After Studying the Experiment of W

Essay

After studying the experiment of W. J. Fletcher described in Figure 52.8 from your textbook, you decide to study feeding relationships among sea otters, sea urchins, and kelp on your own. You know that sea otters prey on sea urchins and that urchins eat kelp. At four coastal sites you measure kelp abundance. Then you spend one day at each site and mark whether otters are present or absent every 5 minutes during daylight hours. Make a graph that shows how otter density depends on kelp abundance, using the data shown below. Then formulate a hypothesis to explain the pattern you observed.
Kelp abundance Otter density
Site (% cover) (# sightings per day)
1 75 100
2 15 20
3 60 80
4 25 33