WAMSI 2 - Dredging Node - Project 7.5 - Effects of Dredging Related Pressures on Critical Ecological Processes for Coral - SETTLEMENT STUDIES, Western Australia

Data will be in the form of a report, which will be a secured (printable, non-editable), searchable, Portable Document Format (PDF) showing the results of the experiments. Settlement studies (Project 7.5): It is believed that coral larvae prefer to settle on sediment-free surfaces and this key recruitment process may be affected by suspended solids and deposition from dredging. The objective of project 7.5 is to examine if the settlement of broadcast spawning and brooding corals are affected by sediments from dredging and the primary cause:effect pathway whereby sediments can affect settlement. Larval settlement and metamorphosis will be examined in small (200 L) or larger (up to 1000 L) mesocosm tanks where light, turbidity and sedimentation rate can be controlled and measured and where corals will be exposed to a realistic range of TSS concentrations and PSDs on settlement success over an incubation period of several days. The experiment will require developing settling media which present the larvae with differently orientated locations/planes in which to settle. Light levels will also be manipulated to mimic the shading expected during dredging events and the combinations of orientation, sedimentation, TSS and light levels will help identify cause-effect relationships that affect settlement success. The settlement studies will be conducted with planulae with either broadcast spawning or brooding species and these projects may be combined depending on availability of test material (planulae) for experimentation. Experiments will be conducted each year (over a 3 year period) during the coral spawning period (October-December) for broadcast spawning species and during the year with brooding species.