Neuroscience links toxin to strandings
Date: December 14, 2015
Source: University of California - Davis
Brain scans and behavioral tests of California sea lions that stranded on shore show how an algal toxin disrupts brain networks, leading to deficits in spatial memory, according to a study to be published Dec. 18 in Science. The new findings by scientists at the University of California Santa Cruz, UC Davis and the Marine Mammal Center in Sausalito, Calif. suggest that chronic exposure to the toxin domoic acid, produced by naturally occurring marine algae, affects sea lions' ability to navigate in their ocean habitat and survive in the wild.
Blooms of the toxic algae typically occur in the spring and fall along the California coast, but have been increasing in frequency and severity. Hundreds of sea lions strand on California beaches every year with symptoms of domoic acid poisoning, including disorientation and seizures.
A team led by Peter Cook, then a graduate student at UC Santa Cruz and now at Emory University, studied 30 California sea lions undergoing veterinary care and rehabilitation at the Marine Mammal Center in Sausalito. Researchers administered behavioral tests to assess spatial memory and performed brain imaging (MRI) to see the extent of brain lesions in the affected animals.
Damage to the hippocampus, a part of the brain involved in memory, is often seen in sea lions with domoic acid poisoning, Cook said.
"In this study, we were able to correlate the extent of hippocampal damage to specific behavioral impairments relevant to the animals' survival in the wild," he said.
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