When are mangrove crabs fat? Seasonal and sexual variation in the fatty acid composition of edible crab species Ucides cordatus from the Brazilian Amazon coast

Abstract

Fatty acids play important role in several biological processes taking place in crustaceans, such as reproduction and molting. The aim of the current study is to evaluate the seasonal variation in fatty acid concentration and profile in crab species Ucides cordatus exploited in Brazilian mangroves. Eight samplings were performed throughout one year and 30 adult specimens - 15 males and 15 females - were selected - it totaled 240 individuals. Muscle and hepatopancreas were freeze-dried and had their fatty acid profiles analyzed through gas chromatography. Analysis of variance, principal component analysis and cluster analysis were carried out in order to find patterns among sample groups. Sixteen fatty acids were found in hepatopancreas; palmitic acid presented the highest concentration in male (22.25–33.72%) and female individuals (24.97–31.74%). On the other hand, five fatty acids were identified in muscle tissues - linoleic acid was the fatty acid recording the highest concentration in male (20.51–27.49%) and female individuals (21.62–28.05%). Based on multivariate analysis, fatty acid concentrations played major role in group formation. With respect to the hepatopancreas, reproduction and pre-ecdysis phases were more clearly distinguished for female than for male individuals. Higher fatty acid concentrations were found in the muscles of the pos-ecdysis group. Overall, fatty acid concentrations have shown different behaviors for both tissues and for both sexes - the main variations were observed during the breeding and intermolt phases.