Carbon cycle in lakes

Lakes, and inland waters in general, play a remarkable role in the global carbon cycle. In those ecosystems production, storage, transformation and consumption of carbon are activities mainly mediated by microorganisms. We studied the organic carbon cycle in prealpine and alpine lakes and quantified the total organic carbon standing stock (TOC) both as dissolved (DOC) and particulate (POC) forms (Bertoni and Callieri 1989; Callieri and Bertoni 1999; Callieri et al. 1999; Bertoni et al. 2010). The in-lake processes cause quantitative and qualitative changes of the organic carbon pool, greatly affecting the different trophic levels in the food chain.

In the last years we focused our attention on the Transparent Exopolymer Particles (TEP). This fraction in Lake Maggiore can reach 56% of TOC in the photic layer, while it never exceed 2% in the hypolimnion, below 200 m depth. TEP are driven by chlorophyll a and can increase in lakes as a consequence of the ongoing climate changes (Callieri et al. 2017, 2019).