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The Fish Kill Mystery

Erica F. Kosal
Department of Biology
North Carolina State University


In this case study, students speculate on what may have caused a major fish kill in an estuary in North Carolina. In the process, they explore how land runoff and excess nutrients affect aquatic communities, and learn about the complex life cycle of the dinoflagellate Pfiesteria. The case is appropriate for an introductory environmental science course, a general biology course that covers ecology, or a general zoology course.


  • To explain how land runoff may affect aquatic communities.
  • To describe in detail two effects that excess nutrients may have on aquatic ecosystems.
  • To describe the complex life cycle of Pfiesteria as an example of dinoflagellate biology.
  • To describe how human activities have contributed to problems such as eutrophication, which may come back to influence human health.


Fishkill; fish kill; eutrophication; Pfiesteria piscicida; aquatic ecosystems; dinoflagellate; land runoff, excess nutrients; estuaries; estuary; nutrient influx; North Carolina

Educational Level

High school, Undergraduate lower division, Undergraduate upper division



Type Methods




Subject Headings

Environmental Science Ecology Biology (General) Zoology

Date Posted


Teaching Notes

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Supplemental Materials

The following animations are referred to in the case.




Answer Key

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Barbara Biglan
Chatham University
Pittsburgh, PA
I used this case in a cooperative experience with a middle school science teacher and a Chatham colleague. We broke the case into smaller “chunks” that would fit in a 40-minute class period. At the end of each chunk we raised questions for the students to consider, and they wrote responses in a science journal. We created charts to help the students organize information and their answers. We also located and designed activities that corresponded to sections of the case. For example, when the case mentioned dissolved oxygen, we had the students do a hands-on activity to explore the concept of dissolved oxygen. We also used the 5E Model of Inquiry paying particular attention to 2 of the 5 essential features of application and extension. [Editor‘s Note: see for a brief description of this model.] Through the process of exploring the case, students refined their initial hypothesis and cited the evidence for their decisions (again, all of this was recorded in their journals). At the end of the case study, the students had a field trip to an area called Nine Mile Run which empties into the Monongahela River. It was, in the past, a source of contamination and a ”fish kill“ location. It has since been cleaned up and no longer serves as a pollution source.

By taking this case in smaller chunks and exploring vocabulary when necessary, we felt the case was an excellent way to engage middle school students in the process of inquiry.

There is an excellent book, And the Waters Turned to Blood: The Ultimate Biological Threat by K. Baker (Simon and Shuster, 1997), that gives more context to the case and some interesting information about the health effects of this study on the scientists who conducted the research. Another book that might be of interest is one we used by Jean Craighead George, Who Really Killed Cock Robin? An Ecological Mystery published by Harper Collins Children’s Books in 1991.

Patrick Alarcon
Middle School Science
St. Mary School
Ridgefield, Ct 06877
I retired from public high school and I'm teaching in a diocesan middle school. I have used the case studies extensively in high school but I've modified some of them for middle school. As always, I and my students appreciate what your program at Buffalo has done for our understanding of difficult concepts. Science is fun and this could not be more true than when my environmental science class put on a school-wide performance about the content in The Fish Kill Mystery. I have video about segments if you'd like to enjoy them with us. Thank you for allowing me to make the content "real" for my students.