The importance of Coral Reefs (and the threats they face)

What are coral reefs?

A surprising fact for many people is that coral reefs are actually animals. Coral reefs are made up of small invertebrates called ‘polyps’ ( which they are related to jellyfish) and together they form large colonies and act as an organism. It has taken thousands and millions of years for these colonies to grow and reach their current size. They use calcium carbonate to build their exoskeleton and grow bigger and bigger.

Corals are actually translucent. It’s the algae that give them their famous bright colors. They have a symbiotic relationship. This means that both the corals and the algae are benefiting from this relationship. The algae which live on them are photosynthesizing plants. Corals can get nutrients from the byproducts that these algae produce. In addition to this, they can use their tentacles to get zooplankton and even small fish.

Similarly, corals produce nutrients that the algae then take in and they also provide them with shelter.

Coral reefs can be found around the world. Most of them being between the Tropic of Cancer and Tropic of Capricorn. In general, they are located in areas with warm water currents. The biggest coral reef is found in Australia; the famous Great Barrier Reef

Why are they important?

No one can deny that coral reefs are important. They do a lot, not only for us but for the whole planet. But what exactly do they do?

Protects coastlines

Coral reefs protect us from flooding, tsunamis, and more by reducing the flow of water and consequently, minimizing the impact and damage done to coastlines and the communities that live there. Furthermore, they protect mangroves and reduce erosion.


These ecosystems are very biodiverse. Coral reefs cover a very small percentage of the earth’s ocean floor but they are home to around 25% of all marine life. Millions of different species live there and have adapted to live there. This means if they were destroyed we would lose all that biodiversity since most of the marine life wouldn’t be able to survive anywhere else.

Coral reefs are also crucial for the young. It’s an important breeding ground and it’s where young animals are found (where there’s protection) before making leaving for the open waters.

Provide Food

Especially in developing countries, people rely on fish for protein. Corals that are managed sustainably can be a source for a large amount of fish. Some even sell what they catch to earn money. Hence, coral destruction is causing major difficulties in some countries as they can’t find enough food to eat.

Filter the water

They filter particles out of the water and increase water quality. That’s why the water is always so clear around coral reefs.


It attracts people to the area bringing the economic wealth. They also provide activities for tourists such as snorkeling. Some countries depend heavily on tourism so, without them, some economies could collapse.


Human activity such as pollution and global warming is threatening these biodiverse ecosystems. Coral reefs date back to over 400 million years ago but we have already destroyed over 50% of them in only a few decades.

Ocean Acidification

CaCO3 + CO2 + H2O -> 2HCO3 + Ca2+

Increased carbon dioxide levels are causing the exoskeleton of these corals to break down. This produces bicarbonate which is acidic. Ocean acidification affects marine life because they are not adapted to it. Their environment is changing too rapidly.

The species that are most threatened by ocean acidification are shellfish and corals. As the reaction above shows, calcium carbonate breaks down in the presence of carbon dioxide. Hence, less calcium carbonate is present in the ocean. Coral reefs require CaCO3 (calcium carbonate) to form their exoskeleton. Without it, they can’t grow.

Warming Waters

Coral bleaching happens as a result of warming waters. In these temperatures, they get stressed and release the algae that have been living on them. They get stressed due to the fact that the algae are doing more harm to the corals at these temperatures and no longer have that symbiotic relationship.

Coral bleaching reveals their true white skeleton. Corals then need to find other algae that can provide them with nutrients. This does not always happen and the corals die; effectively destroying the entire ecosystem because other marine life cannot live on this dead habitat.


Mining, farming, and other human activity is adding more sediment particles to the ocean floor. These block sunlight and therefore, algae and other plants can’t photosynthesize. No ecosystem can self-sustain itself without sunlight.


Overfishing is a global problem that is affecting countries and communities around the world. Not all fishermen carry out sustainable practices. Catching too many fish in a short period of time disrupts the food web in many ways.

Fishermen sometimes even use cyanide and other similar techniques to kills as many fish as they can. These practices not only kill a variety of species (many of which they don’t even want) but they destroy the seafloor including corals.


This includes rubbish, sewage, oil, plastics, and agricultural chemicals. Each type of pollution has different effects on this ecosystem. Some chemicals poison the corals, others block sunlight and some can even change the acidity of the water. Most things, if not everything, that we are dumping in the ocean is toxic to corals and to every other organism.

We need to realize that the ocean is not a dumpster. It’s not a magic portal that makes things disappear.


Even though coral reefs are good for tourism and the economy, there are problems with it. It’s true that it gives people the chance to appreciate how beautiful the earth is but careless tourism is becoming more of a threat to them.

Tourists often bring with them pollution which disrupts the ecosystem, but the bigger problem is when people go snorkeling and start touching them, collecting them and boats drop anchors on them.

Tourists need to take greater care when visiting them. They are only there to be admired.


We can’t afford to lose our coral reefs, which is what is predicted to happen if we continue at this rate. It took millions of years for them to become the extraordinary ecosystem they are now and it would take a lot of effort and time to help them restore them.

It’s just easier and cheaper to just stop these destructive practices now. It would cost more to restore the entire earth ( if it’s even possible) than to just reduce carbon emissions, pollution, etc.

We as a human race do not do well with long-term goals. We only think about current problems. But we must make an exception and think about the future now. Because if the time comes where we have destroyed everything single thing on the planet, there will be no fixing it. The earth is a complex system and we might be the most intelligent species, but we too have limits.

That’s why we need to work hard to protect what’s left of it.

Originally published at on August 11, 2020.



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