Dead zones (hypoxic i.e. oxygen deficient water) in the coastal zones are increasing, typically surrounding major industrial and agricultural centers. This is commonly occurring due to nutrient pollution, in the form of nitrogen and phosphorous leading to algal blooms and eutrophication.
From collection: In Dead Water - Climate Change, Pollution, Over-harvest, and Invasive Species in the World's Fishing Grounds
Hugo Ahlenius, UNEP/GRID-Arendal