Sedimentary bacterial markers from Lake Montcortes

We investigate long-term shifts in the oxygenation regime of meromictic lake Montcortes (LM) and concomitant microbiological changes since 1500 BP. The annually laminated sediments of LM allow for accurate and detailed dating and reliable reconstructions of biological communities and redox conditions. Also, its meromictic character makes it an excellent model system for our purpose, since the presence of long-lasting anoxia in the monimolimnion provides a stable environment where well-developed anaerobic communities should prevail. The goals of this study are: to reconstruct the fluctuations of the volume of anoxic hypolimnetic waters of LM using redox proxies from the lacustrine sediment, to reconstruct the succession of subfossil microbiological communities through the content of bacterial 16S rRNA since 1500 BP, to seek relationships of past responses of microbiological communities with selected anoxia indicators and with potential anoxia drivers, and to anticipate the future evolution of the lake ecosystem in terms of deoxygenation, in the frame of climate forcing induced by global warming.