Evaluation of factors controlling methanogens and methane-oxidizing bacteria on hydropsychid caddisfly retreats

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Matthew R. Monteverde (Creator)
The University of North Carolina at Greensboro (UNCG )
Web Site: http://library.uncg.edu/
Anne Hershey

Abstract: Biogenic methane is produced in aquatic sediments by methanogenic Archaea, and captured by methane-oxidizing bacteria (MOB), thereby cycling methane into food webs. Preliminary work has shown that net-spinning caddisfly (Trichoptera: Hydropsychidae) retreats and nets support methanogens and MOB, which are consumed by hydropsychids. We evaluated whether these microbes are incidental on retreats and nets (captured during filter feeding), or if retreat and net microhabitats facilitate their growth. Field data showed that methanogens in hydropsychid foreguts and on retreats were positively associated with seston and sediment methanogen populations, but varied with genus, while net methanogens were also associated with seston but not sediment. Hydropsyche nets and retreats were more associated with seston and Cheumatopsyche retreats were more associated with sediment. For MOB, Hydropsyche retreat populations also were more strongly associated with seston MOB, while Cheumatopsyche MOB retreat populations were more closely associated with sediment MOB. But, net MOB populations were not associated with either seston or sediment. These differences may reflect differences in retreat construction and stream microhabitat. In a lab experiment, hydropsychid foregut and net MOB densities were highest in the experimental treatment containing sediment plus methane, and lowest in the treatment with no sediment and equilibrium methane concentration. These results suggest that nets facilitate MOB growth, but that a sediment source may be needed to establish or maintain MOB populations on retreats. It also suggests that MOB are responding to a local methane source produced by methanogens on nets and retreats which while initially collected passively, reflect patterns of microbial growth and not microbial patterns found in streams.

Additional Information

Language: English
Date: 2015
Hydropsychid, Methane, Methane oxidizing bacteria, Methanogen, Retreats, Stream
Hydropsychidae $x Ecophysiology

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