Why coral die-off is a problem | Knowledge & Environment | DW

Coral reefs are made up of huge limestone structures built by thousands of tiny coral animals called polyps. With their complex biodiversity they are irreplaceable for the oceans. They are found in more than 100 countries – and not only in the tropics, by the way, because corals also thrive in colder sea regions.

But the reefs are anything but healthy. Our planet has already lost about half of its shallow-water corals in the last three decades. If coral death continues at this rate, up to 90 percent of all corals will be gone in less than 30 years. And that would be far more dramatic to the world than just a few fewer coral videos on social media.

Coral reefs very important for flood protection worldwide

Quite practically, reefs offer excellent Protection from floods. Around 200 million people worldwide depend on such coral reefs because they live in coastal regions that are threatened by storm surges and waves, such as in the USA. The reefs act like low-lying breakwaters and absorb 97 percent of the wave energy. This will significantly reduce coastal flooding and erosion.

According to the United States Geological Survey, reefs help prevent $1.8 billion in damage every year in areas like Florida, Hawaii and Puerto Rico. If the reefs lose a meter in height, there is a risk of property and economic damage amounting to five billion dollars.

With coastal flooding projected to increase further this century due to climate change, reefs will become even more important. Maybe you’re thinking: “Ok, but that’s only relevant for people who live by the sea”. But that’s a lot of people. And besides, corals are not only good for coastal protection.

Why coral reef biodiversity is so important

Coral reefs cover less than 0.5 percent of the earth’s surface, but they are home to about 25 percent of all marine animal and plant species worldwide. They are something like the rainforests of the seas.

And when it comes to biodiversity, more is better. Because the biodiversity ensures the resilience of the planet, represents a vast resource for potential scientific discoveries and is the result of millions of years of evolution. Biodiversity is the basis for a healthy planet and for our social well-being.

Almost everything we know about coral reefs relates to the offshore reefs. But most reefs are remote, species-rich hotspots in otherwise barren ocean basins, where they serve as a source of food, resting places, and even signposts for migratory species. Many of them have hardly been explored and are endangered.

The priceless loss of this legacy To ignore and allow these reefs to be destroyed is like burning the vast library of ancient Alexandria. We would never really know how much we lost. We will never be able to find out what knowledge was contained in it.

Many medicines come from coral reefs

A large number of medicines are derived from natural sources. So far, most of them come from organisms that can be found on land.

Marine organisms offer untapped potential for new medicines

However, with 80 percent of life on our planet taking place underwater, researchers are increasingly looking to marine organisms to find novel chemicals and enzymes for the development of new drugs. It has been estimated that the chances of discovering a new drug in the sea, and especially in coral reefs, are a hundred times more likely than on land.

The cancer drug Ara-C, which is on the World Health Organization’s List of Essential Medicines, is found in sea sponges on a Caribbean coral reef. Some Anaspidea species, also known as sea hares, also have medicinal potential. Some of these sea slugs look a bit like Mexican cheese tortillas. But what they lack in good looks, they make up for in inner values: for example, in the form of an active ingredient that is being tested as a remedy against breast and liver cancer, tumors and leukemia.

Another promising compound, eleutherobin, has been shown to slow the growth of cancer cells in the laboratory and is found in a common species of soft coral. Scientists have been able to use their genetic code to figure out how to make the chemical—perhaps soon in large quantities.

Another success story from nature’s medicine cabinet is trabectedin, which is used in chemotherapy. It’s found in sea squirts (Ecteinascidia turbinata), a species that looks a bit like someone planted bits of a garden hose underwater.

Without coral reefs we could hardly eat fish

Humans eat about 150 million tons of fish and seafood annually, and these animals have to reproduce somewhere. Coral reefs offer ideal conditions for this and serve as a huge nursery for commercially very important fish such as grouper and snapper, and also for invertebrates such as lobster.

According to studies, the world’s coral reef fisheries are worth $6.8 billion a year. About a billion people get their food or income directly from the reefs. In countries like the Maldives, they provide 77 percent of animal protein. If managed well, the reefs can continue to provide this important food source.

What if we lose more coral reefs?

There are efforts to restore reefs by growing new corals, but climate change could derail all of these attempts

If more coral reefs are destroyed, there is a risk of food shortages, especially in combination with crop failures due to climate change. A study of reef damage in Kenya found a sharp drop in key fish catches after a combination of factors warmed the ocean by one to two degrees Celsius in 1998.

Moreover, without the services of the reefs, it could come to mass migrations, as people from the coastal regions will try to escape famine and flooding and will have to find new places to live and food.

What Can We Do About Coral Dying?

There are many ways to protect coral reefs: local restoration of the reefs by the planting new corals, the establishment of marine protected areas or by using less fertilizer, pesticides or other sewage into the sea – one of the most important measures of all.

But all these efforts could be in vain if humanity does not get climate change under control. Then he poses the greatest threat for the future of coral reefs. In the long term, only a reduction in global greenhouse gas emissions offers a real chance of survival for coral reefs.

Adaptation from English: Jeannette Cwienk