Quantitative Assessment of Current Risks to Harlequin Ducks in Prince William Sound, Alaska, from the Exxon Valdez Oil Spill
Authored by Mark A Harwell, John H Gentile, Keith R Parker, Stephen M Murphy, Robert H Day, A Edward Bence, Jerry M Neff, John A Wiens
Date Published: 2012
DOI: 10.1080/10807039.2012.650582
Sponsors:
ExxonMobil Corporation
Platforms:
STELLA
Model Documentation:
Other Narrative
Flow charts
Mathematical description
Model Code URLs:
Model code not found
Abstract
Harlequin Ducks (Histrionicus histrionicus) were adversely affected by
the Exxon Valdez oil spill (EVOS) in Prince William Sound (PWS), Alaska, and some have suggested effects continue two decades later. We present
an ecological risk assessment evaluating quantitatively whether PWS
seaducks continue to be at-risk from polycyclic aromatic hydrocarbons
(PAHs) in residual Exxon Valdez oil. Potential pathways for PAH
exposures are identified for initially oiled and never-oiled reference
sites. Some potential pathways are implausible (e. g., a seaduck
excavating subsurface oil residues), whereas other pathways warrant
quantification. We used data on PAH concentrations in PWS prey species, sediments, and seawater collected during 2001-2008 to develop a
stochastic individual-based model projecting assimilated doses to
seaducks. We simulated exposures to 500,000 individuals in each of eight
age/gender classes, capturing the variability within a population of
seaducks living in PWS. Doses to the maximum-exposed individuals are
similar to 400-4,000 times lower than chronic toxicity reference values
established using USEPA protocols for seaducks. These exposures are so
low that no individual-level effects are plausible, even within a
simulated population that is orders-of-magnitude larger than exists in
PWS. We conclude that toxicological risks to PWS seaducks from residual
Exxon Valdez oil two decades later are essentially non-existent.
Tags
Body-mass
Polycyclic aromatic-hydrocarbons
Louisiana crude-oil
Photostimulated
mallard ducks
Glaucous-winged gulls
Base-line conditions
Anas-platyrhynchos
Ingested petroleum
Sea otter
Environmental
accidents