The Population Dynamics of Freshwater Armored Dinoflagellates in a Small Lake in Mississippi

ABSTRACT

We investigated the temporal and spatial changes in population density of five dinoflagellates in Boondoggle Lake, a shallow, nutrient-poor lake in northern Mississippi. Dinoflagellate density and physicochemical conditions were assessed at three depths over a period of 16 months. We identified five Peridinium species (P. deflandrei, P. volzii, P. wisconsinense, P. limbatum and P. inconspicuum) and one Peridiniopsis species (P. polonicium). With the exception of P. inconspicuurn, none of these species has previously been reported in Mississippi. P. defandrei dominated the summer bloom (90% of the total dinoflagellate population) and reached a maximum population density of 2.75 X 10⁵ cells/L. P. wisconsinense and P. polonicium also had maximum densities in the summer. The increase of these species coincided with the onset of temperature and oxygen stratification, and their decrease coincided with lake mixing. P. volzii and P. limbatum reached maximum abundances in the spring and were less abundant than the summer species. Declines in these species were observed at the onset of stratification, with increases again after mixing.