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Natural Communities of Biscayne Bay Aquatic Preserves Quick Links
Hardbottom community

Hardbottom community

  • Consolidated Substrate
    Consolidated substrates, also known as hardbottom communities, are mineral based natural communities generally characterized as expansive, relatively open areas of subtidal, intertidal, and supratidal zones which lack dense populations of sessile plant and animal species. Consolidated substrates are solidified rock or shell conglomerates and include coquina, limerock or relic reef materials. These communities may be sparsely inhabited by sessile, planktonic, epifaunal, and pelagic plants and animals but house few infaunal organisms (i.e., animals living within the substrate). Consolidated substrates are important in that they can form the foundation for the development of other marine and estuarine natural communities.
  • Unconsolidated Substrate
    Unconsolidated substrates or soft bottom communities are mineral based natural communities generally characterized as expansive, relatively open areas of subtidal, intertidal, and supratidal zones which lack dense populations of sessile plant and animal species. Unconsolidated substrates in Biscayne Bay originate from calcium carbonate depositions of plants or animals. This community may support a large population of infaunal organisms as well as a variety of transient planktonic and pelagic organisms (e.g., tube worms, sand dollars, mollusks, isopods, amphipods, burrowing shrimp, and an assortment of crabs).
Blue goby on boulder brain coral

Blue goby on boulder brain coral

  • Coral Reef
    Coral reefs are animal-based natural communities generally characterized as expansive conglomerates of hard, sessile, limestone-building coral occurring in warm subtidal waters. Coral reefs are formed from a diverse assemblage of carbonate precipitating organisms of the phylum Cnidaria. This community includes the class Hydrozoa and the subclass Zoantharia within the class Anthozoa. Hydrozoa includes fire coral, are important fast growing, colonial reef builders that are capable of withstanding temperate water temperatures. Fire coral are distributed as far north in Florida as Tarpon Springs in the Gulf of Mexico and at least to Cape Kennedy in the Atlantic Ocean. The Scleractinians, or true stony coral, are the primary hermatypic or reef building coral within the subclass Zoantharia. Within the BBAP, stony corals are found in individual colonies, not in true reef formations, except the offshore portion east of Key Biscayne where patch reefs have been identified. Lesser starlet coral (Siderastrea radians) dominates the northern part of the BBAP. In the Card Sound portion the following species have been observed: rose coral (Manicina areolata), fire coral (Millepora alcicornis), finger coral (Porites porites), massive starlet coral (Siderastrea siderea) and knobby star coral (Solenastrea hyades).
  • Octocoral Reef
    Octocoral beds are soft animal-based natural communities characterized as large populations soft corals such as gorgonians, sea fans, sea feathers, sea fingers, sea pansies, sea plumes, sea rods, and sea whips. This community is confined to the subtidal zone since the sessile organisms are highly susceptible to desiccation. An assortment of benthic and pelagic animals (e.g., sea anemones, sponges, mollusks, tube worms, burrowing shrimp, crabs, isopods, amphipods, sand dollars, and fishes) are associated with octocoral beds. Sessile and drift algae can also be found scattered throughout octocoral beds. Octocoral beds require consolidated substrate on which to anchor.
Oysters on mangrove roots

Oysters on mangrove roots

  • Mollusk Reef
    Marine and estuarine mollusk reefs are animal-based natural communities typically characterized as expansive concentrations of sessile mollusks occurring in intertidal and subtidal zones. In Florida, the most developed mollusk reefs are generally restricted to estuarine areas and are dominated by the American oyster. Mollusk reefs present a dynamic community of estuarine ecology, forming refugia, nursery grounds, and feeding areas for a myriad of other estuarine organisms. The mollusk reef is the rarest natural community in BBAP. American oysters are found attached to mangrove roots and structures built in the bay, but oyster reef formation is limited to upstream areas of the Oleta River possibly due to increased salinity.
Sponge bed

Black ball sponge

  • Sponge Bed
    Marine and estuarine sponge beds are soft animal-based natural communities characterized as dense populations of sessile invertebrates of the phylum Porifera, Class Demospongiae. The dominant animal species are sponges such as branching candle sponge, Florida loggerhead sponge and sheepswool sponge. Sponge beds are confined primarily to subtidal zones. Other sessile animals typically occurring in association with these sponges are stony corals, sea anemones, mollusks, tube worms, isopods, amphipods, burrowing shrimp, crabs, sand dollars, and fishes. Sessile and drift algae can also be found scattered throughout sponge beds. Sponge beds require consolidated substrate on which to anchor.
Parchment worms

Parchment worms

  • Worm Reef
    Substantial subtidal or intertidal area with relief from concentrations of sessile, tubicolous organisms of the Phylum Annelida, Class Polychaeta (e.g., chaetopterids and sabellarids); octocorals, sponges, stony corals, macrophytic algae and seagrasses sparse, if present.
Puffer in algal bed

Southern puffer in a macroalgae community

  • Algal Bed
    Algal beds are plant-based natural communities characterized as large populations of nondrift macro or micro algae. This community may occur in subtidal, intertidal, and supratidal zones on soft and hard bottom substrates. Seagrasses may occur in algal beds associated with soft bottoms. Sessile animals associated with algal beds will vary based on bottom type. For algal beds associated with hard bottom substrate, animal populations will be similar to populations associated with octocoral beds and sponge beds. Those associated with soft bottom substrate may have similar benthic and pelagic species in addition to infauna species. Recent research has shown that algal beds provide critical habitat for juvenile spiny lobsters, a species of great commercial importance.
Seagrass beds and beach dunes

Sand dunes and seagrass beds at Bill Baggs Cape Florida State Park

  • Seagrass Bed
    Seagrass beds are plant-based natural communities typically characterized as expansive stands of vascular plants. This community occurs in subtidal (rarely intertidal) zones, in clear, coastal waters where wave energy is moderate. Seagrasses are not true grasses. The three most common species of seagrasses in Florida are turtle grass, manatee grass, and shoal grass. Nearly pure stands of any one of these species can occur, but mixed stands are also common. Together, seagrasses and their epiphytes serve as important food sources for manatees, marine turtles, and many fish. The dense seagrasses also serve as shelter or nursery grounds for many marine invertebrates, and fish. Marine and estuarine seagrass beds occur most frequently on unconsolidated substrates of marl, muck or sand, although they may also occur on other unconsolidated substrates. The dense blanket of leaf blades reduces the wave-energy on the bottom and promotes settling of suspended particulates. The dense roots and rhizomes of the seagrasses stabilize settled particles. Thus, marine and estuarine seagrass beds are generally areas of soil accumulation. beds in BBAP include Johnson's grass, which is listed as Threatened. The distribution of Johnson's grass is from northern Biscayne Bay, through Broward and Palm Beach inshore waters, to St. Lucie Inlet of the Indian River in Martin County. BBAP from the Rickenbacker Causeway northward is listed as part of the species' critical habitat.
  • Salt Marsh
    Salt marsh is a largely herbaceous community that occurs in the portion of the coastal zone affected by tides and seawater and protected from large waves, either by the broad, gently sloping topography of the shore, by a barrier island, or by location along a bay or estuary. The width of the intertidal zone depends on the slope of the shore and the tidal range. Salt marsh may have distinct zones of vegetation; each dominated by a single species of grass or rush. Little salt marsh and no freshwater marsh remain adjacent to Biscayne Bay. Some salt marsh is remnant in the Deering Estate North Addition, but additional marsh at the Estate and adjacent to Oleta River State Park are restored areas.
Red and black mangroves

Red and black mangroves

  • Mangrove Swamp
    Mangrove swamp is a dense forest occurring along relatively flat, low wave energy, marine and estuarine shorelines. The dominant plants of mangrove swamp are red mangrove (Rhizophora mangle), black mangrove (Avicennia germinans), white mangrove (Laguncularia racemosa) and buttonwood (Conocarpus erectus). Red mangrove often dominates the lowest (or deep-water) zone, followed by black mangrove in the intermediate zone, and white mangrove and buttonwood in the highest, least tidally-influenced zone. The density and height of mangroves and the diversity of associated herbaceous species can vary considerably within a mangrove swamp. The mangroves lining Biscayne Bay were used by ancient civilizations, dating back to the Glades cultures, 3,000 years ago. Mangroves provide protected nursery habitat for numerous recreational and commercial fish and invertebrates in Biscayne Bay including snook, tarpon, oysters, crabs and shrimp. Large-scale clearance of these trees around Biscayne Bay did not begin until after the railroad arrived and the City of Miami incorporated in 1896.
  • Composite Substrate
    Composite substrates consist of a combination of natural communities such as "beds" of algae and seagrasses or areas with small patches of consolidated and unconsolidated bottom with or without sessile floral and faunal populations. Composite substrates may be dominated by any combination of marine and estuarine sessile flora or fauna, or mineral substrate type. Typical combinations of plants, animals and substrates representing composite substrates include soft and stony corals with sponges on a hard bottom such as a limerock outcrop; algae and seagrasses scattered over a sand bottom; and patch reefs throughout a coralgal bottom. Any of the remaining marine and estuarine natural communities can grade into composite substrate communities.

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Last updated: June 27, 2014

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