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Bacteria-Phytoplankton
Interactions: The Influence of Marine Bacteria on Alexandrium spp. Blooms
in the Gulf of Maine
National Science Foundation
Blooms of the toxic dinoflagellate, Alexandrium fundyense, have
become a chronic problem affecting large areas of the Gulf of Maine on a
near-annual basis. Although hydrographic factors that influence A. fundyense
distributions are relatively well understood, factors that control the population
dynamics of A. fundyense within a given body of water are poorly defined.
Without a better understanding of these factors, it will not be possible
to develop effective simulation and predictive models of A. fundyense
toxicity needed by marine resource managers. While bacteria-A. fundyense
interactions have received little attention, our initial results indicate
that bacteria in the Gulf of Maine have the potential to dramatically stimulate
A. fundyense growth rates and yields. Bacterial stimulation of
A. fundyense varied seasonally, as did bacterial community composition.
We also have preliminary evidence of algicidal bacteria associated with
A. fundyense in a xenic culture. We are currently further characterizing
algicidal bacterial assemblages and working to isolate the causative organism(s).
Research goals: