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

The ontogeny of Dentex dentex (Linnaeus, 1758) was studied comparatively un der extensive and semi-extensive rearing conditions. The exotrophic phase w as divided into three distinct developmental stages (a) larval, from feedin g 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 chang es was expressed during the larval stage and integrated during the metamorp hosis stage. The juvenile stage was characterized by developmental stabilit y, The normal development of D. dentex was seriously affected by the rearin g conditions applied during the early exotrophic phase. The two differently reared populations followed similar developmental patterns of general morp hology, pigmentation and behaviour, but they presented high developmental p lasticity where allometric growth was concerned. Rearing conditions influen ced both the boundaries of the sequential stages (in 50% of the morphometri c ratios) and the allometry coefficient of each morphometric character in t he 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.