Studies of Phytoplankton Species and Photosynthetic Pigments in a Warm Core Eddy of the East Australian Current. I. Summer Populations

Summer phytoplankton populations in a warm core eddy of the East Australian Current were studied by thin-layer chromatography for pigments and by microscopy of living samples for species identification. Small differences in phytoplankton populations at the eddy centre compared to surrounding waters were observed. These included higher subsurface chlorophyll maxima (0.49-0.89 pg 1-' eddy centre; 0.33-0.38 pg 1-' eddy edge; 0.27-0.34 yg I-' midway positions) due to increased diatom abundance, a lower proportion of nanoplankton chlorophyll (52 % eddy centre; 73 % eddy edge), a dominance change from Rhizosolenia alata (eddy edge) to Nitzschia seriata (eddy centre), and a decreased number of dinoflagellate species.