title: Deep-ocean foraging northern elephant seals bioaccumulate persistent organic pollutants.
abstract: As top predators in the northeast Pacific Ocean, northern elephant seals (Mirounga angustirostris) are vulnerable to bioaccumulation of persistent organic pollutants (POPs). Our study examined a suite of POPs in blubber (inner and outer) and blood (serum) of free-ranging northern elephant seals. For adult females (N=24), we satellite tracked and sampled the same seals before and after their approximately seven month long foraging trip. For males, we sampled different adults and sub-adults before (N=14) and after (N=15) the same foraging trip. For females, we calculated blubber burdens for all compounds. The highest POP concentrations in males and females were found for ∑DDTs and ∑PCBs. In blubber and serum, males had significantly greater concentrations than females for almost all compounds. For males and females, ∑DDT and ∑PBDEs were highly correlated in blubber and serum. While ∑PCBs were highly correlated with ∑DDTs and ∑PBDEs in blubber and serum for males, ∑PCBs showed weaker correlations with both compounds in females. As females gained mass while foraging, concentrations of nearly all POPs in inner and outer blubber significantly decreased; however, the absolute burden in blubber significantly increased, indicating ingestion of contaminants while foraging. Additionally, we identified three clusters of seal foraging behavior, based on geography, diving behavior, and stable carbon and nitrogen isotopes, which corresponded with differences in ∑DDTs, ∑PBDEs, MeO-BDE 47, as well as the ratio of ∑DDTs to ∑PCBs, indicating the potential for behavior to heighten or mitigate contaminant exposure. The greatest concentrations of ∑DDTs and ∑PBDEs were observed in the cluster that foraged closer to the coast and had blood samples more enriched in (13)C. Bioaccumulation of POPs by elephant seals supports mesopelagic food webs as a sink for POPs and highlights elephant seals as a potential sentinel of contamination in deep ocean food webs.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, 100 Shaffer Road, Santa Cruz, CA 95060, USA. Electronic address: sarahpeterson23@gmail.com.
authors.forename: Sarah H
authors.initials: SH
authors.lastname: Peterson
authors.affiliation: Department of Environmental Science, Policy and Management, University of California, Berkeley, 130 Mulford Hall, Berkeley, CA 94720, USA.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Peterson
authors.affiliation: Institut des Sciences de la Vie, Université catholique de Louvain, Croix du Sud 2/L7.05.08, 1348 Louvain-la-Neuve, Belgium.
authors.forename: Cathy
authors.initials: C
authors.lastname: Debier
authors.affiliation: Toxicological Center, Campus Drie Eiken, Universiteit Antwerpen, Universiteitsplein 1, 2610 Wilrijk, Belgium.
authors.forename: Adrian
authors.initials: A
authors.lastname: Covaci
authors.affiliation: Toxicological Center, Campus Drie Eiken, Universiteit Antwerpen, Universiteitsplein 1, 2610 Wilrijk, Belgium; Department of Chemistry, "Al. I. Cuza" University of Iasi, 700506 Iasi, Romania.
authors.forename: Alin C
authors.initials: AC
authors.lastname: Dirtu
authors.affiliation: Toxicological Center, Campus Drie Eiken, Universiteit Antwerpen, Universiteitsplein 1, 2610 Wilrijk, Belgium.
authors.forename: Govindan
authors.initials: G
authors.lastname: Malarvannan
authors.affiliation: Department of Biology, Sonoma State University, 1801 East Cotati Ave, Rohnert Park, CA 94928, USA.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Crocker
authors.affiliation: Institute of Marine Sciences, University of California, Santa Cruz, 100 Shaffer Road, Santa Cruz, CA 95060, USA.
authors.forename: Lisa K
authors.initials: LK
authors.lastname: Schwarz
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, 100 Shaffer Road, Santa Cruz, CA 95060, USA.
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Costa
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D004784:Environmental Monitoring; D005260:Female; D020387:Food Chain; D055768:Halogenated Diphenyl Ethers / Q000378:metabolism; D015386:Hazardous Substances / Q000378:metabolism; D008297:Male; D010140:Pacific Ocean; D011078:Polychlorinated Biphenyls / Q000378:metabolism; D046048:Seals, Earless / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D055768:Halogenated Diphenyl Ethers; D015386:Hazardous Substances; D014874:Water Pollutants, Chemical; D011078:Polychlorinated Biphenyls
keywords: Blubber burden; Contaminants; Ecotoxicology; Foraging ecology; Mesopelagic; Pinniped