PEREZ Alejandra patricia
congresos y reuniones científicas
Patagonian lake drilling transect: Modern ostracods from Lago Cardiel and Laguna Cari-Laufquen area
CUSMINSKY, GABRIELA; SCHWALD, ANTJE; PÉREZ, PATRICIA; BURNS, STEPHEN; PATO PALATRAS TEAM MEMBERS
Mar del Plata, Argentina
Congreso; II Congreso Latinoamericano de Sedimentologia y VII Reunion Argentina de Sedimentologia; 2000
Asociación Argentina de Sedimentología e International Association of sedimentologists
Ostracods commonly found in freshwater and saline lakes are very useful indicators in paleoenvironmental reconstruction, especially for Quaternary environments. Modern ostracod assemblages from 26 sites including springs, spring pools, streams, ponds, lakes, and from a lake transect in the Lago Cardiel area (48¨¬S, 70-71¨¬ W) and in the Laguna Cari-Laufquen area (41¨¬S, 68-69¨¬ W) were studied. Preliminary results show that species abundance in Lago Cardiel area is low to high. Species diversity varies between 1 to 6 species per sample. Eucypris fontana (Graf), Limnocythere rionegroensis Cusminsky and Whatley, Limnocythere patagonica Cusminsky and Whatley, Eucypris virgata Cusminsky and Whatley, Cypridopsis sp., Heterocypris incongruens (Ramdohr), Eucypris aff. virgata, Candona sp., Iliocypris ramirezi Cusminsky and Whatley and Eucypris labyrinthica Cusminsky and Whatley and Darwinula sp. Newhmania sp. are present. In the Laguna Cari-Laufquen area the species abundance is high and its diversity varies between 4 and 7 species per sample. We found Limnocythere rionegroensis Cusminsky and Whatley, Eucypris fontana (Graf), Eucypris virgata Cusminsky and Whatley, Eucypris aff. virgata, Iliocypris ramirezi Cusminsky and Whatley, Limnocythere patagonica Cusminsky and Whatley, Eucypris labyrinthica Cusminsky and Whatley, Heterocypris incongruens (Ramdohr), Limnocythere sp. and Cypridopsis sp. The qualitative fauna analyzed in both areas is very similar but differs in species abundance: in the Lago Cardiel area Eucypris Fontana predominates while Limnocythere rionegroensis is the dominant specie in the Laguna Cari-Laufquen area. This hints at the different environmental conditions between both areas, with higher evaporation en the Laguna Cari-laufquen area than in the Lago Cardiel area. These observations are confirmed by the ¥ä18O and ¥ä13C signatures of the calcitic tests as well as the ¥ä18O signatures of the host waters (Schwalb et al., 1998). Modern ostracod fauna and their isotopic signatures will be used as a calibration set for future work on sediment cores from Lago Cardiel and Laguna Cari-Laufquen in order to understand the climatic variability during the Pleistocene and Holocene in Patagonia.