CS16 Harmful Algal Blooms
Date: Wednesday, June 12, 2002
Location: Poster Session - VCC
VargoGA, University of South Florida, St. Petersburg, USA, vargo@seas.marine.usf.edu
Heil, C, A, USF, St. Petersburg, USA, cheil@seas.marine.usf.edu
Ault, D, N, USF, St. Petersburg, USA, dspence@seas.marine.usf.edu
Neely, M, B, USF, St. Petersburg, USA, mneely@seas.marine.usf.edu
Murasko, S, , USF, St. Petersburg, USA, smurasko@seas.marine.usf.edu
Havens, J, , USF, St. Petersburg, USA, jhavens@seas.marine.usf.edu
Lester, K, M, USF, St. Petersburg, USA, klester@seas.marine.usf.edu
Walsh, J, J, USF, St. Petersburg, USA, jwalsh@seas.marine.usf.edu
Weisberg, R, , USF, St. Petersburg, USA, rweisberg@seas.marine.usf.edu
Steidinger, K, A, FMRI, St. Petersburg, USA, Karen.Steidinger@fwc.state.fl.us
Four major toxic Karenia brevis (= Gymnodinium breve) blooms occurred on the West Florida Shelf between October, 1998 and January, 2002. Each bloom was characterized by different population abundances (one thousand to 5.4 million cells per liter ) and spatial extent (hundreds to thousands of square kilometers). Commonalities in the hydrographic and nutrient regime, and indicators of nutrient status are being examined to assess initiation and maintenance mechanisms. All blooms appeared after breakdown of vertical stratification, with three of the blooms associated with nearshore thermal or salinity fronts after onshore transport. No one hydrographic feature characterized the early stages of each bloom. Water column DIN:DIP molar ratios were generally less than 1.0 suggesting N-limitation paralleling P-enrichment from nearby phosphatic deposits. Particulate C:N molar ratios for two of the blooms ranged from near Redfield , 5 to 7, to values less than 1.0 for populations greater than 5 million cells per liter during the 1999-2000 bloom, with a range of 14 to 35 for populations just prior to bloom termination. Overall, the blooms cannot be characterized by a single physiological indicator.