[Precision of eDNA Metabarcoding Technology for Biodiversity Monitoring of Eukaryotic Phytoplankton in Lakes].

Environmental DNA (eDNA) metabarcoding provides a fast and efficient way to obtain biodiversity information that has been widely used in aquatic biodiversity monitoring and assessment. To facilitate the application of eDNA metabarcoding in China, the accuracy of metabarcoding data needs to be further assessed. Here, the eukaryotic phytoplankton in Dianchi Lake and the northern portion of Fuxian Lake were examined. The effect of sequencing depth on species diversity was also explored, and accuracy was evaluated by comparing the taxon overlap and coefficient of variation (CV) of the diversity index among biological replicates. The results showed that:① Sequencing depth significantly affected the taxon number and accuracy of alpha diversity determinations. The suggested sequencing depth for metabarcoding of eukaryotic phytoplankton in Dianchi Lake and Fuxian Lake is at least 30000. ② The OTU overlap was 45.97%±1.67% among three biological replicates, the genera overlap was 64.21%±3.25%, and the CV of alpha diversity was less than 10%. ③ Seventy-five and 90 genera of eukaryotic algae were identified in Dianchi Lake and Fuxian Lake, respectively, covering 62.5% and 71.05% of the morphologically detected species, respectively. ④ There was no significant variation in the diversity of eukaryotic algae with depth in Dianchi Lake, while diversity showed significant vertical patterns in Fuxian Lake. Overall, eukaryotic algal diversity was significantly lower in Dianchi Lake compared to Fuxian Lake, and diversity in the southern portion of Dianchi Lake was significantly higher than that in the central and northern portions (<0.05). Our study demonstrates the feasibility and accuracy of using eDNA-based techniques to monitor eukaryotic phytoplankton diversity, which supports the widespread application of eDNA metabarcoding in China.