What is the Great Barrier Reef?

The Great Barrier Reef is the largest coral reef in the world, located off the coast of Queensland, Australia. This massive system of coral reefs covers a total area of 34,870,000 hectares, comprising of 900 islands, 70 bioregions and almost 3000 solo reefs. It is one of the natural wonders of the world and was nominated into the World Heritage List in 1981, for its exquisite characteristics and environmental significance. 

What is a coral reef? 
A coral reef is a chain of rocks, sands and coral skeletons lying at or near the surface of an ocean or a sea in a compact form. It is an aquatic ecosystem of its own, made up of colonies of coral polyps and groups of rocky coral cays bound together with calcium carbonate. 

Geographical significance 
Around 24 million years ago, the Australian region of Queensland started sidetracking into a tropical water zone facilitating the wide growth of corals in the region. This is how the Great Barrier Reef came into existence on the western margin of the Coral Sea basin, in the southwestern Pacific Ocean. The Great Barrier Reef Marine Park Authority is responsible for the conservation of this giant under water ecosystem. Their estimation suggests that the most ancient reef structures emerged almost 600,000 years ago, sometime around when dinosaurs existed. Over the years, with a rise in sea level, coral reefs have also expanded. Unfortunately, some islands got submerged in the process. However, it led to the formation of new corals above them.   

Ecological Significance 
The Great Barrier Reef is a natural habitat for a wide variety of marine plants and animals like: 215 species of birds, 330 species of ascidians, 125 species of sharks and stingrays, 49 species of pipefish, 9 species of sea horses, 7 species of frogs, nearly 5000 species of mollusks, 30 species of dolphins and porpoises, 1500 species of fishes and 17 species of sea snakes.  

Many species of endangered plants and animals also rely on nutrients and protection from the Great Barrier Reef like that of saltwater crocodiles and the flatback Olive Ridley Sea turtle. Every year, around 1.5 million birds migrate to the northern and the southern regions of the Reef, as it is their favourite breeding grounds. The Reef is also home to around 2200 species of plants, including woody plants in the northern islands and herbaceous plants in the southern islands.  

Environmental impact and climate change 
There are many manmade and natural threats to the survival of the Great Barrier Reef such as climate crisis, illegal fishing, pollution, shipping accidents, tropical cyclones and hazardous oil spills. The excessive warming of ocean water leads to coral bleaching that disrupts the algae living inside. Algae are responsible for providing corals their necessary nutrition. So, when they are threatened, corals begin to starve and perish. Between 2014 and 2016, the maximum amount of bleaching happened due to global warming, which killed almost half of the coral population in the Great Barrier Reef.