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Marine Ecology Progress Series

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MEPS 629:19-42 (2019)  -  DOI:

Chemosynthesis influences food web and community structure in high-Arctic benthos

Emmelie K. L. Åström1,2,*, Michael L. Carroll1,3, Arunima Sen1,9, Helge Niemann1,4,5,6, William G. Ambrose Jr.3,7, Moritz F. Lehmann4, JoLynn Carroll3,8

1CAGE-Centre for Arctic Gas hydrate, Environment and Climate, Department of Geosciences, UiT-The Arctic University of Norway, 9037 Tromsø, Norway
2Department of Arctic and Marine Biology, UiT-The Arctic University of Norway, 9037 Tromsø, Norway
3Akvaplan-niva, FRAM-High North Research Centre for Climate and the Environment, 9296 Tromsø, Norway
4Department of Environmental Sciences, University of Basel, Basel 4056, Switzerland
5NIOZ-Royal Netherlands Institute for Sea Research, Department of Marine Microbiology and Biogeochemistry, and Utrecht University, 1790 AB Den Burg, Texel, The Netherlands
6Department of Earth Sciences, Faculty of Geosciences, Utrecht University, 3508 TC Utrecht, the Netherlands
7School of the Coastal Environment, Coastal Carolina University, Conway, South Carolina 29528, USA
8Department of Geosciences, UiT-The Arctic University of Norway, 9037 Tromsø, Norway
9Present address: Faculty of Bioscience and Aquaculture, Nord University, 8049 Bodø, Norway
*Corresponding author:

ABSTRACT: Cold seeps are locations where seafloor communities are influenced by the seepage of methane and other reduced compounds from the seabed. We examined macro-infaunal benthos through community analysis and trophic structure using stable isotope analysis at 3 seep locations in the Barents Sea. These seeps were characterized by high densities of the chemosymbiotic polychaetes Siboglinidae, clade Frenulata (up to 32120 ind. m-2), and thyasirid bivalves, Mendicula cf. pygmaea (up to 4770 ind. m-2). We detected low δ13C signatures in chemosymbiotic polychaetes and in 3 species of omnivorous/predatory polychaetes. These δ13C signatures indicate the input of chemosynthesis-based carbon (CBC) into the food web. Applying a 2-source mixing model, we demonstrated that 28-41% of the nutrition of non-chemosymbiotic polychaetes originates from CBC. We also documented large community variations and small-scale variability within and among the investigated seeps, showing that the impact of seepage on faunal community structure transcends geographic boundaries within the Barents Sea. Moreover, aggregations of heterotrophic macro- and megafauna associated with characteristic seep features (microbial mats, carbonate outcrops, and chemosymbiotic worm-tufts) add 3-dimensional structure and habitat complexity to the seafloor. Cold seeps contribute to the hydrocarbon-derived chemoautotrophy component of these ecosystems and to habitat complexity. These characteristics make the cold seeps of potential high ecological relevance in the functioning of the larger Arctic-Barents Sea ecosystem.

KEY WORDS: Cold seeps · Benthos · Methane · Trophic structure · Stable isotopes · Barents Sea · Svalbard

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Cite this article as: Åström EKL, Carroll ML, Sen A, Niemann H, Ambrose WG Jr, Lehmann MF, Carroll J (2019) Chemosynthesis influences food web and community structure in high-Arctic benthos. Mar Ecol Prog Ser 629:19-42.

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