Sea lions are in big trouble. The past few years have seen a record number of stranded creatures on the West Coast showing up underfed and confused in increasingly strange places. Through May, strandings for the year were more than 10 times the average over the preceding decade.
Scientists have largely blamed the uptick on warming waters, which may make food more scarce in the usual foraging areas. But a study published Monday in Science presents another tragic factor: Sea lions are increasingly exposed to a neurotoxin that hurts their spatial memory, making them prone to getting confused and lost while searching for increasingly rare sources of food.
The neurotoxin isn’t manmade — it’s produced naturally by marine algae and amplified by tiny creatures that consume it — but we might still be to blame for the plight of sea lions, and perhaps for the deaths of countless other marine mammals. The algal blooms that produce this toxin, called domoic acid, flourish under the warmer waters brought about by climate change.
