The Repository @ St. Cloud State

Open Access Knowledge and Scholarship

Date of Award


Culminating Project Type


Degree Name

Biological Sciences - Ecology and Natural Resources: M.S.




College of Science and Engineering

First Advisor

David Kramer

Second Advisor

Alfred Hopwood

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Share Alike 4.0 License.

Keywords and Subject Headings

Farm, Chemical, Herbicide, Rana Pipiens larva, Biology


Groups of 20 Rana pipiens larvae were exposed to Atrazine, Chloramben, or Alachlor in a 96-hour, static bioassay. Threshold lethal concentrations of 8.5 ppm and 250 ppm were determined for Atrazine and Chloramben, respectively, for larvae at Taylor-Kollros Stage I. The threshold lethal concentration of Alachlor was 1.5 ppm for larvae at Taylor-Kollros Stage III.

Determinations of growth inhibition, group variability, and examinations for external abnormalities were made 40 days after the termination of the 96-hour exposures at the lethal thresholds of Atrazine and Chloramben.

Atrazine and Chloramben did not significantly inhibit growth under those conditions, but did induce a greater degree of variability in weights, lengths, and developmental stages of the larvae. The larvae exposed to Chloramben showed no physical abnormalities. Thirty-two percent of the Atrazine exposure group showed a skin abnormality resembling warts.


I wish to thank the Amchem Company, the Monsanto Chemical Company, Binsfeld Nursery, and Mimbach's Fleet Supply for their donations of herbicides.

I also wish to thank Dr. D. C. Kramer, and Dr. A. J. Hopwood, of St. Cloud State University, Dr. G. c. Veith of the National Water Quality Laboratory, and Mr. -K. s. Miller for their critical evaluations of this paper and their continued support.

Mr. A. E. Lemke and Mr. J. H. McCormick, of the National Water Quality Laboratory, assisted with the statistical analysis of the data, and aided with the figures, and deserve thanks for their help.

Above all I wish to thank my wife, Julie, for her patience throughout the study and for her assistance in the writing and typing of this paper.

Included in

Biology Commons



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