Why is it useful for an ecologist to identify the keystone species in an ecosystem?
a. the keystone species is only important in early stages of succession, and so the ecologist can safely ignore changes in its population at later stages.
b. the keystone species is the most susceptible to pollution, and so its numbers give an indication of the levels of pollutants in an area.
c. the keystone species is critical to maintaining the stability of an ecosystem, and changes in its population indicate changes in ecosystem health.
d. the keystone species is important for the cycling of matter and must be maintained or the biogeochemical cycles will be affected.

The right option is; C. The keystone species is critical to maintaining the stability of an ecosystem, and changes in its population indicate changes in ecosystem health.

Keystone species are the species such as jaguar that has a superfluous impact on its environment relative to its population. The keystone species are important for the general function and structure of an ecosystem and they have an influence on the composition (in terms of plants and animals) of an ecosystem. It is useful for an ecologist to identify the keystone species in an ecosystem because the keystone species is important to maintaining the stability of an ecosystem, and any changes in the keystone species population shows that there is changes in ecosystem health.