MS. DIANE REHMThanks for joining us. I'm Diane Rehm. A new study says that petroleum-eating microbes had significantly reduced a huge oil plume from the BP spill. This seems to contradict a study published last week which reported the existence of the huge plume and that bacteria was consuming the oil, but at a slow pace. Joining me in the studio to talk about the papers, both of which were published online by the Journal of Science, Juliet Eilperin of the Washington Post, Ronald Atlas of the American Society for Microbiology and David Guggenheim of 1planet1ocean. And throughout the hour, we'll take your calls, 800-433-8850. Send us your email to drshow@wamu.org. You can join us on Facebook or send us a tweet.

MS. DIANE REHMFirst, before I talk to my guests here in the studio, I'm going to chat with each of the two scientists. Terry Hazen is head of the ecology department and senior scientist at the Lawrence Berkeley National Laboratory in California. After that, I'll chat with Richard Camilli. He is associate scientist at Applied Ocean Physics & Engineering at the Woods Hole Oceanographic Institution. So first of all to Terry Hazen, good morning to you, sir.

DR. TERRY HAZENGood morning.

REHMTerry, summarize your findings for us, please.

HAZENWell, what we did was to start looking for microbes that were within the plume and outside of the plume, trying to characterize the microbial community that was there to see if there were differences. And there were microorganisms that could degrade the oil. And we used a variety of molecular techniques, direct isolation, and then we also -- of course, we're measuring the oil concentrations and potential nutrients and that sort of thing.

REHMSo how did you take your samples? And what were your conclusions?

HAZENSo we filtered large amounts of water and then froze those filters and brought them back to the laboratory and extracted them for DNA, RNA, proteins and lipids and then did several different assays using our PhyloChip to see, in fact, what species were there, and the GeoChip, which is a functional gene array, and then also a lipid analysis. We are -- also took some of that and are currently doing a metagenome sequencing with the Joint Genome Institute. Now, we also took samples back to the laboratory that were live and then also took samples back that we had fixed in the field for various chemical assays.

REHMOkay. Here is what I want to understand. Is it clear, in your mind, that these bacteria are consuming the oil plume?

HAZENAbsolutely because they are -- we found that basically, they go from a higher density, and they've actually -- the dominant ones that are in the plume have genes that actually we can link to particular oil components, particular hydrocarbons, and see that the frequency of those genes actually goes up. We also have taken them back to the laboratory and put oil into water that didn't come from the plume at the same depths and basically got those -- the same results where the bugs would grow up and dominate and degrade the oil.

REHMYour study, I gather, seems to be in opposition to the study by a team from Woods Hole that was published last week. They say that the plume has either simply degraded or moved on, and it's being consumed in much smaller amounts by the bacteria. How do you respond to that?

HAZENWell, there's a combination of things going on, both biodegradation and mixing. And the concentration of the oil in this particular plume, as Rich Camilli's group showed, is very low, and we found the same thing. We've -- I think, basically the papers are complementary. And I've talked to Richard about this. They were measuring different things. And, of course, they were making assumptions based upon small amounts of oxygen depression. And we actually did a lot of other measurements in terms of nutrients and direct measurements of the microbes themselves.

REHMAll right. And finally, I gather your research was partially funded by BP. Is this causing questions to be asked about your study?

HAZENWell, I've been asked about this. It does. BP funds this through the Energy Biosciences Institute, which has a $500 million grant that was given to the University of California in cooperation with Lawrence Berkeley National Laboratory and University of Illinois about four years ago. And we have a program that started a year ago last January on Microbial Enhanced Hydrocarbon Recovery or oil recovery, and -- which John Coates and Bruce Fouke and I lead. And that program is looking at the same sorts of things with microbes so...

REHMAll right. All right. Terry Hazen. He is head of the ecology department, senior scientist at the Lawrence Berkeley National Laboratory in California. Thank you so much for joining us.

HAZENYou're welcome.

REHMAnd now, joining us by phone from his office at Woods Hole Oceanographic Institution is Richard Camilli. He is chief scientist for a research team that first mapped the underwater plume. Good morning to you, sir.

DR. RICHARD CAMILLIGood morning, Diane.

REHMTerry Hazen said that his study and your study are complementary, and yet you seemed to have reached rather different conclusions. How would you characterize the two studies?

CAMILLII would agree with Terry there. Our studies were somewhat complementary in that they differ in their respective range and scope. Our goals were to --first of all, I'd ascertain if the subsurface plumes of hydrocarbons did exist. And if so, then to try and characterize them in terms of where they were in their spatial extent, how they are created, if they were linked to the well or not because there were questions of natural seeps and then describe the rate of motion of these plumes in the water column and where they were headed.

REHMSo what is your explanation on how or whether the plume has actually disappeared?

CAMILLII would caution not to use the term disappear. As scientists, we require evidence, and so there are characteristic tell-tales as to how the plume either gets dispersed as this sort of an abiotic process or gets degraded by the microbes. And so the -- a part that may have created a little bit of confusion here is the nuance in terms of how we describe the microbial degradation. We were using what was an apparent oxygen demand, looking at the oxygen drawdown within the plume and, basically, if you have aerobic respiration occurring by the microbes, taking oxygen and using it to biodegrade the hydrocarbons -- as a rule of thumb you need roughly three parts oxygen for every two parts of carbon.

CAMILLINow, the reason that we were interested into that apparent oxygen demand is because there were -- there was a lot of speculation that there would be these hypoxic events that would lead to dead zones that might threaten fisheries. And that's really important for the fishermen and shrimpers down there in the Gulf to know if this was going to be a problem.

REHMAll right. Well, one final question. And do you believe that these petroleum-eating microbes are responsible for -- if you don't want to use the word disappearance, use the word reduction -- in the manifestation of the plume itself?

CAMILLIAbsolutely. The microbes -- it's well-characterized in the scientific literature that microbes do degrade hydrocarbons. They do it in the water column. Sometimes they even do them within the reservoirs themselves deep inside the Earth, so I have no doubt that microbial degradation is occurring. But there are certain tell-tale indicators that we can use to reconstruct what is going on in terms of the rate of microbial degradation. The apparent oxygen demand is one. There's also a preferential degradation that occurs where certain types of hydrocarbons are more susceptible to degradation than others. And then there's also an isotopic shift that you should see within the hydrocarbons themselves.

REHMAll right. We'll have to leave it at that. Richard Camilli of the Woods Hole Oceanographic Institution. Short break. Right back.

REHMWelcome back. And having talked with the two scientists who recently issued reports in Science Magazine online, Terry Hazen, Richard Camilli, we turn now to our guests in studio. Juliet Eilperin, she's environmental reporter for The Washington Post. Ronald Atlas, he is a microbiologist at the University of Louisville, past president of the American Society for Microbiology. And David Guggenheim, he's president of 1planet1ocean, a project of the Ocean Foundation where he is a senior fellow. Do join as at 1-800-433-8850. Juliet Eilperin, can you explain for us the difference between these two studies that we've just heard about and why one seemed to say so blatantly the plume is gone -- it's been eaten by oil-consuming bacteria -- the other seemed far more nuanced?

MS. JULIET EILPERINRight. So one thing that's a clear difference between these studies -- and, of course, Ron can probably elaborate on this -- but -- is that the Woods Hole, the earlier study that Dr. Camilli did, was -- again, as he indicated -- using oxygen depletion as a measurement of how quickly the microbes were degrading the oil. And those scientists concluded that this was not happening rapidly because there had not been the level of oxygen depletion one would see if they had been degrading it quite quickly. Now, the second study that Dr. Hazen headed up clearly showed or found that there was a rapid depletion of the oil through microbes, particularly a newly discovered species that these scientists said were degrading the oil more rapidly than had been previously thought.

REHMBut the basic question, it seems to me, Ronald Atlas, is the existence of the plume. Is it there? Is it not there, and if it is there, to what extent?

MR. RONALD ATLASBoth these studies were actually done in June. And at that time, both scientists were finding a plume. They were finding the plume. They were studying the plume. They reached somewhat different conclusions. Hazen has gone out more recently and reported this week at a meeting in Seattle that in the last few weeks, he can no longer find the plume. I've not heard Camilli back out at sea looking for it. So the question really is what's happening today? It could be that they're just going to the wrong place, that the plume has moved and it's hard to find. That's where Camilli is right, that science still has to look further. On the other hand, Hazen may be right that the microbes and the dissipation have moved on. What we've got to realize is science is an ongoing event. This is a study in progress, and the next weeks or months will tell the tale.

REHMDavid Guggenheim, how do you see it?

MR. DAVID GUGGENHEIMWell, I agree with what we heard from Ron that the ocean is an incredibly dynamic place. And satellites have revolutionized the way we can look at the surface of the ocean. But when we're looking at sampling underwater, we're still using ships which barely go faster than bicycles and dropping in point samples at discreet locations. And it's very hard to paint a coherent picture from that. And the risk here is that we extrapolate what we're hearing too far to say either the plume is there or it's gone. We have to recognize there's tremendous uncertainty left in this question.

REHMAre there other studies supporting either of these two perspectives, Ronald Atlas?

ATLASI think we're going on. I mean, Hazen is going back out in the next weeks...

REHMOkay.

ATLAS...with more studies. Others are going to be on ships and eventually we'll know what has happened to the oil. We'll get much better estimates.

REHMWhat about the marine life, David Guggenheim?

GUGGENHEIMWell, this is one of the key questions that we have, is that this decision to leave most of this oil in the ecosystem for Mother Nature to clean up was explained as a tradeoff -- tradeoff, presumably by the use of chemical dispersants to spare the coastlines and the marshlands, but at what cost? And it seems that we don't know what that cost really is. This is a tradeoff where one side of the equation is a -- well, actually both sides of the equation are really unknown. We don't know whether by dispersing this oil we have facilitated its uptake into the food chain. And some of the causes -- or some of the -- excuse me, some of the problems may not be visible to us for months or years from now as some of these compounds accumulate in the tissues of corals and sponges, algae, fish and so on.

REHMWhat about the long-term effects, Juliet?

EILPERINWell, you could have tons of effects, particularly on the youngest and most vulnerable aspects of sea life, the larvae of, say, the bluefin tuna -- incredible species that is already under intense pressure.

REHMWhy are clams so vulnerable?

EILPERINClams, I think, because they bioaccumulate the contamination and oysters. I mean, certainly that's one of the reasons you've seen, for example, the decisions by federal authorities to say shrimp, you know, is acceptable to eat in a way that some of these bivalves are not because they...

REHMBut shrimp are bottom feeders, are they not?

GUGGENHEIMTrue.

REHMLobsters, bottom feeders?

GUGGENHEIMBut what these bivalves do is they have built-in filters and pumps, basically. So they are constantly filtering that water and processing quite a large volume of water. So they're a good sentinel species or indicator species if there are problems of toxics in the water. And that's why when there's an outbreak of red tide or something like that, we're always concerned about the shellfish because they're the first ones to have those sorts of concentrations.

REHMAnd what concerns have been raised as yet from the fishermen themselves, Juliet?

EILPERINWell, they're very concerned even -- you know, it's interesting. When shrimping season reopened recently in Louisiana, and you really had a split where some fishermen decided to go out again and participate, and others chose to stay home because they felt like there wasn't enough science there to let them know that the seafood was safe. And what they particularly were worried about is if you did have Americans or others get sick from the seafood that they ate from the Gulf, the long-term commercial and market implications of that would be devastating for the industry. And so they were a little worried it would be too soon.

REHMSo right now we got an egg problem, and later on -- or even now, we could be facing a fish problem. One thing I want to go back to, Ron Atlas, is the notion that this bacteria that has been consuming the oil apparently is a species we've not seen before. Is that correct?

ATLASIt's related to other species we have seen before. And so it's not really that novel. It's -- we have hundreds of different bacteria that are known to consume oil. This is -- oil that enters the environment does so naturally for many seeps, and so bacteria have evolved the capability of degrading oil. To them, it's a food source. It's a way of gaining energy and carbon from the environment. And so it's really nothing new that bacteria consume oil. That is a known.

REHMOkay.

ATLASThe question here is, a plume, subsea, cold water, how fast is it occurring?

REHMAnd the other question for me, I must say, is how the media played this when it first occurred. We heard the plume is gone. The bacteria have consumed the plume. Well, as you've all suggested, there could be other plumes that could move elsewhere. Even Dr. Hazen has not said all the plumes are gone. Juliet.

EILPERINI think this is something that the media struggled with. Obviously, we've tried to be nuanced about it, particularly when you -- but when you have one study that comes out one week, and another a week later, I mean, it really does leave journalists -- many of whom are not experts, particularly in this -- you know, we don't spend most of our days writing about microbes. And so I think that that is a real challenge, and it's a challenge that you often see in science which is policymakers and the public really would like definitive information, often on a more rapid time scale than scientists can produce.

REHMTough to get. David Guggenheim.

GUGGENHEIMAbsolutely. I think some of this was triggered by the administration's August 4 release of its oil budget report where Carol Browner, whom I have great respect for, got on "The Today Show" and basically said 75 percent of the oil is gone. And that's what led to a rapid fire number of articles in the media talking about this issue, and I think that invited a lot of this controversy. Because as you look at that report, if you listen to the hearings that took place here at the House subcommittee meetings last week, you realize, no, 75 percent of the oil is not gone. Maybe 90 percent of the oil is still in the Gulf of Mexico.

REHMBut why then are reports saying 75 percent is gone?

ATLASWell, I'd accept that 75 percent may well be gone. What I'm surprised with the media is they haven't then said that that means twice as much oil as the Exxon Valdez spill that's still left at the environment. That 75 percent still leaves you with a lot of oil out there potentially.

EILPERINI have to just pipe up and defend the media there. I think we have really said that this is a tremendous amount of oil in the natural environment, and we have really tried to convey that. So I don’t think that that -- you know, again I think part of the issue is just when people hear 75 percent versus 25 percent, it leads to certain conclusions. But you know, again, these things are very hard to gauge particularly when you're talking about the long-term impacts.

REHMYou had a very large piece in The Washington Post yesterday on the Minerals Management Service. What did you discover about why they failed when it came to this particular oil spill?

EILPERINI think there are a couple of different things, but the fundamental issue is that over time, the agency made the decision that it was essentially in a partnership with the oil and gas industry in large part because its central mission was to fulfill the nation's energy needs. And that was going to be done through leasing and so curbs on that -- whether it was through environmental studies or tough enforcement came in second place -- and really, they found themselves in a partnership, but a partnership in which the federal government was not an equal and was actually below industry in terms of making key decisions on regulations and how to proceed. And that's really where they delegated responsibility. And I think what you're going to see in the coming months, prodded both by Congress and the administration, is the new agency that's replaced MMS, reasserting its authority over offshore oil and gas drilling.

REHMAnd under brand-new leadership and tougher regulations, I would presume.

EILPERINAbsolutely. Michael Bromwich, who has no background in this kind of matters but has a long background in terms of cleaning up troubled agencies and government institutions, is overseeing the reorganization that's going on. Now, you're -- obviously there's legislation that already has passed the House that's pending in the Senate that's going to reshape it. And again, there are many commissions and groups investigating this that are probably going to provide more regulatory reform proposals.

REHMJuliet Elperin, environmental reporter for The Washington Post. And you're listening to "The Diane Rehm Show." We have a number of callers. We'll open the phones now first to Norman, Okla. Good morning, Ed. You're on the air.

EDGood morning, folks. How are you today?

REHMFine, thanks.

EDMy grandmother had a small hobby farm here in central Oklahoma. Some years ago, she -- well, she had several oil leases on the property, and she had an oil leak on the property which damaged a handful of acres. It took a little bit of time, but amazingly enough, it recovered very quickly. The Gulf of Mexico is an amazingly dynamic resource in the world's habitat and wildlife wise, and we may not fully understand what's going to clean up this atmosphere. However, I think it's going to recover in an amazingly quick capacity.

REHMDo you agree with that, David?

GUGGENHEIMWell, I think we really don't know the answer to that. We call the Gulf of Mexico resilient, and we call Mother Nature resilient. And time and time again, we do something bad, and she does her magic and does appear to recover. But we don't know where the so-called tipping point is. And my colleague and friend Ian MacDonald from Florida State University, in his testimony last week, talked about the fact that sometimes, it's not this big spectacular catastrophe -- the visible birds being full of oil or dolphins or whatever. It's things happening at a much more subtle scale that can disrupt ecosystems and their ability to persist so -- especially with the oceans where we are limited in our ability to see what's really going on from the surface. Even a dead ocean can look beautiful. So the concern is will this lead to undermining the very fabric of that ecosystem which is all about relations among different...

REHMOf course.

GUGGENHEIM...different animals and critters?

REHMAll right. To David in Tallahassee, Fla., you're on the air.

DAVIDYes. I understand that there is natural seepage of oil from the sea floor, and microbes have evolved over time to use that oil as nutrition. Now, BP dropped chemical dispersants into the gulf, and, of course, microbes have not evolved means of consuming the combination of the oil and the dispersant chemicals. Wouldn't that inhibit microbial consumption of the oil? And wasn't that a bad idea to drop the chemical dispersants?

REHMRonald Atlas.

ATLASNo. Actually from a microbial point of view, it was a good thing to do. Microbes do much better when oil droplets are dispersed, and they're smaller. Many studies have shown faster rates of degradation when you add dispersants to oil. Now, admittedly, this is the first time on this scale we've seen this sort of event, and that again will be subject to study. But everything we've known before suggested that unlike -- maybe toxicity to higher organisms where we are concerned about dispersants, the microbes do better.

REHMJuliet.

EILPERINYeah, and I think if you look at the head of the National Oceanic and Atmospheric Administration, Jane Lubchenco just testified yesterday before the presidential oil spill commission that at this point, the oil droplets are dilute. They're -- she described it as on a microscopic scale about the width of a human hair and said that while dilute doesn't mean benign, they're certainly broken up. And I think also in the skits to David's earlier point that, you know, there was this decision that was made, and it was largely a political decision that it made so much -- that there was so much pressure to keep the oil of the marshlands and off the beaches, that they wanted to focus their efforts on trying to disperse it in the ocean even though that was somewhat of an unknown because there was so much pushback from local authorities, local residents about the idea of the oil coming ashore.

REHMTo what extent are you concerned about dispersants, David?

GUGGENHEIMWell, I'm very concerned. And when I was in Louisiana last month, the fishermen there are extremely concerned because they can't see this oil, and they don't know whether they're going to have a business anymore.

REHMDavid Guggenheim, he is president of 1planet1ocean. We'll take a short break. More of your calls, your email, when we come back.

REHMAnd as we talk about what's left in the Gulf, what the long and short-term outlook may be, here's a Facebook comment from Steve asking, "Is anyone doing research in the ways of fostering the growth of these bacteria to help mitigate future oil spills, perhaps an inoculation or ways of introducing oxygen into the water column?" Ronald Atlas.

ATLASI've been working on bioremediation as a field for cleaning up oil spills for 40 years. We certainly used it in the Exxon Valdez spill. But it doesn't involve normally adding bacteria or Inoculaid. There are naturally-occurring bacteria there. They are, as Terry Hazen has shown, colonizing the oil, growing on the oil, and adding bacteria is not going to be of much use.

ATLASThe only places though where we've really seen benefit from things like adding nutrients as fertilizers to help these bacteria is along shorelines. We've never been able to do that in an open ocean where they would be diluted away and where, in the past, we've not documented the sort of effects on biota that we're worried about in this particular spill.

REHMI see. David, any comment?

GUGGENHEIMJust more of a philosophical comment that the frustration here is that many of these discussions and questions, we should have been having decades ago. And admittedly, some of those discussions did happen. Ron told me earlier about some of them that occurred in the '70s and '80s, but never discussions in depth about what to do for a spill a mile below the surface because we bought in to the line from the oil companies that this could...

REHMThat they would say...

GUGGENHEIM...never happen.

REHM...that it wasn't going to happen.

GUGGENHEIMAnd worst case scenario was not the worst case scenario.

REHMHere is an email from Sue who says, "What happens to the oil consumed by the bacteria? Do the bacteria break down the oil, and if so, into what?"

ATLASThey do break down the oil -- ultimately, the carbon dioxide and water. They also make protein, new bacterial cells. In fact, in the '60s, before BP was dealing with the spill, it was building large fermenters to grow bacteria on oil with the idea that you and I, for lunch today, would be eating bacteria, not whatever else we're going to eat. They were going to make protein from growing bacteria on oil. And the world's largest fermenters were built in Russia and China to do just that by BP.

REHMI'm astonished.

ATLASYou're not ready to eat bacteria...

REHMNo, I'm not.

ATLAS...for lunch. I can see that.

REHMI mean...

GUGGENHEIMI've lost my appetite.

REHM...I may be already consuming certain types of bacteria which are in the gut, which my body has grown accustomed to, but you're talking about introducing a new kind of bacteria.

ATLASThat's what they were thinking about in the '60s. And they weren't foolish enough to think you would like slimy bacteria. They had introduced contracts with Hershey's and Nestle's to make chocolate-covered bacteria.

REHMWow. That's quite a statement. Let's go now to Jim in Brighton, Mich. Good morning, you're on the air.

JIMHi, Diane.

REHMHi there.

JIMI'm a veteran chemist and an Air Force officer at materials lab, and I've got a lot of patents and inventions. And for 50 years, I've been involved in chemistry and everything. And I -- my initial take was what a disaster it was that BP decided to hide the oil by spraying the COREXIT dispersant on the oil and allowing it to submerge in a milky way below the surface. And my solution was so simple. It was to take up fume silica made by Cabot Corporation, that if you just sprinkle it on top the oil, it clumps up. And I was picking it up with the kitty litter scoop, you know, out of the water, and the water was clear. And Kevin Costner, he's got these skimmers that would have allowed BP to skim the oil as it was surfacing onto freighters. You could take that to an electric company and burn it, and then take the ash and recycle it.

REHMI'm sure you have all heard many suggestions. Kevin Costner actually testified before Congress, did he not, Juliet?

EILPERINHe did. He did. He has his business, and so he was arguing that that was the way to (unintelligible).

REHMWhat do you think, Ronald?

ATLASI mean, we've had so many solutions thrown, and everybody thinks it will work. The trouble is when you're in the field, in the real oil spill with oceans and waves, and a lot of these things simply don't work.

REHMBut you're as concerned as Jim is about the effect of these dispersants, David.

GUGGENHEIMExactly. And when the decision was made to use those dispersants underwater, the decision ultimately meant that that was oil that would never be recovered. That was oil we were asking Mother Nature to deal with because it could not come to the surface, and BP no longer had a responsibility to clean it up. So it's -- makes sense that we all were very suspicious since there were no compelling reasons to disperse at the source, except the only rational explanation I've heard is to protect workers on the rig from the fumes from -- or on the ships above to protect them from the oil bubbling up and the fumes and toxic effects.

REHMAll right. We have an email from Eric in Cincinnati. "Do we know if there is a depth at which microbes do not exist?" Ronald.

ATLASNo. They exist throughout the water comb and down into the sediments, and clearly this plume, at depth, has lots of bacteria now growing on it.

REHMAll right. To follow up on that, from Jean, "Will the same microbes eat the oil that hides 6 inches below ground level in beaches and wetlands?"

ATLASWe're going to see different bacteria in each case. What we've seen this weekend, studies reported in Seattle, were that different bacteria were involved in degradation in the mosses, in the sands of some of the Florida beaches and in the plume that Terry Hazen was studying.

REHMAll right. To Martinsburg, W.Va. Hi there, David.

DAVIDHello, Diane. How are you doing?

REHMFine, thanks.

DAVIDMy question is -- and I don't remember the name of it. I remember it began with an I. The -- now, the second worst oil catastrophe in the Gulf. Another rig had -- basically, the pipe had been fractured loose, pumping oil. And one of the things I've read was that this one, they were dumping detergents into the oil which was actually keeping it away from the sun, which wasn't breaking it down, and it was actually poisoning some of the microbes. And that was on -- from Discovery. But I was wondering why they're allowing Mother Nature to do more than we're, you know, trying to fix it and ended up, basically failing in each attempt?

REHMWhat do you think, Juliet?

EILPERINWell, he's referring to the Ixtoc spill that occurred in the Gulf but on the Mexican side, and Mexican authorities dealt with that. I'm not familiar with this phenomenon that he's talking about, so I'm not sure. But again, I think as we're discussing, we are, frankly, relying on nature to address a lot of the spill.

REHMTo a great extent.

EILPERINAnd one thing that I just also thought was a good point that I wanted to make is that your, you know, the caller before him mentioned the idea of -- that it was BP's decision. Certainly BP was pushing for the widespread use of dispersants, but the federal government signed off on it. It was ultimately a joint decision which was approved by the Obama administration. So, I think, just in fairness, it's worth saying that our government made this decision as well as the responsible party of this bill.

REHMAnd go ahead, Ronald.

ATLASYou know, while it's true that it was a political decision jointly made by BP and the government to use dispersant, it's also true that in prior spills the real impacts have been on shorelines. And so keeping the oil away from the shorelines where birds nest, out of the marshes, had the potential for saving a lot of the populations that in prior spills were severely impacted. What that has meant -- as David points out though -- is we've entered into an unknown world of what's happening to oil that's dispersed widely. Subsurface, where is it going? Is it going to harm something else? Is it just going to disperse, and we'll never detect any effect? Those are the unknowns for the future months and years of scientific study.

REHMTo Norwalk, Conn. Good morning, Dave. You're on the air.

DAVEGood morning. Thanks for the call. A few minutes ago, you talked about how the -- when the microbes do eat the oil, it breaks it down into, I think you say, carbon dioxide and water?

ATLASThat's correct.

DAVEWhat's -- so then what is the concern of having the oil then in the food chain? It sounds like the oil then is not oil anymore.

ATLASThe oil is not oil anymore when microbes break it down. They make protein. That's normal protein that enters the food chain. The problem would be if oil was not degraded, and it remained and it entered into a clam or a shrimp or something else.

REHMDavid.

GUGGENHEIMThat's right. And what we heard from the scientist earlier is that -- and I think we all agreed -- is that these microbes are consuming the oil, but not...

REHMIt's the extent to which they are (unintelligible).

GUGGENHEIMExactly. They have not consumed all of the oil necessarily, and we have seen observations by other scientific teams in the last couple of weeks of oil droplets and particles depositing on the bottom. And we know that there are deepwater corals in the Gulf of Mexico and all sorts of other benthic organisms -- those that live on the bottom -- that could be ingesting this oil and allowing those toxins to enter the food chain.

REHMDoes that answer it, Dave?

DAVEYes. So in other words, if the animals -- they eat the microbes, the oil isn't going into that food chain. It's going into the filter feeders and things like that?

ATLASYeah, the microbes are not the source of entering oil into the food chain. They're removing it.

DAVEAll right. Thank you.

REHMAll right. Thanks for calling. To Miami, Fla. Good morning, Edward.

EDWARDGood morning, Diane. How are you?

REHMI'm fine. Thanks, sir.

EDWARDThank you. I just wanted to clarify something in my mind 'cause I deal with microbial contamination in fuels. And it's a pretty common event on land-based tanks. And generally, the process that I've been aware of is that organisms, when they degrade the fuel, they don't actually consume it like you and I would think of consumption of food item. But what they do is they oxidize that fuel in an aerobic scenario, and they'll take that alkane or the cyclic molecule, and they'll oxidize it from a hydrocarbon to an alcohol to an acid and to carboxylic acid, by which they do another reaction.

EDWARDAnd so they get two fragments. So I guess what I'm trying to understand is that how long does your panel think this process is going to take? Because I understand they hadn't checked the dispersants, and that made sense where dispersing is diffusing the oil into a more of a dilution effect with the ocean. But I would still think that it's going to take a while for those microbes to really break this fuel down into its basic components.

REHMI think Edward has asked the $64 billion question.

GUGGENHEIMWell, I agree. I actually think that's a better question for Ron to get at 'cause that's such an expensive question. I'm not going to...

ATLASI mean, we've never seen an instantaneous degradation of oil. It takes weeks or months normally...

REHMOr years?

ATLAS...or even years.

GUGGENHEIMYeah.

ATLASHazen's report said the half-life was less than a week, which does not mean all of the oil goes away in less than a week. It means half of it goes away, then the next week another half, and the week after that, another half. But it doesn't mean absolute disappearance of all the oil.

REHMSo does anybody have any predictions based on how much oil has already entered the Gulf as to how long this could take? No.

GUGGENHEIMI think that's the point.

REHMI think that's -- yeah.

GUGGENHEIMIs that we are in an uncharted waters here, and we need to encourage everybody to be very careful about broad, sweeping statements and predictions.

REHMThanks for calling, Edward. And you’re listening to "The Diane Rehm Show." And let's now go to Hanover, N.H. Good morning, Edward.

EDWARDAll right, good morning. And thanks for taking my call.

REHMIndeed. Go right ahead, sir.

EDWARDIn 1980, Ananda Chakrabarty, working at GE, patented an oil-eating bacteria, but GE refused to apply it for, I believe, medical reasons, fearing that the plasmids would be transferred to pathogenic bacteria. Is there any chance that these bacteria could evolve such an appetite that they would actually enter oil wells and consume oil from the well?

REHMInteresting.

ATLASNow, the environment in the oil well, it's quite different. And there's not enough water there to help support the growth of the bacterias. They certainly do grow on the surfaces of some of the reservoirs, and they degrade some of that oil, which no longer is valuable. But no, we're not in danger of consuming the world's oil, although we've heard that sort of "Andromeda Strain" story before.

REHMInteresting. But when an oil well erupts, isn't a certain percentage of it water?

ATLASYeah, once the oil well is spilling into the environment...

REHMRight.

ATLAS...there's water around it…

REHMExactly.

ATLAS...and bacteria are almost immediately colonizing that oil and beginning to grow.

REHMAnd I think that's the basis of Edward's question.

ATLASBut those bacteria tend not to be human pathogens. They tend not to be animal pathogens.

REHMMm hmm.

ATLASThey tend to be the sort of bacteria that we form -- find in natural ecological situations that are not harmful but rather beneficial.

REHMAnd finally, David Guggenheim, which creatures are you most worried about?

GUGGENHEIMYou know, it's really hard to single out any animals because it -- this is an ecosystem issue. This affects everything from algae to dolphins and everything in the food chain. And one of the issues that we haven't even talked about is heavy metals. And while the heavy metal content is pretty low in Louisiana crude, there's the chance -- we know that from mercury that that's something pretty nasty and can concentrate in seafood. And last week at the hearings, we don't even have a clear picture as to the sampling of that. So we're looking at an ecosystem level effect.

REHMAnd finally, what about the Obama administration's decisions on offshore drilling, Juliet?

EILPERINWell, I think that's something that people will be watching in the months to come, that essentially the President had announced less than a month before the blowout in the Gulf, that he was going to expand drilling in certain areas, including potentially the eastern Gulf of Mexico and off the Atlantic Coast, including in this area. And so the administration says now, that got over-interpreted. This just meant we are exploring the possibility. It doesn't mean we're okaying this. They have, in fact, cancelled lease sale of Virginia. But that said, you know, they are going to move forward, and they say they will be looking very carefully at the lessons from the Gulf when they decide where to drill.

REHMJuliet Eilperin of The Washington Post, Ronald Atlas, he's a microbiologist to the University of Louisville, past president at the American Society for Microbiology, and David Guggenheim, president of 1planet1ocean, a project of The Ocean Foundation where is a senior fellow. Thank you all so much.

EILPERINThank you.

GUGGENHEIMThank you.

REHMAnd thanks for listening. I'm Diane Rehm.

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