the best method developed was for a 

 biologist to fly with the Service pilot 

 over the area to be dusted about five min- 

 utes ahead of the dusting planes, and drop 

 a 15-minute smoke bomb in the center of the 

 area to be sprayed. 



Laboratory experiments (W. B. Wilson, 

 manuscript) showed that G. breve could be 

 effectively killed in 1 to 3 hours by 

 copper concentrations of 0.05 and 0.10 parts 

 per million, equivalent to 0.8 and 1.6 

 microgrcim atoms per liter. In making cal- 

 culations of the pounds of copper sulfate 

 per acre to use in dusting, if we assume 

 a depth of 10 feet then 20 pounds of CuSO^ 

 5H2O per acre will give 0.18 parts per 

 million of copper or 2.9 microgrcim atoms 

 per liter. 



Of course, the laboratory experiments 

 presuppose a uniformly mixed solution, so 

 that the junount used in the field needs to 

 be somewhat higher to allow for uneven 

 mixing. The copper content of water samples 

 taken soon after dusting showed that the 

 amount used was probably close to the mini- 

 mum effective dose, since the samples were 

 consistently lower than would be expected 

 from the calculations. Also, the average 

 depth of the water sprayed probably was 

 closer to 20 than to 10 feet. 



On the first day the dusting planes 

 attempted to use about 25 pounds per acre. 

 The immediate effect on the red tide organ- 

 isms was so drastic that we cut the amount 

 back to 20 pounds per acre, which was 

 thereafter maintained. 



NARRATIVE OF EXPERIMENTAL 

 CONTROL OPERATIONS 



On Thursday, September 26, dead fish 

 in small numbers were observed in the vicin- 

 ity of John's Pass and Madeira Beach, near 

 St. Petersburg, Florida (fig. 3, page 43). 

 The Florida State Board of Conservation and 

 the headquarters of the Gulf Fishery Inves- 

 tigations in Galveston were immediately 

 alerted. 



Counts of G. breve made on the 27th 

 from sajnples of water collected on the 26th 

 showed concentrations of fish killing pro- 

 portions. The staff of the Gulf Fishery 

 Investigations immediately distributed 7,200 

 pounds of copper sulfate, kept on hand for 



experimental purposes, in a small area of 

 high G. breve concentrations off Madeira 

 Beach, by dragging the material behind a 

 vessel in burlap sacks. Although the cop- 

 per sulfate was obviously effective in this 

 small area, it was at the same time apparent 

 that such slow distribution methods would 

 be inadequate for treating a major outbreak. 



After reviewing the situation (figs. 

 4 and 5, pages 44 and 45) on Saturday night, 

 the 28th, 20 tons of powdered copper sul- 

 fate were purchased. The material was 

 ordered early Sunday morning and at 3:30 

 p.m. the first loads of copper sulfate were 

 sprayed on the heavy concentrations of red 

 tide organisms noted off Blind Pass, by two 

 crop dusting planes hurriedly summoned from 

 Fort Myers. 



Before dusting commenced, the beaches 

 near Blind Pass showed rows of dead fish 

 and the airborne toxin from G. breve caused 

 coughing and choking among residents along 

 the beach. The spraying rapidly destroyed 

 the organisms as shown in figures 14 to 18 

 (pages 54-56). 



On Monday, September 30 (see fig. 6, 

 page 46), state officials pledged immediate 

 action to obtain release of funds to combat 

 the outbreak, since no federal funds were 

 available beyond those used on an emergency 

 basis from the research budget of the fed- 

 eral laboratory. The State of Florida 

 released $50,000 from the previously estab- 

 lished Red Tide Emergency Fund and the con- 

 trol experiment was continued. 



The Florida State Board of Conserva- 

 tion viorked closely with the Bureau of 

 Commercial Fisheries laboratory, not only 

 by furnishing necessary funds, but also the 

 vessel Punj ab for water sampling, the ves- 

 sel Mayan to distribute copper sulfate in 

 waters beyond the range of the planes (note 

 the two offshore areas off Tarpon Springs 

 in fig. 2, page 42), and conservation agents 

 with radio-equipped cars and walkie-talkies 

 for maintaining close contact between ves- 

 sels, scouting planes and the crop-dusting 

 planes. The U. S. Coast Guard Air Station 

 and the Coast Guard District Office cooper- 

 ated by furnishing helicopters from the air 

 station at St. Petersburg for spotting in- 

 fested areas, and dye packs and smoke bombs 

 used in marking the areas to be sprayed. 



Control operations were completely 



