Aquatic Sciences Meeting, Albuquerque 2001

CS15 Harmful Algal Blooms

Date: Tuesday, February 13, 2001, Time: 11:45:00 AM

Location: Cochiti/Taos

Penta, B, , University of South Florida, St. Petersburg, USA, penta@marine.usf.edu

Walsh, J, J, University of South Florida, St. Petersburg, USA, jwalsh@seas.marine.usf.edu

Tomas, C, R, University of North Carolina at Wilmington, Wilmington, USA, tomasc@uncwil.edu

Vargo, G, A, University of South Florida, St. Petersburg, USA, gvargo@seas.marine.usf.edu

COMPETITION AMONG MULTIPLE FUNCTIONAL-GROUPS OF PHYTOPLANKTON: A NUMERICAL RECIPE FOR HARMFUL ALGAL BLOOMS ON THE WEST FLORIDA SHELF

Spatially and temporally distinct phytoplankton blooms occur in West Florida shelf waters. Diatoms bloom in spring on the northern shelf, and blooms of Trichodesmium erythraeum and the harmful algal species Gymnodinium breve occur to the south in summer and autumn. Allocthonous sources of riverine, deep-sea, or atmospheric nutrients are needed to support such episodic pulses of phytoplankton biomass. Varying element ratios between the littoral and shelf-break supplies of nutrients, and differences in light utilization, uptake of inorganic and organic nutrients, settling losses, diel migratory behavior, and palatability to herbivores affect competition among eight functional groups of phytoplankton in a simulation model of the West Florida Shelf. Arrival of aeolian (iron containing) dust from the Sahara stimulates blooms of Trichodesmium in Peace River influenced waters. These blooms release dissolved organic nutrients into the water column which are utilized by two groups of dinoflagellates. The G. breve are better adapted for growth in strongly self-shaded patches and, more importantly, are avoided by most grazers due to their toxin production. Consequently, “red tides” of G. breve emerge on the West Florida shelf.

This Session Listing

Aquatic Sciences Meeting, Albuquerque 2001

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