U.S. West Coast Oysters Face Threat of Invasive Predator Snails

The U.S. West Coast’s native Olympia oysters face a greater threat from invasive predatory snails as climate change raises the acidity of oceans, research by the University of California, Davis found.

Predatory snails ate 20 percent more young bivalves when both species were raised in ocean conditions forecast for the end of the century, according to a university report published in the journal Proceedings of the Royal Society B. Oysters raised by the researchers under the high carbon dioxide conditions forecast for 2100 stayed smaller, while the snails were not affected and as a result ate more shellfish.

“It’s like if you go out for tacos,” Eric Sanford, professor of evolution and ecology at UC Davis and lead author of the study, was cited as saying. “If the tacos are smaller, you’re going to eat more of them.”

Olympia oysters were once so common in San Francisco Bay that they were a cheap food during the California Gold Rush, before the population collapsed from overfishing in the late 1800s, never to recover, the university wrote.

Imports of Atlantic oysters to the West Coast have introduced predatory snails such as the Atlantic oyster drill, which uses acid and a rasping tongue to make holes in oyster shells, according to the report.

Oysters are important in ecosystems because they filter water, the university said. The study shows efforts to restore oyster populations along the West Coast have been made increasingly difficult by the combination of climate change and invasive predators, it said.

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