Nonoxidizing chemicals and molluscicides are used generally after a zebra mussel problem has developed. Four proprietary products are discussed in EPRI (1993) under the general category of quaternary ammonium compounds or polyquats: Clamtrol CT-1, Calgon H-130, Bulab 6002, and Mactrol 7326. These are proprietary and are very effective against zebra mussels, but due to their broad spectrum toxicity, they have to be detoxified prior to their release. It is generally believed that this may be accomplished with the use of bentonite clay, but no studies have yet been published to confirm this. Claudi and Mackie (1994) indicated that these quaternary ammonium compounds are acutely toxic to fish and other aquatic life, and that the fate of these complex products in sediment is not well-documented.
Nonoxidizing compounds are quite toxic to the zebra mussel at concentrations of greater than 0.5 ppm, but are also toxic to nontarget organisms at similar and lower concentrations. These compounds readily and strongly adsorb to sediments, clay particles, organic matter, and other negatively charged surfaces. Following adsorption they are degraded by microbes and therefore water column concentrations are normally very low (EPRI 1993).
The Bulab 6002 product does not readily degrade in water, but is highly adsorptive to sediments and to glassware (EPRI 1993). Concentrations toxic to the zebra mussel are in the range of 4 to 8 ppm with lower concentrations if expressed as an active product. These concentrations are greater than those reported toxic to nontarget organisms (EPRI 1993).
Potassium salts are very toxic to the zebra mussel. At concentrations up to
100 ppm adult zebra mussels are killed. The toxicity of potassium chloride (as well as several other chemicals) to nontargets were discussed in Waller and Fisher (1998) where toxicity to several nontarget species was confirmed.
Management and Control Contents