REGULATION OF ESTUARINE PRIMARY PRODUCTION BY WATERSHED RAINFALL AND RIVER FLOW

Enhanced phytoplankton production and algal blooms, symptoms of eutrophication, are frequently caused by elevated nutrient loading, usually as nitrogen, to coastal waters. This nitrogen is derived primarily from anthropogenic sources (urban, industrial, and agricultural) but is delivered to coastal waters through meteorological and hydrological means. We utilized a 4 yr monthly data set to investigate the effect of these upstream physical forces upon primary productivity of the Neuse River Estuary (North Carolina, USA), a large temperate coastal plain estuary. Our results indicate that the magnitude of estuarine primary production and the periodicity of algal blooms can be directly related to variations in upper watershed rainfall and its subsequent regulation of downstream river flow. Future changes in precipitation patterns for coastal regions may thus lead to substantial alterations in coastal primary productivity rates and patterns.