Three years after installation at Vattenfall’s Hollandse Kust Zuid wind farm in the North Sea, monopile foundations with water-venting holes were found to contain distinct marine communities—including sponges, sea squirts, brittle stars and tube-building worms—while exteriors were dominated by mussels and anemones. The 2024 JIP-LIFE study surveyed five monopiles using video, eDNA, water-quality measurements and computer models, and noted microbial mats on the seabed inside indicating localised oxygen depletion. The consortium’s final report was released by Deltares, Wageningen Marine Research, Seaward, Vattenfall and the article’s source, funded by Topsector Offshore Energy.