Primary Productivity in a Nutrient-Limited Tropical Estuary

Abstract

The results of a survey of phytoplankton productivity, chlorophyll a and nutrient concentrations in Pala Lagoon, American Samoa, are shown to be interpretable in terms of two regimes: an ocean-dominated region where productivity is controlled by fixed nitrogen concentrations, and a land-runoff-dominated regime where productivity is unrelated to major nutrient concentration. A quantitative relationship between nutrient concentrations in the lagoon and phytoplankton growth rates is presented. This relationship is used as the basis for predicting the effects of a proposed dredging operation within the lagoon as well as for predicting the effects of increased waste discharge into the local marine environment.