Spatial Variation of Picoplankton Community Structure in the Northern Gulf of Mexico

Abstract

Marine microbes are responsible for over half of global primary productivity; Prochlorococcus and Synechococcus are the most abundant of these microbes, accounting for over a trillion trillion of the single-celled organisms in the world’s oceans These picoplankton, each exploiting a unique pigment scheme, are easily sorted and counted (cells/mL-1) based on fluorescence signatures and light scattering patterns using dual beam flow cytometry. Prochlorococcus, Synechococcus, and picoeukaryotes were sampled in summer 2012 in the Gulf of Mexico, an economically significant yet understudied sea. Vertical profiles were constructed to describe the spatial variation of picoplankton in response to nutrients (nitrate and phosphate), temperature and salinity throughout the northern Gulf of Mexico. The response of these picoplankton communities to varying environmental conditions suggests an alteration of community structure in response to anthropogenic factors such as elevated nutrient inputs into the Gulf and alteration of habitat due to drilling. As exploitation of the Gulf’s resources increases, continuing to understand the response of picoplankton will be crucial in sustaining the productivity of these waters.