Sunday, July 18, 2010

Air pollution kills phytoplankton in Bay of Bengal: Major change in phytoplankton composition off the coast of Visakhapatnam

By Syed Akbar
Hyderabad, July 9: Increasing vehicular pollution has triggered changes in phytoplankton populations in the Bay of Bengal, upsetting the delicate composition of the surface sea waters.
Phytoplanktons are a major source of oxygen on the earth and serve as feed for aquatic animals. Any disturbance in phytoplankton community will have severe environmental consequences including death of sea animals and drastic fall in the oxygen levels on the earth.
Experiments conducted by the National Institute of Oceanography, Visakhapatnam regional centre, showed that the Bay of Bengal phytoplankton are quite sensitive to increasing carbon dioxide from vehicular and industrial emissions.
"Future change in surface sea water carbonate chemistry might significantly affect the eco-physiology of the natural phytoplankton, which can have a significant impact on the biogeochemistry of this part of the tropical ocean," the NIO has warned.
The NIO group comprising H Biswas, T Acharyya, V Venkat Ramana and D Bandyopadhyay and Alexander Cros from France, noticed that the diatom dominated population was found to be replaced by cyanobacteria under high carbon dioxide and nutrient limited condition. The results were released at the ongoing Asia Oceanic Geosciences Society meeting in the city.
Particulate organic matter, dissolved oxygen, dissolved organic carbon was found to be increased with increasing carbon dioxide. Almost 2.7 times higher total bacterial count was observed in the highest carbon dioxide treated cells.
The surface ocean absorbs carbon dioxide released by vehicles and industries. This changes the surface ocean carbonate chemistry by lowering the pH, through a process called ocean acidification.
"The surface sea water pH is going to be affected in such a level which has not been experienced in last hundred million years by the world ocean. Marine and estuarine phytoplankton are the key group responsible for ocean primary production and therefore, has a great control on the global carbon sink of atmospheric carbon dioxide," said Biswas.
The NIO team conducted what is called bottle experiment with the natural phytoplankton population of Bay of Bengal to test the effect of increasing carbon dioxide on them. This is the first-ever major study on the carbon dioxide effect on a tropical ocean.

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