Which mechanism causes oxygen depletion in deep ocean layers during thermohaline circulation slowdown?

💡 Explanation

When thermohaline circulation slows, the reduced mixing decreases transport driven by density, which decreases replenishment of oxygenated surface water to depth and nutrient transport to surface. Therefore reduced mixing is the causal mechanism rather than nutrient levels, organic decomposition, or enhanced oxygen solubility which would act in other situations.

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