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Showing posts from March 12, 2014

Early oxygenation of deep ocean

Traditional theory has it that the origin of complex life on earth was catalysed by oxygenation of the atmospheric and ocean. Scientists now counter this argument to suggest that in fact they were the first life forms, such as sponges, which oxygenated the deep oceans and aided in the evolution of complex life forms. The ocean contained sufficient levels of oxygen to support life for over 1.5 billion years before the first animals evolved. Yet, the oxygen so found was restricted to the upper few metres of the ocean. The ocean depths, including the bottom of the water body, continued to remain anoxic till half a billion years ago. Central to determining the oxygen levels in deep oceans is the delicate balance between oxygen supply and demand. The demand shoots up when organic matter in the form of dead organic material settles to the bottom. Sponges that were found in the continental shelf of the ocean played a crucial role in reducing the oxygen demand by the dead organ…