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Space-time variability in phytoplankton communities in the South Australian shelf waters

Abstract

The South Australian shelf waters, while a priori thought to be oligotrophic, support large fisheries and aquaculture activities. In this region, the space-time dynamics of phytoplankton communities is still poorly understood and nothing is known about nutrients pathways. Variation of the structure of the water column with seasonal upwelling events occurring in the region may provide important source of nutrients to sustain the high productivity of the system. In this context, we investigated how the structure and function of the phytoplankton community may be controlled by changes in nutrients levels and the structure of the water column. Distinct patterns were observed in the structure and function of the phytoplankton communities. Such changes in phytoplankton communities were related to the cool and nutrient rich upwelled waters in summer and local differences in the physico-chemical properties of the water column during winter. Variations in the phytoplankton community together with changes in the structure of the water column are used to quantify the role of physical processes in understanding the mechanisms responsible for the sustainability of the phytoplankton resource in South Australian waters.