OXYGEN ISOTOPE GEOCHEMISTRY OF THE FRESHWATER JUTE SNAIL (PACHYCHILUS SP.): A POTENTIAL ULTRA-LOCAL SEASONAL PALEOCLIMATE PROXY FOR TROPICAL MESOAMERICA

This paper will present preliminary results of an oxygen isotope study of the freshwater gastropod Pachychilus sp. Pachychilus sp., commonly known as the jute snail, is a fully-aquatic, stream-dwelling gastropod that can be found today in southern Mexico, the Yucatan peninsula, Guatemala, and Belize. Jute snails are abundant at Maya sites. In fact, it has been reported that over 100,000 individual jute specimens have been found at the Maya site of Pacbitun in western Belize. In addition to deposit at Maya settlements, deposits of jute snails have also been found in caves, potentially related to ritual behavior. The research proposed here has the potential to contribute not only to paleoclimate research, but it may also contribute to the archaeological record.

In areas where there is minimal seasonal temperature variation, such as Mesoamerica, it would be expected that δ¹⁸O variation observed in shell carbonate would be a reflection of seasonal variation in rainfall and evaporation, rather than seasonal temperature variation. It is hoped that this snail may serve as a proxy to assess past drought in direct archaeological context, thus giving insight into the role of drought in Maya prehistory.

The first stage of this research is the study of modern jute snail individuals to determine the genus’ growth patterns and seasonality. During recent fieldwork in the Cayo District of Belize, five modern jute specimens were collected. Two of the modern specimens were collected from Roaring Creek, while three specimens were collected from Barton Creek in western Belize. Several data loggers were deployed to monitor water temperature, and sequential water sample collections will be made for at least one year. Until these data are assembled, research will focus on general patterns of isotope distributions in these shells, as will be described in this presentation.