Multi-decadal analysis of phytoplankton biomass in the northeast U.S. continental shelf large marine ecosystem

The Northeast U.S. Continental Shelf Large Marine Ecosystem (NES LME), encompassing the area between Cape Hatteras and the Gulf of Maine, has experienced a general warming trend since the 1960’s.  This highly productive ecosystem has four distinct eco-regions (from south to north: Middle-Atlantic Bight, Southern New England Shelf, Georges Bank and Gulf of Maine) that have different spatial and temporal patterns of phytoplankton biomass and production.  Preliminary comparisons of in situ annual surface chlorophyll concentrations from the MARMAP study (1977-1988) and ocean color remote sensing data (CZCS 1978-1986, SeaWiFS 1997-2008 and MODIS-Aqua 2002-2008) indicate that surface phytoplankton biomass in the present decade (geometric mean = 1.48 mg m^-3) is 33% higher than during the MARMAP period (geometric mean = 0.99 mg m^-3).  The current study evaluates the agreement between the CZCS satellite derived and in situ measured chlorophyll and creates a blended chlorophyll product.  Comparisons of seasonal phytoplankton biomass patterns during the two study periods show changes in the total biomass and phenology in the four major eco-regions.  This investigation of the temporal and spatial patterns of phytoplankton biomass and productivity should help better characterize the linkages between primary producers and the upper trophic levels in this LME.