Recently, in Obersee (Glarus), a lake in the Swiss Alps, the cyanobacteria Tychonema was observed using Elodea as a substrate. Elodea is an invasive plant capable of producing allelopathic compounds that inhibit the growth of other microorganisms, including cyanobacteria. The goal of my Master’s project is to find out whether this association also occurs in other Swiss alpine lakes, and how Elodea and Tychonema influence each other. To address these questions, I will combine field sampling and co-culture experiments in the laboratory.