Date of Award


Document Type


Degree Name

Master of Science (MS)



First Advisor

David Janetski, Ph.D.

Second Advisor

Daniel Widzowski, Ph.D.

Third Advisor

Thomas Simmons, Ph.D.


Pharmaceuticals are concerning forms of water pollution. Understanding of how these contaminants impact biological communities is only beginning to emerge. Some freshwater invertebrates exhibit behavioral changes, such as greater aggression. I examined aggression by crayfish in response to O-Desmethylvenlafaxine (ODV). My goal was to quantify aggression between individuals exposed to varying ODV concentrations. My project comprised: a captive experiment in a laboratory, and a wild experiment designed to assess aggression of crayfish from streams. For the captive experiment, I analyzed video footage to determine numbers of attacks per minute by crayfish (concentrations: 0, 1, or 8 μg/L). Versus controls, crayfish at 8 μg/L ODV more consistently attacked their opponents. For the wild experiment, crayfish from above and below water treatment discharges were similarly analyzed. No relationship was detected between aggression and wild ODV concentration. Results showing increasingly consistent aggression may imply higher energy demands in streams with higher ODV concentrations.