title: High-frequency monitoring of the genetic diversity and the  potential toxicity of a Microcystis aeruginosa bloom in a French  shallow lake.
abstract: During cyanobacterial blooms, processes influencing the population dynamics of blooming species remain partially unexplained. To provide new information, we performed a high-frequency monitoring – every 2 days at six sampling points – of a Microcystis aeruginosa population blooming in a shallow lake. At each sampling date, there was no spatial heterogeneity in the ITS genotypic composition of the population and in the proportion of potentially microcystin- producing (mcyB+) cells, whereas high variations were recorded in cell abundances. In contrast, when looking at the temporal evolution of these parameters, the ITS genotypic composition of the population and in a lesser extent the percentage of mcyB+ cells displayed high variations during the growth phase of the bloom, but not during the plateau phase or the subsequent decline. This suggests that during the development of the bloom, there was no directional selection leading to the dominance of a restricted number of genotypes and that a balancing selection process permitted the maintenance of a high genetic diversity in the Microcystis population. Finally, no relationship was found between these variations occurring in the Microcystis population and those recorded for several environmental parameters, suggesting that many factors and processes interacting together might be involved in these variations.
authors: ISARA-Lyon, UMR 5023 LEHNA, Lyon, France.
authors: David
authors: D
authors: Pobel
authors: Jean-Jacques
authors: JJ
authors: Godon
authors: Jean-François
authors: JF
authors: Humbert
authors: Joël
authors: J
authors: Robin
mesh_terms: D004784:Environmental Monitoring / Q000379:methods; D005602:France; D005618:Fresh Water / Q000382:microbiology; D014644:Genetic Variation; D005838:Genotype; D057097:Harmful Algal Bloom; D060106:Lakes / Q000382:microbiology*; D052998:Microcystins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D046931:Microcystis / Q000145:classification / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity
chemical_list: D052998:Microcystins; C078588:microcystin