Berndt, H. L. University of Maryland-CES/Horn Point Laboratory, berndt@hpl.umces.edu
Fisher, T. L. University of Maryland-CES/Horn Point Laboratory, fisher@hpl.umces.edu

 
THE EFFECTS OF WATERSHED NUTRIENT INPUTS ON ESTUARINE ALGAL COMMUNITIES IN THE CHOPTANK RIVER TRIBUTARY OF THE CHESAPEAKE BAY, USA
 
We examined the spatial relationships between nutrient inputs and turbidity from the Choptank River watershed, and the phytoplankton population densities and community structure in the adjacent estuary. Nutrient concentrations were determined, and algal pigment concentrations were examined using HPLC. The relative chlorophyll contribution of phytoplankton groups was determined with the CHEMTAX program, and corroborated with microscopy. Elevated NH4 and PO4 were found in the vicinity of point source inputs and were frequently associated with elevated chlorophyll, indicative of high algal biomass. These point source effects were superimposed upon a background of highly turbid, nutrient-rich waters in the upper estuary, where algal biomass exhibited high seasonal variability, while the lower estuary was relatively nutrient-poor, less turbid, and had less variable total biomass. However, algal biomass in the upper estuary was light-limited during many months of the year, despite high nutrient concentrations from non-point source inputs. Between stations there were small spatial variations in the proportions of algal classes, and diatoms dominated throughout the year. Seasonally, dinoflagellates were more abundant in summer, while cryptophytes were more abundant during the winter. Even in this rural area, dominated by agricultural diffuse sources, small point sources have discernible effects in terms of nutrients and phytoplankton.
 
Day: Wednesday, Feb. 3
Time: 10:30 - 10:45am
Location: Sweeney Center
 
Code: CS59WE1030S