Coral reefs could experience mass bleaching


The record rise in ocean temperatures has experts on high alert. Now, the US National Oceanic and Atmospheric Administration (NOAA) has issued a worrying warning. We are about to witness the fourth mass coral reef bleaching event.

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Coral bleaching can be catastrophic for the entire ocean ecosystem (Image: Enessa Varnaeva/Shutterstock)

Coral bleaching: impact on the entire ocean ecosystem

According to scientists, the phenomenon is caused by excessive warming of the sea and can result in the death of organisms spread across extensive areas of tropical reefs, including parts of Australia's Great Barrier Reef.

“We are literally on the brink of the worst bleaching event in the history of the planet,” warned NOAA. The agency added that the entire Southern Hemisphere is expected to suffer from the phenomenon this year.

Triggered by heat stress, bleaching occurs when corals expel the colorful algae living in their tissues. Without them, organisms become pale (without their bright colors) and vulnerable to disease and hunger, as much of their energy comes from photosynthesis carried out by these algae.

As corals are huge refuges for fish and other species, the phenomenon can be catastrophic for the entire ocean ecosystem. Furthermore, it should impact fishing and tourism, which depend on healthy and colorful reefs to attract divers. The information is from Folha de São Paulo.

Dead corals after undergoing a bleaching process (Image: OSJPHOTO/Shutterstock)

El Niño enhanced the phenomenon

  • The last global mass bleaching event occurred from 2014 to 2017, when the Great Barrier Reef lost almost a third of its corals.
  • Preliminary results suggest that about 15% of the world's reefs had high mortality rates during the period.
  • This year, the scenario could be even worse.
  • Following last year's Northern Hemisphere summer, the Caribbean experienced its worst coral bleaching on record.
  • Now, the situation is repeating itself and escalating in the other half of the planet.
  • According to researchers, El Niño exacerbated the problem.
  • For an event to be considered global, widespread bleaching must occur in three ocean basins: Atlantic, Pacific and Indian.
  • Scientists evaluate sea surface temperature data and satellite imagery to determine whether reef pixels are exceeding key thresholds for the phenomenon.


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