Zooplankton Community Structure in the North Sea and Northeast Atlantic: Development and Test of a Biological Model

Abstract

A simulation model was used to examine whether predatory interactions may regulate the size structure of marine zooplankton communities, as observed in many freshwater systems. Results of the model were consistent with the freshwater studies, such that large increases or decreases in planktivorous fish led to the dominance of small or large zooplankters, respectively. However, model predictions were not consistent with the recent decline in the northeastern Atlantic of most major elements of the pelagic zooplankton community along with North Sea herring and mackerel stocks. The overall decline of the pelagic community throughout this region indicates that zooplankton abundance may be regulated by physical forcing, and that these populations may be food- rather than predator-limited. Realistic ecological simulations of marine pelagic systems may require more complex two-layer models allowing for the effects of vertical migration, and with day–night differences in food availability and selectivity.