2010-252A (09) - Laserfiche WebLink

Home Browse Search

Comprehensive Plan Conservation Element The Indian River Lagoon and associated estuarine wetlands are part of a major ecological system that supports hundreds of species of fish, plants and animals. According to the Indian River Lagoon Comprehensive Conservation and Management Plan, the IRL has more species of fish, plants, and animals than any other estuary in the United States. Also, the IRL supports thirty-seven (37) rare and endangered species, including one quarter (1/4) to one third (1/3) ofthe Florida manatee (Trichechus manatus) population in the United States. The natural ecological communities that comprise the IRL system are: high salt marshes, mangrove swamps, open water, exposed sand -shell bottoms, drift algae, and submerged aquatic vegetation. Mosquito impoundments and spoil islands are the anthropogenic features present in the IRL. Each of these communities has separate characteristics and functions; however, the boundaries of these communities overlap and are not clearly defined. Combined, these ecological communities form the basis for the most diverse estuary in North America. - Exposed Sand -Shell Bottom The exposed sand -shell bottom forms the most extensive area of the IRL system. Within this system, substrate firmness, stability and the percentages of silt, sand and shell material are extremely variable. Macroinvertebrate burrowing forms of life, such as segmented worms, brittle stars, bivalves, acorn worms, and gastropods, comprise the dominant species. The exposed sand -shell bottom of the IRI, lacks rooted plants; however, these areas often support algae communities attached to shell, rock, or other firm surfaces. Exposed sand -shell bottoms less than five feet in depth provide potential sites for colonization of submerged aquatic vegetation (SAV) as unconsolidated sediments stabilize. Oyster flats and bars are exposed sand -shell bottoms where self-perpetuating oysters dominate. These areas provide attachment and protective cover sites for invertebrates and small cryptic fish such as gobies and blennies. The invertebrate community in turn provides a forage base for a variety of fish. Nearly half of all fish species in the IRL can be found on or over the exposed sand -shell bottom community (Woodward -Clyde, 1994). Fish species most often associated with this community include: sheephead, spade fish, grey snapper, tarpon, snook, and barracuda. - Drift Algae Communities As the term "drift algae" implies, this community is formed of unattached, free drifting algae, which aggregate in response to prevailing winds, water currents, and bottom topography. Due to their drifting characteristics, drift algae can be associated with exposed sand -shell bottoms or with seagrass bottoms. Drift algae occurs throughout the IRL, but particularly large and persistent aggregations occur south of Sebastian Inlet and north of Vero Beach. Community Development Department Indian River County 61