The temperature acclimatized swimming speed of selected marine dinoflagellates

Video measurements were used to monitor the temperature acclimatizedswimming speeds (24 hours exposure) of 11 species of marinedinoflagellates, some represented by different clones, on atemperature gradient plate. Although the inherent variabilityamong individuals within a population under the same treatmentwas high, each species or clone could be represented by a responsescatter plot that characterized its temperature-dependent swimmingability. A curve-fitting treatment of the data demonstratedthe similarity of the swimming speed versus temperature responsesfor repetitive trials on a single clone or for different clonesand the diversity of the swimming speed versus temperature responsesamong different species. Comparisons among populations includedviable temperature range, maximum swimming speed and responsecurve shape. All species swam over a broader temperature rangethan that over which growth was detected. Maximum swimming speedwithin the measured group occurred at a cell length of -35 µgThis possible optimum in cell size may result from the hydrodynamiccharacteristics of dinoflagellate swimming. Swimming speed variationamong dinoflagellate species can influence the competitive interactionswithin the group or with other kinds of phytoplankton and canaffect predator-prey interactions with herbivores.