A toxin produced by marine algae in San Francisco can impair sea lions’ memory, making it difficult for sea lions to find their way to food, a new study reveals. Large growths of the algae off the coast of California may have contributed to the record-breaking number of starving sea lions that have washed up on the state’s many beaches in the past four years. The algal toxin is believed to affect sea lions, dolphins, fur seals, sea otters, and other species as well. Sadly, the problem is unlikely to go away anytime soon, especially with warming ocean waters and agricultural runoff fueling outbreaks.
“The blooms are just going to get bigger and bigger,” Peter Cook of Emory University, who reported the behavioral effects of domoic acid, told National Geographic. “Sea lions are just the tip of the iceberg. It’s a grim story.”
Sadly, algal blooms are becoming more and more common in many areas of the ocean—particularly in the Pacific. Certain types of algae produce neurotoxins that accumulate up the food chain, finding their way into fish and anything that consumes them.
A study published in Science reveals that many of the sea lions washing up on the shores suffer from brain lesions caused by a toxin produced by a specific type of algae. The lesions originate in the hippocampus, an area of the brain involved in memory. The affected sea lions have impaired spatial memory and trouble navigating their surroundings.
In the study, the researchers conducted MRIs on 30 sea lions and found those with lesions struggled to remember where food was placed in an enclosure. Other tests showed signs of impaired short- and long-term memory. The research is the first to show the behavioral effects of long-term exposure to toxins in a large marine animal. Scientists suspect that other large creatures may be impacted in a similar way.
“There’s almost no doubt it’s affecting other animals as well,” Cook says, noting that the toxin has already been measured in the blood of other species. Sea lions are the most obvious because they head to shore when they are in trouble to rest in the sun, meaning it’s easier to spot a sea lion in distress.
The specific toxin in question is domoic acid, produced by a type of algae known as Pseudo-nitzschia. This type of toxin has affected people before, most notably in a 1987 outbreak that started in contaminated Prince Edward Island shellfish. The outbreak killed three and caused illness in more than a hundred more.
The outbreaks are becoming a notable problem for the seafood industry in California. So far this year, there have been closures of anchovy, sardine, Dungeness, rock crab, mussel, clam and oyster fisheries in the state.
Source: Huffington Post, National Geographic