Phytoplankton patchiness and frontal regions

In the Chesapeake Bay estuary there are persistent seasonal frontal and interfrontal regions that serve to deliver and retain different phytoplankton populations. The patchiness of phytoplankton, both in total chlorophyll a concentrations and in species compositions and abundances, is shown to be causally related to density flow forcing which results in these frontal and interfrontal regions. The delineation of these regions by on-line, two-dimensional profiling of density isopleths serves to identify stations within these regions for biological and chemical sampling as opposed to sampling on an arbitrary geographical grid. It is possible, by superposition of nutrient and organism concentration isopleths upon salinity isopleths, to infer conservative and non-conservative features of the system.Contribution 1059 from the McCollum-Pratt Institute and Department of Biology. Research support by DOE contract DEASO2-76-EVO3278. The data in this paper have been presented at the Winter Meeting of the American Society of Limnology and Oceanography in Corpus Christi, Texas January 2–5, 1979 and the 42nd Annual Meeting of ASLO in Stony Brook, NY, USA June 18–21, 1979