Effects of the Exxon Valdez Oil Spill on Birds: Comparisons of Pre- and Post-Spill Surveys in Prince William Sound, Alaska

Abstract

We used data from pre-and post-spill surveys to assess the effects of the Exxon Valdez oil spill on the abundance and distribution of birds in Prince William Sound, Alaska. We conducted post-spill surveys during midsummer (1989-1991) in 10 bays that had been surveyed prior to the spill (1984-1985) and that had experienced different levels of initial oiling from the spill (unoiled to heavily oiled). We evaluated whether there were changes in overall abundance across all bays between the pre-spill and post-spill sampling periods, and changes in abundance in unoiled/lightly oiled bays versus moderately/heavily oiled bays that would suggest oiling impacts. Of 12 taxa examined for changes in overall abundance, 7 showed no significant change, 2 (Bald Eagle and Glaucous-winged Gull) increased in abundance, and 3 (Red-necked Grebe, Pelagic Cormorant, and Pigeon Guillemot) decreased in abundance during all three post-spill years. Of the 11 taxa examined for differences in use of oiled versus unoiled habitats, 7 showed no significant response, 1 (Black-legged Kittiwake) exhibited a positive response to oiling, and 3 (Pelagic Cormorant, Black Oystercatcher, and Pigeon Guillemot) exhibited negative responses to initial oiling. We conclude that the impacts of this oil spill on abundance and distribution of birds were most evident in 1989, the year of the spill, and were most pronounced for Pigeon Guillemots. By 1991, signs of recovery were evident for all taxa that showed initial oiling impacts.

Harlequin duck population recovery following the 'Exxon Valdez' oil spill: progress, process and constraints

“…Also, although Murphy et al (1997) had high power for detecting a 50% postspill population decline, they did not report power for detecting smaller but biologically meaningful reductions (e.g. 10%).…”

“…Because most harlequin ducks wintering in PWS breed elsewhere, results of pre-and postspill compar- Murphy et al (1997) have limited relevance for understanding dynamics of wintering populations, which we consider to be the core, demographically distinct population segments. Also, although Murphy et al (1997) had high power for detecting a 50% postspill population decline, they did not report power for detecting smaller but biologically meaningful reductions (e.g.…”

European Atlantic: the hottest oil spill hotspot worldwide

“…Oil spills can negatively influence the physiology, inmunology, and development of some organisms (Duffy et al 1994;Briggs et al 1997;Dyrynda et al 2000;Heintz et al 2000;Downs et al 2002;Rotterman and Monnett 2002), but their most evident effect is usually an important decrease or disappearance of populations of marine fauna and flora within the affected area (e.g., Frost et al 1999). The effects of crude oil on the organisms and the time needed for the recovery of ecosystems and populations are different among species, and are subject to controversy (Wiens et al 1996;Murphy et al 1997;Lance et al 2001;Esler et al 2002, Peterson et al 2003 Although the spills with the highest recognized ecological impacts were usually those in which the greatest volume of oil was spilled in the sea, a small quantity of oil spilled in pristine places can also negatively affect endangered species, as it has been reported from the Galapagos Islands after the sinking of Jessica (Wikelski et al 2002). Linked to the damage caused to the environment are the high costs to fisheries, related industries, and tourism in the affected areas.…”

Short- and long-term effects of accidental oil pollution in waters of the Nordic countries

“…An evaluation of pre-and post-spill abundances of birds in Prince William Sound indicated that three of eleven taxa evaluated had declined significantly from numbers recorded four-five years before the spill (Murphy et al 1997) 7. 7 Fish Oil spills that occur during fish spawning or when larval concentrations are high can cause egg and larval mortality, as those are both sensitive and immobile.…”