By Rachel Kaufman
What we know about what’s happening in the Gulf of Mexico is that the oil spill is very, very bad for wildlife, humans, and the environment.
What we don’t know, many experts are saying, is exactly what that means.
Susan Shaw is a marine toxicologist and the director of the Marine Environmental Research Institute. She’s been studying how chemicals affect marine animals for two decades, and is now working on the effects of spilled oil and chemical dispersants on dolphins, coral, shrimp, and other Gulf species.
The problem, Shaw told Nat Geo News Watch, is that there’s so much uncertainty: nobody knows exactly what’s in Corexit, the chemical dispersant BP’s been using to clean up the oil, and there’s no one body studying the food web as a whole. “The [government] agencies are overwhelmed,” Shaw said. “There are certain species being monitored, but it’s all separate. No-one’s putting the whole picture together.”
Even if the entire food chain–from the tiniest plankton to the biggest predator–was being studied, the effects of the spill will likely be more complicated than anyone could predict, she said. She pointed to the effects of the Exxon Valdez spill in 1989. Researchers had assumed they knew what would be affected by the tens of millions of gallons that covered 1,300 miles of coastline, based on a food chain that looked like this:
Turns out, the food chain in Prince William Sound was much more complex than anyone had realized, and thanks to the oil spill knocking a few species out entirely, researchers learned that the ecosystem looked a lot more like this:
The sea ducks, dependent on a certain species of barnacle for food, were wiped out in huge numbers when the Exxon Valdez oil destroyed the barnacles. Nobody had predicted this, Shaw said. “We thought you started with kelp and went up the food chain, but in fact what happened was much more complex and specific.”
Now, she said, we think we know the food webs and relationships in the Gulf, and we think we know what will be affected by the oil and Corexit, but “it’s going to be much more complicated” than anyone could guess.