Marching on — Zebra mussels in another Texas lake

aaamusslesLike fire ants, a new pest is quickly marching across Texas, albeit by water instead of land.

Zebra mussel larvae, known as veligers, have been confirmed in Lake Bridgeport. The news comes days after the discovery of the invasive exotic in Lewisville Lake.

A zebra mussel population is suspected in Lake Bridgeport because zebra mussel DNA was found in the fall of 2011 and 2012, and some veligers were detected this spring in plankton tows.   Samples collected by the Tarrant Regional Water District from Lake Bridgeport on June 6 were examined using cross polarized light microscopy and suspect veligers were detected.  Dr. Bob McMahon with The University of Texas-Arlington confirmed these results on June 17.

It is important to note that to date no settled juvenile or adult zebra mussels have  been found in Lake Bridgeport to suggest a self-sustaining population.  Given the high mortality rates of zebra mussel veligers it’s not a guarantee that a population exists but given these results and the DNA results from the past two years it is likely that the lake is infested.

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

Zebra mussels can have economic and recreational impacts in Texas reservoirs. They can clog public-water intake pipes, harm boats and motors left in infested waters by covering boat hulls and clogging water-cooling systems, annoy boat-dock owners by completely covering anything left under water and can make water recreation hazardous because of their razor-sharp edges.

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

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