Interactions between Cobalt, Cadmium, and Zinc Biogeochemistry and Phytoplankton Dynamics in the Ross Sea

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The proposed work extends the scope of an interdisciplinary shipboard program to investigate the environmental factors that regulate the distribution and production of antarctic algal groups in the Ross Sea, by adding cobalt, cadmium, and zinc trace metal analyses to the iron component that had been included in a previously funded project. The additional trace metal analyses will be highly complementary to the cruise objectives because carbon acquisition by marine phytoplankton is known to be dependent on carbonic anhydrase, a metalloenzyme that may be activated by any of these three trace elements.Studies of phytoplankton abundances in the Ross Sea region have shown that productivity is dominated by two major phytoplankton groups: Phaeocystis antarctica and diatoms. Diatoms tend to dominate in highly stratified waters, while Phaeocystis is dominant where deeper mixing is observed, implying that Phaeocystis are more efficient under low light conditions. Phaeocystis populations have been observed to cause rapid and early export of carbon from the photic zone, leading to the hypothesis that CO2 drawdown could decrease significantly if climate-induced upper ocean stratification were to increase. ***