TY - JOUR

T1 - Methane cycling in lake sediments and its influence on chironomid larval δ13C

AU - Eller, Gundula

AU - Deines, Peter

AU - Grey, Jonathan

AU - Richnow, Hans-Hermann

AU - Krüger, Martin

PY - 2005/11/1

Y1 - 2005/11/1

N2 - Stable carbon isotope analysis of chironomid larvae gave rise to the hypothesis that methane-oxidizing bacteria can provide an important food source for higher trophic levels in lakes. To investigate the importance of the methane cycle for the larval stable carbon signatures, isotope analysis and microbiological and biogeochemical investigations were combined. The study was based on comparison of a dimictic lake (Holzsee) and a polymictic, shallow lake (Großer Binnensee), both located in northern Germany. Both lakes are inhabited by Chironomus plumosus larvae, which exhibited a stronger 13C-depletion in Holzsee than in Großer Binnensee, indicating a greater contribution of methane–carbon in the former. Indeed, the processes involved in the microbial methane cycle were found to be more active in Holzsee, showing higher potential methane production and methane oxidation rates. Consistently, cell numbers of methane-oxidizing bacteria were with 0.5 − 1.7 × 106 cells Embedded Image about one order of magnitude higher in Holzsee than in Großer Binnensee. Molecular analysis of the microbial community structure revealed no differences in the methanotrophic community between the two lakes, with a clear dominance of type I methanotrophs. The methanogenic population seemed to be adapted to the prevailing substrate in the respective lake (H2/CO2 in Holzsee and acetate in Großer Binnensee), even though differences were minor.In conclusion, the stronger larval 13C-depletion in Holzsee was not reflected in differences in the microbial community structure, but in the activity and size of the methanogenic and methanotrophic populations in the lake sediment.

AB - Stable carbon isotope analysis of chironomid larvae gave rise to the hypothesis that methane-oxidizing bacteria can provide an important food source for higher trophic levels in lakes. To investigate the importance of the methane cycle for the larval stable carbon signatures, isotope analysis and microbiological and biogeochemical investigations were combined. The study was based on comparison of a dimictic lake (Holzsee) and a polymictic, shallow lake (Großer Binnensee), both located in northern Germany. Both lakes are inhabited by Chironomus plumosus larvae, which exhibited a stronger 13C-depletion in Holzsee than in Großer Binnensee, indicating a greater contribution of methane–carbon in the former. Indeed, the processes involved in the microbial methane cycle were found to be more active in Holzsee, showing higher potential methane production and methane oxidation rates. Consistently, cell numbers of methane-oxidizing bacteria were with 0.5 − 1.7 × 106 cells Embedded Image about one order of magnitude higher in Holzsee than in Großer Binnensee. Molecular analysis of the microbial community structure revealed no differences in the methanotrophic community between the two lakes, with a clear dominance of type I methanotrophs. The methanogenic population seemed to be adapted to the prevailing substrate in the respective lake (H2/CO2 in Holzsee and acetate in Großer Binnensee), even though differences were minor.In conclusion, the stronger larval 13C-depletion in Holzsee was not reflected in differences in the microbial community structure, but in the activity and size of the methanogenic and methanotrophic populations in the lake sediment.

KW - Carbon cycle

KW - Carbon stable isotopes

KW - Methanogenesis

KW - Archaea

KW - Methanotroph

KW - Chironomid larvae

U2 - 10.1016/j.femsec.2005.04.006

DO - 10.1016/j.femsec.2005.04.006

M3 - Journal article

VL - 54

SP - 339

EP - 350

JO - FEMS Microbiology Ecology

JF - FEMS Microbiology Ecology

SN - 0168-6496

IS - 3

ER -