ABSTRACT Environmental DNA (eDNA) metabarcoding has emerged as a promising tool for monitoring fish diversity in a range of diverse aquatic realms. However, eDNA‐based monitoring of fish communities found in hydroelectric dam reservoirs has received relatively limited attention, especially in megadiverse regions such as the Neotropics. Herein, we evaluate eDNA metabarcoding as a biodiversity monitoring tool together with capture‐based fishing methods, in order to compare their efficacy and analyze their complementarity in the characterization of Neotropical fish communities. We obtained 147 water samples from three different sampling sites across the Irapé hydroelectric power plant reservoir (IRR) in Brazil across eight sampling events over 3 years (2019–2021). The 12S mitochondrial ribosomal RNA marker (~170 bp) was amplified and, using a curated reference library, the sequences were assigned to 115 Molecular Operational Taxonomic Units (MOTUs) corresponding to 30 taxa, 20 of which were identified to the species level. Gillnet sampling captured 484 individuals, representing 14 species, with Characiformes dominating the catches and the invasive Serrasalmus brandtii accounting for 68.8% of individuals. Environmental DNA consistently detected greater species richness across the sites and years, including 23 exclusive taxa not detected using gillnets. Beta diversity was high for both methods ( β > 0.93), driven mainly by species turnover. Nevertheless, redundancy analysis revealed distinct assemblage structures between methods, and no significant correlation was found between catch‐per‐unit‐effort and eDNA read abundance. These results underscore that when integrated with traditional methods, eDNA enhances biodiversity assessments and supports more comprehensive and cost‐effective monitoring programs in freshwater systems impacted by hydropower development.
Mendes et al. (Sun,) studied this question.