Wind to zooplankton: Ecosystem-wide influence of seasonal wind-driven upwelling in and around the Delaware Bay

We synthesized historical records of wind, temperature, nutrients, phytoplankton, and zooplankton to produce a climatological view of the biological response to upwelling in an estuarine/coastal system, the Delaware Bay, and surrounding coastal ocean. We find a persistent, rather than episodic, impact of upwelling near the mouth of the bay from May to September. During the upwelling season, the average sea surface temperature for the upwelling region is 2-3 degrees C colder than the adjacent Delaware Bay and coastal ocean waters. This temperature difference is well correlated with the alongshore wind stress in the summer, making temperature a suitable upwelling index for the region. The upwelling apparently delivers subsurface nutrients to the lower bay and surrounding coastal ocean that help support phytoplankton primary production. Despite high primary production, the phytoplankton biomass (chlorophyll) does not increase accordingly. The lack of biomass increase is well correlated to seasonal increases in zooplankton biovolume. This result suggests that persistent upwelling near the Delaware Bay is characterized by an efficient transfer of carbon to primary consumers.