What are coral reefs?
A coral reef is an underwater ecosystem composed of colonies of coral polyps that extract calcium carbonate from seawater to create a stony exoskeleton that protects their soft bodies. Corals attach their bodies to the bottom of the ocean like plants do but they are in fact, animals. Corals have tiny, tentacle-like arms that they use to capture the food from the water. They contain algae (plant-like organisms) that use the coral’s metabolic waste for photosynthesis and make their own food while the corals benefit in turn from the algae to grow and build up the reef. This mutual exchange endured for millions of years and it is the reason why the coral reefs are the largest structures in the world. Coral reefs first appeared 485 million years ago and most of the ones found today are between 5000 and 10000 years old.
They are usually found in the shallow waters in the Indo-Pacific area where they account for 91.9% of them while the coral reefs in the Atlantic and Caribbean regions account for 7.6% of the total. (1) (2) (3) (4) (5)
Why are coral reefs important?
Coral reefs cover less than 0.1% of the ocean but they sustain the life of 25% of all marine species. Over a million species live on, in, and around the reefs. Corals have been providing food and safe habitat for these species for more than 50 million years. They also act as water filters and protect it from becoming murky. The remaining species in the ocean depend on fish to feed themselves. No fish, no dolphins, no whales etc. No whales no phytoplankton (whales fertilize the surface area of the water providing vital nutrients for phytoplankton to grow and thrive). No phytoplankton, no small fish but most importantly, no phytoplankton, no oxygen. Up to 80% of the oxygen produced on this planet comes from phytoplankton in the oceans. In order for us to continue to breathe, we need to have a healthy living ocean. (6) (7)
Over 39% of the world population lives within 100 km of the coast and many people in these areas depend on reefs. Half a billion people directly depend on reefs for food, income, and coastal protection. One estimate says that coral reefs bring an annual income of 375billion USD each year mainly from tourism and fishing.
Moreover, the strong healthy coral reefs serve as natural barriers that protect the local cities, coasts, and beaches from the ocean waves, storms (like hurricanes, typhoons, and even tsunamis), floods, and erosion. They absorb up to 97% of a wave’s energy. (8) Coral reefs mean oxygen, a healthy ocean, fish, and safety.
The threats
Overfishing, ocean acidification, and pollution are pushing coral reefs into oblivion. Each of those forces alone is fully capable of causing the global collapse of coral reefs; together, they assure it. (Roger Bradbury, an ecologist at the Australian National University in Canberra – article in New York Times (9)
Climate change and global warming represent a direct threat to the coral reefs ecosystem. When the temperature increases, the polyps expel the algae which are vital for reefs. They lose their color (“bleached appearance”), a stress which leads to their death. The coral bleaching in 1998 linked to the El Niño event destroyed 16% of the coral reefs throughout the world and was one of the worst on record. But the 2014-2017 El Niño was the most damaging to the corals and harmed over 70% of the coral reefs. Half of the coral reefs have already been destroyed, and the other 40% are estimated to be gone within the next 30 years. (10) (11)
Water pollution is another serious threat. Runoff and effluent discharge of agricultural pesticides and fertilizers, industrial waste, sewage discharge, and sediment from eroded landscape lead to a slow and gradual decline of reef health. A 2019 research shows that nitrogen loading from the Florida Keys and the greater Everglades ecosystem caused by humans, rather than warming temperatures, is the primary driver of coral reef degradation. (12) Nitrogen is required for phytoplankton to grow but too much nitrogen leads to its stimulated growth which prevents the coral reef from exposure to light and may create a proliferation of seaweeds that outgrow the slow-growing corals adapted to low nutrient concentrations typical of tropical seas.
Overfishing and destructive fishing practices brought severe damage to the fish habitat and the whole ecosystem. With fewer fish on the reefs, many fishermen have resorted to more efficient yet highly damaging methods, such as blast fishing (explosives and overfishing with trawlers can destroy a thousand-year-old coral reef in a matter of minutes) and cyanide fishing (spraying cyanide in the reef cavities to stun the fish facilitating their capture).
Tourism impact on the coral reefs has also been disastrous. Sedimentation, loss of habitat, solid waste, sewage, unregulated construction, irresponsible operation of tourist-related facilities, and even direct damage by careless tourists.
If we continue like this, 60% of the coral reefs will be highly or critically threatened by 2030 and 98% will be exposed to potentially fatal conditions each year. Some studies show that the coral reefs could be mostly wiped out by 2050. And then what?
What can be done?
If we want to breathe we have to let this planet breathe first. The end is literally knocking at our doors. Can we still stop global warming? Can we switch to a sustainable living? We can if we do it together. The earth doesn’t need us. We need the earth.