After Hurricane Katrina struck the Gulf Coast in 2005, scientists noticed bottlenose dolphins had developed ulcers and lesions all over their bodies after being caught in a brackish lake. Since Hurricane Katrina, reports of these gruesome sores on dolphins have increased in the United States, Australia and South America—and puzzled scientists have been working to identify the disease, Elle Hunt reports for the Guardian.
Fifteen years later, they finally have an answer. In a study published in Scientific Reports in December, the team of scientists named climate change as the root cause of this painful skin condition, reports the Miami Herald's Katie Camero.
Reports of the disease have increased in tandem with more frequent extreme weather events, like hurricanes and cyclones, study co-author Nahiid Stephens, a veterinary pathologist at Murdoch University in Perth, Australia, tells the Guardian. In extreme weather, storms dump freshwater into the ocean, decreasing the salinity and changing its chemistry. Dolphins can tolerate freshwater for short periods of time, but they developed painful lesions after the storms as a result of prolonged exposure to freshwater, which can last for months on end, reports the Miami Herald. In some cases, the team found that the lesions covered more than 70 percent of a dolphin's skin.
With open wounds, ions and proteins can ooze out of their skin as freshwater rushes in. Ultimately, the lesions cause electrolyte disruptions in the blood stream, leading to organ failure, Stephens tells Peter Dockrill for Science Alert. Plus, the open lesions provide an entryway for fungus, bacteria and algae to cause a further infection. The lesions are so devastating that they're on par with third-degree burns on humans, reports the Guardian.
"Their skin is just as sensitive as ours, and possibly even more so—it would be incredibly painful," Stephens tells the Guardian. "We couldn’t believe that such a severe, rapidly developing disease could be anything other than infectious … but ultimately, it is an environmentally caused disease."
Each region the scientists studied has experienced dips in ocean salinity as a result of more frequent and powerful storms. And as climate change continues to fuel more intense storms, the scientists expect prevalence of the disease to boom, too, reports the Miami Herald.
"We can only say there’s a pattern, a trend—but it’s gathering strength," Stephens tells the Guardian.
"This year was a record hurricane season, and who knows about next year," Pádraig Duignan, the chief pathologist at the Marine Mammal Center in California, tells Tiffany Duong for EcoWatch. "More Katrinas and more Harveys might be on their way, and each time, this will be happening to the dolphins. I think it will get worse."
Despite the grim news, the scientists are "pleased to finally define the problem," Pádraig says in a press release. The team can't cure climate change, but the findings will allow scientists and veterinarians to diagnose and treat the lesions now that they know what it is and how it's caused.