| Abstract | The contribution of oxic methane production to greenhouse gas emissions from lakes is
globally relevant, yet uncertainties remain about the levels up to which methanogenesis can
counterbalance methanotrophy by leading to CH4 oversaturation in productive surface
waters. Here, we explored the biogeochemical and microbial community variation patterns in
a meromictic soda lake, in the East African Rift Valley (Kenya), showing an extraordinarily
high concentration of methane in oxic waters (up to 156 micromol L-1
). Vertical profiles of
dissolved gases and their isotopic signature indicated a biogenic origin of CH4. A bloom of
Oxyphotobacteria co-occurred with abundant hydrogenotrophic and acetoclastic methano-gens, mostly found within suspended aggregates promoting the interactions between Bacteria, Cyanobacteria, and Archaea. Moreover, aggregate sedimentation appeared critical in
connecting the lake compartments through biomass and organic matter transfer. Our findings
provide insights into understanding how hydrogeochemical features of a meromictic soda
lake, the origin of carbon sources, and the microbial community profiles, could promote
methane oversaturation and production up to exceptionally high rates. |
| Authors | Fazi S.[1,11], Amalfitano S.[1,11], Venturi S.[2,3], Pacini N.[4,5], Vazquez E.[6], Olaka L.A.[7], Tassi F.[2,3], Crognale S.[1], Herzsprung P.[8], Lechtenfeld O.J.[8], Cabassi J.[3], Capecchiacci F.[2,3], Rossetti S.[1], Yakimov M.M.[9], Vaselli O.[2,3], Harper D.M.[5,10], Butturini A.[6] |
| Text | 455383 2021 10.1038/s42003 021 02365 x Scopus 2 s2.0 85109372622 East African Rift Valley Kenya ; High concentrations of dissolved biogenic methane associated with cyanobacterial blooms in East African lake surface water Fazi S. 1,11 , Amalfitano S. 1,11 , Venturi S. 2,3 , Pacini N. 4,5 , Vazquez E. 6 , Olaka L.A. 7 , Tassi F. 2,3 , Crognale S. 1 , Herzsprung P. 8 , Lechtenfeld O.J. 8 , Cabassi J. 3 , Capecchiacci F. 2,3 , Rossetti S. 1 , Yakimov M.M. 9 , Vaselli O. 2,3 , Harper D.M. 5,10 , Butturini A. 6 1 Water Research Institute, National Research Council of Italy IRSA CNR , Monterotondo, Rome, Italy; 2 Department of Earth Sciences, University of Florence, Florence, Italy; 3 Institute of Geosciences and Earth Resources, National Research Council of Italy IGG CNR , Florence, Italy; 4 Department of Environmental Engineering, University of Calabria, Arcavacata di Rende, Rende, Italy; 5 University of Leicester School of Geography, Geology and the Environment, Leicester, UK; 6 Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Barcelona, Spain; 7 Department of Geology, University of Nairobi, Nairobi, Kenya; 8 Helmholtz Centre for Environmental Research UFZ , Leipzig and Magdeburg, Germany; 9 Institute for Marine Biological Resources and Biotechnology, National Research Council of Italy IRBIM CNR , Messina, Italy; 10 Freshwater Biological Association, Far Sawrey, Ambleside, England, UK; 11 These authors contributed equally Stefano Fazi, Stefano Amalfitano The contribution of oxic methane production to greenhouse gas emissions from lakes is globally relevant, yet uncertainties remain about the levels up to which methanogenesis can counterbalance methanotrophy by leading to CH4 oversaturation in productive surface waters. Here, we explored the biogeochemical and microbial community variation patterns in a meromictic soda lake, in the East African Rift Valley Kenya , showing an extraordinarily high concentration of methane in oxic waters up to 156 micromol L 1 . Vertical profiles of dissolved gases and their isotopic signature indicated a biogenic origin of CH4. A bloom of Oxyphotobacteria co occurred with abundant hydrogenotrophic and acetoclastic methano gens, mostly found within suspended aggregates promoting the interactions between Bacteria, Cyanobacteria, and Archaea. Moreover, aggregate sedimentation appeared critical in connecting the lake compartments through biomass and organic matter transfer. Our findings provide insights into understanding how hydrogeochemical features of a meromictic soda lake, the origin of carbon sources, and the microbial community profiles, could promote methane oversaturation and production up to exceptionally high rates. 4 Published version https //www.nature.com/commsbio/ Yakimov M.M. 9 9 Institute for Marine Biological Resources and Biotechnology, National Research Council of Italy IRBIM CNR , Messina, Italy High concentrations of dissolved biogenic methane associated with cyanobacterial blooms in East African lake surface water FAZI_July_2021.pdf Articolo in rivista Springer Nature 2399 3642 Communications biology Communications biology Communications biology Commun. biology orlandovaselli VASELLI ORLANDO francotassi TASSI FRANCO francescocapecchiacci CAPECCHIACCI FRANCESCO VENTURI STEFANIA simona.rossetti ROSSETTI SIMONA stefano.fazi FAZI STEFANO stefano.amalfitano AMALFITANO STEFANO jacopo.cabassi CABASSI JACOPO simona.crognale CROGNALE SIMONA |
