20 December 2016 Current Affairs: Scientists have discovered a huge dead zone in the Bay of Bengal. The area, estimated to be around 60000 square km, is reported to contain little or no oxygen.
The area is also said to host microorganisms, which remove a large amount of nitrogen from the ocean. Though dead zones can be found in other oceanic bodies as well, there has been no indication of nitrogen loss there.
Researchers from the Council of Scientific and Industrial Research’s National Institute of Oceanography reported that though some amount of oxygen does exist in the Bay of Bengal, the concentrations are lesser that what standard techniques could detect.
The oxygen level is stated to be around 10000 times lesser that the amount found in the air-saturated surface waters.
The microbes present in the Bay of Bengal are in fact capable of removing all the nitrogen from the water but traces of oxygen stop them from doing so.
Though there is some evidence of nitrogen-removing microorganisms existing in other well-known dead zones well, they are reported to work at a much slower rate.
According to Wajih Naqvi, the former director of National Institute of Oceanography (NIO), if the last amount of oxygen is removed from the ocean then, the bay would become a cause of nitrogen removal from oceans across the world.
Complete removal of nitrogen could affect the nitrogen balance in marine life and also the rate of their productivity.
Dead zones : Dead zones are large areas in the ocean that have low oxygen concentration. The marine life in these areas mostly suffocates and dies or if they are mobile like the fish then, they leave the area.
Though at many times, dead zones occur naturally, scientists are also of the opinion that they are created due to increased human activity.
The main cause of the zones created by humans is nutrient pollution. Excess nutrients (nitrogen and phosphorus) can result in the overgrowth of algae, which later decomposes in the water consuming excess oxygen, depleting the supply available for the marine life.
Dead zones can be found in virtually every oceanic body, the largest encompassing almost the whole bottom of the Baltic Sea. Another large dead zone is located in the Gulf of Mexico. Other dead zones occur off the western coasts of North and South America and off the coast of Namibia and western coast of India.
Global warming triggered by climate change is predicted to lead to an expansion of these dead zones. However, it is not certain whether the climate change would lead to the removal of the last traces of oxygen from the bay as well.