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Dead Fish in Bear Pond

Paleoecology and Clues at the Core


Krista E. Slemmons
Department of Biology
University of Wisconsin-Stevens Point


This interrupted case study introduces students to the complexity of understanding natural variation in ecosystems through time in the absence of long term data sets. In particular, students explore the interdisciplinary nature of ecology and examine how paleoecology can enhance our understanding of how aquatic ecosystems behaved in the past. The case tells the story of a college biology major who revisits a family lakeside cabin in Maine only to find the shoreline covered in dead fish and rotting trees. As students read the story, they are asked to develop hypotheses as to the possible cause of this ecosystem disruption using data presented in the form of deposition maps, graphs, and observations. Students are introduced to the basic ecology of diatoms and examine how they can be used to reconstruct past environmental conditions. The case was designed for an introductory level biology class, environmental science class, or majors ecology course. The case could be adapted for either a majors or non-majors course depending on the use of the extensions described in the teaching notes.

  • Simulate the scientific process of making observations, examining data sets, formulating and evaluating hypotheses, and designing experiments.
  • Define the terms acid, acid rain and pathways of acid rain.
  • Describe the ecological ramifications of acid rain on aquatic systems.
  • Explain the complexity in solving environmental issues.
  • Evaluate the use of paleoecology in providing long-term data sets.
Keywords: Testable hypotheses; experimental design; acid rain; ecological interactions; methods in aquatic ecology; paleoecology; biogeochemical cycles; basic chemistry; algal ecology
Topical Area: N/A, Scientific method, Regulatory issues
Educational Level: High school, Undergraduate lower division, Undergraduate upper division
Formats: PDF, PowerPoint, Excel
Type/Method: Analysis (Issues), Discussion, Interrupted
Language: English
Subject Headings: Atmospheric Science   Biology (General)   Botany / Plant Science   Ecology   Environmental Science   Limnology   Natural Resource Management   Science (General)  
Date Posted: 3/21/2019
Date Modified: N/A
Copyright: Copyright held by the National Center for Case Study Teaching in Science, University at Buffalo, State University of New York. Please see our usage guidelines, which outline our policy concerning permissible reproduction of this work.

Teaching Notes

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Answer Key

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Supplemental Materials

The files below are designed for instructor use and restricted to subscribers.

  bear_pond.pptx (~4.6 MB)
This optional PowerPoint presentation provides visual context for the location of the scenario and serves to enhance the narrative and structure class discussion.
  bear_pond.xlsx (~18 KB)
This Excel worksheet is for an optional extension to the case and contains simulated diatom counts so that students can calculate the inferred diatom pH for Bear Pond and create a graph of time.

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