Evaluation of the Impact of Ultra-Violet Light Treatment on Quagga Mussel Veligers at Davis Dam
An experimental UV unit has been installed at Davis Dam for the treatment of quagga mussel veligers. The UV treatment will initially be evaluated by RNT Consulting Inc., who will determine if the treatment eliminates downstream settlement of quagga mussel veligers. After this research is conducted, it will be beneficial for Reclamation to determine the treatments mode of action on the veligers. Can the effects of UV treatment on quagga mussel veligers be detected immediately after exposure, or is there a delayed effect? Are all veliger life stages/size classes equally impacted by the treatment? Does UV treatment prevent settlement by causing immediate or delayed mortality, physical damage, behavior modification, and/or genetic mutation?
Need and Benefit
Invasive mussels are aggressive biofoulers which pose a significant threat to Reclamation's dams and structures. Quagga mussel infestations have already caused loss of cooling capacity, lower water pressure, and flow restrictions at Hoover, Davis, and Parker Dams. Conventional treatment methods such as chemical oxidant treatment (chlorine) are costly, environmentally adverse, and require discharge permitting. Consequently, there is a need for innovative treatment methods and technologies that will prevent or limit mussel colonization in such facilities. Reclamation has been working to develop a variety of control techniques, but a completely effective treatment has yet to be deployed. Ultra-violet (UV) light irradiation has shown promise in several preliminary studies. Reclamation facilities would be particularly interested in UV treatment for mussel settlement because it does not require discharge permitting and has no detrimental effects to the environment.
Several UV irradiation studies have been conducted for the prevention of the settlement of quagga mussels, but treatment effectiveness is dependent on site specific characteristics such as water transmittance, suspended solids and installation location. Effectiveness also depends on achieving the correct UV dose (dose=intensity × exposure time). After testing the effectiveness of the Davis Dam UV unit at preventing veliger settlement, it is important to determine the treatments mode of action. Little is known about how UV exposure directly impacts mussels. This knowledge will improve our understanding of the UV treatment so that it can be applied to other situations where mussel control is of importance. The knowledge gained from this research may also assist to advance the development and analysis of new and unique mussel treatments. Determination of the genetic damage produced by UV may provide significant insight into the development of novel treatments that can directly target genes responsible for settlement and mortality.
The results of this research will be presented in a technical memorandum which will describe the effect of UV exposure on quagga mussel veligers. The report will provide a detailed description of the impact of UV exposure on veliger behavior, damage, mortality, and DNA damage. If warranted, the results of this research will be published so that the information can be used to develop, test, and implement UV treatment for the prevention of invasive mussel damage.
This information was last updated on September 1, 2014
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