Nancy Rabalais on long-term impact on wildlife of Gulf oil spill

Scientists say it might be 10 years before we know the impact on wildlife of the Deepwater Horizon oil spill in the Gulf of Mexico. Sensitive coastal marshes are a special area of concern.

Scientists say it might be 10 years before we know the impact of the Deepwater Horizon oil spill in the Gulf of Mexico on wildlife.

Nancy Rabalais: It seems that a 10-year period might be realistic for no longer needing to track the environmental impacts. Although I think in 10 years you can still probably dig trenches through beaches and still find evidence of oil.

Nancy Rabalais is an oceanographer at the Louisiana Universities Marine Consortium. EarthSky asked her which Gulf species were of greatest concern for scientists.

Nancy Rabalais: Some of the oyster beds in shallower waters that received oiling, if there is still oil in those sediments. That’s a big concern for the oyster fisheries. A lot of the birds are of great concern. How the area will repopulate from loss of birds, or if birds were cleaned, they were usually moved to an area where there was not oil, and then released into a clean environment. Whether those organisms will repopulate this area, or if the area will just repopulate itself.

Rabalais said that because chemical dispersants were used to break up oil slicks, the oil itself is hard to track, making the Deepwater Horizon spill more difficult to study than previous oil spills.

Nancy Rabalais: Where is the oil? Where do we see signs of oil? What’s its toxicity? What’s its chemical composition? How is it affecting the environment, the habitat, the shrimp, the fish?

She said the future of the plants and animals that live in the Gulf is still uncertain.

Nancy Rabalais: It’s a bit early to come up at least ecosystem level, or habitat level, with estimates of what the effect is at this point.

Dr. Rabalais said that scientists are learning what has happened to the oil since it leaked from the well.

Nancy Rabalais: We do know a whole lot more about where some of the oil went and how much has gotten into subsurface plumes, although we don’t know the distribution and eventual fate of those subsurface plumes. We continue to have maps of where oil is in the marshes. There’s still some oil offshore on the surface waters, because it’s still being reported. We just saw it about a week ago on one of our cruises.

Back in April, Rabalais told EarthSky that she was concerned about oil reaching sensitive marshes, which serve as nurseries for species like fish, shrimp, and crabs. She said the oil could be a setback for long-term population growth, and that is now a target for study.

Nancy Rabalais: We do know that there are marsh areas that are oiled, some more heavily than others. We know that some of the marshes have died back, but we know that some of the oiled marsh has new green shoots coming up through the sediment. We know that where oil has been seen before and not now, if you disturb the sediments the oil will come up. There’s still so much not known about where the oil is, it’s hard to come up with ecosystem level or population estimates of what the effects are.

Lindsay Patterson