Contract No.
HY/2011/03
Hong Kong-Zhuhai-Macao Bridge Hong Kong Link Road
Section between Scenic Hill and Hong Kong Boundary Crossing
Facilities
Monthly EM&A Report No.117 (June 2022)
15
August 2022
Revision
1
Main
Contractor Designer
Contents
Executive Summary
1.4 Construction
Works Undertaken During the Reporting Month
2....... Air Quality Monitoring
2.4 Monitoring
Parameters, Frequency and Duration
2.6 Monitoring
Schedule for the Reporting Month
3.4 Monitoring
Parameters, Frequency and Duration
3.6 Monitoring
Schedule for the Reporting Month
4....... Water
Quality Monitoring
4.3 Monitoring
Parameters, Frequency and Duration
4.6 Monitoring
Schedule for the Reporting Month
6.1 Sedimentation
Rate Monitoring
6.3 Mudflat
Ecology Monitoring Methodology
6.4 Event
and Action Plan for Mudflat Monitoring
6.5 Mudflat
Ecology Monitoring Results and Conclusion
7....... Environmental Site
Inspection and Audit
7.2 Advice
on the Solid and Liquid Waste Management Status
7.3 Environmental
Licenses and Permits
7.4 Implementation
Status of Environmental Mitigation Measures
7.5 Summary
of Exceedances of the Environmental Quality Performance Limit
7.6 Summary
of Complaints, Notification of Summons and Successful Prosecution
8.1 Construction
Programme for the Coming Months
8.2 Environmental
Monitoring Schedule for the Coming Month
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 Calibration
Certificates
Appendix D Monitoring Schedule
Appendix E Monitoring Data and
Graphical Plots
Appendix F Event and Action Plan
Appendix G Wind Data
Appendix H Not Used
Appendix I Mudflat Monitoring
Results
Appendix J Waste Flow Table
Appendix K Cumulative Statistics
on Complaints
Appendix L Environmental Licenses and
Permits
Appendix M Implementation Schedule of
Environmental Mitigation Measures
Appendix N Record of ¡§Notification of Summons
and Prosecutions¡¨
Appendix O Location of Works Areas
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 Environmental Impact Assessment (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.
This is the 117th
Monthly 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 to 30 June 2022.
Environmental
Monitoring and Audit Progress
The monthly EM&A programme
was undertaken in accordance with the Updated EM&A Manual for HKLR (Version
1.0). A summary of the monitoring activities during this reporting month is
listed below:
1-hr TSP Monitoring at
AMS5 |
2, 8, 14, 20, 24 and 30
June 2022 |
24-hr TSP Monitoring at
AMS5 |
1, 7, 13, 17, 23 and 29 June 2022 |
Noise Monitoring |
2, 10, 14, 20 and 30 June
2022 |
Water Quality Monitoring |
Not applicable. Water
quality monitoring was temporarily suspended during the reporting month. |
Chinese White Dolphin
Monitoring |
Due to adverse weather
and boat availability, the dolphin monitoring programme was suspended.
Therefore, no dolphin monitoring results are presented during the reporting
month. |
Site Inspection |
8, 14, 22 and 28 June 2022
|
Mudflat Monitoring
(Ecology) |
13, 14,
15 and 16 June 2022
|
Mudflat Monitoring
(Sedimentation Rate) |
13
June 2022
|
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. A new alternative air quality monitoring location
is still under processing. Due to poor weather condition on 8 June 2022, noise
monitoring at NMS5 ¡V Ma Wan Chung Village was rescheduled to 10 June 2022. |
Breaches of Action and Limit Levels
A summary of environmental
exceedances for this reporting month 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) |
N.A. (See Remark 1) |
N.A. (See Remark 1) |
Turbidity level |
N.A. (See Remark 1) |
N.A. (See Remark 1) |
|
Dissolved oxygen level (DO) |
N.A. (See Remark 1) |
N.A. (See Remark 1) |
Remark: 1) Not applicable.
Water quality monitoring was temporarily suspended during the reporting month.
Complaint Log
One complaint was received
in relation to the environmental impacts during this reporting month.
Notifications
of Summons and Prosecutions
There were no
notifications of summons or prosecutions received during this reporting month.
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.
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 - 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.
Future Key
Issues
The future key
issues include potential noise, air quality, water quality and ecological
impacts and waste management arising from the following construction activities
to be undertaken in the upcoming month:
¡P
New reclamation along
the east coast of the approximately 23 hectares.
¡P
Tunnel of Scenic Hill
(Tunnel SHT) from Scenic Hill to the new reclamation, of approximately 1km in
length with three (3) lanes for the east bound carriageway heading to the HKBCF
and four (4) lanes for the westbound carriageway heading to the HZMB Main
Bridge.
¡P
An abutment of the
viaduct portion of the HKLR at the west portal of Tunnel SHT and associated
road works at the west portal of Tunnel SHT.
¡P
An at grade road on
the new reclamation along the east coast of the HKIA to connect with the HKBCF,
of approximately 1.6 km along dual 3-lane carriageway with hard shoulder for
each bound.
¡P
Road links between
the HKBCF and the HKIA including new roads and the modification of existing
roads at the HKIA, involving viaducts, at grade roads and a Tunnel HAT.
¡P
A highway operation
and maintenance area (HMA) located on the new reclamation, south of the Dragonair Headquarters Building, including the construction
of buildings, connection roads and other associated facilities.
¡P
Associated civil,
structural, building, geotechnical, marine, environmental protection,
landscaping, drainage and sewerage, tunnel and highway electrical and
mechanical works, together with the installation of street lightings, traffic
aids and sign gantries, water mains and fire hydrants, provision of facilities
for installation of traffic control and surveillance system (TCSS),
reprovisioning works of affected existing facilities, implementation of
transplanting, compensatory planting and protection of existing trees, and
implementation of an environmental monitoring and audit (EM&A) program.
Table 1.1 Contact
Information of Key Personnel
Party |
Position |
Name |
Telephone |
Fax |
Supervising Officer¡¦s Representative |
(Senior Resident
Engineer, SRE) |
Eddie Tsang |
3968 4802 |
2109 1882 |
Environmental Project Office / Independent Environmental Checker |
Environmental Project Office Leader |
Y. H. Hui |
3465 2888 |
3465 2899 |
Independent Environmental Checker |
Adi Lee |
9700 6767 |
3465 2899 |
|
Contractor |
Project Manager |
S. Y. Tse |
3968 7002 |
2109 2588 |
Environmental Officer |
Federick Wong |
3968 7117 |
2109 2588 |
|
Environmental Team (Meinhardt Infrastructure and Environment Limited) |
Environmental Team Leader |
Claudine Lee |
2859 5409 |
2559 0738 |
24 hours complaint
hotline |
--- |
--- |
5699 5730 |
--- |
|
Table 1.2 Construction Activities During Reporting Month
Description of Activities |
Site Area |
Landscape
maintenance works |
SHT East Portal |
Table 2.1 Action
and Limit Levels for 1-hour TSP
Monitoring Station |
Action Level, µg/m3 |
Limit Level, µg/m3 |
AMS 5 ¡V Ma Wan Chung Village (Tung Chung) |
352 |
500 |
AMS 6 ¡V Dragonair / CNAC (Group) Building
(HKIA) |
360 |
Table 2.2 Action
and Limit Levels for 24-hour TSP
Monitoring Station |
Action Level, µg/m3 |
Limit Level, µg/m3 |
AMS 5 ¡V Ma Wan Chung Village (Tung Chung) |
164 |
260 |
AMS 6 ¡V Dragonair / CNAC (Group) Building
(HKIA) |
173 |
260 |
Table 2.3 Air
Quality Monitoring Equipment
Equipment |
Brand and Model |
Portable direct reading dust meter (1-hour
TSP) |
Sibata Digital Dust Indicator (Model No. LD-5R) |
High Volume Sampler |
Tisch Environmental Mass Flow Controlled
Total Suspended Particulate (TSP) High Volume Air Sampler (Model No. TE-5170) |
Table 2.4 Locations
of Impact Air Quality Monitoring
Stations
Monitoring
Station |
Location |
AMS5 |
Ma Wan Chung Village (Tung Chung) |
AMS6 |
Dragonair / CNAC (Group) Building (HKIA) |
Table 2.5 Air
Quality Monitoring Parameters, Frequency and Duration
Parameter |
Frequency
and Duration |
1-hour TSP |
Three times every 6 days while the highest dust impact was expected |
24-hour TSP |
Once every 6 days |
(a) The HVS was installed in the vicinity of the air sensitive receivers.
The following criteria were considered in the installation of the HVS.
(i) A horizontal platform with appropriate support to secure the sampler
against gusty wind was provided.
(ii) The distance between the HVS and any obstacles, such as buildings, was
at least twice the height that the obstacle protrudes above the HVS.
(iii) A minimum of 2 meters separation from walls, parapets and penthouse for
rooftop sampler was provided.
(iv) No furnace or incinerator flues are nearby.
(v) Airflow around the sampler was unrestricted.
(vi) Permission was obtained to set up the samplers and access to the
monitoring stations.
(vii) A secured supply of electricity was obtained to operate the samplers.
(viii) The sampler was located more than 20 meters from any dripline.
(ix) Any wire fence and gate, required to protect the sampler, did not
obstruct the monitoring process.
(x) Flow control accuracy was kept within ¡Ó2.5% deviation over 24-hour
sampling period.
(b)
Preparation of Filter Papers
(i) Glass fibre filters, G810 were labelled and sufficient filters that were
clean and without pinholes were selected.
(ii)
All filters were equilibrated in the conditioning environment for 24
hours before weighing. The conditioning environment temperature was around
(iii)
All filter papers were prepared and analysed by ALS Technichem
(HK) Pty Ltd., which is a HOKLAS accredited laboratory and has comprehensive
quality assurance and quality control programmes.
(c) Field
Monitoring
(i) The power supply was checked to ensure the HVS works properly.
(ii) The filter holder and the area surrounding the filter were cleaned.
(iii) The filter holder was removed by loosening the four bolts and a new
filter, with stamped number upward, on a supporting screen was aligned
carefully.
(iv) The filter was properly aligned on the screen so that the gasket formed
an airtight seal on the outer edges of the filter.
(v)
The swing bolts were fastened to hold the filter holder down to the
frame. The pressure applied was
sufficient to avoid air leakage at the edges.
(vi) Then the shelter lid was closed and was secured with the aluminium
strip.
(vii) The HVS was warmed-up for about 5 minutes to establish run-temperature
conditions.
(viii) A new flow rate record sheet was set into the flow recorder.
(ix)
On site temperature and atmospheric pressure readings were taken and the
flow rate of the HVS was checked and adjusted at around 1.1 m3/min,
and complied with the range specified in the Updated EM&A Manual for HKLR
(Version 1.0) (i.e. 0.6-1.7 m3/min).
(x) The programmable digital timer was set for a sampling period of 24
hours, and the starting time, weather condition and the filter number were recorded.
(xi) The initial elapsed time was recorded.
(xii) At the end of sampling, on site temperature and atmospheric pressure
readings were taken and the final flow rate of the HVS was checked and
recorded.
(xiii)
The final elapsed time was recorded.
(xiv)
The sampled filter was removed carefully and folded in half length so that only surfaces with collected
particulate matter were in contact.
(xv)
It was then placed in a clean plastic envelope and sealed.
(xvi) All monitoring information was recorded on a standard data sheet.
(xvii) Filters were then sent to ALS Technichem (HK)
Pty Ltd. for analysis.
(d)
Maintenance and Calibration
(i) The HVS and its accessories were maintained in good working condition,
such as replacing motor brushes routinely and checking electrical wiring to
ensure a continuous power supply.
(ii) 5-point calibration of the HVS was conducted using TE
(iii) Calibration certificate of the HVSs are provided in Appendix C.
(a) Measuring Procedures
The measuring procedures of
the 1-hour dust meter were in accordance with the Manufacturer¡¦s Instruction
Manual as follows:-
(i)
Turn the power on.
(ii)
Close the air collecting opening cover.
(iii)
Push the ¡§TIME SETTING¡¨ switch to [BG].
(iv)
Push ¡§START/STOP¡¨ switch to perform background measurement for 6
seconds.
(v)
Turn the knob at SENSI ADJ position to insert the light scattering
plate.
(vi)
Leave the equipment for 1 minute upon ¡§SPAN CHECK¡¨ is indicated in the
display.
(vii)
Push ¡§START/STOP¡¨ switch to perform automatic sensitivity adjustment.
This measurement takes 1 minute.
(viii)
Pull out the knob and return it to MEASURE position.
(ix)
Push the ¡§TIME SETTING¡¨ switch the time set in the display to 3 hours.
(x)
Lower down the air collection opening cover.
(xi)
Push ¡§START/STOP¡¨ switch to start measurement.
(b) Maintenance
and Calibration
(i) The
1-hour TSP meter was calibrated at 1-year intervals against a Tisch
Environmental Mass Flow Controlled Total Suspended Particulate (TSP) High
Volume Air Sampler. Calibration certificates of the Laser Dust Monitors are
provided in Appendix C.
Table 2.6 Summary
of 1-hour TSP Monitoring Results During the Reporting Month
Monitoring Station |
Average (mg/m3) |
Range (mg/m3) |
Action Level (mg/m3) |
Limit Level (mg/m3) |
AMS5 |
22 |
19-33 |
352 |
500 |
AMS6 |
/ |
/ |
360 |
500 |
Table 2.7 Summary
of 24-hour TSP
Monitoring Results During the Reporting Month
Monitoring Station |
Average (mg/m3) |
Range (mg/m3) |
Action Level (mg/m3) |
Limit Level (mg/m3) |
AMS5 |
28 |
23-33 |
164 |
260 |
AMS6 |
/ |
/ |
173 |
260 |
Table 3.1 Action
and Limit Levels for Noise during Construction Period
Monitoring Station |
Time Period |
Action Level |
Limit Level |
NMS5 ¡V Ma Wan Chung
Village (Ma Wan Chung Resident Association) (Tung Chung) |
0700-1900 hours on normal
weekdays |
When one documented
complaint is received |
75 dB(A) |
Table 3.2 Noise
Monitoring Equipment
Equipment |
Brand and Model |
Integrated Sound Level
Meter |
B&K 2238 |
Acoustic Calibrator |
B&K 4231 |
Table 3.3 Locations
of Impact Noise Monitoring Stations
Monitoring Station |
Location |
NMS5 |
Ma Wan Chung Village (Ma Wan
Chung Resident Association) (Tung Chung) |
Table 3.4 Noise
Monitoring Parameters, Frequency and Duration
Parameter |
Frequency and Duration |
30-mins measurement at
each monitoring station between 0700 and 1900 on normal weekdays (Monday to
Saturday). Leq, L10 and L90
would be recorded. |
At least once per week |
(a) The sound level meter was
set on a tripod at a height of
(b)
The battery condition was
checked to ensure the correct functioning of the meter.
(c)
Parameters such as
frequency weighting, the time weighting and the measurement time were set as
follows:-
(i) frequency
weighting: A
(ii) time weighting: Fast
(iii) time
measurement: Leq(30-minutes)
during non-restricted hours i.e. 07:00 ¡V 1900 on normal weekdays
(d)
Prior to and after each
noise measurement, the meter was calibrated using the acoustic calibrator for
94.0 dB(A) at 1000 Hz. If the
difference in the calibration level before and after measurement was more than
1.0 dB(A), the measurement would be considered invalid and repeat of noise
measurement would be required after re-calibration or repair of the equipment.
(e)
During the monitoring
period, the Leq, L10 and L90
were recorded. In addition, site
conditions and noise sources were recorded on a standard record sheet.
(f)
Noise measurement was
paused during periods of high intrusive noise (e.g. dog barking, helicopter
noise) if possible. Observations were recorded when intrusive noise was
unavoidable.
(g)
Noise monitoring was
cancelled in the presence of fog, rain, wind with a steady speed exceeding
(a) The microphone head of the sound level
meter was cleaned with soft cloth at regular intervals.
(b) The meter and calibrator
were sent to the supplier or HOKLAS laboratory to check and calibrate at yearly
intervals.
(c) Calibration certificates
of the sound level meters and acoustic calibrators are provided in Appendix C.
Table 3.5 Summary
of Construction Noise Monitoring Results During the Reporting Month
Monitoring Station |
Average Leq
(30 mins), dB(A) |
Range of Leq
(30 mins), dB(A) |
Limit Level Leq
(30 mins), dB(A) |
NMS5 |
60 |
55-64 |
75 |
Table 4.1 Action
and Limit Levels for Water Quality
Parameter (unit) |
Water Depth |
Action Level |
Limit Level |
Dissolved Oxygen (mg/L)
(surface, middle and bottom) |
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.
Table 4.2 Water
Quality Monitoring Equipment
Equipment |
Brand and Model |
DO and Temperature Meter,
Salinity Meter, Turbidimeter and pH Meter |
N.A. (See Remark 1) |
Positioning Equipment |
N.A. (See Remark 1) |
Water Depth Detector |
N.A. (See Remark 1) |
Water Sampler |
N.A. (See Remark 1) |
Remark: 1. Not applicable. Water quality monitoring was temporarily suspended
during the reporting month. |
Table 4.3 Impact
Water Quality Monitoring Parameters and Frequency
Monitoring Stations |
Parameter, unit |
Frequency |
No. of depth |
Impact Stations: Control/Far Field
Stations: Sensitive Receiver
Stations: |
¡P
Depth, m ¡P
Temperature, oC ¡P
Salinity, ppt ¡P
Dissolved Oxygen
(DO), mg/L ¡P
DO Saturation, % ¡P
Turbidity, NTU ¡P
pH ¡P Suspended Solids (SS), mg/L |
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). |
Remark:
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) were 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) since 21 August 2019.
2) The water quality monitoring programme was temporarily suspended
during the reporting month since no marine works were scheduled or conducted,
therefore no water quality monitoring was conducted.
Table 4.4 Impact
Water Quality Monitoring Stations
Monitoring Stations |
Description |
Coordinates |
|
Easting |
Northing |
||
IS5 |
Impact Station (Close to
HKLR construction site) |
811579 |
817106 |
IS(Mf)6 |
Impact Station (Close to HKLR
construction site) |
812101 |
817873 |
IS7 |
Impact Station (Close to
HKBCF construction site) |
812244 |
818777 |
IS8(N) |
Impact Station (Close to
HKBCF construction site) |
814413 |
818570 |
IS(Mf)9 |
Impact Station (Close to HKBCF
construction site) |
813273 |
818850 |
IS10(N) |
Impact Station (Close to
HKBCF construction site) |
812942 |
820881 |
SR3(N) |
Sensitive receivers (San
Tau SSSI) |
810689 |
816591 |
SR4(N2) |
Sensitive receivers (Tai
Ho Inlet) |
814688 |
817996 |
SR5(N) |
Sensitive Receivers
(Artificial Reef in NE Airport) |
812569 |
821475 |
SR10A(N) |
Sensitive receivers (Ma
Wan Fish Culture Zone) |
823644 |
823484 |
SR10B(N2) |
Sensitive receivers (Ma
Wan Fish Culture Zone) |
823689 |
823159 |
CS2(A) |
Control Station (Mid-Ebb) |
805232 |
818606 |
CS(Mf)5 |
Control Station
(Mid-Flood) |
817990 |
821129 |
|
(a) The in-situ
water quality parameters including dissolved oxygen, temperature, salinity and
turbidity, pH were measured by multi-parameter meters.
(a) Digital Differential Global Positioning Systems
(DGPS) were used to ensure that the correct location was selected prior to
sample collection.
(b) Portable, battery-operated echo sounders were used
for the determination of water depth at each designated monitoring station.
(c) All in-situ measurements were taken at 3 water
depths, 1 m below water surface, mid-depth and 1 m above sea bed, except where
the water depth was less than 6 m, in which case the mid-depth station was
omitted. Should the water depth be less than 3 m, only the mid-depth station
was monitored.
(d) At each measurement/sampling depth, two consecutive
in-situ monitoring (DO concentration and saturation, temperature, turbidity,
pH, salinity) and water sample for SS. The probes were retrieved out of the
water after the first measurement and then re-deployed for the second
measurement. Where the difference in the value between the first and second
readings of DO or turbidity parameters was more than 25% of the value of the
first reading, the reading was discarded and further readings were taken.
(e) Duplicate samples from each independent sampling
event were collected for SS measurement. Water samples were collected using the
water samplers and the samples were stored in high-density polythene bottles.
Water samples collected were well-mixed in the water sampler prior to
pre-rinsing and transferring to sample bottles. Sample bottles were pre-rinsed
with the same water samples. The sample bottles were then be packed in
cool-boxes (cooled at 4oC without being frozen), and delivered to
ALS Technichem (HK) Pty Ltd. for the analysis of
suspended solids concentrations. The laboratory determination work would be
started within 24 hours after collection of the water samples. ALS Technichem (HK) Pty Ltd. is a HOKLAS accredited laboratory
and has comprehensive quality assurance and quality control programmes.
(f) The analysis method and detection limit for SS is
shown in Table 4.5.
Table 4.5 Laboratory
Analysis for Suspended Solids
Parameters |
Instrumentation |
Analytical
Method |
Detection
Limit |
Suspended Solid (SS) |
Weighting |
APHA 2540-D |
0.5mg/L |
(g) Other relevant data were recorded, including
monitoring location / position, time, water depth, tidal stages, weather
conditions and any special phenomena or work underway at the construction site
in the field log sheet for information.
Table 5.1 Action
and Limit Levels for Dolphin Monitoring
|
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 encounter
rate of number of dolphin sightings.
2.
ANI means quarterly
encounter rate of total number of dolphins.
3.
For North Lantau
Social Cluster, AL will be trigger if either NEL or NWL fall below the criteria; LL will be triggered if both NEL and NWL fall below the criteria.
Table 5.2 Co-ordinates
of Transect Lines
Line No. |
Easting |
Northing |
|
Line No. |
Easting |
Northing |
||
1 |
Start Point |
804671 |
815456 |
|
13 |
Start Point |
816506 |
819480 |
1 |
End Point |
804671 |
831404 |
|
13 |
End Point |
816506 |
824859 |
2 |
Start Point |
805476 |
820800* |
|
14 |
Start Point |
817537 |
820220 |
2 |
End Point |
805476 |
826654 |
|
14 |
End Point |
817537 |
824613 |
3 |
Start Point |
806464 |
821150* |
|
15 |
Start Point |
818568 |
820735 |
3 |
End Point |
806464 |
822911 |
|
15 |
End Point |
818568 |
824433 |
4 |
Start Point |
807518 |
821500* |
|
16 |
Start Point |
819532 |
821420 |
4 |
End Point |
807518 |
829230 |
|
16 |
End Point |
819532 |
824209 |
5 |
Start Point |
808504 |
821850* |
|
17 |
Start Point |
820451 |
822125 |
5 |
End Point |
808504 |
828602 |
|
17 |
End Point |
820451 |
823671 |
6 |
Start Point |
809490 |
822150* |
|
18 |
Start Point |
821504 |
822371 |
6 |
End Point |
809490 |
825352 |
|
18 |
End Point |
821504 |
823761 |
7 |
Start Point |
810499 |
822000* |
|
19 |
Start Point |
822513 |
823268 |
7 |
End Point |
810499 |
824613 |
|
19 |
End Point |
822513 |
824321 |
8 |
Start Point |
811508 |
821123 |
|
20 |
Start Point |
823477 |
823402 |
8 |
End Point |
811508 |
824254 |
|
20 |
End Point |
823477 |
824613 |
9 |
Start Point |
812516 |
821303 |
|
21 |
Start Point |
805476 |
827081 |
9 |
End Point |
812516 |
824254 |
|
21 |
End Point |
805476 |
830562 |
10 |
Start Point |
813525 |
821176 |
|
22 |
Start Point |
806464 |
824033 |
10 |
End Point |
813525 |
824657 |
|
22 |
End Point |
806464 |
829598 |
11 |
Start Point |
814556 |
818853 |
|
23 |
Start Point |
814559 |
821739 |
11 |
End Point |
814556 |
820992 |
|
23 |
End Point |
814559 |
824768 |
12 |
Start Point |
815542 |
818807 |
|
24* |
Start Point |
805476* |
815900* |
12 |
End Point |
815542 |
824882 |
|
24* |
End Point |
805476* |
819100* |
Note:
Co-ordinates in red and marked with asterisk are revised co-ordinates of
transect line.
Methodology
6.1.1
To avoid
disturbance to the mudflat and nuisance to navigation, no fixed
marker/monitoring rod was installed at the monitoring stations. A high
precision Global Navigation Satellite System (GNSS) real time location fixing
system (or equivalent technology) was used to locate the station in the
precision of 1mm, which is reasonable under flat mudflat topography with uneven
mudflat surface only at micro level.
This method has been used on Agricultural Fisheries and Conservation
Department¡¦s (AFCD) project, namely Baseline Ecological Monitoring Programme
for the Mai Po Inner Deep Bay Ramsar Site for measurement of seabed levels.
6.1.2
Measurements were
taken directly on the mudflat surface. The Real Time Kinematic GNSS (RTK GNSS)
surveying technology was used to measure mudflat surface levels and 3D
coordinates of a survey point. The
RTK GNSS survey was calibrated against a reference station in the field before
and after each survey. The
reference station is a survey control point established by the Lands Department
of the HKSAR Government or traditional land surveying methods using
professional surveying instruments such as total station, level and/or geodetic
GNSS. The coordinates system was in
HK1980 GRID system. For this
contract, the reference control station was surveyed and established by
traditional land surveying methods using professional surveying instruments
such as total station, level and RTK GNSS.
The accuracy was down to mm level so that the reference control station
has relatively higher accuracy. As
the reference control station has higher accuracy, it was set as true
evaluation relative to the RTK GNSS measurement. All position and height correction were
adjusted and corrected to the reference control station. Reference station survey result and
professional land surveying calibration is shown as Table 6.1:
Table 6.1 Reference
Station Survey result and GNSS RTK calibration result of Round 1
Reference Station |
Easting (m) |
Northing (m) |
Baseline reference elevation (mPD) (A) |
Round 1 Survey (mPD) (B) |
Calibration Adjustment (B-A) |
T1 |
811248.660mE |
816393.173mN |
3.840 |
3.817 |
-0.023 |
T2 |
810806.297mE |
815691.822mN |
4.625 |
4.653 |
+0.028 |
T3 |
810778.098mE |
815689.918mN |
4.651 |
4.660 |
+0.009 |
T4 |
810274.783mE |
816689.068mN |
2.637 |
2.709 |
+0.072 |
6.1.3
The precision
of the measured mudflat surface level reading (vertical precision setting) was
within 10 mm (standard deviation) after averaging the valid survey records of
the XYZ HK1980 GRID coordinates.
Each survey record at each station was computed by averaging at least
three measurements that are within the above specified precision setting. Both
digital data logging and written records were collected in the field. Field
data on station fixing and mudflat surface measurement were recorded.
Monitoring Locations
6.1.4
Four monitoring
stations were established based on the site conditions for the sedimentation
monitoring and are shown in Table
6.2.
Monitoring Results
6.1.5
The baseline
sedimentation rate monitoring was in September 2012 and impact sedimentation
rate monitoring was undertaken on 13 June 2022. The mudflat surface levels at
the four established monitoring stations and the corresponding XYZ HK1980 GRID
coordinates are presented in Table 6.2
and Table 6.3.
Table 6.2 Measured
Mudflat Surface Level Results
Baseline Monitoring
(September 2012) |
Impact Monitoring
(June 2022) |
|||||
Monitoring
Station |
Easting
(m) |
Northing
(m) |
Surface
Level (mPD) |
Easting
(m) |
Northing
(m) |
Surface
Level (mPD) |
S1 |
810291.160 |
816678.727 |
0.950 |
810291.157 |
816678.723 |
1.109 |
S2 |
810958.272 |
815831.531 |
0.864 |
810958.281 |
815831.525 |
0.960 |
S3 |
810716.585 |
815953.308 |
1.341 |
810716.593 |
815953.321 |
1.454 |
S4 |
811221.433 |
816151.381 |
0.931 |
811221.434 |
816151.385 |
1.119 |
Table 6.3 Comparison
of measurement
Comparison of measurement |
Remarks
and Recommendation |
|||
Monitoring Station |
Easting (m) |
Northing (m) |
Surface Level (mPD) |
|
S1 |
-0.003 |
-0.004 |
0.159 |
Level continuously increased |
S2 |
0.009 |
-0.006 |
0.096 |
Level continuously increased |
S3 |
0.008 |
0.013 |
0.113 |
Level continuously increased |
S4 |
-0.024 |
0.002 |
0.188 |
Level continuously increased |
6.1.6
This measurement result was generally and relatively
higher than the baseline measurement at S1, S2, S3 and S4. The mudflat level is
continuously increased.
6.2.1
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.
6.2.2
Water quality monitoring in San Tau (monitoring
station SR3(N)) was conducted in June 2022 as part of mudflat monitoring. The
monitoring parameters included dissolved oxygen (DO), turbidity and suspended
solids (SS). The water
monitoring results for station SR3(N) were extracted and summarised below:
Table 6.4 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) |
|
01-Jun-2022 |
8.0 |
3.8 |
0.7 |
8.0 |
4.5 |
0.8 |
03-Jun-2022 |
7.8 |
4.3 |
0.8 |
7.8 |
3.9 |
0.9 |
06-Jun-2022 |
7.5 |
4.6 |
3.4 |
7.6 |
4.4 |
2.9 |
08-Jun-2022 |
7.2 |
3.8 |
5.2 |
7.2 |
4.3 |
3.3 |
10-Jun-2022 |
7.5 |
5.4 |
1.2 |
7.5 |
4.8 |
2.4 |
13-Jun-2022 |
7.2 |
4.5 |
2.5 |
7.2 |
3.9 |
2.5 |
15-Jun-2022 |
7.5 |
3.4 |
1.5 |
7.5 |
4.2 |
1.5 |
17-Jun-2022 |
6.9 |
4.8 |
2.8 |
6.9 |
4.6 |
2.4 |
20-Jun-2022 |
7.2 |
3.8 |
2.8 |
7.2 |
3.9 |
2.4 |
22-Jun-2022 |
7.4 |
4.2 |
5.3 |
7.5 |
4.5 |
5.1 |
24-Jun-2022 |
7.8 |
4.8 |
2.7 |
7.8 |
5.2 |
2.4 |
27-Jun-2022 |
8.1 |
3.6 |
5.2 |
8.1 |
3.6 |
5.1 |
29-Jun-2022 |
8.4 |
3.8 |
2.6 |
8.3 |
3.6 |
3.2 |
Average |
7.6 |
4.2 |
2.8 |
7.6 |
4.3 |
2.7 |
|
Sampling Zone
6.3.1
To collect baseline information of
mudflats in the study site, the study site was divided into three sampling zones (labeled as TC1, TC2,
TC3) in Tung Chung Bay and one zone in San Tau (labeled as ST) (Figure 2.1 of Appendix I). The
horizontal shoreline of sampling zones TC1, TC2, TC3 and ST were about 250 m, 300 m, 300 m
and 250 m, respectively (Figure 2.2 of Appendix I). Survey
of horseshoe crabs, seagrass beds and intertidal communities were conducted in
every sampling zone. The present survey was conducted in June 2022 (totally 4 sampling days 13th (for ST), 14th (for TC1), 15th (for TC2) and 16th
(for TC3).
6.3.2
Since the field survey of June 2016,
increasing number of trashes and even big trashes (Figure 2.3 of Appendix I) 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
6.3.3
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 13th (for ST), 14th (for TC1), 15th (for TC2)
and 16th (for TC3) Jun 2022, which were fine days.
6.3.4
In June 2017, a big horseshoe crab was
tangled by a trash gill net in ST mudflat (Figure
2.3 of Appendix I). 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
6.3.5
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 13th (for ST), 14th (for TC1), 15th (for TC2)
and 16th (for TC3) Jun 2022, which were fine days.
Intertidal Soft Shore Communities
6.3.6
Field Sampling
6.3.7
The
intertidal soft shore community surveys were conducted in low tide period on 13th (for ST), 14th (for TC1), 15th (for TC2)
and 16th (for TC3) Jun 2022, . 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.
6.3.8 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 ( 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.
6.3.9 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.
6.3.10
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
6.3.11 Data collected from direct counting 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.
6.4.1
In the event of
the impact monitoring results indicating that the density or the distribution
pattern of intertidal fauna and seagrass is found to be significant different
to the baseline condition (taking into account natural fluctuation in the
occurrence and distribution pattern such as due to seasonal change),
appropriate actions should be taken and additional mitigation measures should
be implemented as necessary. Data
should then be re-assessed and the need for any further monitoring should be
established. The action plan, as given in Table
6.5 should be undertaken within a period of 1 month after a significant
difference has been determined.
Table 6.5 Event
and Action Plan for Mudflat Monitoring
Event |
ET Leader |
IEC |
SO |
Contractor |
Density or the distribution pattern of horseshoe
crab, seagrass or intertidal soft shore communities recorded in the
impact or post-construction monitoring are significantly lower than or
different from those recorded in the baseline monitoring. |
Review historical data to ensure differences are as a result of
natural variation or previously observed seasonal differences; Identify source(s) of impact; Inform the IEC, SO and Contractor; Check monitoring data; Discuss additional monitoring and any other measures, with the IEC and
Contractor. |
Discuss monitoring with the ET and the Contractor; Review proposals for additional monitoring and any other measures
submitted by the Contractor and advise the SO accordingly. |
Discuss with the IEC additional monitoring requirements and any other
measures proposed by the ET; Make agreement on the measures to be implemented. |
Inform the SO and in writing; Discuss with the ET and the IEC and propose measures to the IEC and
the ER; Implement the agreed measures. |
Notes:
ET ¡V Environmental Team
IEC ¡V Independent Environmental Checker
SO ¡V Supervising Officer
Horseshoe Crabs
6.5.1
In total of 13 individuals of Carcinoscorpius rotundicauda and
Tachypleus tridentatus
were found in present survey. The recorded individuals
were mainly distributed along the shoreline in TC1 and TC3. 7 adults specimens were recorded with one
mating pair, 4 being traped in an abandoned fish trap
and one died body. All of them were observed on similar
substratum (fine sand or soft mud, slightly submerged). 6 juveniles specimens were found in present
survey. Large adult individuals (prospmal width
>100mm) are excluded from the data analysis to avoid mixing up with juvenile
population living on intertidal habitat. Photo records of the
observed horseshoe crab are shown in Figure
3.1 of Appendix I and the present survey
result regarding horseshoe crab are presented in Table 3.1 of Appendix I. The complete survey
records are presented in Annex II of Appendix I.
6.5.2 For Carcinoscorpius rotundicauda, 1 individual was found in TC1with body size 54.42 mm. In TC3, 6 adults individuals with average body size 136.37mm (prosomal width ranged 131.4 ¡V 140.3mm) were found in present survey, with one mating pair and one died body.
The search record in ST (0.17 ind. hr-1. Person-1) and TC3 (1 ind. hr-1. Person-1) were very
low. No Carcinoscorpius rotundicauda was recorded in TC1 and TC2 in present survey.
6.5.3
For Tachypleus tridentatus,
5 individuals with average body size 54.03 mm (prosomal width ranged
43.27-62.38 mm) were found in ST in present survey. The search records in TC1
(0.83 ind. hr-1. Person-1) was very low. No Tachypleus
tridentatus was found in TC1, TC2 and TC3 in
present survey.
6.5.4
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 I). 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 Ishows 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 3.3 of Appendix I). One mating pair
was found in June 2022 (present survey).
6.5.5 7 large
individuals (prosomal width >100mm) of Carcinoscorpius
rotundicauda was recorded in June 2022 (present survey) (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 I. 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.
6.5.6 No marked
individual of horseshoe
crab was recorded in June 2022 (present survey). 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.
6.5.7 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
6.5.8
Figure 3.5 and 3.6 of Appendix I 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.
6.5.9
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 juvenil, 6 adults and 1 died
recorded.
6.5.10 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.
Seasonal variation of horseshoe crab population
6.5.14 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 I). 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.
6.5.15 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 I) 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(C 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.
6.5.16 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).
6.5.17 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.
6.5.18 Recently, Carcinoscorpius rotundicauda was a more common horseshoe crab species in
Tung Chung Wan. It was recorded in the four sampling zones while the majority
of population located in TC3 and ST. Due to potential breeding last year, 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
6.5.19 Figure 3.7 of Appendix Ishows 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.
6.5.20 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
6.5.21 Figure 3.8 of Appendix Ishows 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.
6.5.22 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.
6.5.23 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.
6.5.24 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).
Impact of the HKLR project
6.5.25 It was the 39th 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
6.5.26 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 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 ~19000m2 in moderate to high vegetation
coverage (50 ¡V 90%), ~8000m2 in moderate to high vegetation coverage
(40 ¡V 80%), ~2000m2 in moderate to high vegetation coverage (30 ¡V
70%) and three ~1000m2 in moderate vegetation coverage (22 ¡V 65%).
At close vicinity, one small sized (20m2) of Halophila ovalis beds
were observed at tidal zone 1.5m above C.D. All the small sized of Halophila
ovalis beds were in moderate vegetation coverage ranging from 30-60%. In
TC3, 3 large patches of Halophila ovalis were found at tidal zone 1.5m
above C.D. The larger strand had area ~1200m2 in moderate to high
vegetation coverage (40 ¡V 70%), ~1000m2 in moderate to high vegetation coverage
(30 ¡V 60%) and ~600m2 in moderate vegetation coverage (20-50%).
Another seagrass species Zostera japonica was found at tidal zone 2.0m
above C.D nearby mangroves plantation with ~20m2 in low to moderate
vegetation coverage (30 - 60%) in ST. Table 3.2 of Appendix I summarizes the
results of present seagrass beds survey and the photograph records of the
seagrass are shown on Figure 3.9 of Appendix I. The complete
record throughout the monitoring period is presented in Annex III of Appendix I.
6.5.27 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 I). 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.
6.5.28 According to the previous results, majority of seagrass bed was confined
in ST, the temporal change of both seagrass species were investigated in
details:
Temporal variation of seagrass beds in ST
6.5.29
Figure 3.11 of Appendix I 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 present survey was slightly decreased to
15m2.
6.5.30
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 TC1 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.
6.5.31
In December 2014, all the seagrass patches of
Halophila ovalis disappeared in ST. Figure 3.12 of Appendix I 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).
Unfavourable conditions to seagrass Halophila ovalis
6.5.32
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.
6.5.33
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).
6.5.34
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.
6.5.35
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
6.5.36
Figure 3.12 of Appendix I 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
6.5.37
In September 2017, the whole seagrass bed of Halophila
ovalis disappeared again along the shore of TC3 and ST (Figure 3.12 Appendix I). 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.
6.5.38
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.
6.5.39
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.
6.5.40
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 I). 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 680 m2, 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 I. 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 I.
Impact of the HKLR project
6.5.41
It was the 39th 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.
Intertidal Soft Shore
Communities
Substratum
6.5.42
Table 3.3 and Figure 3.13 of Appendix I show the substratum
types along the horizontal transect at every tidal level in all sampling zones.
The relative distribution of substratum types was estimated by categorizing the
substratum types (Gravels & Boulders / Sands / Soft mud) of the ten random
quadrats along the horizontal transect. The distribution of substratum types varied
among tidal levels and sampling zones:
¡P
In TC1, high percentages of ¡¥Gravels and
Boulders¡¦ (90%) were recorded at high tidal level. At mid tidal level, ¡¥Sands¡¦
was the main substratum type (70%), following by ¡¥Gravels and Boulders¡¦ (20%).
At low tidal level, ¡¥Soft mud¡¦ was the main substratum type (85%), followed by
¡¥Sands¡¦ (10%) and ¡¥Gravels and Boulders¡¦ (5%).
¡P
In TC2, high percentages of ¡¥Gravels and
Boulders¡¦ (70%) was recorded at high tidal level, following by ¡¥Sands¡¦ (20%).
At mid tidal level, ¡¥Sands¡¦ was the main substratum type (70%), following by¡¥Gravels and Boulders¡¦ (20%). At low tidal level, ¡¥Soft
mud¡¦ covered 85% and ¡¥Sands¡¦ covered 10% of the transect.
¡P
In TC3, higher percentage of ¡¥Gravels and
Boulders¡¦ was recorded at high tidal level (70%). At mid tidal levels, ¡¥Sands¡¦
was the main substratum type (80%), following by ¡¥Soft mud¡¦ (10%) and ¡¥Gravels
and Boulders¡¦ (10%). At low tidal level, ¡¥Soft mud¡¦ covered 80% of the
transect.
¡P
In ST, ¡¥Gravels and Boulders¡¦ was the main
substratum type (80%) at high tidal level. At mid tidal levels, ¡¥Soft mud¡¦ was
the main substratum type (65%), following by ¡¥Sand¡¦ (20%) and ¡¥Gravels and
Boulders¡¦ (15%). At low tidal level, ¡¥Soft mud¡¦ was the main substratum type
(80%) and ¡¥Sands¡¦ covered 20% of the transect.
6.5.43
There was neither consistent vertical nor
horizontal zonation pattern of substratum type in all sampling zones. Such
heterogeneous variation should be caused by different hydrology (e.g. wave in
different direction and intensity) received by the four sampling zones.
Soft shore
communities
6.5.44
Table 3.4 of Appendix I lists the total abundance, density and number
of taxon of every phylum in this survey. A total of 8511 individuals were
recorded. Mollusca was the most abundant phylum (total abundance 7600 ind.,
density 253 ind. m-2, relative abundance 89.3%). The second and
third were Arthropoda (634 ind., 21 ind. m-2, 7.4%) which followed
by Annelida (132 ind., 4 ind. m-2, 1.6%) and Sipuncula (81 ind., 3
ind. m-2, 1%), respectively. The fifth was Nemertea with total
abundance 36 ind., density 1 ind.m-2 and relative abundance 0.4%.
The sixth was Cnidania with total abundance 26 ind.,
density 1 ind.m-2 and relative abundance 0.3%.Platyhelminthes was
very low in abundances (density <0 ind. m-2, relative abundance £0.0%). 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.
6.5.45
The taxonomic resolution and complete list of
recorded fauna are shown in Annexes IV and V of Appendix I 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
Moreover, taxonomic
revision was conducted on another snail species while the specie name was
revised:
¡P
Batillaria bornii was revised as Clypeomorus bifasciata
6.5.46
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.
6.5.47
Table 3.5 of Appendix I shows the number of
individuals, relative abundance and density of each phylum in every sampling
zone. The total abundance (1,636 - 2,375 ind.) varied among the four sampling
zones while the phyla distributions were similar. In general, Mollusca was the
most dominant phylum (no. of individuals: 1,503 ¡V 2,181 ind.; relative
abundance 86.2 ¡V 91.9%; density 200 - 291 ind. m-2). Other phyla
were much lower in number of individuals. Arthropoda (87 - 263 ind.; 3.9 ¡V 12%;
12 - 35 ind. m-2) was common phyla relatively. Other phyla were very
low in abundance in all sampling zones.
Dominant species in every sampling zone
6.5.48
Table 3.6 of Appendix I 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.
6.5.50
In TC2, the substratum types were mainly '
Gravels and Boulders' at high tidal level.
The rock oyster Saccostrea cucullata
(84 ind. m-2, 28%) was dominant at low to moderate densities. The
gastropod Monodonta labio
(50 ind. m-2, 17%) and Batillaria
multiformis (41 ind. m-2, 14%) were of
low to moderate densities. At mid tidal level (main substratum types ¡¥Sands¡¦),
rock oyster Saccostrea cucullata (129 ind. m-2,
33%) was dominant at high density and gastropods Monodonta
labio (71 ind. m-2, 18%) and Batillaria zonalis
(54 ind. m-2, 14%) were dominant at moderate density. Substratum
types ¡¥Soft Mud¡¦ were mainly distributed at low tidal level, the Barbatia virescens
(46 ind. m-2, 19%) was dominant at low to moderate densities, the Batillaria multiformis
(31 ind. m-2, 13%), Lunella
granulate (26 ind. m-2, 11%) and Batillaria
zonalis (23 ind. m-2, 10%) were of low
density, regarded as common species.
6.5.53
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 (812
ind.), gastropods Monodonta labio (453 ind.) and Batillaria
multiformis (163 ind.) were the most common
species on gravel and boulders substratum. Batillaria
zonalis (220 ind.) was the most common species on
sands and soft mud substrata.
Biodiversity and abundance of soft shore communities
6.5.54
Table 3.7 of Appendix I 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.
6.5.55
Among the sampling zones, the mean species
number was varied from 14 - 20 spp. 0.25 m-2 among the four sampling
zones. The mean densities of TC3 (317 ind. m-2) was higher than ST
(307 ind. m-2) followed by TC2 (292 ind. m-2) and TC1
(218 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 and
TC3 were 2.1, TC1 was 1.9 and ST was 1.87, followed by while the mean J of TC1
and ST were 0.73, which were slightly lower than TC2 and TC3 (0.77). This can
be due to the relatively non-even taxa distribution.
6.5.56
In the present survey, no clear trend of mean
species number, mean density, H¡¦ and J observed among the tidal
level.
6.5.57
Figures 3.14 to 3.17 of Appendix I 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.
Impact of the HKLR
project
6.5.59
It was the 39th 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.
6.6.1
AFCD, 2018. Potamidid Snails in Hong Kong Mangrove. Agriculture,
Fisheries and Conservation Department Newsletter - Hong Kong Biodiversity Issue
#25, 2-11
6.6.2
Chan, K.K., Caley, K.J., 2003. Sandy Shores,
Hong Kong Field Guides 4. The Department of Ecology & Biodiversity, The
University of Hong Kong. pp 117.
6.6.3
Dai, A.Y., Yang, S.L., 1991. Crabs of the
China Seas. China Ocean Press. Beijing.
6.6.4
Dong, Y.M., 1991. Fauna of ZheJiang Crustacea. Zhejiang Science and Technology
Publishing House. ZheJiang.
6.6.5
EPD, 1997. Technical Memorandum on
Environmental Impact Assessment Process (1st edition). Environmental
Protection Department, HKSAR Government.
6.6.6
Fauchald, K., 1977. The polychaete worms. Definitions and keys to the orders,
families and genera. Natural History Museum of Los Angeles County, Science
Series 28. Los Angeles, U.S.A..
6.6.7
Fong, C.W., 1998. Distribution of Hong Kong
seagrasses. In: Porcupine! No. 18. The School of Biological Sciences, The
University of Hong Kong, in collaboration with Kadoorie
Farm & Botanic Garden Fauna Conservation Department, p10-12.
6.6.8
Li, H.Y., 2008. The Conservation of Horseshoe
Crabs in Hong Kong. MPhil Thesis, City University of Hong Kong, pp 277.
6.6.9
Longstaff, B.J., Dennison, W.C., 1999.
Seagrass survival during pulsed turbidity events: the effects of light
deprivation on the seagrasses Halodule pinifolia and Halophila
ovalis. Aquatic Botany 65 (1-4), 105-121.
6.6.10
Longstaff, B.J., Loneragan,
N.R., O¡¦Donohue, M.J., Dennison, W.C., 1999. Effects
of light deprivation on the survival and recovery of the seagrass Halophila ovalis (R. Br.) Hook. Journal
of Experimental Marine Biology and Ecology 234 (1), 1-27.
6.6.11
Nakaoka, M., Aioi, K., 1999. Growth of seagrass Halophila ovalis at dugong trails compared to existing within-patch
variation in a Thailand intertidal flat. Marine Ecology Progress Series 184,
97-103.
6.6.12
Pielou, E.C., 1966.
Shannon¡¦s formula as a measure of species diversity: its use and misuse.
American Naturalist 100, 463-465.
6.6.13
Qi, Z.Y., 2004. Seashells of China. China
Ocean Press. Beijing, China.
6.6.14
Qin, H., Chiu, H., Morton, B., 1998. Nursery
beaches for Horseshoe Crabs in Hong Kong. In: Porcupine! No. 18. The School of
Biological Sciences, The University of Hong Kong, in collaboration with Kadoorie Farm & Botanic Garden Fauna Conservation
Department, p9-10.
6.6.15
Shannon, C.E., Weaver, W., 1963. The
Mathematical Theory of Communication. Urbana: University of Illinois Press,
USA.
6.6.16
Shin, P.K.S., Li, H.Y., Cheung, S.G., 2009.
Horseshoe Crabs in Hong Kong: Current Population Status and Human Exploitation.
Biology and Conservation of Horseshoe Crabs (part 2), 347-360.
6.6.17
Supanwanid, C., 1996. Recovery
of the seagrass Halophila ovalis after
grazing by dugong. In: Kuo, J., Philips, R.C.,
Walker, D.I., Kirkman, H. (eds), Seagrass biology: Proc Int workshop, Rottenest
Island, Western Australia. Faculty of Science, The University of Western
Australia, Nedlands, 315-318.
6.6.18
Vermaat, J.E., Agawin, N.S.R., Duarte, C.M., Fortes, M.D., Marba. N., Uri, J.S., 1995. Meadow maintenance, growth and
productivity of a mixed Philippine seagrass bed. Marine Ecology Progress Series
124, 215-225.
6.6.19 Yang, D.J, Sun, R.P.,
1988. Polychaetous annelids commonly seen from the
Chinese waters (Chinese version). China Agriculture Press, China.
Table 7.1 Summary
of Environmental Site Inspections
Date of Audit |
Observations |
Actions Taken by
Contractor / Recommendation |
Date of Observations Closed |
18, 27 Mar 2020; 1, 8, 15, 22, 28 Apr 2020; 6, 13, 20, 29 May 2020; 3,
10, 17, 26 Jun 2020; 2, 8, 15, 22, 31 Jul 2020; 5, 12, 21, 28 Aug 2020; 2, 9,
16, 23, 29 Sep 2020; 7, 14, 21, 30 Oct 2020; 4, 11, 18, 27 Nov 2020; 2, 9,
16, 23, 29 Dec 2020; 6, 13, 20, 29 Jan 2021; 3, 10, 17, 26 Feb; 3, 11, 17, 26
Mar; 1, 7, 15, 21, 29 Apr 2021, 6, 12, 20, 28 May 2021; 2, 9, 16, 25 Jun
2021; 2, 7, 14, 21, 30 Jul 2021; 4, 11, 18, 27 Aug 2021; 1, 8, 15, 24, 30 Sep
2021; 6, 12, 20, 29 Oct 2021; 3, 10, 17, 24, 30 Nov 2021; 8, 16, 22, 31 Dec
2021; 5, 12, 19, 28, 31 Jan 2022; 9, 16, 25 Feb; 2, 9, 16, 25, 31 Mar; 6, 14,
21, 29 Apr 2022; 4, 11, 17, 25, 31 May 2022 |
1.
Gaps
of silt curtains were observed at Portion X. |
1.
The
silt curtains maintenance work is in progress at Portion X. The Contractor was reminded to maintain the silt curtains at Portion X. |
Follow-up actions for the observations will
be inspected during site inspection in Jan 2022. |
8 June 2022 |
1. Gaps of silt curtains were observed/ part of silt curtains
were missing at Portion X. |
1.
The Contractor was reminded to
maintain the silt curtains at Portion X. |
Follow-up actions for the observations
issued for the last weekly site inspection of the reporting month will be
inspected during the next site inspection. |
14 June 2022 |
1. Gaps of silt curtains were observed/ part of silt curtains
were missing at Portion X. |
1.
The Contractor was reminded to
maintain the silt curtains at Portion X. |
Follow-up actions for the observations
issued for the last weekly site inspection of the reporting month will be
inspected during the next site inspection. |
22 June 2022 |
1. Gaps of silt curtains were observed/ part of silt curtains
were missing at Portion X. |
1.
The Contractor was reminded to
maintain the silt curtains at Portion X. |
Follow-up actions for the observations
issued for the last weekly site inspection of the reporting month will be
inspected during the next site inspection. |
28 June 2022 |
1. Gaps of silt curtains were observed/ part of silt curtains
were missing at Portion X. |
1.
The Contractor was reminded to
maintain the silt curtains at Portion X. |
Follow-up actions for the observations will
be inspected during site inspection in July 2022. |
Table 7.2 A
Summary of Environmental Complaint during the Reporting Month
Environmental Complaint No. |
Date of Complaint Received |
Description of Environmental Complaint |
COM-2022-166 |
IEC/ENPO notified Contractor, ET and SOR regarding the complaint on 28
June 2022. |
Waste Management |
Table 8.1 Construction
Activities for July 2022
Site Area |
Description of Activities |
SHT East Portal |
Landscape maintenance
works |