2               Dolphin Acoustic Behaviour Monitoring

Monitoring Requirements

2.1  According to EM&A Manual Section 10.3.4, acoustic behavior and movement of Chinese White Dolphin near the bored piling sites should be monitored during bridge construction.

Monitoring Location

2.2         The dedicated acoustic surveys with calibrated hydrophone deployment were conducted in the western side of Lantau Island during the construction phase. The research vessel followed a predefined route for systematic search effort in West Lantau waters to cover the HKLR alignment in Northwest and West Lantau waters (in particular the area near the first three bored piling sites), where dolphins will be potentially disturbed by the bored piling works.

2.3         The EARs were deployed at two locations: 1) near the bridge alignment (N22°17.222, E113°53.016), about 500 m from the first three bored piling sites (P48, P50 & P52 - Site B2), and 2) at a less disturbed site away from the bridge alignment as control site, off Fan Lau (N22°11.827, 113°50.648; Site B1).  EAR B2 was in water depth 4 m, and EAR B1 in 7 m. The location of Site B1 and B2 are shown in Figure 2.

Monitoring Frequency

2.4         Thirty days of monitoring during bored piling activities were carried out during the construction phase.

Monitoring Day

2.5         In March 2013, a total of 23 days of acoustic monitoring surveys were conducted between March 6th and 30th 2013. A total of 8 days and 2 days of acoustic monitoring surveys were conducted during the bored piling activities for P48 and P52 respectively.

 

2.6         In April 2013, a total of 8 days of acoustic monitoring surveys were conducted on the 1st, 2nd, 3rd, 5th, 7th, 8th, 10th and 11th April 2013, when bored piling activities were concurrently conducted at Piers 48 and 52.

 

2.7         In July 2013, a total of 12 days of acoustic monitoring surveys were conducted on the 9th, 11th, 12th, 15th, 16th, 17th, 18th, 22nd, 23rd, 24th, 25th and 26th, when bored piling activities were concurrently conducted.

 

2.8         The dolphin acoustic behaviour monitoring schedule is shown in Appendix B. 


 

Monitoring Results

 

2.9         A total of 30 days of acoustic monitoring surveys were conducted in March, April and July 2013, when bored piling activities were concurrently conducted. During those dates, 2,751.8 km of survey effort were conducted to search for dolphins in the western and northwestern waters of Lantau.  A total of 91 groups, numbering 301 dolphins, were sighted during these surveys.  In addition, 67 sound samples of recordings were taken from the surveys.  Moreover, the EARs were deployed at Fan Lau (site B1) and near the bridge alignment (Site B2).

 

2.10     Detailed monitoring methodology and results can be found in Appendix C.

 

2.11     According to the Dolphin Acoustic Behaviour Monitoring Impact Phase Monitoring Report prepared by Dolphin Specialist as shown in Appendix C, summary of the dolphin acoustic behavior monitoring results is shown in Table 2.1.

Table 2.1.  Values of the two response variables of dolphin acoustic behaviour collected by calibrated hydrophone (average clicks and whistles per minutes) by size of group, behavioural state and time of day during baseline and impact monitoring periods. (The numerical values highlighted in blue indicated that the values recorded in impact monitoring period have triggered the Action Level (20% higher or lower than the baseline period), while the ones highlighted in red indicated a triggering of Limit Level (40% higher or lower than the baseline period). Only the cells highlighted in yellow have found significant differences between the values recorded in impact and baseline monitoring periods, while no significant difference was found in other comparisons even though some have triggered the Action or Limit Level.)

 

Average clicks per minute ( ± s.d.)

Average whistles per minute ( ± s.d.)

Group Size

1 dolphins

Baseline

62.19 ± 77.73 (n=21)

0.21 ± 1.49 (n=19)

Impact

119.11 ± 201.67 (n=11)

0.13 ± 0.30 (n=11)

2-5 dolphins

Baseline

54.03 ± 179.32 (n=82)

0.56 ± 1.70 (n=126)

Impact

54.17 ± 95.45 (n=46)

0.09 ± 0.20 (n=46)

6-9 dolphins

Baseline

118.00 ± 310.31 (n=23)

1.58 ± 4.63 (n=38)

Impact

106.06 ± 199.58 (n=26)

0.97 ± 1.99 (n=26)

10+ dolphins

Baseline

289.33 ± 140.58 (n=20)

2.74 ± 1.99 (n=36)

Impact

n/a

n/a

Behavioural State

Feeding

Baseline

30.95 ± 69.90 (n=16)

0.62 ± 1.33 (n=29)

Impact

19.30 ± 29.62 (n=11)

0.16 ± 0.26 (n=11)

Milling

Baseline

71.29 ± 205.44 (n=90)

0.66 ± 1.85 (n=139)

Impact

80.09 ± 136.86 (n=54)

0.18 ± 0.60 (n=54)

Socializing

Baseline

287.48 ± 326.22 (n=20)

3.78 ± 4.14 (n=26)

Impact

213.12 ± 309.71 (n=7)

2.48 ± 3.16 (n=7)

Traveling

Baseline

13.16 ± 208.94 (n=11)

0.25 ± 1.48 (n=12)

Impact

52.34 ± 32.53 (n=7)

0.17 ± 0.29 (n=7)

Resting

Baseline

0.10 ± 70.35 (n=2)

0.13 ± 1.43 (n=6)

Impact

n/a

n/a

Time of day

09:00-10:59

Baseline

38.14 ± 69.90 (n=15)

0.70 ± 1.33 (n=29)

Impact

74.39 ± 124.79 (n=31)

0.32 ± 0.75 (n=31)

11:00-12:59

Baseline

79.97 ± 144.51 (n=68)

0.68 ± 1.86 (n=94)

Impact

110.73 ± 218.62 (n=26)

0.66 ± 1.78 (n=26)

13:00-14:59

Baseline

159.41 ± 303.43 (n=44)

1.74 ± 3.80 (n=62)

Impact

43.35 ± 72.50 (n=17)

0.03 ± 0.08 (n=17)

15:00-16:59

Baseline

65.40 ± 140.58 (n=17)

1.16 ± 1.99 (n=36)

Impact

49.90 ± 69.04 (n=12)

0.42 ± 1.20 (n=12)

 

Event and Action Plan

 

2.12     The detailed Event and Action Plan is presented in Table 2.3.

 

Table 2.3    Event and Action Plan on Dolphin Acoustic Behaviour

EVENT

ACTION

ET Leader

IEC

SO

Contractor

Action Level

With the numerical values presented in Table 1, when any of the response variable for dolphin acoustic behaviour recorded in the construction phase monitoring is 20% lower or higher than that recorded in the baseline monitoring, or when there is a shift of 3 hours or more in peak occurrence at B2 Site (i.e. 00:00 – 01:00), the action level should be triggered

 

1. Repeat statistical data analysis to confirm findings;

2. Review all available and relevant data to ascertain if differences are as a result of natural variation or seasonal differences;

3. Identify source(s) of impact;

4. Inform the IEC, SO and Contractor;

5. Check monitoring data;

6. Carry out audit to ensure all dolphin protective measures are implemented fully and additional measures be proposed if necessary

 

1. Check monitoring data submitted by ET and Contractor;

2. Discuss monitoring with the ET and the Contractor;

 

 

1. Discuss with the IEC the repeat monitoring and any other measures proposed by the ET;

2. Make agreement on measures to be implemented.

 

1. Inform the SO and confirm notification of the non- compliance in writing;

2. Discuss with the ET and the IEC and propose measures to the IEC and the SO;

3. Implement the agreed measures.

Limit Level

With the numerical values presented in Table 1, when any of the response variable for dolphin acoustic behaviour recorded in the construction phase monitoring is 40% lower or higher than that recorded in the baseline monitoring, or when there is a shift of 6 hours or more in peak occurrence at B2 Site (i.e. 00:00 – 01:00), the limit level should be triggered

 

1. Repeat statistical data analysis to confirm findings;

2. Review all available and relevant data to ascertain if differences are as a result of natural variation or seasonal differences;

3. Identify source(s) of impact;

4. Inform the IEC, SO and Contractor;

5. Check monitoring data;

6. Carry out audit to ensure all dolphin protective measures are implemented fully and additional measures be proposed if necessary

7. Discuss additional dolphin monitoring and any other potential mitigation measures (e.g. consider to temporarily stop relevant portion of construction activity) with the IEC and Contractor.

 

1. Check monitoring data submitted by ET and Contractor;

2. Discuss monitoring with the ET and the Contractor;

3. Review proposals for additional monitoring and any other measures submitted by the Contractor and advise ER accordingly.

 

1. Discuss with the IEC the repeat monitoring and any other measures proposed by the ET;

2. Make agreement on measures to be implemented.

 

1. Inform the SO and confirm notification of the non- compliance in writing;

2. Discuss with the ET and the IEC and propose measures to the IEC and the SO;

3. Implement the agreed measures.

Abbreviations: ET – Environmental Team, IEC – Independent Environmental Checker, SO – Supervising Officer

 

2.13     Detailed monitoring methodology and results can be found in Appendix C.

 

2.14     According to Table 2.1, there were four Action Level (AL) exceedances and four Limit Level (LL) exceedances in the clicking rates, while there were three AL exceedances and seven LL exceedances in the whistling rates. However, only significant differences were found in both the whistling and clicking rates recorded in the afternoon time period between 13:00 and 14:59.

 

2.15     As the Environmental Team of the Contract, all the monitoring data and statistical data analysis as presented in Appendix C have been checked and reviewed according to Table 2.3.

 

2.16     No direct evidence that the exceedances were due to the bored piling activities under the Contract according to the Dolphin Acoustic Behaviour Monitoring Impact Phase Monitoring Report in Appendix C:

Ø  The majority of the exceedances are not statistically significant due to small sample size;

Ø  Different type of vessels recorded during baseline and construction may contribute the significant different values of response variables between baseline and construction phases;

Ø  Natural seasonal variation including the addition of strong seasonal fish chorusing, and that other than anthropogenic influences may cause the different dolphins’ acoustic behaviour between baseline and construction phase dolphin monitoring;

Ø  The change in peak occurrence does not only occur at the site of impact (Site B2) but also at the control site (Site B1);

Ø  The decrease in number of sightings was also mainly occurred in Zone 1 and Zone 3 which were away from the construction site of the Contract according to Figure 9a and 9b in Appendix C;

Ø  Significant increases in the ambient noise levels measured at both sites B1 and B2 during the construction phase which may affect the dolphins’ acoustic behaviour.

 

 

 

 

 

Implementation Status of Environmental Mitigation Measures

2.17     In order to minimize impact on dolphins’ acoustic behaviour, dolphin protection measures as described below were properly implemented during the marine works for the Contract:

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

 

Ø  Acoustic decoupling measures for the stationary equipment (generators, winch generators and air compressors) mounted on boards were adopted according to the approved Acoustic Decoupling Measures Plan, EP Condition 3.7 and EM&A Manual, Section 10.2.18.

 

Ø  Dolphin exclusion zone and dolphin watching plan according to EM&A Manual, Section 10.2.12 and 10.2.17 respectively.