.Contribution to the ecology of freshwater ostracodes (Crustacea) in Patagonia, Argentina.

VIEHBERG, F.A., CUSMINSKY, G., MARKGRAF, V. AND SCHWALB, A.

Guadalajara, México

Simposio; 11º International Paleolimnology Symposium; 2009

International Paleolimnology Association

The expansion of ecological species datasets of ostracodes and diatoms from South America will substantially improve the understanding of the biological proxies in sediment records and the interpretation of proxy signals in paleolimnological approaches. Here, we present results from coupled species abundance and water chemistry characteristics from 41 sites in Patagonia: Laguna Cari-laufquen area (41-41º30´S and 68º-69º W) and Lago Cardiel area (48º-49ºS and 70-71ºW). In Lago Cardiel we additionally tested the relationship between species abundances and water depth from a set of nine sediment surface samples following a water depths transect ranging between 5,5 and 32 m. Water samples were taken from each site and analyzed for temperature (ºC), pH, conductivity, as well as for major elements including Ca, Na, K, Mg, Cl, SO4, d18O and d13CDIC . Adult individuals of ostracodes and species assemblages were identified. We then applied multivariate statistics to our calibration dataset, which suggest that conductivity is the dominant factor in the ostracodes distribution within our dataset. A regression model (e.g., weighted average) can now be applied to infer quantitatively conductivity based on (fossil) ostracode assemblages.