ENVIRONMENTAL SIGNIFICANCE OF THE OXYGEN ISOTOPE COMPOSITION OF TROPICAL LAND SNAILS FROM TRINIDAD ISLAND

Land snails might be the most abundant terrestrial invertebrates found in great numbers in the Quaternary sedimentary record. Their shells are often well preserved in a variety of conditions conductive to both paleontological and archeological research. As a result, they have the potential to provide invaluable local paleoenvironmental information. Many published modern calibration studies in the middle latitudes of the northern hemisphere have shown that the stable oxygen isotopes (δ¹⁸O) of snail shells appear to serve as proxy for environmental water δ¹⁸O values. However, tropical latitudes have received minimal attention for this purpose, even though snail shells are plentiful across archeological and paleontological deposits in the Caribbean islands.

This study calibrates the δ¹⁸O values of several small species of modern land snails from Trinidad Island (latitude: 10.6918° N, longitude: 61.2225° W) for use as paleoclimate proxies in the tropics. Modern snail shells were collected along an east-to-west environmental gradient, isotopically analyzed and compared to instrument climate data. Results suggest that most species overlapped in oxygen isotope values, and no significant isotopic variations were documented between coastal and inland sites. This work illustrates that tropical land snails primarily track the local precipitation δ¹⁸O values. Therefore, ancient shells of these species may be used as proxies to infer changes in precipitation δ¹⁸O throughout the Quaternary in the Caribbean region.