The Repository @ St. Cloud State

Open Access Knowledge and Scholarship

Date of Award


Culminating Project Type


Degree Name

Biological Sciences - Cell and Molecular: M.S.




College of Science and Engineering

First Advisor

Heiko Schoenfuss

Second Advisor

Timothy Schuh

Third Advisor

Jessica Ward

Fourth Advisor

Nathan Winter

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Keywords and Subject Headings

Pharmaceutical, estrone, fathead, behavior, predator, feeding


With the increased use of pharmaceuticals and endocrine active compounds, more of these chemical compounds are reaching the aquatic environment. Some pharmaceuticals and endocrine active compounds have reported effects concentrations in the nanogram per liter range. However, few experiments have examined the effects of these compounds on larval fish behavior. For the current study, fathead minnows (Pimephales promelas) were exposed to either an ethanol solvent control, diclofenac (1,600 ng L-1), methocarbamol (4,800 ng L-1), rosuvastatin (3,200 ng L-1), sulfamethoxazole (2,200 ng L-1), temazepam (1,600 ng L-1), estrone (E1) at 125 ng L-1 or 625 ng L-1 for twenty-one days in a 50% daily static renewal system. The exposure began three days after fertilization of eggs when eye spots were observed. Following the twenty-one days of exposure, the larvae were subjected to a predator avoidance test to examine whether the pharmaceutical or E1 exposures caused a deficiency in the predator avoidance performance. Larvae exposed to rosuvastatin, diclofenac or 125 ng L-1 E1 exhibited a delayed latency period during the predator avoidance performance (p<0.05). A feeding efficiency test was also conducted to determine the effects of exposure on a larvae’s ability to forage. Only larvae exposed to E1 (125 ng L-1) showed deficiencies in the percentage of brine shrimp consumed. By examining a larvae’s ability to effectively escape predation and to feed efficiently, two main aspects of evolutionary fitness were assessed. Our experiments demonstrated that both pharmaceuticals and E1 can diminish these behaviors. As a consequence, fish may fail to reach maturity, resulting in subsequent loss of reproduction with unknown population level consequences.


Funding for the present study was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources. I thank undergraduate students Wesley Davis and Utko Hasbay at St. Cloud State University for their assistance during behavioral assessment. A special thanks to my graduate committee members, Dr. Timothy Schuh, Dr. Jessica Ward and Dr. Nathan Winter. Most importantly I would like to give thanks to my graduate advisor and mentor, Dr. Heiko Schoenfuss, whose guidance and encouragement helped me push through and overcome the many challenges that I have experienced as a graduate student in the Aquatic Toxicology Lab. Lastly, I would like to thank my family for their continued support throughout my college career.



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