Algae near sea lions is causing sickness and wreaking havoc as it disrupts marine life along the Pacific Coast. The sea lions are losing their memory because of a toxin, and the mammals have lost their ability to navigate, according to Reuters.
The algae was discovered by Scientists after finding the microscopic culprit that has disrupted marine life. While the sea lions have been sick, it’s also been destroying Northern California’s delicious supply of Dungeness crab.
Researchers led by a UC Santa Cruz team illuminates the relationship between damage to the brain and mammals profound loss of memory and navigational skills. In recent years, biologists have increasingly observed a high number of the mammals struggling on beaches, weak, confused and trembling.
“They have a lot of difficulty navigating and finding food,” said Peter Cook, who presented the findings Monday at the biannual Conference on the Biology of Marine Mammals in San Francisco. “They have no sense of which way to go.”
While the harmful sea lions’ algal blooming near the animals are not unusual, this year’s phenomenon was the largest ever recorded, lasting through the summer and extending from Santa Barbara to Alaska. Blooms of the toxic algae typically occur in the spring and last just a few weeks.
This year’s algae near the sea lions caused the unprecedented shutdown of the commercial Dungeness and rock crab fisheries throughout most of California. But the toxin has affected other marine life as well, working its way up the food chain from razor clams to anchovies and other small fish to sea lions, one of the top predators in coastal waters.
For the first time ever, sick sea lions have been documented in Oregon and Washington, not just California, said Kathi Lefebvre, of the Northwest Fisheries Science Center, part of the National Oceanic and Atmospheric Administration.
An estimated one-third of stranded sea lions suffer from domoic acid poisoning, Cook said. The algae research is published in this week’s issue of the journal Science.
Using dog crates and a truck, the team picked up 30 California sea lions undergoing veterinary care and rehabilitation at the Marine Mammal Center in Sausalito. Some had poisoning, while others had infections or other physical ailments.
The sea lions were delivered to a psychology lab at UCSC, where their healing continued and they underwent behavioral tests.
Animals with healthy brains were able to quickly master the pattern of a maze and adjust to last-minute changes in its route. In contrast, animals with poisoning lacked the short-term memory to recall or adapt to the changed maze.
They showed differences in long-term memory as well, with poisoned animals incapable of remembering where buckets of fish were hidden because of the algae.
Magnetic resonance imaging showed the poisoned animals had a damaged and shrunken hippocampus, a region of the brain responsible for memory and navigation. The greater the damage, the worse their skills.
The study “has very profound implications for an animal that to survive has to forage,” said Lefebvre, who was not involved in the work. And it could eventually help in the diagnosis of humans poisoned by domoic acid, she said. Human cases are rare but may rise if warming ocean temperatures continue to support toxic algal blooms.
“If we continue to see increasing concentrations in the food web, we’re going to need to be more vigilant to protect human health,” said Lefebvre, adding that research by Cook and others could provide “a learning tool for studying the effects of domoic acid in not only marine mammals but also humans.”
The algae has put 3,400 sea lions into the state’s rehabilitation facilities between January and June — and the final tally, still being calculated, will likely surpass 4,000 animals, said Justin Viezbicke, the California stranding coordinator for NOAA fisheries. Additional animals likely died out at sea.