Origin: Native of Russia
Impact: The zebra mussel is a highly invasive, small freshwater mussel that multiplies rapidly and can cause tremendous environmental and economic damage. Their larvae are microscopic, and the adults are usually less than 1 1/2 inches long. Zebra mussels are usually found in large clusters, have a salient zebra-like striped pattern on their shells, and lie flat on a smooth surface, unlike many other mussels. According to the online National Atlas of the United States, "Once zebra mussels become established in a water body, they are impossible to eradicate with the technology currently available."
The spread of zebra mussels: Originally from the Balkans, Poland and the former Soviet Union, zebra mussels are firmly established in Europe and have invaded much of the U.S. On April 3, 2009, the first adult zebra mussel in Texas waters was confirmed in Lake Texoma. Zebra mussels have spread rapidly from the Red River basin to the Trinity Brazos, Colorado, and Guadalupe river basins.
Fourteen Texas lakes across five river basins can be classified as "infested" with zebra mussels, meaning that the water body has an established, reproducing population: Austin, Belton, Bridgeport, Canyon, Dean Gilbert (a 45-acre Community Fishing Lake in Sherman), Eagle Mountain, Georgetown, Lewisville, Livingston, Randell Lake (access for Denison residents only), Ray Roberts, Stillhouse Hollow, Texoma, and Travis. Zebra mussels or their larvae have been detected on more than one occasion in these water bodies but so far there is no evidence of a reproducing population: Fishing Hole (a small lake connected to the Trinity River below Lake Lewisville), Grapevine, Lavon, Richland-Chambers, Waco, Worth, Red River below Texoma, portions of the Trinity River, Leon and Little Rivers below Belton, and Lampasas River below Stillhouse Hollow. Zebra mussels or their larvae have been found once in recent years in Lakes Fork, Lady Bird, and Ray Hubbard, and in the Colorado River downstream of Austin, and therefore these water bodies are classified as "suspect". (See map) Several lakes, as well as rivers downstream of newly-infested lakes, are now considered "Inconclusive" due to recent DNA-only detections.
Experts fear they could spread to many other water bodies in Texas; biologists with Texas Parks and Wildlife Department and partners are monitoring many high-risk water bodies in Texas for the presence of zebra mussels.
If you have spotted Dreissena polymorpha (Zebra Mussels), use this report form to send an email to the appropriate authorities.