Diversity patterns and spatiotemporal dynamics of phytoplankton and zooplankton in Lake Taihu with blooms

As typical large shallow lake, the Lake Taihu bloom in China has caused serious environmental and social problems. Here we employed 9 gene markers (three regions of 18S, one region of 28S, one region of 23S, two regions of 16S and two regions of rbcL) with cost-effective multiplex PCR to reveal the diversity patterns and spaiotemporal dynamics of Cyanobacteria, eukaryotic phytoplankton and zooplankton among the whole lake from April to Summer by NGS. 5 gene markers were new designed in this study (18S-v4-5, 28S, 16S-new, rbcL-Chlo and rbcL-Cry). The diversity analysis for each of phytoplankton phyla and zooplankton was performed in species, genus, family, and pylum level respectively, which indicated that the taxonomic assignments of each gene marker were different from other markers. The new designed markers were effective for broad or specific taxonomic-range identification. The proportion of phytoplankton phyla and zooplankton was generally consistent between Spring and Summer, but the top taxa in species, genus and family level were different between the two seasons. The reads abundance in Summer is much higher than that in Spring. The NMDS analysis showed that the diversity of phytoplankton and zooplankton in Spring were greatly different from that in Summer, but there was no much difference for the diversity among the different regions of the lake. The CCA analysis indicated that the temperature was the remarkable environmental factor that affected the diversity of phytoplankton and zooplankton from Spring to Summer. The molecular network analysis told that most correlations among taxa of phytoplankton, zooplankton and fungi was positive. All the results suggest that the temperature possibly plays key role in diversity dynamics of Cyanobacteria, eukaryotic phytoplankton and zooplankton in Lake Taihu. The multiplex PCR strategy with multiple gene markers in this study will contribute to reveal diversity of cyanobacteria and eukaryotic phytoplankton and zooplankton in aquatic environments for bloom control. In the future study, we will design more different length of gene fragments for compatible with different NGS sequence platform, and associate the bacteria to the diversity patterns.