ANSWER WRITING_GS-1 - GEOGRAPHY (CORAL REEFS)

Q2. Explain the different types of corals. Also explain the challenges and threats faced by corals.

 Ans: Coral reefs are the underwater colonies of tiny living creatures that are formed of coral polyps held together by calcium carbonate & are usually found in shallow waters.

                                            Fig: Types of Coral Reefs

Types:

●      Fringing Reef: It is a coral line platform lying close to the shore extending outwards from the mainland. E.g. South Florida Reef, Andaman and Nicobar group islands.

●      Barrier Reef: Considered as largest of all the reefs, they develop off the coast and parallel to the shore as a broken and irregular ring. E.g. Great Barrier Reef of Australia, Mannar Barrier Reef.

●      Atoll: It can be defined as a reef that is roughly circular and surrounds a large central lagoon. E.g. Fiji Atolls, Bangaram atoll in Lakshadweep.

Threats:

When corals face stress by changes in conditions such as temperature, light, or nutrients, they expel the symbiotic algae zooxanthellae living in their tissues, causing them to turn completely white. This phenomenon is called coral bleaching. The factors leading to coral bleaching and causing a threat to corals are:

●      Climate Change:

➔   Global warming:

➢   As corals have a narrow temperature tolerance, rise in temperature causes coral bleaching.

➢   The rise in sea level due to melting of glaciers makes the coral go deeper underwater where they receive less sunlight.

➔   Stronger storms: Breaks coral branches and overturn coral colonies.

➔   Ocean Acidification: With increased CO2 in the water, corals form weaker skeletons, making them more vulnerable to disease and destruction by storms.

➔   Ozone depletion: The increased UV radiation can damage corals in shallow waters.

●      Overfishing can alter food-web structure and cause cascading effects, such as reducing the numbers of grazing fish that keep corals clean of algal overgrowth.

●      Destructive fishing practices such as purse seining, fine-mesh fishing, ‘moxy’ nets, cyanide fishing and blast fishing

●      Water pollution: Increased concentrations of various chemical contaminants and oil causes coral bleaching.

●      Coral mining & harvesting: Coral pieces are removed & heavily harvested for use as bricks, cement, jewellery, souvenirs, etc.

●      Unsustainable tourism: Snorkelling, diving, boating, overexploitation of reef species as food, for aquaria and as curios for tourist markets threatens the survival of species.

●      Sedimentation: Erosion caused by construction, mining, logging, and farming increases sediment in rivers. This drastically reduces the amount of light reaching coral reefs and destroys them.

●      Mangrove destruction: Mangrove forests are being rapidly destroyed through logging for firewood and clearing to create open beaches and aquaculture farms leading to sedimentation.

●      Indiscriminate exploitation of coral reefs for wildlife trade.

●      Massive outbreaks of predatory starfish, invasive species.

 

Coral reefs are also regarded as the tropical rainforest of the sea and occupy just 0.1% of the ocean’s surface but are home to 25% of marine species. They provide a variety of ecosystem services like fishing, tourism, subsistence food, etc. Clearly, their disappearance will have economic, social and health consequences.

So, the need of the hour is to undertake immediate actions to address climate change. Coral restoration programs and measures to combat local stressors causing coral bleaching should be the way forward.

                                                       Article by SANJIT RAJ