Toxic algae -- add this to the long list of possible suspects in the death of a California sea otter.
As if this much beleaguered icon didn't have enough to contend with -- oil spills, toxins, parasites, sharks, and a whole host of other nemeses -- now a small number of sea otters have been shown to have died after exposure to a toxin from a freshwater algal bloom. Although the body count to this attacker stands at 21, with the population this year hovering only around 2,700, that's 21 too many.
Dr. Melissa Miller is a forensic pathologist who specializes in sea otter necropsies. When a number of otters with liver damage started to show up on her table, she set about figuring out just what the cause might be. Although freshwater algae didn't start high on her list, eventually it became the key suspect. A neurotoxin that causes liver damage was known to be produced by blue-green algae. Sure enough, the culprit was found in a Monterey County lake and was traced from its inland source all the way into the Monterey Bay and the sea otters' backyard. It's the first time a link between what we do on land and sea otter health has been firmly established.
Four of the victims were part of the Aquarium's Sea Otter Research and Conservation program (SORAC). As a result, we knew where these animals foraged, where they hung out and what types of prey preferences they had. Sure enough, field records showed that these animals did indeed spend time in the area most likely to be impacted by the flow of fresh water from the contaminated inland source, and their favorite dinner items were the ones most likely to be contaminated.
Two Aquarium staffers, veterinarian Dr. Mike Murray and field research coordinator Michelle Staedler, are co-authors of the paper, Evidence for a Novel Marine Harmful Algal Bloom: Cyanotoxin (Microcystin) Transfer from Land to Sea Otters.