Blooms of the toxic dinoflagellate <em>Karenia brevis</em> have devastating human, environmental and economic impacts in the Gulf of Mexico.  We examined the efficacy of 15 potential mitigation compounds identified from the literature to simultaneously mitigate both cells and dissolved brevetoxins of <em>K. brevis</em> in laboratory experiments. While the majority of compounds had a negative effect upon cell concentrations, most reductions in cell abundance after 24 or 48 hours resulted in either no change in dissolved brevetoxin concentration (e.g. barley straw extract, linoleic acid), an increase in total dissolved brevetoxins (e.g. <em>Gracilaria curtissae</em>), or a conversion between brevetoxin forms, specifically from PbTx-2 to PbTx-3 (e.g. chitosan).  Of the compounds tested, the high dose of the macroalgal species <em>Gracilaria lemaneiformis</em> was the most effective in mitigating both cells and brevetoxins, eliminating 100% of cells and 61 % of total brevetoxins after 48 hours.  Effective mitigation of <em>Karenia brevis</em> blooms requires elimination of both cells and dissolved brevetoxins and concurrent monitoring of mitigation efforts. 

Primary Presenter: Cynthia Heil, Mote Marine Laboratory (cheil@mote.org)

Authors:

Amanda Muni-Morgan, University of Florida  (a.munimorgan@ufl.edu)

Richard Pierce, Mote Marine Laboratory  (rich@mote.org)

Sarah Klass, Mote Marine Laboratory  (sklass@mote.org)

Patti Holland, Mote Marine Laboratory  (pholland@mote.org)