SoliO'Ty %o 



Nove<N*r,1958 



Figure 37. Isohalines in Florida 

 Bay (adapted from 

 Lloyd 1964). 



not. Parameters most commonly re- 

 ported are salinity and temperature 

 (reported above) and turbidity 

 (Schmidt and Davis 1978). In upper 

 Florida Bay turbidity tends to be 

 highly variable, ranging from 1-3 

 mg/l after sustained winds of 10 to 

 20 knots (Scholl 1966). Toward the 

 Gulf of Mexico the winds are a less 

 influential but nontheless important 



factor in turbidity concentrations. 

 Here, however, the activities of 

 bottom feeders (especially mullet) 

 are commonly reported to cause 

 "whitings" (i.e., high turbidities) 

 as they feed in large schools on 

 grass beds and over the lime mud 

 sediments. 



5.7 FLORIDA KEYS 



The hydrologic cycle in the 

 Florida Keys involves a complex 

 array of transport mechanisms in- 

 cluding oceanic currents, evapora- 

 tive processes, tidal actions, 

 winds, freshwater flow, and cata- 

 strophic events such as hurricanes. 

 Of these, the tides, wind-driven 

 currents, and oceanic currents and 

 their associated spin-off eddies and 

 counter-currents, dominate the 



overall movement of water in the 

 system. 



Tides in the Florida Keys gen- 

 erally exhibit two high and two low 

 tides of uneven amplitude per tidal 

 day (or lunar day, 24.85 hrs), as 

 illustrated in Figure 38 (NOAA 

 1977). A semidiurnal tidal pattern 

 exists in the area north of Key 

 Largo while the mixed pattern occurs 

 to the south (Figure 39). The semi- 

 diurnal tidal pattern is similar to 

 the mixed, except the amplitudes of 

 the two highs and two lows are ap- 

 proximately equal. Also, as shown 

 in Table 16, the tidal range along 

 the shallow slope break (outer reef) 

 decreases from Fowey Rocks (ESE 

 of Miami) to Sand Key (SW of Key 

 West). 



Although a similar decrease 

 occurs nearshore, localized vari- 

 ables including winds, local bathy- 

 metry, and shoreline geomorphology 

 markedly affects the inshore tidal 

 amplitude and phase (Enos 1977, 

 Hanson 1980). Hanson (1980) obser- 

 ves a tidal phase shift of as much 

 as several hours between east (Bogie 



86 



