Mysterious and deadly dolphin disease has been linked to climate change

Scientists have discovered that a deadly skin disease affecting dolphins is linked to climate change, according to a new study from The Marine Mammal Center. This is the first time since the mysterious dolphin disease first appeared in 2005 that the cause of the condition has been identified.

The researchers have determined that the disease, which has affected dolphins worldwide, is caused by decreased water salinity associated with climate change. The infected dolphins develop patchy and raised skin lesions that cover up to 70 percent of their bodies.

The international study follows significant outbreaks in Louisiana, Mississippi, Alabama, Florida, Texas, and Australia. The common factor in all of these outbreaks was a sudden and drastic decrease in water salinity.

Increasingly severe storms and hurricanes are dumping unusual volumes of rain in coastal waters, and the resulting freshwater conditions can persist for months. The drop in seawater salinity is particularly extreme after intense storms like hurricanes Harvey and Katrina. As these storms become more frequent, so will the skin disease outbreaks among dolphins.

“This devastating skin disease has been killing dolphins since Hurricane Katrina, and we’re pleased to finally define the problem,” said study co-author Dr. Pádraig Duignan, Chief Pathologist at The Marine Mammal Center. “With a record hurricane season in the Gulf of Mexico this year and more intense storm systems worldwide due to climate change, we can absolutely expect to see more of these devastating outbreaks killing dolphins.”

A current outbreak of the disease is impacting the rare and threatened Burrunan dolphin in southeast Australia. The findings may provide professionals with the information they need to diagnose and treat affected animals. 

Currently, the chances of survival for infected dolphins are poor, especially for animals that experience prolonged exposure to freshwater. The disease was first noticed on approximately 40 bottlenose dolphins near New Orleans after Hurricane Katrina in 2005.

“As warming ocean temperatures impact marine mammals globally, the findings in this paper will allow better mitigation of the factors that lead disease outbreaks for coastal dolphin communities that are already under threat from habitat loss and degradation,” said Dr. Duignan. “This study helps shed light on an ever-growing concern, and we hope it is the first step in mitigating the deadly disease and marshalling the ocean community to further fight climate change.”

The research is published in the journal Scientific Reports.

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By Chrissy Sexton, Earth.com Staff Writer