We examined variations in organic carbon (OC) pools and microplanktonic carbon fluxes at three stations in the Hudson River estuary during 12 cruises between Octobers of 1996 and 1998. Phytoplankton biomass and net primary production varied from 5 to 40 µmol C L −1 and 0.3 to 318.3 mmol C m −2 d −1 , respectively. Biomass and production of bacterioplankton in the surface layer commonly exceeded those of phytoplankton, varying...