Effect of nitrogen fertilization on the activity and diversity of methane oxidising bacteria in the littoral zone of a boreal lake

Freshwater lakes are generally net sources of CH4 and in boreal lakes a major part of the CH4 emissions originates from the littoral zone during the ice-free season. Aerobic CH4 oxidising bacteria, methanotrophs, significantly limit the flux of CH4 to the atmosphere from sediments. Increased N load causes eutrophication and subsequent anoxia, which probably enhances CH4 production. In addition, inorganic nitrogen (ammonium and nitrate) can inhibit CH4 oxidation. Our study belongs to the research consortium METHECO (Eurodiversity programme of European Science Foundation), where the activity and diversity of methane oxidising bacteria are studied in various European ecosystems.