T105 Surf’s Up: New Insights on the Geology, Karst, and Paleontology of Carbonate Systems of the Bahama Archipelago (Posters)

Monday, 5 November 2012
9:00 AM - 6:00 PM
Hall B

CHARACTERISTICS AND ANTHROPOGENIC INDICATIONS OF WATLING'S BLUE HOLE, SAN SALVADOR ISLAND, BAHAMAS

Paper number: T105-4
Program: Technical Sessions
Time: 9:00 AM – 6:00 PM

Authors

Abstract

San Salvador, Bahamas is a small carbonate island which contains many blue holes. Among these is Watling’s Blue Hole, which is located in the southwest corner of the island in the center of a failed housing development. A rock fence, 0.5 – 1.7 meters in height surrounds the blue hole and a series of four pens that extend into the lake are located on the northeast side. The walls were established by local residents in the 1800’s and perhaps thereafter and have had important impacts on the landscape.

Watling’s blue hole was cored in June 2012 to explore climate change and anthropogenic impacts. Its water depth and salinity vary seasonally and it is connected to the ocean through a conduit, which creates a tidal range of 0.6 – 0.9 meters. The shallower depths of Watling's contain sea grass, algae, and several species of bivalves and gastropods. The bottom of the lake, which is approximately 8 meters deep, slopes gently towards the center with a steep drop towards the conduit, located at the center of the lake. The bedrock underlying the lake continues to dissolve during marine lowstands. The bottom water is anoxic since ocean water entering through the conduit is rarely in contact with the atmosphere and it is also has marine salinity. The cores yield a record of diatoms, ostracodes, foraminiferans, and mollusks. The presence of the mollusk Acteocina sp. is a water depth and sea level indicator because it is found in deep waters. X-ray fluorescence (XRF) data shows that Titanium (Ti), routinely used as a proxy for siliciclastic input to lake sediments, is very low in these cores; however as iron (Fe) and Ti correlate throughout the core, iron may also be used as a proxy for dust. Ongoing research on Watling’s will provide excellent data for sea level, climate change, and anthropogenic impacts.