Marine heatwaves are periods of extremely high temperatures in the ocean. This phenomenon causes ocean temperatures to be extremely warm for an extended period that can have significant impacts on marine ecosystems and industries.? These can occur in summer or winter.
The most common drivers of marine heatwaves include:
- Ocean currents can build up areas of warm water.
- Air-sea heat flux or warming through the ocean surface from the atmosphere.
- Winds can enhance or suppress the warming in a marine heatwave, and climate phenomena like El Niño can change the likelihood of events occurring in certain regions.
Marine heatwaves affect ecosystem structure, by supporting certain species and suppressing others. They can change the habitat ranges of certain species. Many animals tend to deter from their normal range by following the warm waters of the heatwave. The impact on fisheries and aquaculture is also significant. Emerging studies have reported their occurrence and impacts in the global oceans, but are little understood in the tropical Indian Ocean.
These events are linked to coral bleaching, seagrass destruction, and loss of kelp forests, affecting the fisheries sector adversely. An underwater survey showed that 85% of the corals in the Gulf of Mannar near the Tamil Nadu coast got bleached after the marine heatwave in May 2020. The Western Indian Ocean region experienced the largest increase in marine heatwaves at a rate of about 1.5 events per decade, followed by the North Bay of Bengal at a rate of 0.5 events per decade.JPSC Notes brings Prelims and Mains programs for JPSC Prelims and JPSC Mains Exam preparation. Various Programs initiated by JPSC Notes are as follows:-
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