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John J. Walsh and Karen A. Steidinger Department of MarineScience, University of South Florida, 140 Seventh Avenue South, St. Petersburg, FL 33701; and Florida Marine Research Institute, Florida Fish and Wildlife Conservation Commission, 100 Eighth Avenue S.E., St. Petersburg, FL 33701
Prediction of the consequences of harmful algal blooms for humans and other vertebrates is constrained by an inadequate understanding of the factors that promote their initiation. An analysis is made of ~3 decades of red tide strandings, associated fish kills, and concomitant dust loadings on the West Florida shelf. The larger summer blooms of a toxic dinoflagellate, Gymnodinium breve, appear to be regularly primed by an aeolian supply of nutrients. Wet deposition of Saharan mineral aerosols may alleviate iron limitation of diazotrophic cyanophytes, which in turn fuel the nitrogen economy of red tides in the eastern Gulf of Mexico. Vagaries of the wind-induced circulation and of selective grazing pressure on phytoplankton competitors within phosphorus-replete coastal waters then determine each year the residence times for exposure of G. breve- mediated neurotoxins to fish, manatees, and humans along the southeastern United States.
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