Acute toxicity tests and pulsed-dose delayed mortality at 12 and 22�C in the zebra mussel (Dreissena polymorpha)

Abstract

Three potential chemical controls (sodium hypochlorite, hydrogen peroxide, and poly[oxyethylene (dimethylimino) ethylene (dimethylimino) ethylene dichloride] (commercial trade name BULAB 6002)) were evaluated for acute toxicity to small adult zebra mussels (Dreissena polymorpha) in chronic and pulsed-dose laboratory trials at two temperatures. All three control agents tested effected greater mortality ofD. polymorpha at 22°C than at 12°C. In most cases the mortality level at 12°C was one half or less that incurred at the higher temperature. Analysis of variance showed significant effects of temperature in the case of BULAB 6002 and for hydrogen peroxide; plots of cumulative mortality through time show this trend as well. The relationship between mussel valve length and time-of-death is consistently positive but is significant in few individual treatments, however, when treatments (all concentrations and temperatures) for a single biocide are pooled, the relationship is significant and explains 16–26% of the variance. This suggests that control programs might be more effective if they are initiated whenD. polymorpha are small. Pulsed-dose control programs also are affected by temperature but generally are likely to be more cost-effective than continuous application control programs and would result in lower overall discharge of biocides to surface waters. Hydrogen peroxide at concentrations of 12.0, 20.0, or 30.0 mg/L is a quick acting control agent that probably will have fewer long-term consequences for nontarget organisms in discharge areas or for municipal water users than either BULAB 6002 or, especially, sodium hypochlorite.