I know most of the SEANET blog’s readership is not naive enough to think that the BP spill’s impacts were limited to the Gulf, but a study underway in Minnesota is now confirming its wide ranging effects, at least in pelicans. The massive American White Pelican winters in the Gulf but heads north to the upper midwest and prairie provinces of Canada to breed. Minnesota Department of Natural Resources biologists have begun sampling eggs in the state and testing them both for traces of petroleum and for the chemical dispersant Corexit used to break up the oil after the BP Deepwater Horizon spill. Over 90% of the eggs tested positive for petroleum and 80% for Corexit. The researchers point out that without a baseline prior to the spill, it’s impossible to attribute these levels directly to the BP disaster. Oil, in particular, is constantly entering the marine environment via spills large and small, many never officially reported. The birds could pick up oil through contaminated prey or directly from the environment. The situation with Corexit is a bit more intriguing; if the test for the compound is indeed highly specific, it would be interesting to know where else all these pelicans could have been exposed to it. I have no information on how wide ranging use of this dispersant is, and I look forward to the publication of the Minnesota results to see what they have to say on the subject.
Regardless of the source, the high prevalence of these contaminants in pelican eggs is troubling. Many petroleum based products act as carcinogens or as endocrine disruptors and need only be present in trace amounts to have profound effects. Just as pregnant women are urged to be vigilant about chemical exposure during the sensitive period of embryonic development, so too are these embryonic birds vulnerable to these foreign chemicals. The science of endocrine disrupting chemicals is still in its infancy, and it’s uncertain what long-term effects these contaminants may have on the populations of exposed seabirds. As usual, we humans are running a real-time, inadvertent experiment in the uncontrolled laboratory of the marine ecosystem. We’ll see what the Minnesota folks turn up from their piece of it when their study is complete.