AN OSTRACODE-BASED TRANSFER FUNCTION FOR SAN SALVADOR ISLAND, BAHAMAS

High resolution records of past environments are needed to understand natural ecosystem variability and how global and regional changes in climate are reflected in local environments. A transfer function is a method of quantitative paleoenvironmental reconstruction whereby preserved microfossil assemblages are converted into an abiotic environmental variable of interest. This method depends on a strong correlation between modern assemblages and the abiotic environment that is then applied to preserved microfossil assemblages to produce a quantitative record of past abiotic factors such as salinity, temperature, or water depth. However, ecological processes such as dispersal limitation of individual species or physical factors like spatial autocorrelation of the abiotic environment could lead to overestimation of the precision of the correlation between species assemblages and the abiotic environment. We collected thirty modern ostracode assemblages and nineteen associated environmental variables from lakes on San Salvador Island, Bahamas. Neither individual abiotic factors, nor species abundances were spatially autocorrelated at the scale of the island. Additionally, change in assemblage composition was not related to distance separating lakes indicating ostracode species are not dispersal-limited at the scale of the island. Faunal change in ostracode assemblages was correlated with a complex hydrological gradient consisting of conductivity, lake area, and latitude with latitude probably representing an unmeasured precipitation gradient across the island. A transfer function was constructed for conductivity since changing conductivity of individual lakes has been linked to changes in climate and sea level. This transfer function has comparable precision to other published ostracode-based transfer functions for conductivity. It will be used to produce records of changing conductivity from lakes on San Salvador Island, Bahamas to understand how changes in regional climate and sea level affect past lake environments on San Salvador.