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Zebra mussel larva confirmed in Lake Bridgeport

By Bob Buckel | Published Saturday, June 29, 2013

”We knew it was coming. It was just a matter of time.”

Zebra mussel larvae have been confirmed in Lake Bridgeport just days after the discovery of the invasive exotic in Lewisville Lake.

The Texas Parks and Wildlife Department issued a news release Thursday confirming the discovery of zebra mussel “veligers” or larva in water samples collected June 6 by the Tarrant Regional Water District. Using cross polarized light microscopy Dr. Bob McMahon with The University of Texas-Arlington confirmed those results on June 17.

Prevention

PREVENTION – Fishing guide Keith Bunch washes his boat after pulling it out of Lake Bridgeport Friday. The spread of zebra mussels can be slowed by making sure boats that operate in infested waters are not used in another body of water until they have been cleaned, drained and dried. Messenger photo by Joe Duty

“It’s like having chicken eggs but no chicken,” Chad Lorance, spokesman for TRWD said. “We haven’t found any settled juvenile or adult zebra mussels in the lake, but it’s very unlikely that we don’t have them in Lake Bridgeport.”

Earl Smith, Decatur’s director of public works, said the water district called City Manager Brett Shannon Tuesday and let him know about the discovery.

“There’s no visible sign yet, so there’s not any quality issue with drinking water at this time,” Smith said.

Decatur, Bridgeport and Runaway Bay all get their municipal drinking water supply from Lake Bridgeport.

Given the high mortality rates of zebra mussel veligers, the TRWD release stressed that there’s no guarantee an adult population exists – but it added, “Given these results and the DNA results from the past two years, it is likely that the lake is infested.”

An Infestation

AN INFESTATION – Zebra mussels are about the size of a quarter. Although an adult population has not been confirmed in Lake Bridgeport, Tarrant Regional Water District representatives said it is likely. Courtesy of the United States Geological Survey

Lake Bridgeport has showed zebra mussel DNA the last couple of years, and as a result, the water district has stepped up its testing program, Lorance said.

Routine monitoring by TRWD, UTA and Texas Parks and Wildlife will continue on the lake to determine if there is any growth or spread of the mussels. And because Eagle Mountain Lake and Lake Worth are downstream, they are also at risk and will continue to be monitored.

Zebra mussels have both an economic and a recreational impact, as they can clog intake pipes, harm boats and motors, annoy boat-dock owners and make water recreation hazardous.

On boats, the mussels can cover hulls and clog water-cooling systems. At full strength they tend to completely cover anything left underwater and because of their razor-sharp edges, they can injure swimmers.

Smith said where he previously worked, with the City of Paris, they dealt with the zebra mussel infestation in their water source, Pat Mayes Lake, and it was a major problem.

“We tried all kinds of stuff,” he said. “It became a taste and odor problem with the water, and we were not successful with it. I may call them and do some research to see if they’ve come up with anything.”

The zebra mussels are prolific, he said, and create a real problem for water customers.

“We had to take the intake structures out of service, just go in there and clean it,” he said. “It was a mess. It’ll reduce the diameter of the pipes and increase resistance, which raises your pumping costs. It’s a terrible problem.”

From an environmental perspective, zebra mussels are filter feeders, which mean they compete with baitfish such as shad for available forage. Any impact on baitfish can affect their predators – game fish such as bass, striped bass and catfish. Zebra mussels are also harmful to the native mussel population because they will colonize on their shells and essentially suffocate them.

Their spread can be slowed by making sure boats that operate in zebra mussel-infested waters are not used in any other body of water until they have been cleaned, drained and dried.

TPWD has adopted rules regarding the transfer of zebra mussel larvae in water from lakes Texoma, Lavon, Ray Roberts and Lewisville. To comply with these rules, boaters and anglers need to drain all water from their boats (including live wells) before leaving those lakes.

TPWD and a coalition of partners have been reaching out to boaters in Texas with an advertising campaign to educate them not to transport the tiny mussels or their microscopic larvae, which are invisible to the naked eye and can stay alive inside livewells, bait buckets and other parts of the boat for up to a week. TRWD, the North Texas Municipal Water District, Trinity River Authority, City of Dallas Water Utilities Department, Upper Trinity Regional Water District, Sabine River Authority, Canadian River Municipal Water Authority, San Jacinto River Authority, Brazos River Authority, City of Grapevine, City of Houston, City of Waco and Lady Bird Johnson Wildflower Center have all partnered in that effort.

Originally from the Balkans, Poland and the former Soviet Union, zebra mussels found their way to the Americas in the 1980s via ballast water of a ship. The small invaders were first found in 1988 in Lake St. Clair, Mich., and are currently known to have infested 29 states and more than 600 lakes or reservoirs in the United States.

Anyone wishing to receive a supply of informational brochures, wallet cards or posters about zebra mussels to distribute to boaters around lakes Bridgeport, Lewisville, Ray Roberts or Texoma may contact marketing@tpwd.state.tx.us. For more information regarding zebra mussels visit www.texasinvasives.org.

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