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Florida's Coral Reefs

Florida is the only state in the continental United States with extensive shallow coral reef formations near its coasts. Coral reefs create specialized habitats that provide shelter, food, and breeding sites for numerous plants and animals. This includes ones important to fishing like spiny lobster, snapper, and grouper. Coral reefs lay the foundation of a dynamic ecosystem with tremendous biodiversity. The Florida Reef Tract stretches approximately 360 linear miles from Dry Tortugas National Park west of the Florida Keys to the St. Lucie Inlet in Martin County. Roughly two-thirds of the Florida Reef Tract lies within Biscayne National Park and the Florida Keys National Marine Sanctuary, a marine protected area that surrounds the Florida Keys island chain. The reefs stretching north of Biscayne National Park and the marine sanctuary are managed by the Florida Department of Environmental Protection's Coral Reef Conservation Program with insight from the Southeast Florida Coral Reef Initiative, which is one of several programs administered by the Coral Reef Conservation Program.

Florida's coral reefs came into existence approximately 10,000 years ago when sea levels rose following the last Ice Age. Reef growth is relatively slow; individual colonies grow only one-half inch to seven inches a year, depending on the species. Coral reefs are in a constant state of flux, where new polyps (the living tissue) grow on the outer surface, while their skeleton erodes to help make the white sand for our beaches. During long periods of favorable conditions, the reefs may reach awe-inspiring heights and diversity.

Corals are animals that have a symbiotic relationship with a microscopic algae called zooxanthellae. The corals benefit from the nutrients and oxygen that the zooxanthellae provide through photosynthesis, and the zooxanthellae receive nutrients and protection from the corals. The zooxanthellae give the corals their beautiful spectrum of colors.

Coral reef development occurs only in areas with specific environmental characteristics: a solid structure for attachment, relatively high water temperatures, clear waters low in phosphate and nitrogen nutrients, and moderate wave action to disperse waste and bring oxygen and plankton to the reef. Most of Florida's sport fish species and many other marine animals spend significant parts (particularly during their younger development stages) of their lives on or around coral reef ecosystems.

Types of Reefs and Corals

The three major types of coral reefs around the world are atolls, fringing reefs and barrier reefs. Florida's coral reef system most closely resembles a barrier reef; however, the reefs are closer to shore and they lack the shallow inshore lagoons found on most barrier reefs. For this reason, the Florida Reef Tract is more aptly referred to as a bank reef. Florida also has patch reefs, which grow in shallower water in between the reef tract and land. Patch reefs are typically small (the size of a backyard or a small home).

Corals can generally be divided into two main categories: stony corals and octocorals (sea fans, sea whips and other soft corals). More than 45 species of stony corals and 35 species of octocorals are found along the Florida Reef Tract. Each kind lives in a separate colony that is shaped differently.Marine sponges are also very important within the coral reef community, and more than 70 species can be found along the Florida Reef Tract.

Stony corals are the major reef architects. Polyps, the living portion of corals, extract calcium from seawater and combine it with carbon dioxide to construct the elaborate limestone skeletons that form the reef backbone.

Historically, Florida's reef-building corals were brain, star and elkhorn; all are not as common now as they once were. Brain coral is dome-shaped and has the waves, folds and ridges that resemble those of a human brain. Star coral is also dome-shaped, but has a distinctive star pattern on its surface that is caused by the accordion-like folds within its polyp cups. Elkhorn and a similar coral called staghorn are so named because their branchlike projections resemble the antlers of those animals. In recent years, corals have experienced declines due to a combination of factors including coral disease, coral bleaching, high ocean temperatures and human impacts. In 2006, elkhorn and staghorn coral were listed as threatened species under the Endangered Species Act. To help replace these corals that were once so abundant, coral nurseries have been established along Florida's coast and in the Florida Keys. Nurseries are growing new colonies and successfully out-planting them to locations where they had once flourished, but the threats still remain.

Last Modified:
September 6, 2017 - 3:29pm

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