Global shifts in phytoplankton community size structure in response to environmental controls

Global phytoplankton communities have been changing in response to a shifting climate. This is most easily highlighted in research at long-term ocean time series sites such as BATS and CARIACO that have documented shifts in species composition towards the dominance of smaller-celled phytoplankton linked directly to trends in the physical drivers of nutrient availability in these systems. Such changes have far reaching implications for the magnitude and efficiency of the biological carbon pump and for the structure and function of higher trophic levels. We aim to explore changing patterns in phytoplankton community diversity, specifically as it relates to cell size distribution, on a global scale in response to environmental controls. Using satellite data products and the absorption based approach of Mouw and Yoder (2010), we retrieve the proportional contributions of micro- and pico-plankton to the total phytoplankton community across both SeaWiFS and MODIS missions from 1997 to 2015. We characterize spatial and temporal variability in community size structure on seasonal, inter-annual and long-term time scales in relation to physical drivers of the system, such as temperature and light.