Can different molecular identification approaches to aquatic insects effectively supplement morphology-based biomonitoring in a multi-gradient river system in Japan?

Aquatic ecosystems are under immense pressure brought by anthropogenic stressors. In Japan’s Fujikawa River Basin, significant land use change such as flood-mitigating structures and river dredging in the past decade are present. This in turn affects the riverine biological and nutrient continuity. Aquatic insects are widely used as biological indicators because they inhabit diverse ecological niches. However, complexity arising from morphology-based monitoring limits ecological implications due to coarse taxonomic identification. Here, the study applied DNA metabarcoding (DM) and species delimitation (SD) with the aim to supplement morpho-based biomonitoring in 25 stream sites across the river basin. DNA for each morpho-taxa was extracted, with 16s rRNA and Cytochrome Oxidase I (COI) region amplified and sequenced using NGS. Then, sequence data were filtered, clustered into Amplicon Sequence Variants (ASVs), and matched to species by BLAST (≥ 97% identity). For SD, a combination of phylogenetic analyses and ABGD species delimitation were performed and assigned in Molecular Operational Taxonomic Units (MOTUs). Based on the Chironomid data, DM findings has 25 taxa while SD-based data has 52 MOTUs. Forward selection CCA revealed that DM-based model has sensitivity with pH and Cl- while for SD-based result, it was pH, Cl-, and water velocity. Negative binomial GLM showed that most biodiversity indices based from molecular identification had contrasting response with Cl- and pH. These findings highlight the sensitivity of molecular approaches in supplementing morphology-based biomonitoring.

Presentation Preference: Standard Oral (12 Minutes)

Primary Presenter: John Claude Renan Salluta, University of Yamanashi (g23dtka4@yamanashi.ac.jp)

Authors:

Kazuaki Ohtsuki, University of Yamanashi  (kotsuki@yamanashi.ac.jp)

Tamato Shimizu, University of Yamanashi  (t22ce023@yamanashi.ac.jp)

Takashi Nakamura, University of Yamanashi  (tnakamura@yamanashi.ac.jp)

Sakiko Yaegashi, University of Yamanashi  (sakikoy@yamanashi.ac.jp)