CS29 Phytoplankton & Primary Production
Date: Monday, June 10, 2002
Time: 10:45:00 AM
Location: Oak Bay
 
Banse, Oceanography, University of Washington, Seattle, Wa 98195, , banse@oceanography.washington.edu
 
STEEMANN NIELSEN AND THE ZOOPLANKTON, AND WHY DO WE CONTINUE TO MEASURE C14-UPTAKE AND PHOTOSYNTHESIS OF PHYTOPLANKTON?
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A principal goal of ecology is to understand and be able to predict the abundance of organisms and its temporal change. Did Steemann Nielsen, who introduced the C14-method in 1952, believe that this goal in terms of phytoplankton carbon can be achieved by only measuring and understanding photosynthesis? As to be shown by citations, he apparently did not, but he thought principally of the vast regions of the open oligotrophic seas with little temporal change of phytoplankton abundance, where the gain from cell division and the loss mainly from grazing are balanced on an almost daily basis. Using Cushing's North Sea CALANUS patches of 1949 and 1954 and the two low-latitude iron fertilization experiments (IronEx I, II) of the1990's, I will show that the sentiment holds also during the development of phytoplankton blooms: The majority of the newly formed cells is lost every day. In the open sea and, presumably, large lakes, the rates of cell divi-sion (INSTEAD of photosynthesis by itself) AND of mortality are needed for understanding phytoplankton abundance and its temporal change, including the sign of change.