Transcriptional effects of metal-rich acid drainage water from the abandoned Løkken Mine on Atlantic salmon (Salmo salar) smolt.

Runoff of metals represents one of the major environmental challenges related to historic and ongoing mining activity. In this study, transcriptomics (direct RNA sequencing [RNA-seq] and reverse-transcription quantitative polymerase chain reaction [RT-qPCR]) was used to predict toxicity of metal-rich acid mine drainage (AMD) water collected in the abandoned copper (Cu) mine called Løkken Mine on Atlantic salmon liver and kidney, the main target organs of Cu-induced toxicity in fish. Smolts were exposed to control and diluted AMD water, which contains a mixture of metals but is especially enriched with Cu, at 4 concentrations in freshwater (FW) for 96 h, and then were transferred to and kept in seawater (SW) for another 24 h.