After examining Figure 52.19, you decide to study feeding relationships among sea otters, sea urchins, and kelp. 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 the day. Graph kelp abundance (on the y-axis) versus otter density (on the x-axis), using the data below. Then formulate a hypothesis to explain any pattern you observe.

Seaweed is an example of a primary producer because seaweed can produce their food with the help of sunlight.Kelp is also used as the food source for many organisms, and those organisms, in turn, are sources of food to others.

Kelp has a root-like structure that is beneficial for them when they attach to rock. Generally, kelp forests grow on rocky reefs or sometimes on small rocks scattered in different places.

Sea otters are marine animals and are considered under the list of mammals.The hairs or furs on the sea otters’ bodies are denser than other animals present on Earth (approximately more than 1 million hairs in one square inch).

Southern sea otters are on the list of endangered species according to the Endangered Species Act. The primary reasons are decreasing population range and size, the risk for oil spills from coastal tankers, and their vulnerability against oil spills.

From the graph presented above, kelp abundance is greater when the density of sea otters is also higher. In low otter density (in X-axis), the kelp abundance (in Y-axis) is also lower.

In the graph, for site 1, the otter density is 98, the value of kelp abundance is 75, and this site has the most amount of otter density and kelp abundance. Sea otters will use sea urchins as their food source, and sea urchins will eat kelp.

This indicates that the higher number of sea otters will consume more sea urchins, which will decrease their number. A low number of sea urchins will consume less sea kelp, and hence, their number will be higher.