The Response of Nutrients and CO2 to Wind-Driven Coastal Upwelling Measured During the CoOP-WEST study

Newly upwelled water may have initial pCO2 concentrations two to three times higher than atmospheric values with correspondingly high nitrate and silicate concentrations. With aging of this water the biological pump plays an important role in reducing these concentrations as chlorophyll phytoplankton biomass is produced. pCO2 may be reduced to values well below atmospheric values, and nutrients depleted to near detection levels. Nutrient and pCO2 data were collected during underway surveys modes in the upwelling area near Bodega Bay, California during the CoOP WEST study. High levels of pCO2 (> 1000 μatm) and surface nutrients (nitrate > 40 μM, silicate > 50 μM) were observed during the Spring 2000 and 2002 cruises, which were characterized by persistent winds and strong upwelling. In spring 2001 upwelling was less intense with concurrently lower concentrations of pCO2 and nutrients. The winter cruise (January 2002) showed low concentrations of nutrients and no elevated pCO2 concentrations. The fate of pCO2 and nutrients in these different years will be discussed in the context of the coastal phytoplankton community.