EVALUATION OF SEVERAL CHEMICAL DISINFECTANTS FOR REMOVING ZEBRA MUSSELS FROM UNIONID MUSSELS

We evaluated the safety and effectiveness of chemical treatments for k illing veliger and juvenile stages of the zebra mussel Dreissena polym orpha attached to unionid mussels. Static toxicity tests were conducte d on eight unionid mussel species with common aquaculture chemicals (b enzalkonium chloride, formalin, hydrogen peroxide, calcium chloride, p otassium chloride, and sodium chloride). The concentration and duratio n of each chemical treatment tested had previously been found to kill zebra mussel veligers and juveniles. Several species (e.g., Elliptio d ilatata, Lampsilis cardium, and Lasmigona complanata) incurred less th an 10% mortality in chloride salt treatments, while in other species ( e.g., Obliquaria reflexa and Leptodea fragilis) mortality varied great ly among treatment regimes. Treatments with benzalkonium chloride, for malin, and hydrogen peroxide were less than 90% effective on juvenile stages of zebra mussels and, therefore, were ruled out after prelimina ry trials. Limited application of specific chemical treatments may be feasible for more tolerant species; however, effective disinfection of unionid shells will require the use of chemical treatment followed by a quarantine period to completely remove zebra mussel larvae and juve niles.