Large-scale climate forcing linked to phytoplankton biomass variability in the Northwest Atlantic

No abstracts are to be cited without prior reference to the author.

Phytoplankton are the base of the marine food web and a recent study of Large Marine Ecosystems (LMEs) worldwide suggested that high fisheries yield is associated with high surface chlorophyll-a (chl-a), a proxy for phytoplankton biomass. Here we analyzed satellite-derived chl-a from two different sensors (SeaWiFS & MODIS) at two different time-periods (1997-2010 & 2002-2012) covering the region of the United States Northeast Shelf Large Marine Ecosystem (U.S. NES LME) and off-shelf waters. We conducted an empirical orthogonal function (EOF) analysis of 1-km chl-a data that was post-processed using a regional algorithm to improve chl-a estimates in case-2 waters close to coastlines. We identified areas within the U.S. NES LME that had the strongest interannual variability of chl-a and analyzed relationships to large-scale climate forcing and local forcing (i.e. SST, nutrients, surface winds). The local mechanistic underpinnings that are linked to large-scale climate forcing and ultimately constrain the interannual variability of phytoplankton biomass will be discussed (i.e. winter winds versus circulation changes).