A Large Lake in a Relatively Isolated Environment Has Had

A large lake in a relatively isolated environment has had clear water and a stable,moderately diverse species composition for hundreds of years.When the region is developed into farmland,the lake begins receiving large amounts of fertilizer runoff,making it turbid and highly eutrophic (excessively rich in nutrients) .The species composition becomes much less diverse and is made up of species that tolerate low oxygen.Even after the farmland is abandoned and fertilization stops,the lake remains eutrophic.This is an example of a(n)

A) disturbance.
B) ecological transition.
C) successional change.
D) environmental gradient.
E) change in habitat structure.