Learn: Coral Reefs
Called the “rainforests of the sea,” coral reefs occupy less than 1% of the ocean floor but support 25% of all marine life.
Overview: What are Coral Reefs, Exactly?
A coral reef is a diverse underwater ecosystem formed by colonies of coral polyps. Coral reefs are found in shallow, warmer waters where surface temperatures are between 68 to 97 degrees Fahrenheit.
Coral itself is a marine invertebrate animal. It is typically made up of tiny polyps that secrete calcium carbonate (limestone) skeletons, which form the hard structure of coral reefs.
Corals have a symbiotic relationship with microscopic algae called zooxanthellae, which live within their tissues and provide them with food through photosynthesis. This relationship is crucial for the survival and growth of corals. There are over 6,000 known species of coral, each with its unique shape, color, and growth pattern.
Quick Facts About Coral Reefs
Why are Coral Reefs Important?
Coral reefs are vital to humans and marine life alike. Here are just a few of the reasons why coral reefs are vitally important:
Habitat — As corals grow, they build reefs. The nooks and crannies of reefs provide habitat for nurseries and allow fish to hide from predators. Without the habitat that corals provide, many fish and other marine life wouldn’t be able to live. This would cause a cascade of effects through the entire ocean food chain.
Tourism & Recreation — It’s estimated that coral reefs generate $2.7 Trillion annually in goods and services. Coastal community economies are often highly dependent on the attraction that reefs create. The Great Barrier Reef, for example, attracts roughly 6.95 million visitors per year. Snorkeling and scuba diving, for instance, become far less interesting with all the life that reefs help to support.
Fishing — Both the commercial and recreational fishing industries depend greatly on the health of reefs. As mentioned before, coral reefs support 25% of all marine life, of that, there are some 4,000 species of fish. Without coral reefs, fish populations would be decimated.
Medicine — While many have called rainforests “Nature’s Medicine Cabinet,” estimates suggest there are 300 – 400 times more medicinal compounds in reefs than rainforests.
Flood Defense — Coral reefs reduce wave energy by 97%. This greatly affects the level of coastal erosion over time and as well, the impacts of storm surges on coastal communities during severe weather events.
Threats to Coral Reefs
Total coral reef populations have been dropping dramatically. As explained below, we’ve lost nearly half of our reefs already since 1950.
The process of coral reefs “dying” begins with what’s called coral bleaching (explained below), however, here is what has led to more coral bleaching events and stress on corals taking place:
Rising Ocean Temperatures — As a result of climate change, ocean temperatures have risen on average 1.3 degrees Fahrenheit since the late 19th century. Warmer temperatures stress corals resulting in bleaching events (more below).
Ocean Acidification — The ocean absorbs approximately ⅓ of the atmosphere’s excess carbon dioxide. This makes our oceans more acidic, affecting the habitability for many marine organisms, not just reefs. However, a more acidic ocean slows the rate at which coral can grow, or produce their limestone skeletons.
Overfishing / Unsustainable Fishing — The health of an ecosystem is not necessarily determined by the health of just one individual species but by the interactions between many. When certain fish populations are overfished, other algae, that compete with coral for space then lack a predator. Losing important predator-prey relationships in any ecosystem can dramatically affect the overall health of an ecosystem.
Bad Coastal Development — Bad coastal development can cause excess erosion and sediment runoff which can bury corals in sand. If corals don’t get enough sun they can bleach.
Poor Personal Practices — Toxic chemicals in sunscreens can stress coral reefs and affect the water quality. Scuba divers and snorkelers can kick coral and break it.
Why are Coral Reefs Dying?
The unfortunate truth is that half of coral reefs are already dead. To understand why coral reefs are dying, it’s worth understanding coral bleaching first.
Coral Bleaching — Coral bleaching often implies death for the coral, but it’s not guaranteed. As we’ve mentioned before, corals are animals with plants (microscopic algae) living inside them. That algae is what gives corals their food to survive through photosynthesis.
When ocean temperatures are too hot for corals, they respond similarly to humans when we get sick. Our bodies’ white blood cells start attacking parts of our own body to identify the problem.
In like fashion, as temperatures climb, coral expels that symbiotic alga (revealing their limestone skeleton), ideally until water temperatures return to ideal.
However, if that doesn’t happen soon enough, the coral will starve given the algae is what provides coral with food to live.
Coral bleaching is occurring more frequently as ocean temperatures are climbing. While previously thought of as a “hundred-year flood” type event, we’ve had several since the late 90s.
How to Save Coral Reefs
If we take sufficient action, there is still enough time to protect the coral reefs we have and work on restoring those we’ve lost.
For an incredible list of action items to protect and restore our coral reefs and the marine life that depend on them, check out this Nexus Page from Regeneration.org.
Quit Stressing Me Out
How to Restore the World’s Dying Coral Reefs
Our world’s coral reefs are not only breathtakingly beautiful but also crucial to the livelihoods of over a billion people across 100 nations.
They provide natural flood defense, support millions of fishers, and even have medicinal benefits.
However, these incredible ecosystems are facing grave threats, with half already dead and projections suggesting over 90% could be lost by 2050.
But amidst this seemingly bleak situation, there are many, like the co-founders of Coral Vita, who have dedicated their lives to restoring and protecting coral reefs.
Check out this episode where we discuss good stress, bad stress, and how understanding the difference between the two can help us in our goal to restore the world’s dying reefs.