title: Top consumer abundance influences lake methane efflux.
abstract: Lakes are important habitats for biogeochemical cycling of carbon. The organization and structure of aquatic communities influences the biogeochemical interactions between lakes and the atmosphere. Understanding how trophic structure regulates ecosystem functions and influences greenhouse gas efflux from lakes is critical to understanding global carbon cycling and climate change. With a whole-lake experiment in which a previously fishless lake was divided into two treatment basins where fish abundance was manipulated, we show how a trophic cascade from fish to microbes affects methane efflux to the atmosphere. Here, fish exert high grazing pressure and remove nearly all zooplankton. This reduction in zooplankton density increases the abundance of methanotrophic bacteria, which in turn reduce CH4 efflux rates by roughly 10 times. Given that globally there are millions of lakes emitting methane, an important greenhouse gas, our findings that aquatic trophic interactions significantly influence the biogeochemical cycle of methane has important implications.
authors.affiliation: Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35, 40014 Jyväskylä, Finland.
authors.forename: Shawn P
authors.initials: SP
authors.lastname: Devlin
authors.affiliation: Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35, 40014 Jyväskylä, Finland.
authors.forename: Jatta
authors.initials: J
authors.lastname: Saarenheimo
authors.affiliation: Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35, 40014 Jyväskylä, Finland.
authors.forename: Jari
authors.initials: J
authors.lastname: Syväranta
authors.affiliation: Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35, 40014 Jyväskylä, Finland.
authors.forename: Roger I
authors.initials: RI
authors.lastname: Jones
mesh_terms: D000818:Animals; D001419:Bacteria / Q000235:genetics*; D018533:Biomass; D057486:Carbon Cycle; D004269:DNA, Bacterial / Q000235:genetics*; D003621:Daphnia; D017753:Ecosystem; D005387:Finland; D005399:Fishes; D020387:Food Chain; D060106:Lakes / Q000737:chemistry* / Q000382:microbiology; D008697:Methane / Q000378:metabolism*; D010471:Perches; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics*; D015048:Zooplankton
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D008697:Methane