Presented by Dr. Chris Houser, Associate Professor, Department of Geography, Texas A&M University

Abstract: Barrier island transgression in response to sea level rise is accomplished during storms capable of scarping or overtopping the vegetated foredune, which in turn depends on the height and extent of the dune relative to the elevation of the storm surge. The foredune can, however, exhibit considerable variability alongshore, which leads to a more complex island response to and recovery from tropical storms and hurricanes. As an example, the alongshore variation of the geomorphology and ecology of Santa Rosa Island in northwest Florida is shown to be forced by a ridge and swale bathymetry on the inner continental shelf. It is argued that the ridge and swale bathymetry is a transgressive surface and the remnants of the seagrass and marsh dominated cuspate spits along the modern back-barrier shoreline. In this respect, the cuspate spits had to first develop along the back-barrier shoreline and eventually evolve into the mud-cored ridges as the island transgressed with relative sea-level rise. Once the ridge and swale bathymetry emerged on the modern (Gulf of Mexico) shoreface it is able to reinforce the alongshore variation in dune height and storm response, which in turn controls the location and extent of island ecosystems including backbarrier marshes, seagrass beds and maritime forest. The geomorphology and ecology of this island is, therefore, an expression of a large-scale biophysical feedback and suggests a top-down model in which meso-scale system behavior is depend on the geologic context. Island resiliency and stability with relative sea level rise and a change in storm activity is dependent on the management of the backbarrier habitat and post-storm dune recovery.

Biography: Dr. Houser is an Associate Professor in the Department of Geography and has a research focus on biophysical feedback mechanisms in coastal and aeolian systems. With support from the National Park Service a large part of his research is focused on the geomorphology and ecology of barrier island systems in support of park management. Dr. Houser is also the Director for the NSF REU Site: Ecohydrology of a Tropical Montane Cloud Forest in central Costa Rica and is the first Global Faculty Ambassador for Texas A&M University in support of research and education programs at the Soltis Center in Costa Rica.

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