HYDROLOGICAL CHARACTERISTICS OF TAMPA BAY TRIBUTARIES 



171 



STATION 36 



5 20 000- R'VER DISCHARGES 



1^ 10,000- 

 o 



uj -' — — 



20.0-1 



PRECIPITATION  



..■..I. mill 



<0 

 UJ 



5 lO.oH 



z 



o-' 



30 0-, WATER TEMPERATURE 



°o 20.0 



10.0 



SALINITY 

 20.00^ 



o H 



0^ 10,00 - 



oJ 



20 On "^0"°'^'^'^ PO4 P 

 '°°jl fc E fe e E 



20.0 nJ°™" ''°''' 



10,0- 



D 0-^ 



d. 8.0- 



4 0- 

 



NO3 NO2 N 

 J ^ E ■= ^ L 



0.12 

 08- 

 004- 

 0- 



feh 



ONDJFMAMJ JASOND 

 1958 1959 



STATION 35 



.-■■.l.llllll.. 



« 1 E 



^ fe  fe 



f 



L 



 E 



ONDJFMAMJ JASOND 

 1958 1959 



SURFACE — I 

 BOTTOM 1 



F^OURE 6. — River discharge, precipitation, aud hydrological properties of Manatee River, Florida, October 19o8- 



December 1959. 



DISCUSSION 



Tlie annual temperature range of 15.0° to 30.5° 

 C. observed for Tampa Bay tributaries is com- 

 parable to rantjes of the shallow coastal subtropical 

 waters at Naples, Florida (Dragovich, 1961), and 

 to bay waters of Texas (Collier and Hedgpeth, 

 1950). Rapid changes in water temperature dur- 

 ing the winter are of considerable significance to 

 the resident biota. Sudden cold spells may result 

 in fish mortalities ( Springer and Woodburn, 1960) 

 or influence spawning and migrations in estuaries 

 (Collier and Hedgijeth, 1950). 



In general there was a rather good relation be- 

 tween monthly precipitation and river discharges. 



Only two river stations, 30 and 34, had fresh- 

 water salinity values (<0.5 Voo) throughout the 

 entire period of investigation. At the remaining 

 stations the siilinity levels ranged from oligohaline 

 (0.5 Vo„ to 5 Voo) and mesohaline (5 Voo to 18 

 Voo) to ix)lyhaline (18 Voo to 30 Voo). The in- 

 fluence of precipitation was obvious, particularly 

 at stations 29, 31, 32, 33, and 35. The salinity dis- 

 tribution at these stations indicated an alternation 

 between brackish- and fresh-water environments. 

 This condition pre.sents ecological barriers to some 

 organisms from both marine and fresh-water ends 

 of the estuary. In this regard G. hreve, the 

 Florida red-tide organism, was never found at 



