Presenter: Blake A. Schaeffer
Advisor(s): Daniel Kamykowski
Author(s): Blake A. Schaeffer, Daniel Kamykowski, Geoff Sinclair and Anita McCulloch
Graduate Program: Marine, Earth, and Atmospheric Sciences

Title: Implications for how Karenia brevis becomes a harmful algal bloom

Abstract: Karenia brevis is a harmful algal bloom dinoflagellate typically located in the Gulf of Mexico and along the east coast of Florida.  Blooms that begin offshore eventually move shoreward causing fish kills and respiratory problems in humans.  This project showed how K. brevis responded to high-light conditions both in the laboratory and in the field.  High light caused increased toxin concentrations and decreased lipid concentrations, specifically the sterol class.  One suggested function for sterols was protection against the membrane disrupting effects of brevetoxins.  K. brevis may take advantage of its toxicity, as a unique survival strategy, by reducing sterol concentrations and releasing toxins into the surrounding environment.  Trends reported here indicated that K. brevis was relatively benign from sunrise to mid-morning.  From mid-morning until mid-afternoon K. brevis had the potential to be highly toxic.  Some of the potency may be lost as sterol concentrations recovered late in the evening.  The physiological response of K. brevis to changing light in the field could have dramatic consequences for people at the beach.  For example, peak time for beach attendance occurred between 1100 and 1500 at Sarasota beaches.  Experimental persons involved in brevetoxin aerosolized studies suggested their greatest symptoms occurred between 0900 and 1500.  These times coincide with the estimated time K. brevis would be highly toxic by producing the highest toxin concentrations and reducing sterol concentration. Increased toxin concentrations with the enhanced transport through lower sterol concentrations, combined with breaking waves, onshore winds and peak beach attendance set the stage for human respiratory problems.