Mercury Accumulation in Harbour Seals from the Nor

Authors: Marie Noël Steven Jeffries Dyanna M Lambourn Kevin Telmer Robie Macdonald Peter S Ross

Publish Date: 2015/07/10

Volume: 70, Issue: 1, Pages: 56-66

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Abstract

Mercury Hg bioaccumulates in the aquatic food chain in the form of methylmercury a compound well known for its neurotoxicity We analyzed total mercury THg in hair collected from 209 harbour seals captured at 10 sites in British Columbia Canada and Washington State USA between 2003 and 2010 In addition laser ablation inductivelycoupled plasma mass spectrometry LAICPMS allowed for a highly refined analysis of THg accumulation over time by examining nine whiskers taken from 4 to 6weekold pups We estimate that THg concentrations in pups increased sharply at a point corresponding to mid to late gestation of their time in utero 47 ± 08 and 66 ± 13 µg/g dry weight dw respectively and then again at the onset of nursing 81 ± 13 µg/g dw These abrupt changes highlight the importance of both pre and postnatal THg transfer from the mother to the growing fetus and the newborn pup While THg levels varied among sites hair analyses from seals collected at the same site demonstrated the influence of age in THg accumulation with pups 53 ± 03 µg/g and juveniles 45 ± 05 µg/g having lower levels than those in adults 83 ± 08 µg/g Our results revealed that 33  of the pups sampled n = 167 had THg levels that surpassed a mammalian hair threshold for neurochemical alterations This study suggests that Hg could represent a health concern to marine wildlife especially as atmospheric emissions of this toxic element from human activities in the Pacific Rim and worldwide continueThe authors thank Neil Dangerfield Monique Lance Bryan Murphie Joe Evanson and many others for field support in British Columbia and Washington State as well as Jody Spence Ricardo Rossin and Paul Eby for help with mercury and stable isotope analyses and data interpretation This study was supported in part through grants from Fisheries and Oceans Canada Health Canada National First Nations Environmental Contaminants Program the US Environmental Protection Agency and the National Oceanic and Atmospheric Administration

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