Ontogeny and allometric plasticity of Dentex dentex (Osteichthyes: Sparidae) in rearing conditions

Abstract

The ontogeny of Dentex dentex (Linnaeus, 1758) was studied comparatively under extensive and semi-extensive rearing conditions. The exotrophic phase was divided into three distinct developmental stages (a) larval, from feeding onset up to 10 mm total length (TL); (b) metamorphosis, from 10 mm TL up to 24 mm TL; and (c) further juveniles. The majority of all ontogenic changes was expressed during the larval stage and integrated during the metamorphosis stage. The juvenile stage was characterized by developmental stability. The normal development of D. dentex was seriously affected by the rearing conditions applied during the early exotrophic phase. The two differently reared populations followed similar developmental patterns of general morphology, pigmentation and behaviour, but they presented high developmental plasticity where allometric growth was concerned. Rearing conditions influenced both the boundaries of the sequential stages (in 50% of the morphometric ratios) and the allometry coefficient of each morphometric character in the various developmental stages (in 80% of the characters). The results are discussed with respect to the ontogeny of the functional morphology under both ecological and aquaculture considerations.