Spatial variability in total and organic mercury levels in Antarctic krill Euphausia superba across the Scotia Sea

• Published in: Environmental Pollution
• Main Authors: Seco, José, Xavier, José, Coelho, Joao, Pereira, Bárbara, Tarling, Geraint, Pardal, Miguel, Bustamante, Paco, Stowasser, Gabriele, Brierley, Andrew, Pereira, Maria
• Other Authors: CESAM & Department of Chemistry, Universidade de Aveiro, Marine and Environmental Sciences Centre (MARE UC), Universidade de Coimbra Coimbra, British Antarctic Survey (BAS), Natural Environment Research Council (NERC), CESAM and Department of Biology, University of Minho Braga, Centre for Functional ecology, University of Coimbra Portugal (UC), LIttoral ENvironnement et Sociétés - UMR 7266 (LIENSs), Institut national des sciences de l'Univers (INSU - CNRS)-La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Scottish Oceans Institute, University of St Andrews Scotland
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2019
• Subjects: Food-web; Eggs; Organic Mercury; Southern Ocean; Antarctica; [SDV.TOX.ECO]Life Sciences [q-bio]/Toxicology/Ecotoxicology; Antarctic; Scotia Sea; South Orkney Islands; The Antarctic; Antarc*; Antarctic Krill; Euphausia superba
• Online Access: https://hal.science/hal-02339684; https://hal.science/hal-02339684/document; https://hal.science/hal-02339684/file/Seco%20et%20al%202019%20ENPO.pdf; https://doi.org/10.1016/j.envpol.2019.01.031

International audience Total and organic mercury concentrations were determined for males, females and juveniles of Euphausia superba collected at three discrete locations in the Scotia Sea (the South Orkney Islands, South Georgia and the Antarctic Polar Front) to assess spatial mercury variability in Antarctic krill. There was clear geographic differentiation in mercury concentrations, with specimens from the South Orkneys having total mercury concentrations 5 to 7 times higher than Antarctic krill from South Georgia and the Antarctic Polar Front. Mercury did not appear to accumulate with life-stage since juveniles had higher concentrations of total mercury (0.071 µg g-1 from South Orkney Islands; 0.015 µg g-1 from South Georgia) than adults (0.054 µg g-1 in females and 0.048 µg g-1 in males from South Orkney Islands; 0.006 µg g-1 in females and 0.007 µg g-1 in males from South Georgia). Results suggest that females use egg laying as a mechanism to excrete mercury, with eggs having higher concentrations than the corresponding somatic tissue. Organic mercury makes up a minor percentage of total mercury (15 to 37%) with the percentage being greater in adults than in juveniles. When compared to euphausiids from other parts of the world, the concentration of mercury in Antarctic krill is within the same range, or higher, highlighting the global distribution of this contaminant. Given the high potential for biomagnification of mercury through food webs, concentrations in Antarctic krill may have deleterious effects on long-lived Antarctic krill predators.