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Salt Marsh Most of the estuarine habitat of the northwest Florida, Gulf of Mexico Big Bend is bordered by intertidal salt marshes, primarily Spartina alterniflora at the shoreline then S. patens, Salicornia virginica and Juncus roemerianus to landward. These plants are adapted to rapid and sometimes extreme variation in salinity, temperature, and dissolved oxygen, allowing them to dominate this biotope. After salt marsh plants slough leaves or die, their material is broken down by bacteria to form detritus. In this form, the salt marsh nutrients fuel food webs both within the marsh and in the adjacent waters. Detritus, diatoms and other microorganisms in the marsh are the food source for dense populations (hundreds per square meter) of fiddler crabs, Uca spp. and marsh periwinkles, Littoraria irrorata, as well as clams, mussels, and other invertebrates. Nutrients that are washed out to sea support the food chain of pelagic larvae of fish and commercial shrimp. Many marsh creeks also host oyster (Crassostrea virginica) reefs that form an important substrate and habitat for many invertebrates and fishes. All of the above elements are highly interactive and constitute an exceedingly productive ecosystem. The ecological functions of salt marsh also include the provision of nursery and adult habitat for invertebrates, fish, and birds; protection of shorelines from erosion; and removal of excess nutrients from the water column.
Seagrass Beds
The seagrass meadows of the northwest Florida coast form the only structurally complex habitat in these waters. These meadows are dominated by turtle grass Thalassia testudinum, followed by shoal grass Halodule wrightii, manatee grass Syringodium filiforme, and widgeon grass Ruppia maritima. Turtle grass forms particularly dense beds directly west of the Florida State University Coastal and Marine Laboratory (FSUCML) off Lanark, whereas shoals grass is locally dominant in areas of physical disturbance or areas exposed to salinity and temperature stress. Manatee grass occurs at greater depths than turtle grass. Widgeon grass occurs on Turkey Point Shoal. These grasses support diverse communities, providing essential habitat for juveniles of several economically important species of fish. Seagrasses are also particularly important in the diets of manatees and endangered sea turtles. They have diverse ecological functions, including improving water clarity, filtering pollutants from seawater, and nutrient cycling. In the northeastern Gulf of Mexico, where the FSUCML is located, seagrasses are mostly deciduous, dying back in winter and producing new leaves in spring. Damage to seagrass beds caused by propellers from motorboats is a major source of harm to this habitat, and may take several years to recover.
Offshore Reef
Along the edge of the West Florida continental shelf exists a broad band of limestone “drowned reefs” or “fossil reefs” at water depths ranging from approximately 50 m to over 120 m. These reefs are embedded in sand with a veneer of silt. The limestone is composed of numerous species of coral and algae and the remains of many sessile and encrusting benthic organisms, and has been dissolved and bored by clams and other organisms, leaving many holes and crannies of various sizes. It is covered with crustose coralline algae and sessile invertebrates, including encrusting sponges, sea fans, corkscrew sea whips, and scattered clusters of Oculina coral. Mobile invertebrates include arrow crabs, crinoids, hermit crabs, and basket stars. Fish on the reefs include amberjack, scamp, snowy grouper, red snapper, and many small reef fish, known as rough-tongued bass, which serve as forage species for the larger predators. These paleo reefs are important ecologically as areas of high biodiversity and as source areas supporting the spawning aggregations of the more economically important reef fish species of the southeastern United States. Yet virtually nothing is known of these ecosystems. Given the potential for human-induced threats to these habitats from fishing impact, oil and gas exploration and development, and water rediversion projects, the need is acute to identify and classify the area into spatially and temporally specific regions.
Sand DunesSand dunes occur along high-energy shorelines, extending from the beach to the inland forest. They are formed by the interaction of wind and “pioneer” plants that establish along the beach and help trap the sand. Plants that establish in the sand dunes, such as Sea Oatsa grass that lives in the fore zone--must be able to withstand harsh winds and salt spray. Their success is essential for maintaining the structural stability of the dunes. As sand is piled shoreward, it accumulates around roots of the pioneer plants, creating large mounds that protect the inner area from wind and salt spray. Winds push the dunes landward, where nutrients accumulate and different plants establish, while new foredunes are formed near the shore. This cycle reflects the formation of barrier islands, with dunes in different stages of succession supporting a large diversity of plant and insect species.Oyster Reefs
Oysters are animals that are protandrous hermaphrodites, meaning that they change sex over the course of their lifetime, starting out as males and, after two years, changing sex to become females. Oysters flourish in brackish waters where freshwater input is substantial. Their larvae prefer to settle on established oyster shell more than on any other type of substrate. Thus, they tend to use the older generations as a foundation for settlement and in so doing establish sometimes extensive oyster reefs, the interstices of which provide habitat for a multitude of species, including barnacles, crabs, mussels, snails, worms, and anemones. Along the Florida coast near the FSU Coastal and Marine Laboratory, oyster populations are fragmented and intertidal, forming ‘bars’ near river outflows. Farther west along the coast in Louisiana and Texas, oyster reefs can reach up to a kilometer in length.
Bogs
A bog is a type of freshwater wetland that is characterized by highly acidic soils and generally dominated by sphagnum moss. These conditions create a unique habitat where a number of highly specialized plants can be found, including bog buttons, blueberries, and a number of beautiful orchids. However, they are also ideal conditions for insectivorous plants such as sundews, bladderworts, butterworts, and pitcher plants. Bogs are important ecological areas for the rare species and high diversity that they support. Many bog communities are located in pine savannas in the Apalachicola National Forest, just a short drive from the FSU Coastal and Marine Laboratory. Click for more information on pitcher plant bogs.
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Contact: Florida State University · Coastal and Marine Laboratory 3618 Highway 98 St Teresa, FL 32358-2702 Phone: (850) 697-4120 FAX: (850) 697-3822 |
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