The cold ocean waters off the coast of Peru, a country in South America, are some of the most nutrient-rich waters in the world. An ocean current named the Humboldt Current
helps bring cold water up the western coast of South America from the Antarctic. This
cold water can hold more oxygen than warm water can. As wind patterns push surface
water away from the shore, deep water full of nutrients rises to the surface. This is
called upwelling. The diagram shows how upwelling occurs.
Underwater View
of Upwelling
Offshore
surface water
movement
Warm
nutrient-poor
surface water
Continental
Cold
shelf
nutrient-rich
water
Cold Continental
bottom slope
water
A small fish called the anchovy can be found in the cold ocean waters off the coast of
Peru. The anchovy population in Peru is one of the most important fish populations in the
world.
The anchovy is critical to the health of the ocean ecosystem off the coast of Peru.
Changes to the anchovy population have a major impact on other organisms in the
ecosystem. A food web for that ecosystem is shown. This food web shows the
relationships among organisms, including anchovies, in the ecosystem. It also shows the
movement of energy through the ecosystem. A basic energy pyramid is shown as well.
Which factor makes the ocean off the coast of Peru one of the best
ecosystems for sustaining the largest fish populations in the world?
A. the cold waters traveling up the coast of South America with large amounts of
nutrients needed in the ecosystem
B. the cold winds from the equator bringing nutrients from the western oceans
needed in the ecosystem
C. the warm waters from the westem oceans that bring large amounts of
nutrients needed in the ecosystem
D. the warm winds that move the nutrients needed in the ecosystem to the
coastal areas