Exposure-Related Effects of Zequanox on Lake Sturgeon (Acipenser fulvescens) and lake trout (Salvelinus namaycush) Survival and Condition

Science Center Objects

A dead-cell, spray-dried powder formulation of Pseudomonas fluorescens, strain CL145A was recently approved by the US Environmental Protection Agency (EPA) for control of dreissenid mussels (zebra mussel, Dreissena polymorpha and quagga mussel, Dreissena rostriformis bugensis) in open-water environments.  The EPA approved product, Zequanox® (registration number 84059-15) is manufactured by Marrone Bio Innovations, Inc. (Davis, California) and it was registered for controlling dreissenid mussels in industrial water systems in 2012 and for controlling dreissenid mussels in open-water systems in 2014. Zequanox induces mortality of dreissenid mussels by degradation of the epithelial cells lining the dreissenid digestive system.

Previous research assessing the exposure-related effects of Zequanox to freshwater unionid mussels has suggested that Zequanox exposure to native unionids is safe when it is applied at the maximum approved label concentration and exposure duration of 100 mg/L (active ingredient) for 8 hours (Luoma et al., 2015; Luoma, Weber, Waller, et al. 2015; Weber et al., 2015).  However, laboratory trials conducted using a constant flow system to expose native fish to Zequanox treated water have demonstrated mixed results for native fishes (Luoma et al., in press).

Thorough assessments of exposure-related effects of Zequanox to native fishes are necessary before resource managers should apply Zequanox to control dreissenid mussels in open-water environments. Data needs regarding the use of Zequanox where native trust species such as lake sturgeon and lake trout are present is even greater, given the impacts to lake sturgeon and salmonid species observed in exposures conducted using a constant flow test system (Luoma et al., in press).  


  1. Assess the exposure-related effects of Zequanox on juvenile lake sturgeon (Acipenser fulvescens) and lake trout (Salvelinus namaycush) survival and condition when applied up to the maximum open-water label concentration and exposure duration (i.e. 100 mg/L [AI] for 8 hours).
Zebra Mussels on rock

Zebra Mussels on rock.(Credit: Mike Caucutt, USGS, UMESC. Public domain.)


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Luoma, J.A., Weber, K.L., and Mayer, D.A., 2015 (In press), Exposure-related effects of Pseudomonas fluorescens, strain CL145A, on coldwater, coolwater, and warmwater fish: U.S. Geological Survey Open-File Report 2015–XXXX,  XXXp.

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