Dolphin Deaths Continue Along East Coast, May Indicate Poor Ocean Health
As the year draws to a close, the 2013 dolphin die-off has claimed at least 1,000 of the creatures--and the dolphin deaths don't seem to be stopping. The situation has baffled scientists, who have seen eight times the average number of dolphins die along the Eastern Seaboard of the United States. A majority of the dead dolphins have been felled by morbillivirus (marking the worst outbreak since 740 dolphins died 1987-88), but scientists aren't sure why so many dolphins have become susceptible to the virus. Young, old, male, female--morbillivirus has killed all kinds of East Coast dolphins, with no obvious pattern.
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One theory is that virus is simply natural and cyclical, and that 2013 just happens to be one of those years. "The last occurrence of this was about 25 years ago and the animals that survived that would have natural antibodies," said Erin Fougeres, a marine mammal biologist for the National Oceanic and Atmospheric Administration. "But as those animals slowly die out and new animals are not exposed, they may not have that immunity." Fougeres said that another factor in the dolphin deaths could be climate change: "There could be underlying causes that made them more susceptible this year versus other years."
The mysterious 2013 dolphin die-off may also be about more than just dolphins. The morbillivirus deaths, in addition to dolphin deaths from things other than morbillivirus, may indicate an ocean in trouble.
"Marine mammals are very good sentinels for ocean and human health, and they really act like the proverbial canaries in a coal mine," veterinary pathologist Greg Bossart told the New York Times. "They give us an idea of what's occurring in the environment." Bossart said that because coastal-dwelling bottlenose dolphins are top predators with long life spans, "whatever happens coastally impacts them and potentially us."
The dolphin die-off is particularly perplexing and troubling in Florida, where some 80 dolphins have died this year off the east coast of Florida, with an additional 233 dying in the northern Gulf of Mexico. According to the Times, different groups of dolphins seem to be dying for different reasons, among them "disease, a polluted environment, infection and possible residue from the BP Deepwater Horizon oil spill in 2010."
"It is alarming when you see so many different die-offs of marine mammals going on at once," said Fougeres. "We can't say they are linked. But it says there are a lot of challenges that marine mammals are facing."
The NOAA has declared the 2013 dolphin die-off an Unusual Mortality Event.
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