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South Florida Aquatic Environments

Coral Reefs



IMPORTANCE OF CORAL REEFS
Hurricane Cloud Formation
courtesy SeaWIFS/NASA
Hurricane-NASA


Natural impacts on corals include:

Storms

  • Storms and hurricanes may cause extensive damage to reef structures and communities
Although much of coral reef destruction is blamed on human activity, natural disturbances are also capable of causing extensive damage to coral reefs. Strong waves caused by storms and hurricanes may smash into the reef, breaking up large corals and creating rubble fields. Storms also harm reefs indirectly by disrupting nearshore habitats, resulting in the release of large amounts of sediments and freshwater to come into contact with the reef. These disturbances open spaces for new organisms to colonize, preserving overall biodiversity.

Coral Bleaching
courtesy U.S. Geological Survey
Bleaching

Thermal Stress

  • Thermal stress can induce the loss of symbiotic algae from corals, often referred to as "coral bleaching"
Heat-related stress often occurs during late summer months when the sun is intense. Corals can survive water temperatures as high as 86-95F (30-35C), depending upon the species. Increases in water temperature often causes loss of symbiotic algae from coral tissues, referred to as coral bleaching. Corals are also susceptible to cold stress at temperatures at or below 57F (14C). Cold water masses originate in Florida Bay, causing coral death in patch reefs long the water current's path. However, most offshore corals experience little damage due to the mixing of the cold water current with the warm offshore waters, moderating temperatures and lessening the impact on surrounding reefs.

Sea Urchin - Diadema antillarum
© James L. Van Tassell
Diadema

Diseases

  • Coral reef organisms, such as the long-spined sea urchin, are susceptible to many pathogens
Along with coral bleaching, black band disease, and white band disease, coral reef organisms are subject to many pathogens. During the 1980s, a water-borne pathogen caused the massive die off of the long-spined sea urchin, Diadema antillarum. Long-spined sea urchin populations were reduced as much as 95% in some locations. This urchin is an important herbivore, keeping algae growth in control in reef habitats. The decline in sea urchin populations resulted in algal overgrowth throughout the reefs of the Caribbean.