If you think proving a negative is difficult, try showing how many critters were killed by BP’s oil spill – without any bodies for evidence.
That’s just one of the challenges causing migraine-level headaches for biologists charged with measuring the impact of BP’s gusher on waterfowl for the official Natural Resources Damage Assessment (NRDA). Unlike dolphins, pelicans or sea turtles, ducks don’t wash up on shorelines or float in the currents when they get sick and die. They head for cover inside the marsh, where they quickly become food for a long list of predators.
And that presents a big, big problem. The NRDA process eventually leads to a bill the responsible parties for a spill must pay. It’s a legal process, a court fight in which heresy typically doesn’t count for much.
“We’ve been asked to come up with evidence of how many waterfowl have been killed and harmed,” said Larry Reynolds, waterfowl study leader at the Louisiana Department of Wildlife and Fisheries. “Well, there are all kinds of models for assessing impacts on wildlife in habitat with rocky shorelines or long sand beaches. But, except for some barrier islands, we don’t have any of that in Louisiana.
“And, worse, ducks aren’t like colonial nesting birds (pelicans) or those other animals that float on the surface of open water when they die and are easy to collect and count. No, when a duck gets sick or is wounded, they crawl into the thickest cover they can find, and you never see them again.
“So, none of those models work here. And that’s been part of our problem.”
Another part of the problem is the timing of the spill – both past and future.
The heaviest inflow of fresh oil occurred during the summer, when migratory waterfowl were still far to the north. But spill experts have said residual oil – oil that is sitting under sediments along the coast or on the bottom of the Gulf of Mexico – will continue to resurface for months if not years, especially during those hard southwest blows that precede winter’s cold fronts.
Pass-a-Loutre Wildlife Refuge at the mouth of the Mississippi River is of particular concern. It hosts one of the largest wintering populations of migratory waterfowl in the Gulf South, and unfortunately, it was one of the hardest hit areas by BP.
“Clean-up crews have been working there since the beginning,” Reynolds said, “but there’s still so much oil in the substrate in some places, that if you run a motor over shallow water, you not only turn up globules of oil, you leave a long sheen in your wake.
“Well, birds are already starting to arrive. Will they get hit by this, and how will we be able to tell?”
Then there’s the threat that most scares biologists: Long-term degradation of the habitat base that could take a toll on ducks and geese – not to mention hundreds of millions of other migrants – for years to come.
Some toxic components of the oil known as polycyclic aromatic hydrocarbons (PAHs) have a shelf life of up to 50 years. They could take a toll on food sources, reducing the habitat as a fuel source for birds resulting in a lower survival rate on the return migration. Or they could contaminate food sources and pose a threat to wintering birds.
How do you assess that threat? How do you know the worst is happening, if you don’t find any bodies?
Reynolds says the LDWF is drawing up proposals to meet those challenges.
“We’re looking at habitat alternations and (bird) tissue assessments from areas hit by the spill, and compare those to samples from areas that were not touched by it,” he said.
For example, biologists will take samples of plants and tiny critters waterfowl feed on in the coastal wetlands.
“We have anecdotal evidence that the physid snails which waterfowl feed on especially during molting are practically gone from the areas that were hit by oil,” Reynolds said. If that turns out to be oil related, a case can be made for the impact on ducks.
“We’ll be taking tissue samples from birds that winter in the areas that were hit by the oil on our coast, in areas of our coast that we think were not hit and from birds that stop in states north of us before they ever get here,” he said. “We’ll be able to compare the analysis to see if they are accumulating these harmful chemicals, such as the PAHs.”
Those are the right moves because as scientists have said since the beginning of BP’s deadly mistake, we won’t know the long-term impacts of the greatest act of pollution in American history until we get there. University of Miami researcher Jerald Alt has the right analogy: “We’ve been put in a movie, and we don’t know the ending.”
The bodies needed for the NRDA court fight may be falling in the marsh for years to come – or not.
It’s a headache the LDWF needs to solve before BP gets to walk.