The Great Barrier Reef has lost nearly half of its corals in the last two decades.
Australia is most famous for its natural wonders like Uluru, MacKenzie Falls, Shark Bay, the Twelve Apostles, the Great Barrier Reef, and many other dramatic mountain ranges.
The “State Icon” of Queensland stretches almost 2,300 km and has nearly 2,900 individual reefs. It is known to support a wide range of fish and other sea organisms, gaining a place on the World Heritage Site in 1981.
Apart from being the world’s biggest single structure made out of living organisms, it is also visible from outer space. However, the Great Barrier Reef today is now facing threats due to the rising sea temperatures caused by climate change.
What does the study say?
ARC Centre of Excellence for Coral Reef Studies researched the coral populations and found that nearly 50% of it has vanished. The assessment was based on the colony length and size along the reef.
The co-author of the report, Terry Hughes, stated a huge decline in the small, medium, and large corals population since the 1990s. This was also observed both in shallow and deep reefs.
The results from the tests depicted that the reef’s ability to regenerate and recover is also low. Further observations stated that the number of larvae, baby corals, and breeding adults found was also low in number.
The effects of coral bleaching
The main reason for the decreasing populations is the coral bleaching effect. It’s termed that way as the coral primarily has a skeleton made of calcium carbonate. This is further covered by zooxanthellae giving vibrant colors to the organisms.
As the waters’ temperatures increase, the dinoflagellates start detaching from the corals as a stress response giving it a white bleached look. This doesn’t kill the coral immediately, but if the temperatures continue to rise, the end effect is agitating.
From the areal survey conducted, 39% had little or no bleaching, 35% had a moderate effect, and 25% were severely affected. The pale and lightly affected ones can regenerate if the temperatures go back to normal.
Striking an imbalance underwater
Since 1995, the reefs have experienced five mass bleaching effects. Starting from 1998, followed by 2002, 2016, 2017, and in 2020. Of the five years, 2016 and 2020 saw the worst coral bleaching effects so far.
Experts also found that branching and tablet-shaped corals were amongst the most affected. These also provide habitat for many other fish species like Yellow Tang, Damselfish, Sea Horses, Butterflyfishes, and more.
Researchers believe that the depleting coral reefs will strike a great imbalance in the marine ecosystem.
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