Why are coral reefs at risk?

Coral reefs are one of the most important ecosystems on earth. Coral reefs occupy only 0.2% of the total ocean area, but it is said that a quarter of all marine life is related to coral reefs. About 4000 fish species and millions of other unknown organisms depend on coral reefs for their survival.
But what role do coral reefs play?
Coral reefs serve as an essential food source, providing key nutrients and proteins for one billion people worldwide, protecting coastlines from erosion and storm surges, and enhancing the tourism economy.
It also plays a fundamental role in sustaining marine ecosystems, as even marine organisms that do not directly eat coral depend on it to sustain their prey.
But what role do coral reefs play? Coral reefs serve as an essential food source, providing key nutrients and protein for one billion people worldwide, protecting coastlines from erosion, storm surges and enhancing the tourism economy. It also plays a fundamental role in sustaining marine ecosystems, as even marine organisms that do not directly eat coral depend on it to sustain their prey.

However, coral reefs are currently in dire danger. A recent study found that 50% of the world's coral reefs have already been destroyed, and another 40% could be lost over the next 30 years.

So why is this happening and how can we stop it?

Impact of global warming on coral reefs

One of the biggest causes of coral reef decline is coral bleaching due to global warming. Coral bleaching is when corals release brightly colored algae due to heat stress, turning them white. If bleaching continues for more than a few weeks, the coral will starve. When bleaching occurs, corals are effectively dead and unable to provide habitat for surrounding marine life.

The study found a link between heat exposure and bleaching, revealing that the most severely damaged areas were those that were most affected by heat exposure. . Of the 3,863 mini-reefs that make up the Great Barrier Reef, 29% were found to have lost more than two-thirds of their corals. Coral bleaching is likely to become more common as ocean temperatures warm, and scientists warn that many corals will not survive if temperatures rise by another 2 degrees Celsius.

Sea level rise due to global warming could have serious consequences for coral reefs as they rely on shallow water for survival. Coral reefs have built up layers of coral over many years to cope with natural sea level rise, but in recent years there have been concerns about the loss of coral reefs. However, researchers fear that the decline in coral reefs in recent years means that they will not be able to grow rapidly enough to keep up with projected sea-level rise.
This can affect the ability of reefs to reduce wave energy and regulate water circulation, making them more susceptible to wave destruction.
A recent study by researchers in the Atlantic and Indian Oceans measured the growth rates of 200 coral reefs and compared their growth rates with a 2.6°C increase in temperature. As a result, only 3-6% of the reefs surveyed in the Indian and Atlantic Oceans were able to compensate for projected sea level rise, while the remaining reefs saw depth rises of more than 0.5 m, causing waves to swell on the reefs. It became clear that the devastating impact on the region would get worse.

"The two hazards posed by climate change - rising ocean temperatures and increasing acidity - will, if they continue to rise at their current rates, coral reefs disappear within decades and become a global catastrophe.

- Dr. David Attenborough (natural historian and British broadcast writer)

Japan and coral reefs

According to a survey by the Ministry of the Environment, only 1.4% of Okinawa's largest coral reef, the Sekisei Lagoon, is currently in a healthy state. More than 350 types of coral live here, making it a popular diving spot in Okinawa. However, in 2016, about 90% of corals suffered damage due to coral bleaching, 70% of which were completely destroyed.

The 67.89-square-kilometer Budgie Lagoon has lost nearly 80% of its total coral abundance since the 1980s, due to rising water temperatures and the prevalence of coral-eating starfish. Once brimming with vibrant colors and abundant aquatic life, coral reefs are now pale.

However, coral bleaching is thought to be a serious problem due to water pollution and rising sea temperatures in recent years. According to the Japan Meteorological Agency, over the past 100 years, the sea surface temperature near Japan has risen by an average of 1.07°C, more than double the global average.

Coral bleaching is a global problem, as are many of the environmental problems affecting the world's oceans, such as the growing amount of plastic waste. Coral reefs have a staggering amount of biodiversity and are said to be home to one-fourth of the fish that live in the ocean. An estimated 1 billion people depend on coral reefs for food and fishing income.

How can you help?

If, like our plastic pollution guide, we are aware of the consequences of our actions, we have a chance to change our habits for the better and reduce our impact on our oceans.

Here are three things you can do to make a difference.

• Spread the current situation on social media – Share the current situation with more people on , twitter, Instagram, Facebook, etc.

• Be careful with your sunscreen - check the ingredients in your sunscreen to make sure it doesn't contain chemicals that are harmful to marine life. When diving, protect the coral by not touching it

• Donations and Volunteers – We have listed above the charities that are committed to protecting coral reefs. You can also help clean up local beaches and reefs. If you don't live near the coast, check how you protect your watershed.

References

Delbeek, J. Aquarium Sciences and Conservation , (2001) Earthjustice. Coral Reefs and the Unintended Impact of Tourism . Ezzat, L. Coral reef growth affected by sea level rise – Coral Guardian . Coral Guardian. (2018) Globalissues.org. Coral Reefs — Global Issues . (2013) Icriforum.org. Status of and Threat to Coral Reefs | International Coral Reef Initiative . Interamerican Association for Environmental Defense (AIDA). Coral Reefs and the Unintended Impacts of Tourism . (2016) Nationalgeographic.com. Can new science save dying coral reefs? . (2018) Nature.com. What risks do Tourists Pose to Coral Reefs? Are We Loving the Reefs to Death? | Saltwater Science | Learn Science at Scitable . (2013) The World Counts. Percent of coral reefs left – globally, right now . UN Environment. Building the world's first land-based coral farm . (2019)

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