ABSTRACT 



The first large-scale attempt at controlling 

 the red tide was made in the autumn of 1957. About 16 

 square miles stretching along 32 miles of shoreline from 

 Anclote Key to Pass-a-grille Beach, off St. Petersburg, 

 Florida, were dusted with copper sulfate (CuS04-5H20) at 

 about 20 pounds to the acre by crop-dusting planes. The 

 copper very quickly reduced Gymnodinium breve , the red 

 tide organisms, from several million to practically none 

 per liter relieving the area of the respiratory irrita- 

 tion caused by the airborne toxin of G. breve . In 2 out 

 5 areas the organisms rose again to concentrations lethal 

 to fish in 10 to 14 days after dusting. This method is 

 not recommended for general control, but will give tem- 

 porary relief in local situations from the airborne 

 toxin. 



