a' 



n 



44 SO SI SS 40 SI S& 46 42 41 SB S4 48 49 S7 4] SJ 4S 47 60 S9 



Figure 4.~Red-tIde years in relation to phosphorus 

 intrusion into Tampa Bay and Charlotte Harbor due to 

 river discharge, March-September, 1940-60. 



much discussion of the means by which the 

 dinoflagellates concentrate the nutrients with- 

 in the water column in order to bloom in 

 relatively impoverished waters. One important 

 question is why do they not bloom earlier in 

 the year when nutrient levels are at their 

 maxima. 



Several authors have reasoned that the 

 dinoflagellates may depend upon preceding 

 organisms to concentrate the nutrients. Thus, 

 Graham et al. (1954) stressed the ability 

 of the dense wind-blown blooms of Skujaella 

 to concentrate phosphorus. The theory is that 

 when the preceding bloom dies, the phosphorus 

 that is released will be concentrated in a 

 small area. This theory does not explain 

 the ability of the dinoflagellates to bloom 

 in nutrient -poor water, nor their apparent 

 failure to bloom earlier while nutrients are 

 more abundant. 



There appear to be two schools of thought 

 on this subject. One idea is that the preceding 

 blooms of diatoms may reduce one or more 

 of the inorganic nutrients to a level favorable 

 for dinoflagellates. The second idea sug- 

 gests that the first group of organisms pro- 

 duces external metabolites that inhibit growth 

 of competing organisms, but which may benefit 

 succeeding populations (Lucas, 1947, 1949; 

 Rice, 1954). 



Distribution of Red-Tide Blooms 



It is very important to an under stamding 

 of red-tide blooms to consider how concentra- 

 tions of the organism are distributed in space. 

 Despite wild statements of dense red tide 

 over "hundreds of square miles," it is ob- 

 vious from the many reports by trained 

 observers that nothing could be much further 

 from the truth. In fact, all but a few authors 

 agree that red-tide blooms occur in streaks. 



Reporting on an outbreak of Gonyaulax 

 catanella in California, Bonnot and Phillips 

 (1938) stated, ". . . It was not distributed 

 uniformly throughout the above region but 

 appeared in streaks and patches. It was first 

 noted in Monterey Bay about August 11, ap- 

 pearing as a streak paralleling shore. This 

 streak was about 100 yards wide and com- 

 menced approximately 200 feet offshore. Later 

 this was scattered over a wider area, ap- 

 parently by tide smd wind. Other streaks and 

 patches appeared farther offshore. . . ." 

 Torrey (1902) gave a similar report, stating 

 that a bloom of Gonyaulaix was first noted as a 

 red streak off the mouth of San Pedro Harbor, 

 and adding that, "The boundaries of the red 

 streaks were quite sharply marked, although the 

 water between streaks often contained Gon- 

 yaulax in abundance. . . ." Whitelegge (1891) 

 wrote that a heavy bloom of Glenodinium rub- 

 rum occurred in streaks or patches at Port 

 Jackson, Australia. 



A Delaware Bay bloom of Amphidiniurr. 

 fusiforme and Gymnodinium splendens was 

 described by Pomeroy et al. (1956), ". . . the 

 blooms were typically in the form of elongated 

 slicks with abrupt margins. This wasalsotrue 

 in the 1952 bloom. . . ." 



Concerning the Florida red tide. Walker 

 (1884) stated, ". . , the poisoned water was 

 not diffused generally, but ran in streams 

 of various sizes, as proven by fish dying in 

 vast numbers instantly upon reaching such 

 localities." He also quoted from fishermen 

 who transported fish in live wells in their 

 vessels, "The poisoned water runs in streaks, 

 for often when three or four smacks are in 

 company one or two will lose all their fish 

 in a few minutes, while the others, a short 

 distance off, lose none." Describing the 1916 

 outbreak, Taylor (1917b) said, ". . . This 

 colored water was described as being not 

 uniformly distributed, but occurring in streaks, 

 and it was in these streaks that the fish 

 are said to have perished. . . ." 



Finucane (1964) stated, ". . . Since its inci- 

 dence during nonbloom periods is primarily 

 confined to offshore waters, the organism prob- 

 ably is more neritic than estuarine. G. breve 

 occurred in approximately equal frequency in 

 both estuarine and neritic waters only during the 

 red-tide outbreaks in 1954 and 1957. . . ." 



