Spectral fluorescence: an ataxonomic tool for studying the structure of phytoplankton populations

Although early studies in plankton biology feature detailed analyses of numbers of species, modern studies tend to emphasize bulk changes in biomass associated with rare processes. We argue that the penalty for this approach will eventually be an incomplete understanding of seasonal and spatial changes in the pattern of primary production of ocean waters. The ability of natural populations to respond to changes in the marine environment is due to adaptability at the cellular level (phenotypic) and changes in whole species groups (genotypic). The inability to test the relative importance of these two strategies is due to the incompatiblity of traditional taxonomic approaches and field experimentation where rate processes are being measured. To counteract this difficulty we propose an ataxonomic technique which utilizes the differences in light absorption by phytoplankton for photosynthetic processes. In this report we review how changes in the fluorescence spectral signatures reflect other biochemical features in natural populations. This is examined in concert with physical and chemical changes associated with the characteristics of ocean water masses with specific reference as to how these hydrographic features influence the relative growth of phytoplankton populations.