PHYTOPLANKTON PRODUCTION AND BIOMASS ESTIMATES IN THE NORTHEAST ATLANTIC-OCEAN, MAY TO JUNE 1990

Time series measurements of size-fractionated chlorophyll alpha concentrations and primary production were made over the course of the spring bloom in and adjacent to a mesoscale eddy in the N.E. Atlantic as part of the U.K. Biogeochemical Ocean Flux Study 1990 Lagrangian Bloom Experiment, Substantial production, dominated by the >5 mu m and >1-5 mu m fractions, was recorded before the main growth phase of the bloom, although total chlorophyll a concentrations varied little over this period. The main growth phase of the bloom, which occurred over approximately one week, was dominated by the >1-5 mu m fraction; a principal constituent was the small diatom Nanoneis has[eae, which almost entirely displaced larger diatoms more typical of a spring bloom population. The >5 mu m phytoplankton fraction became dominant for approximately two weeks following the main bloom growth phase but was replaced at the end of the observation period by the >1-5 mu m and 0.2-1 mu m fractions. Phytoplankton taxonomic data for the 1990 bloom period were very different to the more typical bloom conditions of 1989. An intercomparison of C-14 production measurements made by U.K. and Dutch participants during the period of the Experiment using common samples gave total column productivities differing by <4%.