The Arabian Sea faces an increased frequency and duration of marine heatwave days

Marine Heatwaves

A marine heat wave is often characterized as a coherent region of extremely warm sea surface temperature that lasts for days to months.
Marine heat waves occur when sea temperatures are higher than usual for a lengthy period of time.
Over the last decade, MHWs have been recorded in all major ocean basins.
These occurrences are connected to coral bleaching, seagrass damage, and kelp forest loss, all of which have a negative impact on the fishing industry.

Causes of marine heatwaves

Summer/ Winters – Heat Waves can occur in both the summer and the winter, when they are referred to as “winter warm-spells.”
- These winter occurrences can have serious repercussions, such as in Australia’s southeast, where the spiny sea urchin can only colonize farther south when winter temperatures top 12 °C.
Ocean Currents – The most common source of marine heat waves is ocean currents, which may build up patches of warm water and air-sea heat flux, or warming via the ocean surface from the atmosphere.
Winds – Sunlight normally penetrates the atmosphere and heats the ocean’s surface. When there are light winds, the warm water does not mix with the cooler water below.
- It floats on the surface of the water and continues to heat up, resulting in marine heat waves.
Climate Change – Large-scale climate influences such as the El Nino Southern Oscillation (ENSO) can too cause marine heatwaves.
- An iconic heatwave event was in 2015. It encapsulated most of the Indian Ocean and coincided with the strong El Niño year, causing widespread coral bleaching in the Lakshadweep archipelago.

Impacts of marine heatwaves

Habitat Destruction – Marine heatwaves can alter the habitat ranges of some species, such as the spiny sea urchin off the coast of southeastern Australia, which has been moving southward towards Tasmania at the expense of the kelp forests on which it feeds.
Loss of Biodiversity – Marine heatwaves can have a significant impact on biodiversity. Marine heatwaves in northern Australia caused widespread bleaching of the Great Barrier Reef in 2016.
Deoxygenation and Acidification – Marine heatwaves frequently occur in conjunction with other factors such ocean acidification, deoxygenation, and overfishing. Marine Heatwaves not only wreak more havoc on ecosystems, but they also raise the danger of deoxygenation and acidification.
Economic Loss – Marine heatwaves can result in economic losses due to their effects on fisheries and aquaculture. The abalone harvest in Western Australia’s north was damaged by a maritime heatwave in 2011.
Alter the Ecosystem Structure – Marine heat waves influence ecosystem structure by promoting certain species and inhibiting others. It has been linked to mass death of marine invertebrates and may drive animals to shift their behavior, putting them at greater danger of injury.