AUDIE CORNISH, HOST:
To understand what the environmental impact of the BP oil spill has been over the last two years, we turn now to Dr. Jim Cowan. He is a professor of oceanography and coastal science at Louisiana State University. Dr. Cowan, welcome to the program.
DR. JIM COWAN: Happy to be here.
CORNISH: So you've been out on the water examining the impacts of the spill since the early days. What were the sort of concerns at first and how has that changed over time?
COWAN: Well, we've been studying the fish communities in the Gulf for several years. And so we were fortunate enough to be in a position to have pre- and post-spill information. So we had a good baseline data set from which to compare the work that we're doing now. And I'm certain that the acute impacts of the spill are behind us, but I'm much less certain that we have avoided chronic impacts that may be a problem for quite a while to come.
CORNISH: And by chronic impacts, you mean what?
COWAN: Well, I mean, chronic exposure to toxic materials cause all sorts of problems with immune deficiencies and in some cases even deformities, which we've seen in crabs and shrimp. And we're seeing a fair number of fish that have sores on their sides, and we don't know what the actual fate of those is, but I can tell you the abundance of some of those fish have declined over time.
CORNISH: Can you talk about what the concerns are for humans? I mean, has any of this entered our food chain? Should we be concerned?
COWAN: Well, fortunately, what we're talking about are fish, but none of these animals are making it to the market. Any that have any kind of symptoms like we're describing, the fisherman are very acutely aware of that. And so there is - this is really a biological health issue or an ecosystems health issue and not a seafood health issue. The industry is screening seafood, and they're very aware of the issues, but they're also not letting any of this stuff enter the market.
CORNISH: There's been a lot of discussion about the impact of the oil but also the potential impact of the dispersants which were used to break up the oil. What do we know right now? What does the research say about the impact of either one of these?
COWAN: Well, what the research says from the eco-toxicology community suggests that the oil-Corexit mixture is more toxic than either of the two elements on their own or the two substances on their own.
CORNISH: And Corexit is the name of the oil dispersant that was used to help the cleanup.
COWAN: Yes, it is. Yes. And the problem with oil on the seafloor is that it's technically impossible to clean up because the oil-Corexit mixture is settled in deep waters that are very cold and the process of biological degradation is much, much slower.
CORNISH: What are some of the unanswered questions that researchers are looking at now? What are the concerns?
COWAN: Well, first of all, how much oil is still on the seafloor and how will it be remobilized, or whether it'll be remobilized before it weathers away. We know from experience with Hurricane Isaac that we were quite surprised that after the storm had passed, we found seabirds that were oiled, and it was traced to the Macondo well. And so if there's oil still out there in the sediments that is capable of oiling birds, it's not weathering very quickly. And that's our - our concern is how much of it's out there and how long will it last because as long as it's out there and has the ability to affect wildlife and fisheries, it's going to be a problem.
CORNISH: Dr. Jim Cowan, thank you so much for speaking with us.
COWAN: Happy to speak with you, Audie.
CORNISH: That's Jim Cowan, professor of oceanography and coastal science at Louisiana State University. And we should note BP is expected to face further civil charges for environmental damage. Transcript provided by NPR, Copyright National Public Radio.