Developing a habitat classification typology for subtidal habitats in a temperate estuary in New South Wales, Australia

Effective estuarine management depends on adequate data about the ecology, extent and biodiversity of component habitats. However, these data are often scant, as exemplified by the Port Stephens estuary, part of the Port Stephens–Great Lakes Marine Park (NSW, Australia), for which even basic descriptions of habitat types and extent are lacking. Herein we present the results of the first quantitative assessment of subtidal benthic communities within the estuary, involving 130 km of towed video transects over an area exceeding 50 km². We identified previously undocumented macroalgae-dominated habitat types and found strong correlations between habitat types and depth. The soft coral Dendronephthya australis habitat is of particular interest because this was found to occur exclusively outside current sanctuary (no take) zones. The habitat map of Port Stephens generated during the study provides the basis for more objective representative planning in future iterations of zoning in the estuarine section of the marine park. The study also suggests that depth may be a useful proxy for estuarine habitat types where specific data are lacking. The classification methodology developed during the study was cost-effective, generated robust data and consequently has potential for wider application in other large estuarine bays.