Question

Beaked whales feed at various depths, but they defecate at the ocean's surface. Nitrogen-rich whale feces deposited in surface waters supply nutrients for algae that are eaten by surface-dwelling fish. Which of the following best predicts what would happen if the whale population decreased?

(A) There would be a reduction in surface nitrogen concentration, which would cause an algal bloom.
(B) The surface fish populations would decline due to reduced populations of algae.
(C) The remaining whales would accumulate mutations at a faster rate.
(D) The remaining whales would be forced to forage in the deepest parts of the ocean.

Answer 1

(B) The surface

According to the passage, nitrogen-rich whale faeces in surface seas provide nutrients for algae, which are devoured by surface-dwelling fish. If the whale population declined, less whale faeces would be deposited in surface waters, reducing the nutrients accessible to algae. This would lead to a decrease in the number of surface-dwelling fish that feed on these algae.