The relation between productivity, disturbance and the biodiversity of Caribbean phytoplankton: applicability of Huston's dynamic equilibrium model

This study tests the predictions of Huston's dynamic equilibrium model of species richness. It examines field data showing the effects of silicates/disturbance and productivity on the number of coexisting species within a functional type (diatoms) in a community. Using multivariate statistical techniques, the pattern of phytoplankton species richness throughout the Caribbean islands is modelled in relation to overlapping gradients of silicates/disturbance and primary productivity originating from the Amazon and Orinoco rivers. Data were obtained from 44 Caribbean, South and Central American oceanographic stations sampled during the Caribbean Oceanographic Resources Exploration (CORE) of 1990. The results of the study give support to Huston's dynamic equilibrium hypothesis, which predicts maximum species richness under conditions of intermediate productivity and disturbance. Fishery statistics for the region show that the diversity of harvested marine species of commercial importance is a mirror of the diversity of the phytoplankton. Some consequences of global environmental change to the dynamic equilibrium of the allocation of fishery resources between small Caribbean states are discussed.