CHRON reported first: Texas boaters appear almost certain to be drafted as combatants in a battle aimed at slowing spread of zebra mussels, an invasive mollusk that can cripple inland fisheries and already has cost Texans more than $300 million because of its effects on crucial water supply infrastructure. The Texas Parks and Wildlife Commission will next month consider adopting regulations mandating boaters approaching or leaving reservoirs, rivers or other public freshwater anywhere in the state drain and dry all water from their boat, live wells, bilges, motors, bait buckets and any other water-holding receptacles or face a citation carrying a fine of as much as $500.
Odds are good the commission will adopt the proposal that would expand “clean, drain and dry” rules recently put into place in 47 counties to all of Texas’ 254 counties. Members of the commission, which sets policy for the Texas Parks and Wildlife Department, earlier this year instructed agency staff to develop the proposal.
Devastating effects
The move to mandate the draining of water from boats before and after launching on freshwater targets the most common way zebra mussels are spread: boaters’ transporting the invasive mollusks from an infected water body to non-infected waters.
Boaters on water bodies infected with zebra mussels can, unintentionally, end up with water containing microscopic larvae (veligers) in their vessels’ bilge, live wells, bait buckets or even outboard cooling systems. Those larvae, which are able to survive long periods in the trapped water, can be released days or weeks later when the boat is launched into another water body.
“Transporting veligers from infected waters to non-infected waters appears to be the most common vector for the spread of zebra mussels,” said Ken Kurzawski, director of information and regulations for TPWD’s inland fisheries division.
The effects of resulting infestations can be environmentally and economically devastating.
Zebra mussels, native to Russia, were first discovered in North America in the Great Lakes region in the late 1980s, suspected to have arrived in ballast water of commercial ships.
With no natural enemies in their new home, the small mussels – individuals are about the size of a fingernail – exhibit explosive growth; a single mussel produces about 1 million eggs a year, and populations grow to billions of mussels within a year or less. Zebra mussel populations in infected waters grow so high and so quickly that the mollusks coat most exposed hard surfaces, clog water pipes and other water transportation infrastructure, outcompete native species, alter ecosystems, and even change the chemical composition of water.
The mussels remove massive amounts of calcium from water, using it to build their shells. Even more damaging to freshwater ecosystems, the billions of mussels hog food crucial to survival of native species.
“Zebra mussels are filter feeders, and they take a good chunk of the available productivity out of the water,” Kurzawski said. “They feed on plankton that are the crucial nutrients for a lot of native species – things such as shad and other forage fish.”
The significant reduction of plankton rattles all the way up the food chain, resulting in smaller and less healthy fish populations.
The mussels don’t just negatively affect ecosystems, they wreak havoc on pipes, pumps and other water control/management structures, resulting in an economic toll that, in Texas, already has reached hundreds of millions of dollars.
Rapid spread
Zebra mussels, which have spread to 30 states and proved impossible to eradicate once they are established in a water body, found their way to Texas less than a decade ago. And they arrived the way almost all such invasives do – in or on a boat or boat trailer.
Their Texas invasion began on Lake Texoma, the border-straddling reservoir on the Red River, where they were discovered six years ago. They have since spread – almost certainly through being transported by boaters – to five other reservoirs in north-central and central Texas: Ray Roberts, Lewisville, Bridgeport, Belton and Lavon. Water samples from lakes Fork, Tawakoni and Grapevine have detected zebra mussel DNA, but adult mollusks have not been documented.
The infestation on Texoma has resulted in the biggest economic impact the mussels have had on Texas so far. The North Texas Municipal Water District, which provides water for 1.6 million Texans, was forced to construct a new 46-mile pipeline and other infrastructure to transport and treat water from zebra mussel-infested Lake Texoma. That project cost $300 million and resulted in a 14 percent jump in customers’ water rate.