Master 2 Internship

Most marine fishes have a bipartite life cycle, with a pelagic and dispersing larval phase followed by more sedentary juvenile and adult phases within coastal habitats. Research from our group showed that the transition from the larval to the juvenile phase, called larval recruitment, coincides with a metamorphosis controlled by thyroid hormones (TH). During metamorphosis, larval fishes undergo rapid and major morphological, physiological, and behavioral changes that are critical for their survival in the juvenile populations within coastal habitats.

Within this generalized marine fish life cycle framework (i.e., “classical life cycle”), the spiny chromis Acanthochromis polyacanthus stands as an exception, as it possesses very peculiar life-history traits. Indeed, the spiny chromis does not exhibit a dispersive pelagic larval stage. Instead, adults lay large eggs in a nest that they guard, and after 15 days of incubation, newly hatched individuals stay in the vicinity of the nest where parents continue to protect them. It’s only ~ 3 months after hatching that parents will chase their offspring which will settle in a nearby reef. Moreover, at hatching, the spiny chromis already display quite advanced morphological and behavioral traits in comparison with other species with a more classical life cycle, suggesting that many of the changes normally occurring during post-embryonic development in other species may occur during incubation (i.e., embryonic development) in the spiny chromis. This species is thus a particularly relevant model to evaluate the effects of multiple stressors on the biology, development, and physiology of reef fish early life-stages.