Résumé
High dietary levels of arachidonic acid (ARA) and its relative proportions with eicosapentaenoic acid (EPA), fed during early larval stages, have been associated with malpigmentation in various flatfish species. This study investigated whether the nutritional induction of pigmentary disorders at larval stages was related to a specific larval period of increased sensitivity to ARA in Senegalese sole (Solea senegalensis Kaup, 1858). Senegalese sole larvae were fed high dietary ARA levels during pre- and pro-metamorphosis (2–15dph) and/or post-metamorphosis (15–50dph). Larval tissues reflected the dietary fatty acid composition. Malpigmentations were significantly related to elevated dietary and larval ARA contents and ARA/EPA ratio. This study reports evidence for a “pigmentation window”, with a higher larval sensitivity to dietary ARA during pre- and pro-metamorphosis than post-metamorphosis. High dietary ARA fed to larvae during pre-metamorphosis enhanced survival, but did not affect growth nor eye migration. The aspect and density of melanophores in the skin of the ocular side of ARA-induced pseudo-albinos were significantly reduced in comparison to normally pigmented individuals, even more in the pseudo-albino fish fed high dietary ARA levels during the pre-metamorphic stage. Pseudo-albino fish fed high dietary ARA levels during post-metamorphosis showed higher concentrations of 2- and 3-series prostaglandins (PGE2 and PGE3) than normally pigmented specimens fed the same diets. An increased sensitivity to ARA-induced malpigmentations has been identified at pre-metamorphosis and early metamorphosis in Senegalese sole. Supplying high dietary ARA amounts imbalanced the dietary ARA/EPA ratio and disrupted the relative concentrations of derived PGE2 and PGE3, resulting in 20 to 81.7% pseudo-albino individuals, depending on the dietary treatment. The administration of high levels of dietary ARA at different developmental stages did not only affect the incidence of animals with pigmentary disorders, but it also affect the melanophore density and skin aspect in normally pigmented and pseudoalbino fish as image segmentation and texture analyses indicated.
•Pigmentary disorders were related to high dietary and larval ARA and ARA/EPA levels.•ARA-induced pseudoalbinism is a developmental-dependent phenomenon.•Fish were more sensitive to ARA and ARA/EPA levels at pre- and pro-metamorphic stages.•High ARA levels imbalanced the ARA/EPA and affected the production of PGE2 and PGE3.•Dietary ARA levels affected melanophore density and skin aspect.