the sharks are straving to death and need people to eat because we have polluted their habitat and killed their food sources off with our life styles.
http://www.commondreams.org/headlines05/0515-05.htmIt has arrived early; it's bigger than ever and it promises a summer of death and destruction. The annual "dead zone" in the Gulf of Mexico - starved of oxygen, and thus killing fish and underwater vegetation - has appeared earlier than usual this year.
This is just one sign of a rapidly growing crisis. The number of similar dead zones in the world's seas has doubled every decade since 1960, as a result of increasing pollution. The United Nations Environment Program says that there are now 146 of them worldwide, mainly around the coasts of rich countries. Its executive director, Klaus Töpfer, calls their growth "a gigantic, global experiment ... triggering alarming, and sometimes irreversible, effects".
The Gulf of Mexico dead zone - which can cover more than 7,000 square miles - is mainly caused by fertilizers, flowing down rivers to the sea. Every year the Mississippi river - which drains 41 per cent of the United States - dumps 1.6 million tons of nitrogen in the gulf, three times as much as 40 years ago. Most comes from the highly productive corn belt, which helps to feed the world. The nutrients feed blooms of algae and phytoplankton. The algae drain oxygen from the water, as do the decomposing bodies of the plankton, when they fall to the seabed and die.
It hits a fishery that provides one-fifth of the country's entire harvest from the sea. As a result, catches of brown shrimp, the gulf's most important species, have dropped since 1990. The worst years match those with biggest dead zones, which appear to block juveniles from reaching their offshore spawning grounds. Last year, the dead zone was even blamed for a tripling in shark attacks on Texas bathers. Fish and swimming crabs flee the pollution for cleaner water, followed by the sharks.
Scientists recently found 19 locations with severely depleted oxygen in the gulf, where they expected to find none at this time of year. "It usually doesn't start until June," said Steven DiMarco, a researcher at Texas A&M University, one of several groups involved in the testing. "It was larger at that time than it was at any time in 2004. During January and February of this year, the flow of the Mississippi river was larger than at any time in 2004."
The stratification levels between the fresh river water and heavier salt water of the sea created the dead zone, which usually is at its most severe between 30 and 60 feet below the surface. The zone was first recorded in the early 1970s. It originally occurred every two to three years, but now returns each summer.
It has arrived early; it's bigger than ever and it promises a summer of death and destruction. The annual "dead zone" in the Gulf of Mexico - starved of oxygen, and thus killing fish and underwater vegetation - has appeared earlier than usual this year.
This is just one sign of a rapidly growing crisis. The number of similar dead zones in the world's seas has doubled every decade since 1960, as a result of increasing pollution. The United Nations Environment Program says that there are now 146 of them worldwide, mainly around the coasts of rich countries. Its executive director, Klaus Töpfer, calls their growth "a gigantic, global experiment ... triggering alarming, and sometimes irreversible, effects".
The Gulf of Mexico dead zone - which can cover more than 7,000 square miles - is mainly caused by fertilizers, flowing down rivers to the sea. Every year the Mississippi river - which drains 41 per cent of the United States - dumps 1.6 million tons of nitrogen in the gulf, three times as much as 40 years ago. Most comes from the highly productive corn belt, which helps to feed the world. The nutrients feed blooms of algae and phytoplankton. The algae drain oxygen from the water, as do the decomposing bodies of the plankton, when they fall to the seabed and die.
It hits a fishery that provides one-fifth of the country's entire harvest from the sea. As a result, catches of brown shrimp, the gulf's most important species, have dropped since 1990. The worst years match those with biggest dead zones, which appear to block juveniles from reaching their offshore spawning grounds. Last year, the dead zone was even blamed for a tripling in shark attacks on Texas bathers. Fish and swimming crabs flee the pollution for cleaner water, followed by the sharks.
Scientists recently found 19 locations with severely depleted oxygen in the gulf, where they expected to find none at this time of year. "It usually doesn't start until June," said Steven DiMarco, a researcher at Texas A&M University, one of several groups involved in the testing. "It was larger at that time than it was at any time in 2004. During January and February of this year, the flow of the Mississippi river was larger than at any time in 2004."
The stratification levels between the fresh river water and heavier salt water of the sea created the dead zone, which usually is at its most severe between 30 and 60 feet below the surface. The zone was first recorded in the early 1970s. It originally occurred every two to three years, but now returns each summer.
CONSERVATION SCIENCE INSTITUTE quality science for conservation. Dead Zones
http://www.conservationinstitute.org/deadzones.htmEvery summer in the Gulf of Mexico an area, sometimes as large as Massachusetts, becomes void of life due to severely depleted levels of oxygen in the Gulf's water, a state known as hypoxia. This condition kills every oxygen-dependent sea creature within its 8,500 square mile zone. The dead zone varies in size, but it has been growing steadily since 1993. The dead zone is caused by excess nitrogen and phosphorous that is washed into the Gulf from the Mississippi River. These nutrients ignite huge algae and phytoplankton blooms. As the blooms die, they drop to the ocean floor and decompose, using up the oxygen of the deeper water. The stratification of the water that occurs during the summer in the Gulf prevents the deepest water from becoming reoxygenated. As a direct result, oxygen levels fall below 2 parts per million, a level that most marine life cannot survive, including all commercial fish, crab and shrimp species. The dead zone is now one of the largest hypoxic zones of water in the world.
The excess nutrients (nitrogen and phosphorus) result from human activities in the upstream Mississippi River watershed. The principal areas contributing nutrients to the Mississippi River, and ultimately to the Gulf, are streams draining the corn belt states, particularly Iowa, Illinois, Indiana, Ohio, and southern Minnesota.
Dead zones in the world's oceans and seas that are starved for oxygen number some 150 throughout the world, according to a new report by the United Nations Environment Programme. Linked to an excess of nitrogen from agricultural fertilizers, vehicle fumes, factory emissions and wastes, dead zones do not have enough oxygen in the water for fish, oysters and other marine creatures to survive.
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