planned carefully because several lines of 

 endeavor appeared practical. For example, the 

 characteristics of the toxin from G. breve had 

 never been determined, even though its fish- 

 killing capacity had been well known for sev- 

 eral years. Investigation of the toxin could 

 improve the possibilities of controlling the 

 effects of red tide. 



After several approaches were considered, 

 the principal program was designed to include 

 a long-term, systematic study of plankton 

 succession in two estuaries, Tampa Bay and 

 Charlotte Harbor, and along offshore transects 

 between the two areas. The purposes were to 

 explore the year-round interrelation of plank- 

 tonic species and to determine the reaction of 

 these species to the environment and to related 

 organisms during different seasons. Monthly 

 collections began February 1964. 



In addition to the field studies, we were 

 concerned with the further examination of 

 past red-tide data that had received only 

 cursory analysis. We felt we could add greatly 

 to the knowledge of G. breve and its relation 

 to hydrography by automatic data computa- 

 tion; also, some of the factors previously 

 measured nnight prove to have no significant 

 effect on the growth, survival, and multiplica- 

 tion of the organism. With these possibilities 

 in nnind, the data are now being programmed 

 for computation to test the dependence of 

 G. breve on single and multiple environmental 

 factors. 



Funds were awarded also by contract to the 

 University of Alabama for the assinnilation 

 and interpretation of red-tide literature. This 

 work resulted in the completion of an anno- 



tated and interpretive bibliography in May 

 1964, to be used by participants in this Sym- 

 posium and in future red-tide research. The 

 bibliography is expected to be published at a 

 later date. It includes references to research 

 on red tide and related subjects by Federal, 

 State, institutional, and individual researchers. 



This Synnposium represents the third seg- 

 nnent in the use of red-tide funds in Fiscal 

 Year 1965 and the first phase of a renewed 

 approach to the problem. It had become clear 

 that coordination should be established in 

 planning and conducting red-tide research, and 

 that definite and precise goals should be sought 

 in further attacks on this complex problem. 



Participants were chosen to represent the 

 several disciplines usually concerned with 

 red-tide research: microbiology, fishery 

 biology, and oceanography. The purpose was 

 to discuss research already completed by 

 several agencies investigating the red-tide 

 problem and to explore the direction which 

 research should follow in the future. Agencies 

 represented were: Bureau of Sport Fisheries 

 and Wildlife and Bureau of Commercial Fish- 

 eries of the U.S. Fish and Wildlife Service; 

 Florida Board of Conservation; Gulf Coast 

 Research Laboratory (Mississippi); U.S. De- 

 partment of the Navy; St. Petersburg Junior 

 College; Institute of Marine Science (Miami); 

 Oceanographic Institute of Florida State Uni- 

 versity; Florida Atlantic University; U.S. Army 

 Biological Laboratory; Haskins Laboratories 

 (New York); Florida Presbyterian College; 

 University of Alabama; Gulf Coast Shellfish 

 Sanitation Research Center; and California 

 State Fishery Laboratory. 



ABSTRACTS OF DISCUSSIO>JS 



During the first 2 days of the Symposium, 

 opinions were expressed by participants and 

 discussed to establish guidelines and design 

 further research. Comments that were re- 

 corded and transcribed are abstracted in the 

 following sections of this report. 



ROLE OF VARIOUS FACTORS CAUSING 



RED-TIDE BLOOMS AS DEDUCED 



FROM FIELD OBSERVATIONS 



By George A. Rounsefell 

 University of Alabama, University, Ala. 



Over a 50-year period, the occurrence of 

 fish-killing red tides in western Florida has 

 been favored by heavy rainfall from March to 

 Septennber. Blooms in some years when pre- 

 cipitation was not heavy indicate that this is 

 only one of the associated factors. 



Analysis of extensive data collected in 1 954- 

 61 showed that G. breve was abundant in a 



narrow strip along the coast. The organism 

 is definitely neritic, seldom penetrating far 

 into bays. 



The upper limit of water temperature for 

 blooms appears to lie between 28° and 30° C. 

 The organisnns were not taken below 10° C; 

 abundance begins to decrease at about 15° C. 

 The upper limit of temperature is normally 

 exceeded in midsummer; this may limit sum- 

 mer abundance. Lower and upper limits of 

 abundance are at about 24% and 34 /'„ salinity. 

 Salinity range for fish- killing concentrations 

 is about 30%, to 34%„, but the lower limit of the 

 range is not well defined. Reduced precipita- 

 tion during the summer usually results in 

 salinity too high for blooms of G. breve. 



Winds were heaviest during the spring and 

 early sunnmer, when red tide seldonn blooms, 

 and least in August, Septennber, and October, 

 when bloonns often occurred. A high number 

 of hours of wind appears to have a definitely 

 limiting effect on the abundance of G. breve . 

 An analysis of phosphorus and G. breve abun- 

 dance for both red-tide and non- red-tide 



