Marine Oil Spills: To Clean or Not To Clean?

A Conversation with Michael Foster

From the Environmental Review Newsletter Volume Three Number Four, April 1996


In March 1989, the oil tanker Exxon Valdez spilled over 10 million gallons of crude oil into Prince William Sound, Alaska. The spill was followed by massive clean-up using hot seawater at high pressure, as well as other mechanical and chemical means. In a paper published soon after the spill, Michael Foster, John Tarpley and Susan Dearn reviewed oil spill cleanup procedures used on shorelines and pointed out that some of these do more harm to the environment than the oil itself. In a later paper, Andrew De Vogelaere and Michael Foster examined the effects of the oil spill and clean-up on beach dwelling animals and plants: the 'rock weed' Fucus, barnacles, limpets, and snails. Fucus is a common brown alga that is the dominant organism on many of the rocky beaches in Prince William Sound, covering as much as eighty percent of the intertidal beach area. Eighteen months after the spill, Fucus cover on oiled and cleaned sites was less than one percent. Intense mechanical cleaning following the oil spill increased damage to the intertidal community and slowed its recovery. If reduction of environmental damage is the purpose of post-spill management decisions, in many cases intense mechanical cleaning should be avoided. Following is an interview with Michael Foster, one of the paper's authors.

     Michael Foster received the Ph.D. from the University of California in 1972 in biological sciences. He is a professor at San Jose State University, stationed at Moss Landing Marine Laboratories.  Professor Foster's main research interests are in intertidal and sub-tidal ecology, especially the ecology of marine plants. He has worked on kelp forests and rocky intertidal seaweed communities and has done scientific research on the effects of the Santa Barbara oil spill; for the EPA on the Exxon Valdez oil spill; and for the U.S. Minerals Management Service on an oil spill on the Pacific Coast of Washington State in 1989.

ER: Professor Foster, why did the cleanup of the Exxon Valdez spill become so controversial?

MF: The tanker Exxon Valdez was leaving Valdez, the terminus of the Alaska pipeline, to transport oil out of Prince William Sound when it ran aground and spilled roughly ten million gallons of Prudhoe Bay crude oil. In retrospect it was found that the spill response procedures that were supposedly in place for just such an accident were not in place. This lack of preparation on the part of the State of Alaska, the Federal Government and the oil companies created a public outrage.

     Everybody agrees that the best way to treat oil spills is to get the oil collected, burned, or dispersed, before it reaches shore. The oil spread and the more it spreads the harder it is to clean up and it was a massive amount of oil in a big area. People got out and did what they could, enlisting fishermen to skim oil off the surface. But given that amount of oil and that it could not be contained right away, the oil ended up on the shores. It drifted to the west along Prince William Sound, a beautiful, fairly pristine area ringed along the south side by numerous islands, and the oil came ashore as it moved. The spill eventually spread over 700 kilometers to the Kenai Peninsula.

     One of the problems in Prince William Sound was that a number of the islands have deep inlets and bays. The oil got in these areas where there is not a lot of wave action and it did not disperse or degrade rapidly after oiling a lot of shoreline. The initial effort was to collect the oil on the ocean, but that response was late. The next major worry was the salmon ranching facilities and spawning salmon going up the streams, so there was an effort to boom these off so at least the oil could not get into them. Then, after the main movement of oil through the Sound, the question was what to do about the oil that came ashore. There were certainly problems with navigation procedures that led to the spill, and poor preparation that contributed to its spread. However, I think some really wrong-headed decisions were made about what to do after the oil had arrived on the shoreline.

ER: During the spill, the cleanup was described as a circus. Why was there so much controversy about what to do?

MF: There were rocky shores, cobble beaches, sand beaches, estuarine habitats, and the open ocean. So there was a diversity of environments, and different cleanup procedures have been recommended for different environments. That makes decisions about cleanup complex. On top of that,many of these habitats were oiled over a large area. In addition, the number of different agencies and interest groups involved in the decisions has also increased over the years. So when you combine those three things, making decisions about cleanup after the spill occurs is very complex.

     In Alaska I think what happened, was that certain groups like the Alaska Department of Environmental Conservation (ADEC), which was the lead state environmental agency for the spill, took the position that every speck of oil had to be removed from the Sound. They may have done this because of a certain antagonism that seemed to arise between them and Exxon because they did not understand what happens to oil on shores, and also due to public pressure.  And I think as a result of that, a lot more cleaning was done than was ecologically advisable. As a marine ecologist I would prefer to see cleanup done in the best possible way for the environment rather than as a result of a political position, or the perceptions of the public for instance, that you should get every drop of it out of the environment.

ER: The idea is, if you make a mess you clean it up.

MF: That is part of it. The public is informed by the media, and the media most often reports what happens during the early stages of an oil spill: black stuff on the shore and dead animals. The impression is that this oil is extremely toxic, terrible stuff. The apparent best thing to do environmentally is to get it all out. And I think that perception and response is wrong.

       Way before the Alaska pipeline was built I was a reviewer of these issues for the Environmental Defense Fund. The Government was considering the oil company proposal to build a pipeline to Valdez and then tanker out of there; or to build a pipeline that went across Alaska and into Canada so the oil would never be transported by sea. Various predictions were made based on accidents per tanker load and, as I recall, it was predicted that for the Prince William Sound area there would be about one accident per thirteen years.

ER: Why is a crude oil spill not as toxic as a spill of refined oil products?

MF: In a crude oil spill a lot of the oil is composed of heavy molecular weight fractions like asphalts; it is gooey but not particularly toxic. If you have a crude oil spill on the ocean the oil floats on the surface and the majority of the lighter weight, more toxic compounds evaporate pretty quickly. Between twenty and forty percent of crude oil that gets spilled are relatively toxic fractions, most of which evaporate out into the atmosphere within a couple days. More refined products are specifically produced to increase these low molecular weight compounds because they combust better in an engine. If those products are spilled close to shore they are really bad. Gasoline spills are very toxic. If you have ever spilled gasoline on yourself you know it is not very pleasant.

     Most of my comments and experience are to do with crude oil spills. By the time crude oil gets to shore often what is left is this thick goo, a mixture of high molecular weight compounds and water, forming what is often called a mousse. Two main things happen: There are some low molecular weight fractions left and they can have effects on organisms. But probably more important is the smothering effect; essentially the organisms are covered. But in general, given that these intertidal organisms are washed by seawater once or twice a day, that mousse does not stick for long.      Originally I got involved in this in the Santa Barbara oil spill in 1969 when I was a graduate student. We ran out on the shore to see the effects of the spill because we were concerned about environmental damage and also effects on our research projects. I was quite surprised that in many places we went that were heavily oiled on one day, we would come back the next day after a couple of tides and the oil on the beach was much less. The main problem seemed to be with oil that got stranded up high on the shore where it dried. If the organisms are covered long enough, and if they are a filter feeder like a barnacle, obviously they are not going to be able to feed. Many of the seaweeds have mucous coverings and cuticles on them that seem to keep the oil from sticking very well. If the oil washes off in a few days most plants seem to do okay. The problem occurs where there is not much wave action and the oil sticks around. If you see rocks and cobbles on a shore it often indicates there is some wave action there that will stir the oil, resuspending it and keeping it from forming this smothering layer. Whereas large tide flats composed of sand or finer sediments are indicative of low wave action; oil is going to be sticking around there longer so it has a chance to penetrate the sediments, and the organisms are exposed to it longer. It is in these more protected, soft sediment environments where generally people think some cleanup is appropriate to do. The best response is to boom those estuaries and calm water places off, or to get the oil off the surface of the ocean before it gets there.

     The American Petroleum Institute convened a panel in the mid-1980s, before the Exxon Valdez oil spill, consisting of oil company people, oil cleanup experts and ecologists. They came up with an excellent set of recommendations based on studies of oil spills around the world ;habitat by habitat recommendations - about what should be done in response to an oil spill. On exposed coasts where the oil is coming and going and not causing a lot of damage although it looks terrible, the consensus was that maybe the best thing to do is nothing.

     There are many places in the world, California in particular, where oil naturally seeps to the surface. Numerous micro-organisms (fungi and bacteria) degrade oil. There are some nice studies done, particularly around the natural oil seeps off Santa Barbara, documenting some of the bacteria that biodegrade oil. So oil is not an absolutely foreign compound in the ecosystem; there are organisms there to degrade it. Wave action helps degrade it - water motion stirs it up and keeps nutrients supplied to these bacteria.

ER: It is not so much degrading the oil as dispersing and diluting it.

MF: It is both. Water motion disperses and mixes oil in the water, which increases the surface area and allows more bacterial action. Also, photochemical reactions from light break down oil. So there is a variety of mechanisms that can break down oil. And these biodegrading organisms have presumably evolved because oil is part of the environment. Of course in manmade circumstances the amounts released to the environment are very large in a short time.

ER: There is a difference between oil from a natural seep and a wrecked supertanker.

MF: I think the difference is the rate at which the organisms see the oil. So a reasonable concern would become, at these rates the natural processes of biodegredadation can be overwhelmed. That is especially the case in calm water. Whereas in more exposed, rocky intertidal situations they probably are overwhelmed temporarily, but because of the mixing and the dispersion, the oil seems to be degraded fairly rapidly. The Santa Barbara spill experience was really impressive to me. We went out and repeatedly visited sites for a month after the main amount of oil came on shore and I think everybody was impressed with how rapidly it disappeared.

ER: How big was that spill?

MF: The Santa Barbara spill was a well blowout; the worst of it lasted around ten days. It was on the order of seventy thousand barrels, about 3 million gallons.

ER: What about applying detergents to an oil spill to break it up?

MF: During the Santa Barbara oil spill, all of us who were trying to document the effects were influenced by the results of the Torrey Canyon spill which occurred in 1967. It turned out in that spill that cleanup was a disaster itself because of the massive amounts of chemical dispersants used. The chemicals used as dispersants at that time turned out to be more toxic than the oil itself. There were horror stories that came out later that cleanup crews were taking fifty gallon drums of these toxic dispersants and dumping them on the shore and into shallow subtidal areas - massive concentrated applications. So in 1969 everybody was worried about that and one good thing that came out of the Santa Barbara oil spill was that very few dispersants were used. There are now, however, new dispersant formulations. I am not an expert in this area by any means, but reviews I have read recently suggest these new dispersants are relatively non-toxic and work well. They don't work very well once the oil gets ashore when it gets into a thick layer, dispersants don't attack it very well but on the ocean surface they do work well. But I think people have been hesitant to use these new formulations because of the mind set that has held over from the Torrey Canyon.

          We noted in some early papers about the Santa Barbara spill that in the few places where this aggressive cleaning had been done, it had scoured the shoreline down to bare rock, and maybe that was bad. But we were too naive at that time to realize how bad it is. Some rocky shores we observed were on the beach in front of some expensive homes, and an effort was made to clean up those shores because of complaints by the homeowners. We visited a couple of these sites and noted that not only did this high-pressure hot water blast everything off the rock including the oil, but the oil ran back down and re-polluted the lower part of the shore.

     Much of the oil spill literature comes out in meetings sponsored by the American Petroleum Institute and most of the papers even now, but particularly back then, about oil cleanup had to do with how well the cleanup removed the oil. Very rarely did anybody ever look at the effects on the organisms. The thinking is that oil is very bad for the environment and it must be better to get the oil out of the environment regardless of the immediate effects on the organisms.

     When the Exxon Valdez oil spill came along, the agencies in charge had apparently not thought about those observations from other spills, and API recommendations well enough, and mechanical cleaning, this high pressure hot water approach, was not thoroughly evaluated relative to overall environmental consequences. Dispersants had a bad reputation, and the spill response was delayed so the oil got on shore. So the decision was made to make up these gigantic barges that suck up water and heat it and blow it out at high pressure. Environmental and other interest groups in Alaska, and the ADEC were breathing down the neck of the Coast Guard, the ultimate Federal decision maker, and Exxon to get the oil out. There was a very complex social, political, ecological mix of things that went on. I think  that under such circumstances, ecological considerations got elbowed aside.

ER: I can just see anti-environmentalists getting hold of this and saying, See, oil spills aren't so bad, it's just the cleanup that needs to be improved.

MF: I am not saying oil spills are harmless. They are something that certainly should be avoided ;they cause lots of damage, particularly to birds and mammals. But at least from what is known now, in terms of the immediate number of organisms killed and then long-term recovery, doing very little on rocky shores is ecologically sound. Going in at high tide and skimming up the oil and using fairly low-key mechanical procedures like scooping the oil out of tide pools would be reasonable; using fairly non-intrusive approaches or even leaving the oil in areas where there is some wave exposure causes much less damage than intensive cleaning of rock surfaces, and recovery is faster.

ER: You have been talking about crude oil spills. What is the scenario for a spill of a more refined oil product?

MF: There have been a couple of well-studied cases: The West Falmouth spill on the East Coast was widely reported because it occurred near Woods Hole Oceanographic Institute. That spill was diesel oil, and it got washed into an estuary during a period when there were fairly high winds and waves. The water was shallow and the wind mixed the oil fairly deeply into the sediments. The biologists and chemists traced the oil up through the food chain and documented a long-term persistence, over ten years. They concluded from this that oil spill effects can be long-term and oil can move through the food chain. There were not a lot of data on how populations changed but there was some reasonable evidence it was having an effect on the communities for a long time. I think however, that is the worst case, or nearly the worst case.

     A more typical scenario for coastal crude oil spills, such as the Amoco Cadiz, Exxon Valdez, and the Santa Barbara, is that after a year or so you are hard pressed to find any oil around unless you find it buried down in sediments that got layered on the beach. You see few long-term toxic consequences. It is not like a Love Canal. The material is dispersed and biodegrades fairly rapidly and it is not particularly toxic to start with, so these long-term phenomena that we associate with Superfund sites do not usually occur with oil.

     After a few years, in areas where the oil either gets buried or leaches out into the sediment, you may dig down and find a layer of oil. We dug down five to six feet on Santa Barbara beaches two to three years after the spill and found a layer of tar in some areas. But most of the organisms are in the upper layers and it didn't seem to be having a big effect.

     The other place you see oil persisting for a while is on high intertidal rocks where it was cast up during a storm or due to high tides. Apparently the water did not return quickly enough and the oil dried to form an asphalt-like deposit. In that case it is covering the surface and organisms don't settle on it as well as they do on rock, but it is pretty much an inert asphalt sitting there. In the Exxon Valdez spill we tagged some of these patches of tar and observed them over time. Most of the patches were gone within a year. So at least in that circumstance, in terms of taking up space and inhibiting recruitment, the phenomenon only lasted about a year.

ER: What do you mean by inhibiting recruitment? How does an ecosystem recover from an oiling?

MF: On rocky intertidal shores the large plants and many animals are sessile: such as, seaweeds, and barnacles, and mussels. They and many mobile animals have spores or larvae that are released or develop in the water as plankton. These eventually come out of the plankton, settle on the substrate, and grow up into adults. Oil can kill the larvae in the water, but again that is caused by toxic fractions that are short-lived. When the larvae or spores reach shore and settle down and attach, tar on the rocks might produce a substrate that is not suitable for attachment, either because it is toxic or probably because it is too warm or doesn't have the right surface texture.

ER: Maybe they avoid it in the first place?

MF: That could be as well. I don't know anybody who has done those kind of experiments. My overall point is, we are talking a year or maybe a bit longer when this may occur before the tar degrades.

ER:  Where do these spores and larvae come from?

MF: They come from other adults in the area. Many of the seaweeds and some of the animals do not seem to disperse very far; whereas other organisms' development occurs in the plankton and they can disperse long distances. But let's say just for the sake of argument that thirty or forty percent of the species on a shore have fairly localized dispersal. If the adult populations are removed so there are few local adults nearby to produce recruits, then the area is going to recover more slowly than if there were more adults around.

     Species in which the larvae or spores do not go very far are reliant on local populations to replenish them, at least in the short term. Fucus, this brown alga called a rock weed that dominates most of the rocky shore in Prince William Sound covering the high all the way down to the mid-shore is probably a fairly short distance disperser. And so if you come in and blast it all off the rocks, recovery is going to take longer, whereas if there are some adults left around that can replenish locally, then presumably recovery would be faster. The oil itself certainly killed some Fucus plants, but typically on oiled shores there would be plants left that contribute recruits. But if you remove everything during cleanup, that repopulation is going to take much longer.

ER: Are there follow-up studies being done to further assess the damage from the cleanup?

MF: These have occasionally been done on aspects of other spills. As far as I know some studies were done in Prince William Sound but I have not seen results in the literature yet. Communication of information during and after the spill was severely inhibited by concern over lawsuits. You would think that people would be out there doing experiments, or when a spill happens it could be used to better test these ideas and so provide better information to use in decisions concerning future spills. We suggested doing that during the Alaska oil spill and got nowhere.

     Oil spills create a short-term crisis atmosphere. After the immediate response, attention and support commonly shift to lawsuits and creating more regulations and regulatory agencies. The best thing would be to use spills as experiments. This is entirely possible if organized quickly. At various times we have also proposed actually doing some small scale oiling experiments that involve purposely oiling some areas. Some might bristle at this - some organisms would be killed in the process of doing such experiments. But the end result would be procedures that might save millions of organisms when an oil spill occurs.

ER: What about animal rescue efforts?

MF: The cost of sea otter recovery and cleaning efforts in Alaska, when we published the article on cleanup in 1990 was over $25,000 per otter; but that has gone up, the latest estimate is $80,000 to $100,000 per otter that survived. I can appreciate the feelings people have about these animals and that they want to help them. But from an ecological point of view, it seems to me that unless the population is endangered or at least in bad shape, that these kinds efforts are a waste of money. They do make people feel better that they are doing something but one would like to see that kind of money going into cleanup studies or buying habitat for conservation, or doing other things that actually benefit the environment.

     We estimated that 15,000 birds were killed in the Santa Barbara oil spill. Estimates for the Exxon Valdez are over 100,000. A review done by the Congressional Research Service points out that during one duck season in Maryland there are approximately 300,000 ducks shot. I empathize with the fishermen not being able to fish during an oil spill. Moreover, because of the public perception of oil, even if the fish are not tainted during a spill, the fish buyers won't buy them if they know the fish comes from Alaska. But on the other hand, fishermen kill many more millions of fish per year than have ever been documented being damaged in an oil spill. Fish populations world-wide are in severe decline from overfishing. The Grand Banks are only the latest example; people seem to get more upset about an oil spill. To my mind, other things that humans do have a much greater effect on the environment than oil spills. I think a lot of this is psychological; you see these pictures of the shore covered with gooey oil, and it stinks, and you see these poor birds and it is hard not to think that this is really an environmental disaster.

     A solution to problems with decisions in a crisis atmosphere - when you have very little time to make reasoned decisions, is to set up response groups before a spill in areas where spills are likely: here are the habitats, here are the data, let's come up with an environmentally sound response plan and stick to it when a spill occurs. Have all the agencies agree to a plan in advance. Then you have something in place and are prepared. When special interest groups or misguided agencies start yelling, Get the oil out, one can say look, we have a sound plan here. During the spill you would need some fairly powerful people in charge that will not give in to that kind of pressure.

ER: Wasn't that the idea by making the Coast Guard the lead agency?

MF: Presumably, but apparently they did not have the expertise, preplanning, or power to lead better on environmental effects of cleanup. Exxon by the way was pushing not to do so much cleanup. In terms of cleanup, Exxon was not the bad guy. They funded it and they put together much of the cleanup response, but they did not want to clean in many areas. There was tremendous public and agency pressure even two and three years afterwards to go out and scour the beaches once again and get all oil off them. The motivation for this among some agencies was not clear to me, but the result indicates that damage to the natural environment was not first on their list of concerns.


Copyright 1996 Environmental Review