MEPS 567:157-172 (2017)  -  DOI:

Dietary plasticity in the bivalve Astarte moerchi revealed by a multimarker study in two Arctic fjords

Silvia De Cesare1, Tarik Meziane1,*, Laurent Chauvaud2, Joëlle Richard2,6, Mikael K. Sejr3,4, Julien Thébault2, Gesche Winkler5, Frédéric Olivier1

1Unité Mixte de Recherche Biologie des organismes et écosystèmes aquatiques (BOREA UMR 7208), Sorbonne Université, Muséum National d’Histoire Naturelle, Université Pierre et Marie Curie, Institut de Recherche pour le Développement, Université de Caen-Normandie, Université des Antilles, 75005 Paris, France
2Institut Universitaire Européen de la Mer, Unité Mixte de Recherche Laboratoire des sciences de l’environnement marin (LEMAR, UMR 6539), Centre National de la Recherche Scientifique, Institut de Recherche pour le Développement, Université de Bretagne Occidentale, Technopôle Brest-Iroise, 29280 Plouzané, France
3Arctic Research Centre, Aarhus University, Ny Munkegade bldg. 1540, 8000 Aarhus C, Denmark
4Department of BioScience, Aarhus University, Vejlsøvej 25, 8600 Silkeborg, Denmark
5Institut des Sciences de la Mer (ISMER), Université du Québec à Rimouski (UQAR), Rimouski, QC G5L 3A1, Canada
6Present address: Coastal Watershed Institute, Florida Gulf Coast University, Fort Myers, FL 33965, USA
*Corresponding author:

ABSTRACT: Arctic coastal ecosystems are likely to be strongly affected by predicted environmental changes such as sea-ice decline and increase in freshwater input and turbidity. These changes are expected to impact primary production dynamics and consequently benthic consumers. The trophic relationship between primary producers and benthic primary consumers were compared in 2 Arctic fjords with different seasonal ice-cover: Young Sound (NE Greenland, a high-Arctic fjord) and Kongsfjorden (Svalbard Archipelago, a sub-Arctic fjord). For comparison, we selected the filter-feeding bivalve Astarte moerchi (belonging to the complex A. borealis), which has a broad geographical distribution in the Arctic. The bivalve digestive glands and food sources were characterized with fatty acids (FAs), bulk stable isotopes, and compound-specific stable isotopes of individual FAs. Our results suggest that diatoms of pelagic and/or benthic origin are the main contributors to the A. moerchi diet in Young Sound and make up a less important fraction of the diet in the Kongsfjorden population. A contribution by sympagic diatoms is clearly excluded in the sub-Arctic fjord and needs to be further assessed in the Arctic fjord. The A. moerchi diet in sub-Arctic Kongsfjorden is more diversified, varies with season, and has contributions from dinoflagellates and macroalgal detritus. These results, together with higher concentrations of total FAs in the Young Sound population, demonstrated and characterized the trophic plasticity of this bivalve species. Based on these results, we discuss potential effects of environmental factors (shifts in trophic resources, increase in turbidity) for A. moerchi populations in changing Arctic ecosystems.

KEY WORDS: Arctic benthos · Climate change · Pelagic-benthic coupling · Filter-feeding bivalves · Fatty acids · Trophic markers · Compound-specific carbon stable isotopes

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Cite this article as: De Cesare S, Meziane T, Chauvaud L, Richard J and others (2017) Dietary plasticity in the bivalve Astarte moerchi revealed by a multimarker study in two Arctic fjords. Mar Ecol Prog Ser 567:157-172.

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