Characteristics and Anthropogenic Indications of Blue Hole Five, San Salvador, Bahamas
Lake sediment cores from three different sites in Blue Hole Five were collected in June 2012. One location was a deeper region near the conduit, another was an area of medium-depth, and the last was on the shallow bench. At each site, a dark green flocculent layer comprised the uppermost sediment, likely representing very recent human impacts such as vegetation clearance for the housing development. Sediments were composed almost exclusively of mollusk shells in some intervals, with little to no fine grained material, except towards deeper layers. Loss on ignition (LOI) results shows that the sediment is largely comprised of carbonate, with small amounts of organic material and even less inorganic material, probably deposited dust from a remote area. XRF data confirmed high levels of carbonate and strontium. SEM and smear slide observations showed an abundance of various mollusk shells and ostracodes. C. costata and A. auberiana mollusks were the most consistently dominant species throughout the first and last sites, although several other bivalve and gastropod species were present. Calcite, pyrite, diatoms, foraminifera, and iron oxides were discovered under microscopic examination. Evidence of charcoal, likely serving as a fire proxy, was also found in sediment layers. With a geologic record involving anthropogenic activity, Blue Hole Five will provide vital contrasting results with neighboring Bahamian blue holes in reconstructing climatic conditions.