Our current state of knowledge on the effects of water flow on chemical exchange rates in benthic systems is primarily based on research conducted in still water or in unidirectional flow. However wave-driven oscillatory flow has recently been shown to play a major role in controlling chemical exchange rates in habitats such as coral reefs. Seagrasses, an important component of many shallow water ecosystems, pose a unique problem because they are flexible and can fill a significant portion of the water depth. In this project, researchers from Stanford University and University of South Florida will conduct the first systematic study of the velocity structure induced by oscillatory flow within natural canopies under a range of different wave conditions and canopy densities. They will conduct a detailed analysis of the mean and turbulent velocity structure within a Thalassia testudinum canopy under natural and controlled flow conditions to determine the effects of canopy morphological parameters (e.g. canopy density) on the flow structure. Additionally, this will be the first study to investigate in detail the coupling of the measured flow structure with simultaneous measurements of nutrient uptake rates by the entire canopy and organisms within the canopy under oscillatory flow conditions in situ. They will integrate flow field, light levels, physical canopy structure and community composition into a statistical-correlation type predictive model for nutrient uptake by individual community components, and ultimately entire canopy-forming communities. Their results will also have implications for other biological and chemical processes affected by small-scale hydrodynamics in shallow coastal systems.
Among the broader impacts is continued outreach to students at a Historically Black University that will increase the exposure of under-represented minorities to oceanography and increase the likelihood that they will pursue a career in academic science. Additional educational outreach programs include the production of three television programs, public outreach posters, and a curriculum for high school physics. In addition, the research will fund a post-doctoral fellow and two graduate students who will be cross-trained in the two laboratories.
