Upwelling brings water from the ocean’s depths toward the surface, replenishing surface waters with nutrients. This lesson explains the phenomenon and the physical forces that drive it.
Upwelling is the wind-driven movement of dense, cool, usually nutrient-rich water from depth toward the ocean surface. It replaces warmer surface water, which is often depleted of nutrients. The newly supplied nutrients support phytoplankton, microscopic primary producers that form the base of many marine food webs.
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Ekman spiral
The turning pattern of water motion with depth as friction transfers wind-driven motion through water layers.
Wasp-waist richness pattern
High species diversity at lower and higher trophic levels, with few species at an intermediate level.
Primary production
The amount of carbon fixed by phytoplankton through photosynthesis.
Bathymetry
The depth and shape of the seafloor.
El Niño–Southern Oscillation (ENSO)
A climate pattern that can alter trade winds, upwelling, and marine productivity.
Quiz questions
What wind and water-movement pattern commonly causes coastal upwelling?Answer: Winds blow roughly parallel to shore, and Ekman transport moves surface water offshore.
Why does divergence occur near the equator under easterly trade winds?Answer: The winds drive water westward, and weak Coriolis effects let surface waters move away from the equator.
How does El Niño commonly affect wind-driven upwelling and productivity?Answer: Weaker trade winds reduce upwelling, nutrient delivery, and phytoplankton productivity.
What ecological role do anchovies and sardines often play in upwelling food webs?Answer: They connect plankton to larger predators as abundant intermediate-level prey.
Which local atmospheric conditions are commonly associated with cold upwelled water?Answer: Sea fog and stratus clouds can form, while higher clouds and showers are inhibited.
Based on the Wikipedia article Upwelling, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.