By Marcus Drymon, Jennifer Hadix, Shauna Kuhn

In order to best quantify the effects of the Exxon Valdez oil spill in the Prince William Sound, a better understanding of the role of oil in the crustal ocean factory must first be sought. It is important to understand that oil is naturally produced in the ocean via processes that occur in the sediment. This oil leaks into the water column at fissures and cracks. With this in mind, oil is classified as a pollutant, and the ocean has developed its own "recycling system" to deal with naturally occurring petroleum. Pollutants occur naturally in the sea, and when their levels exceed natural background levels, they then become contaminants. Major sources of anthropogenic oil in the sea are usually chronic ones, such as tanker operation (bilge pumping), sewage outfalls, and runoff. The fate of oil dumped in the sea is controlled by one of several factors: chemical composition, sea state, wind speed, temperature, the geology of the sea floor, and biological activity. If the sea state is calm, the oil will form a slick, which is subject to physical processes in the ocean, such as advection and turbulent mixing. This can help disperse the oil in addition to making it form emulsions (little tar balls). Some of this oil is photochemically degraded, some sinks as POM, some gets incorporated into the biota, etc. Once in the sediments, the oil persists for quite awhile. The toxic components of the oil remain toxic to the benthos once buried in the sediments. Oil not incorporated in the sedimentary record is equally if not more so harmful to aquatic life, interfering with vital reproductive processes, which will be touched on later in the paper (Libes 92). Research published early this year indicates that oil persists in the environment in toxic forms longer than we thought. For at least five years after the Exxon spill, unweathered oil was being found on beaches 500 km from the Prince William Sound. The mousses (oil slicks that have mixed with water into an emulsion) that are moving this oil such long distances are keeping it in its toxic state by preventing it from being broken down and processed by the sea. It was originally thought that weathering, along with other processes would remove the oil from the beaches and rocks in the upper tidal zone, but it is apparent that estimates as to the time frame of that removal were wrong. Measurements taken up to 1994 showed "negligible changes in polynuclear aromatic hydrocarbons compared to the 11-day-old Exxon Valdez crude." (Irvine 1999). This means that, in some part because of the structure of these mousses, the oil is being transported longer and being broken down slower than we ever thought. Not only that, but recent studies spurred by the ten year anniversary of the spill say that the polynuclear aromatic hydrocarbons are much more toxic than we ever thought. Polynuclear aromatic hydrocarbons are the main structural component of oil and are often seen written as PAH’s. Publications after the spill reported PAH levels ranging from 51.4 all the way down to 4.4 ppb, and these papers cited that these levels could lower reproductive fitness, growth rates, or kill the fish (Holloway 1999). One scientist described the harm to fish from PAH’s as "taking a shotgun to their DNA." (Holloway 1999). We now know that PAH levels of 1.1 ppb increased fish mortality. Not only that, the same scientists found that the effects of fresh verses weathered oil were about the same (Holloway 1999), indicating that we are looking at long term time scales before we start to see significant decomposition of the oil from the spill.

Prince William Sound is an enclosed sea in Alaska just east of Anchorage. There are many mountainous islands, glacial fjords and protective embankments. The sound is one of the largest undeveloped marine ecosystems in the United States and one of the continents largest tidal estuary systems. The area is virtually untouched by the growing population of the world.

On March 24, 1989 the supertanker Exxon Valdez is grounded on Bligh reef, 40 kilometers out of port. It only took 5 hours for 11 million gallons of oil to spill into the sound. The initial response had three priorities. First, they needed to contain the initial spill. They wanted to keep the oil from spreading too far. Second, they needed to prevent any more oil from spilling because there was still 80% of the tanker's oil still left on the barge. This was also their final concern, to remove the remaining 51 million gallons of oil. The scientist’s initial response was different. They scrambled to take pictures and samples of the shoreline before the oil reached them. They needed to do this because there was little information on the Alaskan ecosystem to base rehabilitation efforts on.

The oil could not be contained quickly enough because there was an eighteen-hour delay in the cleanup equipment reaching the spill. The containment barge had been stripped of its gear prior to the spill and it took time for the cranes to reload the large, heavy equipment. It was here that they lost the opportunity to contain the spill and limit the damage. If there had been a better knowledge of the seasonal distribution and movement patterns of the water, some major spreading could have been prevented. Approximately sixty hours after the spill there was a winter windstorm that stirred up the sound and spread the six-kilometer long slick to sixty-four kilometers long. It didn’t help containment that the booms that were used to prevent the oil from spreading were breaking and constantly needed to be replaced. Because of all this a total of ten thousand square miles of the sound were oiled. Detectable amounts of oil were found nine hundred kilometers from the crash sight.

Sea otters (Enhdra lutris) occur year round in the shallow coastal waters of Prince William Sound and the Gulf of Alaska. Several variances exist in the estimates of total sea otter population loss based on differences in study techniques and information. One study concluded that in the unoiled areas, shoreline sea otter density in the summer of 1989 was approximately 14% greater than pre-spill density. In the oiled areas, shoreline sea otter density declined approximately 35% during the same interval. Surveys conducted in the summer of 1990 showed further declines in population density in the oiled areas to 54% below pre-spill values. This indicates a significant first year effect of the oil spill on the Prince William Sound otter population. The further decline suggests a continuing oil effect (Burn 1994). Another estimate based on studies of pre and post spill population densities and sighting probability approximated the total loss at 2650 sea otters (Garrot et al. 1993). An approximation based on carcass recovery estimated the total loss at 2209 sea otters. It is generally estimated that approximately 3500-5500 sea otters died as a result of the oil spill (Burn 1994).

Inhalation of vapors and direct consumption of the oil leads to a variety of ailments in sea otters. Oil contaminated otters rapidly become hypothermic due to the decrease in the fur’s insulating capabilities. The otters then attempt to remove the oil by grooming which results in the ingestion of crude oil. Feeding is drastically reduced and energy stores are rapidly depleted due to the onset of anorexia. Exposure to the oil causes interstitial pulmonary emphysema, which is the accumulation of air bubbles within the connective tissues of the lungs; thus respiration is comprised. A powerful stress reaction occurs, resulting in gastric erosions and hemorrhaging in the gut. The combined effects of these ailments overwhelm the otter, and shock ensues. Seizures usually follow, and eventually the animal dies. Some otters succumb to hypothermia rapidly and no lesions are formed; others live long enough to develop some or all of these ailments (Lipscomb et al. 1994).

Harbor seals (Phoca vitulina richardsi) also occur year round in Prince William Sound and the Gulf of Alaska. Potential effects of the oil spill were of particular concern because harbor seal populations had been declining substantially since the 1970’s. pre-spill decline estimates from 1984-1988 indicated an 11% average annual decline at oiled sites and a 13% average annual decline at unoiled sites. Post-spill decline estimates indicated the average number of seals at oiled sites had declined 43% compared to an 11% decline at unoiled sites (Frost et al. 1994). Another study found that the harbor seal population in the sound has been declining since 1984 with an overall population reduction of 63% through 1997 (Frost et al. 1994). It was also found that 26% fewer pups were produced at oiled sites in 1989 than would have been expected without the spill (Frost et al. 1994).

Of 585 seals observed in oiled areas in May 1989, 81% were classified as being oiled. Natural cleaning was offset by continued exposure to oil on rocks and algae; contact with the oil produced a variety of ailments in harbor seals (Lowry et al. 1994). The oil caused an interference with locomotion. One observation told of two seal pups that were so heavily oiled that they drowned because their flippers were stuck to their bodies and they couldn’t swim (Williams et al. 1994). Oiling of the fur reduces its insulative value; this is not likely to be a major problem for adult seals because they rely primarily on blubber for insulation. However, the thin blubber layer of neonates provides a poor thermal barrier if the fur is contaminated with oil. Contact with oil can irritate sensitive tissues, especially the mucous membranes. It was noted that heavily oiled seals appeared to have difficulty keeping their eyes open, and conjunctivitis was common in collected seals. Dry, scaly skin occurred significantly more in oiled animals, and seals with eroded tissue around the margins of the nostrils were also seen. Most detrimental was the oil’s pathological damage to the nerves of the brain. Hydrocarbon toxicity resulted in brain lesions in the thalamus, the part of the brain responsible for sensing the environment. This may have lead to thermoregulatory problems due to the inability to determine and control temperature changes. The brain lesions accounted for behavioral changes such as lethargy, disorientation and decreased response to human activity. If severe, the lesions could have caused the affected seals to have extreme difficulty in performing normal tasks such as swimming, feeding and diving (Lowry et al.1994).

Killer whales (Orcinus orca) also inhabit Prince William Sound and the Gulf of Alaska. The close social structure of killer whale pods enables researchers to regularly study the appearance of pod members. A resident pod of the sound comprised of 36 individuals before the oil spill dropped to 22 individuals over a period of three years after the spill. Given that the mortality rate of killer whales is 2.2% per year, a loss of 14 individuals suggests that the pod was affected by the oil spill (Matkin et al. 1994).

The conflicting viewpoints surrounding the Exxon Valdez oil spill recovery make its discussions feverish as well as highly debatable. Even so, some facts remain relatively undisputed. Two species are listed as recovered, the Bald Eagle and the river otter. Eight species are listed as recovering, including the sea otter. Six species are listed as unrecovered, and the harbor seal is included in that group, and four species are of unknown recovery (ten year statement). To further complicate matters, damage assessment is made even harder because the actual scientific definition of damage is hard to agree on. The Oil Spill Trustee Council defines species recovery as a return to pre-spill population numbers or an increase in those numbers. Furthermore, it is impossible to measure the recovery of an entire ecosystem based on the studies of a few species, when the oil affected thousands of species. Another factor complicating the damage assessment issue is a lack of pre-spill species abundance information. It is impossible to assess whether a species has recovered or not if their original population dynamics are unknown. The time scale further complicates issues. As mentioned earlier, these effects are hard to measure on such a short time scale. I believe some of the effects of the spill will not be evident for years to come. Finally, other natural disaster events could have a role in the way the ecosystem functions today. For instance, the recent El Nino events have had an effect on the populations of certain species. The Great Alaskan Earthquake of 1964 could have also played a role in the current functioning of the ecosystem in that area, and it is possible that the consequences of these disasters are being seen now, making it impossible to differentiate between the changes due to the oil spill and changes due to previous natural disasters (Exxon Statement).

Although it is a hard question to examine, there comes a point when we must ask ourselves "was the whole rehabilitation effort really worth it?" In order to attempt to objectively answer this question, this paper will concentrate on one of the more popular rehabilitation species, the sea otter. Sea otters were often the center of the rehabilitation efforts; in part because they are relatively accessible, in part because of their vulnerability, and in part because they are marine mammals. Volunteers were able to get to get to a fair number of sea otters (357), and of those, 197 lived. On the other hand, it is estimated that thousands died before help could arrive. Some of the animals taken to the centers would have certainly been better off left to their own device. Of the ones released, 45 were equipped with transmitters, and in the following spring, 22 of those were dead or missing. As far as the monetary aspect of the problem goes, it cost about 80,000 dollars per otter released into the wild. Would the money have been better spent to help the otters in a different way (Estes 1998)? Some of the species (clams, mussels, kelp, algae, etc.) received a 1-2 punch, meaning they were first subjected to the oil spill and then to our meddlesome cleanup efforts, including hot water washes and the introduction of oil eating microbes, not to mention the direct impacts of so much human contact (McFadden 1999). Given the magnitude of the spill, it remains unclear if the gargantuan effort to rehabilitate these creatures was worth it.

OK, what do we do next time? At least in the Prince William Sound, standards and regulations have changed drastically. Tanker safety has been improved, an despite the high cost of double hull tankers, companies are being forced to make the move. These double hull tankers could drastically reduce the amount of oil spilt in a future spill. Tankers have modifies routes, new technology, more frequent inspection, better employee background checks, and overall better training programs (1999 Update).

Unfortunately, humans usually need a catastrophic disaster, such as what happened in Alaska, in order to instigate more precautionary measures. If one good thing lurks in the wake of the terrible destruction in the Prince William Sound, it would have to be the increased awareness brought about after the spill. Was the ecosystem damaged? Sure. Is it still recovering? Probably. Will it ever recover to some extent? Of course.

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