| dc.description.abstract | Anthropogenic activities are putting marine and freshwater ecosystems under increasing pressure and global climate change is causing transformations in ecosystems and food chains worldwide. Invasive species pose one of the greatest threats to natural diversity and the endemic species essential for ecosystem balance. In November 2021, Gillsvann in Kristiansand, Norway, was treated with rotenone with the aim of eradicating the invasive species Northern pike (Esox lucius) from the lake. The effectiveness of the treatment was monitored using environmental DNA (eDNA) analysis. The primary objective was to investigate the presence of Northern pike eDNA in the lake from November 2021 (after the treatment) to November 2022. Monthly water samples were collected from 14 different locations in Gillsvann and analyzed using real-time PCR with species-specific eDNA. The findings of the study revealed that the presence of Northern pike eDNA was observed consistently each month up until the month of April in the year 2022. However, from the month of May until November in the same year, there was no detection of Northern pike eDNA, suggesting that the species may have been successfully eliminated from the lake. The second objective was to analyze eDNA of three-spined stickleback (Gasterosteus aculeatus) to assess the re-establishment of endemic species. The results suggest that three-spined stickleback likely re-invaded the lake following the rotenone treatment, with eDNA levels returning to pre-treatment levels by June 2022. This indicates that the species has successfully re-established in Gillsvann. Overall, this study demonstrates the potential effectiveness of rotenone treatment for eradicating invasive species and the utility of eDNA analysis for monitoring the possible success of eradication efforts and re-establishment of native species. | |
