Structure and Composition of Sediment-Associated Bacterial and Eukaryotic Communities in the River–Lake System of Poyang Lake, China

Microorganisms play key ecological roles in aquatic and terrestrial environments. However, little is known of the differences in physicochemical and geographical factors influencing the bacterial and eukaryotic communities and of the relative contribution of these two types of predictors in such systems. Here, we investigated the structure and influential factors on bacterial and eukaryotic communities within the river-lake ecosystem sediments using high-throughput DNA sequencing. Numerous physicochemical parameters and geographical locations were measured among 15 sampling sites in the river-lake system of Poyang Lake. Bacterial communities were dominated by Proteobacteria (32.08%), Acidobacteria (16.58%), and Chloroflexi (14.39%), while eukaryotic communities were dominated by Fungi (63.32%) and Alveolata (10.2%). Both bacterial and eukaryotic community structures statistically correlated with C, N, and Fe, but only bacterial community structure significantly correlated with pH, ON, and Fe. Variation partitioning analysis revealed that physicochemical parameters controlled strongly both bacterial and eukaryotic communities, whereas the direct influence of geographical coordinates and a combination of physicochemical parameters and geographical coordinates controlled relatively small. Bacterial community (31.64%) exhibited a stronger influence by physicochemical parameters than the eukaryotic community (17%).