title: Meiofauna increases bacterial denitrification in marine sediments.
abstract: Denitrification is a critical process that can alleviate the effects of excessive nitrogen availability in aquatic ecosystems subject to eutrophication. An important part of denitrification occurs in benthic systems where bioturbation by meiofauna (invertebrates <1 mm) and its effect on element cycling are still not well understood. Here we study the quantitative impact of meiofauna populations of different abundance and diversity, in the presence and absence of macrofauna, on nitrate reduction, carbon mineralization and methane fluxes. In sediments with abundant and diverse meiofauna, denitrification is double that in sediments with low meiofauna, suggesting that meiofauna bioturbation has a stimulating effect on nitrifying and denitrifying bacteria. However, high meiofauna densities in the presence of bivalves do not stimulate denitrification, while dissimilatory nitrate reduction to ammonium rate and methane efflux are significantly enhanced. We demonstrate that the ecological interactions between meio-, macrofauna and bacteria are important in regulating nitrogen cycling in soft-sediment ecosystems.
authors.affiliation: Department of Geological Sciences, Stockholm University, 106 91 Stockholm, Sweden.
authors.forename: S
authors.initials: S
authors.lastname: Bonaglia
authors.affiliation: Department of Ecology, Environment and Plant Sciences, Stockholm University, 106 91 Stockholm, Sweden.
authors.forename: F J A
authors.initials: FJ
authors.lastname: Nascimento
authors.affiliation: Department of Life Sciences, University of Parma, 43124 Parma, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Bartoli
authors.affiliation: Department of Ecology, Environment and Plant Sciences, Stockholm University, 106 91 Stockholm, Sweden.
authors.forename: I
authors.initials: I
authors.lastname: Klawonn
authors.affiliation: Department of Geological Sciences, Stockholm University, 106 91 Stockholm, Sweden.
authors.forename: V
authors.initials: V
authors.lastname: Brüchert
mesh_terms: D064751:Ammonium Compounds / Q000737:chemistry; D000818:Animals; D059001:Aquatic Organisms; D001419:Bacteria / Q000378:metabolism; D018533:Biomass; D049872:Bivalvia; D058440:Denitrification; D004058:Diffusion; D017753:Ecosystem; D005068:Eutrophication; D019015:Geologic Sediments / Q000382:microbiology*; D008697:Methane / Q000737:chemistry; D009348:Nematoda; D009566:Nitrates / Q000737:chemistry; D009584:Nitrogen / Q000737:chemistry; D058458:Nitrogen Cycle; D010100:Oxygen / Q000737:chemistry; D016062:Porosity; D013696:Temperature
chemical_list: D064751:Ammonium Compounds; D009566:Nitrates; D009584:Nitrogen; D008697:Methane; D010100:Oxygen