LARGE-SCALE EXPERIMENTAL TEST OF CXDPPER SULFATE AS A CONTROL 

 FOR THE FLORIDA RED TIDE 



Laboratory experiments, and a few 

 field experiments (Joe 0. Bell, unpublished 

 manuscript), have indicated that the red 

 tide organism, Gymnodinium breve , is easily 

 killed by fairly low concentrations of 

 copper ions. Because of the relatively low 

 cost of copper sulfate crystals ($215 a ton, 

 delivered) it was felt that copper sulfate, 

 if it could be properly applied, might prove 

 to be useful as a control agent. 



Accordingly, when the red tide out- 

 break of 1957 started offshore from St. 

 Petersburg, Florida, it was decided to make 

 the first large-scale attempt to determine 

 the feasibility of control (table 1, page 

 5; figs. 1 and 2, pages 41 and 42). The 

 feasibility was to be gauged by: 



1. Cost of control for the area 

 covered. 



2. Duration of control. 



3. Whether any apparent damage to 

 other organisms occurred. 



NOTE. — This large-scale attempt at control 

 was participated in by all members of the 

 Gulf Fishery Investigations working on red 

 tide. William B. Wilson, and Drs. Sammy 

 M. Ray and David V. Aldrich from the Gal- 

 veston Laboratory made the counts of G. 

 breve in the sea-water samples, assisted by 

 Dr. McKinley Jambor and Jean Gates. John 

 Finucane made cui aerial reconnaisance each 

 day and developed the final dusting tech- 

 nique. Alexander Dragovich made the vessel 

 surveys and collected the samples for both 

 copper analysis and G. breve counts. Espe- 

 cial credit should also be given pilot 

 William D. (Tommy) Wood who flew the Ser- 

 vice plane and Captain John D. McCormick 

 who operated the vessel Kingf ish regardless 

 of weather. As indicated in the text, the 

 Florida State Board of Conservation took 

 £in active and vigorous part, and special 

 thanks due Ernest C. Mitts, Director; Robert 

 M. Ingle, Director of Research; and Dr. 

 Robert F. Hutton, in charge of their St. 

 Petersburg Laboratory. 



As far as the third criterion is 

 concerned but little information was 

 obtained, but more concerning the effect 

 of copper on other organisms under actual 

 field conditions is being gathered in 

 another experiment. 



The incidence of red tide and the 

 density of the organisms, before, during, 

 and after the experiment, were gauged by 

 aerial and vessel observation of dead fish 

 and discolored water, and, more accurately, 

 by consistent laboratory counts of the 

 organisms from water samples collected 

 through the period. The detailed data are 

 contained in tables 2 to 4 (pages 6 - 24). 



Despite the emergency nature of the 

 operation numerous water samples were col- 

 lected for copper Einalysis throughout the 

 period (tables4 and 5, pages 24 and 40). 



DUSTING METHODS 



Since there was no previous experi- 

 ence of large-scale dusting over water 

 areas without discrete boundaries it was 

 necessary to improvise and develop methods 

 as the work proceeded. On land the crop- 

 dusting planes can follow rows of plantings 

 or fly straight toward a definite object, 

 and the end of the field or area is usually 

 clearly defined. 



Our first attempt to provide a teirget 

 and line of flight for the dusting planes 

 consisted in having the planes dust between 

 a large orange target on the beach ctnd the 

 laboratory vessel Kingf ish , which main- 

 tained by radar a stable position just 

 offshore of the area of discolored water. 

 After each plane locid the vessel and target 

 were moved forward. 



This method was abandoned because 

 (1) it tied up the vessel, which was needed 

 for sampling, (2) it was difficult to use 

 the beach target except on straight 

 stretches of beach, and (3) many dense 

 patches of discolored water were somewhat 

 offshore, and did not require dusting close 

 to the beach. After some experimentation 



