Littoral zones are overlooked in the continental carbon cycle

Inland waters have a strong effect on climate because they emit greenhouse gases (GHG) to the atmosphere, both carbon dioxide and the highly potent gas methane (CH4), and store organic carbon (OC) in their sediments.

Inland waters are fringed with belts of aquatic plants (macrophytes) in near-shore (littoral) areas, and even though their global carbon (C) turnover is higher than that of phytoplankton, they are completely ignored from current conceptualizations of the inland water C cycle.

Fragmented studies suggest that CH4 emissions and OC sequestration can be very high but also extremely variable between different macrophyte species, however we can at present not explain this variability.

I aim to develop a new framework for littoral GHG emissions and OC sequestration by defining novel climate functional types of macrophytes, which quantify the effect on climate of macrophyte species based on species-specific traits.

To do so, I will measure GHG emissions and OC sequestration for different macrophyte species in a laboratory experiment (Aim 1, yr 1) and in-situ in shallow lakes (Aim 2, yr 2).

In addition, I will assess in two contrasting lakes how much of the open-water GHG emissions are in fact derived from the littoral zone (Aim 3, yr 3).

This project will fill a large gap in our current understanding of the C cycling on the continents and contribute to a more robust quantification of role of inland waters in global C budgets.