Tyler, A. C.. University of Virginia, tyler@virginia.edu
McGlathery, K. C.. University of Virginia, kjm4k@virginia.edu
Anderson, I. C.. Virginia Institute of Marine Sciences, iris@vims.edu

 
THE INFLUENCE OF MICRO- AND MACROALGAE ON DON FLUXES IN A SHALLOW COASTAL LAGOON
 
Dissolved organic nitrogen is an important and often ignored component of the nitrogen pool in coastal ecosystems. The objective of this study was to determine how benthic microalgae and the common macroalgae, Ulva lactuca, regulate sediment water fluxes of DON. Studies were performed across a gradient of organic matter inputs in Hog Island Bay, a shallow lagoon of the Virginia Coast Reserve Long Term Ecological Research Site. Seasonal measurements of DO, DIC, DIN and DON fluxes were made during light and dark incubations of sediment cores with and without U. lactuca. DON fluxes exceeded DIN fluxes and the sediments were a significant source of DON to the water column. Light-dark differences in fluxes indicate that microalgae have an impact on DON fluxes, and cross-site differences reflect the variation in microalgal production. The lack of DON fluxes in the dark in cores containing U. lactuca may indicate dark uptake of DON. Highest flux rates were observed following die-off of a large macroalgal bloom. Algae are important in controlling fluxes of DON across the sediment-water interface in this system, implying that they play a significant role in regulating transformations and fluxes of N from the lagoon to the coastal ocean.
 
Day: Monday, Feb. 1
Time: 04:00 - 04:15pm
Location: Sweeney Center
 
Code: SS45MO0400S