Warming and eutrophication interactively drive changes in the methane-oxidizing community of shallow lakes

Thomas P A Nijman; Thomas A Davidson; Stefan T J Weideveld; Joachim Audet; Chiara Esposito; Eti E Levi; Adrian Ho; Leon P M Lamers; Erik Jeppesen; Annelies J Veraart

doi:10.1038/s43705-021-00026-y

Warming and eutrophication interactively drive changes in the methane-oxidizing community of shallow lakes

ISME Commun. 2021 Jul 5;1(1):32. doi: 10.1038/s43705-021-00026-y.

Authors

Thomas P A Nijman¹, Thomas A Davidson^{2

3}, Stefan T J Weideveld⁴, Joachim Audet^{2

3}, Chiara Esposito^{2

3}, Eti E Levi^{2

3}, Adrian Ho⁵, Leon P M Lamers⁴, Erik Jeppesen^{2

3

6

7

8}, Annelies J Veraart⁴

Affiliations

¹ Department of Aquatic Ecology and Environmental Biology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands. tom.nijman@ru.nl.
² Lake Group, Department of Bioscience and Arctic Research Centre, Aarhus University, Silkeborg, Denmark.
³ WATEC Aarhus University Centre for Water Technology, Aarhus University, Silkeborg, Denmark.
⁴ Department of Aquatic Ecology and Environmental Biology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands.
⁵ Institute for Microbiology, Liebniz Universität Hannover, Hannover, Germany.
⁶ Sino-Danish Centre for Education and Research (SDC), University of Chinese Academy of Sciences, Beijing, China.
⁷ Limnology Laboratory, Department of Biological Sciences and Centre for Ecosystem Research and implementation, Middle East Technical University, Ankara, Turkey.
⁸ Institute of Marine Sciences, Middle East Technical University, Erdemli-Mersin, Turkey.

Abstract

Freshwater ecosystems are the largest natural source of the greenhouse gas methane (CH₄), with shallow lakes a particular hot spot. Eutrophication and warming generally increase lake CH₄ emissions but their impacts on the sole biological methane sink-methane oxidation-and methane-oxidizer community dynamics are poorly understood. We used the world's longest-running freshwater climate-change mesocosm experiment to determine how methane-oxidizing bacterial (MOB) abundance and composition, and methane oxidation potential in the sediment respond to eutrophication, short-term nitrogen addition and warming. After nitrogen addition, MOB abundance and methane oxidation potential increased, while warming increased MOB abundance without altering methane oxidation potential. MOB community composition was driven by both temperature and nutrient availability. Eutrophication increased relative abundance of type I MOB Methyloparacoccus. Warming favoured type II MOB Methylocystis over type I MOB Methylomonadaceae, shifting the MOB community from type I dominance to type I and II co-dominance, thereby altering MOB community traits involved in growth and stress-responses. This shift to slower-growing MOB may explain why higher MOB abundance in warmed mesocosms did not coincide with higher methane oxidation potential. Overall, we show that eutrophication and warming differentially change the MOB community, resulting in an altered ability to mitigate CH₄ emissions from shallow lakes.