Relative growth of Menippe frontalis (Crustacea: Brachyura) in the Gulf of Guayaquil, Ecuador, by multi-model approach

Abstract

Relative growth can help to identify dimorphism between individuals, and it is also used to determine changes in ontogeny related to sexual maturity. The morphometric variables recorded were width, length and height in carapace and chelae. The abdomen width was taken only in females. Data analysis was made separating males and females. Exploratory analysis used maximum, minimum and mean values and compared these values between sexes using MANOVA, ANOVA and LSD-Fisher methods. A weight-size relationship was also determined. Relative growth was estimated using a multi-model approach. Six models were applied, and the best was selected using Akaike and Bayesian information criteria. Residual versus predicted graphics were also produced based on the selected models. The mean sizes were similar between sexes, but the maximum values were observed in males. The weight-size relationships showed a negative allometry. The best model varied by morphometric variables and sex, but the type of relative growth was principally isometric and negative allometry. Biometric characteristics in Menippe frontalis A. Milne-Edwards, 1879 did not show abrupt changes in the relative growth. The threshold was not assumed as an indicator of morphometric sexual maturity however, they may be used for establishing legal minimum size in M. frontalis.