Effect of vitamin A on the skeletal morphogenesis of European sea bass,Dicentrarchus labrax (Linnaeus, 1758)

The purpose of this study was to examine the effects of vitamin A levels in the larval diet of Dicentrarchus labrax, (a) on the shape of juvenile skeleton and (b) on the development of pelvic fins. To exclude the side‐effects of skeletal abnormalities on skeleton shape, morphometric analysis was performed on normal individuals only. Geometric morphometric analysis revealed a significant effect of larval nutrition on the shape of juvenile skeleton (Wilk's λ=0.0188, P<0.001), 55 days after the application of the different nutritional regimes. Between‐groups shape differences mainly concerned the position of anterior dorsal pterygiophore, which was associated with a significant (P<0.05) increase of the number of dorsal lepidotrichia and hard spines at low levels of vitamin A (3–9 × 10³ IU kg^?1 dry food). At the lowest vitamin A levels (3 × 10³ IU kg^?1 dry food), the development of pelvic fins was abnormal, with severe bilateral (44±10%, mean±SD) or unilateral (22±9%) lack of the fin lepidotrichia, hard spines and their supporting elements. In the 82–94% of the unilaterally deformed individuals, deformation concerned the left pelvic fin. Concerning the shape of pelvic fins in the normally developed individuals, results demonstrated a significant effect of nutritional conditions on the size and position of all the elements of the pelvic fin area (basipterygium, lower metacleithrum, cleithrum, scapula) (Wilk's λ=0.3087, P<0.001). Our results demonstrate a significant nutritionally driven phenotypic plasticity in D. labrax, with dietary levels of vitamin A determining the skeleton shape and the left–right symmetry of pelvic fins.