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Due to the hypoxic conditions present in dead zones, marine life within these areas tends to be scarce. Most fish and motile organisms tend to emigrate out of the zone as oxygen concentrations fall, and benthic populations may experience severe losses when oxygen concentrations are below 0.5 mg l −1 O 2. [17]
The exaerobic zone is found at the boundary of anoxic and hypoxic zones. Hypoxia can occur throughout the water column and also at high altitudes as well as near sediments on the bottom. It usually extends throughout 20–50% of the water column, but depends on the water depth and location of pycnoclines (rapid changes in water density with depth).
In mountaineering, the death zone refers to altitudes above which the pressure of oxygen is insufficient to sustain human life for an extended time span. This point is generally agreed as 8,000 m (26,000 ft), where atmospheric pressure is less than 356 millibars (10.5 inHg; 5.16 psi). [ 1 ]
An hypoxic zone, also referred to as a dead zone, is formed ... creating an uninhabitable environment for some commercial marine life, and scientists are saying the sparse amount of tropical ...
A 'dead zone' off the Gulf coast is larger than NOAA predicted. The massive area poses danger to marine life, and recovery could take decades. A 'dead zone' is growing in the Gulf of Mexico.
The change has been fairly rapid and poses a threat to fish and other types of marine life, as well as to people who depend on marine life for nutrition or livelihood. [7] [46] [8] [9] As low oxygen zones expand vertically nearer to the surface, they can affect coastal upwelling systems such as the California Current on the coast of Oregon (US).
The physiological responses to high altitude include hyperventilation, polycythemia, increased capillary density in muscle and hypoxic pulmonary vasoconstriction–increased intracellular oxidative enzymes. There are a range of responses to hypoxia at the cellular level, shown by discovery of hypoxia-inducible factors (HIFs), which determine ...
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 environmental problem. [29] There are five main sources of nutrient pollution.