OSTRACODES AS INDICATORS OF A YOUNGER DRYAS ENVIRONMENT AT THREE FOSSIL MASTODON SITES IN NEW YORK

Younger Dryas age freshwater ostracode assemblages recovered from mastodon (Mammut americanum) sites in New York differ from their modern counterparts found at those localities. Modern and fossil ostracode assemblages from the mastodon sites of Hyde Park, Dutchess County, North Java, Wyoming County, and Watkins Glen, Chemung County, New York, were examined along with their associated modern hydrochemical and climatic information. Radiocarbon dates obtained from the Hyde Park and Chemung skeletons were placed at approximately 11,500 and 12,100 radiocarbon years B.P., respectively.

Late Pleistocene/Early Holocene trench samples collected from Lozier Pond, Hyde Park, NY reveal the presence of the ostracode species Candona candida, Cyclocypris ampla, and Candona cf. bretzi collectively indicative of a cool, dilute, permanent groundwater discharge site during the Younger Dryas. Shifts in species occurrence and abundance are seen upon examination of modern sediments with Cypridopsis vidua, Cypria opthalmica, and Physocypria globula being the most prevalent of eleven total species found. Slightly warmer water with a greater contribution of shallow groundwater or surface flow, combined with an increase in subaquatic vegetation, is indicated by the dominance of these species and the marked decrease of C. candida and C. ampla. Lacustrine material attached to the bones of the North Java skeleton yielded five non-marine species, with the presence of C. ampla, C. candida, and Candona paraohioensis indicating cool, low-salinity waters located at the crest of this kame deposit. Forthcoming examination of sediments obtained from a core extracted at the Chemung mastodon site will likely provide added opportunities for paleoenvironmental analysis. Ongoing research using ostracode assemblages as a proxy for water chemistry, salinity, and temperature at these three sites will further show the environmental effects of the Younger Dryas in New York, and provide additional insight into the paleoecology of Late Pleistocene micro- and megafauna.