Australia has a diverse array of estuaries influenced by coastal wave action, the movement of tides and river flow. The position of estuaries along a coast is ultimately dictated by topography and sea level (Kench 1999), whereas the relative strength of the key physical energy sources dictates the form of the estuary. Because climate will influence the key physical energy sources, different types of estuaries may be differentially affected. Estuarine form then influences water flow, nutrient cyclingandecosystemprocesseswithintheestuary(Turneretal. 2004). Six to seven main types of estuary are found in Australia, depending on whether drowned river valleys and embayments are included (Table 1). In general, wave-dominated estuaries predominate in southern Australia and tide-dominated systems are common in northern Australia, where they grade into deltas with increasing sediment input (Heap et al. 2004).