| Picocyanobacteria (PC) are microscopic blue green algae responsible for a tenth of the total primary production of marine and freshwater systems. In this research, the ecology of temperate lake PC populations and their flow cytometry signatures were studied.; In the first chapter, I examined the relative importance of growth versus losses of picocyanobacteria (PC) and the influence of physical and chemical variables on their in situ abundance in 48 temperate freshwater lakes. Growth and loss rates of PC were estimated from in situ incubations using a selective metabolic inhibitor technique and abundance of PC was determined by epifluorescence microscopy.; In the second chapter, I examined the use of flow cytometry to identify PC and determine their abundance in lake water samples.; The background noise appears higher in lake samples than marine ones. The source of this noise needs to be identified and corrected in future studies. However, flow cytometry is a promising tool for examining pigment distributions and for rapid assessments of the phytoplanktonic community. Epifluorescence remains the most reliable technique to determine PC abundance and pigment composition in freshwater lakes. (Abstract shortened by UMI.)... |
