Summary 



One hundred and twenty-three phytoplankton samples from the primary study area 

 were examined for the presence of the toxic dinoflagellate Gymnodinium breve. Eighty 

 percent of these samples contained G. breve cells. Seventy samples from the upper half of 

 the water column were examined in detail, and quantitative counts confirmed that 94% 

 contained some G. breve cells while 65% contained >50 cells r\ These concentrations are 

 far below those considered a 'TDloom" (>5 x 10^ cells 1'^). Comparative samples from other 

 areas in the Gulf suggest that G. breve concentrations in the primary study during the March 

 1990 sampling period were within "normal backgroimd levels" but consistently higher than 

 quantitative counts of samples from similar areas or from the primary study area later in the 

 sunamer. 



The discolored water patches noted during aerial observations of the primary study 

 area were blooms (approx. 1 x 10^ cells 1"^) of the dinoflagellate NoctUuca spp. This genera 

 is not normally known to be toxic. However, it should be noted that a toxic dinoflagellate 

 species, Gonyaulax monalata, was found in elevated concentrations near the Mississippi delta 

 in late summer 1990. 



Literature Cited 



Baden, D.G., T.J. Mende, M.A. Poli and R.E. Block. 1984. Toxins from Florida's red tide 

 dinoflagellate Ptychodiscus brevis. Pages 359-367 in E.P. Ragelis (ed.), Seafood toxins. 

 American Chemical Society, Washington, D.C. 



Connell, C.H. and J.B. Cross. 1950. Mass mortality of fish associated with the protozoan 

 Gonyaulax in the Gulf of Mexico. Science 112:359. 



Geraci, J.R. 1989. Qinical investigations of the 1987-1988 mass mortality of bottlenose 

 dolphins along the U.S. central and south Atlantic coast. Final report to National 

 Marine Fisheries Service and U.S. Navy, Office of Naval Research and Marine 

 Mammal Commission, April 1989. 63 pp. 



Gunter, G., G.F. Walton Smith, and R.H. Williams. 1947. Mass mortality of marine animals 

 on the lower west coast of Florida, November 1946-January 1947. Science 105:256-257. 



Gunter, G., R.H. Williams, C.C. Davis and F.G. Smith. 1948. Catastrophic mass mortalities 

 of marine animals and coincidental phytoplankton bloom on the west coast of 

 Florida, November 1946 - August 1947. Ecological Monographs 18:309-324. 



Pierce, R.H. 1986. Red tide {Ptychodiscus brevis) toxin aerosols: a review. Toxicon 24:955- 

 965. 



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