August 6, 2018

Invasive Snail Threatens Ecosystem of Arizona's Salt River

Apple snails were likely introduced into the river's ecosystem illegally from someone's aquarium.

apple snail shells view larger VIEW LARGER Apple snail shells, via the U.S. Geological Survey.

PHOENIX— Biologists in Arizona are trying to stop the spread of apple snails, an invasive species that could overrun the food chain on the lower Salt River, leaving native fish and wildlife with little to eat.

State and federal biologists are asking for help in containing the snails, which floaters of the Phoenix-area river can do by knocking down the bright pink egg clusters laid along the water, The Arizona Republic reported.

The snails have spread downstream and infested connected waterways since fishermen reported them to the Arizona Game and Fish Department in 2011. The South American snails were introduced in the state through the pet trade, said Jeff Sorensen, a department biologist.

"Somebody's unwanted aquarium pets were illegally introduced into the wild," Sorensen said. "And now they become everybody's problem."

The snails do not have natural predators in the state, and they eat other snails' eggs. They also easily adapt to new environments and appear to thrive in heat and drought. Their numbers are increasing.

"With the drought, as long as there's some kind of water they'll do really well," said Israel Garcia, the department's aquatic invasive species specialist. "Like much of the invasives, they out-compete the native species."

The snails lay eggs every couple of weeks in calm backwaters and river banks. A sole female snail can lay up to 15,000 eggs each year.

Sorensen hopes local predators will adapt to eat snails one day. Until that happens, biologists are chipping away at the population so native pond snails can hold on to their niche in the ecosystem. In a recent week, a crew captured 642 snails from the river and likely drowned 1.6 million eggs, Sorensen said.

While there isn't an estimate on how many snails have invaded the Salt River, it appears to be so many that eradication isn't realistic goal yet, Sorensen said.

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