CONICET | Buscador de Institutos y Recursos Humanos

As most species are stenotopic and respond rapidly to environmental changes, Chironomidae have been widely used as (paleo)ecological indicators in the Northern Hemisphere to document changes in parameters such as lake productivity and mean air temperature. This bioproxy shows great promise for assessing climate change in South America. However, the lack of information on their taxonomy and modern ecology in remote areas such as Southern Patagonia hinder the construction of robust models for quantitative environmental reconstructions. Our main goal is to contribute to the development of a neontological biodiversity and ecological database for paleoenvironmental interpretation purposes in southern Patagonia. The study area comprises lakes from Andean and ecotonal settings at Los Glaciares National Park and the Patagonian steppe, where climate is dry, cold and windy. Twelve surface sediment samples obtained from lakes located between ~69°W and ~73°W were analyzed. Larval head capsules were picked under stereomicroscope from the >150 µm fraction. Selected physico-chemical variables of the host waters were analyzed in order to determine their role in the assemblages? structure. The relationship between these variables and the species composition was explored by linear-based ordination methods (RDA and PCA) and the diversity was estimated with the Shannon-Wiener index using the CANOCO© 5.03 software. A total of 47 taxa were found, of which 25 occurred with relative abundances > 5% in at least one sample; diversity varied between 0.49 and 2.42 (S = 3 ? 13) and tended to be higher in waterbodies located in Andean settings. There is some evidence that total organic carbon (TOC), total nitrogen (TN) and altitude, which is directly related to precipitation regime, could be relevant in explaining the assemblages composition, being statistically non-significant (Monte Carlo Test; p = 0.07) but only marginally so. Taxa such as Cricotopus are more abundant in lakes with lower TOC and higher TN (relative to the dataset), while taxa such as P. accuminatus predominate in waterbodies of opposite characteristics. For their part, Limnophyes and Smittia tend to be more abundant in lakes at higher altitude, and therefore higher water availability. Further sampling of the study area would allow a better characterization of the underlying gradient and a more precise estimation of the Patagonian chironomids? ecology.