Control of the preservation of sympagic algal material in surficial sediments of central and eastern Baffin Bay by bactericidal hydroperoxides and free fatty acids

• Published in: Marine Chemistry
• Main Authors: Rontani, Jean, François, Lalande, Catherine, Vilgrain, Laure, Vaultier, Frédéric, Amiraux, Rémi
• Other Authors: Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Takuvik Joint International Laboratory ULAVAL-CNRS, Université Laval Québec (ULaval)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'océanographie de Villefranche (LOV), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), 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)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2022
• Subjects: Central and Eastern Baffin Bay; Surficial sediments; Sinking particles; Sympagic algae preservation; MUFA oxidation products; Bacteria oxidation; [CHIM.ANAL]Chemical Sciences/Analytical chemistry; [CHIM.OTHE]Chemical Sciences/Other; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; Baffin Bay; Baffin; ice algae
• Online Access: https://hal.science/hal-03833544; https://hal.science/hal-03833544/document; https://hal.science/hal-03833544/file/MARCHE-D-22-00075.pdf; https://doi.org/10.1016/j.marchem.2022.104177

International audience Monounsaturated fatty acids and their oxidation products were quantified in surficial sediments (0–1 cm) dominated by sympagic (ice-associated) material released at the end of the ice melt collected in summer in central and eastern Baffin Bay during the 2016 GreenEdge campaign. Sympagic algae preservation towards bacterial mineralization was monitored based on intact and oxidized C16:1ω7 (palmitoleic) acid, and oxidation products of C18:1ω7 (vaccenic) and C16:1ω5 acids provided insights on the photooxidative and autoxidative alterations of bacteria present in these sediment samples. Preservation of sympagic algal material appeared to be highest at the stations that were relatively unaffected by copepod grazing and that contained strongly autoxidized (and thus inactive) bacteria. Analysis of sinking particles collected with a drifting trap showed an intense flux of highly photooxidized ice algae in early July that was dominated by Navicula spp. and associated with bacteria that had also been strongly altered by photooxidative processes. It is proposed that subsequent homolytic decomposition of the hydroperoxides resulting from this intense photooxidation may have driven the strong autoxidation of sympagic algae and bacteria observed in the sediments. The lack of colonization of sympagic material by active benthic bacteria observed at some of the stations investigated was attributed to its high content in deleterious autoxidative hydroperoxides and free fatty acids (reaching for example 107% and 22% of residual palmitoleic acid, respectively, at station 605)