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CORAL REEF COMMUNITIES
Hardbottom Community
courtesy NOAA
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Coral reef communities within Florida waters are categorized as:
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Hardbottom Community
- Close to shore
- Low species diversity
- Dominated by gorgonians, algae, and sponges
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Hardbottom reef communities are found close to shore over limestone rock covered by a thin sandy layer. Hardbottom communities have low species diversity, dominated by gorgonians, algae, sponges, and a few stony coral species. Hardbottom habitats provide important cover and feeding areas for many fish and invertebrates.
Gorgonian
courtesy Florida Keys National Marine Sanctuary
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Hardbottom communities are often divided into two types:
- Nearshore restricted hardbottom communities are subject to limited water movement. This bottom community is dominated by algae including epilithic algae that attaches itself directly to the limestone bottom as well as drift algae.
- Nearshore high-velocity hardbottom communities are exposed to strong currents. Gorgonians, easily recognized with their rod-like appearance and flexibility, and sponges dominate these communities.
Brain Coral
© Eugene Weber, California Academy of Sciences
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Stony corals have adaptations, including a mucous layer used to removed sediments from their polyps, enabling them to survive in these communities.
These coral species include:
- smooth starlet coral (Siderastrea radians)
- mustard hill coral (Porites asteroides)
- golfball coral (Favia fragum)
- elliptical star coral (Dichocoenia stokesii)
- common brain coral (Diploria strigosa)
Spiny Lobster
courtesy NOAA
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French Grunt
© Dr. Antonio J. Ferreira, California Academy of Sciences
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A variety of other animal species, including anemones, mollusks, crabs, seastars, sea cucumbers, spiny lobsters, and fish, are associated with hardbottom communities. Fish that forage in these areas include grunts (Haemulon spp.),
snappers (Lutjanus spp.), groupers (Epinephelus spp.), and
great barracudas (Spyraena barracuda). Tangs (Acanthurus coeruleus) and surgeonfish (Acanthurus bahianus) form large feeding schools over hard botttoms.
Flamingo Tongues Living On A Gorgonian
courtesy Florida Keys National Marine Sanctuary
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Gorgonians provide an increase in surface area for attachment of invertebrates including tunicates, anemones, mollusks, and worms.
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