Figure 1 .--North-South areas used In coding Florida red- tide data. 



HISTORICAL 



Red tide with its concomitant mass nnortali- 

 ties is not a phenomenon peculiar to Florida. 

 Overblooming of plankton organisms has been 

 well known since ancient times. It should 

 suffice to note that discolored water has been 

 observed in widely scattered seas; the Red 

 Sea and the Gulf of California (once nanned 

 the Vermilion Sea) are cases in point. Many 

 discolorations are apparently harmless, or at 

 least caused by nontoxic organisms, such as 



the tremendous bloonns of the diatom Axila- 

 codiscus kittoni at Copalis Beach, Wash. A 

 few discolorations arise from swarms of 

 copepods, from ciliates, or from chromogenic 

 bacteria, but the great majority are caused 

 by dinoflagellates, some of which are appar- 

 ently only slightly toxic, if at all. They vary 

 in color from almost transparent, through 

 pale green and yellow, to amber and bright 

 red. Many are luminescent; some have a 

 definite cuticle (are armored), and many are 

 naked. In some localities the overblooming 



