Seabed habitat on the south-eastern Australian continental shelf: context, vulnerability and monitoring

Abstract

A hierarchical approach to mapping seabed habitat is presented. A provincial scale survey that included hydrography and geology provided the context for interpreting habitat use and vulnerability. A megascale map, developed in cooperation with local fishers, identified major seabed features (kilometres to 10s of kilometres). Vulnerability of a feature was defined as its resistance to physical modification and its resilience, or capacity to recover, on removal of the modifier. Vulnerability was assessed from geological, biological and oceanological properties. Inner-shelf sandstone and limestone reefs that were exposed and weathered during the last ice age, and shelf-break bryozoan patch reefs, appear to be the most vulnerable of the hard-grounds to physical disturbance. In contrast, larger, high-relief, outer-shelf fossiliferous limestone reefs appear relatively invulnerable to physical disturbance from fishing. Megascale features were the focus of detailed physical and biological sampling at the mesoscale level (10 m to km), the level of resolution necessary for establishing baseline conditions and monitoring change. The hierarchical approach used here to map seabed habitat amalgamates scientific and fishers’ information. Approached in this way, habitat mapping has the potential to build a common framework of knowledge on which effective spatial management can be based.