Smith, W. O.. Virginia Institute of Marine Sciences, 804-684-7293
Barber, R. O.. Duke University Marine Laboratory,
Hiscock, M. Duke University Marine Laboratory,
Marra, J. Lamont Doherty Earth Observatory,
Mathot, S. Virginia Institute of Marine Science,

Four cruises to the Ross Sea in 1996/1997 were completed as part of the Southern Ocean JGOFS experiment. Our objective was to assess the seasonal cycle of growth, biomass and productivity of phytoplankton to assess the potential environmental controls on primary productivity. Positive phytoplankton growth began in late october, and by early november productivity reached 0.5 g C m-2 d-1. Biomass and productivity increased rapidly thereafter, becoming maximal during early december. Chlorophyll concentrations exceeded 15 ug l-1 at some stations during this period. During the summer productivity reached 2 g C m-2 d-1, but both biomass and productivity decreased rapidly in mid-february. Little or no productivity was observed in march and april, consistent with the extremely low biomass levels observed. A comparison of in situ and simulated in situ incubations strongly suggest that on-deck incubations bias estimates of productivity by inducing photoinhibition, which was not observed within in situ incubations. Additional data from other cruises are consistent with the overall magnitude of the seasonal bloom, but variations may occur in timing both of the onset of growth and of the maximum, as well as the spatial pattern of productivity.
Day: Wednesday, Feb. 3
Time: 04:45 - 05:00pm
Location: Sweeney Center
Code: SS31WE0445S