DEVELOPMENT OF A DATASET TO ASSESS FRESHWATER OSTRACODE RESPONSE TO LATE-HOLOCENE CLIMATES IN THE UPPER MIDWEST

Environmental and ostracode assemblage data were collected from 33 lakes in Wisconsin, Minnesota and Iowa in July 2013 for the purpose of developing a calibration dataset to quantify past climate in the region. Data for these sites, collected between 1987 and 1994, were available from the Neotoma Paleoecology Database, affording the unique opportunity to investigate changes in water quality and freshwater ostracode assemblages over the past 25 years. Multivariate analyses of the environmental data indicate that lakes located on the prairies and in the prairie-forest ecotone have undergone changes in water chemistry, whereas lakes in the coniferous forest have exhibited few changes. Ostracode assemblage data for the two sampling periods will be presented and causes of the observed differences in the aquatic ecosystems between the two periods will be discussed. Future work involving expansion of the dataset and application to the fossil record will also be addressed.