Grant: Discovery Grants Program - Individual

One of the main questions challenging environmental scientists is to understand how increasing anthropogenic carbon dioxide concentrations will change climate. The ocean is one of the most important reservoirs of inorganic carbon, and its ability to act as a long-term sink for CO2 is affected by phytoplankton through the flux of photosynthetically fixed carbon from the surface into the deep ocean, termed the biological pump. The magnitude and efficiency of the biological pump are among the most important and least understood components in climate research. The biological pump is affected by changes in the phytoplankton community structure, specifically size and taxonomic structure that change with evolutionary processes and respond to environmental conditions. This research program proposes to investigate the effect of climate change on phytoplankton community structure through the following projects: I) an evaluation of the macroevolutionary changes in the size structure of marine dinoflagellates (organic cysts) and diatoms (silica frustules) in response to climate change over the Cenozoic and part of the Mesozoic, II) testing for latitudinal gradients in the size structure of diatoms and dinoflagellate assemblages, and determining if these gradients have changed over geological time, III) determining how catastrophic biotic crises, such as occurred at the end-Cretaceous, affected the size structure of the phytoplankton and carbon cycling, IV) investigation of the role of nutrient concentration on the size structure of phytoplankton communities using a combination of laboratory experiments and ecophysiological models, V) assessment of the potential role of silicon availability in altering the morphostructure of diatom frustules and the associated implications for carbon cycling. The goal of this research program is to elucidate how environmental change has altered phytoplankton communities and the biological pump over geological time to improve our ability to predict how current and future climate change may interact with phytoplankton community structure.