THE EFFECTS OF TEMPORAL VARIABILITY OF MIXED-LAYER DEPTH ON PRIMARY PRODUCTIVITY AROUND BERMUDA

Temporal variations in primary production and surface chlorophyll conc entrations, as measured by ship and satellite around Bermuda, were sim ulated with a numerical model. In the upper 450 m of the water column, population dynamics of a size-fractionated phytoplankton community we re forced by daily changes of wind, light, grazing stress, and nutrien t availability. The temporal variations of production and chlorophyll were driven by changes in nutrient introduction to the euphotic zone d ue to both high- and low-frequency changes of the mixed layer depth wi thin 32-degrees-34-degrees-N, 62-degrees-64-degrees-W between 1979 and 1984. Results from the model derived from high-frequency (case 1) cha nges in the mixed layer depth showed variations in primary production and peak chlorophyll concentrations when compared with results from th e model derived from low-frequency (case 2) mixed layer depth changes. Incorporation of size-fractionated plankton state variables in the mo del led to greater seasonal resolution of measured primary production and vertical chlorophyll profiles. The findings of this study highligh t the possible inadequacy of estimating primary production in the sea from data of low-frequency temporal resolution and oversimplified biol ogical simulations.