Massive Phosphate Runoff & Warming Ocean Temps Suck The Oxygen Out of the Seas
WHAT IS A DEAD ZONE?
A Dead Zone is an area of water with a Hypoxic bottom, which is to say, a lifeless, oxygen-starved place where nothing can live. When we say "area", we don't mean a small anomaly, but rather a lifeless no go zone for marine life measured in square miles. The Dead Zone in the Gulf of Mexico sometimes covers an area the size of New Jersey.
Dead Zones are caused by the large scale run-off of phosphate fertilizers, sewage, animal wastes and pollutions from the burning of fossil fuels into oceans, gulfs and other bodies of water. The algal blooms that cause dead zones are triggered by nutrients from this runoff. The low levels of oxygen in the water make it impossible for fish, oysters and other marine creatures to survive. These hypoxic conditions also kill off sea grass beds, which serve as habitats for marine life.
The massive algae blooms die and sink to the bottom, where it is consumed by microbes, which consume oxygen in the process. More algae means more oxygen-burning, and thereby less oxygen in the water, resulting in a massive flight by those fish, crustaceans and other ocean-dwellers able to relocate as well as the mass death of immobile creatures, such as clams or other bottom-dwellers. And that's when the microbes that thrive in oxygen-free environments take over, forming vast bacterial mats that produce hydrogen sulfide, a toxic gas.
CAN WE BLAME HUMANS? YES INDEED!
In the Gulf of Mexico dead zone, for example, agricultural runoff from the farmlands of central U.S, travel down the Mississippi. The phenomenon was first noted in the 1970's, about the time that monocultural agriculture began on a massive scale. A single low-oxygen event (known scientifically as hypoxia) off the coasts of New York State and New Jersey in 1976 covering a mere 385 square miles (1,000 square kilometers) of seabed ended up costing commercial and recreational fisheries in the region more than $500 million. As it stands, roughly 83,000 tons (75,000 metric tons) of fish and other ocean life are lost to the Chesapeake Bay dead zone each year—enough to feed half the commercial crab catch for a year.
Since then, the number of dead zones in the world's oceans and seas has increased dramatically, endangering fish stocks and the people who depend on them for food and livelihoods, the United Nations Environment Program (UNEP) warned Thursday. The latest study finds at least 435 dead zones across the world, up dramatically from previous years.
Some of the earliest recorded dead zones were in places like Chesapeake Bay in the United States, the Baltic Sea, the Kattegat, the Black Sea and the northern Adriatic Sea. The best known area of depleted oxygen is in the Gulf of Mexico - directly linked to massive agricultural nutrients or fertilizers brought to the Gulf by the Mississippi River.
In 2011 new dead zones were recorded in Finland's Archipelago Sea, the Fosu Lagoon in Ghana, the Mersey Estuary in the United Kingdom and Uruguay's Montevideo Bay. Others have been appearing off South America, China, Japan, south-east Australia and New Zealand.
GLOBAL DEAD ZONES
STUDY IDENTIFIES DE-OXYGENATED LEVELS AT 20% - 30% OVER PAST 50 YEARS [Dec 2015]: Warmer water holds less oxygen, which accounts for an accelerating rate of oxygen depletion into new zones in the open ocean.FIRST DEAD ZONES DISCOVERED IN OPEN OCEAN [June 2015]: Large dead zone or dead pool whirlpools are now evident in satellite analyses of the Atlantic Ocean off of West Africa. Unlike coastal dead zones, such as the one in the Gulf of Mexico, this dead zone moves with ocean currents. When it engulfs a fishery, the fish die.
Researchers report that for the first time, they are finding areas of extremely low oxygenated water, called "dead zones" off the coast of Africa. The dead zone just measured contains less oxygen than any previously recorded. Dead zones are so named because, low in both oxygen and salinity, within them fish cannot survive and suffer massive die-offs, especially when dead zones approach coastal areas. Virtually no sea life can survive in the one just found off the coast of southern Africa, and, unusual for these formations, it is moving, destroying all life in its path.
Read the original source: http://www.unknowncountry.com/news/devastating-dead-zone-africa#ixzz3dzKl4aOk
There are over 405 official dead zones around the world, not the least among them those dotting nearly the entire east and south coasts of the United States. Most Western rivers within agricultural or urban areas also sport dead zones at their mouths. In the Baltic Sea, one of the world's most prominent dead zone now features a bottom area which lacks oxygen year-round.
Nitrogen exports to the marine environment from rivers, for example, are expected to rise globally by 14 per cent by 2030 when compared with the mid 1990s.
However, Dead Zones are able to come back to life once fertilizer and other pollution is no longer dumped into them. It's amazing really. For example, in what amounts to a real life laboratory demonstration, the Black Sea dead zone, previously the largest dead zone in the world, largely disappeared between 1991 and 2001 after fertilizers became too costly to use following the collapse of the Soviet Union and the demise of centrally planned economies in Eastern and Central Europe. This also made room for the Gulf of Mexico Dead Zone to become numero uno.
Similarly, from 1985 to 2000, the North Sea dead zone had nitrogen reduced by 37% when policy efforts by countries on the Rhine River reduced sewage and industrial emissions of nitrogen into the water.
For more on the global water crisis, visit the Water Map
2015 Blew out all records for hottest global temperatures ever.