Destructive invasive species spotted along San Antonio River

San Antonio River Authority crews, volunteers work to remove apple snails, egg cases

SAN ANTONIO – Apple snails are once again causing problems along the San Antonio River. The giant snails and egg cases pose an agricultural and ecological threat as they feed on aquatic plans, taking food and habitat away from the San Antonio River’s native species.

According to SARA’s website, the non-native species was first spotted in October 2019 along the Museum Reach section of the river. This time around, they’ve also been spotted in the King William area of the San Antonio River.

“(There were) about 3,600 egg cases last year, (and) we are already up to over 7,600 egg cases this year,” Shaun Donovan, Environmental Science Manager for the San Antonio River Authority said. “The amount of adult snails is three or four times more than they were in 2020. So, it’s pretty bad, and it’s just consistently getting worse from over the last couple of years.”

Staff routinely monitors the river to remove the snails and bright pink egg cases. One egg case can hold thousands of eggs.

“If we can get the egg cases out, it means that there’s not a stand of young individuals that are going to replace the older ones,” Donovan said. “The older ones (will) die out. So, it’s critically important for us to take the egg cases off as soon as we see them so that we’re not allowing for successful reproduction of the apple snails in the river.”

The spread of the snails could be detrimental to the water ecosystem.

“If they start going downstream away from the channelized areas of the River Walk and into the natural parts of the river, apple snails can eat the vegetation on the banks and they can cut back that vegetation so much that we could start having erosion along the banks,” Donovan said.

An apple snail egg case is a distinctive bubble gum pink color. One case can hold thousands of eggs. (Copyright 2021 by KSAT - All rights reserved.)
San Antonio River Authority crews and volunteers work to remove apple snails and egg cases. (Copyright 2021 by KSAT - All rights reserved.)

So, how did this invasive species get here? It could be as simple as someone dumping their aquarium into the river. Now, volunteers are needed more than ever to monitor, collect and safely dispose of apple snails.

“We have our staff at the River Authority go out and remove the snail egg cases. We have a consultant company that goes out every every 10 days (to remove the egg cases),” Donovan said. “But it’s just the more people, the better. Volunteers come out (to the river) every single day, and they can cover a larger area. So, volunteers are critical for this effort.”

If you spot any apple snails or egg cases, you can report them at (866) 345-7272 or online with as much detail as possible.

About the Authors

Alicia Barrera is a KSAT 12 News reporter and anchor. She is also a co-host of the streaming show KSAT News Now. Alicia is a first-generation Mexican-American, fluent in both Spanish and English with a bachelor's degree from Our Lady of the Lake University. She enjoys reading books, traveling solo across Mexico and spending time with family.

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