when the upwelling of cold water is 

 at a minimum and water temperatures 

 are the highest of the year (Brongersma- 

 Sanders, 1948). ... [p. 401.] 



two such adjoining cells. Under these 

 conditions parallel streaks of floating 

 matter are produced (Fig. 5). (For a 

 more detailed description of this proc- 

 ess, see Langmuir, 1938; Stommel, 

 1949). [p. 406-407.] 



". . . there may be insufficient nutri- 

 ents normally present in sea water, 

 and no known mechanism for concen- 

 trating them to a sufficiently high level, 

 to support the development of a typical 

 red tide. The remaining possibility, 

 that the organisms themselves become 

 concentrated after growth, will be dis- 

 cussed below." [p. 403.] 



The author here discussed at length, 

 with much controversial documentation, 

 the vertical migration of dinoflagellates 

 and how light and buoyancy can affect 

 it. His evidence for surface concentra- 

 tion is sketchy (for only two species 

 in 6 m. of water). He said the accumu- 

 lation of buoyant organisms at the 

 surface would be enhanced in the ab- 

 sence of vertical mixing of the water, 

 and that most occurrences of red tide 

 throughout the world were accompanied 

 or preceded by periods of calm weather 

 and smooth seas. He added that such 

 conditions, together with the high tem- 

 peratures which usually accompany 

 them, may cause thermal stratification, 

 giving additional resistance to vertical 

 mixing. 



Ryther suggested three means by 

 which organisms accumulated at the 

 surface of the water nnay be further 

 concentrated: 



"(1) Prevailing onshore winds: Sur- 

 face water driven shoreward by pre- 

 vailing onshore winds establishes a 

 circular pattern, sinking at the waters 

 edge and returning seaward at lower 

 depths. Buoyant organisms will ac- 

 cumulate in windrows along shore or 

 at the region of descent (Fig. 3). 



"(2) Where brackish coastal water, 

 particularly in the vicinity of river 

 mouths, meets open ocean water, there 

 is a mixing and sinking of the two water 

 masses along a line of convergence. 

 Both types of water flow toward this 

 line, and buoyant organisms will ac- 

 cumulate at or near the convergence 

 line, producing streaks of floating ma. 

 terial (Fig. 4). 



"(3) Convection cells: Wind-driven 

 vertical convection cells may be estab- 

 lished which rotate alternately clock- 

 wise and counterclockwise with their 

 vertical axes perpendicular to the di- 

 rection of the prevailing wind. Floating 

 objects will accumulate in the region 

 between the descending connponents of 



"Thus there is no necessity to postu- 

 late obscure factors which would account 

 for a prodigious growth of dinoflagellates 

 to explain red water. It is necessary 

 only to have conditions favoring the 

 growth and dominance of a moderately 

 large population of a given species, 

 and the proper hydrographic and mete- 

 orological conditions to permit the ac- 

 cumulation of organisms at the surface 

 and to effect their further concentrations 

 in localized areas." [p. 409.] 



RYTHER, J. H., and R. R. L. GUILLARD. 



1962. Studies of nnarine planktonic diatoms. 

 II. Use of Cyclotella nana Hustedt for 

 assays of vitamin B12 in seawater. 

 Canad. J. Microbiol. 8(4): 437-445. 



SALSMAN, G. G., and W. H. TOLBERT. 



1963. Surface currents in the northeastern 

 Gulf of Mexico. Navy Mine Defense 

 Lab., Panama City, Fla., Rep. 209,43p. 



SATER, EDNA N. 



1954. Florida's red tide problem. Fish 

 Wildl. Serv., Fish. Leafl. 420, 11 p. 



This leaflet reviews generallythe red 

 tides from 1946-54 and research by 

 Federal, State, and private agencies. 



The theory is discounted that alleged 

 dumping of war munitions brought about 

 the kill of fish in 1946 and 1947. 



"Red tides occur on the west coast 

 of Florida only when certain peculiar 

 conditions prevail: after a period of 

 abnornnally heavy rainfall followed by a 

 shift from offshore to onshore winds. 

 These circumstances lead to the accu- 

 mulation of a mass of water of ab- 

 normally low salinity, which is kept 

 from dispersing seaward by the winds 

 blowing toward shore. In this water 

 mass, the organism G. brevis explodes 

 into what biologists call a bloom {an 

 extraordinary increase innumbers), and 

 becomes poisonous to fish life. As the 

 fish die, their decaying bodies release 

 nutrients which nourish the bloom and 

 intensify it. [p. 6.] 



"The theory is now held that the red- 

 tide organisms are able to multiply 



62 



