The Vital Importance of Coral Reefs

Coral reefs are the ocean’s nurseries, essential to the survival of countless marine species and a critical component of global ecosystems. These vast, biodiverse structures serve as breeding grounds for various life forms, offering food and shelter from predators to resident and non-resident fish, marine invertebrates, and other ocean life.

Although they cover less than 10% of the ocean floor, coral reefs are the largest living organisms on Earth. Often mistaken for plants, corals are animals that have existed for over 500 million years, long before dinosaurs or humans walked the planet. Despite their long history, human activities severely threaten coral reefs.

Coral Life and Biodiversity

Reefs are bustling hubs of biodiversity where species such as fish, clams, sea urchins, oysters, and other marine creatures begin life. Within the safety of these underwater ecosystems, marine creatures find nourishment and protection from predators. This sheltered environment allows them to grow to maturity, hidden among the corals and aquatic plants.

Vermont’s Chazy Reef, which was formed 500 million years ago, is a remarkable example of ancient coral life. The remnants of this reef are still viewable today, offering an excellent glimpse into the distant past. Smithsonian Magazine has an insightful article about the significance of the Chazy Reef.

Type of Corals

Corals are divided into two main types:

1) Hard Corals

Endangered Elkhorn hard coral (Acropora palmata) is one of the most important reef-building corals in the Caribbean. Image by John A. Anderson/Depositphotos

Hard, or stony, corals form the iconic reef structures we see today by building calcium carbonate (CaCO3) skeletons in a stable crystal form called aragonite. Notable examples include Staghorn and Elkhorn corals, with the endangered Elkhorn coral playing a critical role in Caribbean reef-building.

2) Soft Corals

Pink soft coral. iStock.com/DanSchmitt

Soft corals do not build hard skeletons but gather into colonies, creating forms resembling fans, bushes, and trees. Although present in reefs, they do not contribute to forming the complex reef structures seen with stony corals.

How Coral Reefs Form

Coral Anatomy. Structure of coral polyp. Image by Zhabska T.S/Depositphotos

Corals begin with polyps, a type of invertebrate that is usually small but can be up to a foot in diameter in some species. Polyps are soft animals with a mouth and tentacles and are temperature-sensitive.

Indonesian Zoanthus polyps colony. Image by Vojce/Depositphotos

Growing in shallow waters warmed by the sun, they use the calcium carbonate found in seawater to form hard skeletons. Their slow rate of growth, even with optimal conditions, annually only adds anywhere from 1/10th of an inch to almost 4 inches. While they can exist individually, most corals form into large reef colonies of four types: fringing, barrier, atoll, or patch reefs.

With such super slow growth rates, extensive coral reefs can take up to ten thousand years or more to form, even when water temperatures, currents, nutrients, light, and a lack of disease are all present. When these conditions are met, polyps produce gargantuan reefs over many centuries. The Great Barrier Reef, Australia’s largest of them, is over 1200 miles long and covers around 125,000 square miles.

The Importance of Coral Reefs to the Ecosystems

Corals and school of snappers in shallow Bahamian waters. iStock.com/Strmko

According to a 2021 Pacific Symposium on Biocomputing, “Coral reefs are home to over 2 million species and provide habitat for roughly 25% of all marine animals, but they are being severely threatened by pollution and climate change”. The United States National Ocean and Atmospheric Administration (NOAA) also emphasizes that “Coral reefs support more species per unit area than any other marine environment, including about 4,000 species of fish, 800 species of hard corals, and hundreds of other species.”

The destruction of these ecosystems would have devastating effects on both ocean species and humanity, with consequences that are still not fully understood. Over a billion people rely on coral reefs for food, employment, and income. Without these ecosystems, fisheries that harvest crabs, clams, oysters, lobsters, and numerous fish species would collapse. The loss of coral reefs would be a tragic blow to marine life and cause widespread economic damage, particularly in regions dependent on fishing and tourism.

Coral reefs also act as natural coastal barriers, protecting wetlands and shorelines from storms, particularly during hurricanes. The importance of reefs cannot be overstated; if destroyed, the consequences for marine life, global ecosystems, and human societies would be catastrophic.

What Is Destroying the Coral Reefs?

Dead staghorn coral killed by bleaching on the northern Great Barrier Reef, November 2016. Credit: Greg Torda, ARC Centre of Excellence for Coral Reef Studies, CC BY-ND 2.0 via flickr

Coral reefs are threatened by human activities, particularly the burning of fossil fuels, which releases massive amounts of carbon dioxide (CO2) and methane (CH4) into the atmosphere. Methane is emitted from both human-influenced (anthropogenic) and natural sources. While methane remains in the atmosphere for only a few decades, it is 25 times more potent than CO2 in warming the planet’s atmosphere. Quick reductions in methane emissions could yield rapid, positive effects on global warming.

CO2, emitted from burning fossil fuels for transportation, electricity, and heating, is also driving the destruction of coral reefs. The combined emissions of methane and CO2 are a one-two punch to coral ecosystems. Without urgent reductions in fossil fuel use, reefs will continue to die off, unable to adapt to the rapidly changing environment.

Time to Act

Despite their beauty and critical importance, coral reefs are disappearing alarmingly. If we do not act quickly to reduce fossil fuel use and combat climate change, the world’s coral reefs and those that rely on them will be lost forever. Protecting coral reefs is about saving marine life and securing the livelihoods and survival of millions of people worldwide. Now is the time to act.

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