The Non-linearity of Environmental Change: A coral reef model
This activity was selected for the On the Cutting Edge Exemplary Teaching Collection
Resources in this top level collection a) must have scored Exemplary or Very Good in all five review categories, and must also rate as “Exemplary” in at least three of the five categories. The five categories included in the peer review process are
- Scientific Accuracy
- Alignment of Learning Goals, Activities, and Assessments
- Pedagogic Effectiveness
- Robustness (usability and dependability of all components)
- Completeness of the ActivitySheet web page
For more information about the peer review process itself, please see http://serc.carleton.edu/NAGTWorkshops/review.html.
This page first made public: May 16, 2012
The course uses this popular environment as a proxy for environmental decline in general and has two broad goals beyond the course content:
1) to encourage science majors to think about complex environmental problems outside the context of their individual major, and
2) to help non-majors understand the scientific thought process in the context of their own personal interests and opinions.
The computer model described here was built to provide a user-friendly interface that is visually stimulating but non-"threatening" to math-phobic students. It runs on FREE software that can be run on any computer. It can be run and modified by an instructor or student with no modeling skills.
For this exercise, it demonstrates how losses of grazing fish and/or the addition of nutrients to the reef system will reduce the relative abundance of corals and algae on the reef - leading to eventual decline. The main lessons for the students are:
1) If you increase a particular stress, there is often little or no change until suddenly the system rapidly declines.
2) If multiple stresses are added, the pattern is more complicated but basically the same.
3) Once the system collapses, simply returning to the "safe" side of the collapse threshold has no result.
The Big Picture: All of this is referred to as "non-linearity" and demonstrates that on the reef (as in most natural systems), it's a LOT easier (and cheaper) to not "break it" in the first place than it is to "fit it" once it crashes.
1) a Powerpoint describing the balance between corals, grazing fish, nutrients and algae on a "healthy" reef.
2) a detailed set of instructions for running the model that can be used by both the instructor and the students
3) a detailed set of scenarios and questions (including answers - remember to remove them before giving them to your students) that helps the teacher understand what the model is showing. Once you go through the provided exercise, you should be ready to decide whether to run it as is or to modifiy it for your needs. To do the latter, you need no programming skills.
Skills and concepts that students must have mastered
How the activity is situated in the course
1) a short background lecture (Powerpoint provided)
2) instructions and hands-on demo of the model
3) homework assignment or lab exercise to use the model
4) discussion of model outcomes
Content/concepts goals for this activity
Higher order thinking skills goals for this activity
Other skills goals for this activity
Description and Teaching Materials
- The NetLogo model can be downloaded for free and works on any computer. It can be downloaded from: NetLogo. If the link is broken, simply Google "NetLogo" and go to their download page.
- The CoralReefs model can be downloaded from: Coral Reef Exercise by Denny Hubbard
Teaching Notes and Tips
We created a detailed assessment that examined both what and where students learned in this exercise. While the model reinforced the basic principles, much of that information was effectively transmitted in the lecture. However, the depth of thinking about the natural system and the appreciation of a) the non-linearity, and b) the process of scientific thinking are learned came primarily from the hands-on exercise and the following discussion. A copy of this survey can be requested through the Geology Department at Oberlin College.
References and Resources
Introduction to Ocean Sciences by Douglas Segar