The morphology and morphometry of otoliths have emerged as powerful indicators of ecological characteristics of fishes. However, shape descriptors that can accurately predict well-documented functions played by species in tropical ecosystems are either restricted to a few groups or poorly known. Therefore, we evaluated the power of two otolith shape descriptors (ecomorphological indexes and Fourier harmonics) in discriminating trophic and depth strata preference groups of tropical fish species. Differences in otolith shape of ecological groups were visualized by linear discriminant analysis (LDA), and tested by a jack-knife cross-validation method and permutational multivariate analysis of variance (PERMANOVA) for both methods. Visually and statistically, both descriptors were good predictors of trophic groups and depth preference categories (PERMANOVA, p < 0.05). Overall jack-knifed classification success between both descriptors were very similar, with harmonics correctly classifying 90.38% of assigned trophic groups and 75.96% of given depth preference categories, against 82% and 56.25% of ecological indexes, respectively. Our results suggest that Fourier descriptors and ecomorphological indexes of otoliths should be used as functional traits in future studies, as otolith shape provides a wider range of ecological information regarding feeding habitat, mobility, substrate association and water column use.

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Background. Reproductive aspects of fishes are very useful in the development of management and conservation strategies of stocks. The information available on this subject, however, is very limited for tropical species, especially for those with low economic value, such as the barred grunt, Conodon nobilis (Linnaeus, 1758). This species is a common member of the family Haemulidae off the coasts of Brazil and it plays an important ecological role in coastal areas acting as a biological vector of organic matter. Thus, this study was intended to provide data on the reproductive parameters of C. nobilis to fill the gap in the existing knowledge. Material and methods. Reproductive traits of C. nobilis were estimated from 410 fish collected in the coast of Alagoas, during fishery surveys carried out between December 2009 and June 2012. Length-weight relations (LWRs) for males and females were calculated from the observed length and weight by regression analysis. Data on the maturity status were used to estimate the size at first maturity for females, males, and pooled sexes. The fecundity was assessed by the volumetric method, and information on the reproductive period was retrieved from the gonadosomatic and the reproductive activity indices. Results. Sex ratio differed between sexes with mature females being more abundant than males. Although no evidence of sexual dimorphism was found in the length distribution, LWRs showed that males have a negative asymptotic growth and females present a positive asymptotic growth. The first sexual maturity for females, males, and pooled sexes was attained at 20.78, 20.57, and 20.72 cm of the total length (TL), respectively. Gonadosomatic and reproductive activity indices indicated that C. nobilis may be capable of spawning all year round with a more intense activity occurring between the rainy season in the region studied. The batch fecundity fluctuated between 1640 and 105 471 oocytes with a mean of 45 384 ± 16 737 eggs per female and was positively correlated to female size. Conclusions. Overall, C. nobilis showed an intermediate fecundity rate with reproductive activity throughout all year round. No evidence of sexual dimorphism in maturity and size distribution was found for the species. We hope that our findings may be helpful for fishery biologists in the design of effective management strategies for this ecologically important species.