Invasive zebra mussel species discovered in Lake Austin

Sarah Bloodworth

Lake Austin is positive for Dreissena polymorpha, otherwise known as zebra mussels. According to Texas Parks and Wildlife Department, zebra mussels are invasive freshwater mussels that reproduce quickly and have major environmental and economic impacts.

In early August, biologists found zebra mussels in the marina of Lake Austin near the Walsh Landing boat ramp.

According to Monica McGarrity, the Texas Parks and Wildlife Aquatic Invasive Species team leader, zebra mussels spread by either passively floating downstream or by attaching to objects such as boats.

“It is impossible to say whether zebra mussels were spread passively to Lake Austin ­— passively meaning that the larvae float downstream in the water and settle on hard surfaces — or whether they were actively moved by a boat,” McGarrity said.

Zebra mussels are considered invasive because they disrupt the ecosystem by creating major competition for microscopic plants called plankton. According to Marcos De Jesus, a Texas Parks and Wildlife Fisheries biologist, zebra mussels reproduce very rapidly, so when introduced into the food chain, they consume large quantities of plankton that many species rely on.

“Plankton is the base source of the food web, so competing with zebra mussels can create a big impact,” De Jesus said.

Zebra mussels can also clog pipes, which could disrupt Austin’s water supply. According to De Jesus, zebra mussel infestations are known to increase utility bills as they damage pipelines and waterways.

 “We only found four zebra mussel individuals … the fisheries don’t seem to have an impact negatively that we can determine right now,” he said.

According to McGarrity, there is not yet evidence that the lake is infested, which would mean that there are reproducing populations of the species. However, Lake Travis was designated infested with zebra mussels in June this year.

“We found a single zebra mussel larva and several adults,” McGarrity said. “However, more mussels may have been present. We haven’t yet found evidence that they are fully established in Lake Austin and reproducing successfully.”

Complete eradication of zebra mussels is near impossible, but Texas Parks and Wildlife Department will continue to encourage the community to report any sightings of zebra mussels and to prevent infestation by properly cleaning, draining and drying boats.

“People need to become educated and stay aware,” De Jesus said. “This is the first time we’ve seen them this far south, so we aren’t exactly sure how they are going to react to the environment … only time will tell.”