SimPredator-Prey: Exploring the Ecology of Invasive Species -  A Case Study-Based Inquiry

Lab Summary


In this case study based lab students are introduced to the Asian swamp eel, an invasive species which has been discovered in freshwater lakes of South Carolina. This hypothetical scenario begins at a public hearing in which several proposals are being put forth by various stakeholders (biologists, politicians, and citizens) to control the spread of this invasive species of fish. The case then leads students to explore the effect of an invasive species on fresh water lake communities through a hands‐on simulation in which students act as predators using feeding tools (knives, forks, spoons and tweezers) to harvest various prey species (different types of beans).  During the simulation students collect and input data into a MS Excel spreadsheet which keeps track of and graphs changes in predator and prey population size, prey capture rates, predator harvest rates and community species diversity. The spreadsheet allows students to quickly and easily observe trends in the data in order to test hypotheses about the ecological effects of invasive species. Additionally, the simulation allows the class to test hypotheses about how the introduction of a bio‐control agent (a nonnative predator simulated with tweezers) may influence the community.

The scenario:


Representative Dawson Cherri fiddled with his pen as he listened to the speaker, Dr. Gerald Saunders, a long-time friend, and a freshwater ecologist at the University of South Carolina.  As a representative on the state legislature, he had sat through his share of lengthy public hearings, but today's discussion was too important to let his mind wander.  He along with other politicians, scientists from the Department of Natural Resources, members of state hunting and fishing organizations and the public had been invited to attend a forum in order to solicit input on controlling the population of Asian swamp eel (Monopterus albus).  This input would be sent to the South Carolina Aquatic Invasive Species Task Force to reach a final recommendation that could be presented to the state legislature.  Dr. Saunders continued, “Asian swamp eel is a species native to Asia from India to China.  Introduction into Florida was believed to be through the aquarium trade or from fish markets, and was later discovered in north Georgia along the Chattahoochee River drainage. It has now appeared in several freshwater ecosystems in western South Carolina.  The Asian swamp eel is a general predator and can grow to 100 cm in length. The greatest concern is its impact on native fishes, and aquatic invertebrates. Interestingly, this species also has the ability to cross land to reach other water bodies from established areas. It can withstand poor water quality and drought and is very difficult to eradicate.  Asian swamp eels have already inflicted massive damage to freshwater systems, and have resulted in the collapse of several sport fisheries in areas where they have been found.  I agree that there does appear to be broad public support for any reasonable measure that might eradicate this species before they become widespread in South Carolina.  However, at this point the safest course of action would be to continue to closely monitor the populations of eels and to continue with the trapping, and fishing efforts already in place.”  Representative Cherri knew that this recommendation would not go over well with many folks attending the meeting, and he was right.  Chatter and even a few “boos” immediately erupted from the audience.  “We have to do something now..”, and “…this fish will absolutely kill my business…”, were just of few of the comments Dawson could make out from the audience chatter.  At that moment, a loud and forceful voice rang out, “I’d like to ask the distinguished professor a question please...”  The room immediately went quiet, as Ned Gibson, a local sport fisherman, was given the opportunity to speak.  “I don’t understand why we should wait on biological control efforts.  After all, it is my view that animals were put on earth for human benefit.  Why don’t you use some of that scientific knowledge to come up with ways we can use predators from their native habitat in China to control these eels?”  Dr. Saunders was not about to let the discussion turn to the release of non-native predators as a bio-control agent.  "Look, although predator introduction has been tried in the past to control other invasive species, the release of non-native predators opens a Pandora's box of new and potentially worse problems.  So I believe we should drop the idea of predator control right now."  Representative Cheri responded, “I too am fully aware of the risks that introduced non-native predator species could pose to the environment but I also know of some cases where species introductions, whether accidental or purposeful, have produced some economic benefits, despite their environmental consequences.  For example the Blue catfish was introduced into lake systems in South Carolina during the 1960s. These fish now thrive and have become widespread in lakes, especially in the Santee Cooper system, and blue catfish now support a large recreational and commercial fishery”.  The room fell silent as Dawson pondered the options before the committee.  There were still two weeks before the panel would convene to discuss the recommendations.  He wondered if any consensus was possible.

Conceptual Learning Objectives

  • To explore the effects that introduced species can have on the ecology of a community (prey & prey population sizes, prey feeding rates, community biodiversity).
  • To use an ecological simulation to test hypotheses about the effects that the introduction of a bio-control agent on the above population and community level parameters.
  • To better understand the complexities involved in managing our natural resources given the interests of various stakeholders, and how scientific knowledge can be used to inform management decisions.


Learning Theory & Pedagogy

Case Studies or Problem Based Learning initially catalyze learning with a story, problem, query or issue that is engaging to the learner.  Problems and case studies are complex, engaging and relevant to the learner, often controversial in nature, and require the application of scientific concepts to fully understand them and reveal workable solutions.  This case-based lab reverses the traditional relationship between content and application in lab by using a compelling scenario to catalyze and drive students’ efforts to construct content understanding.


Instructional Resources
  • An instructor guide which provide lab instructors with lab preparation instructions, suggested materials, learning theory and pedagogical suggestions.
  • A MS Excel spreadsheet which which keeps track of and graphs changes in predator and prey population size, prey capture rates, predator harvest rates and community species diversity.  This allows students to use trends in data to evaluate their hypotheses, an minimizes time students must spend doing repetitive calculations.

Required Materials
  • 1 or2 (depending on class size) 4 x 8 rugs with heterogeneous colors or texture
  • Teaching computer with projector.
  • Student team lab computers
  • Plastic forks, knives, spoons and tweezers
  • Various prey items (beans, string, toothpicks etc..)
  • This lab works best with class sizes between 20-30 students.