Effect of social synchronization on the locomotor activity rhythm of the amphipod Talitrus saltator from Korba population (Gulf of Hammamet, Tunisia)

Abstract

The locomotor activity of the Amphipod Talitrus saltator, collected from Korba beach (Gulf of Hammamet, Tunisia), was recorded individually as well as in groups under two simultaneous regimens: the light/dark cycle and the constant darkness. Results obtained for this species showed a nocturnal behavior whatever the recording type and the regimen imposed. In addition, the locomotor rhythm is controlled by a circadian component close to 24 hours with a mean value shorter in groups than in isolated individuals. These last are less active and describe a less stable locomotor rhythm. The analysis of the different locomotor activity parameters showed that the inter-group variability is less important than the inter-individual variability highlighting thus the effect of the group in the attenuation of this variability. This result is confirmed by the analysis of the phase shift which is a near-zero for groups.