Bacterioplankton Community Shifts during a Spring Bloom of Aphanizomenon gracile and Sphaerospermopsis aphanizomenoides at a Temperate Shallow Lake

Climate change is enhancing the frequency of cyanobacterial blooms not only during summer but also in spring and autumn, leading to increased ecological impacts. The bacterioplankton community composition (BCC), particular, deeply affected by these blooms, although at same time BCC can play important roles blooms’ dynamics. However, more information still needed regarding species-specific blooms. goal this study was assess succession a hypereutrophic shallow lake (Vela Lake, Portugal) warm using metagenomic approach provide glimpse changes communities experience dominance Aphanizomenon-like bloom-forming species. shifts were studied 16S rRNA gene metabarcoding multivariate analyses. A total 875 operational taxonomic units (OTUs) retrieved from samples. In early spring, dominant taxa belonged Proteobacteria (mainly Alphaproteobacteria—Rickettsiales) Bacteroidetes (Saprospirales, Flavobacteriales Sphingobacteriales). end May, bloom co-dominated populations Aphanizomenon gracile, Sphaerospermopsis aphanizomenoides Synechococcus sp. developed persisted until spring. This led major shift favouring prevalence Alphaproteobacteria (Rickettsiales Rhizobiales, Caulobacteriales Rhodospirillales) followed These results contribute knowledge dynamics showing that strongly (directly or indirectly) Aphanizomenon-Sphaerospermopsis