Phytoplankton diversity and ecology in estuaries of southeastern NSW, Australia

Phytoplankton, as one of the most important primary producers in aquatic ecosystems, have been widely used to indicate the health of such ecosystems, but they are a poorly understood component of coastal plant communities in Australia. The primary objective of this study was to address a number of gaps in the current knowledge of phytoplankton in the estuaries of southeastern Australia. An extensive literature review on phytoplankton diversity and ecology in the estuaries of Australia was conducted to identify knowledge gaps. There are more than 130 estuaries in New South Wales, Australia (NSW), but almost no single set of comprehensive information on phytoplankton taxonomy has been established, and very few studies on the seasonal and annual patterns of phytoplankton distribution have been carried out. The thresholds or standards to assess the changes of aquatic environments using phytoplankton are therefore difficult to establish, even though an increasing number of bloom events indicates an urgent need to monitor the dynamics of phytoplankton assemblages. Thus, seven representative estuaries, which cover about 400 km of the southeastern NSW coast, were chosen for study of the general characteristics of phytoplankton diversity and ecology. A more detailed comparative study of the phytoplankton assemblages in two lakes with different nutrient status and a historical study of environmental change using diatom frustules in sediments of one lake as indicators were also completed. In addition, the growth of key species was studied to explore the governing environmental factors. In the seven estuaries, 145 phytoplankton species were identified, covering five groups Cyanophyta, Chlorophyta, Chromophyta, Diatom and Pyrrophyta. Diatom and Pyrrophyta species were the main contributors to the phytoplankton diversity. Phytoplankton assemblages were characterized by a large number of temperate water species combined with a smaller number of warm water species, reflecting the warm temperate climate in the studied areas. The proportions of brackish and freshwater to