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Marine Ecology Progress Series

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MEPS 605:17-35 (2018)  -  DOI:

Macrobenthic community structure and influence on denitrification capacity in soft sediments (Mobile Bay, Alabama, USA)

M. P. Jacquot1,2,3, K. M. Dorgan1,4,*, B. Mortazavi1,5, A. A. Kleinhuizen1,5, W. C. Clemo1,4

1Dauphin Island Sea Lab, 101 Bienville Blvd., Dauphin Island, AL 36528, USA
2Université de Bretagne Occidentale, Laboratoire des Sciences de l’Environnement Marin (LEMAR, UMR 6539, UBO/CNRS/IRD/Ifremer), Institut Universitaire Européen de la Mer (IUEM), 29280 Plouzané, France
3Environmental and Marine Biology, Åbo Akademi University, BioCity, Artillerigatan 6, 20520 Åbo, Finland
4Department of Marine Sciences, University of South Alabama, Mobile, AL 36688, USA
5Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487, USA
*Corresponding author:

ABSTRACT: Benthic macrofauna play important roles in coastal ecosystems through their impact on nutrient cycling and by serving as an important trophic link. This study investigated the influence of environmental stressors on macrofaunal community abundance, biomass and diversity and evaluated impacts of those benthic organisms on nutrient fluxes and denitrification capacity in Mobile Bay, a shallow subtropical estuary in the northern Gulf of Mexico. Between January and May 2016, 22 stations in the lower bay were sampled, and the distance from the sea and sediment characteristics were identified as the principal constraints for macrofaunal distribution and taxonomic composition. Higher diversity of macrofauna was found near the mouth of the bay, likely due to hydrological characteristics of the bay, in addition to distance from anthropogenic disturbances near coasts. Sediments comprised of 60-80% sand showed higher abundances, biomass and diversity compared to muddier or sandier sediments, potentially because these sediments were more stable. Although macrofaunal abundance, biomass and diversity differed across stations in the bay, we did not find a relationship between macrofaunal abundances or biomass and denitrification capacity. Both abundance and biomass of infauna were low in Mobile Bay (<4000 ind. m-2 and <5 g DW m-2 at most sites) compared to those in previous studies which showed a positive relationship between macrofaunal abundances and denitrification. The lack of the relation between macrofauna and denitrification suggests that a threshold of abundance, biomass and/or burrowing activity is necessary to increase bioturbation or irrigation to sufficient levels to affect denitrification.

KEY WORDS: Benthic macrofauna · Denitrification · Nitrogen flux · Sediments · Community diversity · Environmental stressors · Mobile Bay

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Cite this article as: Jacquot MP, Dorgan KM, Mortazavi B, Kleinhuizen AA, Clemo WC (2018) Macrobenthic community structure and influence on denitrification capacity in soft sediments (Mobile Bay, Alabama, USA). Mar Ecol Prog Ser 605:17-35.

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