Modern chironomids (Diptera: Chironomidae) and the environmental variables that influence their distribution in the Araucanian lakes, south-central Chile

Detailed studies of Chironomidae fauna can yield a reliable tool to evaluate the effects of climatic change and anthropogenic disturbances over freshwater ecosystems. Using modern chironomid remains deposited in surface sediment samples of 27 lakes located in south-central Chile (37 degrees S-41 degrees S), we investigated the spatial distribution and diversity of chironomids in association with climatic and limnological variables. Linear methods and ordination analyses were used to select the best explanatory environmental variables that influence the diversity and distribution of chironomids among sites. We identified 52 chironomid taxa, highlighting Tanytarsini-tribe, Ablabesmyia, and Parapsectrocladius as the most common. Our results suggest air temperature as the most important and significant factor controlling the distribution of chironomids among the Araucanian lakes, followed by water temperature, and dissolved oxygen. The diversity of chironomids is negatively correlated with parameters related to lake productivity. Orthocladiinae and Podonominae subfamilies are most frequent in high-altitude lakes associated with cold temperatures, whereas Chironominae and Tanypodinae are characteristic of lowland-lakes influenced by higher temperatures. Human-induced contamination of freshwater ecosystems and the ongoing climate change in south-central Chile represent the main threat to macroinvertebrates communities, and therefore a challenge to predict the trajectories of chironomid assemblages in the near future.