Title: Phytoplankton and nutrient dynamics in New South Wales coastal waters
Supervisors: Dr. Martina A. Doblin (UTS) and Dr. Christel Hassler (CSIRO)
Australia’s coasts are uniquely influenced by two southward flowing currents: the Leeuwin Current on the west coast, and the East Australia Current (EAC) on its east. The EAC is of great interest because it has a profound impact on the oceanography of the entire eastern seaboard. As it moves eastward from the continental shelf, it separates the cooler waters of the Tasman Sea and the warm oligotrophic waters of the Coral Sea, forming the Tasman Front. The EAC is involved in the formation of cold-core and warm-core eddies, and it is these various interactions with water masses that influence the marine flora and fauna of the region.
Phytoplankton populations in general are governed by three main factors: light, nutrients and temperature. Concentrations of essential nutrients will often determine the rate of growth for phytoplankton. Coupled with the amount of light that penetrates the euphotic zone and water temperature, these features will then determine the composition and diversity of phytoplankton in differing water masses.
Phytoplankton community structure, and productivity are therefore highly influenced by physical and chemical factors, both of which are subject to changes in climate
a) To examine the phytoplankton standing stock, productivity and species composition associated with different oceanographic features in NSW shelf waters. These features include the EAC; inside and outside an oceanic cold core eddy; inside a coastal eddy and in NSW coastal waters.
b) To identify correlations of phytoplankton with ambient nutrient concentrations in defined oceanographic features.
c) To determine whether phytoplankton within defined oceanographic features respond to nutrient addition.
Analyses will be undertaken to assess phytoplankton in each oceanographic feature: physiological health, abundance, biomass and productivity of phytoplankton will be determined from samples taken from the RV Southern Surveyor during a cruise in 2008 (SS10/08).
Laboratory analysis of phytoplankton pigments (in conjunction with CSIRO) will be undertaken to determine phytoplankton species composition. To assess foodweb structure, and changes in phytoplankton biomass during ship board perturbation experiments to assess nutrient limitation, standard isotope analysis will be undertaken.