My research addresses the chemical and trophic ecology of aquatic systems, with a particular focus on freshwater habitats. A central theme is the importance of essential fatty acids for the fitness and reproduction of aquatic herbivores, studied from gene expression to the population level. Closely linked to this is ecological stoichiometry, i.e., how nutrient ratios between primary producers and consumers shape their growth, feeding, and interactions. Another focus is chemical communication in aquatic environments: volatile organic compounds (infochemicals) as signals between algae and their consumers, including how environmental stressors such as ocean acidification and climate change affect this communication. In addition, I work on stream and river ecosystems, particularly the structure and function of biofilms, nutrient cycling, and the effects of restoration measures as well as anthropogenic stressors (pollutants, invasive species) on food webs. Methodologically, I use laboratory and field experiments (e.g., in flume mesocosms) combined with the analytical chemistry of VOC and lipids, and stable isotope analysis to study ecological processes across environmental gradients. Overall, I aim to relate organisms and their adaptive response to properties of the whole ecosystem such as biodiversity, food web structure, trophic transfer or matter and energy to gain a better understanding of ecosystems' structure and functions.