designated by the state as Outstanding Florida Waters, which provides for 
strict limits to degradation (Florida Department of Environmental 
Regulation 1986). Incomplete nutrient and other data suggest a general 
trend of improvement and a decline in salinity which has been most 
evident along the mainland shore. Urban stormwater runoff has been 
implicated as the cause for reduced salinities (Heyl and Dixon 1988). 
Areas of "fair" water quality include the bayside waters of Longboat Key, 
Little Sarasota Bay, and Phillippi Creek. Whitaker Bayou has fair to 
"poor" water quality because of stormwater and the City of Sarasota’s 
municipal wastewater treatment plant effluent. An area of about 210 
acres in the bay is directly affected by Whitaker Bayou discharges 
(Figure 2), and the area of indirect effects is probably ten times larger 
(Pierce and Brown 1986, Fortune 1985). 
Direct and indirect effects of dredging and filling have not been 
evaluated with respect to water quality but are considered serious. Some 
beaches on all islands have been nourished at least once. Longboat and 
New Passes have been dredged for navigation purposes. The Intracoastal 
Waterway definitely caused several areas of bay-bottom to be spoiled; may 
be responsible for large losses of seagrasses in the north bay due to 
indirect turbidity effects; and is believed to have caused or enhanced 
closure of Midnight Pass (in Little Sarasota Bay, between Siesta and 
Casey Keys) (Sarasota County 1984). Major residential and commercial 
filling projects have been conducted on Bird, Lido, and Longboat Keys and 
City Island. These combined projects have altered circulation, tidal 
prisms, fine sediment budgets, inlet stability, bay transparency, and 
other parameters. 
The primary producers of Sarasota Bay are phytoplankton, 
seagrasses, macroalgae, and wetlands (marshes and mangrove forests). The 
system is converting from a phytoplankton-dominated one with significant 
contributions (of carbon fixation, habitat, etc.) by the other producers, 
to a more simplified system dominated by phytoplankton without these 
other producers (Steidinger and Phillips 1988; Lewis 1988; Evans and 
Evans 1988). Sarasota Bay and nearby waters are regularly affected by 
naturally occurring dinoflagellate blooms known as red tides. These 
blooms originate far offshore but may be perpetuated by inshore nutrient 
enrichment. Red tides defaunate affected areas of the bay and inhibit 
tourism (Habas and Gilbert 1974). During summer months local 
phytoplankton blooms also kill fish in canals. 
There are four seagrass species in the bay; all grow in water less 
than 6-7 ft deep. Between 1948 and 1979 there was a 54% decrease in 
seagrass cover along the eastern bay; a 65% loss around New Pass; and an 
83% loss around Whitaker Bayou (Sauers and Patten 1981). Baywide losses 
are estimated to be 20-30 percent (Figures 3 and 4) (Steidinger and 
Phillips 1988). Causes of these losses are not definitely known, but 
mineral turbidity (from beach, inlet and ICW dredging) and organic 
turbidity (from STP effluents) are suspected. Marshes are naturally rare 
in the bay, but three species of mangroves grow along protected 
intertidal shorelines instead. Forests have been ditched for mosquito 
control and filled for upland development. Bay shorelines have been 
189 
