Zebra mussels can attach to almost any hard surface, including boat motors. Photo courtesy of Texas Parks and Wildlife Department
EDITOR DANIEL CLIFTON
LAKE TRAVIS — One measures less than an inch, but when they mass together, these invasive creatures can cause big damage. Texas Parks and Wildlife Department officials confirmed zebra mussels have invaded Lake Travis.
“Well, it’a a big concern, first, because it’s an invasive species,” said Marcos De Jesus, the TWPD San Marcos-Austin fisheries management district supervisor. “It’s definitely something to worry about.”
On June 22, the Texas Parks and Wildlife Department and the Lower Colorado River Authority confirmed the infestation of zebra mussels in Lake Travis. Officials said a staff member of a Lake Travis marina spotted a single zebra mussel attached to an outboard motor of a boat moored on the lake. Biologists found more of the invasive species on other nearby boats and submerged parts of the marina.
Through further investigation, biologists also discovered juvenile and adult zebra mussels on two other sites in Lake Travis. This, officials said, indicates an “established, reproduction population.”
De Jesus described the Lake Travis inhabitation as “disheartening.”
“We’ve worked so hard at educating people at how to, at least, slow the spread of these through lakes and around the state,” he said.
Though zebra mussels only grow to a maximum size of 1½ inches, it’s the sheer volume of the Eurasian native that concerns biologists. De Jesus pointed out that once the species gains a hold, it can pack thousands, even millions, into a very small space on hard surfaces. This causes issues for any underwater infrastructure such as water intake pipes and can even clog up boat motors.
Zebra mussels can take over a shoreline, and with their jagged-edged colony, it becomes difficult for people to use the infected area, De Jesus said.
Other concerns revolve around the impact on the ecology of infested lakes and waterways.
“They’re filter feeders,” De Jesus said. “They’ll filter water through themselves and take out nutrients and plankton, which fish depend on. They change the ecology of the lake.”
The longterm effects are yet to be determined.
With an established, reproducing population in Lake Travis, it’s inevitable the species will spread downstream to Lake Austin and Lady Bird Lake as well as the lower stretches of the Colorado River, but the remaining Highland Lakes upstream of Lake Travis aren’t in danger — yet.
De Jesus said that the same manner in which zebra mussels made it to Lake Travis will likely be how they end up in the upper Highland Lakes.
They’ll hitch a ride.
The microscopic Zebra mussel larva usually gets transported from one body of water to another by boats. De Jesus pointed out that when a boater takes their watercraft out of a lake, some of the water comes along for the ride. The water can even get onto the boat trailer.
If the water has zebra mussel larvae in it and the boater uses their craft on an uninfected lake without taking the necessary precautions, they’ve then introduced zebra mussels to that lake.
“Boats are the main vector for zebra mussels,” De Jesus said.
The Texas Parks and Wildlife Department, the Lower Colorado River Authority, and other officials and concerned groups have stressed the importance of preventing the spread of zebra mussels. It comes down to three things, De Jesus said.
“We stress to people: Clean, drain, and dry your boat when you take (it) out of the lake,” he said. “You can’t just drain the boat and that’s it. You have to clean it, all of it to get any water out, and dry it. It you don’t clean, drain, and dry your boat, you risk the chance of spreading these things.”
He emphasized doing the three-step process for any boat, boat gear, and even the trailer if it comes in contact with the water.
Zebra mussels are native to Eurasia, specifically Russia, and first showed up in the United States in 1988 when they were identified in Lake St. Clair, located between Michigan and Ontario, Canada. The invasive species has since spread across a number of states, most recently Texas, California, and Utah.
According to the Texas Parks and Wildlife Department, zebra mussels have infested 11 Texas lakes across five river basins as of June 22. This means the species has established, reproducing populations. The lakes are Belton, Bridgeport, Canyon, Dean Gilbert, Eagle Mountain, Lewisville, Randell Lake, Ray Roberts, Stillhouse Hollow, Texoma, and now Travis.
“Once they get in a lake, they are hard to control and a big problem,” De Jesus added. “The best way is try and prevent them from spreading. You do that by clean, drain, and dry.”