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South Florida Aquatic Environments

Coral Reefs

Florida Keys Reef Scene
Florida Keys Reef Scene
© Doug Weaver, U.S. Geological Survey


Coral Reefs:

What is a Coral Reef?

  • Coral colonies made of many individual coral polyps
  • Corals produce calcium carbonate skeletons
  • Symbiotic algae provide nutrition to corals
Coral reefs are among the most diverse communities on this planet, often described as "rainforests of the sea". Reefs occur in clear, shallow waters throughout tropical regions across the globe. Formed by the calcium carbonate skeletons, the backbone of the reef is built by tiny coral animals that make up large coral colonies. Coralline algae produce calcium carbonate, which cements the coral skeletons together, forming the continuous reef structure. The skeletons of tube worms, mollusks, and other organisms also become incorporated into the reef.

pillar coral
Pillar Coral
courtesy Florida Keys National Marine Sanctuary

Tube Coral
courtesy South Florida Water Management District

Scientific Classification

  • Corals are part of a group of organisms called Cnidarians
  • This group includes jellyfish, sea anemones, and sea fans
The classification Cnidarian includes:


The reef-building corals can be identified by their stony skeletons made of calcium carbonate. A coral colony consists of thousands of individual coral animals, each similar in appearance to a small sea anemone with its base attached to a calcareous cup. Corals are armed with a ring of tentacles used to capture zooplankton from the surrounding water. Reef-building corals also contain symbiotic algae, called zooxanthellae, within their tissues. These single-cell algae have a mutualistic association with the coral hosts, a relationship that benefits both partners. The algae utilize carbon dioxide and nitrogen-based waste products released from the coral. In return, the algae perform photosynthesis, producing sugars and amino acids. These products are transported to the coral in support of its nutritional needs.

Florida Coral Reef Biodiversity
courtesy NOAA
Florida Coral Reef Scene

Importance

  • Reefs provide habitat and nursery areas for many organisms
Coral reefs are important habitat and nursery grounds for fishes and invertebrates, including those of commercial and recreational value. They are closely associated with mangrove and seagrass communities, providing protection from wave and storm damage. Disturbances to reefs may result in upsetting the ecological balance of the reef as well as having indirect impacts on other nearby habitats.