In 2005, scientists began to notice a peculiar skin condition in coastal dolphin populations, one that was soon found to cover as much as 70 percent of their bodies and could prove fatal. A new study has found the increasing frequency and severity of storms as a result of climate change to be a key factor in this novel disease, by drastically altering the salinity of the waters the animals inhabit.
Climate change is reshaping the Earth’s weather systems and strengthening storms are one consequence of this new world we live in. Studies have shown how increasing heat in the upper layer of the ocean is contributing to more powerful hurricanes, while reports from the World Meteorological Organization have demonstrated how extreme weather events like cyclones and heavy rainfall are gaining in frequency across the globe.
One byproduct of this is the dumping of massive amounts of freshwater in otherwise salty waters, which causes rapid and significant decreases in salinity that can linger for months at a time. For dolphins that inhabit coastal areas, this means a sudden shift to foreign and unfavorable conditions, though scientists had not been able to draw a link between these climate change-related events and the well-being of the dolphins.
That was until a pair of recent and very similar mortality events took place in Australia across two different populations of coastal dolphins, from which some distinct parallels could be drawn. Both groups of cetaceans exhibited patchy skin and lesions covering up to 70 percent of their body, bearing fungal and bacterial species and discoloration. Both outbreaks followed an “abrupt and marked decrease in salinity” due to rainfall in nearby catchments, with the conditions lasting from weeks to months.
This combination of pathology and environmental factors enabled the authors of the new study to create the first-ever case definition for so-called freshwater skin disease, and establish what they say is a link between the condition and climate change. The hope is that the research can better help professionals diagnose and treat dolphins impacted by the condition, which they anticipate will only become more common.
“This devastating skin disease has been killing dolphins since Hurricane Katrina, and we’re pleased to finally define the problem,” says study 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.”
The research was published in the journal Scientific Reports.
Source: The Marine Mammal Center
