J. D. Heyes
August 9, 2013
Environmental damage and an increase in toxins caused by human activity are believed to be responsible for a dramatic uptick in dolphin deaths along the East Coast this year, experts say.
In Maryland, seven bottlenose dolphins have recently washed ashore, “part of a larger mystery along the Mid-Atlantic coast, where alarmed scientists are working to find the cause of more than 120 dolphin deaths since June,” the Baltimore Sun reports.
All seven dolphins were discovered in the Chesapeake Bay and on beaches along Maryland’s Atlantic cost during the month of July, the paper said.
Normally, say marine biologists, only a single dolphin might be found dead and washed up on shore during July.
Increase in dolphin deaths up and down East Coast
Cindy Driscoll, veterinarian and fish and wildlife health program director for the state Department of Natural Resources, said several of the carcasses that have washed ashore were “very decomposed” when they were found, which made it difficult to figure out why they died. State officials, however, have sent several tissue samples to labs in a bid to gather more information.
Thus far, scientists believe large toxic algae blooms or some sort of virus might be responsible. Per the Sun:
Dolphin deaths have been reported this summer from New Jersey to Virginia, with the greatest numbers in those two states. The total count troubles scientists, who are waiting on lab results to determine whether it is, indeed, a crisis.
“It is alarming since it’s much higher than normal and in such a short amount of time,” Jennifer Dittmar, the stranding coordinator for the National Aquarium in Baltimore, told the Sun. “As far as an overall effect it’s having on the population, it’s hard to tell right now.”
Driscoll said that in Maryland, 15 dead dolphins have been discovered ashore since January. Normally, in a year, only about 10 or so wash up.
Down the coast in Virginia, the numbers of dolphins washing ashore is also much higher. So far, 87 of the mammals have been found since June; in a normal year, some 50 dolphins wash ashore, most of them grouped around Virginia’s portion of the Chesapeake.
Further north, in New Jersey, 21 dolphins have washed ashore, up from about a dozen or so in a regular year.
“Bottlenose dolphins live in pods and can be found along the East Coast from New Jersey to Florida. The mammals spend the winter in the temperate waters off the Southern states, then come north to the bays, sounds and open waters off the Mid-Atlantic coast from May to October,” the Sun reported.
Dittmer said that, in Maryland, pods of as many as 30 dolphins follow schools of fish far up the Chesapeake. She also said her job is to rescue stranded dolphins, but so far this year, none that have washed ashore have been found alive.
A virus linked to biotoxins?
What’s more, it could be months before scientists and marine biologists have any answers. Necropsies – the veterinary equivalent of autopsies – are currently underway on mammals that have been found. But finding a cause of death takes a great deal of time. And it could be even longer to find out if there is a link between them.
Susan Barco, the research coordinator for the Virginia Aquarium and Marine Science Center Foundation, told the paper that early findings indicate some sort of sickness. If that turns out to be the cause of death, she says it would be significant.
“This is really frightening because these animals are sentinels of ocean health,” she said. “Strandings have been much more common in the past few decades, and we think it’s an indication of the health of our ecosystem.”
It’s also likely that environmental factors are in play, scientists say. Specifically, the accumulation of heavy metals or exposure to biotoxins through the food dolphins consume could be causing widespread mortality.
This article was posted: Friday, August 9, 2013 at 5:25 am