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

A hierarchical approach to mapping seabed habitat is presented. A provincia l scale survey that included hydrography and geology provided the context f or interpreting habitat use and vulnerability. A megascale map, developed i n cooperation with local fishers, identified major seabed features (kilomet res to 10s of kilometres). Vulnerability of a feature was defined as its re sistance to physical modification and its resilience, or capacity to recove r, on removal of the modifier. Vulnerability was assessed from geological, biological and oceanological properties. Inner-shelf sandstone and limeston e 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-gr ounds to physical disturbance. In contrast, larger, high-relief, outer-shel f fossiliferous limestone reefs appear relatively invulnerable to physical disturbance from fishing. Megascale features were the focus of detailed phy sical and biological sampling at the mesoscale level (10 m to km), the leve l of resolution necessary for establishing baseline conditions and monitori ng change. The hierarchical approach used here to map seabed habitat amalga mates 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.