Improving North Sea biodiversity monitoring using novel molecular approaches

The North Sea is one of the most productive seas, supporting diverse marine life, yet it faces increasing pressure from fishing, offshore industry and development. To understand the effects of offshore development on marine life, frequent, accurate and efficient biodiversity monitoring is needed, and this monitoring should be scalable. This thesis explores how environmental DNA (eDNA) metabarcoding can improve biodiversity monitoring of fish and invertebrates to support conservation management in the North Sea. Across the thesis, new molecular methods were developed using Oxford Nanopore sequencing and tested in natural biogenic reefs, shipwrecks, and offshore wind farms. The research shows that Nanopore-based metabarcoding approaches perform similarly to conventional methods, while long-read and RNA approaches can provide additional species resolution and community insights. eDNA-based biomonitoring of natural shellfish reefs also showed that these reefs support richer fish communities, including commercially important species. This thesis demonstrates that advanced DNA-based techniques are a promising non-invasive monitoring method for improving marine management and decision-making.