The sea otter (Enhydra lutris) is a marine mammal native to the Pacific Coast of North America. Sea otters were once hunted heavily for their fur, and their global population went from hundreds of thousands in the late 1700s to only 1,000 to 2,000 by the beginning of the 1900s. Sea otters are now protected, but habitat loss and pollution have kept their numbers from recovering completely, and they are still listed as endangered.
Sea otters are considered a keystone species because one of their primary sources of food is the purple sea urchin. Sea urchins are herbivorous echinoderms that feed on brown kelp. Forests of brown kelp support a very high diversity and richness of species.
Based on the interactions just discussed, which of the following statements describes a habitat that sea otters have been removed from?
A. The population of purple sea urchins is high, and they have been feeding heavily on the kelp. With the removal of the kelp forest, the species richness has increased.
B. The population of purple sea urchins is high, and they have been feeding heavily on the kelp. The kelp forest is thin or nonexistent, and the species richness of the habitat is very low.
C. The population of purple sea urchins is low, which has led to an increase in the population of kelp. The kelp forest is dense and supports a high species richness.