Colourful Corals ‘Glow’ in Last, Desperate Bid to Survive in Warming Oceans

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Colourful Corals ‘Glow’ in Last, Desperate Bid to Survive in Warming Oceans

 

 

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Coral reefs in the Hawaiian Archipelago Papahanaumokuakea

 

Coral reefs can be found all across the world’s major oceans, the biggest ones found in the clear, shallow depths of tropics and the sub-tropics. As climate change threatens to collapse several

 

ecosystems across the globe, these beautiful reefs are likely to be among the first to fall in a warming world.

 

Recent research in the University of Southampton’s Coral Reef Laboratory has shown that the corals display a dazzling array of colour as they undergo bleaching—rapid discoloration of corals. The

 

study, published in the open-access journal Current Biology, shows that this ‘glowing’ is used as a defence mechanism against warmer ocean temperatures. Scientists say that the glowing colours

 

in bleached coral reefs preserve them like a ‘layer’ or a ‘shield’, similar to how humans apply sunscreen.

 

Corals—tiny, soft-bodied organisms that secrete calcium carbonate to build reefs—feed themselves by two unique ways. While some corals use small marine creatures like fish and plankton, most

 

depend on algae called ‘zooxanthellae’ which provides nearly 90% of coral’s energy through photosynthesis. This symbiotic relationship between the corals and the algae is what imparts the reefs

 

with enthralling, beautiful colours.

 

However, as the temperatures of the oceans across the globe increase relentlessly, coral polyps are forced to expel these algae and break this symbiosis to ensure short term survival. Once the

 

algae are gone, the coral loses its vibrant colour, thereby leaving a white exoskeleton look, which is known as ‘coral bleaching’.

 

Warming oceans, dying corals

 

 

As per estimates, since the 1970s, the oceans have absorbed more than 90 percent of the excessive heat trapped by carbon dioxide. The fact that oceans are huge and water takes a longer time to

 

heat up than air has eventually resulted in a warming of 0.11°C per decade on an average, with maximum warming happening near the surface.

 

Bleaching takes place when the tiny corals which release calcium carbonate for their protection suffer from extreme stressors like warm oceanic waters, pollution or acidification. While undergoing

 

bleaching, the corals display a wide array of beautiful colours, presenting a neon signal for the useful algae to return. Thus, the corals undergo deep forms of colouration within a span of 2 to 3

 

weeks after facing mild or harsh forms of heat stress.

 

Professor Jörg Wiedenmann, head of the University of Southampton’s Coral Reef Laboratory, explained: “If the coral cells can still carry out at least some of their normal functions, despite the

 

environmental stress that caused bleaching, the increased internal light levels will boost production of colourful, photoprotective pigments. The resulting sunscreen layer will then promote the

 

return of the symbiotic algae.”

 

The microscopic symbiotic algae zooxanthellae are released during the process within the tissues of corals. Being primary food for corals, if the algae fail to return to the corals the sooner they are

 

exposed to environmental stress, they can die gradually. This can lead to an entire coral reef ecosystem breaking down abruptly over the next few years, thus impacting the vast biodiversity that

 

depends on their complex structure.

 

 

Countries are currently looking for ways to preserve this vast species from dying due to threats from the climate. Commonwealth Nations are on the run for gaining access to the modes of satellite

 

technology to measure the health of corals. Commonwealth countries, accounting for nearly half of the world’s remaining tropical coral reef population, face potential threats from climate, and

 

consider it vital to protect coral reefs, as they act as a shield against storms and benefit tourism.

 

The new technology is expected to make use of high-resolution satellite images and data analyses to help scientists determine the threats, and to enable governments to take appropriate action.

 

Through the partnership of the Commonwealth with Vulcan Inc., a US-based group, the software would be made available to the countries free of cost. As per Baroness Patricia Scotland,

 

secretary-general of the Commonwealth, the work done by the Commonwealth Nations would have a huge impact on the protection of coral reefs that the countries are dependent on globally.

 

The Commonwealth demonstrated the project on this year’s World Oceans Day on June 8, with countries gearing up to save their precious waters and manage their resources in a sustained

 

manner. In one such solid step, the UK government has published a review of ocean protections that include setting up new safer marine areas, banning all fishing, dredging, oil drilling,

 

construction and other methods of ocean exploitation.

 

Corals are at extreme risk of extinction due to the prevailing climate crisis, with nearly half of them already approaching a point of no-return over the past decades. In the absence of decisive

 

action to reduce emissions, the fate of these ancient aquatic creatures looks grim.

 

Commonwealth countries step up conservation efforts