FRAMES

Most marine fishes have a bipartite life cycle with a pelagic larval stage followed by reef-associated juvenile and adult stages. The return, settlement, and survival of larval fishes in reefs is referred to as larval recruitment, one of the most critical and endangered life-history transition in vertebrates. It usually coincides with the larva to juvenile metamorphosis, during which fish undergo various morphological, physiological, and behavioural changes. Recent research demonstrated that metamorphic changes are controlled by endocrine systems whose disruption can diminish juvenile fish survival and impact larval recruitment success. However, this knowledge is limited to a few species while marine fishes actually exhibit an outstanding diversity of larval recruitment strategies and associated metamorphic changes of variable magnitudes and timing. I hypothesize that species whose larval recruitment strongly rely on substantial and timely metamorphic changes orchestrated by disruptable hormonal pathways would be more impacted by climate change and pollutions. In multiple species displaying a broad range of larval recruitment and metamorphosis strategies, FRAMES will examine how neuroendocrinology and ecophysiology translate into specific fish phenotypes through functional experiments and by developing cutting-edge computer vision and deep-learning methods to record standardized morphological and behavioural data. The vulnerability of each strategy to endocrine disruption will be examined by experimental exposure to multiple stressors ranging from chemical pollutants to increased temperatures. This unique multispecies and integrative framework, from gene expression to behavioural ecology, will allow to outline the evolutionary routes of fish larval recruitment and metamorphosis strategies, elucidate the inner mechanisms responsible for their diversity, and shed light on their vulnerability through novel and non-destructive ecotoxicological approaches.