Endogenous activity rhythm inTalitrus saltator,Britorchestia brito(Crustacea, Amphipoda) andTylos europaeus(Crustacea, Isopoda) from Barkoukech Beach (Tabarka, Tunisia)

Abstract

The locomotor activity rhythm of three supralittoral crustacean species, Tylos europaeus (terrestrial isopod) and Britorchestia brito and Talitrus saltator (amphipod, Talitridea), was investigated in Barkoukech Beach. The rhythm was monitored in individual animals in spring under continuous darkness and constant temperature.Results revealed that whatever the species, actograms and mean activity curves showed that specimens of Tylos europaeus and Talitrus saltator concentrated their activity during the subjective night; whereas, Britorchestia brito concentrated its activity during the subjective day. The three species exhibited a circadian locomotor rhythm with mean circadian period respectively equal to 24h41'±0h44', 24h46'±0h55' and 25h21'±1h16'.The most stable locomotor rhythm was found in Talitrus saltator (0.444±0.246).Furthermore, individuals of Tylos europaeus were significantly more active (10h47'±2h52') than the two amphipods.Differences in the activity patterns of the three species will be discussed as an adaptative strategy to respond to interspecific competitive interactions.

Physiological and behavioral responses of Orchestia gammarellus (Amphipoda, Talitridae) towards trace elements contamination soil

“…The nocturnal behavior characterized the majority of amphipods and terrestrial isopods species (Bregazzi & Naylor, 1972;Williams, 1980;Nasri-Ammar & Morgan, 2005;(Bohli-Abderrazek, Jelassi, Morgan, & Nasri-Ammar, 2019;Bohli-Abderrazek, Jelassi, Morgan, & Nasri-Ammar, 2020;Bohli-Abderrazak, Ayari, Morgan, & Nasri-Ammar, 2012). This behavior was essential for the survival of some species such as Talitrus saltator that required a relative humidity more than 80% (Bohli-Abderrazek et al, 2019;Bohli-Abderrazek et al, 2020;Williamson, 1951) as well as Tylos europaeus (Bohli-Abderrazak, Ayari, Morgan, & Nasri-Ammar, 2012, Jelassi, Bohli-Abderrazak, Ayari, & Nasri-Ammar, 2015 that needed low temperatures allowing it to improve its oxygen consumption (Marsh & Branch, 1979).…”