Case Study Your mission is to use your knowledge of networks and life (extreme and non-extreme) to: Analyze how an ecological disturbance could affect an entire ecosystem. Analyze the effect of natural events and human activities on the Earth’s capacity to sustain biological diversity. Institute for Systems Biology & Bellevue School District

Case Study Details Setting: A large body of water Time: 1952 Event: A causeway is built across the body of water separating the north end from the south end. No water is exchanged between the two sides. The general question: What effect does this have on the ecosystem?

The Specifics In 1902, a railroad built a train trestle that went directly across the body of water. In the 1950’s, a causeway replaced the trestle allowing for safer and faster travel of the trains. The causeway is a solid, raised roadway made of 50 million cubic yards of rock, sand and gravel. However, unlike the trestle, the causeway does not allow circulation of water between the two sides. This basically split the lake into two halves, the North arm and the South arm.

The causeway separating the North and South arms

This body of water is a dynamic ecosystem and is affected by the amount of rainfall received 1984 2004

Brainstorming What differences do you notice, if any, between the north and the south arms? Why could building a causeway cause the water to be two different colors? What might be some causes of the change seen?

New Information Only one arm of this body of water receives freshwater on a continuous basis. How could this be? Does this lead to further explanations or does this narrow down your possible explanations? If only one arm is receiving freshwater, what type of ecosystem must this be? Hint: What different types of water ecosystems are found on Earth? Why does the amount of rainfall received further affect this ecosystem?

No Salt Low Salt High Salt

No Salt High Salt Low Salt

The Great Salt Lake Ecosystem

Brainstorming What organisms are part of the ecosystem in the Great Salt Lake? What differences do you notice, if any, between the north and the south arm of the lake? Which half of the lake receives fresh water? How do you think this affects the lake? Why do you think the Great Salt Lake is a different color in the North end of the Lake?

Hypothesizing What factors may affect the growth of Halobacterium? How could you design an experiment that could test your hypotheses?

Optimize The decision strategy of choosing the alternative that gives the best or optimal overall value. To increase the efficiency or effectiveness of a process as much as possible.