Research on Antarctic Coastal Ecosystem Rates: (RACER) Mechanisms of Bloom Formation and Decline

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Historical data and observations from studies of the coastal Antarctic Peninsula region provide detailed documentation of massive phytoplankton blooms which develop within the Gerlache Strait and the southwest portion of the Bransfield Strait. Hydrographic data indicate that the flow field is relatively quiescent in the region of bloom formation. The objectives of the proposed work are to understand the temporal detail regarding the mechanisms leading to formation and decline of these blooms. This component of the RACER (Research on Antarctic Coastal Ecosystem Rates) program will utilize an interdisciplinary approach to resolve the phytoplankton response to physical forcing. The emphasis will be on high temporal resolution of meteorological forcing of turbulent mixing within the upper water column, and the response of the phytoplankton. This will be accomplished with a permanent meteorological station on an island adjacent to the primary station and rapid profiling of physical- optical-biological properties. Detailed studies of phytoplankton rate processes including carbon and nitrogen isotope uptake studies, growth rates determined by radio-carbon labelling of chlorophyll a, and kinetics of photoadaptation will be carried out. The photoadaptive status of the phytoplankton crop will be determined from optical, biochemical, and photosynthetic parameters. This information is essential for an understanding of the underlying mechanisms of bloom formation. Such an understanding is required for development of mechanistic models which are capable of predicting seasonal progression and interannual variability forced by the physical environment.