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Marine Ecology Progress Series

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MEPS 615:31-49 (2019)  -  DOI:

Food sources of macrozoobenthos in an Arctic kelp belt: trophic relationships revealed by stable isotope and fatty acid analyses

M. Paar1,5,*, B. Lebreton2, M. Graeve3, M. Greenacre4, R. Asmus1, H. Asmus1

1Wattenmeerstation Sylt, Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Hafenstraße 43, 25992 List/Sylt, Germany
2UMR 7266 Littoral, Environment and Societies, Institut du littoral et de l’environnement, CNRS-University of La Rochelle, 2 rue Olympes de Gouges, 17000 La Rochelle, France
3Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Am Handelshafen 12, 27570 Bremerhaven, Germany
4Department of Economics and Business, Universitat Pompeu Fabra and Barcelona Graduate School of Economics, Ramon Trias Fargas, 25-27, 08005 Barcelona, Spain
5Present address: Biologische Station Hiddensee, University Greifswald, Biologenweg 15, 18565 Kloster, Germany
*Corresponding author:

ABSTRACT: Arctic kelp belts, made of large perennial macroalgae of the order Laminariales, are expanding because of rising temperatures and reduced sea ice cover of coastal waters. In summer 2013, the trophic relationships within a kelp belt food web in Kongsfjorden (Spitsbergen) were determined using fatty acid and stable isotope analyses. Low relative proportions of Phaeophyta fatty acid trophic markers (i.e. 20:4(n-6), 18:3(n-3) and 18:2(n-6)) in consumers (3.3-8.9%), as well as low 20:4(n-6)/20:5(n-3) ratios (<0.1-0.6), indicated that Phaeophyta were poorly used by macrozoobenthos as a food source, either fresh or as detritus. Relatively high δ13C values measured in macrozoobenthos (-22.5 to -16.1‰) ruled out an important role of erect Rhodophyta, which were much more 13C depleted (-37.1 to -35.8‰). Instead, δ13C values and relatively high abundances of typical diatom (14:0, 16:1(n-7), 20:5(n-3)) and flagellate (18:4(n-3), 22:6(n-3)) fatty acid trophic markers in consumers pointed out an important use of microalgae, likely of pelagic and benthic origin (i.e. senescent phytoplankton bloom, eroded epiphytes and suspended epilithic material). The use of these food resources may be fostered by their trapping under the kelp canopy.

KEY WORDS: Food web · Polar coastal ecosystem · Trophic markers · Macrofauna · Macroalgae · Detritus

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Cite this article as: Paar M, Lebreton B, Graeve M, Greenacre M, Asmus R, Asmus H (2019) Food sources of macrozoobenthos in an Arctic kelp belt: trophic relationships revealed by stable isotope and fatty acid analyses. Mar Ecol Prog Ser 615:31-49.

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