DYNAMICS OF A SUBMARINE GROUNDWATER DISCHARGE FROM A SPRING IN THE KARSTIC LIMESTONE COCKBURN TOWN FORMATION, SAN SALVADOR, BAHAMAS

San Salvador is Pleistocene to Holocene aged Karstic carbonate island in the Bahamian island chain. The island is dominated by brackish and saline interior lakes with smaller areas of fresh groundwater and localized coastal submarine groundwater discharge. The temperature, salinity, and conductivity were recorded in the opening vent of a brackish submarine spring in the south coast of the island 24 hours in June of 2014 using a remote sonde. Temperature, salinity, and conductivity varied in a semidiurnal pattern matching the tidal signal. The lowest salinities of 24 psu and the lowest temperatures of 27.02°C were observed with the lowest tide, and the highest salinity of 29.3 psu and temperature of 28.1°C were observed during the highest tides. This indicates that the SGD in the spring vent system is tidally driven with the highest discharge occurring at low tide and the lowest discharge occurring at high tide. This was confirmed with observations of visual schiller effect during the low tides at the spring vent mouth. Two component mixing analysis indicates at maximum spring discharge freshwater constitutes 32% of all discharge and at minimum spring discharge 16% of all discharge. This freshwater influx may be locally important to sessile flora and fauna in the discharge area of the vent, and may represent a large version of a more widespread phenomenon on the island.