Is there impact of climate change on biological productivity in the Indian Ocean

Abstract

SeaWiFS derived eight days average, chlorophyll images for 10 years from 1997 onward have been analysed, representing the present situation. Few representative locations in the Arabian Sea and Bay of Bengal were studied to understand the chlorophyll variability. Chlorophyll values are generally higher during 2000’s as compared to that of during the 1980’s. In order to study the expansion or contraction of area under low or high chlorophyll region, the image was classified into three zones viz. oligotrophic, mesotrophic and eutrophic waters based on chlorophyll range. A comparison is made of average values from October to April in CZCS derived (1980’s) and SeaWiFS derived (2000’s) chlorophyll images. Chlorophyll concentration in the northwest Arabian Sea has increased significantly during the 2000’s as compared to that of 1980’s and the area under eutrophic zone i.e. chlorophyll rich waters has increased in spatial extent. An increase in chlorophyll concentration in this decade, as compared to two decades back, indicates a positive sign, against the reported global warming.