Autotrophic production, biomass and species composition at two stations across an upwelling front

In early September 1989 persistent southward winds generated an upwelling region along the Oregon coast with an upwelling front at its seaward edge. Chl a concentrations were higher in cold water nearshore, and a deep chl a maximum was present offshore. On both sides of the front, production rates were highest above 10% I_o, but the integrated rate nearshore was higher by a factor of 3, and the energy conversion efficiency (from incident solar energy to fixed chemical) of the euphotic zone at the landward station was more than twice that of the seaward station. The larger and brighter peak was caused by cryptomonads; this peak was absent seaward of the front. At the productive inshore station Synechococcus spp., cryptomonads and small autotrophs (<10μm) dominated the phytoplankton biomass, and diatoms were a relatively minor component. -from Authors