Characterization of phytoplankton seed banks in the sediments of a drinking water reservoir

AbstractThe presence, abundance, and composition of algal and cyanobacterial populations in lake sediments were evaluated in Lake St. Charles (Quebec City, Canada), an urban drinking water reservoir. This water body has recently experienced cyanobacterial blooms, and we tested the hypothesis that a seed population of noxious taxa that could potentially re-inoculate the water column was present in the lake sediments. Cores were obtained from 8 sites spanning a range of depth and sediment conditions in both basins of the lake; sampling was from May to October over 2 years. Three techniques were applied: observation of the surficial sediments by epifluorescence microscopy; pigment analysis by high-performance liquid chromatography (HPLC); and laboratory enrichment culture of sediment samples under different light, temperature, and nutrient conditions. These analyses revealed the presence of diverse phytoplankton pigments and fluorescent cells in the sediments, with a predominance of diatoms along with dinofl...