Gunter (1952) reported, "In the summer 

 of 1935 a very heavy mortality of marine 

 fishes and other animals occurred in the 

 Gulf of Mexico and extended for a distance 

 of 250 miles from the Rio Grande northward. 

 A few fishes were killed in the lower bays 

 but practically all of the mortality was con- 

 fined to the Gulf. ..." In a later outbreak 

 in this area, Wilson and Ray (1956) identified 

 the causative organism as Gymnodinium breve . 



Semicircular surface structures were re- 

 ported by Ingle, Hutton, Shafer, ajnd Goss 

 (1959) to be comnnon features of the 1957 

 red-tide outbreak near the mouths of passes. 

 They said: "In every case observed by the 

 authors (R.M.I, and R.F.H.) the discolored 

 water, denoting a high concentration of dino- 

 flagellates, was found from the interface and 

 extending seaward." Ingle also stated (USFWS, 

 1958), "We made one trip along interphase and 

 found high concentrations as far as 15 miles 

 offshore. Very high counts as far as we could 

 go." 



Slobodkin (1953) based his hypothesis of 

 stable water masses wholly on theory. His 

 theory that organisms develop in a "discrete 

 mass of water of relatively low salinity" 

 differs from observations on blooms occurring 

 in streaks, the abrupt margins of the blooms, 

 and the formation of blooms at interfaces. 

 The theory does not explain howthe organisms, 

 floating in their lens of water, concentrate 

 high announts of nutrients from nutrient-poor 

 water. 



as a detoxicating agent in cultures of 

 Prymnesiunn parvum . 



Since Aldrich (1962) has established that 

 G. breve is autotrophic, it would seem that 

 there would necessarily be some delay before 

 the constituents of whole fish had had time 

 to recycle inorganic nutrients into the water. 



It should be noted that during the period 

 of time necessary for putrefaction, surface- 

 drifting fish may be blown far offshore, or 

 onto some beach, many miles from the red 

 water which killed them. Hela (1955) showed 

 that the drift of the dead fish can for practical 

 purposes be determined by wind observations 

 alone. Speaking of the 1947 outbreak, Anderson 

 (USFWS, 1958) said,". . . in that summer some 

 of the fish were pushed out, but that doesn't 

 mean that you don't have offshore kills. The 

 big concentrations were inshore. Fish that 

 were far offshore were in clear water. Most 

 fish found offshore were in a bad state of 

 decay, which nnade me think they had been 

 drifting for a long time after being killed 

 in red water." Wilson (USFWS, 1958), when 

 questioned, answered that in general fish 

 kills occur close to shore, except in certain 

 instances, and that he did not know of a bloom 

 completely offshore, not associated with aun 

 inshore bloom. In November 1954 during a 

 period of strong northeast winds, the Oregon 

 found dead fish 50 miles offshore. Finucane 

 (USFWS, 1958) said, ". . . In 1947 I don't 

 think they died near the Keys but were moved 

 down by wind action." 



Effect of Dead Fishes in Continuing a 

 Red-Tide Bloom 



The question of whether or not fish killed 

 by red tide aid in perpetuating or spreading 

 red tide is of some importance. Proponents 

 of such an hypothesis point out the immense 

 quantity of nutrients that can be made avail- 

 able by the decaying carcasses. 



Collier (1955) squeezed juices from freshly 

 killed fish into a culture he described as 

 about 3 million organisnns per quart; over- 

 night they tripled in number. Wilson (1955) 

 discovered, however, that if fish autolysate 

 is added to the original culture medium, 

 bacterial growth frequently is stimulated, 

 and the culture dies. For instance, when 

 added to a culture of 3 1/2 million per liter, 

 the organisms increased in 4 days to 9 1/2 

 million but then fell to zero in 1 week. 



In considering these results, it should be 

 noted that when fish are killed by red tide, 

 the fresh juices are not squeezed into the 

 water; the fish undergo a process of putrefac- 

 tion during which the bacteria nnust increase 

 enormously. In this regard Ray and Wilson 

 (1957) mentioned the effect of bacteria in 

 reducing the toxicity of G^. breve cultures, 

 and also mentioned the experiments of Shilo 

 and Aschner (1953) in which bacteria acted 



FIELD OBSERVATIONS ON FLORIDA 

 RED TIDE 



To aid in guiding our thinking, we compiled 

 table 1, showing the occurrence of recorded 

 outbreaks of red tide during the 117 years 

 from 1844 to I960. We found records of 20 

 toxic red tides, 3 in Texas and 17 on the 

 west coast of Florida, all of which can reason- 

 ably be attributed to blooms of Gymnodinium 

 breve . In evaluating these records, it should 

 be borne in mind that, especially in the earlier 

 reports, the observers did not separate cause 

 and effect. Reports of great quantities of 

 fish drifting ashore at Key West or on the Dry 

 Tortugas for instance, gave no indication of 

 the area or areas in which they were killed. 



Some of the recorded outbreaks may have 

 been minor. For instance, concerning the 1952 

 outbreak. Lackey and Hynes (1955) wrote, 

 "The 1952 outbreak was apparently rather 

 limited in the area affected, which seemed 

 to center around Sanibel Island. There is 

 little published information on this outbreak, 

 at least at the present time." Both Collier 

 (1954) and Chew (1953) confirmed the oc- 

 currence of this outbreak, however, placing 

 it around the Sanibel Island area in November. 



