Corals - The Life Line of Marine Ecosystems

What are Corals

Corals are marine inhabiting invertebrate sea animals. They live in colonies of many identical individual polyps. Corals species build reefs in tropical oceans and secrete calcium carbonate to form a hard skeleton. They form some of the most biologically diverse marine ecosystem in the planet that houses over 4,000 species of fish, molluscs, crustaceans, and numerous other animals. These reefs also act as a barrier for coasts from currents and waves. 

Corals contribute to the physical structure of the coral reefs that develop in tropical and subtropical waters, such as the Great Barrier Reef off the coast in Australia. The best reefs are associated with the Barrier-type reefs located offshore in the northwestern, southeastern and the eastern waters. The Gulf of Mannar off the Tamil Nadu coast is an ecologically rich coral reef. Fringing reefs are abundant in the Andaman and Nicobar Islands, Myanmar, Sri Lanka, west coasts of Thailand and Malaysia and northwest Sumatra of Indonesia. Coral species in other locations in the Indian region include Gulf of Kutch and Lakshadweep.

Benefits

Corals are extracted for lime industry, to capture fisheries and harvest exotic reef resources for export and tourism related activities. Coral reefs also exhibit medicinal properties. They are used to treat cancer and AIDS. Due to their hard exterior they are used as a source of building material in some parts of the world. Corals are of many colours and are used in jewellery making. Their aesthetic appeal draws thousands of tourists all over the world. Increased human activities has degrade the quality of the reefs, particularly the nearshore regions.The multi benefits of corals has increased its demand all over the world.

Threats

Coral reefs are hyper-sensitive to climate. Increase in the temperature due to green house gas emissions lead to sea temperature rise which affects the corals. Water temperature changes of more than 1–2 °C or salinity changes have the potential to completely destroy few species of corals. When the sea surface temperature rises, corals turn white which is called bleaching. When bleaching is prolonged under extreme conditions they lose their life. They also require optimum chemical conditions in the sea to thrive. Due to thier diverse uses they are mined heavily. Urban runoffs, sewage waters that are directly discharged into the sea and pollution have destroyed the marine ecosystems. Over fishing or destructive fishing methods, over mining of corals, sedimentation, digging of canals and access into islands and bays are threats to coral ecosystems.

The Future

We have lost 16% of the world's reefs to climate change in the last century. Around 10% of the reefs are dead already. More than half of the world's reefs are at risk due to anthropogenic activities. The impact is worser in regions of Southeast Asia. If this state continues, in ten years time half of the coral reefs will be lost. The years 2016 and 2017 experienced consecutive mass bleaching of corals. Coral reefs in many locations suffered severe loss. 

While corals are gradually recovering, nations ought to protect them through environmental laws. Coral aquaculture or coral gardening, is the cultivation of corals for coral reef restoration or industrial uses. Aquaculture continues to remain as a potentially effective tool for restoring coral reefs. The hatchery technique involve growing fragments known as "seeds" in nurseries and then replanting them on the reef. This way the probability of corals surviving extreme conditions during its natal period is bypassed.