Despite legislation requiring that the preservation of saltmarshes be considered prior to developments that could harm their ecological integrity, saltmarshes continue to be destroyed and altered. Part of the rationale for encouraging the conservation of saltmarshes has been their assumed importance as fish habitat, especially for juveniles of economically important species (Hyland & Butler 1989). This role needs demonstrating, with a view to strengthening demands that saltmarsh habitat be retained in the face of increasing urbanisation.

Apart from direct loss of saltmarshes through urban development in southeast Qld and northern NSW, several other human activities are destroying or degrading saltmarshes. Anthropogenic changes to saltmarshes can result in loss of vegetation through changes in drainage regimes and salinity levels (Ruiz et al. 1993). While maps have been produced showing loss of saltmarshes in subtropical Australia (Hyland & Butler 1989), loss of vegetation from extant marshes has not been catalogued, despite the massive changes in drainage regimes, modification of marshes to control mosquitoes, grazing by stock, and use of marshes by off-road vehicles.

Debate about the role of vegetation in structuring fish communities of intertidal and subtidal habitats other than saltmarshes has been based on numerous comparisons of vegetated and unvegetated habitats (eg. in seagrass meadows, Connolly (1994b,c) and mangroves). In these habitats vegetated areas tend to have higher abundances and greater species richness. No attempt has been made in Australia to consider the role of vegetation in determining fish abundances on saltmarshes.

This proposal takes the first step towards determining the importance of saltmarsh habitat to fisheries by examining whether fish directly use inundated saltmarsh flats and whether vegetation plays a role in determining how many fish go there.