Rick Stuart-Smith, Dani Ceccarelli, Paul Day, Graham Edgar, Antonia Cooper, Liz Oh, Camille Mellin. Report to Parks Australia, Department of the Environment, 2020.

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• Reef Life Survey Assessment of Marine Biodiversity in Geographe Bay

Executive summary

The Geographe Marine Park is one of 14 Australian Marine Parks established in the South-west Marine Parks Network (SWMPN), which emcompasses an area of 508,371 km2 within the South-west Marine Region that extends from eastern Kangaroo Island, South Australia, to 70 km offshore of Shark Bay, Western Australia (WA). Four zoning categories exist within the Geographe Marine Park: Habitat Protection (IUCN IV), Multiple Use (IUCN VI), Special Purpose (Mining Exclusion, IUCN VI) and National Park (IUCN II) zones (Parks Australia 2019).

There has been very little research in the Geographe Marine Park to help understand differences in biodiversity values protected in each of these zones and provide adequate baselines for future evaluation of management effectiveness. This report presents the findings of Reef Life Survey (RLS) surveys conducted in 2017 and 2019, which targeted reef habitats in two zoning categories before and just following implementation of the Geographe Marine Park.

Fish, macroinvertebrate and benthic communities in Geographe Marine Park changed little between 2017 and 2019, both in the Habitat Protection (IUCN IV) and Multiple Use (IUCN VI) zones. Minor changes observed reflected largely idiosyncratic trends associated with the small number of surveys (only four sites were surveyed; two in each zone).

The similarity in reef communities between years in both zones was expected because the park management plan was formally implemented less than a year prior to the 2019 surveys (i.e. there was insufficient time for any ‘management effect’), and because no sites were within the National Park Zone in the final zoning scheme (IUCN II, with greater fishing restrictions). Stability in fish biomass and Community Temperature Index values suggested no substantial human or environmentally driven changes occurred between the 2017 and 2019 surveys either.

The high similarity between sites suggests that sites within the Multiple Use Zone are well matched to the Habitat Protection Zone sites in terms of habitat and reef communities, and should therefore act as good reference sites. Similarly, the lack of major differences between years suggests that the overall period investigated should provide a good baseline against which future change can be assessed.