Table 1. — Occurrences of Florida red tide, 18^ to 1960 



No. 



General area 



Initial month Final month 



Months 

 unknown 



1- 

 2. 

 3. 



A. 

 5. 



6. 

 7. 



8. 

 9. 



10. 

 11. 

 12. 

 13. 

 14. 



15. 

 16. 



17. 



18. 

 19. 

 20. 



1844 



1854 



1856 or '57 



1865 



1878 



1879 



1880 



1882 



1883 



1884 



1885 



1908 



1916 



1935 



1946 



1947 



1947 



194e 



1952 



1953 



1953 



1954 



1954 



1955 



1955 



1957 



1959 



1960 



1960 



Tampa to Dry Tortugas 



Tampa to Key West 



Egmont Key 



Clearvirater to Egmont Key 



E^mont Key to Charlotte Harbor. 



Boca Grande to Big (faroo Pass.. 



South Texas 



Boca Grande and South 



Reached Tampa Bay in July 



South Texas 



Near Sanibel 



Tampa and South 



Venice and South 



South Texas 



Tampa and south 



Tampa to Venice 



£gmont Key 



E^ont Key 



■'■ n. 



Sept. (2). 



Aug. n. 



Oct. {'). 

 July ('). 



Oct. 



(^°). 



Oct. (8).... 

 June (^2,13). 

 Nov. (^')... 



Mar. 



Fall (")... 

 Nov. C-S,!'). 



Sept. (18,19) 



July (21). 



Sept. ("). 



Sept. (21). 



Sept. ("). 



Mar. ("). 



Juljr ("). 



Oct. 

 Nov. 



(^)... 

 (1)... 

 (^)... 



Dec. 



(^). 



Nov. (^)... 

 Aug. (12,") 



Jan. (',1') 

 Sept. ("). 



Jan.(i''i8,i') 

 Mar!""(20)!i! 



Feb. 

 Sept. 

 Deo. 

 Nov. 



Mar. 

 Aug. 



(21)... 

 (")... 

 (^^)... 

 (")... 

 (")... 



(^) 



(J) 

 (') 



{'> 

 (1,5) 



....... 



(8,9) 



•fli-)-- 



(«) 



"("*)" 



1 Ingersoll, 1882 



2 Jefferson et al., 1879 

 ^ Glazier, 1882 



' Jefferson, 1879 

 ' Moore, 1882 

 * Walker, 1884 

 ' Anon. , 1883 

 ' Taylor, 1917 



' Gunter, 1947 

 1° Glennan, 1887 



11 Canova, 1885 



12 Umd, 1935 

 1^ Burr, 1945 

 1" Gunter, 1952 

 1* Gunter et al., 

 1^ Galtsoff, 1948 



1948 



1' Univ. Miami, Mar. Lab., 1954 



18 Collier, 1954 



1' Chew, 1953 



2° Lackey and Hynes, 1955 



21 Finucane, 1964 



22 Wilson and Ray, 1956 

 2^ Finucane, 1960 



2* Finucane, 1961 



Seasonal Occurrence of Red Tide 



Table 2 (from data of table 1) shows the 

 seasonal occurrence of red tides in Florida 

 for the eight outbreaks for which the data 

 appear to be reasonably accurate as to month. 

 Several features are of interest. All outbreaks 

 commenced between August and November, 

 and half started in Septennber. Six of the out- 

 breaks ended between November and Febru- 

 ary, suggesting the effect of lowered tem- 

 perature in controlling growthof the organism. 

 At least three of the outbreaks apparently 

 did not cease during winter aind spring, but 

 merely continued at a slow pace until more 

 temperate weather returned. 



Another interesting feature of table 2 is 

 that of 48 months in which toxic blooms 

 were present, only 11 occurred during the 

 6-nnonth period from February through July. 

 This coincides with the observations and 

 opinions of several authors that most dino- 

 flagellates bloom after the diatom flowering 

 and after the nutrients have become rela- 

 tively scarce. It also coincides with the data 



on temperature, nnentioned previously, which 

 indicate that G. breve cam thrive at tenn. 

 peratures from 16° to 27° C. This seasonal 

 blooming in early autumn, however, could 

 also be encouraged by seasonal rainfall, which 

 is normally much higher in June, July, August, 

 and September than in other months. 



The Role of Convergences in Causing 

 Red-Tide Blooms 



Several cogent arguments support the hy- 

 pothesis that convergences play an important 

 role in initiating cind maintaining toxic con- 

 centrations of the Florida red tide. Some of 

 these arguments are: 



1. The Florida red tide apparently can 

 aggregate in fish-killing concentrations at 

 a very low nutrient level; however, the phos- 

 phorus values within such concentrations (in- 

 cluding the organisms in the samples) are 

 often high- -often far too high to be accounted 

 for without supposing the organisms to be 

 capable of concentrating practically all of 

 the phosphorus available in the water column. 



