BOX 1-1 T/V Exxon Valdez, Alaska
The T/V Exxon Valdez grounded on Bligh Reef in Prince William Sound, Alaska on March, 24 1989, releasing an estimated 36,000 tonnes (10.9 million gallons) of Alaska North Slope crude oil (API [American Petroleum Institute] gravity = 29.8). Wolfe et al. (1994) estimated that, as of 1991, 41 percent of the oil stranded on intertidal habitats in Prince William Sound. About 25 percent was transported out of the sound, stranding mostly along the Kenai Peninsula, lower Cook Inlet, and the Kodiak Archipelago. More than 2,000 km of shoreline were oiled, reflecting the persistence of the spilled oil and the influence of a spring gale and a major coastal current on the transport of a large volume of oil. The extent and degree of shoreline oiling resulted in the most intensive shoreline cleanup effort ever attempted. Large volumes of water heated to 140ºF were used to flush oil from almost 30 percent of the rocky shores and gravel beaches in Prince William Sound. Despite the aggressive cleanup, oil residues persisted for more than 13 years in more sheltered habitats and porous gravel beaches. Monitoring studies have shown that intensive treatment resulted in delayed recovery of rocky shore intertidal communities (NOAA, 1997). These studies demonstrate how too-aggressive cleanup, in some instances, can slow recovery of these affected communities.
No doubt, the Exxon Valdez was a large spill that affected many valuable resources. Large numbers of animals were estimated to have been killed directly, including 900 bald eagles (Bowman, 1993), about 250,000 seabirds (Piatt and Ford, 1996), 2,800 sea otters (Garrott et al., 1993; Bodkin et al., 2001), and 300 harbor seals (Frost et al., 1994a). Both the Exxon Valdez Oil Spill Trustee Council and Exxon conducted numerous studies to assess the impacts of the spill, and Exxon paid the state and local governments $900 million for natural resource damages. Never before have so much effort and money been spent on trying to determine the extent of negative effects and the course of recovery. Yet the interpretations of the studies conducted by the trustees and Exxon varied significantly, particularly concerning sublethal and long-term impacts. There were issues with the scale and power of the studies, interpretations of uncertainty, the role of natural changes in gauging recovery, and even the source of the background hydrocarbons in Prince William Sound. The trustees’ results showed enhanced mortality to pink salmon larvae hatching in oiled gravel beds that affected their productivity and survival (Heintz et al., 1999, 2000). Exxon studies showed equal survival of eggs collected from oiled and unoiled streams (Brannon et al., 1995). Carls et al. (1999) concluded that oil exposure contributed to disease induction that caused a collapse in Pacific herring five years after the spill, although other factors could have played a role. Black oystercatchers and harlequin ducks from oiled areas of western PWS were thought to have significant declines in abundance and productivity for at least four years post-spill for oystercatchers (Klosiewski and Laing, 1994; Andres, 1997) and eight years for harlequin ducks (Esler et al., 2000c) when compared to populations from unoiled eastern PWS, although the number of breeding pairs studied was very small. However, laboratory analyses reported by Boehm et al. (1996) concluded that the body burden for individuals in the PWS duck populations were 1-3 orders of magnitude lower than that shown to cause demonstrable effects in mallards. The Exxon Valdez oil spill changed much about what is now done to prevent such spills, to be better prepared for response, and to select shoreline cleanup methods, as well as to understand the acute and long-term impacts of oil on a wide range of species, communities, and habitats.
ated considerable interest and was used as a primary source of information by industry, government agencies, scientists, and the general public. By the mid-1980s, it was realized that an update to this important document was needed, and the U.S. Coast Guard requested that the Ocean Sciences Board of the National Research Council (later the Board on Ocean Science and Policy [BOSP] and now the Ocean Studies Board [OSB]) undertake a new examination of this subject. The BOSP appointed a steering committee consisting of six members from academia, government service, and industry to be responsible for updating the 1975 NRC report. A public meeting was held in 1980, at which representatives from the oil industry, universities, government, and environmental groups were invited to make presentations on topics important to the committee. In early 1981, 46 expert contributors were invited to prepare summary papers on all aspects of petroleum in the world’s oceans, and later in 1981, an international workshop was held to discuss the main issues of petroleum hydrocarbon inputs into the marine environment. In early 1982, the steering committee began preparing the new report, which was published in 1985. The report Oil in the Sea: Inputs, Fates, and Effects (NRC, 1985) generally followed the same format as the 1975 report but was much more detailed and contained significant new data and information that had been acquired since the earlier report. The 1985 report has served as a seminal publication that documented petroleum hydrocarbon discharge into the marine environment and the fates and effects of this discharge.
Prior to and since the 1985 NRC report Oil in the Sea, there have been a series of studies undertaken to examine the load of petroleum hydrocarbons to the marine environment. The majority of studies has focused on quantifying the volume from tanker spills, and many have been conducted under the auspices of the International Maritime Organization (IMO) or its Joint Group of Experts on the Scientific Aspects of Marine Pollution (GESAMP). One of the most recent GESAMP reports, Impact of Oil and Related Chemicals