River flows and estuarine ecosystems: Implications for coastal fisheries from a review and a case study of the Logan River, southeast Queensland

River discharge has long been recognized as one of the factors that contrib utes to the high productivity of estuaries. Although there is little eviden ce that river inputs of terrestrial carbon make a direct contribution to co astal food webs, such exported nutrients may stimulate in situ production i n estuaries and thus enhance the survivorship and growth of fish and crusta ceans in these systems. Furthermore, fluctuations in salinity and turbidity may influence the extent of available habitat for fish and crustaceans and therefore their distribution and/or catchability. Despite these potential links between flow and the secondary production of estuaries and coastal wa ters, there is still a common perception that 'water going to sea is wasted ' and a continuing trend to regulate the flow of rivers. We review the evid ence for links between river flow and the productivity of estuarine/coastal fisheries, drawing on a case study of the Logan River in southeast Queensl and, and explore the potential mechanisms for these linkages. Our research, and that of others, confirms that high river discharge can have a strong p ositive effect on the production of commercial and recreational coastal fis heries. It also shows that the seasonal pattern of flow is equally, if not more important, than the magnitude of flow River regulation is likely to ha ve a dramatic effect on the production of coastal fisheries and, given the current pressures for water resource development, this is an important aven ue for future research and evaluation.