Posted: 09/18/2013 at 5:59pm | IP Logged

Huge Dolphin Die-Off Puzzling Marine Biologists

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CBN News

VIRGINIA BEACH, Va. -- Dolphins are dying at an alarming rate along the East Coast. Hundreds have washed ashore, and marine biologists are scrambling to examine the animals.

It's an ominous site. A large male bottlenose dolphin lies dead on the Virginia coast, while other dolphins swim by -- potential victims of what's been declared by scientists as an "unusual mortality event" in the Mid-Atlantic region.

Since early July, strandings of bottlenose dolphins have jumped from New York to North Carolina. In fact, for the months of July and August, these strandings were more than nine times the historical average, reaching a total of 430 through Sept. 2.

In Virginia, the Virginia Aquarium Stranding Response Team has been recovering the dolphins and transporting them to the Marine Animal Care Center in Virginia Beach, Va. There, marine biologists have been performing what's called a "necropsy" on each dolphin to determine the cause of death.

Magnitude of the Crisis

For a better idea of the magnitude of the crisis, on average in July each year, the Stranding Team recovers around six to seven dolphins. In July this year alone, however, they recovered just shy of 50.

"We examine the entire animal, outside and inside," Sarah Rose, assistant stranding technician, told CBN News. "So we do an external exam to look for any signs of human interaction. We also look inside to see if there are any unusual pathologies."

"One thing we've been seeing are oral lesions on the animals, so lesions around the mouth, and internally, the lungs seem to be an affected organ -- lots of lesions in the lungs, although there's been some variability with what we see," she explained.

"We're taking a ton of samples," Susan Barco, research coordinator for the Virginia Aquarium & Marine Science Center, told CBN News.

Those samples are shipped all over the country to different labs for analysis.

Migratory patterns cause a great number of bottlenose dolphins to make their way into the waters off the Virginia coast.

"We have a lot of dolphins here, and we think that that's the reason why we've had so many strandings," Barco said. "If this disease is affecting a certain percentage of the population, if you have more dolphins, then you would expect to see more strandings."

Humans Beware?

But what's killing them? Barco said research shows it's the naturally occurring morbillivirus, which is related to the virus that causes the measles in humans.

"Once the morbillivirus gets into the coastal population, the animals are very social, and it's relatively easy for transmission to occur," Barco explained. "Just when animals are near each other, one breathes out, another breathes in when they have contact with each other."

And if humans come into contact with the dolphins? Barco told CBN News the morbillivirus itself is not a "zoonotic disease," which means that it cannot be transferred between animals and humans.

But people are not totally in the clear.

She explained that not all the dolphins are dying strictly from the morbillivirus; it weakens their immune system, and they get other infections such as fungal and bacterial, which can affect humans.

"So we do want to be very careful around these animals," Barco said. "What they're dying from or what they're catching is in the water, and so anybody that has a compromised immune system, or an open wound, should be careful when they're swimming in the ocean anyway and certainly shouldn't be near these animals."

Caring for Our Mammals

Right now there is no way to prevent the spread of the virus among dolphins and no vaccines or anti-viral medications.

The last major die-off of this kind happened in the late 1980s. In 1987 and 1988, a similar event depleted the coastal migratory bottlenose dolphin sub-populations by half.

That makes scientists very concerned about this year.

"We've already in Virginia surpassed the number of animals that were estimated to have died in the 1987-88 die-off, and we still have several months of time to go that dolphins are in this area," Barco said. "So understanding how these animals are affected by this mass die-off is really important."

"These are everyone's animals. Marine mammals are protected by the Marine Mammal Protection Act, but they're protected because they're everyone's animals," Rose said.

"And they're a higher species in the food chain in the ocean, so when there's something wrong with them, it's usually an indication that we should look at our ocean as a whole to see if there is anything wrong," she said.

The 1987-88 die-off lasted 18 months. Scientists fear this event could last that long as well.

Source: CBN News