Oil Spill Sparks New Approach to Science : Research: As an antidote to isolated study, a center examining the impact of the Exxon Valdez disaster is taking an interdisciplinary route.
Like the proverbial silver lining around every cloud, the Exxon Valdez oil spill that decimated the rich fishing areas of Prince William Sound has spawned a new era in scientific research of the sea.
The oil that gushed from the grounded tanker on March 24, 1989, could not have come at a worse time--blackening the tranquil waters of the sound just as young salmon were entering the sea and as the zooplankton that could keep them alive was beginning its “spring bloom.”
Early expectations were for the worst, suggesting that the islands and the waters of the pristine sound would be devoid of life for generations to come. That has not happened, as evidenced by the near-record-breaking fishing seasons of the last couple of years.
What is perhaps most surprising is that despite the scientific research focused on the area after the spill, nobody really knows just how much damage the oil caused. Scientists say that is because earlier research had been so compartmentalized that no one knew exactly what the sound was like before the accident.
Even the impact on zooplankton, the tiny organisms that form the first ladder of the food chain, was never measured, according to Gary Thomas, chief scientist with a new organization that could change the way many scientists go about their research.
That oversight is “amazing,” Thomas says, because laboratory research indicates zooplankton is vulnerable to oil spills.
“They didn’t look at it even though the spill came during the spring bloom” when the zooplankton population blossoms into a crucial food resource for marine animals, he said.
The haphazard research that followed the spill is typical of the way scientists carry out their work, Thomas says. Instead of sitting down and sharing their data with scientists from other fields, he says, they tend to work in isolation, often ignorant of what colleagues in related disciplines are doing.
For decades now, some scientists have preached that that is a lousy way to do research. Many have called for interdisciplinary programs that can look at the interactions of different species in an entire ecosystem, not just the behavior of its individual members.
But for Thomas, that concept remained a dream until recently. It took 11 million gallons of crude oil, spilled on the resource-rich waters of Alaska, to bring it to life.
Thomas heads the 2-year-old Prince William Sound Science Center in the coastal community of Cordova, funded primarily with about $1.5 million a year from the $5-billion judgment against Exxon Corp. arising from the oil spill lawsuit. Drawing on experts from all over the country, the center is carrying out a comprehensive study of the entire ecosystem of Prince William Sound.
Others have talked about interdisciplinary research, he says, but “we’re unique because we have a program that was funded.”
Scientists at the center, which employs about 30 people, are using a wide range of new tools--from satellite imaging to underwater acoustics--to determine the abundance of marine animals in the sound. They also rely on the expertise of local fishermen, and even do a little fishing themselves just to make sure their instruments are providing the right clues about the types of animals that are there.
Their research may never be able to document all the damage from the oil because data prior to the spill is so limited. But it has shown the vulnerability of various species to subtle changes in their environment.
Biologists Ted Cooney and Loren B. Tuttle, for example, have confirmed expectations that zooplankton in the sound matures in April and May, growing to adults in less than 60 days and filling the upper water column with rich nutrients.
Salmon leave their freshwater streams and enter the sound for the first time during that same period, and it is the abundance of zooplankton that sustains them during their critical transition to life in the sea.
Cooney and Mark Willette of the state Department of Fish and Game also found that mortality rates for young salmon grow substantially if the fish fail to reach a certain size before the zooplankton fades. Undersized salmon fry are more likely to be consumed by larger fish. In a related study, other scientists at the center are studying an apparent switch in the diet of a chief salmon predator, the walleye pollock. Their research suggests that the pollock switch to salmon when the seasonal abundance of zooplankton declines.
If the zooplankton population was damaged by the oil spill, as many scientists believe, the pollock might have turned to salmon earlier than normal, attacking fish already weakened by inadequate supplies of zooplankton. That could explain the low salmon runs in the first couple of years after the spill.
Young salmon that elude the pollock begin feeding on herring, and there is some evidence that the huge “clouds” of herring that sustain much of the food chain were indirect victims of the oil spill.
“The herring population in the sound crashed in 1993,” Brenda Norcross, a fisheries biologist with the center, told a recent symposium in Fairbanks. The herring population remained depressed in 1994, although it was as robust as ever in other southeast Alaska areas. This year, it showed a slight rebound, although it is not near the level it was prior to 1993, Norcross says.
Scientists suspected the decline was related to the oil spill, but they were puzzled by why the impact should show up four years later.
It turns out that the herring were wiped out by a virus that is carried in an inactive state by most herring. The virus becomes active when the fish are under stress, and there is evidence that oil in the water can cause enough stress to trigger that, Norcross says.
Herring mature into adults in four years, she adds, so the herring that were supposed to return to the sound in 1993 were from the class of ’89, the year of the oil spill. The zooplankton population was still very low in 1992, she says, so the fish that returned were “in very poor condition.”
The virus broke out, she says, “and the population just succumbed to it. That’s our guess.”
Today, Prince William Sound is teeming with life, and to the casual visitor it appears as picture-perfect as ever. But an estimated 70% of the oil spilled from the Exxon Valdez is still in the area, buried by sediment on the beach and by the deep waters of the sound.
Scientists give it mixed reviews.
“I think it’s in recovery,” Norcross says, but Thomas is less sure.
“I dare not say anything like the sound has recovered from something that I personally believe we were never able to measure,” Thomas said. Until the herring return to full strength, “I wouldn’t say the sound is anywhere near as productive as it has been historically.”
The Prince William Sound Science Center has become part of a broader mosaic that could someday make the area one of the better-understood ecosystems on the planet. It has made Norcross a believer.
“The way we should do science isn’t off in our little corners at our little desks studying each of these topics,” she said.
“It’s for us to put our heads together in a multidisciplinarian level and form these ecosystem research groups that are looking at the big picture.
“It’s a lot more work, it’s a lot more communication and it’s a lot more pain in the neck for the individual scientists.”
But, she added, it is the only way to get the job done.