Movement of cold water to the surface to replace warmer water and bring tiny organisms, minerals, and other nutrients from deep ocean layers is called what?

• A. Upwellings
• B. Downwellings
• C. Tides
• D. Eddies

Answer: (A)

Upwelling is the vertical movement that brings deeper, colder water up to the surface, replacing the warmer surface water. This brings nutrients, minerals, and microscopic organisms from the deep ocean into sunlit zones where phytoplankton can thrive, fueling the base of the marine food web and supporting abundant fisheries. The process is often driven by winds and the Coriolis effect, which push surface water away from the coast and allow deeper water to rise (a mechanism known as Ekman transport). In contrast, downwelling involves sinking surface water, which moves nutrients away from the surface; tides are regular rises and falls due to gravity from the moon and sun and aren’t the nutrient-bringing mechanism described; eddies are rotating currents that mix water but aren’t the primary means of lifting deep water to the surface.