Dr Conrad Speed1, Ms Samantha Jaworski1, Dr Luke Thomas1, Dr Dianne McLean1
1Australian Institute of Marine Science, Perth, Crawley, Australia
Biography:
Dr Conrad Speed is a Research Scientist at the Australian Institute of Marine Science and has been working as a tropical reef ecologist, specialising in the movement and behaviour of sharks and predatory fish for the past fifteen years. Conrad has authored numerous papers in international scientific journals, focusing on predatory fish communities and the drivers of their movement.
Abstract:
As many offshore oil and gas structures reach the end of their productive lives, likely impacts of infrastructure removal on local marine life associated with these structures have become important decommissioning considerations for operators and regulators. To date, remotely operated vehicle (ROV) videos have generally been used for inspection and maintenance but can also provide snap shots of marine life along pipelines and around platforms. Here, we provide the results of a comprehensive survey of marine life around an offshore platform and pipeline in northwestern Australia to help inform decommissioning. We utilised three methods to assess fish communities and diets, including ROV surveys, fish trapping, and environmental DNA (eDNA) metabarcoding. We then compared fish community structure using metrics of abundance and richness from ROV surveys and eDNA metabarcoding of seawater samples and analysed the fish community diet by applying eDNA metabarcoding techniques to a subsample of the hindgut contents. Here we describe fish communities and their diet composition around offshore infrastructure in contrast to natural reference sites, contributing to an understanding of the value of infrastructure as habitat for fish species. Our results provide a more holistic assessment of the fish community and diet than any single approach used in isolation and are being used to directly inform decommissioning decisions that minimise impacts to marine life.