Sedimentary indicators of anthropogenic impact in Fildes Peninsula lakes (King George Island, Maritime Antarctica)

Fildes Peninsula, on King George Island, is among the Antarctic sites with the most intense human activity and is located in a region strongly influenced by global warming. While alterations to its once pristine environments have been noted, there is a lack of data concerning the region’s natural state before the increased human presence (∼1968). We studied seven lakes from Fildes Peninsula to assess anthropogenic effects on their ecological processes by studying pre- and post-anthropic sediments with a top-bottom approach. We examined differences in bacterial and phytoplankton communities using 16S rRNA metabarcoding, HPLC (high performance liquid chromatography) pigments and analysis of sediment metals. We observed lake-specific differences in bacterial communities between pre- and post-anthropic samples. Using indicator species analysis, we identified bacteria associated with polluted environments (e.g., KD4–96, Bacteroidetes vadinHA17, Hungateiclostridiaceae and Leptolinea) in post-anthropic sediments from two lakes that showed notable increases of metals. As both lakes are very close to roads and airport infrastructure, these associations may imply the greater recent presence of compounds including petroleum derivatives. Results indicated good preservation of bacterial DNA, but also that diagenetic processes may have affected pigment concentrations. Our data suggest that bacterial DNA may be used as a sedimentary proxy to reconstruct environmental changes including anthropogenic impacts in Antarctic lakes.