Estuarine Structure, Function and Health
Non Technical Summary
The high density of population along the NSW coast puts ever-increasing demands on coastal resources. Over the past ten years the focus of a number of state and local government agencies has adapted to meet this challenge, and it is the view of the authors that the classification of estuaries and the determination of their degree of maturity can enhance this process. Management focus is enhanced by the fact that estuaries can be categorised in three major geomorphologic types: drowned river valley, barrier estuary and intermittently open estuary. Furthermore, as all estuaries fill with marine and fluvial sediment, the amount of infilling establishes their degree of maturity. The classification and evolutionary status of NSW estuaries will be illustrated in a presentation to the 11th Coastal Management Conference.
Our presentation is designed to summarise the conclusions of a paper by P.S. Roy and others published in the international journal "Estuarine, Coastal and Shelf Science" in September 2001. The original paper is based on the collective experience of ten authors employed in state, local and academic institutions who have extensively dealt with coastal science and management over the past two decades. Their study sets out a framework for research and management based on the premise that the geological structure of estuaries controls the functions that occur in them. The presentation to be given at the 11th Coastal Management Conference summarises the original article and adds thoughts on the topic of "estuarine health". One of the features that helps determine estuarine "health" is the presence and balance of estuarine plants including phytoplankton, seagrass, mangrove and saltmarsh. The utility of assessments of the historical distributions of seagrass, mangrove and saltmarsh with aerial photographs is illustrated.
As a consequence of the interactions between structure, function and health, the management implications for local governments vary widely. For example, Bega Valley Shire must cater for the differing zones and evolutionary status of ten barrier and thirteen intermittent estuaries, whereas Kogarah Municipal Council borders a relatively small part of the central mud basin of the Georges River. As councils carry a great responsibility for estuarine management, it is appropriate to disseminate the notions of estuarine structure, function and health as widely as possible.