Phytoplankton release dissolved organic matter (DOM), a process traditionally viewed as unintentional and a disadvantage (i.e. loss of biomass). Recent observations suggest that phytoplankton purposefully produce/release DOM to support bacteria growing around them. Further, different phytoplankton species produce different DOM compounds that may attract specific bacteria that can perform a beneficial function (e.g. fix nitrogen). This mechanism is a missing link in our understanding of phytoplankton ecology and models, and limits our ability to manage harmful cyanobacteria blooms.

The purpose of this thesis project is to develop a mathematical model of the cross-feeding process. An existing AQUASIM model of Lake Zürich will be modified/extended to include the production of different DOM species, and a number of heterotrophic bacteria that specialize on these compounds. Model results will be compared to observed time series of phytoplankton species, DOM characteristics and heterotrophic species.

Contact: Prof. Ferdi Hellweger, ferdi.hellweger@tu-berlin.de [2], KF 306