Seasonal variation significantly affected bacterioplankton and eukaryoplankton community composition in Xijiang River, China

Both bacterioplankton and eukaryoplankton communities play important roles in the geochemical cycles and energy flows of river ecosystems. However, whether a seasonal change in bacterioplankton and eukaryoplankton communities is synchronous remains unclear. To test the synchronicity and analyze how physical and chemical environmental factors affect these communities, we compared bacterioplankton and eukaryoplankton communities in surface water samples between March (dry season) and June (rainfall season) considering water environmental factors. Our results showed that there was no significant difference in operational taxonomic unit number, Shannon index, and Chao1 index in bacterioplankton and eukaryoplankton communities between March and June. However, principal component analysis showed that the communities were significantly different between the sampling times and sampling sites. Water temperature (WT), oxidation–reduction potential (ORP), water transparency (SD), NO3-N, and NH3 significantly influenced bacterioplankton communities, and WT, SD, ORP, and NH4-N significantly influenced eukaryoplankton communities in the river. These results implied that compared with the sampling sites, sampling times more significantly affected the bacterioplankton and eukaryoplankton river communities by influencing WT, ORP, SD, and nitrogen forms.