Paleoclimate reconstruction using isotopic analysis of tropical bivalves from the Pigeon Creek archaeological site, San Salvador Island, Bahamas

Abstract

This research investigates the paleotemperatures of the northeastern Bahamas by comparing oxygen isotope records constructed from modern and archeological specimens of Codakia orbicularis, collected on San Salvador, Bahamas. The stable isotope profiles for modern Codakia accurately recorded sea surface temperatures measured at Pigeon Creek lagoon. The ä18O values for the modern specimens ranged from –1.5 to +0.8‰ and averaged –0.2‰, while ä18O values for the archeological specimens ranged from –1.6 to +1.9‰ and averaged +0.2‰. The modern and the archaeological groups are isotopically distinct suggesting that sea surface temperature or the ä18O of surface waters differed between AD 1450 and today. The archaeological specimens had higher maximum ä18O values, which could reflect a cooler and/or drier climate in the past. In addition, the range of ä18O values for the archaeological samples is larger than the modern samples, suggesting that temperatures may have varied more widely on a seasonal temporal scale.