The Miami Herald

Oil slick expected to take its toll on dolphins in Gulf

For now, desperate oily pelicans are the gut-wrenching image of the Deepwater Horizon oil spill.

But before long there will be others, including the most beloved sea creature of all, the dolphin.

"We're going to lose a lot of them," said Dr. Denise Herzing, research director for the Wild Dolphin Research Project in Jupiter. "It is unconscionable and it is criminal. It is akin to a nuclear power plant explosion underwater."

As of Wednesday, there were 51 confirmed reports of marine mammal strandings involving oil: one sperm whale, 3 spinner and 47 bottlenose dolphins collected in the Gulf — dead or alive — since the Deepwater Horizon spill on April 20. Four of those dolphins were found along Florida's Gulf coast:

A visibly oiled bottlenose dolphin also was found trapped in a boom in Perdido on Florida's western border, but when the boom was moved, the dolphin swam away.

Three dead spinner dolphins were also found, one on Mexico Beach, south of Panama City, with no signs of oil, another with serious injuries from a shark attack that was euthanized on a Panama City beach and one as far east as Venice, just south of Sarasota, also with no signs of oil.

It is not known if oil from the Deepwater Horizon spill killed the dolphins. Necropsy results are pending. Dolphin strandings are not uncommon. Last year — one of the better years — only 128 dolphins were discovered stranded on Florida's shores. About 40 percent of those were in the 22 counties along the Gulf of Mexico.

Although oil and tar will not stick to a dolphin like it does to fur and feathers, dolphin — unlike fish — breathe air. Every time they surface, they will swim through the toxic slick and breathe fumes at the surface.

While dolphins are among the smartest animals on the planet, researchers do not know if their intelligence will protect them from the oil.

"I think they are smart enough to realize they are in bad water and they need to get out," said Beth Smart, founder of the Dolphin and Marine Medical Research Foundation in West Palm Beach. "However, they also travel in pods and stick together."

Dolphins have long lives, and several generations of one family may live together in a pod. That loyalty to each other can be fatal, Herzing said.

"There have been some reports of dolphins stranding together because they are families," Herzing said. "If one gets sick they hold him at the surface to breathe."

The biggest threat probably will come from eating fish contaminated with oil. Eating toxic fish could suppress the dolphins' immune system, making them vulnerable to pneumonia and other illnesses, Herzing said. Another marine mammal facing death by food poisoned with oil are baleen whales, which often feed on plankton at the surface.

Dolphins, though, are unique among the animals likely to be affected by the oil not only because of their nature but because of ours. Modern humans appear to feel a connection with dolphins that they don't even with other marine mammals, perhaps in part because of marine theme parks that have provided people an opportunity to interact with dolphins, even to the extent of swimming with them in some places.

The Dolphin and Marine Medical Research Foundation has a dog trained to alert on dead and distressed marine mammals, Smart said. Cloud, a 4-year-old female black Labrador retriever, is the only dog the foundation is aware of that is able to pick up scents and sounds from the bow of a boat and lead rescuers to the animal.

For now, Cloud has not been able to work in areas hardest hit by oil — where the fumes are still strong and toxic. Even though she has a vest and boots, "if there is any chance she is going to be in contact with the oil, we're not going to endanger Cloud," Smart said.

While dolphins in the Gulf have been widely studied, there are few data on dolphins off Florida's Atlantic coast. What impact the oil will have on them if the loop current pulls the weathered oil to the east coast is not known.

"We are going to see a change but we don't know what it is," Smart said. "We're kind of waiting for mother nature to give us a clue."

For now, desperate oily pelicans are the gut-wrenching image of the Deepwater Horizon oil spill.

But before long there will be others, including the most beloved sea creature of all, the dolphin.




© 2010 Miami Herald Media Company. All Rights Reserved.
http://www.miamiherald.com