environment for early life stages. Saltmarshes are also a fundamental 
part of nutrient cycles, long-term accumulators of pollution, short-term 
pollution buffers, and inhibitors of erosion. 
Seagrass Meadows cover approximately 12,968 ha, or 10% of the bay 
system. They are the dominant vegetative cover in the bay and are 
critically important to productivity of the bay system. Seagrass meadows 
provide a direct food source to herbivores, such as sea turtles and 
manatees, and to numerous detritivores. Because this habitat is subtidal 
and extensive in distribution, it provides a constant and expansive 
structural shelter for fish, shellfish, and crustaceans important to the 
fishery. In addition, the complex food web and tremendous organism 
diversity and quantity provide a major food source to all stages of 
fishery species in the bay. Seagrass meadows also stabilize sediments 
and prevent erosion. They improve water quality by removing nutrients 
and by providing a baffle effect on waves and currents, which causes 
settling of suspended particulates in the water column. Macroalgae, in 
either drift or attached forms, are often associated with seagrass 
meadows and other communities of the estuary. The algae are a more 
readily digestible food source than seagrass and appear to be important 
to the ecology of the estuary. 
Mudfl ats (sandbars, sandflats, flats) cover approximately 
9,389 ha, or 8% of the bay bottom. They are "unvegetated" sites that 
become exposed at low tide. During the day they serve as primary feeding 
grounds for wading and shore birds. At night, fish, crabs, and shrimp 
become major consumers. Production in a mudflat is driven by smaller 
algae, such as dinoflagel1ates, diatoms, and blue-greens; macrophytic 
algae have a lesser role. Flats do not provide a protective structural 
component except to burrowers. A special type of flat found in Tampa Bay 
is the saltbarren (saltern), a transitional area between mangrove- 
saltmarsh and uplands. Although a harsh habitat, saltbarrens are 
important for bird populations, and growing evidence exists that they 
support fisheries species during irregular flooding. Saltbarrens host a 
variety of vegetation from stressed mangroves to lush succulents. 
Unvegetated subtidal bottom comprises 92,334 ha, or 74% of the 
estuary. For this discussion, this area also includes artificial reefs, 
natural rock reefs, algal communities, sand, mud, and others. This 
habitat type is a major component of the system, as in most estuaries, 
and although extremely important for overall bay production, its extent 
serves to emphasize the importance of the relatively lesser amounts of 
structural, vegetative cover on the periphery of the bay. 
Depending on the tides, the water column , overlies part or all of 
the estuarine habitat. The chemical, physical, and biological 
composition of the water column influences all aspects of the estuary. 
Phytoplankton are the primary producers and not limited to shallow areas 
or shorelines (as are seagrasses, mangroves, and saltmarshes). 
Phytoplankton exist as readily digestible food for consumers and are 
essential components in the food chain that supports larval stages of the 
fishery. An abnormal abundance of phytoplankton occurs in the Tampa Bay 
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