Impacts of human activities and climate on Lake Morenito, Northen Patagonia, Argentina

MAUAD, MELINA; MAYR, CHRISTOPH; GRAßE, TERESA; DUBOIS, NATHALIE; SERRA, MARIA NOEL; FRANCO GAVIRIA, JUAN FELIPE

Stockholm

Conferencia; Joint meeting of the International Paleolimnology Association and the International Association of Limnogeology; 2018

For more than 50 years, Lake Morenito, located in the city of Bariloche in the Nahuel Huapi National Park (Argentina), has been exposed to anthropogenic impacts including damming, house-building, species introduction, tourism, and probably climate change. An 80 cm-long sediment core spanning more than 100 years from L. Morenito was studied for chironomid larvae, stable isotopes, and organic geochemistry to resolve how natural and anthropogenic stressors impacted the lake. The core chronology is based on 210Pb and 137Cs activities. Chironomid assemblages display major changes around AD 1950. The appearance of the warm adapted Chironomus and the replacement of Apsectrotanypus by Ablabesmyia indicate a shift to warmer conditions. Chironomid composition changes again in AD 1960, post-damming and after the deposition of volcanic tephra, followed by slow recovery of several taxa. At this time, a change in the sediment accumulation took place possibly linked to increased erosion during and after damming. However, for most of the core, low TOC/TN values (