Mise en évidence de l’endogenie du comportement locomoteur d’Orchestia gammarellus (Crustacea : Amphipoda ; Talitridae) en situation d’allopatrie

Abstract

The locomotor activity rhythm of Orchestia gammarellus population collected from Ghar El Melh lagoon banks was recorded in individual specimens under constant darkness over four seasons. Results revealed that the highest mortality was determined in winter. Double-plotted actograms obtained showed the presence of a clear drift to the right; this drift was well pronounced in summer. In addition, an interindividual variability of locomotor rhythm was observed whatever the season, showing thus the presence, in majority, of the multimodal patterns. Furthermore, ultradian and circadian components were observed over the seasons. Individuals of O. gammarellus were statistically less active in summer. However, during this season, the locomotor activity rhythm was more stable and well defined.