Climate change and diminishing seasonality in Arctic benthic processes

• Published in: Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
• Main Authors: Morata, Nathalie, Michaud, Emma, Poullaouec, Marie-Aude, Devesa, Jérémy, Le Goff, Manon, Corvaisier, Rudolph, Renaud, Paul
• 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 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)-Centre National de la Recherche Scientifique (CNRS), Akvaplan-Niva Tromsø, Norwegian Institute for Water Research (NIVA), Centre National de la Recherche Scientifique (CNRS), The University Centre in Svalbard (UNIS), This study is a contribution to the projects ARCEx (NRC 228107), Marine Night (NRC 226417),WINBA (Arctic Field Grant), ESCOFAR (CNRS-EC2CO-DRIL and BIOHEFECT), IPEV (project no. 1132) and ECOTAB (ANR-11-PDOC-0018)., ANR-11-PDOC-0018,ECOTAB,Effet des changements climatiques sur le benthos en Arctique(2011)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2020
• Subjects: bioturbation; Kongsfjorden; nutrient fluxes; phytodetritus; respiration; Svalbard; [SDE.MCG]Environmental Sciences/Global Changes; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; [SDV.EE.BIO]Life Sciences [q-bio]/Ecology; environment/Bioclimatology; Arctic; Climate change; Kongsfjord*
• Online Access: https://hal.science/hal-02930802; https://hal.science/hal-02930802/document; https://hal.science/hal-02930802/file/Morataetal_PTRAS_Revised_HALVersion.pdf; https://doi.org/10.1098/rsta.2019.0369

International audience The iconic picture of Arctic marine ecosystems shows an intense pulse of biological productivity around the spring bloom that is sustained while fresh organic matter (OM) is available, after which ecosystem activity declines to basal levels in autumn and winter. We investigated seasonality in benthic biogeochemical cycling at three stations in a high Arctic fjord that has recently lost much of its seasonal ice-cover. Unlike observations from other Arctic locations, we find little seasonality in sediment community respiration and bioturbation rates, although different sediment reworking modes varied through the year. Nutrient fluxes did vary, suggesting that, although OM was processed at similar rates, seasonality in its quality led to spring/summer peaks in inorganic nitrogen and silicate fluxes. These patterns correspond to published information on seasonality in vertical flux at the stations. Largely ice-free Kongsfjorden has a considerable detrital pool in soft sediments which sustain benthic communities over the year. Sources of this include macroalgae and terrestrial runoff. Climate change leading to less ice cover, higher light availability and expanded benthic habitat may lead to more detrital carbon in the system, dampening the quantitative importance of seasonal pulses of phytodetritus to seafloor communities in some areas of the Arctic.