Ostracods, stable isotopes (delta(18)oxygen and delta(13)carbon and the paleoecological reconstruction of coastal and lacustrine environments in Florida over decadal and millennial time scales

Two independent studies demonstrate the usefulness of fossil ostracods and their δ18O and δ13C values to resolve specific paleoenvironmental and paleohydrological problems over decadal to millennial timescales. The first study presents a 100+ paleoenvironmental reconstruction of three sites in the lower Everglades: Oyster Bay, adjacent to Shark River Slough; an accreting mudbank southwest of Jimmy Key, and an extensive, shallow mudbank in western Florida Bay. These reconstructions are based on an extensive ostracod-ecological database derived from analyses of surficial sediment samples collected in Florida Bay and published literature. Variations in ostracod abundance and diversity, as well as in their historical δ 18O and δ13C values indicate shifts in “optimal” and “stressful” environmental conditions through time as a result of the complex overprint of natural seasonal fluctuations in climate, and anthropogenic modifications of the environment over the 20th Century. The second study presents a 10,200-yr paleohydrological reconstruction of a sinkhole lake in west central Florida based on temporal fluctuations in ostracod assemblages and their δ18O and δ 13C values. These fluctuations document relative changes in water temperature and hydrologic characteristics of the lacustrine system that are the result of warming air temperatures, changes in the relative contributions of input waters (shallow vs. deep groundwater), rainfall patterns and relative sea level rise during the Holocene.