What are ocean dead zones?

Dead zones get their name from the fact that they can support very few plants and animals. This is due to the absence of oxygen, known as ‘hypoxia’. Hypoxic conditions can materialise in lakes and other standing bodies of water, but they can also occur in large areas of the ocean. The main cause of a dead zone is eutrophication – when minerals, usually of agricultural origin, are washed into the water. The heightened nutrient levels stimulate huge blooms of algae on the surface of the water. This then restricts oxygen making its way into the water, which eff ectively smothers everything living beneath it. Due to the agricultural nature of the nutrient runoff , dead zones often appear close to the shore. There are around 146 known coastal dead zones around the world, with the largest ones located in the Baltic Sea and the Gulf of Mexico.

@askmenow