Diversity and Activity of Bacterioplankton in Shallow Lakes During Cyanobacterial Blooms

One of the global issues concerning aquatic environments is the increasing frequency of cyanobacterial blooms. These blooms can lead to oxygen depletion and the release of potent toxins, potentially disrupting the bacterial communities responsible for organic matter transformation and mineralization. This study aimed to examine the structural and functional diversity of bacterioplankton in three eutrophic lakes during periods of cyanobacterial bloom. The microbial communities were analyzed using high-throughput sequencing of the 16S rRNA gene, and the abundance and activity of bacterioplankton were assessed with fluorescent markers. The findings revealed that dead bacterial cells predominated in the water samples (61.16%). Taxonomic profiling identified Cyanobacteria (45.38%), Proteobacteria (20.99%), Bacteroidetes (11.37%), Actinobacteria (8.08%), and Verrucomicrobia (4.04%) as the dominant phyla. Additionally, the structure of the bacterial communities (β-diversity) showed significant variation across the lakes, but this variation did not correlate with seasonal changes. No marked effect of abiotic factors on the structural or functional diversity of the bacterioplankton was observed. These results suggest that, despite the presence of cyanobacterial dominance, microbial community structure is more closely tied to the type of lake rather than seasonal or abiotic factors. Further studies are needed to better understand the factors driving these community patterns.