Abundance and biogeography of methanogenic and methanotrophic microorganisms across European streams
Authors: Nagler Magdalena , Praeg Nadine , Niedrist Georg H. , Attermeyer Katrin , Catalán Núria , Pilotto Francesca , Gutmann Roberts Catherine , Bors Christoph , Fenoglio Stefano , Colls Miriam , Cauvy‐Fraunié Sophie , Doyle Brian , Romero Ferran , Machalett Björn , Fuss Thomas , Bednařík Adam , Klaus Marcus , Gilbert Peter , Lamonica Dominique , Nydahl Anna C. , Romero González‐Quijano Clara , Thuile Bistarelli Lukas , Kenderov Lyubomir , Piano Elena , Mor Jordi‐René , Evtimova Vesela , deEyto Elvira , Freixa Anna , Rulík Martin , Pegg Josephine , Herrero Ortega Sonia , Steinle Lea , Bodmer Pascal 
Published: December 2020

Aim

Although running waters are getting recognized as important methane sources, large‐scale geographical patterns of microorganisms controlling the net methane balance of streams are still unknown. Here we aim at describing community compositions of methanogenic and methanotrophic microorganisms at large spatial scales and at linking their abundances to potential sediment methane production (PMP) and oxidation rates (PMO).

Location

The study spans across 16 European streams from northern Spain to northern Sweden and from western Ireland to western Bulgaria.

Taxon

Methanogenic archaea and methane‐oxidizing microorganisms.

Methods

To provide a geographical overview of both groups in a single approach, microbial communities and abundances were investigated via 16S rRNA gene sequencing, extracting relevant OTUs based on literature; both groups were quantified via quantitative PCR targeting mcrA and pmoA genes and studied in relation to environmental parameters, sediment PMP and PMO, and land use.

Results

Diversity of methanogenic archaea was higher in warmer streams and of methanotrophic communities in southern sampling sites and in larger streams. Anthropogenically altered, warm and oxygen‐poor streams were dominated by the highly efficient methanogenic familiesMethanospirillaceae,MethanosarcinaceaeandMethanobacteriaceae, but did not harbour any specific methanotrophic organisms. Contrastingly, sediment communities in colder, oxygen‐rich waters with little anthropogenic impact were characterized by methanogenicMethanosaetaceae,MethanocellaceaeandMethanoflorentaceaeand methanotrophicMethylococcaceaeandCd. Methanoperedens. Representatives of the methanotrophicCrenotrichaceaeandMethylococcaceaeas well as the methanogenicMethanoregulaceaewere characteristic for environments with larger catchment area and higher discharge. PMP increased with increasing abundance of methanogenic archaea, while PMO rates did not show correlations with abundances of methane‐oxidizing bacteria.

Main conclusions

Methanogenic and methanotrophic communities grouping into three habitat types suggest that future climate‐ and land use changes may influence the prevailing microbes involved in the large‐scale stream‐related methane cycle, favouring the growth of highly efficient hydrogenotrophic methane producers. Based on these results, we expect global change effect on PMP rates to especially impact rivers adjacent to anthropogenically disturbed land uses.