Lee, R.S., Pritchard, T.R., Ajani, P.A. and Black, K.P., 2007. The influence of the East Australian Current eddy field on phytoplankton dynamics in the coastal zone. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 576 – 584. Gold Coast, Australia, ISSN 0749.0208

Phytoplankton blooms are often studied too late in their development when the surface expression of predominantly senescent cells triggers an investigation. As a result studies typically depict an environment exhausted of nutrients and provide limited information on the mechanisms that caused the bloom. The purpose of the study reported here is to quantify the oceanographic and meteorological conditions leading to nutrient enrichment and subsequent phytoplankton responses (blooms) through a series of cross-shelf flux studies undertaken over spring/summer seasons in the 1990's along Australia's east-coast. The region is impacted by western boundary current encroachments of the East Australian Current (EAC), and anthropogenic inputs from the Newcastle-Sydney-Wollongong conurbation. Synoptically triggered responsive sampling transects along a 300km section of the shelf, identified coherent diatom - dinoflagellate successions over several weeks after oceanic nutrient enrichment of shelf waters. Concurrent physical observations identified perturbations of the East Australian Current into meanders, eddies and back-eddies by coastal and shelf topography as a key influence in determining the local nutrient budget and phytoplankton distributions. Response of the heterotrophic dinoflagellate Noctiluca scintillans (Macartney) occurred after sufficient critical prey mass of diatoms was achieved and overwhelmed zooplankton communities. The extent and duration of these blooms were unprecedented in these coastal waters, and were mitigated by local prevailing circulation patterns. Suggestions that preferential diatom feeding by Noctiluca may control its abundance, and that climatic variance may determine the dominant diatom population, indicate these events fluctuate inter-annually rather than seasonally.