EFFICACY OF CANDIDATE CHEMICALS FOR PREVENTING ATTACHMENT OF ZEBRA MUSSELS (DREISSENA-POLYMORPHA)

Forty-seven chemicals having potential for preventing the attachment o f zebra mussels Dreissena polymorpha were identified and tested. For e ach chemical, 15 zebra mussels (5-8-mm shell length) in each of two re plicates and six treatments were exposed for 48 h followed by a 48-h p ostexposure period in untreated water. Eleven of the chemicals inhibit ed the reattachment of zebra mussels after the 48-h exposure. eight ha d EC50 values ranging from 0.4 to 5.4 mg/L, and three had EC50 values ranging from 19.4 to 29.0 mg/L. Based on an analysis of chemical cost, solubility in water, anticipated treatment concentrations, and potent ial hazards to humans or the environment, three of the most promising chemicals, all antioxidants, (butylated hydroxyanisole [BHA], tert-but ylhydroquinone, and tannic acid) were tested on nontarget fish (bluegi ll, Lepomis macrochirus; channel catfish, Ictalurus punctatus; and rai nbow trout, Oncorhynchus mykiss). These chemicals were not selectively toxic to zebra mussels: only the tests with bluegill and BHA and with channel catfish and tannic acid had 48-h LC50 values greater than the concentrations effective for preventing the reattachment of zebra mus sels. Although the attachment of zebra mussels can be prevented with s elected antioxidants, an alternative formulation should be investigate d to minimize effects on nontarget organisms, such as fish.