Application of otolith morphometry for the study of ontogenetic variations of Odontesthes argentinensis

Abstract

The study of otolith morphometry is a tool widely used in numerous studies of fish populations (fish stocks, taxonomic, ecological, ontogeny, among others). The aim of this study was to detect ontogenetic variations in the otolith of Odontesthes argentinensisthrough the application of traditional and geometric morphometry and the association of these variations with ecological and trophic habits of the species. Fish (52 to 360 mm TL) were collected seasonally between years 2013?2016 in the southwest coast of the AtlanticOcean (36°39?30.96?S - 56°40?40.09?W). Otolith shape indices (circularity, rectangularity, aspect ratio and surface occupied by sulcus) and Fourier descriptors were measured and compared through ontogenetic stages (I, II and III). The three stages analysed in thepresent study were differentiated by both traditional and geometric morphometry. The four analysed indices showed significant differences between stages (ANOVA KruskalWallis test, P < 0.001) and a simultaneous analysis of the morphometric variables also showed significant differences (Hotelling?s T2 < 0.001). The quadratic discriminant analysis performed on the Fourier descriptors showed a clear separation for each defined group. Therefore, the use of both methodologies simultaneously could be considered robust toevaluate the ontogenetic variations in this species. The observed changes could be associated to changes in the habitat throughout its development, to the sexual maturityof fish and to dietary shifting of these organisms.