All around the world, people watched in horror as a deadly black tide swept across Prince William Sound and out onto the coast of the Kenai Peninsula after the grounding of the tanker Exxon Valdez on March 24.
More than 10 million gallons of Alaska North Slope crude rolled through the environment like the Black Death. People watched the destruction, and they began to grieve that the virgin waters of this spectacular marine wilderness had been destroyed.
Alaskans watched black gunk wash up several inches deep on their beaches and wondered if it would ever disappear. They worried about the crude oil penetrating the food chain where, they thought, it would remain forever.
As the spill spread, human fears for the fate of the Sound took on an almost mythic hysteria.
"The giant amoeba has finally swallowed the world," Alaska Department of Fish and Game spokesman Jon Lyman proclaimed from Valdez on Day 10 of the spill. "The environmental disaster is here."
The nightmare long feared by many Alaskans had, indeed, arrived at last, but like all environmental nightmares it was one from which nature was certain to wake.
Scientists do not downplay the devastation that poured through the Sound in the first weeks after the Exxon Valdez hit Bligh Reef, but they say studies of past spills indicate the longterm implications of North America's largest oil spill should be limited.
The Sound has been damaged. It has not been destroyed.
Studies of other spills indicate a recovery will begin within the year and be complete within a decade or two.
"Hydrocarbons are natural, not alien materials," writes J. Davenport of the University College of North Wales in Great Britain. "The bulk of hydrocarbons, even including . . . carcinogens, are produced by living biota and are thus a normal part of the chemical habitat of organisms."
The oil spilled in Prince William Sound came from the decomposition of plants and animals that lived on the North Slope of Alaska millions of years ago. This oil might have created a disgusting catastrophe, but it was not the kind of catastrophe caused by an alien, manmade substance destined to linger in the environment for ages.
As Science Magazine noted after the East Coast was swept by fears about the 7.7 million gallons of fuel oil that leaked from the Argo Merchant off Nantucket Island in 1976:
"A wide variety of animals and microorganisms metabolize or detoxify hydrocarbons . . . Petroleum compounds are not concentrated in food chains."
Marine organisms that ingest hydrocarbons in low enough concentrations to survive are able to purge themselves of the petroleum products once clean water becomes available. Some oilcontaminated oysters removed from bays in Brittany, France, after the spill of the Amoco Cadiz in 1978 were placed in clean water where they cleansed themselves and eventually became marketable.
As for the live oysters that remained in the area of the 65million gallon Cadiz spill the world's largest oil spill time, and the always shifting tides of the ocean, helped to cleanse them. Eleven years after the Cadiz oil hit the beaches, traces of the spill can still be found buried in the beaches in some parts of Brittany, but the environment has largely healed.
As early as six years after the spill, Time magazine was reporting that "most evidence of the accident has disappeared. The coastline is clean and the shore birds have returned. Scientists say that natural processes such as waves and tides dispersed much of the pollutant and that bacteria broke down some of the crude. An estimated 18,000 tons of oil deposited on the sea floor have all but vanished."
Wall Street Journal reporter Philip Revzin reported from Paris this year, 11 years after the spill, that French experts have concluded that most of their fears about the Cadiz spill proved to be unjustified, at least in the long term.
"All is back to normal," Lucian Laubier, chief scientific adviser to the French oceanic research institute, told Revzin.
The French undertook massive cleanup efforts after the Cadiz vomited Middle Eastern crude all over their coast. But when the tanker Metula went down in the Strait of Magellan in 1974, spilling 17 million gallons of Arabian crude, the Chileans made no attempt at a cleanup.
The Metula spill a spill more than one and a half times the size the lost cargo of the Exxon Valdez was left to nature. Today, 15 years later, oil remains in the area of the wreck, according to scientists, but it has generally solidified into asphalts or weathered into a brown gunk free of most toxic components. The Metula oil has disappeared into the great mixing bowl of the sea or become a semipermanent part of the beaches along the strait.
". . . In several areas algae are now attached to gravel on top of the pavement surface," research scientist Erich Gundlach of Columbia, S.C., reported after visiting the beaches fouled by Metula 61|2 years after the spill. "In areas that were heavily impacted and are now free of oil, there has been a tremendous repopulation of the areas by mussels."
Sheltered marshes, however, still held pockets of crude, and Gundlach predicted the oil could linger there, hidden beneath new growths of grass, for up to 100 years. That is a long time in human terms, but it is not all that long in environmental terms.
Scientists compare the damage done by an oil spill with that caused by a forest fire. Both begin with widespread but seemingly random destruction. Some areas are left largely untouched.
The diversity of plant and animal life is disrupted, but recovery begins fairly quickly. New plant growth often returns within a year. As it does, a steady process of colonization by other life begins.
Some symbols of the disaster remain for a long time be they the hulks of burned trees or the asphalts of spilled oil. But the recovery goes on around them, progressing through successive stages beginning with a monoculture of life dominated by a few opportunistic species and ending with a diverse culture with many species.
This is the kind of marine culture that existed in the Sound before the spill. This is the kind of marine culture that will return if future spills can be prevented.
Here, in brief based on a review of scientific research is the likely scenario for what happened in the aftermath of the 10 million gallon toxic bath provided by the Exxon Valdez, and what is likely to become of the oilpolluted environment:
TOXINS EVAPORATE QUICKLY
Immediately after the oil hit the water, and for the period over the next several hours and into the next few days, the lightest fractions of the crude the hydrocarbons that would be refined into gasoline and similar chemicals began evaporating or dissolving.
Anywhere from 30 to 50 percent of the spilled oil might have vanished from sight this way. Rapid evaporation over the first 24 to 48 hours of any spill removes many of the most toxic compounds from an oil slick, according to chemist James R. Payne, an expert on Alaska North Slope oil in the environment. These chemicals quickly pass into the atmosphere where they fade into the immense volume of air.
Only a tiny volume of oil actually dissolves into the water, Payne said, but it enters the system in the form of powerful solvents benzenes, toulenes and napthalenes. These chemicals reach their peak concentrations shortly after a spill, and then begin a rapid decrease, but they can still be deadly to marine life.
The solvents are strong enough to dissolve the cell walls of bacteria and the plankton that form the vital base of the food chain. Each ounce of seawater teems with these plants and animals.
How much a spill damages them depends on how large an area is hit and how quickly organisms respond to the disturbance. Oil can harm microcellular life, but it can also aid it. Many bacteria possess the ability to become oil eaters.
This is the process of biodegradation of oil. Bacteria, in effect, begin feasting on the hydrocarbons, growing and reproducing, doubling and redoubling their populations as the oil is consumed.
"Observations from the Argo Merchant spill (off New England) and the Amoco Cadiz suggest that the bulk of the oil remains in the upper 10 to 20 meters (30 to 60 feet) of the water column and that levels return to some background level within weeks, or at worst, a couple of months," marine ecologist J.H. Vandermuelen told a conference on oil pollution in 1982.
Norwegian scientist Rolf Lange tracked an experimental test spill in the North Atlantic in 1982 in a search for evidence that oil destroys plankton. He found none.
SOME BEACHES POISONED FOR YEARS
As the oil from the Exxon Valdez moved across Prince William Sound, stirred by winds and tide, it forfeited many of its toxic compounds to evaporation and dissolution, but the oil that hit the beaches of Naked, Knight and other islands was still a deadly brew.
Here, on the intertidal beaches and along the shallow water below the low tide mark, tens of thousands of gallons of crude began to sink into the sand and gravel and rock. Marine life from flat worms to urchins to mussels to small crabs began to choke on this oil. Shellfish were especially vulnerable.
In the bays of Aber Wrac'h and Aber Benoit on the coast of France, the oil from the Cadiz killed 20 to 50 percent of the oysters being raised in the mariculture industry. Many of the surviving oysters were so heavily contaminated they had to be destroyed.
New oysters introduced into those waters the next year quickly sucked up oil leaking from contaminated beaches. Only in the areas where oiled sediments had been removed and replaced was it possible to raise uncontaminated oysters the year after the spill, scientists reported.
Shellfish have proven highly vulnerable in spill after spill. After the Arco Anchorage dumped 239,000 gallons of Alaska North Slope crude at Port Angeles, Wash., in 1985, scientists reported a massive kill of shellfish despite largescale cleanup efforts. The state of Washington eventually billed Arco more than $20,000 for killing 12,468 pounds of clams and cockles.
And scientists agreed Arco had done everything possible to save the shellfish of the port. The company used bulldozers and water jets to blast buried oil out of the beaches. The technique was credited with helping the waters and the environment of the port return to near normal in about three years.
At other spills, where only the surface oil has been removed, oil left trapped in beaches has become a ticking time bomb waiting to destroy shellfish. As waves stir the sands, the oil moves about in the sediments where clams and other creatures live and feed. Slowly, this constant exposure to low level hydrocarbons begins to poison life.
At Baffin Island in the Northwest Territories of Canada, scientists from four nations spent $7 million studying this phenomenon. They spread oil onto the arctic beaches and waited to see what would happen.
For years, waves and tides tried to pound this oil out of the ground. But the cleansing efforts of the sea succeeded only in picking up contaminated sediments and moving them to greater and greater depths in the water along the beaches. Sediment dwelling creatures originally spared by the experimental oil spill began to fall victim.
The French saw the same thing after the Cadiz. The damage to shellfish continued for two to three years after the spill.
Gary A. Sergy of Environment Canada reported that few of the marine animals contaminated by leaching oil died, but their growth slowed or stopped and their populations suffered as reproduction decreased. And these contaminated animals, Sergy added, could poison the fish, birds and mammals that feed on marine life.
Once contaminated, shellfish beds can remain polluted for a decade or more. Scientist A.D. McIntyre of the marine laboratory at the Department of Agriculture and Fisheries for Scotland has reported intertidal crab and clam populations still suffering from hydrocarbon contamination six to eight years after spills in England and Canada. Scientists at the Woods Hole Oceanographic Institute in Massachusetts say it took razor clams, fiddler crabs and other shellfish 20 years to completely recover from a spill of highly toxic diesel fuel in Buzzards Bay, Mass.
Shellfish cannot begin to recover until the beaches are free of oil. The cleaning can be done by either man or nature. Man can do it relatively quickly. How long it takes nature depends largely on the composition of the beach.
Rocky headlands, such as the Chiswell Islands near Seward, clean themselves naturally within days or weeks. Marshes and sheltered tidal flats might take a decade or more to regurgitate their oil.
The extensive marshes along the Brittany coast took 10 years to recover from the Cadiz spill. They were ill long after nearly everything else had healed. Two years after the spill, oil was still pooled on the surfaces of the marshes. Animals had died or deserted the area. The grasses and most other plant life was dead. Trenches were dug to try and drain oil from the marshes. Some marshes were bulldozed, a tactic scientists later regretted.
In areas where surface oil was mopped off the marsh and picked up without disturbing sediments, some marsh plants survived, Gundlach reported. But in those areas where surface sediments were removed, soil nutrients were reduced and nothing grew.
The Exxon spill avoided the most important marshes in Prince William Sound. By luck, the slick moved west out of Sound, slipping steadily away from the grass flats of the Copper River Delta where the environmental damage could have been devastating.
Instead, the most damage done by the oil will likely be seen on sheltered tidal flats, of which there are relatively few in the Sound and along the Kenai. In these areas, the oil will slowly mix with sediments. Unless the crude is cleaned up, it will threaten marine life until it solidifies into asphalts.
The vulnerability of marine life to oil is intertwined with the different beach types. Shellfish tend to concentrate in the sheltered tide flats where oil pools. Birds favor the marshes where they are easy victims for oil. Starfish and crustaceans favor rocky, subtidal shores where there is less risk from oil. Fish move offshore where there is even less risk.
Plants and animals moving free in the ocean, or those that are associated with rocky or gravel beaches, have shown strong abilities to endure oil spills. Heavily oiled kelp survived the Cadiz. French kelp farmers were back to work the year after that oil spill.
"No significant effects of the Amoco Cadiz spill have been documented for the production of kelp or other algae, which are extensively harvested in Brittany for fertilizer and silage," Gundlach reported five years later. "The growth of kelp appeared impeded in April 1978, but returned to normal for the balance of 1978 and was apparently stimulated in 1979."
Kelp beds oiled in the Port Angeles spill also survived unharmed.
Scientists who monitored French cleanup efforts said it was a mistake to spray oilcoated, rocky beaches with highpressure, hot water. The water blasted loose all plant life, the scientists said, and algae had a difficult time recolonizing bare rock. Where plant life remained on the rock even where it might have been killed by hot water or oil algae either survived or quickly reestablished themselves, scientists reported.
MOST FISH ESCAPE OIL SPILLS
As the oil slick from the Exxon Valdez rolled across Prince William Sound, the toxic benzenes and toulenes that could kill fish settled into the water beneath the slick. This toxic water would have been lethal for fish, but not a lot of them were vulnerable. Larva and fingerlings that would normally inhabit the upper layers of the water column weren't there yet.
Herring were just returning to the Sound to spawn. Other species had yet to begin their spawning. Juvenile salmon had yet to emerge from the streams of their birth.
As the days passed after the spill, the toxins in the water diluted, becoming less and less dangerous. Salmon probably escaped the spill, but some of the herring that spawned on oiled beaches likely sacrificed their young. Studies done in the vicinity of the Argo Merchant of New England in 1976 concluded that fish eggs that came in contact with oily water quickly die.
Nearshore spills pose greater risks than the spill of the Argo Merchant on high seas, McIntyre reported, "(but) even in these situations effects on fish are difficult to detect. After the Tseis spill in the Baltic (Sea), herring continued to migrate through the area, and contamination was not detected in their tissues. There was apparently some reduction in spawning the following spring, but investigators did not attribute this to the spill."
Fish kills actually attributable to oil spills have indeed been uncommon.
Salmon and rainbow trout being raised in net pens within a mile of the Arco Anchorage spill showed no signs of hydrocarbon contamination. Scientists concluded there just wasn't enough oil dissolved in the water to affect the fish.
In the much larger Amoco Cadiz spill, several tons of rockliving fish were killed within a twomile radius of the wreck, and McIntyre said, "enhanced proportions of diseased fish were reported sometime after the spill, and one yearclass of flatfish was thought to have been reduced. (But) it is of interest that this is probably the one welldocumented spill in which such effects are recorded."
The diseased fish in the area of the Cadiz suffered from fin rot. The problem persisted for a couple of years, then disappeared. French scientist G. Conan, in a report on the longterm effects of the Cadiz spill, said that studies showed that the growth of fish in the immediate area of the spill slowed after the accident, but returned to normal in a year. Longterm damages to the fisheries were never documented.
Computer studies of worstcase spill scenarios for the North Sea spills that would come at the peak of spawning have concluded that the maximum damage would be a slight reduction in overall yield for one year. It would be a reduction so small, scientists probably couldn't detect it against the background of normal variability in fish stocks, according to McIntyre.
He contends the only real oil problem facing fisheries centers on the contamination of fish. Even a small amount of oil can significantly alter taste and make fish unmarketable.
"The tainting problem is serious and must not be underplayed," McIntyre writes. "At its worst it can bring severe financial hardship to individual fishermen and can close grounds for years. But there does not appear to be a public health problem and the impact of tainting must be regarded as local rather than even regional and recognized as one that can be corrected with time."
He dismisses the risks of oilfouled fish to humans. Crude oil contains polynuclear aromatic hydrocarbons that have been linked to cancer, McIntyre said, but human exposure to those chemicals in seafood would appear insignificant next to the regular exposure to them in fresh vegetables and smoked foods.
Commercial fishermen from Cordova, Valdez, Whittier and Seward could face financial problems if tainted salmon show up in the Sound this summer, but the consequences to the fish themselves appear almost insignificant. Salmon, with noses sensitive enough to guide them back to the streams where they spawned, are also adept at avoiding oil. They can smell the oil in the water long before it becomes a danger.
BIRDS ARE AMONG MOST VULNERABLE
Wherever oil has been spilled on the ocean, seabirds have died by the thousands. It is estimated the toll of dead birds numbered 15,000 to 20,000 after the Cadiz. Many of the birds were migrants on their way to nesting colonies in the British Isles. Many of the carcasses were never recovered.
The numbers of dead birds associated with any spill are staggering. It looks bad, the scientists admit, but they are still debating the significance of these deaths.
Natural death rates in bird populations are high. Up to 30 percent of some populations die each year. Scientists have yet to determine whether birds killed in an oil spill represent a part of the population that would have died naturally or an addition to the annual death rate. Conan concluded the Cadiz spill could alter the population of birds in the the North Sea area for decades.
"Seabirds have life expectancies of up to 20 years and an isolated population may need up to 60 years for its recovery under stable environmental conditions," he reported. He argued the Cadiz spill played a part in destroying France's puffins. But other scientists note the population of those birds was in serious decline before the oil spill.
Whatever the case, there is no doubt that seabirds are highly susceptible to oil. Almost 4,000 birds were believed to have been coated with oil and killed by the 239,000 gallon Arco Anchorage spill at Port Angeles. Most of the dead birds were never recovered.
Efforts were made to save 1,917 birds that were brought to a rehabilitation facility. About 80 percent of them died anyway, according to scientists from Arco. Longterm monitoring of bird populations at Port Angeles, however, never revealed any evidence the deaths caused longterm declines in bird populations in the area.
Alaska has been lucky if anything to do with the deaths of tens of thousands of birds can be called lucky in that the Exxon spill avoided some key bird areas, and hit hardest at bird populations that are considered relatively stable scoters and other ducks, and murres. No puffins have turned up dead yet, and the vital bird resting area on the Copper River Delta remains untouched by oil. The world's entire breeding population of western sandpipers and American dunlins passes through that area, not to mention thousands of swans and other waterfowl.
Bob Gill, a migratory bird researcher with the U.S. Fish and Wildlife Service, believes the birds arriving now will avoid obviously oiled areas. The dangers to the birds, he said, would come primarily from feeding on toxic materials that were not obvious, or from stress if the oil has damaged enough beach to force the birds to compete for food.
Little is known about the toxicity of oil to the birds that swallow it, although there are reports eagles have died from eating oiled birds. Certainly, a diet of hydrocarbons would seem less than healthy for America's symbol, but eagles have been dining at dumps in Alaska for years eating all sorts of things and surviving.
Alaskans will have to wait for new studies to determine whether eagles and other scavengers from gulls to ravens to bears fall victim to oiled carrion.
OTTERS ARE MAJOR VICTIMS
Knowledge about the dangers of oil to sea otters was limited before the Exxon spill, but biologists always expected the little predators to be highly vulnerable. Unlike other marine mammals, otters have no blubber. They are vitally dependent on clean fur for insulation.
Scientists who have spent years observing otters say the animals spend nearly all of their time eating or cleaning their fur.
The first indication of how important clean fur was to an otter came when the U.S. Fish and Wildlife Service first tried to transplant otters from Alaska to areas of the West Coast where the animals had been exterminated. Large numbers of captive otters died. Biologists finally discovered that in handling the otters, the otters were getting dirty, and that was killing them.
Now biologists are learning a new lesson about otters: The efforts of the animals to keep their fur clean can prove deadly in the midst of an oil spill. Otters that survived the initial onslaught of the Exxon spill did so by licking up the oil that was ruining the insulating value of their coats.
The oil they licked up, however, proved as deadly as an oiled coat. Dozens of otters rescued from the Sound died in captivity with oil in their guts. The spill was two weeks old before R.V. Chalam, a toxicologist from the University of San Diego, came up with the idea of feeding the otters a product called Toxiban. An activated charcoal mixture, Toxiban was developed for treating farm animals that swallow pesticides. Toxiban bonds with the chemicals and passes them safely through the animal.
After otter treatment specialists started using Toxiban, survival rates improved. But there are still far more otters dying than are being saved.
Close to 600 of the Sound's estimated 10,000 otters are known to have died already. Nobody knows how many others are dead but undiscovered. Nobody knows if the survivors can stay out of the oil still drifting around.
Can otters learn to avoid this danger? Past tests have been inconclusive, according to California researchers Robert Cimberg and Daniel P. Costa. In pool studies, they reported, otters swam into oil without noticing. The normal swimming position for an otter is on its back, motoring along without looking where it's going.
But Cimberg and Costa noted that Japanese poachers have effectively used petroleum products to herd otters away from shore in the past an indication the animals might have a natural and healthy dislike for oil.
What could prove most important to the survival of the Sound's otters in the years ahead is what becomes of the Sound's shellfish. Otter populations were believed to be at or near their peak population when the oil hit. There was speculation the animals might be approaching the carrying capacity of their habitat. What if the food available to otters has been reduced by oil?
Otters could begin starving. That is a normal occurrence in the Alaska winter already. Scientists report 16 percent of the oiled otters picked up in the Sound died before the oil spill, probably from starvation or illness. The animals starve easily. Each day, they must consume food equal to almost 30 percent of their body weight. A 150pound man with similar survival requirements would need to eat 45 pounds of food a day.
Otters simply aren't as lucky as the marine mammals born with thick layers of fat. Most of those animals are given a good chance of surviving the spill, although scientists admit there is little evidence on which to base that conclusion.
MARINE MAMMALS AND OIL
The Exxon Valdez offers the first chance to study how seals, sea lions and whales interact with a major oil spill. Other spills have all taken place away from marine mammal populations, in areas where marine mammals had been exterminated or significantly reduced.
Scientists now have a chance to find out what risks oil poses to those creatures. So far, they have largely avoided the spill. That should save them from contamination, but will they be cut off from important feeding areas?
And only time can tell how long the oil will keep these marine mammals from their favored hunting grounds. Only time will tell exactly how long the oil lasts in the Alaska coastal environment. Only time will tell how long oiled beaches emit their toxic load.
As the Alaska North Slope crude drifts around in the Gulf of Alaska, it is weathering and breaking down. Some of it is being consumed by bacteria. Some is sinking drop by drop into the water. Some is sticking to the beaches, although in its present state Payne believes beach deposition is minimal.
Past studies have shown that the heavily emulsified oil that is 50 percent or more water washes off beaches almost as easily as it washes on. The oil that is not grubbed by human hands will disappear. It will break up at sea or oxidize or attach to particles of sediment and sink or get tossed far enough up on to a beach where it can no longer be washed away, where it can start forming into asphalt.
This is how much of the 10 million gallons of Alaska crude will eventually disappear. Instead of coming out of the tailpipe of a car and fading into the polluted skies over California, it will slip into the now polluted waters of Alaska.
Its legacy will become quickly invisible to the untrained eye. The beaches of the Sound might even look great by this time next year.
"(The) exuberant growth of algae in the first, second and third years, (gives) a false impression of health and recovery to superficial observers," notes ecologist A.J. Southward of England. But scientists know the recovery of the full diversity of marine life does not happen that quickly.
An oil spill, they say, is never as bad as people at first assume, and the biological recovery is never as quick as people think. It will be 10 years or more before Prince William Sound is like it was before the Exxon Valdez struck Bligh Reef, and if past spills are any indication, most people will have forgotten about this disaster long before then.
As Peter Koenig wrote in Audubon Magazine a mere three years after the Cadiz went down:
"The world public no longer cares. The shock value of supertanker accidents is gone. Scientists have not been able to prove that oil in the seas causes irreparable damage, or that it poses a health hazard to humans."
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