European waters have recorded their hottest summer, with rising temperatures affecting marine habitats and species. The Bay of Biscay experienced a significant temperature rise, with marine heatwaves extending throughout the season. Kelp forests in northern Spain have sharply declined, impacting local marine ecosystems. Additionally, octopus populations are surging in southern England, affecting traditional fishing yields. Non-native species are also expanding into the Mediterranean, altering local food chains and competitive dynamics.