Intense photooxidative degradation of planktonic and bacterial lipids in sinking particles collected with sediment traps across the Canadian Beaufort Shelf (Arctic Ocean)

• Published in: Biogeosciences
• Main Authors: Rontani, J.-F., Charrière, B., Forest, A., Heussner, S., Vaultier, F., Petit, Morgan, Delsaut, N., Fortier, L., Sempere, Richard
• 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), Centre de Formation et de Recherche sur les Environnements Méditérranéens (CEFREM), Université de Perpignan Via Domitia (UPVD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Laval Québec (ULaval), ANR-08-BLAN-0308,Malina,How changes in ice cover, permafrost and UV radiation impact on biodiversity and biogeochemical fluxes in the Arctic Ocean(2008)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2012
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Arctic; Arctic Ocean; Copepods; midnight sun
• Online Access: https://amu.hal.science/hal-02051678; https://amu.hal.science/hal-02051678/document; https://amu.hal.science/hal-02051678/file/bg-9-4787-2012.pdf; https://doi.org/10.5194/bg-9-4787-2012

International audience The lipid content of seven samples of sinking particles collected with sediment traps moored at ∼ 100 m depth in summer and fall across the Canadian Beaufort Shelf (Arc-tic Ocean) was investigated. Our main goal was to quantify and characterize the biotic and abiotic degradation processes that acted on sinking material during these periods. Diatoms, which dominated the phytoplanktonic assemblage in every trap sample, appeared to be remarkably sensitive to Type II (i.e. involving singlet oxygen) photodegradation processes in summer, but seemed to be relatively unaffected by biotic degradation at the same time. Hence, the relative recalcitrance of phytodetritus towards biodegradation processes during the Arctic midnight sun period was attributed to the strong photodegradation state of heterotrophic bacteria , which likely resulted from the efficient transfer of singlet oxygen from photodegraded phytoplanktonic cells to attached bacteria. In addition, the detection in trap samples of photoproducts specific to wax ester components found in her-bivorous copepods demonstrated that zooplanktonic faecal material exported out of the euphotic zone in summer were affected by Type II photodegradation processes as well. By contrast, sinking particles collected during the autumn were not influenced by any light-driven stress. Further chemical analyses showed that photodegraded sinking particles contained an important amount of intact hydroperoxides, which could then induce a strong oxidative stress in underlying sediments .