Which phenomenon causes nutrient depletion in surface waters along the coast of South America during El Niño events?

💡 Explanation

During El Niño, weakened trade winds diminish upwelling because the thermocline deepens, reducing the availability of nutrient-rich colder water at the surface. Therefore suppressed upwelling occurs, rather than algal blooms, increased runoff, or reduced solar absorption, all of which require different oceanic conditions.

• Which risk increases when earthquake shaking exceeds the seismic design spectrum of a concrete dam?
• Which outcome occurs when wave action undermines a coastal arch, forming offshore stacks?
• Which risk increases when prolonged heavy rainfall saturates materials of completed coastal levees?
• Which risk significantly increases when island vegetation dies?
• Which outcome occurs when a barrier island migrates landward?
• In periglacial regions with significant solifluction, creating elevated roads requires which additional mitigation measure to maintain stability?