Sea otter population status and the process of recovery from the 1989 'Exxon Valdez' oil spill

Bodkin, James L.; Ballachey, Brenda E.; Dean, Thomas A.; Fukuyama, Allan K.; Jewett, Stephen C.; McDonald, Lyman L.; Monson, Daniel H.; O'Clair, Charles E.; VanBlaricom, Glenn R.

doi:10.3354/meps241237

Cited by 100 publications

(117 citation statements)

References 127 publications

(91 reference statements)

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“…where assimilated doses to the mostexposed 4% of the population would exceed effects thresholds. That quantile matches the rationale of Bodkin et al (2002) (that the overall western PWS population increased at a rate of ~0.04 yr −1 while the NKI subpopulation remained constant over an 8 yr period [1993 to 2001] at ~75 individuals) in concluding that the NKI subpopulation of sea otters continued to experience effects. That rate translates into a net absence of ~3 additional sea otters per year at NKI if that subpopulation were growing at the same rate as the total PWS population.…”

Section: Risks To Sea Ottersmentioning

confidence: 73%

Quantifying long-term risks to sea otters from the 1989 ‘Exxon Valdez’ oil spill: Comment on Bodkin et al. (2012)

Harwell¹,

Gentile²

2013

Mar. Ecol. Prog. Ser.

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Bodkin et al. (2012; Mar Ecol Prog Ser 447:273−287) assessed the frequency at which sea otters Enhydra lutris might encounter subsurface oil residues from the 'Exxon Valdez' oil spill. They concluded that a pathway exists for exposures of sea otters to residual oil in the intertidal zone, and imply that this pathway has delayed recovery of sea otters. We agree that the potential exposure pathway exists, and the Bodkin et al. (2012) estimates of the frequency of encountering subsurface oil residues (4 to 10 times per year) comport with our previously published studies (2 to 7 times per year). However, we disagree that this pathway constitutes a significant risk to sea otters. We discuss results from our quantitative ecological risk assessment using an individualbased model that specifically simulated this pathway of exposures to a population of 500 000 sea otters. This conservative model predicted that assimilated doses of polycyclic aromatic hydrocarbons in subsurface oil residues to the 1-in-1000 th most-exposed sea otters would be 1 to 2 orders of magnitude below the chronic effects thresholds that we established using USEPA data and methodology. When we artificially increased the rate of encountering subsurface oil residues, it required 4 to 10 encounters per day to reach effects levels. We conclude that the subsurface oil residues from the oil spill could not plausibly be responsible for any individual-or populationlevel effect on the sea otters at northern Knight Island.

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Section: Risks To Sea Ottersmentioning

confidence: 73%

Quantifying long-term risks to sea otters from the 1989 ‘Exxon Valdez’ oil spill: Comment on Bodkin et al. (2012)

Harwell¹,

Gentile²

2013

Mar. Ecol. Prog. Ser.

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“…For example, sea otter (Enhydra lutris) numbers in heavily oiled regions of Prince William Sound were well below estimates of prespill numbers [1]. Also, sea otter survival in oiled areas was depressed through at least 1998 [39].…”

Section: Discussionmentioning

confidence: 98%

“…One of the more remarkable and unanticipated findings from this body of work was the length of time (at least a decade) over which animals were exposed to residual oil and showed depression of various population demographic attributes [1][2][3]. Peterson et al [3] considered these results to represent a paradigm shift in the way in which oil contamination is thought to affect the environment; in particular, chronic, delayed, and indirect effects of oil spills appear to have much longer and larger consequences on wildlife populations and communities than previously assumed.…”

Section: Introductionmentioning

confidence: 99%

Cytochrome P4501A biomarker indication of oil exposure in harlequin ducks up to 20 years after the Exxon Valdez oil spill

Esler

Trust

Ballachey

et al. 2010

Enviro Toxic and Chemistry

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Abstract-Hydrocarbon-inducible cytochrome P4501A (CYP1A) expression was measured, as ethoxyresorufin-O-deethylase (EROD) activity, in livers of wintering harlequin ducks (Histrionicus histrionicus) captured in areas of Prince William Sound, Alaska, USA, oiled by the 1989 Exxon Valdez spill and in birds from nearby unoiled areas, during 2005 to 2009 (up to 20 years following the spill). The present work repeated studies conducted in 1998 that demonstrated that in harlequin ducks using areas that received Exxon Valdez oil, EROD activity was elevated nearly a decade after the spill. The present findings strongly supported the conclusion that average levels of hepatic EROD activity were higher in ducks from oiled areas than those from unoiled areas during 2005 to 2009. This result was consistent across four sampling periods; furthermore, results generated from two independent laboratories using paired liver samples from one of the sampling periods were similar. The EROD activity did not vary in relation to age, sex, or body mass of individuals, nor did it vary strongly by season in birds collected early and late in the winter of 2006 to 2007, indicating that these factors did not confound inferences about observed differences between oiled and unoiled areas. We interpret these results to indicate that harlequin ducks continued to be exposed to residual Exxon Valdez oil up to 20 years after the original spill. This adds to a growing body of literature suggesting that oil spills have the potential to affect wildlife for much longer time frames than previously assumed. Environ. Toxicol.

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“…A study published in January 8 found that oil from the spill persists today in anoxic layers of soil on nearby beaches. Animals such as sea ducks and otters in the affected areas showed boosted levels of liver enzymes, a marker for hydrocarbons, for at least a decade afterwards 9,10 .…”

Section: Probing the Wetlandsmentioning

confidence: 99%

Deepwater Horizon: After the oil

Mascarelli¹

2010

Nature

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Sea otter population status and the process of recovery from the 1989 'Exxon Valdez' oil spill

Cited by 100 publications

References 127 publications

Quantifying long-term risks to sea otters from the 1989 ‘Exxon Valdez’ oil spill: Comment on Bodkin et al. (2012)

Quantifying long-term risks to sea otters from the 1989 ‘Exxon Valdez’ oil spill: Comment on Bodkin et al. (2012)

Cytochrome P4501A biomarker indication of oil exposure in harlequin ducks up to 20 years after the Exxon Valdez oil spill

Deepwater Horizon: After the oil

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