Trophic Cascades

Instructions

Go to the following web link- http://media.hhmi.org/biointeractive/click/trophiccascades/?_ga=2.71133017.874546303.1495559246-1279517233.1480957413

Complete the first slides of the introduction. Next, follow the first example of sea otters, and answer the following questions. Then evaluate one of the case studies. This assignment is worth 15 points.

1. What does the otter eat? _________________ (1 point)

2. What happened to the kelp forest when the otter was hunted to near extinction?  (1 point)

3. Is the otter diet a direct or indirect effect on kelp? Explain.  _________________ (2 points)

4. Is the otter diet a positive or negative effect on kelp? Explain. _________________  (2 points)

5. Removal of the sea otter, a top predator also had an impact on two other species, the gull and the Eagle. How did the gull diet change with the removal of the otter from the ecosystem?  How did the eagle diet change with the removal of the otter from the ecosystem? (1 points)

6. Choose 1 of the case studies provided and analyze what happens when the top predator is present, including all direct, indirect, positive and negative effects at each and every trophic level.  It may be useful to sketch it out with dotted/solid lines and +/- symbols. Then, do the same analysis of what happens when the top predator is removed. For example, a polar bear eats seals. So, you would say the polar bear has a direct negative effect on the seals. And so on. (8 points)