Bacterial community responses to planktonic and terrestrial substrates in coastal northern Baltic Sea

Bacteria are major consumers of dissolved organic matter (DOM) in aquatic systems. In coastal zones, bacteria exposed to a variety DOM types originating from land and open sea. Climate change is expected cause increased inflows freshwater the northern which may lead either eutrophication or inputs refractory terrestrial compounds. The compositional functional response bacterial communities such changes not well understood. We performed 2-day microcosm experiment two bays Baltic Sea, where we added plankton extract simulate soil Our results showed that responded differently food substrates but similar way both bays. Plankton addition induced community composition, while no significant occurred treatments. Gammaproteobacteria were promoted by extract, Alphaproteobacteria dominated non-amended controls. Carbohydrate metabolism genes, as aminoglycan chitin degradation, enriched extract. conclusion, rapidly highly bioavailable substrates, had minor influence degraded slowly. Thus, if climate leads eutrophication, large composition function can be expected, inflow will show fast changes. Degradation instead occur over longer periods time, e.g. years. These findings help better understand ability utilize different carbon sources their role ecosystem.