In Search of Submarine Groundwater Discharge into Seagrass Beds along the Gulf Coast of Northwest Florida

Submarine groundwater discharge (SGD) is described as groundwater flowing from land into water in coastal environments via a submerged shoreline. Determining the spatial distribution of SGD flux is important because this hydrologic flux can have a significant influence on nutrient and water volume input into coastal environments.

The objectives of this study were to identify locations of submarine groundwater discharge, and to determine if there was a relationship between the spatial distribution of SGD and the seagrass beds along the coast of the Naval Live Oaks Preserve, Santa Rosa County, Florida. Surface water and groundwater samples were taken to determine nutrient concentrations in nearshore groundwater as well as near depth surface water over seagrass beds. Nutrient analysis was done initially to begin looking for variability in the water composition. Identification of possible SGD sites was done via detection of naturally occurring radioisotopes, Rn-220 and Rn-222 using a RAD7 instrument. From this study, most of the possible SGD sites were identified nearshore within the study area, especially within the approximately 10 meters closest to shore based on elevated Rn-220 and Rn-222 concentrations. Despite a possible correlation between higher radon signals and seagrass beds from visual reviews of the data, the relationship between seagrass and SGD distribution are still indeterminate for the study area.