Pleistocene-Holocene Southern Ocean coccolithophore calcification and productivity

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Marine phytoplankton form the basis of pelagic food webs and ecosystems. With modern anthropogenic environmental impacts - including eutrophication, climate change and ocean acidification - there is evidence that this group is already experiencing biogeographic range shifts and changes to community structure. Here, we seek to investigate the response of a key group of marine phytoplankton to rapid environmental change, especially acidification, in the Southern Ocean. The alage concerned produce calcium carbonate (calcite) plate-like scales, which are produced by and surround the cell during life, but on death accumulate in great numbers in deep ocean sediments. These fossil scales, called coccoliths, can be used to reconstruct the abundance and diversity of species that were living in the surface ocean across millions of years. The chemistry of coccoliths can also be used as an indicator of cell processes and the conditions in the surface ocean environment at the time the coccoliths were formed. Together, we propose to use the variations in the size and abundances of coccoliths produced by different species, as well as chemical indicators of cell growth rates and environment, to determine the response of coccolithophore algae in the Southern Ocean to intervals of rapid ocean acidification in the recent past, specifically those associated with rapid increases in atmospheric carbon dioxide concentrations at the end of glacial climate intervals.