Fresh water skin disease (FWSD) is a disease of marine

cetacean Cetacea (; , ) is an infraorder of aquatic mammals that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel them ...

s in coastal and estuarine environments, caused when they are exposed for extended periods to water with lower than normal levels of salt (hypo-saline). It has been observed in dolphins that were displaced into freshwater lakes, and in normally-salty lakes and estuaries where salinity has dropped suddenly due to flooding or storm runoff. The symptoms are widespread skin lesions and ulcers. Circular lesions can resemble cetacean pox, which is more common in juveniles. Chronic lesions may have overgrowths of algal and/or fungal mats. Extended exposure can lead to over-hydration, electrolyte imbalance, and organ failure. The syndrome has been observed particularly with bottlenose dolphins ''

Tursiops truncatus Bottlenose dolphins are Aquatic mammal, aquatic mammals in the genus ''Tursiops.'' They are common, cosmopolitan distribution, cosmopolitan members of the family Delphinidae, the family of oceanic dolphins. molecular biology, Molecular studies ...

'' in

Lake Pontchartrain Lake Pontchartrain ( ) is an estuary located in southeastern Louisiana in the United States. It covers an area of with an average depth of . Some shipping channels are kept deeper through dredging. It is roughly oval in shape, about from west ...

, Louisiana from 2007, thought to have been trapped by

Hurricane Katrina Hurricane Katrina was a destructive Category 5 Atlantic hurricane that caused over 1,800 fatalities and $125 billion in damage in late August 2005, especially in the city of New Orleans and the surrounding areas. It was at the time the cost ...

in 2005; with '' T. australis'' at Gippsland Lakes in 2007; with '' T. aduncus'' at the

Swan Canning Riverpark Swan Canning Riverpark consists of the waterways and public foreshore reserves in the Swan and Canning Rivers in Perth, Western Australia. Established under the ''Swan and Canning Rivers Management Act 2006'', it has an area of . It is managed by ...

(

Swan Swans are birds of the family (biology), family Anatidae within the genus ''Cygnus''. The swans' closest relatives include the goose, geese and ducks. Swans are grouped with the closely related geese in the subfamily Anserinae where they form t ...

and

Canning Canning is a method of food preservation in which food is processed and sealed in an airtight container (jars like Mason jars, and steel and tin cans). Canning provides a shelf life that typically ranges from one to five years, although u ...

rivers) in 2009; and with ''T. truncatus'' in Texas following

Hurricane Harvey Hurricane Harvey was a devastating Category 4 hurricane that made landfall on Texas and Louisiana in August 2017, causing catastrophic flooding and more than 100 deaths. It is tied with 2005's Hurricane Katrina as the costliest t ...

in 2017. In the Gippsland Lakes, the sudden decrease in salinity followed a slow build-up during ten years of drought. Plaques or ulcers have also been observed in the

Chilean dolphin The Chilean dolphin (''Cephalorhynchus eutropia''), also known as the black dolphin, is one of four dolphins in the genus ''Cephalorhynchus''. The dolphin is found only off the coast of Chile; it is commonly referred to in the country as ''toni ...

(''Cephalorhynchus eutropia'') in Patagonia,

Guiana dolphin The Guiana dolphin (''Sotalia guianensis''), also known as the estuarine dolphin or costero, is a dolphin found in the coastal waters to the north and east of South America, and east of Central America. It is a member of the oceanic dolphin fami ...

s (''Sotalia guianensis'') in Brazil, and a pair of a

humpback whale The humpback whale (''Megaptera novaeangliae'') is a species of baleen whale. It is a rorqual (a member of the family Balaenopteridae) and is the only species in the genus ''Megaptera''. Adults range in length from and weigh up to . The hump ...

s (''Megaptera novaengliae'') in northern California. The histology and pathology from dolphins that died in the 2007 and 2009 Australian events was published in 2020, with the name "fresh water skin disease".

References

Cetacean diseases {{disease-stub