along every horizontal transect line; ten
random quadrats (0.5 m x 0.5m) were placed.
3.6.12 Inside a quadrat, any visible epifauna was collected
and was 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 was collected
and identified. Finally, the top 5 cm surface sediment 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 were 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¡¦= -£U ( 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 ith species.
Mudflat Ecology Monitoring Results and
Conclusion
Horseshoe Crabs
3.6.16 In total of 12 individuals of Carcinoscorpius rotundicauda and Tachypleus
tridentatus were found in present survey. The recorded individuals were
mainly distributed along the shoreline in ST and TC3. All 12 findings were
juveniles specimens. Photo records of previously observed horseshoe crab
is shown in Figure 3.1 of Appendix
O and the present
survey result regarding horseshoe crab are presented in Table 3.1 fo Appendix O. The complete survey records are presented in Annex
II of Appendix
O.
3.6.17 For Carcinoscorpius rotundicauda, 1
individual was found in ST with body size 56.66 mm. In TC3, 4 individuals with
average body size 51.46mm (prosomal width ranged 44.18 ¡V 59.21mm) were found in
present survey. The search record in ST (0.17 ind. hr-1. Person-1) and TC3
(0.67 ind. hr-1. Person-1) were very low. No Carcinoscorpius rotundicauda
was recorded in TC1 and TC2 in present survey.
3.6.18 For Tachypleus tridentatus, 5
individuals with average body size 63.47 mm (prosomal width ranged 51.28 ¡V
79.15 mm) were found in ST and 2 individuals with average body size 60.73
(prosomal width ranged 60.22 ¡V 61.23 mm) were found in TC3 in present survey.
The search records in ST (0.83 ind. hr-1. Person-1) and in TC3 (0.33 ind. Hr-1.
Person-1) was very low. No Tachypleus tridentatus was found in TC1 and
TC2 in present survey.
3.6.19 In the survey of March 2015, there was one
important finding that a mating pair of Carcinoscorpius rotundicauda was
found in ST (prosomal width: male 155.1mm, female 138.2mm). It indicated the
importance of ST as a breeding ground of horseshoe crab. In June 2017, mating
pairs of Carcinoscorpius rotundicauda were 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 December 2017 and June 2018, one mating pair was of Carcinoscorpius
rotundicauda was found in TC3 (December 2017: male 127.80 mm, female 144.61
mm; June 2018: male 139 mm, female 149 mm). In June 2019, two mating pairs of Tachypleus
tridentatus with large body sizes (male 150mm and Female 200mm; Male
180mm and Female 220mm) were found in TC3. Another mating pair of Tachypleus
tridentatus was found in ST (male 140mm and Female 180mm). In March
2020, a pair of Tachypleus tridentatus with large body sizes
(male 123mm and Female 137mm was recorded in TC1. Figure 3.2 of Appendix O shows the photographic records of the mating
pair 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. A mating pair was
found in TC1 in March 2020, it 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 (March ¡V September) because
tiny individuals (i.e. newly hatched) were usually recorded in June and
September every year (Figure 3.2 of Appendix O). One mating pair was found in June 2022.
3.6.20 3 adult individuals (prosomal width >100mm)
of Carcinoscorpius rotundicauda were recorded in September 2022 survey,
with one alive, one dead in TC3 and one dead in TC2. In June 2022, 7 large
individuals (prosomal width >100mm) of Carcinoscorpius rotundicauda was
recorded (prosomal width ranged 131.4mm - 140.3mm) in TC3. In December 2018,
one large individual of Carcinoscorpius rotundicauda was found in TC3
(prosomal width 148.9 mm). In March 2019, 3 large individuals (prosomal width
ranged 220 ¡V 310mm) of Carcinoscorpius rotundicauda were observed in
TC2. In June 2019, there were 3 and 7 large individuals of Tachypleus
tridentatus recorded in ST (prosomal width ranged 140 ¡V 180mm) and TC3
(prosomal width ranged 150 ¡V 220mm), respectively. In March 2020, a mating pair
of Tachypleus tridentatus was recorded in TC1 with prosomal width 123 mm
and 137mm. Base 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. The photo records of the large horseshoe
crab are shown in Figure 3.4 of Appendix
O. 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.
3.6.21 Some marked individuals were found in the
previous surveys of September 2013, March 2014, and September 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¡¦s population might be
restored in the natural habitat. Through a personal conversation with Prof.
Shin, about 100 individuals were released in the sampling zone ST on 20 June
2013. All of them were marked with color tape and internal chip detected by
specific chip sensor. There should be second round of release between June and
September 2014 since new marked individuals were found in the survey of
September 2014.
3.6.22 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
3.6.23 Figure 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 in respectively in
each sampling zone throughout the monitoring period.
3.6.24 To consider the entire monitoring period for
TC3 and ST, medium to high search records (i.e. number of individuals) of both
species (Carcinoscorpius rotundicauda and Tachypleus tridentatus)
were usually found in wet season (June and September). The search record of ST
was higher from September 2012 to June 2014 while it was replaced by TC3 from
September 2014 to June 2015. The search records were similar between two
sampling zones from September 2015 to June 2016. In September 2016, the search
record of Carcinoscorpius rotundicauda in ST was much higher than TC3.
From March to June 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 September 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 June and September
2017, to be discussed in 'Seagrass survey' section). From December 2017 to
September 2018, the search records of both species increased again to
low-moderate level in ST and TC3. From December 2018 to September 2019, the
search records of Carcinoscorpius rotundicauda change from very low to
low while the change of Tachypleus tridentatus was similar during this
period. Relatively higher population fluctuation of Carcinoscorpius
rotundicauda was observed in TC3. From March 2020 to September 2020, the
search records of both species, Carcinoscorpius rotundicauda and
Tachypleus tridentatus, were increased to moderate level in ST. However,
the search records of both species, Carcinoscorpius rotundicauda and
Tachypleus tridentatus, were decreased from very low to none in TC3 in this
period. From March 2021 to September 2021, the search records of both species, Carcinoscorpius
rotundicauda and Tachypleus tridentatus, were kept at low-moderate
level in both ST and TC3. It is similar to the previous findings of June. It
shows another growing phenomenon of horseshoe crabs and it may due to the
weather variation of starting of wet season. The survey results were different
from previous findings that there were usually higher search records in
September. One possible reason was that September of 2021 was one of the
hottest month in Hong Kong in record. As such, hot and shiny weather decreased
horseshoe crab activity. In December 2021, no juvenile was recorded similar to
the some previous in December due to the season. In March 2022, only juvenils
recorded in both ST and TC3, no adult specimen was observed. In June 2022,
total of 13 individuals of Carcinoscorpius rotundicauda and Tachypleus
tridentatus were found, with 6 juveniles, 6 adults and 1 died recorded. In
September 2022, total of 7 individuals of were found, with 4 juveniles, 3
adults (1 alive and 2 died) recorded. In March 2023, total of 12 individuals of
juveniles Carcinoscorpius rotundicauda and Tachypleus tridentatus
were found and recorded.
3.6.25 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 June 2016.
3.6.26 About the body size, larger individuals of Carcinoscorpius
rotundicauda were usually found in ST and TC1 relative to that in TC3 from
September 2012 to June 2017. But the body size was higher in TC3 and ST
followed by TC1 from September 2017 to March 2020. From June 2020 to December
2020, there was no individuals of Carcinoscorpius rotundicauda recorded
in TC3 but in ST. The body size of Carcinoscorpius rotundicauda in ST
was recorded gradually increased (from mean prosomal width 23.6mm to 49.6mm)
since March 2020 to September 2020. From December 2020 to March 2021, the body
size of Carcinoscorpius rotundicauda in ST was recorded decreased (from
mean prosomal width 49.6mm to 43.3mm). In March 2021, the body size of Carcinoscorpius
rotundicauda in TC3 (mean prosomal width 46.2mm) was recorded larger than
that in ST (mean prosomal width 43.3mm). From September 2021 to June 2022, the
body size of Carcinoscorpius rotundicauda in ST was recorded increased
(from mean prosomal width 39.8mm to 54.42mm).
3.6.27 For Tachypleus tridentatus, larger
individuals were usually found in ST and TC3 followed by TC1 throughout the
monitoring period. In June 2019, all found horseshoe crabs were large
individuals and mating pairs. It is believed that the sizes of the horseshoe crabs
would be decrease and gradually rise afterward due to the stable growth of
juveniles after the
spawning season. From March 2019 to September 2021, Tachypleus tridentatus were
only recorded in TC3 and ST. The body size in TC3 was increased from September
2019 to December 2019 then decreased in March 2020 and no recorded species in
TC3 for three consecutive quarters from June 2020 to December 2020. From March
2020 to Sep 2021, the body size of Tachypleus tridentatus in TC3
increased (from mean prosomal width 34.00mm to 38.8mm). It showed a natural
variation of horseshoe crab population in TC3. Apart from natural mortality,
migration from nursery soft shore to subtidal habitat was another possible
cause. The body size in ST was gradually growth since December 2019 to
September 2020 then slightly dropped in December 2020. In June 2022, Tachypleus
tridentatus were only recorded in ST, the body size in ST decreased from
mean prosomal width 77.59mm to 54.02mm in March 2022. In September 2022 Tachypleus
tridentatus were only recorded in TC3. The mean prosomal was 61.09mm. In
March 2023, 7 Tachypleus tridentatus were recorded in ST and TC3. The
mean prosomal was 62.68mm.
3.6.28 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 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 there were
mating pairs seldomly found in TC1 and TC2, the hatching rate and survival rate
of newly hatched individuals were believed very low.
Seasonal variation
of horseshoe crab population
3.6.29 Throughout the monitoring period, the search
records of horseshoe crabs were fluctuated and at moderate ¡V very low level in
June (Figure 3.5 and 3.6 of Appendix O). Low ¡V Very low search record was found in
June 2013, totally 82 individuals of Tachypleus tridentatus and 0 ind. of
Carcinoscorpius rotundicauda were found in TC1, TC3 and ST. Compare with the
search record of June 2013, the numbers of Tachypleus tridentatus were
gradually decreased in June 2014 and 2015 (55 ind. in 2014 and 18 ind. in
2015); the number of Carcinoscorpius rotundicauda raise to 88 and 66 ind. in
June 2014 and 2015 respectively. In June 2016, the search record increased
about 3 times compare with June 2015. In total, 182 individuals of
Carcinoscorpius rotundicauda and 47 individuals of Tachypleus tridentatus were
noted, respectively. Then, the search record was similar to June 2016. The
number of recorded Carcinoscorpius rotundicauda (133 ind.) slightly dropped in
June 2017. However, that of Tachypleus tridentatus rapidly increased (125
ind.). In June 2018, the search record was low to moderate while the numbers of
Tachypleus tridentatus dropped sharply (39 ind.). In June 2019, 10 individuals
of Tachypleus tridentatus were observed in TC3 and ST. All of them, however,
were large individuals (prosomal width >100mm), their records are excluded
from the data analysis to avoid mixing up with the juvenile population living
on intertidal habitat. Until September 2020, the number of Carcinoscorpius
rotundicauda and Tachypleus tridentatus gradually increased to 39 ind. and 28
ind., respectively. In December 2020, the number of Carcinoscorpius
rotundicauda and Tachypleus tridentatus greatly decreased to 3 ind. and 7 ind.,
respectively. In March 2022, the number of Carcinoscorpius rotundicauda and
Tachypleus tridentatus gradually decreased to 7 ind. and 2 ind., respectively
in comparing with the March of previous record. The drop of abundance may be
related to the unusual cold weather in the beginning of March 2022. Throughout
the monitoring period, similar distribution of horseshoe crab population was
found.
3.6.30 The search record of horseshoe crab declined
obviously in all sampling zones during dry season especially December (Figure
3.5 and 3.6 of Appendix
O) throughout the
monitoring period. Very low ¡V low search record was found in December from 2012
to 2015 (0-4 ind. of Carcinoscorpius rotundicauda and 0 ¡V 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). Compare with the search record of December from 2012 to 2015, which
of December 2016 were much higher relatively. There were totally 70 individuals
of Carcinoscorpius rotundicauda and 24 individuals of Tachypleus tridentatus in
TC3 and ST. Since the survey was carried in earlier December with warm and
sunny weather (~22 ºC during dawn according to Hong Kong Observatory database,
Chek Lap Kok station on 5 December 2016), the horseshoe crab was more active
(i.e. move onto intertidal shore during high tide for foraging and breeding)
and easier to be found. 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„aC during dawn on 19 December). The
horseshoe crab activity would decrease gradually with the colder climate. In
December of 2017, 2018 and 2019, very low search records were found again as
mentioned above. No record of houseshoe crab was recorded in December 2022.
3.6.31 From September 2012 to December 2013,
Carcinoscorpius rotundicauda was less common species relative to Tachypleus
tridentatus. Only 4 individuals were ever recorded in ST in December 2012. This
species had ever been believed of very low density in ST hence the encounter
rate was very low. In March 2014, it was found in all sampling zones with
higher abundance in ST. Based on its average size (mean prosomal width 39.28 ¡V
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 March 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
March to September). 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
March and June 2014 and followed by a rapid decline in September 2014. Then the
number of individuals fluctuated slightly in TC3 and ST until March 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 March 2014. Then it
varied slightly between 35-65 mm from September 2014 to March 2017.Most of the
individuals might have reached a suitable size (e.g. prosomal width 50 ¡V 60 mm)
strong enough to forage in sub-tidal habitat. In June 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
September 2017, moderate numbers of individual were found in TC3 and ST
indicating a stable population size. From September 2018 to March 2020, the
population size was low while natural mortality was the possible cause. From
June 2020 to September 2020, the population size of Tachypleus tridentatus
increased to moderate level in ST while the mean proposal width of them
conitued to grow and reach about 55mm. The population size of Tachypleus
tridentatus slightly decreased in ST from March 2021 to March 2022 and the mean
proposal width of them increased to about 77.59mm.
3.6.33 In recent year, the 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, the number of Tachypleus
tridentatus increased in ST. 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 September 2012 and
December 2013 hence the data were lacking. In March 2014, the major size (50%
of individual records between upper (top box) and lower quartile (bottom box))
ranged 40 ¡V 60 mm while only few individuals were found. From March 2014 to
September 2018, the median prosomal width (middle line of whole box) and major
size (whole box) decreased after March 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 June to March 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 ¡V 90 mm)
along the sampling months. Juveniles reaching this size might gradually migrate
to sub-tidal habitats. In March 2022, 2 Carcinoscorpius rotundicauda with body
size (prosomal width 52.21-54.63mm) were found in TC3. The findings were
relatively lower than the previous record in March. This can due to the natural
variation caused by multi-environmental factors.
3.6.35 For Tachypleus tridentatus, the major size
ranged 20-50 mm while the number of individuals fluctuated from September 2012
to June 2014. Then a slight but consistent growing trend was observed from
September 2014 to June 2015. The prosomal width increased from 25 ¡V 35 mm to 35
¡V 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 March to September 2016, slight increasing
trend of major size was noticed again. From December 2016 to June 2017, similar
increasing trend of major size was noted with much higher number of
individuals. It reflected new round of spawning. In September 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 June and September
2017 (to be discussed in the 'Seagrass survey' section). From December 2017 to
September 2018, increasing trend was noted again. It indicated a stable growth
of individuals. From September 2018 to that of next year, the average prosomal
widths were decreased from 60mm to 36mm. It indicated new rounds of spawning
occurred during September to November 2018. In December 2019, an individual
with larger body size (prosomal width 65mm) was found in TC3 which reflected
the stable growth of individuals. In March 2020, the average prosomal width
(middle line of the whole box) of Tachypleus tridentatus in TC3 was 33.97mm
which is smaller than that in December 2019. It was in normal fluctuation. From
June 2020 to December 2020, no horseshoe crab was recorded in TC3. In Sep 2021,
only one Tachypleus tridentatus with body size (prosomal width 38.78mm) was
found in TC3. The decrease in the species population was considered to be related
to hot weather in September, which may affect their activity. Across the whole
monitoring period, the larger juveniles (upper whisker) usually reached 60 ¡V 80
mm in prosomal width, even 90 mm occasionally. The 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 September 2012 and
December 2013 hence the data were lacking. From March 2014 to September 2018,
the size of major population decreased and more small individuals (i.e. lower
whisker) were recorded after June of every year. It indicated new round of
spawning. Also there were similar increasing trends of body size from September
to June of next year between 2014 and 2017. It indicated a stable growth of
individuals. The larger juveniles (i.e. upper whisker usually ranged 60 ¡V 80 mm
in prosomal width except one individual (prosomal width 107.04 mm) found in
March 2017. It reflected juveniles reaching this size would gradually migrate
to sub-tidal habitats.
3.6.37 For Tachypleus tridentatus, a consistent
growing trend was observed for the major population from December 2012 to
December 2014 regardless of change of search record. The prosomal width
increased from 15 ¡V 30 mm to 60 ¡V 70 mm. As mentioned, the large juveniles
might have reached a suitable size for migrating from the nursery soft shore to
subtidal habitat. From March to September 2015, the size of major population
decreased slightly to a prosomal width 40 ¡V 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 December 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 March 2016, the number of
individual was very few in ST that no box plot could be produced. In June 2016,
the prosomal width of major population ranged 50 ¡V 70 mm. But it dropped
clearly to 30 ¡V 40 mm in September 2016 followed by an increase to 40 ¡V 50 mm
in December 2016, 40 ¡V 70 mm in March 2017 and 50 ¡V 60mm in June 2017. Based on
overall higher number of small individuals from June 2016 to September 2017, it
indicated another round of spawning. From September 2017 to June 2018, the
major size range increased slightly from 40 ¡V 50 mm to 45 ¡V 60 mm indicating a
continuous growth. In September 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 ground 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.
3.6.39 In March 2019 to June 2019 and Dec 2021, no
horseshoe crab juveniles (prosomal width <100mm) were recorded in TC3 and
ST. All recorded horseshoe crabs were large individuals (prosomal width
>100mm) or mating pairs which were all excluded from the data analysis. From
September 2019 to September 2020, the population size of both horseshoe crab
species in ST gradually increased to moderate level while their body sizes were
mostly in small to medium range (~23 ¡V 55mm). It indicated the natural stable
growth of the horseshoe crab juveniles. In December 2020, the population size
of both horseshoe crab species in ST dropped to low level while their body
sizes were mostly in small to medium range (~28 ¡V 56mm). It showed the natural
mortality and seasonal variation of horseshoe crab. In June 2022, the
population size of both horseshoe crab species in ST was kept as low-moderate
level while their body sizes were mostly in small to medium range (~51¡V78mm).
In September 2022, the population size of both horseshoe crab species in TC3
and ST was kept as low-moderate level while their body sizes were mostly in
small to medium range (~56¡V62mm). In September 2022, the population size of
both horseshoe crab species in TC3 and ST was kept as low-moderate level while
their body sizes were mostly in small to medium range (~44-79mm).
Impact of the HKLR project
3.6.40 It was the 43rd survey of the EM&A
programme during construction period. Based on the monitoring results, no
detectable impact on horseshoe crab was revealed due to HKLR project. The
population change was mainly determined by seasonal variation, no abnormal
phenomenon of horseshoe crab individual, such as large number of dead
individuals on the shore had been reported.
Seagrass Beds
3.6.41 Two seagrass species Halophila ovalis and
Zostera japonica were found in present survey. Halophila ovalis was found in
TC3 and ST and Zostera japonica was found only in ST. In ST, there were six
large sized of Halophila ovalis found at tidal zone 1.5m above C.D nearby
mangroves plantation. The larger strand had area ~7200m2 in moderate vegetation
coverage (40-50%), ~4500m2 in moderate vegetation coverage (30 - 40%),~1500m2
in moderate vegetation coverage (20 - 30%) and three ~500 - 150m2 in low to
moderate vegetation coverage (10 - 30%). In TC3, 3 large patches of Halophila
ovalis were found at tidal zone 1.5m above C.D. The larger strand had area
~1800m2 in moderate vegetation coverage (40 - 70%), ~1500m2 in moderate
vegetation coverage (30 - 60%) and ~600m2 in moderate vegetation coverage
(20-50%). At close vicinity to mangrove, one small sized (5m2) of Zostera
japonica beds were observed at tidal zone 2.0m above C.D in ST. Table 3.2
of Appendix
O summarizes the
results of present seagrass beds survey and the photograph records of the
seagrass are shown on Figure 3.9 of Appendix O. The complete record throughout the monitoring
period is presented in Annex III of Appendix O .
3.6.42 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 3.10 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 ¡V 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 co-existed with Halophila
ovalis nearby the mangrove strand at 2.0 m above C.D.
3.6.43 According to the previous results, majority of
seagrass bed was confined in ST, the temporal change of both seagrass species
was investigated in details:
Temporal variation of seagrass beds in ST
3.6.44 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 March 2013 that
grew within the large patch of seagrass Halophila ovalis. Then, the patch size
increased and merged gradually with the warmer climate from March to June 2013
(15 m2). However the patch size decreased and remained similar from September
2013 (4 m2) to March 2014 (3 m2). In June 2014, the patch size increased
obviously again (41 m2) with warmer climate followed by a decrease between
September 2014 (2 m2) and December 2014 (5 m2). From March to June 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 September 2015 to June
2016, it was found coexisting with seagrass Halophila ovalis with steady
increasing patch size (from 44 m2 to 115 m2) and variable coverage. In
September 2016, the patch size decreased again to (38 m2) followed by an
increase to a horizontal strand (105.4 m2) in June 2017. And it did no longer
co-exist with Halophila ovalis. Between September 2014 and June 2017, an
increasing trend was noticed from September to June of next year followed by a
rapid decline in September 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 September 2017 to March 2021, while no
patch of Zostera japonica was found. From June 2021, the species was recorded
again in area of 45m2. The recorded area of the seagrass bed in September 2021
survey was slightly decreased to 15m2.
3.6.45 For Halophila ovalis, it was recorded as 3 ¡V 4
medium to large patches (area 18.9- 251.7 m2; vegetation coverage 50 ¡V 80%)
beside the mangrove vegetation at tidal level 2 m above C.D. in September 2012.
The total seagrass bed area grew steadily from 332.3 m2 in September 2012 to
727.4 m2 in December 2013. Flowers were observed in the largest patch during
its flowering period. In March 2014, 31 small to medium patches were newly
recorded (variable area 1 ¡V 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 June 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 ¡V 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 September 2014, the
total seagrass area declined sharply to 1111m2. There were only 3-4 small to
large patches (6 ¡V 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 September 2014, there were two tropical cyclone records in Hong Kong
(7th ¡V 8thSeptember: no cyclone name, maximum signal number 1; 14th ¡V 17th
September: Kalmaegi, maximum signal number 8SE) before the seagrass survey
dated 21st September 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 ¡V 20%) and small leaves.
3.6.46 In December 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 June 2014
and December 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).
Unfavorable conditions to seagrass Halophila ovalis
3.6.47 Typhoon or strong water current was suggested
as one unfavorable condition to Halophila ovalis (Fong, 1998). As mentioned
above, there were two tropical cyclone records in Hong Kong in September 2014.
The strong water current caused by the cyclones might have given damage to the
seagrass beds.
3.6.48 Prolonged light deprivation due to turbid water
would be another unfavorable condition. Previous studies reported that
Halophila ovalis had little tolerance to light deprivation. During experimental
darkness, seagrass biomass declined rapidly after 3-6 days and seagrass died completely
after 30 days. The rapid death might be due to shortage of available
carbohydrate under limited photosynthesis or accumulation of phytotoxic end
products of anaerobic respiration (details see Longstaff et al., 1999). Hence
the seagrass bed of this species was susceptible to temporary light deprivation
events such as flooding river runoff (Longstaff and Dennison, 1999).
3.6.49 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 September 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 ¡V 25.3 NTU and
22.3 ¡V 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 September 2014 (daily total rainfall at the Hong Kong
International Airport: 0 ¡V 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, was 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.
3.6.50 Based on the weather condition and water
quality results in ST, the co-occurrence of cyclone hit and turbid waters in
September 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 in the mudflat of ST through
seed reproduction as long as there was no unfavourable condition in the coming
months.
Recolonization of seagrass beds
3.6.51 Figure 3.12 of Appendix O shows the recolonization of seagrass bed in ST
from December 2014 to June 2017. From March to June 2015, 2 ¡V 3 small patches
of Halophila ovalis were newly found co-inhabiting with another seagrass
species Zostera japonica. But the total patch area of Halophila ovalis was
still very low compare with previous records. The recolonization rate was low
while cold weather and insufficient sunlight were possible factors between
December 2014 and March 2015. Moreover, it would need to compete with seagrass
Zostera japonica for substratum and nutrient, because Zostera japonica had
extended and covered the original seagrass bed of Halophila ovalis at certain
degree. From June 2015 to March 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 its competitor Zostera japonica. In June 2016, the
total seagrass area increased sharply to 4707.3m2. Similar to the previous
records of March to June 2014, the original patch area of Halophila ovalis
increased further to a horizontally long strand. Another large seagrass beds
colonized the lower tidal zone (1.0 ¡V 1.5 m above C.D.). In September 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 December 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 March to
June 2017, the seagrass bed area remained generally stable (12438- 17046.5 m2)
but the vegetation coverage fluctuated (20 ¡V 50% in March 2017 to 80 ¡V 100% in
June 2017). The whole recolonization process took about 2.5 years.
Second disappearance of seagrass bed
3.6.52 In September 2017, the whole seagrass bed of
Halophila ovalis disappeared again along the shore of TC3 and ST (Figure
3.12 of Appendix
O). Similar to the
first disappearance of seagrass bed occured between September and December
2014, strong water current (e.g. cyclone) or deteriorated water qualities (e.g.
high turbidity) was the possible cause.
3.6.53 Between the survey periods of June and
September 2017, there were four tropical cyclone records in Hong Kong (Merbok
in 12- 13th, June; Roke in 23rd, Jul.; Hato in22 ¡V 23rd, Aug.; Pakhar in 26 ¡V
27th, Aug.) (Online database of Hong Kong Observatory) All of them reached
signal 8 or above, especially Hato with highest signal 10.
3.6.54 According to the water quality monitoring
results (July to August 2017) of the two closest monitoring stations SR3 and
IS5 of the respective EM&A programme, the overall water quality was in
normal fluctuation. There was an exceedance of suspended solids (SS) at SR3 on
12 July 2017. The SS concentration reached 24.7 mg/L during mid-ebb tide, which
exceeded the Action Level (≤ 23.5 mg/L). But it 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.
3.6.55 Overall, the disappearance of seagrass beds in
ST has believed the cause of serial cyclone hit in July and August 2017. Based
on previous findings, the seagrass beds of both species were expected to
recolonize in the mudflat as long as the vicinal water quality was normal. The
whole recolonization process (from few, small patches to extensive strand)
would be gradually lasting at least 2 years. From December 2017 to March 2018,
there was still no recolonization of few, small patches of seagrass at the
usual location (Figure 3.12 of Appendix
O). It was
different from the previous round (March 2015 ¡V June 2017). Until June 2018,
the new seagrass patches with small-medium size 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 September 2018. Again it was believed that the decrease was due to the hit
of the super cyclone in September 2018 (Mangkhuton 16th September, highest
signal 10). From December 2018 to June 2019, the seagrass bed area increased
from 404 m2 to 1229 m2 while the vegetation coverage is also increased
(December 2018: 5¡V 85%; March 2019: 50 ¡V 100% and June 2019: 60 ¡V 100%).
Relatively, the whole recolonization process would occur slower than the
previous round (more than 2 years). From September 2019 to March 2021, the
seagrass bed area in ST slightly decreased from 1200 m2 to 942.05 m2, which
were in normal fluctuation. From March 2021 to December 2021, the seagrass bed
area in ST decreased from 942.05 m2 to 680m2, which were in normal fluctuation.
In March 2022, the seagrass bed area in ST increased significantly to
approximately 2040 m2, which believed to be related to more rain in current dry
season. It was observed that the brown filemental algae bloom occurred at ST
site in March 2022. Distribution of the algae was overlap with seagrass beds,
mainly the species Halophila ovalis and the algae was grown over the top of the
seagrass. In some areas, the brown filemental algae full covered the seagrass
bed, refer to Figure 3.9 of Appendix
O. The seagrass was
still alive when checked during the field survey. Whether the algae bloom will
kill seagrass in longer period time is unknown. The seagrass distritrution and
health condition should be checked in coming June monitoring. The algae bloom
of the brown filemental algae at the seagrass bed is disappeared as observed in
June 2022, refer to Figure 3.9 of Appendix O. Seagrass in December 2022 and September 2022
have decreased compare to June 2022 due to normal seasonal change. Seagrass in
March 2023 have increased compare to previous quarter due to normal seasonal
change.
Impact of HKLR project
3.6.56 It was the 43rd survey of the EM&A programme during construction
period. Throughout the monitoring period, the disappearance of seagrass beds
was believed the cause of cyclone hits rather than impact of HKLR project. The
seagrass bed was recolonizing since there had been a gradual increase in the
size and number from December 2018 to June 2019 after the hit of the super
cyclone in September 2018. The seagrass bed area decreased from March 2021 to
December 2021, which were in normal fluctuation. It is observed that the
seagrass Halophila ovalis covered larger area than before. Total seagrass bed
area significantly increased from March 2022 to June 2022 and slightly reduced
in September 2022. Seagrass in March 2023 have increased compare to previous
quarter due to normal seasonal change.
Intertidal Soft
Shore Communities
Substratum
3.6.57 Table 3.4 of Appendix O lists the total abundance, density and number of taxon
of every phylum in this survey. A total of 8469 individuals were recorded.
Mollusca was the most abundant phylum (total abundance 7607 ind., density 254
ind. m-2, relative abundance 89.8%). The second and third were Arthropoda
(582ind., 20 ind. m-2, 6.9%) which followed by Annelida (126 ind., 4 ind. m-2,
1.5%) and Sipuncula (84 ind., 3 ind. m-2, 1.0%), respectively. The fifth was
Nemertea with total abundance 42 ind., density 1 ind.m-2 and relative abundance
0.5%. The sixth was Cnidania with total abundance 27 ind., density 1 ind.m-2
and relative abundance 0.3%.Platyhelminthes was very low in abundances (density
<0 ind. m-2, relative abundance „T0.0%). Moreover, the most diverse phylum was
Mollusca (32 taxa) followed by Arthropoda (6 taxa). Annelida (3 taxa) and
Sipuncula (2 taxa). There was 1 taxon for Nemertea, Cnidaria and
Platyhelminthes.
3.6.58 The taxonomic resolution and complete list of
recorded fauna are shown in Annex IV and V of Appendix O respectively. As reported in June 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:
¡P Cerithidea cingulata was revised as Pirenella
asiatica
¡P Cerithidea djadjariensis was revised as
Pirenella incisa
¡P Cerithidea rhizophorarum was revised as
Cerithidea moerchii
3.6.59 Moreover, taxonomic revision was conducted on
another snail species while the specie name was revised:
¡P Batillaria bornii was revised as Clypeomorus
bifasciata
3.6.60 In March 2021, an increased number of sea slugs
and their eggs were observed in all sampling zones. It may due to the breeding
season of sea slug and the increased of algae on the intertidal.
3.6.61 Table 3.5 of Appendix O shows the number of individuals, relative
abundance and density of each phylum in every sampling zone. The total
abundance (1,728 - 2,333 ind.) varied among the four sampling zones while the
phyla distributions were similar. In general, Mollusca was the most dominant
phylum (no. of individuals: 1,588 - 2,141 ind.; relative abundance 83.9 ¡V 1.9%;
density 212 - 285 ind. m-2). Other phyla were much lower in number of
individuals. Arthropoda (89 - 306 ind.; 4.0 ¡V 14.3%; 12 - 41 ind. m-2) was
common phyla relatively. Other phyla were very low in abundance in all sampling
zones.
Dominant
species in every sampling zone
3.6.62 Table 3.6 of Appendix O lists the abundant species in every sampling zone. In
the present survey, most of the listed abundant species were of high or very
high density (>100 ind. m-2), which were regarded as dominant species. Few
of the listed species were of low to moderate densities (42 ¡V 95 ind. m-2).
Other listed species of lower density (<42 ind. m-2) were regarded as common
species.
3.6.63 In TC1, the substratum was mainly ¡¥Gravels and
Boulders¡¦ at high and mid tidal levels. At high tidal level, the rock oyster
Saccostrea cucullata (mean density 108 ind. m-2; relative abundance 41%) was
the dominant species found at moderate density and the gastropod Monodonta
labio (70 ind. m-2; relative abundance 27%) was of low to moderate density. At
mid tidal level, the rock oyster Saccostrea cucullata (73 ind. m-2, 38%) was at
dominant species with low to moderate density. The gastropod Monodonta labio
(37 ind. m-2, 20%) was at lower density. At low tidal level (main substratum
type ¡¥Soft mud¡¦), the Batillaria multiformis (53 ind. m-2, 22%) was dominant at
low to moderate densities, the Barbatia virescens (42 ind. m-2, 17%) and
Nodilittorina radiata (34 ind. m-2, 14%) were of lower density, regarded as
common species.
3.6.64 In TC2, the substratum types were mainly '
Gravels and Boulders' at high tidal level. The rock oyster Saccostrea
cucullata (132 ind. m-2, 40%) was dominant at high density. The gastropod
Monodonta labio (55 ind. m-2, 17%) was dominant at low to moderate density. At
mid tidal level (main substratum types ¡¥Soft mud¡¦ and ¡¥Gravels and Boulders¡¦),
rock oyster Saccostrea cucullata (92 ind. m-2, 29%), gastropods Monodonta labio
(51 ind. m-2, 16%) and Batillaria zonalis (44 ind. m-2, 14%) were dominant at
low to moderate densities. Substratum types ¡¥Soft Mud¡¦ were mainly distributed
at low tidal level, the Barbatia virescens (42 ind. m-2, 20%) was dominant at
low to moderate densities, Lunella granulate (21 ind. m-2, 10%), the Batillaria
multiformis (21 ind. m-2, 10%) and Batillaria zonalis (22 ind. m-2, 10%) were of
lower densities, regarded as common species.
3.6.65 In TC3, the substratum type was mainly ¡¥Gravels
and Boulders¡¦ at high tidal level. The rock oyster Saccostrea cucullata (122
ind. m-2, 42%) was of dominant species at high density and the gastropod Monodonta
labio (62 ind. m-2, 21%) was of low to moderate density. At mid tidal level
(main substratum types ¡¥Soft mud¡¦), the rock oyster Saccostrea cucullata (116
ind. m-2, 31%) was of dominant species at high density. The gastropod Monodonta
labio (56 ind. m-2, 15%) was at low density level. At low tidal level, the
major substratum type was ¡¥Soft mud¡¦. The Lunella granulate (44 ind. m-2, 17%),
the Batillaria multiformis (38 ind. m-2, 14%), Batillaria zonalis (36 ind. m-2,
14%) and the Barbatia virescens (34 ind. m-2, 13%) at lower density.
3.6.66 In ST, the major substratum type was ¡¥Gravels
and Boulders¡¦ at high tidal level. At high tidal level, the rock oyster
Saccostrea cucullata (120 ind. m-2, 40%) was abundant at high density. The
gastropods Monodonta labio(54 ind. m-2, 18%) was at low to moderate densities
and Batillaria multiformis (38 ind. m-2, 13%) was at lower desity. At mid tidal
level (main substratum types ¡¥Gravels and Boulders¡¦ and ¡¥Soft mud¡¦), the rock
oyster Saccostrea cucullata (111 ind. m-2, 33%) was the dominant species at
high density, and followed by the gastropod Monodonta labio (62 ind. m-2, 18%)
at low to moderate density. At low tidal level (major substratum: ¡¥Soft mud¡¦),
the Batillaria zonalis (50 ind. m-2, 18%) was at low to moderate demsities and
Lunella granulata (48 ind. m-2, 18%) was at lower density.
3.6.67 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, rock oyster Saccostrea cucullata (874 ind.), gastropods Monodonta
labio (448 ind.) and Batillaria multiformis (150 ind.) were the most common
species on gravel and boulders substratum. Batillaria zonalis (130 ind.) was
the most common species on sands and soft mud substrata.
Biodiversity
and abundance of soft shore communities
3.6.68 Table 3.7 of Appendix O shows the mean values of species number,
density, and 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.
3.6.69 Among the sampling zones, the mean species
number was varied from 14 - 21 spp. 0.25 m-2 among the four sampling zones. The
mean densities of TC3 (311 ind. m-2) was higher than ST (302 ind. m-2) followed
by TC2 (285 ind. m-2) and TC1 (230 ind. m-2). The higher densities of TC3 and
ST are due to the relatively high number of individuals in each quadrat. The
mean H¡¦ for TC2 was 2.23, TC3 was 2.23, TC1 was 2.10 and ST were 2.10, followed
by while the mean J of TC2, TC3 and ST were 0.8, which were slightly higher
than TC1 (0.77). This can be due to the relatively non-even taxa distribution.
3.6.70 In the present survey, no clear trend of mean
species number, mean density, H¡¦ and J observed among the tidal level.
3.6.71 Figures 3.14-3.17 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 (December) but the mean H' and J fluctuated
within a limited range.
3.6.72 From June to December 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 unfavorable change reflecting
environmental stresses. The heat stress and serial cyclone hit were believed
the causes during the wet season of 2017. From March 2018 to March 2023
(present survey), generally increases of mean species number and density were
observed in all sampling zones. It indicated the recovery of intertidal
community.
Impact
of HKLR project
3.6.73 It was the 43rd 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.
3.8
Environmental Licenses and Permits
3.8.1 The
valid environmental licenses and permits during the reporting period are
summarized in Appendix
L.
4
Environmental Complaint
and Non-compliance
4.1
Environmental Exceedances
4.1.1 The detailed air quality, noise,
water quality and dolphin exceedances are provided in Appendix M. Also, the summaries of the environmental
exceedances are presented as follows:
Air Quality
4.1.2 No Action Level and Limit level
exceedances of 1-hr TSP and 24-hr TSP were recorded at AMS5 during the
reporting period.
Noise
4.1.3 No Action/Limit Level exceedances
for noise were recorded during daytime on normal weekdays of the reporting
period.
Water Quality
4.1.4
For marine water quality monitoring, no Action Level
and Limit Level exceedances of dissolved oxygen level, turbidity level and
suspended solid were recorded during the reporting period.
Dolphin
4.1.5
There was a Limit Level
exceedance of dolphin monitoring for the quarterly monitoring data (between
March 2023 and May 2023). According to the contractor¡¦s information, toe
loading removal works were undertaken for HKLR03 during the quarter of March
2023 and May 2023.
4.1.6
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 ¡V
Sham Shui Kok Anchorage (near Brothers Island) as far as practicable.
4.1.7
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.
4.2
Summary of Environmental Complaint, Notification of Summons and
Successful Prosecution
4.2.1 There was no complaint received in
relation to the environmental impacts during this reporting period. The details
of cumulative statistics of Environmental Complaints are provided in Appendix N.
4.2.2 No notification of summons and
prosecution was received during the reporting period. Statistics on
notifications of summons and successful prosecutions are summarized in Appendix M.
5 Comments, Recommendations and
Conclusion
5.1.1 According to the environmental site
inspections undertaken during the reporting period, the following
recommendations were provided:
¡P The Contractor was reminded to maintain the silt
curtains properly at Portion X.
5.2.1 The impact monitoring programme
ensured that any deterioration in environmental condition was readily detected
and timely actions taken to rectify any non-compliance. Assessment and analysis
of monitoring results collected demonstrated the environmental impacts of the
contract. With implementation of the recommended environmental mitigation
measures, the contract¡¦s environmental impacts were considered environmentally acceptable.
The weekly environmental site inspections ensured that all the environmental
mitigation measures recommended were effectively implemented.
5.2.2 The recommended environmental
mitigation measures, as included in the EM&A programme, effectively
minimize the potential environmental impacts from the contract. Also, the
EM&A programme effectively monitored the environmental impacts from the
construction activities and ensure the proper implementation of mitigation
measures. No particular recommendation was advised for the improvement of the
programme.
5.3.1 The construction phase and EM&A
programme of the Contract commenced on 17 October 2012. This is the
forty-second Quarterly EM&A Report which summarizes the monitoring results
and audit findings of the EM&A programme during the reporting period from 1
March 2023 to 31 May 2023.
Air Quality
5.3.2 No Action Level and Limit Level
exceedances of 1-hr TSP and 24-hr TSP were recorded at AMS5 during the
reporting period. The existing air quality monitoring location AMS6 - Dragonair
/ CNAC (Group) Building (HKIA) was handed over to Airport Authority Hong Kong
on 31 March 2021. 1-hr and 24-hr TSP monitoring at AMS6 was temporarily
suspended starting from 1 April 2021.
Noise
5.3.3 No Action/Limit Level exceedances
for noise were recorded during daytime on normal weekdays of the reporting
period.
Water Quality
5.3.4
No exceedances for water quality monitoring
were recorded during the reporting period.
5.3.5
For marine water quality monitoring, no Action Level
and Limit Level exceedances of dissolved oxygen level, turbidity level and
suspended solid were recorded during the reporting period.
Dolphin
5.3.6 There was a Limit Level exceedance
of dolphin monitoring for the quarterly monitoring data between March 2023 to
May 2023.
5.3.7 During this quarter of dolphin
monitoring, no adverse impact from the activities of this construction project
on Chinese White Dolphins was noticeable from general observations.
5.3.8 Although dolphins rarely occurred in
the area of HKLR03 construction in the past and during the baseline monitoring
period, it is apparent that dolphin usage has been significantly reduced in NEL
since 2012, and many individuals have shifted away from the important habitat
around the Brothers Islands.
5.3.9 It is critical to continuously
monitor the dolphin usage in North Lantau region to determine whether the
dolphins are continuously affected by the construction activities in relation
to the HZMB-related works, and whether suitable mitigation measure can be
applied to revert the situation.
Mudflat
- Sedimentation Rate
5.3.10 This measurement result was generally and
relatively higher than the baseline measurement at S1, S2, S3 and S4. The
mudflat level is continuously increased.
Mudflat
- Ecology
5.3.11
The March 2023 survey results indicate that impacts
of the HKLR project were not detected on intertidal soft shore community. Based
on the monitoring results, no detectable impact on horseshoe crab was revealed
due to HKLR project. The population change was mainly determined by seasonal
variation, no abnormal phenomenon of horseshoe crab individual, such as large
number of dead individuals on the shore had been reported. Throughout the
monitoring period, the disappearance of seagrass beds was believed the cause of
cyclone hits rather than impact of HKLR project. The seagrass bed was
recolonizing since there had been a gradual increase in the size and number
from December 2018 to June 2019 after the hit of the super cyclone in September
2018. The seagrass bed area decreased from March 2021 to December 2021, which
were in normal fluctuation. It is observed that the seagrass Halophila
ovalis covered larger area than before. Total seagrass bed area
significantly increased from March 2022 to June 2022 and slightly reduced in
September 2022. Seagrass
in March 2023 have increased compared to previous quarter due to normal
seasonal change.
Environmental Site Inspection and Audit
5.3.12 Environmental site
inspection was carried out on 7, 16, 22 and 31 March 2023; 4, 12, 18, and 28 April
2023; 4, 10, 16, 25 and 31 May 2023. Recommendations on remedial actions were given to the Contractors for
the deficiencies identified during the site inspections.
5.3.13 There was no complaint received in relation to
the environmental impact during the reporting period.
5.3.14
No notification of
summons and prosecution was received during the reporting period.