Quagga mussels (Dreissena bugensis) have invaded Southern California, infesting two dozen lakes, reservoirs and Colorado River stations! San Justo Reservoir in Central California is closed to public use because it is infested with their cousins, the zebra mussels (D. polymorpha). The mussels proliferate rapidly via swimming “veliger” larvae that settle on every available surface and grow into adults that typically reach the size of fingernails. They can pile up layer upon layer until they clog pipes up to 2 feet in diameter. To sustain this growth, mussels strip plankton from the water, denying food to other species and causing fisheries to collapse.

Quaggas were introduced into Lake Mead on the Colorado River a few years ago, spreading down the river, into the Colorado Aqueduct and eventually to lakes and reservoirs. The Metropolitan Water District of Southern California spends $10 million/year to clean adults from their water delivery systems and reduce the amount of veliger larvae in the water.

Mussels can also be spread by boats, clinging to underwater surfaces and in pockets of water in cooling systems, bilges, etc. The California Department of Fish and Game and California Department of Boating and Waterways are providing educational resources for boat owners and many lake managers are operating boat inspection and decontamination stations with an eye to preventing them from spreading to new area.

On February 1^st and 2^nd of this year, the UC Division of Agriculture and Natural Resources and the UC Sea Grant program convened a workshop in San Diego on control and eradication strategies for quagga and zebra mussels. Water managers, agency staff and research scientists from California to Virginia and Canada met to learn about 8 control and eradication strategies. The strategies included: hand removal, covering with tarps to expose mussels to chemicals in a contained situation, types of chemicals used for mussel control, molluscicide derived from a micro-organism, fish bio-control, UV light and seismic technologies, pH manipulation, and integrated pest management.

The participants also met in discussion groups to identify information, equipment, supplies, staff, etc. that they would need to use each method. A second round of discussion groups focused on sharing information and considering how they could collaborate within geographic regions of California, as well as working with partners from Arizona and Nevada. During visits to lightly and heavily infested reservoirs, workshop attendees learned how to find mussels by touch and visual cues.

We will be developing new research and education programs to assist in efforts to control and eradicate invasive mussels. One research project in which we are collaborating is to test how to enhance the ability of resident fish to clean mussels off water facilities in lakes. Future blogs will report on our new program in invasive mussel control.