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THE RED-TIDE DINOFLAGELLATE, ALEXANDRIUM MONILATUM, SUPPRESSES GROWTH OF MIXED NATURAL PHYTOPLANKTON
Citation:
Juhl, A R. THE RED-TIDE DINOFLAGELLATE, ALEXANDRIUM MONILATUM, SUPPRESSES GROWTH OF MIXED NATURAL PHYTOPLANKTON. Presented at AWRA Spring Speciality Conference: Agricultural Hydrology and Water Quality, Salt Lake City, UT, Feb. 8-14, 2003.
Description:
Alexandrium monilatum is a large, chain-forming, autotrophic dinoflagellate associated with red-tides and fish kills along the US Gulf of Mexico coast. When cultured inocula of A. monilatum were added to nutrient-amended seawater samples, growth rates and biomass yields of the natural phytoplankton community were depressed. Growth suppression was a function of A. monilatum cell concentration. A. monilatum addition depressed total phytoplankton yield by as much as a factor of 10 relative to controls without added A. monilatum. Growth suppression also occurred in response to addition of A. monilatum culture filtrates and cell lystates. Conceptually, suppressing growth of competing phytoplankton may enhance nutrient availability for A. monilatum. However, growth suppression of natural phytoplankton only occurred with high A. monilatum cell concentrations, implying that this behavior could support bloom persistence, but is unlikely to be important in early bloom formation. Whereas previous studies of dinoflagellate allelopathy tended to focus on interactions between individual cultured species, these results describe a general allelopathic effect of a red-tide dinoflagellate on mixed, natural phytoplankton.