9.1 The marine ecological assessment for this Project concluded that as the majority of construction works associated with the project are terrestrial based only minor impacts on marine ecological resources are expected. However small scale marine works would take place at Aberdeen PTW that would have a direct impact on coral colonies and intertidal communities within the works area. The intertidal communities identified in the directly impacted area have a very low ecological value and as the removed artificial seawall habitat would be re-constructed only minor and acceptable impact is expected. To avoid direct loss or damage to any species of conservation interest, it is recommended that coral colonies identified in the works area are translocated to a nearby suitable habitat. The recipient site identified is at the eastern end of the existing seawall where other colonies of the same species were identified at similar depths.
9.2 Mitigation measures defined in the water quality Section 6 of the EIA report would control indirect construction phase impacts on marine ecological resources to within acceptable levels. These impacts will be monitored through impacts to water quality (see Section 4 of this EM&A Manual).
9.3 Mitigation measures and EM&A requirements for the protection of marine ecological resources during the operational phase of the project are detailed in the water quality Section 4 and Ecological Risk Assessment Section 6 of this Manual.
9.4
Coral
colonies that would be directly impacted during construction works at Aberdeen
PTW have been identified as Oulastrea crispata during the baseline survey for the EIA report. Oulastrea crispata has a wide range of adaptations to different
environmental conditions (including those unfavourable to corals) as well as
geographic locations, which is a result of its stress-tolerant ability (Chen, et al. 2003). With an opportunistic life
history trait, a wide range of reproductive strategies and surface-orientation
independent growth, O. crispata is
able to colonise a variety of substrata and to flourish as a pioneer coloniser
of newly immersed structures (Lam,
9.5
Only 3 colonies of O. crispata, all small in size and of
low coverage would be affected (Figure 9.1). They were attached to small
boulders and translocation of the affected coral colonies was feasible. To mitigate the direct impact
imposed on these coral colonies it is proposed that they are translocated to
the eastern end of the existing seawall, which has similar hydrographic
parameters and supports healthy growth of the same species and is thus
considered as a suitable recipient site (Figure 9.1).
9.6
Coral translocation should be
carried out during the winter season (November-March) in order to avoid
disturbance to the transplanted colonies during the spawning period (i.e. July
to October).
9.7 General methodology for the coral translocation process is proposed below.
Ÿ Locate a suitable recipient site for transplanted corals before commencement of coral translocation works. Proposed recipient site should contain healthy coral communities of same species and have a similar hydrographic condition;
Ÿ Collect baseline information (e.g. total number of coral colonies to be translocated, size, health status, attached boulder size, etc.) of coral colonies in pre-translocation survey before commencement of coral translocation works;
Ÿ Tag the corals colonies to be transplanted one by one in the pre-translocation survey;
Ÿ Record the size, depth and orientation of each tagged coral colonies in the pre-translocation survey;
Ÿ Move boulders with translocated coral colonies from sea bottom to ship/boat with lifting bag;
Ÿ Submerge translocated coral colonies in large plastic bucket filled with seawater and provide adequate aeration onboard the transportation vessel;
Ÿ Transport coral colonies to recipient site as quickly as possible;
Ÿ Place the transplanted coral colonies in the recipient site in similar depth and orientation as the original coral site;
Ÿ Record information (e.g. health status, translocated location of tagged coral, etc) of transplanted coral colonies upon the completion of translocation works; and
Ÿ Carry out post-translocation monitoring on transplanted coral colonies every three months for a year after completion of coral translocation works.
9.8 No construction phase monitoring of translocated corals is deemed necessary as water quality modelling predicted that there would be no adverse water quality impact at the identified recipient site during the construction phase of the project.
9.9 Although adverse impact on coral colonies within the Project area is not predicted to occur after implementation of the suggested mitigation measures, post-translocation coral monitoring was proposed in the EIA report as an additional measure to verify if translocation was successful.
9.10 A detailed translocation plan (including identification of recipient site, pre-translocation survey, translocation methodology, monitoring of transplanted corals, etc.) should be drafted, approved by the Director and carried out prior to any construction works. All coral survey, translocation and monitoring exercises should be carried out by a qualified marine specialist who has suitable coral knowledge and sound experience in identifying corals in field situation, to be approved by the Director.
9.11 Prior to the commencement of coral translocation, to update information, a baseline survey of the three coral colonies that would be directly affected during construction should be conducted. The GPS coordinates of each colony were recorded during the baseline survey for the EIA Report (Refer to Appendix E, of this manual). Each coral colony should be tagged and for each colony, specific detailed information should be collected including location, size, depth, attached rock/boulder size and the general condition of the immediate surroundings. The condition of each tagged coral colony should also be recorded by taking a photograph from an angle that best represents the entire colony.
9.12 The health status of each tagged coral colony should be carefully recorded. For hard corals, this should include information on existing surface area with partial mortality and bleached area. Two categories of bleached area should be recorded:
Ÿ Blanched (i.e. paled)
Ÿ Bleached (i.e. bleached white)
9.13 Blanched coral tissue would appear pale due a partial loss of zooxanthallae or photosynthetic pigments. In contrast, bleached areas would appear white due to the white colouration of the skeleton visible through the transparent coral tissue. Bleaching results from total loss of zooxanthellae but coral tissue would still be present. It is possible that the lower portions of the coral tissue remain unbleached and thus the colony is said to be blanched. Where coral tissue is absent and only the skeleton remains the colony is dead.
9.14
For each tagged hard coral
colony, sediment cover should be recorded including percentage cover,
colouration, texture and approximate thickness of sediment on the colony itself
and on adjacent hard substrate. Any contiguous patches of sediment cover
>10% should be counted. To aid percentage cover estimates, a
9.15
After translocation, the
transplanted coral colonies should be regularly checked by qualified marine
ecologist(s), to be approved by the Director, every 3 months for a year. Dive
surveys for post-translocation monitoring should collect the same information
for tagged corals as the baseline survey. Information gathered during each
post-translocation monitoring survey should include observations on the
presence, survival, health condition and growth of the transplanted coral
colonies. Oulastrea crispata is not
expected to grow significantly over the one year monitoring period but previous
study (Lam, 2000) has shown it to have a growth rate of 0.9
9.16 Post-translocation monitoring should also include condition of the surrounding environment as well as weather, visibility, sea and tidal conditions. Each tagged coral should be photographed as far as possible maintaining the same aspect and orientation as photographs taken for the baseline survey. Detailed monitoring proposal should be drafted and approved by the Director prior to the commencement of construction works and coral translocation.
9.17
All tags should be removed /
retrieved after the monitoring programme is completed.
9.18 A baseline survey report should be submitted to the Director prior to the commencement of coral translocation exercise for reporting the results of the translocation exercise.
9.19 Post-translocation monitoring report should be submitted to the Director within 2 weeks after the completion of coral translocation and each subsequent monitoring survey. The results of the post-translocation monitoring surveys should be reviewed with reference to the baseline survey results and findings of the condition of surrounding environment.