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What is a Coral Reef?

Diana Bocco
Diana Bocco

A coral reef is a sea structure made out of living organisms that form a wall together. Stony corals are usually the main organism found in a reef, but other types of skeletal material also join together to form the thick walls. It is also "constructed" by the thousands of fish, sponges, and sea urchins grazing around the area. As these organisms move about, they actually help the reef settle and gain a more stable structure. Waves are also partly responsible for the wall's size and format, as they affect the geology of the formation.

This living structure is very effective at absorbing nutrients from the waters surrounding it. This includes obtaining phosphorus and nitrogen from sea waters, and other nutrients from small organisms making their home in it. A coral reef is one of the largest living communities in the world. Thousands of species make their home there, including over 4,000 different tropical fishes, jellyfish, crabs, sea urchins, and starfish. Mammals may visit, but none actually live on or near it.

A coral reef is composed of living organisms that have fused together.
A coral reef is composed of living organisms that have fused together.

91.9 percent of the world's coral reef mass is situated in the Indo-Pacific region, with Australia taking a major percentage of that. There are basically none of these structures on the American west coast or on upper Asia, including Russia. This is mainly due to cold waters, but also to the effect of powerful water currents in the area.

Humans are the biggest threat to the integrity of a coral reef. Because of pollution, boat traffic, and aggressive fishing, reefs are now considered in danger and are protected under the Great Barrier Reef Marine Park Authority, an Australia-based institution. The illegal trade on saltwater aquarium fish is also a major factor on their destruction, as little can be done to stop collectors from around the world to request exotic, pricey species.

Jellyfish live in coral reefs.
Jellyfish live in coral reefs.

A coral reef is also susceptible to major environmental changes, including global warming, which affects water currents and marine migration. Coral bleaching, a form of erosion, occurs when water temperatures reach higher-than-normal levels. This can prove disastrous for a reef.

Frequently Asked Questions

What exactly is a coral reef?

A coral reef is a diverse underwater ecosystem characterized by reef-building corals. Corals are marine invertebrates that form large colonies of individual polyps, secreting calcium carbonate to create hard skeletons. These structures provide habitat and shelter for many marine species, making coral reefs among the most biodiverse ecosystems on Earth.

How do coral reefs form?

The bright colors exhibited by most species of coral provide excellent camouflage opportunities for marine species.
The bright colors exhibited by most species of coral provide excellent camouflage opportunities for marine species.

Coral reefs begin when free-swimming coral larvae attach to submerged rocks or other hard surfaces along the edges of islands or continents. As these corals grow and multiply, they form colonies and build up skeletal material over many years, creating the complex, three-dimensional structures that constitute a reef.

Why are coral reefs important to the marine environment?

An atoll is a ring-shaped coral reef that surrounds a central lagoon.
An atoll is a ring-shaped coral reef that surrounds a central lagoon.

Coral reefs are crucial for marine life, serving as a habitat for approximately 25% of all marine species despite covering less than 1% of the ocean floor. They provide food, spawning grounds, and protection for a vast array of organisms. Additionally, reefs contribute to nutrient cycling and carbon dioxide absorption, supporting overall ocean health.

What threats do coral reefs face?

Crabs might be found in coral reefs.
Crabs might be found in coral reefs.

Coral reefs are threatened by a range of human-induced factors, including climate change, which leads to coral bleaching and ocean acidification; overfishing, which disrupts ecological balance; coastal development, which results in habitat destruction; and pollution, which can cause disease and death in coral populations. These threats jeopardize the survival of reefs globally.

Can coral reefs recover from damage?

Coral sometimes appears in a fan shape.
Coral sometimes appears in a fan shape.

Coral reefs can recover from damage if conditions improve and stressors are removed. Recovery processes can take decades, as corals grow slowly. Active restoration efforts, such as coral gardening and artificial reefs, can aid recovery. However, the resilience of coral reefs is limited, and repeated or prolonged disturbances can lead to irreversible damage.

How can we protect coral reefs?

Protecting coral reefs involves reducing global carbon emissions to mitigate climate change, establishing marine protected areas to conserve reef ecosystems, regulating fishing practices, controlling pollution, and supporting reef restoration projects. Public education and sustainable tourism also play vital roles in promoting the conservation of these precious marine habitats.

Discussion Comments

Georgesplane

@ Parmnparsley and Amphibious54 - The biggest immediate threat to the Florida Barrier Reef system is the ongoing oil spill in the Gulf of Mexico. The Deepwater Horizon Oil Spill perpetuated by failures in BP's, Halliburton's, and Transocean's processes to safely drill for oil has the potential to completely destroy, as Amphibious54 stated, the world's third largest barrier reef system.

Coral reefs are actually created through a process that relies on the symbiotic relationship between coral polyps and zooxanthellae algae. This makes corals hypersensitive to anything that affects the oxygen content, temperature, bacterial formation, and light saturation of the water. The oil from the Deepwater spill has the potential to affect all of the above; essentially suffocating the reef, and destroying thousands of years of reef building. This is something that money cannot fix.

Amphibious54

There is not much difference between barrier reefs and coral reefs. Coral reefs are any type of reef that is formed by the calcium carbonate deposits of coral polyps. Barrier reefs are reefs that form a protective barrier to a land mass. Barrier reefs usually run parallel to a nearby land mass and form protective lagoons. Barrier reefs are important because they create the protective spawning grounds for fish and create one of the oceans largest ecosystems. The reefs at Dry Tortuga are actually part of a barrier reef system that runs along the Florida Keys; creating the world's third largest Barrier reef next to the Great Barrier Reef, and the Belizian Barrier Reef.

parmnparsley

What is the difference between a barrier coral reef and a coral reef? Is one more ecologically important than another? I once went to the Dry Tortugas national park in the Florida Keys and saw the reefs there. They were Amazing! I would hate to see these reefs destroyed, but I always hear about things like coral bleaching, and hurricane damage to coral reefs What are some of the biggest challenges in protecting Florida's reefs?

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    • A coral reef is composed of living organisms that have fused together.
      By: Richard Carey
      A coral reef is composed of living organisms that have fused together.
    • Jellyfish live in coral reefs.
      By: vilainecrevette
      Jellyfish live in coral reefs.
    • The bright colors exhibited by most species of coral provide excellent camouflage opportunities for marine species.
      By: pirosa
      The bright colors exhibited by most species of coral provide excellent camouflage opportunities for marine species.
    • An atoll is a ring-shaped coral reef that surrounds a central lagoon.
      By: barefootpilot
      An atoll is a ring-shaped coral reef that surrounds a central lagoon.
    • Crabs might be found in coral reefs.
      By: raptorcaptor
      Crabs might be found in coral reefs.
    • Coral sometimes appears in a fan shape.
      By: LA Photographer
      Coral sometimes appears in a fan shape.