Environmental DNA of preservative ethanol performed better than water samples in detecting macroinvertebrate diversity using metabarcoding.

Aim: High‐throughput pipelines supported by eDNA metabarcoding have been applied in various freshwater ecosystems. Both eDNA in ethanol (EtOH) samples (ES‐eDNA) and in water samples (WS‐eDNA) can provide comprehensive classification lists with good taxonomic resolution and coverage for determining freshwater biodiversity and biomonitoring. But, the advantages of ES‐eDNA metabarcoding over WS‐eDNA metabarcoding remain unclear for routine assessments of diversity of benthic macroinvertebrates in streams. Location: Qiantang River Basin, China. Methods: Here, we compared ES‐eDNA and WS‐eDNA metabarcoding to evaluate the performance of two eDNA workflows in determining biodiversity and recovery of damaged macroinvertebrate communities. All eDNA samples from the environment and bulk specimen of macroinvertebrates were processed into available molecular operational taxonomic units (MOTUs) and identified to the level of genus. Results: WS‐eDNA detected more exact sequence variants (ESVs) (formerly referred to as operational taxonomic units; OTUs), than did ES‐eDNA (2,866 vs. 2,406), but fewer macroinvertebrate ESVs (381 vs. 481). Among sampling sites, the two eDNA workflows exhibited relatively large dissimilarity on inferred community composition (p <.001). Furthermore, ES‐eDNA metabarcoding exhibited more consistent with morphological identification approaches than did WS‐eDNA metabarcoding (24.24% vs. 17.63%, p =.002), especially for species identified by traditional morphology (morphotaxa). Main conclusions: Based on the attributes of ES‐eDNA and WS‐eDNA, it is suggested that ES‐eDNA metabarcoding performs better than does WS‐eDNA metabarcoding in detecting local biodiversity and was consistent with morphological results, while WS‐eDNA was more suitable for exploring biodiversity patterns on a broad scale, as it is the easiest and most convenient way to collect samples. Results of this study suggest ES‐eDNA metabarcoding could be an option in building molecular measurement biomonitoring programme based on EtOH sample used for preserving biological samples. [ABSTRACT FROM AUTHOR]