Daily Answer Writing
25 June 2021

 Q) What is the importance of corals in coastal ecosystem? What are the anthropogenic challenges that these ecosystems face today. (250 Words)

Source: <https://www.telegraphindia.com/india/save-coral-islands-from-disaster-say-scientists/cid/1819983>

GS 3: Environment

Approach Answer:

Introduction: Corals are Calcareous animals that live in stationary colonies called polyps with symbiotic relationship which gives them the characteristic brilliant shades. Due to extremely high level of productivity they are referred to as the “rainforests of the seas”. Coral reef ecosystems  provide livelihood to an estimated 30 million small-scale fishermen's and women's livelihoods depend, and food stock to around 500 million people.


Benefits of Coral for Coastal ecosystem: They protect shorelines from storms and provide food for millions of people. Losing them can have catastrophic consequences for local food, fisheries & livelihoods.

              • Habitat: Corals are home to over 1 million diverse aquatic species, including thousands of fish species.

              • Coastal Protection: Coral reefs reduce shoreline erosion by absorbing energy from the waves. They can protect coastal housing, agricultural land, and beaches.

              • Fisheries stock: Coral reef ecosystems are less than 0.1% of the ocean area but provide food and shelter to 25% of all marine species.

              • Nutrient recycling: Corals are the source of nitrogen and other essential nutrients for marine food chains, and assist in carbon and nitrogen fixing.

              • Purification of Sea water: Most corals and sponges are filter feeders, which means that they consume particulate matter suspended in the water column. This contributes to enhanced quality and clarity of our near shore waters. It also prevents harmful algal blooms.


Anthropogenic challenges

              • Pollution:

                Toxins are dumped directly into the ocean or carried by river systems from sources upstream.  For example many Sun Creams contains  oxybenzone which is harmful to corals.

                Sewage and runoff from farming cause an overgrowth of algae, which 'smothers' reefs by cutting off their sunlight.

                Oil spills

              • Climate Change

                Coral Bleaching: Due to temperature rise toxicity of algae increases. Some bleaching is now reported every summer from across the world.

                Ocean Acidification: Ocean is acidified due to their uptake of anthropogenic CO2 from the atmosphere. This is disastrous for all shelled organisms.

                Reduced growth rate: due to temperature stress.

                Lesser sunlight: due to algal on the surface water.

                Greater susceptibility to diseases such as white band disease and brown band disease.

              • Mining: Such as sand mining sea-floor dredging etc.

              • Intensive Fishing:

                Overfishing of herbivorous fish can lead to high levels of algal growth.

                Destructive Fishing Methods: Fishing with dynamite, cyanide, bottom trawling and Muro Ami (banging on the reef with sticks) can damage entire reefs and is unsustainable.

              • Recreational Activities:  Physical damage to the coral reefs can occur through contact from careless swimmers, divers, and poorly placed boat anchors.

              • Coastal Development: Due to dredging and land reclamation.

                Airports and buildings are often built on land reclaimed from the sea.


Conclusion: Very little of the world's reef area has been studied scientifically and those reefs that have been studied were measured only at a few dive sites. Thus there needs to be a two way effort in this regard one is to enhance expenditure in spending on exploration on projects like Coastal Zone Studies (CZS) conducted by ministry of environment.

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