A Sea in Flames - Carl Safina [122]
One way of seeing if invisible oil-eating microbe populations are active and growing is to measure oxygen, since microbes use up oxygen. So one research team notes that oxygen levels haven’t declined much, implying that the oil down deep is degrading slowly (it’s cold down there—40° Fahrenheit). Until more puzzle pieces start coming in, it’s a bit puzzling.
Everyone agrees that oil is toxic, but the plain truth is, no one can say how toxic it is out in the Gulf. That’s because the concentrations vary from place to place and continually change. Laboratory tests are usually done by putting organisms such as shrimp or fish larvae in a mixture of water and the chemical they’re testing, and seeing what concentration kills half the organisms in forty-eight hours. Researchers want results, so the concentrations are fairly high. But they want acute results—death. Doing experiments on the effects of very low concentrations means needing more samples and much more time, which translates into money. Too expensive, so seldom done.
And real ecosystems are so much more complicated that a laboratory experiment doesn’t help us understand the fate of chemicals in the Gulf’s living communities. If a research team finds oil and dispersant chemicals in the Gulf at concentrations a hundred times lower than the concentrations that killed half the larvae during two days in the laboratory, does that mean half the shrimp and fish larvae will die in two hundred days instead of two? No, it doesn’t. But that also doesn’t tell you whether the lower chemical concentrations will hamper the organisms’ ability to continue finding food, grow normally, avoid predators, migrate, fight off infections, and so on. So when a scientist says, “We don’t know how toxic it is,” that’s the truth.
But let’s ask it another way. Let’s look at trends. Is stuff dying? What isn’t dying? What about recovery—are any components of the Gulf or its coastal marshes showing signs of bouncing back? Or not?
Now, here’s the thing: though there’s still a lot of disagreement, suggestions that the oil is rapidly disappearing are beginning to come from various independent sources. Even before July rolls over to August, the floating oil mats that covered thousands of square miles of the Gulf are largely gone. Remaining oil patches are quickly breaking down in the warm surface waters.
“Less oil on the surface does not mean that there isn’t oil beneath the surface, or that our beaches and marshes are not still at risk,” says NOAA chief Dr. Jane Lubchenco. “The sheer volume of oil that’s out there has to mean there will be some very significant impacts. Dilute does not mean benign.”
That’s true. But it might also be fair to bear in mind that dilution is what pollution passes on the way to benign. In other words, the trend seems good.
My friend the tugboat captain is heading back to shore from another trip into the Gulf. This time he’s off Florida, approaching Pensacola. And this time he’s got good news: he’s seeing numerous schools of the tuna cousins called little tunny. Because he’s driving a boat in open water, he’s got plenty of time to talk.
What are his impressions?
Despite the fish, “a lot of the water just looks off,” he says. “What it usually looks like and what it looks like now are two different things. I know that’s very subjective. I haven’t seen any obvious slicks recently; it just looks off. It’s like an old piece of Plexiglas; it just doesn’t have that clarity like when it was new. Ever so slightly opaque.
“And I’ve pulled up a bucket of water that seemed perfectly clean, but it feels slimy. Like I say, the closer to the well, the worse that was. I’m accustomed to seeing large areas of sargassum. I’ve seen none of that. What you see is little bits, like it was run through a food processor, nowhere near the amount I would normally see, and no big patches. And I’m looking