Food source diversity, trophic plasticity, and omnivory enhance the stability of a shallow benthic food web from a high-Arctic fjord exposed to freshwater inputs

• Published in: Limnology and Oceanography
• Main Authors: Bridier, Guillaume, Olivier, Frédéric, Chauvaud, Laurent, Sejr, Mikael K., Grall, Jacques
• Other Authors: Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU), Aarhus University Aarhus, Arctic Research Centre Aarhus (ARC), Department of Bioscience Aarhus, Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), This work was a part of the PhD project of Guillaume Bridier and co-funded by the “Allocation de Recherche Doctorale” from the Brittany Regional Council and the Université de Bretagne Occidentale/LIA BeBEST. Additional funding was provided by the Institut Polaire Français Paul-Emile Victor (IPEV – PRIVARC project), the European H2020 INTAROS program, the Agence Nationale de la Recherche (ANR GAAP), the Fondation UBO (FAC 2018) and the Observatoire Marin de l'IUEM (UMS3113)., ANR-15-ASTR-0025,GAAP,Glace Arctique par Acoustique Passive(2015), European Project: 727890,INTAROS
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: ACL; DISCOVERY; BeBest; CNRS; UBO; GAAP_ANR-15-ASTR-0025; UE project INTAROS; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; Arctic; Greenland; Climate change
• Online Access: https://hal.archives-ouvertes.fr/hal-03246773; https://doi.org/10.1002/lno.11688

WOS:000612491200001 International audience Under climate change, many Arctic coastal ecosystems receive increasing amounts of freshwater, with ecological consequences that remain poorly understood. In this study, we investigated how freshwater inputs may affect the small-scale structure of benthic food webs in a low-production high-Arctic fjord (Young Sound, NE Greenland). We seasonally sampled benthic invertebrates from two stations receiving contrasting freshwater inputs: an inner station exposed to turbid and nutrient-depleted freshwater flows and an outer station exposed to lower terrestrial influences. Benthic food web structure was described using a stable isotope approach (delta C-13 and delta N-15), Bayesian models, and community-wide metrics. The results revealed the spatially and temporally homogeneous structure of the benthic food web, characterized by high trophic diversity (i.e., a wide community isotopic niche). Such temporal stability and spatial homogeneity mirrors the high degree of trophic plasticity and omnivory of benthic consumers that allows the maintenance of several carbon pathways through the food web despite different food availability. Furthermore, potential large inputs of shelf organic matter together with local benthic primary production (i.e., macroalgae and presumably microphytobenthos) may considerably increase the stability of the benthic food web by providing alternative food sources to locally runoff-impacted pelagic primary production. Future studies should assess beyond which threshold limit a larger increase in freshwater inputs might cancel out these stability factors and lead to marked changes in Arctic benthic ecosystems.