Dolphin die-off tied to Gulf oil spill, other factors
Posted on Aug 09, 2012 in News
ORLANDO, Fla. (MCT) Bottlenose dolphins in the Gulf of Mexico washed up dead along the shores of four states early last year in one of the worst die-offs on record in the region.
Had they been poisoned by the oil that gushed for weeks into the northern Gulf from BP’s stricken deep-sea well less than a year earlier?
Finding evidence of that would be very difficult, if not impossible, said Graham Worthy, a University of Central Florida biology professor who has worked with marine mammals for more than 30 years.
But that doesn’t mean the nation’s biggest offshore spill of crude oil didn’t play a key role in the deaths of the 186 bottlenose dolphins recovered from Gulf waters from January through April last year. Many of the animals were in horrible shape, apparently starving and weakened before death, Worthy said, suggesting that their health and the availability of food — in their case, fish — had been significantly depleted in the months after the BP spill.
“Clearly something was hammering them,” Worthy said of the dead dolphins found on Florida’s Panhandle beaches and along the coasts of Alabama, Mississippi and Louisiana. “It was clear that it wasn’t likely to be a simple cause-and-effect issue but, rather, that there were likely several factors coming together — a perfect storm of impacts — and we felt that we could help try to solve this mystery.”
The examination and assessment of the environmental damage caused by the BP spill — a legal and scientific process that will include the plight of the dolphins and a wide range of other plant and wildlife species — will probably continue for years, said Ben Sherman, a spokesman for the National Oceanic and Atmospheric Administration.
That there is much difficult work ahead was underscored by the recent dolphin study from Worthy and a team of other biologists at Gulf of Mexico research institutions.
Their probe into the 186 dolphin deaths — five to 10 times as many as ordinarily expected in a four-month period — reinforced the thinking of many scientists that most of the environmental harm caused by the 2010 oil spill wasn’t in obvious forms, such as heavily oiled birds, but rather in obscure and probably poorly understood cascades of ecosystem disruptions.
The dolphins, for example, may have been doomed by the confluence of spilled oil, cold waters and poor health.
Worthy and his co-researchers found that nearly half of the dolphins that perished had just been born or were about to be born. They were far too young to have encountered either the BP spill’s floating slicks or its submerged plumes of crude oil, though they might have been conceived during the spill, which began April 20, 2010, and continued for more than 85 days.