Primary production and grazing in the plankton of the Panama Bight

Measurements of chlorophyll a, pheopigments, primary production and zooplankton were made during the deployment cruise of the Sediment Trap Intercomparison Experiment (STIE) to the Panama Bight (5°20′N, 81°55′W) in August 1979. Integral chlorophyll a levels over the euphotic zone averaged 20.3 mg m⁻² and were not significantly different from day to day. Daily rates of primary production varied widely (200–700 mg C m⁻² day⁻¹). Phaeopigment levels were high, and on a molar basis, roughly equivalent to the amount of chlorophyll a in the euphotic zone. Zooplankton were most abundant in the top 100 m; dominant groups were cope pods, ostracods and chaetognaths. Estimates of macro- and microzooplankton grazing suggest that primary production and consumption were in balance on a time scale of a few days, and that microzooplankton were responsible for the bulk of the grazing impact.