A detailed morphological, behavioural, and genetic characterization of the larval phase of the Red Sea clownfish, Amphiprion bicinctus

• Main Author: Justo, Micaela
• Other Authors: Berumen, Michael L.
• Language: en
• Published: 2021
• Subjects: Coral reef fish; Clownfish; Developmentak stages; Ontogeny; Dispersal pelagic larval phase; Settlement phase
• Online Access: Justo, M. (2021). A detailed morphological, behavioural, and genetic characterization of the larval phase of the Red Sea clownfish, Amphiprion bicinctus. KAUST Research Repository. https://doi.org/10.25781/KAUST-05J02; http://hdl.handle.net/10754/669003

Coral reef fish are known to have a bipartite life cycle: a dispersive pelagic larval phase (DPL), where larvae ‘travel’ away from their parents to occupy new habitats, and a sedentary reef phase characterized by juveniles and adults. Study of the DPL is an essential prerequisite to understand how persistence, connectivity, and gene flow operate between populations. Clownfish have been the subject of considerably varied fields of research in recent decades, not only due to their economic value, but also because of their ease of maintenance in laboratory settings, regular spawning, and short DPL. Their life cycle is also defined as bipartite, with a DPL lasting around 15 days until settlement, and the fish exhibit a symbiotic relationship with sea anemones. The transitions between phases are associated with a series of morphological, behavioural, genetic, cellular and molecular changes. However, these changes are poorly characterized in some species of clownfish. Therefore, the Red Sea clownfish, Amphiprion bicinctus, was reared to fill the gap in the literature by investigating their i) morphology, ii) swimming abilities, and iii) differential gene expression (DGE) throughout ontogeny. The DPL was characterized in the preflexion, flexion and postflexion stages, according to flexion of the notochord, on 0, 2 and 10 days post hatch (dph), respectively. Metamorphosis was defined by a morphological transition between the DPL and juvenile phases, associated with the appearance of white stripes, on day 10 and until the end of the experiment, on day 14. Additionally, metamorphosis is followed by a behavioural change at 14 dph, called settlement, where larvae transition from free swimming in the water column to associating with the substrate. We also demonstrate that the larvae present active swimming from the moment they hatch, and the swimming speed increases throughout DPL. Overall, the development of A. bicinctus is similar to other clownfish species. This work provides a strong baseline on the development of A. bicinctus, which may open the door to a deeper understanding of the role of dispersal behaviours and enhance our ability to design effective marine reserve networks in the Red Sea.