Natural Analogues of Climate Change Can Reveal Fish Responses Across Multiple Levels of Biological Organisation

ABSTRACT Anthropogenic climate change is threatening ecosystem functionality and biodiversity globally. While significant research has been dedicated to understanding how organisms may respond to future climate change, most of these studies focus on individual levels of biological organisation in controlled laboratory settings, which often fail to capture the complexity of natural ecosystems. Organisms respond to climate stressors across various levels of biological organisation, which also involve complex interactions or feedback mechanisms among levels, making it difficult to generalise responses to climate change from laboratory experiments or single levels alone. Natural analogues provide a unique opportunity to observe complex ecological interactions in real‐world environments with long‐term exposure to climate change stressors. Here, we provide a systematic literature review to reveal how natural analogues of ocean warming and ocean acidification can be used to assess fish responses to climate change across multiple levels of biological organisation (from molecular to biogeographical scales) and to assess how cross‐level buffering and feedback mechanisms may shape fish species persistence in a future ocean. We identify key knowledge gaps and propose research frameworks that integrate natural analogues with laboratory experiments, mesocosms, and predictive models to better capture the complexity of fish responses to climate stressors in a more holistic way. Finally, we highlight the importance of coordinated, cross‐system research using multiple natural analogues to reveal adaptive mechanisms and strengthen predictions of fish community reorganisation under climate change.