Natural toxin suspected in deaths of 22 dolphins
Ananova - 23rd March 2002
A naturally occurring marine toxin is suspected in the deaths of more than 20 dolphins in the US.
They have been washed ashore in Southern California since late February.
On Friday scientists collected the carcasses of three common dolphins, bringing to 22 the number found dead or dying.
"Whatever is getting them is not taking weeks; it's taking days or hours," said John Heyning, curator of mammals at the Natural History Museum of Los Angeles County.
Scientists suspect a toxin called domoic acid may be the culprit.
The stranding is the largest in Southern California since 1994, when more than 70 dolphins washed ashore during a three-month period. The cause of those deaths was never determined.
The potent toxin has never been identified as being deadly to dolphins, although it has been implicated in the deaths of other marine mammals, including humpback and blue whales. In 1998, it killed more than 400 sea lions off the California coast.
Domoic acid is produced by naturally occurring blooms of single-celled organisms of the genus Pseudonitzschia. The toxin is concentrated in filter-feeding animals, such as anchovies and sardines, which are in turn eaten by dolphins and other mammals.
The toxin also causes a human illness, amnesic shellfish poisoning, which can be deadly.