Researchers in California have discovered an ancient variety of cyanobacteria that could be one of several things killing playful Southern Sea otters faster than they can reproduce.
Melissa Miller, a state wildlife veterinarian has been investigating the recent rapid decline in among otters over the past two years. According to the U.S. Geological Survey, only 2,711 otters remain in Central and Southern California waters.
Miller’s first clue that something strange was attacking the otters came in 2007. That year, nearly a dozen otters showed up dead in Monterey Bay.
Upon examination, she discovered the animals were jaundiced, with bright yellow gums and yellow in the whites of their eyes. During autopsy, Miller found swollen livers that fell apart in her hands.
Tests for all the usual bacterial infections came up negative, so Miller was forced to dig deep into her veterinary knowledge to come up with an explanation.
According to the LA Times, Miller remembered that the damaged livers were like those of a dog or a cow that died after drinking out of a scum-choked farm pond. The culprit in those cases was a toxin, microcystin, produced by a type of cyanobacteria called Microcystis.
Her suspicions were confirmed when the California State Water Quality Control Board informed Miller that Microcystis blooms seemed to be occurring more often in lakes and estuaries; one of which was where the deceased otters had been found.
Diseased Oceans Are Deadly Habitats
The reemergence of cyanobacteria, an ancestor of modern-day bacteria and algae, is part of global trend that scientists attribute to the buildup of pollution and nutrients in oceans and fresh water supplies. This contamination is thought to be a consequence of expanding agriculture and the modern industrial society.
Aside from providing the perfect breeding ground for hostile cyanobacteria, marine pollution is causing ocean dead zones all over the world, especially near areas heavily populated by humans.
Devoid of the oxygen needed to support vibrant marine life, these dead zones cause reproductivity problems in marine organisms by decreasing the size of reproductive organs, number of eggs and spawning activity.
Image Credit: Flickr - Mike Baird