Which of the Following Might Be Best Explained by a Trophic

Question

Which of the following might be best explained by a trophic cascade?
A) Numbers of a snail eating fish go up and the numbers of snails go down.
B) Numbers of lions go down and the numbers of zebras go up.
C) Numbers of grazing catfish go down and numbers of algae go up.
D) Numbers of a stream predatory fish go up and numbers of algae go down.

Accepted Answer

A trophic cascade is a phenomenon in which a change in the abundance of a top predator has a cascading effect on the abundance of lower trophic levels. In this case, the predatory fish is at the top of the food chain, and its increase in numbers would lead to a decrease in the numbers of algae, which are at the bottom of the food chain.