Changes in Ocean Currents

Why does warmer, less salty water float above colder, saltier water?

Because it is less dense.

What is upwelling?

When deeper nutrient-rich water rises as layers mix due to currents, wind, and tides.

What causes reduced mixing in the ocean?

Less movement from currents, winds, or tides.

What is the effect of more stability between ocean layers?

Less nutrient and gas exchange between layers.

Why is nutrient upwelling important?

It brings nutrients to the surface to support consumers and nutrient cycling.

Why is the ocean surface the most active zone?

Because sunlight only penetrates to this layer.

How does carbon-containing detritus reach the deep ocean?

It sinks by gravity.

Why does surface water become less dense?

Due to warming and melting ice.

What causes increased ocean stratification?

Atmospheric warming.

How does ocean stratification affect mixing?

It hinders mixing of heat, oxygen, and carbon dioxide.

How does stratification affect marine ecosystems?

It reduces nutrient circulation and harms ecosystems.

Why does warmer water increase atmospheric CO2?

Because it absorbs less CO2, leaving more in the atmosphere.

How does warmer water affect oxygen content?

It absorbs less oxygen and mixes it less into deep waters.

How does low oxygen harm marine life?

It damages marine organisms and increases coral bleaching.

Why is the surface layer the most biologically active?

Because sunlight drives photosynthesis there.

How does photosynthesis affect the carbon cycle in oceans?

It captures carbon, which enters the marine food chain.

What happens to organic carbon like detritus and faeces?

It sinks and mixes into deeper ocean layers.

What do deep ocean currents bring to continental shelves?

Nutrients.

How does upwelling affect marine ecosystems?

It supports marine productivity and food chains.

How do climate anomalies affect upwelling?

They reduce upwelling, lowering marine productivity and energy flow.