Hydrology of Tampa Bay and Adjacent Waters 

 Alexander Dragovich and Billie Z. May 



Observations consisted of temperature (1, 136 observations), sa- 

 linity (1, 137), total phosphate-phosphorus (1, 103), nitrate-nitrite nitrogen 

 (1, 089), ammonia (195), total organic and inorganic nitrogen (333), silicon 

 (1, 080), calcium (1, 077), and total alkalinity (1, 077). 



Samples were collected monthly from 25 stations from Tampa Bay 

 to 40 miles offshore with 2 additional stations 50 and 60 miles offshore during 

 the summer and fall months. 



Temperature The maximum water temperature (31. 6° C. ) was recorded 



during July in Egmont Channel and the minimum (12. 3° C. ) during December 

 in lower Tampa Bay. Owing to the shallowness of Tampa Bay and the waters 



up to 5 miles offshore, heat exchange 

 is rapid and equilibrium between the 

 water and air is readily attained. 



Comparisons of G. breve 

 incidence with water temperatures 

 yielded results similar to those given 

 in last year's report. The distribution 

 of G. breve seems to be restricted by 

 temperature minima rather than max- 

 ima. G. breve was absent at temper- 

 atures below 14. 2" C. which occurred 

 in December and present at 31.3° C. 

 in July. 



G. breve was absent from 

 Tampa Bay during the months with 

 lowest temperatures. The organism's 

 simultaneous presence in the farther 

 offshore waters continues to suggest 

 that the warmer neritic waters may 

 be important to the winter survival 

 Measuring light intensity of G. breve, 



with a photocell. 



Salinity Salinity varied because of precipitation and stream discharges. 



During most of the year precipitation was below normal or near to the long- 

 term means. Extremely heavy rainfalls were associated with hurricane 

 "Brenda" (July 28 and 29). According to the reported rainfall, hurricane 

 "Donna" (September 9- 11), which swept through the general Tampa Bay drain- 

 age basin, was not a particularily wet hurricane. An exceptionally dry period 

 was recorded during November. This year's salinities were higher than last 

 year's. 



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