Rick D Stuart-Smith, Daniela Ceccarelli, Graham J Edgar, Antonia T Cooper. Report to Parks Australia, Department of the Environment, 2017.

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Reef Life Survey Assessment of Rocky Reef Biodiversity in the South-West Marine Region (Geographe CMR)

Executive summary

The South-west Commonwealth Marine Reserve (CMR) Network includes Commonwealth waters from the eastern end of Kangaroo Island, South Australia, to 70 km offshore of Shark Bay, Western Australia, and covers an area of 1.3 million km2.

The Geographe CMR is one of 14 CMRs established in the South-west CMR Network, and is the only one to contain shallow rocky reef in depths surveyable by SCUBA divers.

It covers 977 km2 , and a depth range of approximately 15 to 70 m within Georgraphe Bay.

Three types of IUCN zoning exist within the Geographe CMR: Marine National Park Zone (IUCN Category II), Special Purpose Zone (IUCN VI) and Multiple Use Zone (IUCN Category VI).

Reef Life Survey (RLS) dive teams surveyed 14 transects at seven sites on reefs in the vicinity of the Geographe CMR, including two transects at one site within the IUCN II area and six reference sites at nearby inshore locations.

Reef Life Survey (RLS) involves recreational divers trained to a scientific level of data-gathering to make it possible to conduct ecological surveys across broad geographic areas in a cost-effective manner.

The Geographe CMR had a richer benthic assemblage than the reference sites and greater fish species richness and biomass, but this assessment is based on only two transects within the CMR, and reference sites were located inshore in shallower and different habitat.

Thus, further surveys are required within the CMR and outside its boundaries, but along the same reef system, before the distinctiveness of the CMR fauna can be better characterised, and more reliable conclusions drawn from the inside-outside differences.

The fish assemblage in the inshore reference sites appeared to transition along a geographical gradient, possibly in response to changing levels of exposure to the southwesterly swell.