CASE TEACHING NOTES for "Improving on Nature?" by Dennis Kingery Biology Department Metropolitan Community College Omaha, Nebraska

INTRODUCTION / BACKGROUND

History is filled with cases in which humans have sought to change their natural surroundings with unforeseen and harmful effects.  Often the impetus for change is an economic benefit thought conveniently possible with only minor tinkering of the local ecosystem.  Typically, in such cases, knowledge of the ecosystem is lacking, and the consequences of the "tinkering" are only understood in retrospect, too late to avert a disaster.

In 1958 a new fish, black bass, was introduced into Lake Atitlan in the highlands of western Guatemala.  Making this highly prized fish available was seen as a way to attract tourism and boost the local economy.  This was done at the suggestion of Pan American World Airways and with the approval of the local tourism-promotion board.  The area around Lake Atitlan, a national park since 1955, was mostly unknown to the rest of the world, and Guatemala was eager to become a prime destination for tourists.

Introducing an alien species is risky enough by itself, but various unforeseen complications resulted in an ecological disaster.  The introduction of the bass reduced the lake's other populations and was the beginning of the extinction of a rare bird, the giant grebe.  In the end, the introduction of the bass population was not an economic boon.  But in the 1950s, when the events narrated in the case occurred, the process of conducting an environmental impact study to predict possible outcomes was not part of anyone's thinking.

This case first casts students in the role of the local population at that time and asks them to judge the proposal.  Later, they review the ensuing events from a historical perspective.  The case is suitable for introductory biology courses, best used after the students are knowledgeable about ecology, genetics, and evolution.

Objectives:

Upon completion of this case study, students should be able to:

• explain the risks of the introduction of alien species into an ecosystem;
• identify the roles of human activity in the extinction of the giant grebe; and
• describe the effects of environmental change on the Lake Atitlan ecosystem.

CLASSROOM MANAGEMENT

Typically people involved in a discussion see only the parts that they want to see, or are informed only on limited aspects of the issue.  To provide this sort of context for the case study, the students are divided into three groups to discuss the proposal, each from its own perspective:  (1) those familiar with black bass fishing, (2) those familiar with the local villages, and (3) those familiar with the lake ecosystem.  Information useful to each group is provided in separate summaries ("Background Briefings"), one for each group, representing the information available at the time of the bass introduction proposal.  The dialogue between Carlos and Iliana can be provided on one side of a handout page and a Background Briefing on the other.

Each group has four tasks:

• become familiar with the information provided;
• discuss the proposal that black bass be introduced into Lake Atitlan to promote tourism and thus aid the economy of the area;
• decide whether to support or reject the proposal; and
• prepare to defend its position in a public forum.

The instructor plays two roles.  First, he/she moderates the discussion of the fish introduction proposal among the Guatemalan villagers with "1950s thinking," leading to the acceptance of the plan.  Then, he/she facilitates an understanding of historic events as they happened, leading the discussion with some "21^st century thinking."

Timing depends on the length of class sessions available.  With 50-minute sessions, two days will be required to complete the case.  The village meeting can be held during one class session, up to the point at which the bass proposal is accepted.  During the next class session, the groups reorganize to analyze the historic events.

Phase I:  The Community Discussion of the Proposal

1. Allow the groups time to familiarize themselves with the information provided in the Background Briefings and to discuss the pros and cons of the proposal from their assigned viewpoint.
2. Convening a public hearing on the proposal, ask for the opinion of each group, role-playing the part of a moderator seeking consensus on a major project.  You may want to play the role of the representative of the Tourism Commission from Guatemala City.  Keep in mind that the setting is 1958.  Back then we didn't know as much as we know now, so you may have to watch for insights representing more recent thinking.  (If the student-villagers are all opposed to the plan, your case goes nowhere!)  It may be that some groups will question the introduction of an exotic species in principle, i.e., we have made many mistakes like this before and should be wary.  If this happens, agree in principle, but ask for specific objections based on the information at hand.  Accept any idea as a possibility, but lean toward trying the plan.
3. If there is no compelling reason to stop the project, and the consensus seems to be that the people of Guatemala could ultimately benefit, announce that the president of Guatemala has given his approval and that 2,000 young black bass will be introduced into Lake Atitlan tomorrow.  "Fishermen, make your plans and pack your bags for some exciting fishing in Guatemala!  Amigos, prepare for a new wave of visitors to Lake Atitlan!"

Phase II:  The Historic Narrative—What Really Happened at Lake Atitlan

Since this was a real event, the focus changes to a review of history.  The groups reorganize to discuss and analyze the historic episodes as they are revealed.

The student groups should be "shuffled" so that each contains about equal representation of the original factions:  bass promoters, ecology experts, and those familiar with the villages around Lake Atitlan.  This reorganization can be done conveniently by marking a code number or letter in advance on each of the Background Briefing sheets.  The reorganized "jigsaw" groups then represent a broader knowledge base than the first ones, and the members pool their expertise to better understand the predicaments that history recorded.  In a large class section, more than three groups may be needed.  The instructor will have to decide on the appropriate size of the groups, but six (two from each original group) is a good maximum for getting the involvement of all in the discussion.

The historic narrative reveals new information little by little, in much the way we tend to find out things too late and then must try to make adjustments based on the new information.  The new information is divided into segments called "Historic Updates," each presented on a separate page with discussion questions.  Typical responses to the questions posed in each of the Historic Updates are given in the answer key to this case.

Historic Update I Historic Update II Historic Update III Historic Update IV Historic Update V Historic Update VI Historic Update VII

ANSWER KEY

Answers to the questions posed in the case study are provided in a separate answer key to the case.  Those answers are password-protected.  To access the answers for this case, go to the key.  You will be prompted for a username and password.  If you have not yet registered with us, you can see whether you are eligible for an account by reviewing our password policy and then apply online.

REFERENCES

Note:  Considerable background information was gained by the author in a visit to Lake Atitlan which is not necessarily represented in these references.

Print Sources

• Davis, J.T., and J.T. Lock, 1997.  Largemouth Bass: Biology and Life History.  Southern Regional Aquaculture Center Publication 200.
• Geyer, G., 1973.  The Bass is a Gringo in Guatemala. International Wildlife.  Sept./Oct., pp. 18-19.
• LaBastille, A., 1990.  Mama Poc: An Ecologist's Account of the Extinction of a Species.  New York: W. W. Norton.
• LaBastille, A., 1990.  And Now They are Gone. International Wildlife.  July/Aug., pp. 18-23.
• LaBastille, A., 1994.  Birds of the Maya. Geographical Magazine.  Nov., pp. 19-22.
• Tidwell, J. H., S.D. Coyle, and T.A. Woods, 2000.  Species Profile: Largemouth Bass.  Southern Regional Aquaculture Center Publication 722.

Internet Sources

• Maas, P.  "Atitlán Grebe," Peter's Homepage—Recently Extinct Animals.
  http://home.conceptsfa.nl/~pmaas/podilymbus-gigas.htm
  Last updated 25 January 2002.
• Texas Parks and Wildlife.  "Largemouth Bass," Texas Freshwater Fishing.
  http://www.tpwd.state.tx.us/fish/infish/species/lmb/lmb.htm

Photographic Sources

• Association of Guatemalan Tourism Guides.
  http://www.agtg.org

Acknowledgements:  This case study was developed with support from The Pew Charitable Trusts as part of the Case Studies in Science Workshop held at the University at Buffalo, State University of New York, on June 10-14, 2002.

Image Credit:  Photograph of Lake Atitlan, Guatemala, provided by the Association of Guatemala Tourism Guides, a member of the World Federation of Tourist Guide Associations.  Used with permission.
Date Posted:  05/14/03 nas

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