Global warming, Oxygen loss and their effects on marine lives Global warming, climate change, and th

Global warming, Oxygen loss and their effects on marine livesGlobal warming, climate change, and their effects on us and on our environment are familiar topics. The atmospheric gases carbon dioxide, oxygen, and nitrogen, in proper balance, are all important in maintaining life on earth.Greenhouse gases, like CO2, SO2, and NO2, are responsible for warming of the world’s oceans. By 2100, global average temperature is expected to warm at least twice as much (2.0°C to 4.5°C, estimated range) as it has during the last 100 years, associated with a sustained doubling of atmospheric CO2 concentrations (IPCC report, 2007). Warm water near the equator has 4 mg/L dissolved oxygen, whereas water at the poles which has twice as much oxygen at 9 mg/L. Warmer water also leads to heightened metabolic rates amongst organisms. Therefore, as waters warm, there will be less oxygen in the water and the high metabolic rates will make organisms want it even more. In the last 25 years, oxygen levels dropped by 30 percent with a rise in water temperature of the Pacific ocean which is quite alarming as further increase in temperature and more oxygen loss could turn regions like southern coasts of California into dead zones where nothing survives.Curtis Deutsch, University of Washington oceanographer, led his team on a study of four marine species with distinct distribution ranges to simulate the possible effects of global warming and oxygen depletion on specific cases. These species include: open-ocean inhabiting cod, rock crabs from coastal waters, seabreams from subtropical waters in the Atlantic, and eelpouts that are bottom dwellers and inhabit the shallow waters of higher latitudes towards the North Pole. These species are quite distinct from one another in terms of their morphologies, physiologies, and oxygen requirements. The scientists then used climate models to project how temperature changes and low oxygen concentrations are likely to impact these species by the year 2100.The researchers calculated the predicted oxygen requirements for each species including their metabolic rates and compared them to oxygen availability in these environments. The predicted increase in water temperature of a few degrees will further lower the oxygen content and force these species to shift from their natural habitats. Even today, these species are finding that their geographic ranges are becoming restricted, and according to this study by 2100 their habitats will shrink by a further 20 percent.According to marine biologist Prof Hans-Otto Pörtner, an author of this study, “thanks to evolution, the animals living in the Arctic and Antarctic Oceans have adapted to these conditions and will have little chance to adjust when the combination of warming and lower oxygen levels hits.” The local polar species will have to compete with immigrant species from warmer areas for resources and the inevitable fallout will be the migration or extinction of the losing species. Moreover, the local species were well adapted to their environment, but the immigrants may have their own requirements which the new habitat may not be equipped to fulfill, resulting in more die-offs.The effect will be seen in every level of the marine food chain. The low oxygen levels may not necessarily cause some species like sharks, marlins, and sailfish (in the picture), to migrate, but they may need to travel further to feed. They will feel an extra stress which may force them to alter their life style, feeding habits, and may also affect their reproduction rate. The prey-predator relationship dynamics will also be affected as predator fish will move towards shallower waters following their prey and will be themselves preyed upon by birds and humans while fishing. The more sturdy species will survive while those that have specialized requirements of food, habitat choice, and reproduction will be unable to withstand the stress and die.Brad Seibel, marine biologist and co-author of the study thinks many species worldwide will likely show similar effects. The shrinking habitats of marine species will profoundly affect the fishing industry worldwide and will have a huge impact on the world economy. The impact of global warming and oxygen depletion associated with climate change may ultimately result in the extinction of thousands of marine species. A global consensus on cutting down of greenhouse gases emissions (responsible for global warming) and also diligent utilization of natural resources may help protect some of these species from extinction by preserving their habitats.–RBFurther information: http://bit.ly/1KP1dDdhttp://bit.ly/1QdqM4qhttp://bit.ly/1N14EEGOn climate change: http://nyti.ms/1RsdaObhttp://bit.ly/1GAgDE9http://bit.ly/1QVU9ZzOn oxygen depletion: http://bit.ly/1KeHmNShttp://bit.ly/1BMKIowhttp://bit.ly/1SKZ0KAImage: http://bit.ly/1EhNCPjhttp://bit.ly/1H13lauReference: Deutsch, C. , Ferrel, A. , Seibel, B. , Portner, H.-O. , and Huey, R. B. (2015). Climate change tightens a metabolic constraint on marine habitats. Science, 2015; 348 (6239): 1132 DOI: 10.1126/science.aaa1605Brander, K. (2010). Impacts of climate change on fisheries. Journal of Marine Systems 79 (2010), 389–402. DOI: 10.1016/j.jmarsys.2008.12.015 -- source link

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