DNA Metabarcoding Meets Experimental Ecotoxicology: advancing Knowledge on the Ecological Effects of Copper in Freshwater Ecosystems

DNA (DNA) metabarcoding is a molecular tool that may revolutionise the way in which biological communities are assessed. The tool has the potential to allow a much larger proportion of the biological community to be identified more reliably and rapidly than by current methods of analysis, including meio- and microbiota that would otherwise be missed. Here, DNA metabarcoding was performed to assess the effects of copper on the establishment of a benthic eukaryote community within a series of environmentally relevant copper-contaminated, freshwater mesocosms. The organisms present from the micro- to macroscale were characterised using this method. While taxonomic richness of the eukaryote community increased in control and low copper treatments (<. 200. mg/kg dry wt particulate copper; <. 5. μg/L pore water copper), it remained constant or declined over time in higher copper treatments (>. 400. mg/kg dry wt; >. 18. μg/L). The response observed in the composition of the benthic eukaryote community was more subtle, with significant differences apparent between all treatments during the initial establishment of the community, even the control (4.6. mg/kg dry wt; 1.5. μg/L) and very low (71. mg/kg dry wt; 2.8. μg/L) copper-contaminated treatments. This response was much more sensitive than that observed by a traditional analysis of the macroinvertebrate community over the same time period. All the taxa identified to be sensitive to copper were meio- and microbiota including Chlorophyta, Nematoda, Bacillariophyta and Fungi. This study demonstrates the potential power of DNA metabarcoding for ecotoxicological studies and emphasises the need to incorporate and meio- and microbiota into bioassessment processes.