A deadly virus that killed tens of thousands of harbor seals in the North Atlantic in 2002 suddenly spread to sea lions, seals and otters in the North Pacific two years later, confusing scientists, as NBC News reported.
How can the pathogen that causes a measles-like disease in marine mammals found only on the Atlantic coasts suddenly spread to the Pacific?
"We didn't understand how a virus from the Atlantic ended up in these oceans. It's not a species that extends much," said Tracey Goldstein, a University of California Davis researcher who investigates how pathogens move through marine ecosystems, which National Geographic reported.
Goldstein and her colleagues looked at 1
"The loss of sea ice leads the ocean's wildlife to seek and forage in new habitats and remove the physical barrier, allowing new paths for them to move," Goldstein said in a press release. "When animals move and come into contact with other species, they have the opportunity to introduce and transmit new infectious disease, with potentially devastating effects."
The rapid loss of sea ice creates a fertile breeding ground for viruses when animals travel to areas they have never been before. The phenomenon was first observed 17 years ago.
"It was a perfect storm in 2002," said Goldstein, as NBC News reported. "It was the lowest ice year on the record then, and at the same time, in August and September, there was a really big outbreak."
To study the outbreak, researchers took blood and mucus samples from seals, sea lions and otters from arctic and subarctic areas, from southeastern Alaska to Russia. The fungal samples allowed researchers to determine which populations had been infected with the Phocine distemper virus, or PDV, and which specific strain they had been exposed to, as NBC News reported.
PDV is a common canine virus that veterinarians vaccinate for. It spreads easily when an animal comes into direct contact with an infected animal. The virus is manifested in seals, just as the dog version does in dogs – goop released from the eyes and nose and fever. With marine mammals, it also leads to independent swimming, according to National Geographic.
"The virus has been found to spread quite easily among marine mammals," Shawn Johnson, vice president of veterinary medicine at The Marine Mammal Center in Sausalito, California, told National Geographic. Because so many marine mammals migrate north, "the Arctic can be a perfect melting pot for transmitting the disease," Johnson said.
Not only is the changing landscape of the Arctic allowing animals to travel longer, animals that need to travel longer for food will experience extra stress and fatigue, weakening their immune systems and leaving them susceptible to disease, Goldstein told National Geographic.
The study contributes to a growing body of research signaling problems for marine mammals, including an increase in marine heat waves that lose their food supply and an increase in toxic algal blooms that can infect fish with a toxin causing brain damage in marine mammals, such as NBC News reported.
"When we see these changes happening in animals, we cannot ignore them because the effects on humans and the planet are not far behind," said Elizabeth VanWormer, the study's lead author, as NBC News reported. "This shows how these things are interconnected – the health of humans, animals and the planet."
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