Integrating seafloor habitat mapping and fish assemblage patterns improves spatial management planning in a marine park

Marine Protected Areas (MPAs) are important spatial mechanisms for managing human activities, if effectively planned. The Solitary Islands Marine Park (SIMP), covering 720 km² of coastal waters in New South Wales, Australia, includes reef and unconsolidated habitats up to 17 km from shore and 75 m depth. When established in 1991, there was limited knowledge of biotic patterns, seafloor habitats and habitat-biotic relationships in the multiple-use SIMP, which constrained effective conservation planning. Subsequent mapping of sub-tidal habitats from aerial photography and single-beam acoustics improved habitat representation following rezoning in 2002 using Comprehensive, Adequate, Representative (CAR) principles and assisted site selection for diver surveys of fishes, a key surrogate taxon. In 2006, a swath acoustic mapping program commenced, which mapped ~35% of the MPA. This has produced high-resolution data on seafloor habitats, including depths >50 m. Bathymetry and backscatter layers have facilitated targeted deployment of Baited Remote Underwater Video (BRUV) to test hypotheses about associations between fishes and physical habitat characteristics. Strong and persistent patterns in fish assemblage composition in relation to particular habitat characteristics provided the basis for a Habitat Classification Scheme (HCS) to be refined with the following categories: substratum (consolidated, unconsolidated), cross-shelf position (inshore, mid, offshore) and depth (shallow, intermediate, deep). Further refinement of unconsolidated substratum into gravel and sand habitats, which were mapped using backscatter layers, improves this classification. The HCS, which integrates habitat and biotic patterns, greatly increases the potential for effective spatial management planning in the SIMP when used with spatial planning tools (e.g. Marxan).