The South-west Corner Marine Park survey used standardised methods to characterise seabed habitats and fish populations to support the ongoing monitoring of the marine park. Several small isolated high-profile reefs exist in depths of ~30-50 m in the south-east of the National Park Zone, with the majority of mid-shelf habitat consisting of flat pavement reefs interspersed with sand sediments. Both reef types supported diverse assemblages of macroalgae, seagrass, soft corals and sponges. Further offshore, ledge features at ~100 m depth support diverse filter feeders dominated by hard bryozoans, hydroids, black and octocorals and sponges. Dense filter feeding assemblages on the edge of the shelf break down to 250 m depth were populated by aggregations of hapuka (Polyprion oxygeneios). A potential aggregation site for grey nurse sharks (Carcharias taurus) within the National Park Zone was also found. Additional image annotation and analysis aims to provide further details on assemblages.

This report is part of a series of eco-narrative documents that synthesize our existing knowledge of Australia’s individual Marine Parks. This series is a product of the National Environmental Science Program Marine Biodiversity Hub Project D3, which seeks to determine the status of marine biodiversity assets on the continental shelf to inform monitoring of Australian Marine Parks. The South-west Corner Marine Park contains large areas of high biodiversity and benthic productivity, although most of the Marine Park still remains to be surveyed. The Park is defined by extensive plains across the continental shelf covered by mixed communities of macroalgae, seagrasses and sponges. Since these plains cover ~95% of the surveyed area, such communities account for a large proportion of benthic productivity and biodiversity in the region. Black and octocorals, hydroids and bryozoans are present in deeper areas of the continental shelf, while areas deeper than 120 m are mostly formed by soft sediments. A total of 140 fish species across 61 families were identified in the Marine Park, including several shark species and other commercially targeted species. The Park is also habitat for numerous seabirds and migratory passage for several cetacean species.