Thousands of dead or critically ill dolphins and sea lions have been found along California’s southern coast in the past month. About 200 have been reported each day, mostly concentrated in Santa Barbara and Ventura counties in the southern Golden State.
An impressive die-off, and one that experts say may have something to do with climate change. In fact, the direct cause of the carnage appears to be the seasonal bloom of toxic algae that produce domoic acid-a potent toxin that once ingested by animals causes their disorientation and convulsions.
Harmful algal blooms act by poisoning the food chain, explained David Caron, professor of biological sciences at the University of Southern California. Creatures such as crustaceans, anchovies and sardines in fact consume the toxins before they in turn are devoured by larger marine mammals. “Larger marine mammals feed on these highly toxic fish and become poisoned in turn, and if they consume enough of them they can be killed, as is happening now,” the academic said.
But even humans are not immune from the risk. Although the California Department of Public Health constantly monitors levels of toxic algae in the waters, swimmers can get sick if they ingest seafood contaminated with the toxins. In addition, poisoned animals may perceive humans approaching to help them as hostile presences, attacking them.
The advice, therefore, is to turn to rescue groups, which so far have managed to pull some animals to safety by providing them with fluids to keep them alive until they can flush the poisons from their systems.
According to experts, algae typically bloom in California between March and June, but this year’s prolonged wet winter may have forced a delayed bloom. What’s more, rising water temperatures caused by climate change have greatly expanded the habitat for these harmful algae, which not surprisingly tend to form in warmer waters.
