Methane-derived carbon flows through methane-oxidizing bacteria to higher trophic levels in aquatic systems.
Recent investigations have shown that biogenic methane can be a carbon source for macro invertebrates in freshwater food webs. Stable carbon isotopic signatures, used to infer an organism's food source, indicated that methane can play a major role in the nutrition of chironomid larvae. However, the pathway of methane-derived carbon into invertebrate biomass is still not confirmed. It has been proposed that chironomid larvae ingest methane-oxidizing bacteria (MOB), but this has not been experimentally demonstrated to date. Using (13)C-labelled methane we could show for the first time that chironomid larvae assimilate methane-derived carbon through MOB. Chironomid larval biomass was significantly (13)C-enriched after dwelling for 10 days in lake sediment enriched with labelled methane. Moreover, phospholipid fatty acids diagnostic for MOB were detected in larval tissue and were significantly (13)C-enriched, which encompasses the (13)C-uptake predicted for a methane-based nutrition. Additionally, chironomid larvae fed on sediment and water-column derived MOB biomass.
Deines
Peter
P
Max Planck Institute for Limnology, Department of Physiological Ecology, August-Thienemann-Strasse 2, 24306 Plön, Germany.
Bodelier
Paul L E
PL
Eller
Gundula
G
D000818:Animals; D018533:Biomass; D002247:Carbon Isotopes / Q000378:metabolism; D002683:Chironomidae / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism*; D020387:Food Chain; D005618:Fresh Water / Q000382:microbiology*; D019015:Geologic Sediments / Q000382:microbiology*; D007814:Larva / Q000378:metabolism; D008697:Methane / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism
D002247:Carbon Isotopes; D005227:Fatty Acids; D010743:Phospholipids; D008697:Methane