The study Fresh water skin disease in dolphins: a case definition based on pathology and environmental factors in Australia by Pádraig Duignan and Kate Robb of the Marine Mammal Foundation and Nahiid Stephens of the School of Veterinary Medicine at Murdoch University said that climate change is a growing threat to coastal and estuarine dolphin populations, with extreme weather events affecting their habitats, potentially culminating in dolphin fatalities.
For the first time, we were able to fully characterize the lesions and provide a case and extent of disease definition based on two of these Australian mortality events. Although these events are historic, they allowed to conduct post mortem analyzes on dolphin carcasses to identify the cause of the their death.
Scientists said: "In the same year as the Gippsland Lakes outbreak, a similar outbreak was first reported in US waters when bottlenose dolphins suffered what is now believed to be was FWSD in Lake Pontchartrain, Louisiana following Hurricane Katrina in 2005.
We found that FWSD occurs when a sudden and steep drop in salinity occurs within a few days, with hypo-saline conditions that persist for a number of subsequent weeks or months.
Climate change threatens Australian dolphins
Salinity is reduced following a sudden and significant influx of fresh water, usually following heavy rainfall, often after a period of relative drought.
We have been fortunate that the dolphin populations in Australia were well documented by long-term and ongoing studies on ecology, population and behavior in the field that have provided crucial contextual information. Why Ulcerative skin lesions are similar to severe third-degree burns and often affect a large percentage of the body surface.
Secondary infections also play a role. In Western Australia, unusually high winter-spring rainfall in river basins transformed a normally marine / brackish habitat into freshwater. All events have in common a previous extreme weather event, which is predicted to increase in frequency and severity with climate change.
Based on these findings, we are concerned that freshwater skin disease is an emerging disease in cetaceans that we will likely see globally increasing in frequency in vulnerable estuaries and coastal habitats that continue to be impacted by worsening climate change.
We are working hard to understand the complex nature of this disease. We regularly monitor dolphins in the lakes and more recently we have recorded around 80% of them with skin lesions. 6 dolphins died and we saw others in poor condition.
We don't know why this is happening, but it could be linked to heavy rains after the fires that wiped out sediments in the lake system. This is a distressing situation and we are concerned about the welfare of the affected dolphins. We are looking for options to minimize the impacts of this disease on animals."