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Scientists working to find what's killing dolphins

5:13 PM, Aug 25, 2013   |    comments
Winter the Dolphin
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ASBURY PARK, N.J. -- On a Pennsylvania farm 70 miles from the ocean, inside a sprawling laboratory built to treat horses and other four-legged animals, scientists are trying to solve this summer's greatest sea mystery:

What is killing the dolphins?

Many of the dead dolphins that have washed onto the Jersey Shore since July 9 have ended up on metal tables and under the knife in the pathology lab at the New Bolton Center, a large-animal facility in Kennett Square, Pa. The facility is part of the University of Pennsylvania's School of Veterinary Medicine, in the southeastern part of that state near the Delaware line.

A team of board-certified veterinary pathologists cut into each dolphin to perform a necropsy that involves at least an hour of removing major organs and identifying potential abnormalities.

That is just the start of the search for the elusive killer. Many more hours are spent on the hunt. Organ tissues are examined under microscopes. Tests with antibodies, a sign of what is affecting the mammals' immune system, could turn up clues, perhaps providing enough data to help scientists see the big picture.

"One of the saddest things to see on these creatures is some have horrible pneumonias and ulcers so you know that they are suffering. And the shark bites are kind of sobering to look at," said Dr. Perry Habecker, chief of large-animal pathology at the New Bolton Center.

The center's expertise is in working with horse cadavers, then some bovine, and then a mixture of farm and zoo animals, he said.

But a two-decade-old relationship with the Marine Mammal Stranding Center in Brigantine, N.J., has brought very different animals to the lab. The pathologists are attempting to uncover the truth behind the death of more than 200 bottlenose dolphins that have washed along the beaches of the mid-Atlantic coast since July 9.

Morbillivirus, known for its role in a massive die-off of 742 bottlenose dolphins on the East Coast in 1987, has been found in some of this summer's dead dolphins. But scientists and experts aren't ready to label the virus as the killer yet.

The dolphins are being carefully studied for signs of that virus as well as toxins, biotoxins, bacteria, pollutants and any other potential culprit, said Maggie Mooney-Seus, the National Oceanic and Atmospheric Administration's Northeast Fisheries Science Center's communications specialist.

"We haven't ruled anything out yet because we have had animals from a pretty wide area and we have to look at everything that could be behind this," she said.

One thing Robert Schoelkopf, director of Brigantine's stranding center, can rule out is superstorm Sandy.

"Somebody tried to suggest that the oil spill in the Gulf of Mexico a couple years ago was to blame. There's no way," he said. "Sandy was a natural occurring hurricane. You have it all over the world and you don't see this happening after a hurricane every time. There's no tie at all with that."

Schoelkopf, whose center staff picks up the carcasses and drives any that aren't badly decomposed to the New Bolton Center, spotted trouble almost immediately when dead, marked up dolphins started washing ashore in early July.

"As soon as I saw the first animal that came in with the lesions on it and the lung infection, my mind shot right back to 25 years ago when I did the same thing," Schoelkopf said.

In 1987, when morbillivirus took its toll on hundreds of bottlenose dolphins, Schoelkopf witnessed the death of 93 animals in New Jersey alone.

In early August, NOAA Fisheries felt the sheer number of deaths compared with prior records justified declaring them as an Unusual Mortality Event. The classification is used for unexpected, significant die-offs of any marine mammal population and allows researchers more funding and other resources to find the cause.

There have been 60 recognized Unusual Mortality Events since 1991 and just 29 were resolved with a cause.

But because of NOAA's declaration, Habecker's team are pulling tissue samples - specifically from the lungs, anus and blowhole, which lend themselves to virus culture - to be sent to labs in Florida and California. Those labs are among few in the nation with the expertise and facilities to look for what kind of viruses might be at play here, Habecker said.

In his own lab, in addition to the gross autopsy, Habecker will examine sub-sectioned tissues on slides under a microscope. Then his team subjects those slides to an antibody, which will show a reaction if morbillivirus is present.

"We know it's out there. It's always been out there, but we don't know why we're seeing some more of it," Habecker said of the virus.

Knowing the cause of the dolphin's illnesses and eventual deaths should give the experts and scientists involved an idea of whether this is a natural occurring illness that happens in a cycle or if it started by something humans are doing, such as pollution, Mooney-Seus said.

"You have to look at everything so you can look for opportunities at remedying it if we can," she said. "It shows something is definitely going on in the ecosystem and that's why we have to look at all those environmental factors as well."

Habecker said historically, pneumonia is the most common cause of death, and there is also a parasitic worm that impacts the brain and can kill dolphins. He said he has seen a variety of things and, like other experts involved, is looking for patterns.

His experience in veterinary pathology tells him that some viruses drive down the immune system so severely that an animal can become susceptible to other problems. So the dolphins may contract morbillivirus, become weakened by it, but ultimately die from something else such as pneumonia. It can have a similar impact as measles in humans, he said.

Larry Hajna, spokesman with the New Jersey Department of Environmental Protection, said at least four dolphins have showed signs of the morbillivirus and each of those four died from pneumonia.

Because only dolphins have washed ashore, instead of a variety of sea animals, indicates these deaths are related to a disease cycle, Hajna said.

"It's naturally occurring and it's something that's going to happen again down the road, maybe in another 25 years," Schoelkopf said. "That's the idea of doing the extensive tests like this, that they can possibly find somewhere or some way around the problem."

Considering 1987, Schoelkopf said the deaths seen in New Jersey will probably taper off near the end of September.

Because of all the necessary testing, what was initially a 48-hour process from the time a dolphin is picked up on the beach to the end of the testing, is now taking at least three weeks, Schoelkopf said.

Since the Unusual Mortality Event was declared, the New Bolton Center has taken in 33 dolphins, but Habecker said they had received some before that point, too.

When there are fewer dolphin carcasses along the Jersey Shore, that won't mean the problem was resolved, Schoelkopf said. The dolphins' annual migration south could mean more deaths are reported in southern states, he said.

Mooney-Seus noted that already more dead dolphins are cropping up in North Carolina. July and August saw the majority hit no farther south than Virginia, which has seen the highest body count in July and August with 141, including 25 from last weekend alone, said Joan Barns, spokeswoman for the Virginia Aquarium & Marine Science Center.

Schoelkopf continues to urge anyone who sees a dolphin, whether it's in the water or on shore, to keep away from it. Sharks have been know to attack the dolphins, most of which die before they come on land, and pose a danger, he said.

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