HYDROLOGICAL CHARACTERISTICS OF TAMPA BAY TRIBUTARIES 



By Alexander Dragovich, Fishery Research Biologist, and 



BiLLiE Z. May, Analytical Chemist 



BUREAU OF COMMERCIAL FISHERIES 



This investigation is part of a study of Tampa 

 Bay and adjacent neritic waters in connection with 

 an effort to control the Florida red-tide menace. 

 The Florida red tide is a natural fish-killing 

 phenomenon in the waters along southwest Florida 

 coast and is always associated with discolored 

 water containing dense populations of Gyni- 

 nodinvwm hreve, a naked dinoflagellate. The pri- 

 mary objective was the collection of sufficient 

 data to observe the natural levels and seasonal 

 fluctuations of salinity, total phosphorus, inor- 

 ganic phosphate, nitrate-nitrite nitrogen, and total 

 dissolved copper in the Hillsborough, Alafia, 

 Little Manatee, and Manatee Rivers which flow 

 into Tampa Bay. Copper was included in this 

 hydrological survey because of its high toxicity to 

 laboratory cultures of Gymnodinlmn breve. 

 Thus, copper was of particular interest as a pos- 

 sible limiting factor in the growth of G. breve in 

 its natural surroundings. A secondary objective 

 was to observe the influences of precipitation and 

 the geological formations miderlying the area 

 upon the chemical composition of these rivers. 



The chemical composition of the rivers has an 

 important bearing on general problems of coastal 

 oceanography (Ketchum, Redfield, and Ayers, 

 1951). Furthermore, it is essential that the 

 chemical composition of tlie river watei-s be known 

 for proper evaluation of the relative importance 

 of the Tampa Bay area to red-tide research and 

 other estuarine studies (Rochford, 1951; Spencer, 

 1956 ; and Manache, 1958) . Although the chemi- 

 cal composition of some Florida rivers has been 

 studied previously by the U.S. Fish and Wild- 

 life Service (Graham, Ami.son, and Marvin, 1954; 

 Finucane and Dragovich, 1959; Dragovich and 

 others, 19fil) ; Geological Survey, Branch of Sur- 

 face Waters, TTniversity of Florida (Specht, 



Approved for publication, July 28, 1961. Fishery Bulletin 205. 



1950) ; and by the Florida Geological Survey 

 (Odum, 1953), little hydrological information has 

 been gathered for the rivers flowing into Tampa 

 Bay. 



The authors are indebted to William B. Wil- 

 son for numerous valuable suggestions during this 

 study. Jolm A. Kelly, Jr., and John H. Finu- 

 cane provided technical assistance. 



MATERIALS AND METHODS 



From October 1, 1958, through December 31, 

 1959, monthly collections of surface and bottom 

 waters were made at eight stations ( fig. 1 ) . Sam- 

 ples for all analyses were taken with a weighted 

 polyethylene container. Samples for total phos- 

 phate-phosphorus, inorganic phosphate-phos- 

 phorus, and nitrate-nitrite nitrogen were imme- 

 diately transferred from the containers into 

 200-mm. culture vials which were capped with 

 polyethylene-lined screw caps and quickly frozen. 

 Samples for the determination of copper and 

 salinity were transferred into 250-ml. glass-stop- 

 pered bottles, and those for salinity into 4-oz. 

 prescription bottles. All containers used for 

 sampling were chemically cleaned prior to use. 



The following methods of analysis were 

 employed : 



Water temi>eratiire : t'eiitigrade llieniuniieter graduatini 

 in tenths of a degree. 



Salinity: Mohr-Knudsen method (Knudsen, 1901). 



Total phosphate-phosphorus: Harvey (1948) method. 



Inorganic phosphate-phosphorus : Robinson and Thomp- 

 son (1948) method. 



Nitrate-nitrite nitrogen: Zwicker and Robinson (1944) 

 method as modified by Marvin ( 19.")")). 



Copper: Hoste, Eeckhout, and Gillis (1953) method. 



Samples taken for oopijer analyses were filtered. Sam- 

 ples coUeeted for phosphorus and nitrogen determinations 

 were not filtered. 



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