Spatial and temporal distribution patterns and driving mechanisms of ciliate communities in the midstream and downstream reaches of the Lhasa River

Abstract

Aims: As a high-altitude water area, the Lhasa River's aquatic ecosystem has a high research value due to its special environmental conditions. In recent years, studies on the high-altitude water area have gradually increased, but there are few studies on the community structure of ciliates in the Lhasa River. We conducted this study to explore the composition pattern, spatial and temporal diversity pattern, and maintenance mechanism of ciliate communities in the midstream and downstream reaches of the Lhasa River. Methods: Seventeen samples were collected from the middle and lower reaches of the Lhasa River in May 2015 and August 2015, and October 2016. In-vivo observation, Rugo's iodine solution fixation staining, and Wilbert's protein silver method were utilized for species identification. The spatial and temporal differences of community structure were analyzed by the Shannon diversity index, Margalef index, and richness. The interactions between ciliate groups were analyzed through co-occurrence network. The effects of physical and chemical factors on ciliate community structures were investigated using redundancy analysis (RDA).

Distribution Patterns and Driving Factors of the Phytoplankton Community in the Middle Reaches of the Yarlung Zangbo River

“…In the co-occurrence network, the positive and negative correlations of edges between two nodes represent the reciprocal and competitive relationship between connected species, respectively. The positive correlations between network nodes (Figure 6) suggest a synergistic relationship between species, and organisms from the same group often have antagonistic effects due to the competition for resources [50,51]. The positive correlation ratio of tributaries was higher than that in the main stream, suggesting a higher synergistic effect of the phytoplankton community in the tributaries, which dominated the phytoplankton community.…”