McGovern, T. Univ. of California, Santa Barbara, mcgovern@icess.ucsb.edu
Prezelin, B. University of California, Santa Barbara, barbara@icess.ucsb.edu
Kerfoot, J. University of California, Santa Barbara, kerfoot@lifesci.lscf.ucsb.edu
Gorga, J. University of California, Santa Barbara, gorga@lifesci.lscf.ucsb.edu
Robiart, J. C.. University of California, Santa Barbara, urobij01@mcl.ucsb.edu

 
IN SITU SPECTRAL RESPONSES OF COASTAL CALIFORNIA PHYTOPLANKTON TO REGIONAL AND SEASONAL VARIABILITY IN SOLAR UV RADIATION
 
During 1998, four cruises (February, June, September, and December) were conducted along coastal California. At one nearshore turbid and one clearer, warmer offshore station, drifters were deployed during each cruise to measure in situ phytoplankton responses to shorter and shorter wavelengths of ultraviolet radiation penetrating the water column. Our long-term goal is to determine seasonal and/or taxonomic based variability in UV biological weighting functions for in situ carbon fixation, pigmentation, and DOC excretion. Up to 4 drifters were simultaneously deployed at different depths and/or for different lengths of time. In each drifter, replicate phytoplankton communities were exposed to 8 spectral light treatments and changes in biomass, pigmentation, and primary production were measured. UV inhibition of production was always observed and, generally, the shorter the incubation, the greater the response. It was commonly observed that longer wavelengths of UV-A increased rates of production by up to 10% while shorter wavelengths of UV-A inhibited production by about the same amount. UV-B responses of phytoplankton largely controlled the overall UV inhibition of primary production in California coastal waters. This result is different from most Antarctic studies (cf. Prézelin et al. 1994, 1997) where UV-A inhibition accounted for the majority of overall UV inhibition.
 
Day: Wednesday, Feb. 3
Time: Poster
Location: Sweeney Center
 
Code: CS65WE1568S