NON-MARINE OSTRACODES AND THE MULTI-PROXY APPROACH-- REGIONAL AND HEMISPHERIC CHANGES IN QUATERNARY HYDROCLIMATOLOGY (Invited Presentation)

The multi-proxy approach to paleoecological analysis was championed by Herb Wright, a powerful advocate for developing large databases for Quaternary Studies. Mutual Climatic Range (MCR) methods for ostracodes reconstruct past air temperatures, facilitating comparison with other proxies, but have hitherto relied on databases such as NODE in Europe and NANODe in the USA which, on their own, fail to capture fully many species’ distribution. As non-marine ostracode databases for large regions of the Northern Hemisphere become widely available (see www.neotomadb.org and www.biofresh.org) they are being united via the Ostracod Metadatabase of Environmental and Geographical Attributes (OMEGA). Harmonization of these datasets continues, but preliminary mapping of species’ distributions in Holarctic view reveals changing conditions of surface hydrology with climate forcing through the Quaternary.

Cytherissa lacustris identifies permanent, cold, freshwater habitats in Plio-Pleistocene and Holocene time slices in North America and Europe, showing its southernmost extent during the MIS2 glacial and retreating northwards during the Late Glacial and early Holocene. Cytherissa lacustris and Candona caudata have co-occurred since the Pliocene and today are found in permanent, freshwater lakes in North America and Europe (Clementsian distribution). Limnocythere ceriotuberosa and L. bradburyi co-occurred in the North American Pleistocene but dispersed into different climatic zones in the Holocene (Gleasonian distribution).

Such distributions facilitate valuable hydrologic and temperature reconstructions for archaeological interpretation, e.g. at the British MIS11 human occupation site at West Stow where new calibration of L. suessenbornensis, taxonomically harmonized with North American L. friabilis, suggests a previously unrecognized cold start for the interglacial. A multi-proxy approach applies the mutual climatic range method to determining the narrowest possible temperature range within which all available proxy assemblages could have coexisted. Preliminary results for the MIS9 interglacial in Britain, incorporating ostracode, beetle, pollen and plant macrofossils, fish and herpetiles, indicate a more continental climate than today, with a modern analogue in northern Germany.