Social status and individual behavioral differences in juvenile Macrobrachium rosenbergii

Abstract

Adult Macrobrachium rosenbergii males appear in three distinct morphotypes associated with dominance hierarchy. Juveniles can also differ but only in body size. We examined whether juveniles present a size-related dominance hierarchy and whether it could be related to individual behavioral profile. Behaviors were recorded in groups of four prawns for 30 days in the laboratory, four times during light and dark phases of the 24 h cycle. Dominance ranks were analyzed using David’s score method. Observed behaviors differed between light phases. In most groups, two individuals obtained a positive score and the other two a negative score; they were therefore considered dominants and subordinates, respectively. There was no correlation between dominance and general behavioral activities. Dominants had greater weight gain and faster access to food. The precocious relation between growth and dominance suggests dominant juveniles are more likely to become blue claw adult males, the morphotype with greater reproductive success.

Keywords:

• prawn
• Macrobrachium rosenbergii
• juvenile
• agonistic behavior
• activity profile
• dominance hierarchy
• feeding
• growth

Acknowledgements

We would like to thank the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), the Coordenação de Aperfeiçoamento de Pessoal de Nível superior and the Department of Physiology of the Universidade Federal do Rio Grande do Norte for their support in developing this study.