HYDROLOGICAL AND BIOLOGICAL CHARACTERISTICS OF FLORIDA'S 



WEST COAST TRIBUTARIES' 



BY Alexander Dragovich,= John A. Kelly. Jr.,' and H. Grant Goodell* 



ABSTRACT 



Data are given for 10 stations in the Hillsborough, 

 Alafia, Little Manatee, Manatee, Myakka, Peace, and 

 Caloosahatchee Rivers, which flow into west Florida 

 bays. Variations in temperature, salinity, chlorophyll 

 "a," dissolved oxygen, total phosphorus, inorganic 

 phosphate-phosphorus, copper, and iron were recorded 

 over a 13-month period. The variations are discussed in 

 terms of differences in precipitation, river discharges, 

 and general geological properties of river basins. Certain 

 hydrological conditions of the tributaries are compared 

 with the conditions of the adjacent neritic waters of the 

 Gulf of Mexico. 



Thermal diSerences between surface and bottom were 

 negHgible. The temporal distribution of salinity was 

 influenced by precipitation. Distribution of total phos- 



phorus and inorganic phosphate-phosphorus was re- 

 lated to the underlying phosphatic formations of the 

 various river basins. Maximum values of total dissolved 

 oxygen occurred in winter and minimum in summer; 

 no anaerobic conditions were encountered. Concentra- 

 tions of chlorophyll "a," copper, and iron were higher in 

 the rivers than in the adjacent sea. 



The quantity of nutrients contributed by rivers to the 

 sea is determined largely by the volume of river flow, 

 not by the actual concentrations of the nutrients. The 

 possible relation between the mean input of various 

 materials by the tributaries, and the presence of the 

 Florida red-tide organism, Gymnodinium breve Davis, 

 was tested. A correlation between iron and G. breve 

 was significant at the 80-percent level. 



Ecological studies were made of the waters of 

 Tampa Bay, Charlotte Harbor, and the adjacent 

 Gulf of Mexico as part of an investigation of the 

 Florida red-tide organism, Gymnodinium breve. 

 Red tide in waters along the southwest Florida 

 coast is associated with dense concentrations of 

 G. breve, discolored water, and fish kills. 



Red tides throughout the world occur primarily 

 in coastal areas and usually in periods of heavy 

 rainfall and increased river discharge. The i)resence 

 and growth of phytoplankton in coastal waters 

 depend largely on the quantity and quality of 

 inorganic and organic nutrients, particularly 

 trace metals and external metabolites (Provasoli, 

 1958). 



' Contribution No. 40, Bureau of Commercial Fisheries Biological Labora- 

 tory, St. Petersburg Beach, Fla. 33706. 



= Alexander Dragovich, Fishery Biologist, did this research at the Bureau 

 of Commercial Fisheries Biological Laborator^•, St. Petersburg Beach, Fla. 

 33706. His present address is: Bureau of Commercial Fisheries Tropical 

 Atlantic Biological Laboratory, Miami, Fla. 33149. 



'John A. Kelly, Jr., Fishery Biologist, Bureau of Commercial Fisheries 

 Biological Laboratory, St. Petersburg Beach, Fla. 33706. 



' H. Grant Goodell, Associate Professor, Department of Geolog>-, Florida 

 State University, Tallahassee, Fla. 32306. 



Rivers make annual additions of nutrients to the 

 sea. In evaluating the effects of Florida west coast 

 tributaries on red-tide outbreaks and estuarine 

 productivity, a thorough knowledge of the hydrol- 

 ogy of the tributaries may be helpful. Because 

 published information on the hydrology of these 

 streams is limited, a survey was undertaken to 

 assess hydrological characteristics of seven major 

 rivers that flow into Gulf estuaries. Dragovich 

 and May (1962) listed publications concerned 

 with the hydrolog>^ of streams of the west coast 

 of Florida. 



We studied monthly variations in certain 

 hydrological and biological properties of the 

 Myakka, Peace, and Caloosahatchee Rivers which 

 enter the Charlotte Harbor estuarine system. 

 These streams were selected because of their 

 importance to red-tide problems and coastal 

 oceanography. The Hillsborough, Alafia, Little 

 Manatee, and Manatee Rivers, which are tribu- 

 taries of Tampa Bay, were included because new 

 ecological factors were added to those measured 



PubUshed March 1968. 

 FISHERY bulletin: VOLUME 66, NO. 3 



463 



