Environmental DNA Metabarcoding Detects Predators at Higher Rates Than Electrofishing

Abstract

There are numerous downsides and risks associated with electrofishing; hence, environmental DNA (eDNA) metabarcoding is becoming increasingly common in aquatic ecological studies. Generally, researchers agree that eDNA metabarcoding is more sensitive than electrofishing, and that eDNA metabarcoding is better at detecting rare species. As predatory species tend to be rarer than prey species, eDNA metabarcoding should hypothetically detect more predator species than electrofishing. Instead of supporting the notion that eDNA must replace electrofishing, or that eDNA and electrofishing must display the same results, the current study aims to establish the strengths and weaknesses of eDNA metabarcoding when compared to electrofishing. eDNA metabarcoding and electrofishing data were collected on three sampling dates at four experimental sites. A RV coefficient analysis confirmed that the eDNA metabarcoding data (RV = 0.395, p = 0.057) are statistically different from the electrofishing data. A paired Wilcoxon signed rank test revealed that eDNA data collection techniques detect more predatory species than electrofishing (p = 0.041). When the analysis was conducted for prey species a statistically significant difference did not occur (p = 0.661). Overall, the results of the study suggest that eDNA metabarcoding does not display the same results as electrofishing due to eDNA metabarcoding detecting predatory species at higher rates. The combined use of eDNA alongside electrofishing can help mitigate electrofishing's bias against predatory species, while electrofishing can address reliability concerns associated with eDNA. This collaborative approach ultimately enhances the accuracy of fish community assessments.