is lowered at 2° per hour, they be- 

 come immobile and cytolize between 

 12° and 14° C, but when lowered at 

 1° per hour they are active until they 

 reach 8° to 10° C. 



G. breve survive salinities from 24to 

 40 p.p.t., but become inactive at 20 

 p.p.t. or 42 p.p.t. (90 to 100 percent 

 of culture). Also see Aldrich and Wilson 

 (1960), 



G. breve survived pH from 7.0 to 8.6; 

 growth was best from 7.3 to 8.1. A 

 mature culture declining from its peak 

 growth frequently reverts to the growth 

 phase if one of several nutrients is 

 added, namely: B 12. thiamine, biotin, 

 phosphate, ammonia, a group of trace 

 metals, or soil extract. 



If fish autolysate is added to the 

 original culture medium, it frequently 

 stinnulates excessive bacterial growth 

 and the culture dies. In mass cultures 

 which are cropped and new media added 

 the highest concentration of G. breve is 

 normally 4 million per liter, and never 

 as high as 5 million. Fish autolysate 

 added to a 3.5-million culture raised 

 it to 9 1/2 million in 4 days but it fell 

 to zero in 1 week. 



The author believed there is a mu- 

 tually beneficial relationship between 

 G. breve cind "the dominant bacteriad 

 contaminamt of mass cultures." He says 

 G. breve produce carbohydrates which 

 could account for the increased bac- 

 terial growth, while bacteria produce 

 vitamnin Bj2 needed by G. breve . 



In confirmation of this mutuality of 

 interests the author had sealed cultures 

 of G. breve cind G. splendens that were 

 maintaining themselves after 2 amd 2 1/2 

 years, respectively. 



The author could not subculture 

 G. breve without adding soil extract 

 to the medium. Ashed soil extract 

 would not substitute, amd neither would 

 known chemicals. Soil extract dialyzate 

 is not beneficial but the dialyzed por- 

 tion remaining is beneficial, indicating 

 orgauiic compovmds of high molecular 

 weight. 



Of several metals tested, copper was 

 most toxic. 



WILSON, WILLIAM B. 



1958. Compounds toxic to red tide orga- 

 nisms. In Annual report of the Gulf 

 Fishery Investigations for the year 

 ending June 30, 1958. U.S. Fish Wildl, 

 Serv., p. 66-67. 



Discusses progress on factors af- 

 fecting the toxicity of copper to G. breve . 



"Tests on the toxicity of fluorescine 

 dye to G. breve indicated that it is not 



toxic in concentrations of 100 parts per 

 million. These results indicate that 

 fluorescine dye can be used as a marker 

 in field experiments without altering 

 the results." [p. 67.] 



WILSON, WILLIAM B. 



195 9a. Evaluating toxicity of dissolved sub- 

 stainces to microorganisms using di- 

 alysis membrames. In Galveston Bio- 

 logical Laboratory fishery research for 

 the year ending June 30, 1959, p. 100- 

 102. U.S. Fish Wildl. Serv., Circ. 62. 



To test the effects of copper in the 

 field, known concentrations of Proro- 

 centrum sp. were placed in bags made 

 of dialysis membrane. The bags were 

 suspended inside perforated polyethyl- 

 ene bottles for protection from macro- 

 organisms. 



"... Between two aind five hours 

 were required for the inside concentra- 

 tion to approach 0.8 (i. g. at. Cu/l with an 

 outside concentration of 1.6 jj,g.at. Cu/l. 

 An outside concentration of 0.8 |i g.at. 

 Cfi/l did not raise the inside concentra- 

 tion to a comparable amount within 24 

 hours." [p. 101-102.] 



WILSON, WILLIAM B. 



1959b. Nutritional studies on red tide. In 

 Galveston Biological Laboratory fishery 

 research for the year ending June 30, 

 1959, p. 72-74, U.S. Fish Wildl, Serv., 

 Circ. 62. 



"The minimum calcium content of 

 media in which G. breve grew was ap- 

 proximately one -sixth the amount of 

 standard sea water (salinity - 35. 5%o), 

 or approximately 70 mg/l(l,7 mgat/1). 

 An increase in calcium to twice the 

 amount of open oceain water was not 

 detrimental as long as the phosphorus 

 content was less than 5 |j,g,at/l. If the 

 calcium content is between 140 and 

 400 mg/1, cultures have grown very 

 well in most concentrations of phos- 

 phorus. There was some linnitation of 

 growth if the phosphorus was less tham 

 0.04 p,g.at/l or more thain 100|j.g.at/l. 

 In the latter case, the high phosphorus 

 content caused precipitation, as did 

 excessive calcium. When precipitation 

 occurred, G. breve did not grow. 



"The results of the calcium -phos- 

 phorus experiments indicate that if the 

 calcium concentration was the same as 

 that of normal open ocean water (ap- 

 proximately 400 mg/1), inorgamic phos- 

 phorus content should be 0.4(i,g.at. per 

 liter or greater for the medixun to 

 support good growth of G. breve . Opti- 

 mum growth occurred within a rainge of 



73 



