Using Demographic Analyses to Evaluate the Impact of Man-made Disasters on Imperiled Species: Piping Plovers and the Deepwater Horizon Oil Spill

Even in the presence of environmental safeguards,
catastrophic accidents related to anthropogenic activities occur that can result
in both immediate and chronic impacts on local biota. However, due to the
unplanned nature of catastrophes, studies aimed to identify the effects of
these accidents on an ecosystem and its inhabitants often have imperfect study
designs that are reactive rather than proactive, resulting in methodological
and analytical challenges. On 20 April 2010, following an explosion on the Deepwater
Horizon, a well blowout occurred on the seafloor approximately 80 km off the
Louisiana coast in the Gulf of Mexico. This blowout resulted in the largest
marine oil spill in United States history, which impacted critical migratory
stopover and overwintering habitat for many seabird and shorebird species,
including species of high conservation concern such as the piping plover (Charadrius melodus). Here, we assessed
the potential short-term and carry-over demographic impacts of the Deepwater
Horizon oil spill on piping plovers in a capture-mark-recapture framework. We
examined whether a series of demographic processes, including probabilities of
remaining at a specific wintering site, over-winter and annual apparent
survival, winter stopover duration, and abundance varied among oiled and
unoiled habitats. We found that the perceived amount of oiling on land, in
water, and on individual birds, as well as numerous demographic processes, were
spatially or temporally variable. However, we found no support that piping
plover demography was negatively influenced by the magnitude of oil observed at
an impacted area, or that demographic rates substantially varied between reference
and oil impacted areas. Nor did we find that piping plovers that were observed
to be oiled had lower survival probabilities following the DWH oil spill
relative to non-oiled individuals from the same winter population. Although we
did not find that the Deepwater Horizon oil spill substantially influenced piping
plovers, our methods provide an analytical framework to more appropriately
address both the short or long-term impacts of an anthropogenic disturbance on
a species.
Data from:
Gibson, D., D.H. Catlin, K.L.
Hunt, J. D. Fraser, S. Karpanty, M.J. Friedrich,  M.K. Bimbi, J. B. Cohen, and S.B. Maddock (in
review). Using Demographic Analyses to Evaluate the Impact of Man-made
Disasters on Imperiled Species: Piping Plovers and the Deepwater Horizon Oil
Spill