For coral reefs, things are not looking too good

Why does it matter if they are being bleached or cooked in warming seas?

Coral reefs are not just good for holidays. | Photo Credit: Dirschelrl Reinhard/Prisma/picture alliance

Coral reefs are essentially just big limestone structures built by thousands of tiny coral creatures called polyps. They are found in more than 100 countries, and just like pina coladas, they belong in tropical areas. But they are not looking too healthy.

Increased ocean temperature caused by climate change is the main cause of coral bleaching events. That is when reefs expel the symbiotic algae responsible for their colour. If that happens over longer periods, the corals can eventually die.

The planet has already lost about half of its shallow water corals in in the past three decades. And at the current rate, up to 90 per cent of them will disappear by the middle of the century. That really is a big deal, and not just because it would mean fewer BeReal posts from the Great Barrier Reef.

What are reefs good for?

Let us start with flood protection. Some 200 million people around the world depend on reefs to protect their coastal communities from storm surges and waves. Many of those people live in the US. Coral reefs act like low-crested breakwaters and absorb 97 per cent of wave energy. This substantially reduces coastal flooding and erosion.

According to the United States Geological Survey, reefs help avert $1.8 billion in damage each year in areas like Florida, Hawaii, and Puerto Rico. And if those reefs lose just one metre in height, $5 billion in property and economic damage is at risk.

With coastal flooding predicted to worsen this century, reefs will play an even more important role.

Maybe you are thinking, “But that’s only relevant for people who live by the sea.” That’s already a lot of people. And besides, coastal defence is not the only thing reefs do for us.

What else do reefs do then?

Coral reefs cover less than 0.5 per cent of the earth’s surface, but they are home to about 25 per cent of all marine species. Kind of like the rainforests of the sea. But without the snakes. Well, there might be some snakes.

With biodiversity, more is better. It provides planetary resilience, a vast resource of potential scientific discoveries, and is the result of millions of years of evolution. Biodiversity underpins a healthy planet and social well-being.

Huh, it’s not like corals reefs pay our wages?

Almost everything we know about coral reefs is based on those close to our shores, but most of them are distant, biodiverse hotspots in otherwise barren ocean basins, where they act as food bowls, rest stops, and even navigation waypoints for critters on the go. This diversity is a treasure of incalculable value.

Ignoring the intangible loss of heritage, allowing the destruction of these reefs is like burning the Great Library of Alexandria. We will never know what we’ve lost.

Why does that matter?

A huge number of modern medicine’s drugs are derived from natural sources. And so far, most of those have come from land organisms.

But given 80 per cent of life is under water, researchers are increasingly looking to marine organisms to satisfy the need for novel chemicals and enzymes to build the pharmaceuticals of tomorrow. Some estimates say the prospects of discovering a new drug in the sea, particularly in coral reefs, is hundreds of times more likely than finding one on land.

The anticancer agent Ara-C, included on the World Health Organization’s List of Essential Medicines, is found in sea sponges on a Caribbean reef.

Ever heard of a sea hare? It’s a very generous name for some gastropods that look more like dodgy quesadillas. But what they lack in good looks, they make up for with the presence of Dolastatin 10, which is being tested as a treatment for breast and liver cancers, tumors, and leukemia.

One promising molecule, eleutherobin, that is believed to slow cancer cell growth is found in a common species of soft coral. Scientists have been able to use its genetic code to figure out how they might soon be able to manufacture the chemical in large quantities. Another success story from nature’s medicine cabinet is trabectedin, found in the sea squirt Ecteinascidia turbinata, and used in chemotherapy.

Anything else?

Maybe you’re hungry. Humans eat about 150 million tons of seafood a yea,r and these fish have to breed somewhere. Coral reefs provide shelter and function as nursery grounds for some pretty commercially important fish, like grouper and snapper, as well as invertebrates like the lobster.

Some studies put the value of coral reef fisheries at $6.8 billion a year globally. About one billion people source their food or income directly from reefs. In countries like the Maldives, it provides people with 77% of their dietary animal protein. If managed well, reefs can continue providing this important source of food.

And if they’re not managed well?

Potential food shortages could be the consequence. Especially when combined with failing crops from climate change. A study of reef damage in Kenya revealed drastic declines in key fish catches after a combination of factors in 1998 warmed the ocean by between 1-2 degrees Celcius.

That’s not to mention the possibility of increased mass migration, as people try and avoid famine and flooding.

So what do we do?

Take a guess.

There is a myriad of ways to protect reefs—local restoration efforts by transplanting coral, the establishment of marine protection areas that work like national parks, and stopping run-off from agriculture and effluence. But these efforts might all be in vain if humanity does not get a hold on climate change, which presents the biggest singular threat to the future of coral reefs.

In the long term, reducing emissions will give coral reefs their best shot at survival.