International Research Fellowship Program: Coupled Hydrodynamic and Biogeochemical Processes of Submerged Aquatic Vegetation

Branco Brett F, Groton CT

Investigators

Abstract

0601917 Branco The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad. This award will support a twenty-four-month research fellowship by Dr. Brett F. Branco to work with Dr. Carolyn Oldham at University of Western Australia in Crawley, Australia. Submerged aquatic vegetation (SAV) alters the flow field and vertical distribution of light, heat, nutrients, oxygen and other constituents in shallow systems. These coupled physical, chemical and biological dynamics determine SAV ecosystem function, stability and resiliency. However, mechanistic understanding and quantification of coupled processes in SAV ecosystems is lacking. The purposes of this work are to 1) identify and quantify the processes that affect the vertical transport of nutrients, oxygen, etc. across SAV canopies in a variety of shallow systems and 2) determine the impact of the transport processes on the recycling efficiency of nutrients below the SAV canopy. This work is being performed in coastal and inland waters of Western Australia representing three distinct aquatic environments: a river (unidirectional channel flow), a coastal bay (wave-dominated oscillatory flow) and a shallow lake (wind-mixed surface layer). Rates of vertical mass exchange between SAV canopies and overlying water will be measured in the field using fluorescent dye and 15N-labeled nutrient tracer studies. This work will produce: 1) a methodology for studying the coupled physical, chemical and biological processes in SAV ecosystems, 2) quantification of mass transfer across the SAV canopy as a function of system energy and energy dissipation, 3) quantification of nutrient recycling efficiency as a function of plant uptake rates and physical transport processes, 4) a new application for fiber optic fluorescent sensors in aquatic systems, and 5) identification of significant couples in determining SAV ecosystem stability and resiliency.