8 Things Everyone Needs to Know About Dying Coral Reefs

If you’ve ever seen a picture of a coral reef or an online video of these deep-sea rock formations, you’ll undoubtedly agree that they are breathtakingly beautiful. Coral reef facts are also intriguing pieces of information that can grant us some insight into the tranquil underwater world in which these vibrant and colorful ecosystems thrive. Unfortunately, with the industrial revolution depleting the earth of its natural resources and increasing the levels of pollution in water bodies, these reefs are dying out.

Despite being aware of trivia and other coral reef facts, a lot of people continue to remain unaware of this imminent and very real threat to coral reefs. Read on to learn all about what coral reefs are, why they’re dying, and some other interesting coral reef facts.

What Is a Coral Reef?

One of the first things you’ll learn when you look up coral reef facts is the definition of what a coral reef is. In layman terms, a coral is a kind of marine invertebrate animal, and a coral reef is a ridge of rocks under the sea, formed by the continuous growth and deposit of coral. Among other interesting coral reef facts is the detail that these corals that go on to make the massive coral reefs are hermatypic or hard corals. They’re considered so because they extract calcium carbonate from the water in the sea and use it to develop a hard, outer skeleton to guard their soft, sac-like bodies within.

How Are Coral Reefs Formed?

A coral reef is formed when coral larvae affix themselves to rocks or the soil near the seacoast. The land forming the coast could be a continent or an island. These larvae then transform into polyps, giving off the calcium carbonate from their exoskeleton. The microscopic algae in the waters of the sea help these polyps grow, and when they multiply this way, they produce more deposits of calcium carbonate.

These deposits settle on to the rock in layers, and newer coral larvae attach themselves to these layers, adding to the already growing deposits of calcium carbonate. As decades pass by and turn into centuries, these deposits develop into the massive and diverse rock formations that we now refer to as coral reefs.

What Are the Different Kinds of Coral Reef Formations?

One of the many intriguing coral reef facts is the variety of formations that coral reefs take on.

Typically, there are three primary kinds, as explained below.

  • Fringing reefs—These are the coral reefs that are formed near the coast, along with the shoreline and surrounding the border of islands.
  • Barrier reefs – These reefs are formed as the fringing reefs grow and combine together, creating reefs that run long distances along the coast or form a ring around an island.
  • Coral Atoll—These are usually massive coral formations that are roughly circular and surround central lagoons that are often large and deep.
coral reefs

Coral Bleaching—The Mechanism of Cause and Effect

Coral reefs contain symbiotic algae that help corals grow on them. These algae, also known as zooxanthellae, are what give coral reefs their brilliant array of colors, ranging from blue, green, golden brown, or even red and pink. The polyps themselves have exoskeletons that are just plain white. But its millions of these algae that live inside their tissues that produce these vibrant hues.

Unfortunately, due to several factors like pollution, elevated sea temperatures, and climatic changes, these colorful coral reefs are being affected adversely by a phenomenon called coral bleaching.

What Is Coral Bleaching?

Coral bleaching is exactly as it sounds. It’s a term that refers to the whitening of otherwise colorful corals, due to the loss of the millions of algae that gives these coral reefs their bright and distinct hues. Bleaching not only results in loss of color but also affects the wide variety of marine life forms that have made coral reefs their home. If you’re wondering what causes coral bleaching, then continue reading as the primary causes are listed below.

The Causes of Coral Bleaching

Some of the many causes of coral bleaching include:

  • Changes in water temperature, particularly due to global warming
  • Silt runoffs that cause increased sedimentation around coral reefs
  • Drastically low tides that cause increased exposure to sunlight
  • Human activities like cyanide fishing and the use of herbicides
  • Nonbiodegradable pollutants found in sunscreen that wash off the skin when people take dips in the sea
  • Oil and chemical spills that pollute the ocean
  • Acidification of ocean water caused by high levels of carbon dioxide in the air (which is, in turn, a result of air pollution)

The Effects on Coral Reefs

As a result of the causes mentioned above, a number of disastrous effects come into play. Some of these negative effects are listed below.

  • Loss of colors in the coral reef, eroding it and causing it to turn white
  • Reduced reproductive capacity and elevated mortality rates in the coral reefs
  • Adverse impact on the species of fish and other sea creatures that inhabit these coral reefs
  • The possibility of extinction of several species of marine life like sea turtles, whale sharks, and butterfly fish
  • Increased damage to coastlines from tropical storms because of erosion of coral reefs, which otherwise protect the coast from strong currents

Why They Are Dying—8 Coral Reef Facts Everyone Needs to Know

Despite the strongly unfavorable effects that coral reef bleaching can have on the oceanic ecosystem in particular and the environment in general, a large segment of the human population is unaware of the problem. Here are some coral reef facts that can give you a better idea of what goes on in these beautiful natural rock formations, and of the unfortunate state they are in at present.

Fast Facts About Coral Reefs

  • Coral reefs don’t always turn white as a result of bleaching. Sometimes, they can take on a shade of pastel blue, pink, or yellow. Some coral reefs also turn pale due to bleaching, which makes their tissue nearly transparent and gives them a skeletal form that’s far removed from their otherwise healthy and vibrant appearance.
  • Corals are extremely sensitive to stress. The loss of algae is a response to the stress that affects coral reefs on account of external factors like change in the water temperature, fluctuations in the acid-alkaline balance in the ocean water, and increased exposure to sunlight. All of these cause corals to shed the algae.
  • The algae themselves are extremely sensitive to changes in the oceanic environment around them. A change as little as a rise of one degree Celsius in the temperature of the sea water can drastically affect the process of photosynthesis in the algae. If these changes last for prolonged periods, the algae begin to produce toxins.
  • When algae become toxic, the corals are forced to expel them as an act of self-defense. This may be beneficial in the short run. In the long run, however, the loss of algae affects corals because, without algae, the corals have no food on which to feed. So, unless the stressors are removed, the corals can die of starvation or disease.
  • Some corals are more sensitive to bleaching than others. Slow-growing corals react much less to environmental changes than fast-growing corals like Pocilloporids, which are more susceptible to rapid bleaching. Some corals even have protective fluorescent pigments that convert severe UV rays from the sun into rays with lower energy wavelengths.
  • Pollution does not only cause coral bleaching. It can also have other adverse effects on corals like the formation of coral diseases. The difference in appearance is that while bleached corals are almost entirely stripped of their colors, turning them white, diseased corals sport white bands or strips on their surface.
  • A rise in sea levels can also adversely impact coral reef systems. A coral reef can only survive and thrive at a maximum depth of about 150 feet. If they go any deeper than that, the levels of sunlight they receive drop drastically. This means that the algae on the corals do not receive adequate sunlight to carry out photosynthesis, making the survival of the corals increasingly difficult.
  • If the stressor that caused the bleaching of a coral reef is removed or eliminated, it can take the reef an average of ten years to recover. This is only true provided no new stressors are added to the environment around the coral reef during the recovery period. A coral reef's likelihood of recovery lessens as incidents of bleaching increase.
coral reefs


Now that you’ve learned some startling coral reef facts, you’ll find it easier to appreciate what a delicate balance it is that exists in the coral reef ecosystem. It’s no wonder that at the rate at which climactic changes are now occurring, coral reefs are finding it hard to cope with the levels of environmental stress. If things continue to progress in the way they are at present, we may, someday in the not-so-far future, witness the extinction of these beautiful underwater rock formations that are already fast dying out.

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Tyler Szeklia

I am a web developer who is working as a freelancer. I am living in Canada with my young son and an old cat named Oscar.

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