Toxin clouds sea-lion memory

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Toxic algal blooms could be impairing the memory and navigation of California sea lions (Zalophus californianus), possibly interfering with how they forage.

Kendra Hayashi Negrey

Domoic acid is a naturally occurring neurotoxin that is released by certain algae (such as Pseudo-nitzschia species, pictured). It is known to damage the hippocampus, a key memory centre in the brain, but its effects on behaviour have been unclear. Between 2009 and 2011, Peter Cook, now at Emory University in Atlanta, Georgia, and his team studied 30 wild sea lions that were undergoing veterinary rehabilitation off the California coast. Using magnetic resonance imaging, the team found that animals with greater neurotoxin damage to the upper right portion of the hippocampus performed worse than animals with less-damaged brains on several spatial memory tasks, such as recalling the location of a bucket of fish.

Because these animals rely heavily on foraging, the toxin could affect their survival in the wild, the authors say.

Science 350, 15451547 (2015)

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