http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0096191

Peterson SH, Hassrick JL, Lafontaine A, Thomé J-P, Crocker DE, et al.
(2014) Effects of Age, Adipose Percent, and Reproduction on PCB
Concentrations and Profiles in an Extreme Fasting North Pacific Marine
Mammal. PLoS ONE 9(4): e96191. doi:10.1371/journal.pone.0096191

Abstract
Persistent organic pollutants, including polychlorinated biphenyls
(PCBs), are widely distributed and detectable far from anthropogenic
sources. Northern elephant seals (Mirounga angustirostris) biannually
travel thousands of kilometers to forage in coastal and open-ocean
regions of the northeast Pacific Ocean and then return to land where
they fast while breeding and molting. Our study examined potential
effects of age, adipose percent, and the difference between the breeding
and molting fasts on PCB concentrations and congener profiles in blubber
and serum of northern elephant seal females. Between 2005 and 2007, we
sampled blubber and blood from 58 seals before and after a foraging
trip, which were then analyzed for PCBs. Age did not significantly
affect total PCB concentrations; however, the proportion of PCB
congeners with different numbers of chlorine atoms was significantly
affected by age, especially in the outer blubber. Younger adult females
had a significantly greater proportion of low-chlorinated PCBs (tri-,
tetra-, and penta-CBs) than older females, with the opposite trend
observed for hepta-CBs, indicating that an age-associated process such
as parity (birth) may significantly affect congener profiles. The
percent of adipose tissue had a significant relationship with inner
blubber PCB concentrations, with the highest mean concentrations
observed at the end of the molting fast. These results highlight the
importance of sampling across the entire blubber layer when assessing
contaminant levels in phocid seals and taking into account the adipose
stores and reproductive status of an animal when conducting contaminant
research.

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