Sea otters poisoned by freshwater toxin

A recent study links at least 21 Southern sea otter deaths to freshwater contamination by a toxin called microcystin, marking the first connection between the toxin and the death of marine mammals, according to a California Department of Fish and Game press release.

DFG and UC Santa Cruz scientists found high concentrations of the toxin in lakes and rivers that flow into the Monterey Bay, where 17 of the otters were found. The toxin is a product of the bacteria Microcystis (a harmful type of blue-green algae) and flourishes in warm, nutrient-rich waters.

The toxin apparently lodges itself in the tissue of shellfish, which are eaten by sea otters, and appears to cause liver failure and other damage to the otters. The DFG/UCSC study also suggests that humans also may be at risk from microcystin poisoning if they consume shellfish caught near river mouths.