Benthic microalgae are a central component of shallow coastal habitats and they may account for a significant fraction of the total primary production in these ecosystems. While several factors act in concert to generate the high photosynthetic rates observed in benthic microalgae, available data suggest light is of primary importance. Nutrient availability may also be important because increasing human population in the coastal zone has led to an oversupply of nutrients to aquatic habitats, in particular estuaries. The present study focused on the effects of light and nutrients on benthic primary production at two coastal Georgia sites: the Duplin River and the Satilla River. Benthic primary production and biomass along the Duplin varied over space and time. Nutrient addition experiments led to increased primary production by benthic microalgae (indicating nutrient limitation) with the addition of nitrogen and phosphorus at Sapelo Island but not at the Satilla River site.
