title: Climate-related changes of soil characteristics affect bacterial community composition and function of high altitude and latitude lakes.
abstract: Lakes at high altitude and latitude are typically unproductive ecosystems where external factors outweigh the relative importance of in-lake processes, making them ideal sentinels of climate change. Climate change is inducing upward vegetation shifts at high altitude and latitude regions that translate into changes in the pools of soil organic matter. Upon mobilization, this allochthonous organic matter may rapidly alter the composition and function of lake bacterial communities. Here, we experimentally simulate this potential climate-change effect by exposing bacterioplankton of two lakes located above the treeline, one in the Alps and one in the subarctic region, to soil organic matter from below and above the treeline. Changes in bacterial community composition, diversity and function were followed for 72 h. In the subarctic lake, soil organic matter from below the treeline reduced bulk and taxon-specific phosphorus uptake, indicating that bacterial phosphorus limitation was alleviated compared to organic matter from above the treeline. These effects were less pronounced in the alpine lake, suggesting that soil properties (phosphorus and dissolved organic carbon availability) and water temperature further shaped the magnitude of response. The rapid bacterial succession observed in both lakes indicates that certain taxa directly benefited from soil sources. Accordingly, the substrate uptake profiles of initially rare bacteria (copiotrophs) indicated that they are one of the main actors cycling soil-derived carbon and phosphorus. Our work suggests that climate-induced changes in soil characteristics affect bacterioplankton community structure and function, and in turn, the cycling of carbon and phosphorus in high altitude and latitude aquatic ecosystems.
authors: Lake and Glacier Ecology Research Group, Institute of Ecology, University of Innsbruck, Technikerstraße 25, Innsbruck, Austria.
authors: Carina
authors: C
authors: Rofner
authors: Lake and Glacier Ecology Research Group, Institute of Ecology, University of Innsbruck, Technikerstraße 25, Innsbruck, Austria.
authors: Hannes
authors: H
authors: Peter
authors: Limnology, Department of Ecology and Genetics, University of Uppsala, Uppsala, Sweden.|Catalan Institute for Water Research (ICRA), Emili Grahit 101, Girona, 17003, Spain.
authors: Núria
authors: N
authors: Catalán
authors: Lake and Glacier Ecology Research Group, Institute of Ecology, University of Innsbruck, Technikerstraße 25, Innsbruck, Austria.
authors: Fabian
authors: F
authors: Drewes
authors: Lake and Glacier Ecology Research Group, Institute of Ecology, University of Innsbruck, Technikerstraße 25, Innsbruck, Austria.
authors: Ruben
authors: R
authors: Sommaruga
authors: Lake and Glacier Ecology Research Group, Institute of Ecology, University of Innsbruck, Technikerstraße 25, Innsbruck, Austria.
authors: María Teresa
authors: MT
authors: Pérez
mesh_terms: D000531:Altitude; D001419:Bacteria; D044822:Biodiversity; D002980:Climate; D057231:Climate Change; D060106:Lakes; D012987:Soil; D012988:Soil Microbiology
chemical_list: D012987:Soil
keywords: allochthonous organic carbon; bacterial production; dissolved organic matter; diversity; heterotrophic; phosphorus limitation; terrestrial vegetation; treeline