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Scientific understanding of biotic effects on the water trophic level is lacking for urban lakes during algal bloom development stage. Based on the Illumina MiSeq sequencing, quantitative polymerase chain reaction (PCR), and multiple statistical analyses, we estimated distribution patterns and ecological roles of planktonic bacteria and eukaryotes in urban lakes during algal bloom development stage (i.e., April, May, and June). Cyanobacteria and Chlorophyta mainly dominated algal blooms. Bacteria exhibited significantly higher absolute abundance and community diversity than eukaryotes, whereas abundance and diversity of eukaryotic rather than bacterial community relate closely to the water trophic level. Multinutrient cycling (MNC) index was significantly correlated with eukaryotic diversity rather than bacterial diversity. Stronger species replacement, broader environmental breadth, and stronger phylogenetic signal were found for eukaryotic community than for bacterial community. In contrast, bacterial community displayed stronger community stability and environmental constraint than eukaryotic community. Stochastic and differentiating processes contributed more to community assemblies of bacteria and eukaryotes. Our results emphasized that a strong linkage between planktonic diversity and MNC ensured a close relationship between planktonic diversity and the water trophic level of urban lakes. Our findings could be useful to guide the formulation and implementation of environmental lake protection measures. [ABSTRACT FROM AUTHOR]

Deciphering ecosystem multifunctionality (EMF) driven by abiotic and biotic factors is crucial for evaluating soil nutrient cycling and retention. Yet, there is little information on whether microbial r/K‐selection can play the same role as community diversity to reflect EMF. Using Illumina MiSeq sequencing, phospholipid fatty acid (PLFA) technique, and multiple statistical analyses, we estimated linkages among salinity, soil EMF, community diversities, microbial r/K‐selection, and bacterial ecological assembly processes and phylogenetic signals in salinized agricultural soils (0.09–19.91 dS m−1). Salinity significantly negatively correlated with soil EMF, bacterial taxonomic and phylogenetic α‐diversities, and bacterial K‐selection represented by the Acidobacteria/Proteobacteria (Aci:Pro) ratio (0–0.50). There was a significantly positive correlation between bacterial K‐selection and soil EMF (Pearson's r = 0.545, p < 0.001). Deterministic processes (60.0–85.5%) dominated bacterial community assemblies along salinity gradients (i.e., 0–1, 1–2, 2–4, 4–8, 8–16, and >16 dS m−1), and salinity displayed a critical role in balancing stochastic and deterministic processes. To our knowledge, this study is the first to report elevated salinity decreased soil EMF and a bacterial shift from K‐ to r‐selection. Environmental constraint and phylogenetic conservatism showed strongly negative influences on bacterial K‐selection. These findings enrich the knowledge of bacterial diversity maintenance in salinized agricultural soils and reveal close linkage between bacterial K‐selection and soil EMF. Therefore, the bacterial K‐selection index of Aci:Pro could serve as a bioindicator for soil EMF. [ABSTRACT FROM AUTHOR]