Author(s): Raj Vir Singh Ojha

Abstract: Major oceans of the world, Atlantic, Pacific, Indian, Arctic and Antarctic cover approximately 70 percent of the earth’s surface. Each ocean indeed represents a very large and stable ecosystem. Marine ecosystems are very diversified and involved in a complicated net of internal and external intercommunications. Their evolutionary history and present adaptive possibilities strongly depend on variability of climate conditions. Ocean basins in equatorial, tropical, and moderate zones are distinguished by the stability of environmental parameters and less affected by climatic anomalies. On the contrary, polar oceans were the arena of significant ecosystem changes in the geological past, and their response to natural and anthropogenic impacts is essential in many respects. Climate induced changes and other less-understood anthropogenic changes will be superimposed on other impacts resulting from human activities such as over fishing, pollution, damming of rivers and habitat loss in coastal areas. Consequently, the fundamental characteristics of marine ecosystems, some already under stress, will be altered. Whether overall global yield from marine fisheries will decline due to climate change remains unclear; however, regime shift within individual marine ecosystems and trends in fish landing for certain species will likely occur. Calcareous plankton and coral are already suffering because of more acidic and warmer seawater. Global warming as a whole is favourable for primary production and therefore for increase in biological productivity on all ecosystem levels.

Pages: 198-200  |  955 Views  133 Downloads

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