The silent signals of climate change

Climate change is transforming marine ecosystems in visible and stark ways, such as the bleaching of coral reefs. Yet, subtler though similarly profound disruptions are also happening to the chemical ecology of the ocean. These invisible changes are understudied and absent from most climate change models but may play fundamental roles in structuring future ocean ecosystems. On page 876 of this issue, Farrell et al. (1) show that climate-driven shifts of kelp forests into “turf algae” (carpets of filamentous red algae) alter the chemical environment of temperate reefs, making them less hospitable to young kelp. These findings indicate that climate change is not just reshaping physical habitats but also disrupting the chemical interactions that underpin key biological processes, which could have important implications for marine conservation efforts.