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The Coral Crisis

Updated: Jan 16

Coral reefs are one of the oceans’ many spectacles, and probably their biggest, as corals are the largest biological, living structures on earth. These colorful and complex systems add a pop of color to the vast, dark ocean, but, unfortunately, coral reefs are rapidly losing their color and dying out. What happened to make coral reefs start dying so quickly when they’ve existed and thrived for over 400 million years?


Corals are living organic structures called anthozoans within the phylum Cnidaria. No, this isn’t the name for an alien species. Anthozoans are a class of marine invertebrates that includes stony coral, soft coral, anemones, and thousands of other species. Cnidaria is a phylum, or class within the animal kingdom, that contains species of animals typically found in marine environments and are made of medusae or polyps. Our corals are made of hundreds of thousands of polyps, or tiny, individual organisms.

Coral reefs live in tropical oceans and require a band of environmental conditions in order to thrive, including having specific water temperatures and the right amount of limestone for reef formation. The optimal water temperature for coral reefs is 23°C to 29°C, but some have even been found in seas that reach 40°C for periods of time. They also typically only form in saline water with plenty of access to sunlight. Individual corals themselves, however, live in waters of much lower temperatures around 14°C to 11°C.

Importance of Coral Reefs

Coral reefs, known as the forests of the oceans, are one of the most valuable ecosystems on earth. Thousands of sea creatures reside in coral reefs as their home, including around 4,000 species of fish and 800 species of hard corals, as well as various other species. Not only do they act like an apartment complex for marine life, but they also serve many of their residents full meals, such as the parrot fish that consume the algae growing on the corals.

This biodiversity leads scientists to believe that millions of undiscovered species can be found in the reefs. Drugs and remedies for cancer, arthritis, bacterial infections, viruses, and other diseases are being developed from coral reef animals and plants. Coral also acts as a barrier for storms and floods that come from the ocean and can potentially harm coastal communities.

Economically, coral reefs serve a great purpose to those in developing countries. Because so many types of fish live in the reefs, many fishermen rely on them. Tourists are also attracted to the marvel of coral reefs, and their money helps support these tropical countries that rely heavily on income from tourism.

As coral reefs die, thousands of species die with them, so we will lose potential medicinal remedies, places relying on the economic benefits of coral reefs will struggle, and storms will wreak havoc on coastal communities.

Death of Coral Reefs

The rapid decline of coral reefs is caused by a myriad of reasons, including climate change, overfishing and harmful fishing practices, live coral collection, and pollution.

As previously stated, coral reefs need specific temperature requirements to survive. Rising ocean temperatures put stress on coral reefs, causing them to release the symbiotic algae zooxanthellae. Since this is their primary food source, the corals grow weaker and become even more susceptible to environmental stressors. This leads to coral bleaching, which is when corals turn white and pale as a result of their weakening, eventually leading to their deaths. Climate change can also lead to increased natural disasters that can destroy coral reefs.

Certain fishing practices, like deep water trawling, can cause damage to coral reefs. Deep water trawling is when fishermen drag a fishing net on the ocean floor with weights on the ends of them to startle fish out of hiding. The weights can destroy the corals, while the nets get tangled or caught in them. Anchors carelessly dropped from fishing boats can also cause damage to the corals. Another harmful fishing method is using explosives to scare fish out of hiding. The explosives, as one might expect, destroy the coral in the process. Cyanide fishing can also kill the polyps that make up the corals and degrade the habitat.

People also carelessly collect live corals directly from coral reefs for aquariums and jewelry trades. Divers and tourists can trample and destroy corals, or simply pluck them from their natural habitat.

Pollutants like sediments, oils, and chemicals can also cause harm to the coral reefs. When pollutants enter the water, they can corrupt the water and increase the growth of organisms such as algae that smother the corals. If oil is spilled during coral spawning, then the sperm may be damaged as they float near the surface. Sediment in the water can also smother the corals and prevent them from feeding.

A large percentage of the world’s coral reefs have already died off. Over the last 50 years, 30% of the world’s coral reefs have died, and it’s predicted that by 2050, 90% of the world’s corals will die. There are very few pure coral reefs left, in which no corals or sections of the reef have died. Even the Great Barrier Reef is rapidly vanishing. The ARC Center for Excellence funded a study that found that around half of the Great Barrier Reef’s corals have disappeared entirely. Within the next century, the Great Barrier Reef could vanish entirely.

How You Can Help

One of the easiest ways to help save our coral reefs is to reduce your carbon footprint. Conservation of water can also help, since all water you use gets sent into the ocean. Contaminants in your water will eventually wind up with the reefs, adding to their destruction. If you ever go scuba diving, don’t take the corals as a souvenir. There are souvenir shops for a reason. Refrain from touching the corals and be very gentle with them.

Supporting sustainable fishing practices by making informed choices about the fish you consume and purchase can also help. The biggest thing is staying informed and informing others about the coral reef crisis, whether that includes posting about it on social media or bringing it up in casual conversation.



Coral reefs are organic structures in the oceans, classified as anthozoans of the phylum Cnidaria. They require specific water temperatures in order to thrive. They are part of some of the most valuable ecosystems on the planet, as they are home to many marine organisms, such as fish and hard corals. They serve many benefits, such as medicinal purposes, protection from storms and floods for coastal communities, and bringing in tourist income for tropical destinations.

Recently, coral reefs have been declining due to human impact. Climate change has changed the temperatures of the oceans, causing stress upon coral reefs that makes the corals turn pale, weaken, and die. Harmful fishing practices, including deep water trawling, explosive fishing, and cyanide fishing also hurt the corals. Divers, often tourists, don’t treat corals with care, and can harm them by trampling them or by collecting them. Pollution has also caused corals to be smothered and unable to feed. A large percentage of the world’s corals has died off, and will continue to die off in the coming years.

Ways to combat this tragic fate include reducing your carbon footprint and conserving water. It’s also important to be informed, both about sustainable fishing practices and about the coral reef crisis itself.

Stay updated and active by following the Environmental Defense Initiative on Medium and our social media platforms!

Author: Ina Sabarre

Editor: Charlotte Wang


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