BLEACHING HITS WORLD’S SOUTHERNMOST CORAL REEF:
What’s in news?
Recently, the scientist Bill Leggat of the University of Newcastle said, because of the climate change, the world’s southernmost coral reef has been affected.
- Because of climate change and global warming, the surface sea temperature is rising which hits the Corals off Lord Howe Island, which is 600KM far from the mainland Australia. The Corals in this island was affected with Bleaching.
- Also this was affected due to rise in baseline temperature caused by climate change and the local factors such as elevated temperatures.
- In 2016 and 2017, severe bleaching was occurred in the Great Barrier Reef, but the Coral off Lord Howe Island was escaped. But this year it was get affected. This shows Climate change is influencing every minor part of the world.
- The scientist also found that, severe bleaching of up to 90% at Lords Howe’s inshore and shallow lagoon reefs.
- Deeper water corals in the marine parks, hold species which can’t be found anywhere else in the world.
- Coral reefs evolved over the past 200 to 300mn years, are the largest living structure on the planet, and the only living structure to be visible from space. Coral reefs are therefore created by millions of tiny polyps forming large carbonate structures, and are the basis of a framework and home for hundreds of thousands, of other species.
- Coral reefs only occupy 1% of the area of the ocean but they support 25% of all marine life on the planet.
- Coral polyps have developed symbiosis relationship with tiny single-celled plants, known as Zooxanthellae, is a microscopic, single-celled algae lives inside the tissues of each coral polyp, sharing space, gas exchange and nutrients to survive.
- Corals are found all over the world’s oceans. The biggest coral reefs are found in the clear, shallow waters of the tropics and subtropics. The largest of these coral reef systems, the Great Barrier Reef in Australia, is more than 1,500 miles long (2,400 kilometers)
- Hard Corals and Soft corals: The coral species that build reefs are known as “Hermatypic, or Hard corals” corals because they extract calcium carbonate from seawater to create a hard, durable exoskeleton that protects their soft, sac-like bodies. Other species of corals that are not involved in reef building are known as “Soft corals”.
- The corals look like Fringing reefs, Barrier reefs, Atolls. These coral reefs are important because Hundreds of millions of people rely on coral reefs for essential nutrition, livelihoods, protection from life-threatening storms and crucial economic opportunity.
- Variety of life associated with coral reefs.
- Main threats to coral reefs are;
- Climate change, overfishing, unsustainable coastal development, pollution, destructive fishing practice, careless tourism, coral mining.
What is Bleaching?
- When the abnormal environmental conditions, such as rise in sea temperature, Ocean Acidification, Solar radiation and ultraviolet radiation, Infectious Diseases, Increasedsedimentation, etc., occurs, which results in expelling the symbiotic algae zooxanthellae living in their tissues, causing them to turn completely white. This phenomena is called coral bleaching.
- The pale white colour is of the translucent tissues of calcium carbonate which are visible due to the loss of pigment producing zooxanthellae.