Florida Keys National Marine Sanctuary

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Chapter 3. SITE DESCRIPTION

c - Biological features

Habitats

Brief description of dominant and particular habitats (marine and terrestrial)*: List here the habitats and ecosystems that are representative and/or of importance for the WCR (i.e. mangroves, coral reefs, etc):


The biological diversity that the region supports makes the Keys' ecosystem ecologically, economically, aesthetically, and biogeographically unique within the United States.

The freshwater, estuarine, and saltwater wetlands of the Lower Everglades/South Peninsular Florida region provide a variety of habitat features that encourage a complex mixture of invertebrates, fishes, amphibians, reptiles, birds, and mammals. In addition, the area's diverse wetland and successional communities provide food, shelter, and nesting sites for many resident and migratory organisms.

Florida Bay's mangrove islands and seagrass beds are highly productive, faunally rich ecosystems that provide food, protection, and nesting sites for many species of fishes, amphibians, reptiles, birds, and mammals. These areas are critically important to commercial and recreational fish species, as 70 to 90 percent of the harvested species in the Gulf depend on coastal wetlands and seagrass beds during at least part of their life cycle. The shallow mud banks are essential for various species of wading birds, as they provide the only feeding access to the bay's fish populations.

The Keys' nearshore habitats and tidal channels are transitional areas of species mixing between the Gulf and the Atlantic, and the presence or absence of tidal passes, coupled with their bathymetric features (e.g., depth, width, current velocity, etc.), plays an important role in the distribution of biota and the establishment of marine communities within the Sanctuary. The region is an area of ecological and biological mixing where the temperate waters of the Gulf meet the tropical waters of the Atlantic, producing one of the most complex habitats in the Sanctuary. The majority of the commercially and recreationally important species in the region forage and seek shelter in the nearshore habitat both in their early life stages and as adults.

Major Atlantic Ocean habitats include: 1) the mangrove fringe and nearshore hardbottom; 2) inshore patch reef; 3) Hawk Channel (mid-channel) reef; 4) Hawk Channel (mid-channel) seagrass and softbottom; and 5) reef tract habitats. The complex reef tract community is composed of habitats including offshore patch reef, seagrass, back reef/reef flat, bank reef/transitional reef, intermediate reef, deep reef, outlier reef, and sand and softbottom environments.

The region's reefs are highly complex and diverse communities whose success is limited by the presence of suitable substrate and a narrow range of environmental and hydrographical parameters. Corals are the principal builders of the reef community and form the main source of spatial complexity and shelter. Biogeographic and environmental factors determine the density and diversity of the species on coral reefs.

Detail for each habitat/ecosystem the area it covers:

Marine / coastal ecosystem categories
Detail for each habitat / ecosystem the area covers
Size (estimate) Description and comments
unit Area covered
Mangroves
Mangroves ha 95000
Coral reefs
Bank Barrier Coral Reefs ha not given Bank Barrier Coral Reefs 356 km long
Sea grass beds
Seagrass beds ha 1000000
Other marine ecosystems
Marine surface ha 994700
Terrestrial ecosystems
Size (estimate)
unit Area covered