Global warming reducing phytoplanktons in western Indian Ocean

Rapidly decreasing presence of marine phytoplankton, a micro-algae consumed by small fish and responsible for reducing carbon dioxide in sea water, in the western Indian Ocean due to global warming may reduce the oceanic region to an ecological desert, scientists have warned.

A joint study conducted by scientists at the Indian Institute of Tropical Meteorology in Pune and the National Institute of Oceanography (NIO) in Goa has revealed the quantum of phytoplankton has witnessed an alarming decrease at the rate of 20 percent over the last six decades.

Earlier studies had described the western Indian Ocean as a region with the largest increase in phytoplankton during the recent decades. On the contrary, the current study points out an alarming decrease of up to 20 percent in phytoplankton in this region over the past six decades, says the study led by Matthew Roxy, a climate scientist at the Pune-based institute.

The study has pointed out that the drop in phytoplankton in the western Indian Ocean is particularly alarming, because the oceanic region hosts one of the largest concentrations of marine phytoplankton blooms in summer.

"Interestingly, this is also the region with the largest warming trend in sea surface temperatures in the tropics during the past century - although the contribution of such a large warming to productivity changes has remained ambiguous," the study points out.

The report also warns that the Indian Ocean may be reduced to an ecological desert, given the levels of ocean warming.

"We find that these trends in chlorophyll are driven by enhanced ocean stratification due to rapid warming in the Indian Ocean, which suppresses nutrient mixing from subsurface layers. Future climate projections suggest that the Indian Ocean will continue to warm, driving this productive region into an ecological desert," the study says.

Scientists at the Goa-based NIO have already warned of a potential fish famine off the coast of Goa, due to over-fishing and excessive pollution in the waters of India's western state.