Department Surface Waters - Research and Management

Primary production in Swiss lakes

The production of biomass from nutrients and light or chemical energy by algae and cyanobacteria is called primary production. It increases with the amount of available nutrients, in other words with the eutrophication of water bodies. The growth of biomass binds carbon, but its degradation consumes the oxygen in deep water. Primary production is thus one of the most fundamental and critical processes in lakes. However, their direct measurement is associated with great effort. Therefore, in practice, substitute variables are used, such as biomass or chlorophyll concentration. 

Alternatively, primary production can be estimated based on the available light and the absorption of this light by algae pigments. Both quantities can be determined on the one hand from optical satellite data and on the other hand from measurements taken by the LéXPLORE platform in Lake Geneva. On the basis of these data, we develop methods that allow the determination of daily and annual primary production in large Swiss lakes. We use novel hyperspectral data that will be available from 2024 as part of NASA’s PACE mission.