Diversity and Their Response to Environmental Factors of Prokaryotic Ultraplankton in Spring and Summer of Cihu Lake and Xiandao Lake in China

Ultraplankton plays an important role in the biogeochemical cycles of aquatic ecosystems. Based on 16S rRNA gene sequencing technology, the community structure composition of prokaryotic ultraplankton and its relationship with environmental factors were analyzed. The results showed that Cihu Lake was experiencing eutrophication and that Xiandao Lake was in the process of changing from mesotrophic to oligotrophic conditions. Cihu Lake and Xiandao Lake were regulated primarily by nitrogen nutrients. Proteobacteria, Bacteroidota, Cyanobacteria, and Actinobacteriota were the major phyla of prokaryotic ultraplankton in both lakes. Among them, Cyanobacteria dominate in the summer in Cihu Lake, which can have seasonal cyanobacterial blooms. Seasonal variation significantly affects the diversity and community structure of prokaryotic ultraplankton in the lakes, with temperature and dissolved oxygen being the key environmental factors determining plankton community composition. The PICRUSt functional prediction analysis indicated a higher water purification and exogenous pollution remediation capacity of the microbial communities of Xiandao Lake, as well as in the spring samples of Cihu Lake. In this study, the diversity and spatial-temporal succession patterns of prokaryotic ultraplankton in Cihu Lake and Xiandao Lake were elucidated, providing a useful reference for the lake environmental protection and water eutrophication management in Cihu Lake and Xiandao Lake.