Date of Graduation

Fall 2013


Master of Science in Biology



Committee Chair

M. Chris Barnhart


Unionidae, Dreissena, mussel, suspension feeding, clearance, Zequanox.

Subject Categories



Zebra and quagga mussels, Dreissena, are invasive filter feeders that significantly alter ecosystems. Zequanox; is a particulate biopesticide that kills Dreissena when ingested. The present study investigated factors affecting the filtration and retention of suspended particles, including Zequanox, by five native species of Unionidae and two species of Dreissena. Unionids were tested because of concerns about toxicity of Zequanox to non-target native species. Juvenile unionids were used because of their overlap in size with Dreissena and to examine the effects of size on filtration rate and particle capture. The allometric equation describing mass-specific clearance rate (CR) versus individual dry tissue mass (M) among all species tested was CR = 0.99 M-0.40. Particle retention was affected by particle size but not by body size. Zebra mussel retained sub-micron size particles more efficiently than the other species examined. Zequanox non-target toxicity was tested on four species of native unionids. The concentration of active ingredient lethal to 50% of test animals in 72 hour exposures ranged from 126 mg.L-1 to more than 500 mg.L-1 among the native mussel species tested. Zequanox elevated ammonia and lowered dissolved oxygen, which could contribute to indirect toxicity. Short-term experiments suggested that Zequanox at treatment concentrations could inhibit feeding by zebra mussels. Nearly half of Zequanox particles tested are less than 1 micrometer in diameter, and may not be effectively retained, particularly by quagga mussel and native mussels.


© Madeline Elizabeth Pletta

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