Dr. Matthew C Schwartz

Submarine groundwater discharge (SGD) is the process by which fresh or brackish groundwater moves through porous sediments to the surface water. SGD is a method of transportation for different nutrients, metals, pollutants, and freshwater to enter our coastal waters. Tidal pumping and sub-surface hydraulic pressure are the key driving forces that move groundwater through the land-sea interface. At high tide, porewater in the subterranean estuary (STE) is predicted to have a low concentration of nutrients due to seawater recirculation. During the ebb tide, SGD through the STE will cause nutrient concentrations to increase. The objective of this study is to observe how porewater nutrient concentrations are impacted by tides at an SGD positive zone. The area of study is located at the Gulf Islands Nation Seashore: Naval Live Oaks Preservation Area in Santa Rosa County, Florida. The area of interest ranges from the shoreline to about 30 meters offshore in Santa Rosa Sound. Previous research has indicated this site as an SGD positive through radon isotope analysis. Piezometers are inserted into the sediment on the seafloor at different depths to extract groundwater. The transects of porewater extent to three different distances away from shore to show the movement of groundwater. Elevated nutrient levels are present in the subterranean estuary. The nutrient concentrations appear to have spatial variability but are showing changes as the tidal cycle progresses. Collecting evidence of nutrients moving through a subterranean estuary and interacting with the SGD interface can provide a better understanding of tidal pumping and the impacts that it can have on an aquatic ecosystem.

Submarine groundwater discharge (SGD) is a hydrological phenomenon of terrestrial groundwater entering coastal surface waters through porous sediments. While past research has analyzed SGD nutrient influxes, the distributions of seagrasses relative to SGD, and more, this research aims to connect SGD inputs to the ecological responses of Thalassia testudinum, a seagrass commonly known as turtle grass. More specifically, we are investigating the impact of SGD-transported nutrients into the local environment (including porewaters and bottom waters) in which Thalassia is growing by analyzing for variations in elemental abundance and stable isotope composition of seagrass in areas receiving SGD as compared to control areas in which no SGD is measured. We sampled eight site locations within Florida's Gulf Islands National Seashore's Naval Like Oaks (NALO) Preserve for bottom-water nitrate, nitrite, ammonium and phosphate; physical water quality parameters (dissolved oxygen, specific conductivity, temperature, pH, and turbidity); and dissolved radon. Additionally, Thalassia testudinum seagrass samples were collected from all stations for IRMS analysis for delta (super 15) N and delta (super 13) C to investigate SGD influences on C:N ratios and stable isotope composition in the local seagrasses, including spatial and tidal controls on any variability in water column chemistry and seagrass biogeochemistry. Preliminary stable isotope results from selected pilot sites showed a substantial difference in delta (super 15) N and delta (super 13) C between Thalassia rhizomes and leaves; however, they did not show stable isotope differences between SGD and non-SGD sites within the study area. We have added additional sampling sites to those pilot sites to further identify the relationship between SGD and seagrass biogeochemistry at the NALO site.

In recent years, alternative strategies for shoreline armoring have become increasingly popular with coastal property owners. In Northwest Florida, local agencies implemented plans to attenuate wave action and reduce landward shore recession in an urban bayou by installing living shorelines. Living shorelines are constructed in the inter-tidal zones and incorporate both hard and soft structured stabilization. Generally, the hard component is fossilized oyster shells and the soft component is planted intertidal vegetation, such as Spartina alterniflora (Smooth cordgrass) and Juncus roemererianus (Black needlerush). Living shorelines were intended to comprise both ecological and societal implications by significantly slowing erosion processes for property owners, by utilizing oyster beds to improve water quality, and by fostering new ecological habitats in the marsh grasses. The issue presented with living shoreline management is long-term studies have not been carried out on these engineered systems. For this study, geospatial technology was utilized to create 3D images of terrain by interpolation of data points using a TotalStation to compute geomorphic change. Additionally, water samples were analyzed using traditional wet chemistry laboratory methods to determine total oxidized nitrogen (TON), ammonium, and orthophosphate content in water. Over a short three-month preliminary study, sediment accretion was observed primarily within the vegetation with the bulk of the erosion occurring around the oyster beds. TON was detected at levels between 10 mu M and 30 mu M, ammonium up to 5 mu M, and orthophosphate was only detected in very low levels, consistently < 2 mu M. The project is in its infancy, as the topographic profiles and water quality data will be used to establish baseline data for future research to determine volumetric geomorphic change,and to set a standard for water quality trends, surrounding oyster beds and vegetation in response to climatic events.

A research project initiated by faculty from a community college and a nearby regional comprehensive university has provided faculty and students from both institutions with a variety of educational and research opportunities. The continuing project assessing harmful algal bloom dynamics in NW Florida has prospered due to the synergy between faculty and students pursuing separate, but mutually beneficial goals within the research collaboration. The coastal biogeochemistry project was launched two years ago in an estuarine site that is located in close proximity to the Northwest Florida State College (NWFSC), a community college with a two-year science program, and is built upon an existing research project being performed by University of West Florida (UWF) faculty and graduate students. NWSFC students actively participate in both field collection and lab processing of samples and provide manpower for the project and NWFSC lab facilities close to the field site benefit the project by facilitating high sampling frequency. UWF graduate students provide continuity between field seasons and access to UWF's advanced research analytical capabilities that are not available at NWFSC. As such, the project depends on the interaction of parties (faculty and student) from both institutions and prospers where the individual institutions would likely fall short. The research project has been incorporated into NWFSC courses, is related to at least two UWF master's theses, and was the foundation for a funded NSF research grant and additional research proposals with NWFSC and UWF personnel as PIs. Additionally, the collaborators are a married couple and this project has provided an opportunity to deal with the challenge of being a couple with two academic careers in the same discipline.