River benthic macroinvertebrates and environmental DNA metabarcoding: a scoping review of eDNA sampling, extraction, amplification and sequencing methods

Abstract

There is a growing body of literature on the use of molecular methods for the ecological assessment of rivers based on benthic macroinvertebrates. Previous research has established the benefits of the use of environmental DNA (eDNA) to assess benthic macroinvertebrate communities as being more efficient, less subjective, and non-invasive compared to traditional methods. The aim of this review is to synthesize the existing knowledge on eDNA sampling, extraction, amplification and sequencing methods regarding river benthic macroinvertebrate metabarcoding studies. Literature searches were performed using two online databases, and following a screening process, 46 papers published between 2012 and 2022 met the eligibility criteria to be included in the review. Since the use of river macrobial eDNA in ecology is a fast-evolving field, the results showed that the methodologies used vary considerably among studies. A variety of filters are used for capturing eDNA from water or preservative ethanol and different sources of eDNA (i.e., sediment, biofilm) are also explored. This review identified 12 different extraction methods and 15 different primer pairs that were used more than once in benthic macroinvertebrate eDNA metabarcoding studies. Therefore, there is a need for standardization of some key steps of the eDNA metabarcoding process to increase the comparability of the results and the robustness of the methods for further implementation into large-scale monitoring programs.