IMPLICATIONS OF PHYTOPLANKTON COMMUNITY COMPOSITION ON WEST
FLORIDA CONTINENTAL SHELF Karenia brevis BLOOMS. TIME SERIES TRANSECT
DATA AND CHEMOTAXONOMIC ANALYSES, 1999 THROUGH 2008.
Bradley A. Pederson1, Gary J. Kirkpatrick1, Anamari J. Boyes1 and Valeriy I. Palubok1
Mote Marine Laboratory, Sarasota, FL
Blooms of Karenia brevis are a common occurrence on the west Florida continental shelf and impact
ecology, human health and economics. A cross shelf monitoring transect has been maintained by Mote
Marine Laboratory offshore of Sarasota, FL since May 1998 with HPLC pigment analyses included since
July 1999. These data provide a long term view of phytoplankton community composition in relation to
bloom events of K. brevis. Phytoplankton chemotaxonomic classifications were determined using the
software package ChemTax® and community composition and environmental variables were incorporated
into multivariate analyses with the program Primer-E. Along the transect phytoplankton biomass (in
terms of total chlorophyll a) has shown a seasonal trend with pigment events typically occurring by
summer and lasting through the fall. During four of the nine years monitored those seasonal pigment
pulses appeared to have lead to, or coincided with, blooms of K. brevis. Multivariate analyses indicate
the trends in community composition were related to salinity and previous studies have shown a
correlation between K. brevis blooms and river flow. Bioassay studies conducted by Mote Marine
Laboratory however, demonstrate diatoms are first to respond to pulses of nutrients within the coastal
waters of Sarasota, FL so how then are K. brevis blooms linked to fresh water events? Time series data
imply cyanophyte events precede K. brevis blooms in west Florida coastal waters.