Seagrass ecosystems comprise highly productive regions of the coastal ocean that have declined dramatically in abundance over the past several decades. While losses can be attributed to a variety of factors, including ocean warming and disease, the primary threat appears to be from anthropogenic changes to water quality. The proposed research will be composed of measurements to determine large-scale circulation and micro-scale fluid processes impacting sediment suspension and oxygen fluxes surrounding seagrass communities with the aim of understanding how hydrodynamic processes, and in particular wave-action, may ultimately impact pollutant and particulate transport and benthic respiration. Although previous studies have focused on hydrodynamics of seagrasses, information on how wave-dominated flows impact particulate and dissolved chemical transport within these seagrass ecosystems, and to adjacent coastal environments, is sorely lacking. Research within tropical seagrass ecosystems will be carried out at two sites along the Atlantic coast of Panama, one a disturbed and the other a relatively pristine system. Temperate seagrass research will be conducted along the Virginia, USA coast at the Virginia Coast Reserve-Long Term Ecological Research (VCR-LTER) station, where there are ongoing efforts to reestablish a viable seagrass community within the coastal bays.
The intellectual merit of the proposed research resides in establishing a better understanding of flow and turbulent mixing processes within wave-dominated environments and how local and large-scale hydrodynamics affect the ecology of seagrass communities. In doing so, this research will help advance our knowledge of (1) how the physical structure of seagrass beds alter the retention and dispersion of sediments within coastal ecosystems, (2) how wave-dominated flow over and through benthic plant structures alters the flux of oxygen across the sediment-water interface, and (3) how alterations to these environments, through changes in seagrass cover, land use and eutrophication, affect micro- and macro-scale chemical and particulate transport. Integral to this work will be the development of new instruments and techniques to quantify mixing and mass transport in wave-dominated environments that can also be applied broadly to many other coastal ecosystems.
The broader impact of this research resides in its contribution to understanding hydrodynamic-biological interactions within important yet vulnerable marine ecosystems. Within Virginia, measurements will quantify the impact of seagrasses on wave attenuation and sediment resuspension to determine the extent to which seagrass expansion has altered the bay from a net erosional environment to one that promotes deposition of suspended sediment, thereby reducing light attenuation and creating a positive feedback for seagrass growth. Hydrodynamic and chemical flux measurements in healthy and degraded seagrass beds in Panama, combined with analysis of historical changes to on-shore mangrove and off-shore coral reef cover, will determine the impact of land-use and eutrophication on ecosystem processes. The education plan for this project includes in-depth classroom, field and laboratory research experiences for high school to graduate-level students. Collaboration with the VCR-LTER Schoolyard program will involve high school students and teachers in the monitoring of water quality in local harbors and coastal bays, which directly integrates with the proposed research. International outreach, through a University of Virginia/Panama initiative, will include developing and teaching an interdisciplinary course in Panama that brings together U.S. and Panamanian students to study environmental policy and marine conservation. Student progress in both the Virginia high school and Panama courses will be monitored through use of a Web-based Interactive Science and Engineering (WISE) learning tool. WISE is an online science-learning environment that provides for real-time collaboration and assessment of student's understanding of core concepts. An online curriculum will be developed for marine sciences where students will input and analyze their data, compare and contrast findings from U.S. and Panamanian seagrass communities, and learn about the benefits of and threats to coastal ecosystems.
