Questions and Answers
What is upwelling?
What causes coastal upwelling?
Wind drives surface current in the same direction.
There are ___ major regions of coastal upwelling.
5
What are biological consequences of coastal upwelling?
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How does upwelling stimulate production?
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What causes equatorial upwelling?
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What is the productivity in the Southern Ocean during winter?
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What is the result of the Antarctic divergence?
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Most significant upwelling events are caused by tidal effects.
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What does the displaced water in coastal upwelling get replaced by?
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What is a problem associated with coastal upwelling?
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Study Notes
Upwelling Overview
- Upwelling refers to the upward movement of water, generally driven by wind-induced stress at the sea surface.
- It enhances primary production by bringing nutrient-rich water to the surface.
Coastal Upwelling
- There are five major coastal upwelling regions, with four located on western coasts.
- Numerous smaller upwelling areas also exist along various coastlines.
Causes of Coastal Upwelling
- Wind causes surface currents to move in the same direction; in the Northern Hemisphere, currents turn right, while in the Southern Hemisphere, they turn left due to the Coriolis Force.
- Offshore movement of surface waters is replaced by cold, nutrient-rich water from below.
Biological Consequences of Coastal Upwelling
- Coastal upwelling leads to very high marine production.
- Example outputs include 26 million tons of sardines from West Africa and over 12 million tons of anchovies off Peru.
- Coastal upwelling regions contribute to more than half of the world’s fish catch.
Mechanism of Production Stimulation
- Upwelling introduces essential nutrients like nitrate and ammonia, but mixing can carry phytoplankton out of the productive euphotic zone.
- Calm periods after upwelling and stratification support enhanced primary production; with the Peruvian System being a notable exception.
Case Study: Canary Current System
- Strong winds create a significant equatorward current, surpassing 30 cm/s.
- Features a two-layer circulation system, with cold nutrient-rich water upwelling near the shore and flowing offshore.
Pulses of Upwelled Water
- Cold upwelling periods result in low production, while warm, stratified phases lead to high production levels.
Equatorial Upwelling
- The South Equatorial Current flows westward between 5°S and 5°N, influenced by the Coriolis Force which causes divergence at the equator.
- Upwelling at the equator replaces displaced water, promoting high biological productivity.
Biological Consequences of Equatorial Upwelling
- High primary production near the equator leads to mature communities; productivity typically peaks as distance from the equator increases.
Productivity in Southern Ocean
- Winter ice limits light, resulting in low production, while summer sees no light constraint and substantial peaks in biological activity.
- Southern Ocean is approximately 100 times more productive than Arctic waters.
Antarctic Divergence
- Consists of two significant wind-driven currents: East Wind Drift (anti-clockwise) and West Wind Drift (clockwise).
- The Coriolis Force causes these currents to diverge, leading to upwelling of nutrient-rich waters.
Summary of Upwelling
- Large-scale upwelling occurs due to wind-driven currents and the Coriolis Force, which replaces displaced water with nutrient-rich deep water.
- Major upwelling regions include coastal areas, the equator, and the Southern Ocean, all known for high primary production levels.
Factors Influencing Upwelling
- Significant upwelling events are primarily driven by wind-induced stress at the sea surface.
- Upwelling enhances primary production by supplying nutrient-loaded water to the surface.
Coastal Upwelling Regions
- There are five primary areas of coastal upwelling, with a multitude of smaller regions also present.
Current Directions
- In the Northern Hemisphere, surface currents turn right, whereas they turn left in the Southern Hemisphere.
Current Behavior
- Current flow moves offshore after traveling at right angles to the coastline, displacing surface water.
Replacement Water in Coastal Upwelling
- Displaced water is substituted by cold, nutrient-rich water along the coast.
Challenges of Coastal Upwelling
- Although upwelling provides key nutrients, mixing can lead phytoplankton to exit the euphotic zone, reducing production efficiency.
Solutions for Coastal Upwelling
- Strategies are necessary to address the issue of phytoplankton moving out of productive zones due to mixing.
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Description
Test your knowledge on upwelling concepts with these flashcards. Learn about the movement of nutrient-rich water and its significance in marine ecosystems. Ideal for students of oceanography or environmental science.
