Sensitive community responses of microbiota to copper in sediment toxicity test

Sediment contamination is widespread and can be toxic to aquatic ecosystems and impair human health. Despite their significant ecological function, meio- and microbiota in aquatic ecosystems have been poorly studied in conventional sediment ecotoxicity tests because of the difficulty in sample collecting and identification. In the present study, a novel DNA metabarcoding method was used to assess the effects of spiked copper (Cu) on benthic eukaryotic and prokaryotic communities in laboratory sediment toxicity tests with macroinvertebrates, the chironomid Chironomus tepperi and the amphipod Austrochiltonia subtenuis. In addition to the obvious toxic effects to experimental animals, microbiota (bacteria, protists, algae, and fungi) were significantly altered by spiked Cu in the sediments. The phylogenetic diversity of eukaryotic communities was decreased after spiked-Cu exposure. Even a low-spiked Cu treatment (125 mg/kg) altered structures of eukaryotic and prokaryotic communities in the amphipod experiment. The present study demonstrates that measuring microbiota communities will expand our understanding of the influences of contaminants on aquatic ecosystems. Particularly, the alterations of phylogenetic biodiversity of eukaryotic communities and the structure of sedimentary communities are sensitive indicators for sediment contamination, which can be incorporated in the monitoring and assessment of sediment quality.