Enhanced ROV Survey of Tropical Fish and Benthic Communities Associated With Shallow Oil and Gas Platforms

Understanding the ecology of oil and gas infrastructure in our oceans is required to inform decommissioning such that environmental impacts are minimised, and benefits maximised. This study equipped an industrial remotely operated vehicle (ROV) with a stereo-video system and collected seven hours of high-definition imagery of two platform jackets, for assessments of benthic (type, density, complexity) and fish assemblages (richness, abundance, length) present. Harriet Alpha (25 m depth) and Gibson/South Plato (8 m depth) are located ca. 120 km offshore of north-west Australia, adjacent to Varanus Island. Twenty-one ‘classes’ of benthic biota were observed in high density, with little bare structure on either platform. Encrusting sponges (average 19% cover per virtual quadrat), barnacles (17%) and sponges (16%) were common on Gibson/South Plato while encrusting sponges (16%) and macroalgae (18%) were ubiquitous on quadrats on Harriet Alpha. The sun coral Tubastraea faulkneri was common on Harriet Alpha (38% of quadrats), though coverage was low (