Reconstructing the effects of anthropogenic activities and climate change in three lakes of the Fildes Peninsula, Maritime Antarctic

The Fildes Peninsula (maritime Antarctica) is greatly affected by global warming and local human impacts since it is in one of the Antarctic regions with the highest intensity of human activity. To establish the effect of human activities on Fildes Peninsula lakes, we compared trends in diatom assemblages, bacterial communities and metal concentrations in sediment cores from two lakes close to human infrastructure with those in a more remote lake. In the two lakes close to stations and the airport, we found heavy metal enrichments and diatom teratologies, as well as notable changes in diatom assemblages in one of these lakes, roughly coincident with the time when the first two stations were built (~ 1970). Due to the known association between diatom teratologies and metal enrichment, metal stress is a convincing explanation for these changes. Certain bacterial taxa determined to be indicators of pollution were also found to be more abundant in the impacted lakes in recent sediments (i.e., Hungateiclostridiacea e , OPB41, Anaerovorax and Leptolinea ). Metal, diatom and bacteria changes observed in the lake more distant to infrastructure were more subtle and are likely related to climate change alone. Given the proximity of the affected lakes to the airport and roads, our data suggests that transportation infrastructure and activity on Fildes Peninsula is likely a key cause of contamination in the region’s ecosystems. This study provides important insights into how human activities and climate change have affected Fildes Peninsula aquatic ecosystems and how they may respond to future stressors.