Benthic bioturbator enhances CH4 fluxes among aquatic compartments and atmosphere in experimental microcosms

• Published in: Canadian journal of fisheries and aquatic sciences 2009-10, Vol.66 (10), p.1649-1657
• Main Authors: Figueiredo-Barros, Marcos Paulo, Caliman, Adriano, Leal, João J. F, Bozelli, Reinaldo L, Farjalla, Vinicius F, Esteves, Francisco A
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Exploitation and management of natural biological resources (hunting, fishing and exploited populations survey, etc.); Fundamental and applied biological sciences. Psychology; General aspects; Synecology
• ISSN: 0706-652X; 1205-7533
• DOI: 10.1139/F09-111

We utilized laboratory microcosms to evaluate the effects of a benthic sediment bioturbator ( Heteromastus similis ; Polychaeta; conveyor-belt deposit feeder) on vertical distributions of CH 4 in sediment and net CH 4 fluxes across sediment-water-air interfaces. The effect of H. similis on sediment CH 4 concentration ([CH 4 ]) varied depending on sediment depth and was strongest at higher animal densities. In comparison with defaunated controls, microcosms with the highest density of H. similis exhibited an increase in [CH 4 ] of 3.7-fold, on average, at the sediment surface (0-2 cm), but these concentrations decreased by ~2-fold in deeper sediment layers (2-8 cm). However, irrespective of sediment depth, the density of H. similis resulted in an overall nonlinear reduction of bulk sediment [CH 4 ]. Most of the observed CH 4 losses from the sediment were due to CH 4 oxidation, but the bioturbatory activities of H. similis also promoted significant increases in [CH 4 ] in both the water column and the microcosm headspace. These results suggest that benthic invertebrates can mediate CH 4 turnover between compartments in aquatic ecosystems, with further consequences for the coupling between benthic-pelagic food chains via the methanotrophic-mediated microbial loop, as well as increase CH 4 emissions to the atmosphere.