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1·When surface waters are cold, deeper depths are allowed to upwell, bringing these essential nutrients toward the surface where the phytoplankton may use them.

当海水表面温度下降时，较深一些的海水就会上浮，同时把这些必须营养成分带到水面处，供生活在那里的浮游植物生长的需要。

2·However, when surface waters are warm (as during an el ni? O), they do not allow the colder, deeper currents to upwell and effectively block the flow of life-sustaining nutrients.

可是，如果海面水温较高(例如在厄尔尼诺期间)，深层海水就无法上流，从而大大阻断了这些生命必须营养的正常循环。