CS16 Harmful Algal Blooms
Date: Wednesday, June 12, 2002
Time: 4:00:00 PM
Location: Sidney
BarnettAB, Center for Environmental Observation Technology and Research (CEOTR), Dalhousie University, Halifax, Canada, abbarnet@is2.dal.ca
Normandeau, C, , CEOTR, Dalhousie University, Halifax, Canada, c.normandeau@dal.ca
Ryan, C, , CEOTR, Dalhousie University, Halifax, Canada, Cathy.Ryan@dal.ca
Cullen, J, J, CEOTR, Dalhousie University, Halifax, Canada, John.Cullen@dal.ca
Behavioral and physiological variability among strains of the toxic dinoflagellate, Alexandrium fundyense, from the Gulf of Maine region.
Some dinoflagellate species migrate vertically, potentially increasing nutrient availability and/or avoiding damaging irradiance. It has been shown that a strain of Alexandrium tamarense from the Gulf of St. Lawrence migrates when N is depleted in the surface layer, whereas a strain of A. fundyense from Casco Bay, Maine, does not. This difference in behavior has strong implications for understanding and modeling the population dynamics of Alexandrium in nature. Can it be assumed that A. fundyense does not migrate? We assess the influence of nutrient availability on vertical migration and photosynthetic responses of six strains of A. fundyense from the Bay of Fundy and Casco Bay. Each strain was placed in a thermally stratified 2m tall tank and sampled from nutrient replete through N-deplete conditions. Although the strains differed little in simple physiological measures (e.g., maximum growth rate at 15 deg C), fundamental differences in behavior were observed: some strains migrated, some did not. A comparison of photosynthesis-irradiance parameters, protective pigment concentrations, and fluorescence parameters between migrating and non-migrating strains reveals physiological correlates of differences in behavior. Results of this study have direct implications for modeling the population dynamics of Alexandrium in the Gulf of Maine.