Final answer:
Upwelling along the coast of Ecuador and Peru is especially strong during El Niño events, when warm water replaces the usually cold, nutrient-rich currents, disrupting the marine ecosystem and causing extreme weather.
Step-by-step explanation:
Exceptionally vigorous upwelling along the coast of Ecuador and Peru occurs during El Niño events. Upwelling is a process where deep ocean waters rise to the surface when prevailing winds blow along surface waters near a coastline, bringing up nutrients from the ocean depths.
During normal years, the Andean coast near the Equator experiences cold currents from the Antarctic, which are nutrient-rich and support abundant sea life.
However, during an El Niño event, these cold waters are replaced by warmer currents, leading to a disruption in the marine ecosystem and often causing extreme weather conditions, like heavy rainfall and flooding in coastal regions. The changes in sea temperature and weather patterns due to El Niño can affect deserts, mountains, and farms, as well as causing large die-offs of fish and marine mammals.