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This type of ocean deoxygenation is also called dead zones. Secondly, ocean deoxygenation occurs also in the open ocean. In that part of the ocean, there is nowadays an ongoing reduction in oxygen levels. As a result, the naturally occurring low oxygen areas (so called oxygen minimum zones (OMZs)) are now expanding slowly. [4]
Dead zones can be classified by type, and are identified by the length of their occurrence: [16] Permanent dead zones are deep water occurrences that rarely exceed 2 milligrams per liter. Temporary dead zones are short lived dead zones lasting hours or days. Seasonal dead zones are annually occurring, typically in warm months of summer and autumn.
Dead zones occur in the ocean when phosphorus and nitrogen from fertilizers in land runoff cause excessive growth of microorganisms, which depletes oxygen and kills fauna. Worldwide, large dead zones are found in coastal areas with high human population density.
Every spring, an area appears when the water doesn't have enough oxygen to support fish and other marine life.
The Oregon coast is known for its stunning beauty. "Our family fishing boat, the Timmy Boy, has just come in from a trip fishing for sablefish," says fisherman Bob Eder. Eder says this abundant ...
Dead zones are hypoxic, meaning the water has very low levels of dissolved oxygen. This kills off marine life or forces it to leave the area, removing life from the area and giving it the name dead zone. Hypoxic zones or dead zones can occur naturally, but nutrient pollution from human activity has turned this natural process into an ...
The Atlantic Ocean is teeming with life, but for the first time researchers have discovered dead zones in these waters - areas low in both oxygen and salinity - off the coast of Africa. Fish can't ...
Human activities in the Holocene epoch, such as the release of nutrients from farms and sewage, cause relatively small-scale dead zones around the world. British oceanologist and atmospheric scientist Andrew Watson says full-scale ocean anoxia would take "thousands of years to develop."