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Ecomorphological patterns in otoliths of tropical fishes: assessing trophic groups and depth strata preference by shape


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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We would like to thank colleagues Carol Passos, Marcia Sousa, Rosa Costa and Vandick Batista for their assistance during field and laboratory work, and Richard Ladle for checking the English of the manuscript. This research was funded by the Brazilian National Council for Scientific and Technological Development – CNPq (N. Fabré, grant #306624/2014-1) and the Coordination for the Improvement of Higher Education Personnel – CAPES. Data collection and analysis was funded by a grant from the State Funding Agency of Alagoas (FAPEAL) and the Brazilian Ministry of Fisheries and Aquaculture (MPA). The research was carried out in accordance with the principles of the Basel Declaration and following the recommendations of the Brazilian Animal Protection Law. All procedures were approved by the System of Biodiversity Authorization and Information (SISBIO committee) under the license #13392.

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Correspondence to Victor E. L. da Silva.

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Assis, I.O., da Silva, V.E.L., Souto-Vieira, D. et al. Ecomorphological patterns in otoliths of tropical fishes: assessing trophic groups and depth strata preference by shape. Environ Biol Fish 103, 349–361 (2020).

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  • Ecological indicators
  • Feeding habit
  • Functional diversity
  • Sagittae
  • Surrogate