Towards a Characterization of the Locomotor Activity Rhythm of the Supralittoral Isopod Tylos europaeus

Biological Rhythm Research

Nasri–Ammar

2014

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Locomotor activity rhythm of Orchestia montagui and Orchestia gammarellus was investigated in populations from the supralittoral zone of Bizerte lagoon. The rhythm was recorded in individual animals in spring, firstly under continuous light with two simultaneous luminous intensities (5 and 140 lux) and secondly under continuous light with four different luminous intensities (5, 35, 75, 140 lux). Thirty specimens were tested for each experiment and for each species. Results revealed that whatever the species and the luminous intensity imposed, actograms showed a clear drift to the right lengthening the circadian period day after day. On the other hand, under continuous light with different luminous intensities, circadian periods determined by periodogram analysis decreased with increasing of luminous intensity for O. montagui whereas for O. gammarellus, circadian period lengthened with increasing of luminous intensity. Concerning ultradian period, it increased with luminous intensity whatever the species studied. Moreover, the stability was important under 5 lux for O. montagui and 140 lux for O. gammarellus. In addition, the study of the mean activity times calculated for these two species showed that the most important activity of individuals was observed under 75 lux for O. montagui and under 140 lux for O. gammarellus.

Section: Discussionmentioning

confidence: 57%

Effect of light intensity on the locomotor activity rhythm ofOrchestia montaguiandOrchestia gammarellusfrom the supralittoral zone of Bizerte lagoon (North of Tunisia)

Biological Rhythm Research

Nasri–Ammar

2014

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“…The present study highlighted the existence of a circadian component controlling the (Bohli-Abderrazak et al 2012) showed that the nLD cycle acts as the most efficient zeitgeber setting the phase of the animal's circadian rhythm adequately to the environmental 24h periodicity. Thus, under continuous darkness each animal expresses its own rhythm.…”

Section: Discussionmentioning

confidence: 95%

“…Statistically, differences between percentages were analyzed by χ2 test, and differences between all mean values were calculated using the non-parametric Kruskal-Wallis rank test (Nasri & Morgan 2005aBohli-Abderrazak et al 2012).…”

Section: Methodsmentioning

confidence: 99%

“…Prabhakaran & Sheeba (2012) explained this bimodality in Drosophila melanogaster as a need to minimize the effects of environments at other harsher times of the day. Bohli-Abderrazak et al (2012) showed that the bimodality observed in Tylos europaeus collected from Korba beach was associated with a single bout of nocturnal activity, and may be of a crepuscular nature. The same authors (2006) observed the bimodality under entraining conditions; this result can be explained by the abrupt light-dark transitions at both experimental dusk and dawn.…”

Section: Nasri-ammar and Morganmentioning

confidence: 98%

“…Among the three species, Britorchestia brito and Tylos europaeus are still poorly investigated in many aspects and their circadian activity, apart from the study of Bohli-Abderrazak et al (2012) in Tylos europaeus, were almost unknown so far. Despite the works of Jelassi et al (2013b) and Ayari & Nasri-Ammar (2012b) highlighting the interspecific competition between Orchestia montagui and Orchestia gammarellus on the one hand and between Deshayesorchestia deshayesii and Talitrus saltator on the other hand, little attention have been paid to the fact that differences in circadian activity can be an efficient mechanism diminishing interspecific competition and partitioning resources.…”

Section: Introductionmentioning

confidence: 99%

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

Biological Rhythm Research

Nasri–Ammar

2015

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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

Khemaissia

Microscopy Res & Technique

et al. 2021

Effects of trace elements on the hepatopancreas ultrastructure and on the locomotor activity rhythm were investigated in the amphipod talitrid Orchestia gammarellus collected from Bizerte lagoon banks situated in the north of Tunisia. Animals were exposed to a series of contaminated soil with different concentrations of cadmium and zinc. The locomotor activity rhythm was studied under constant darkness. Histopathological analysis showed that the trace elements, especially the Cd, induced significant changes in the morphology and in the ultrastructural organization of hepatopancreatic cells. The significant alterations obtained were dose dependent. Concerning the behavioral response, results revealed the presence of two components whatever the experimental conditions. In addition, a great inter‐individual variability of the locomotor rhythm was observed. Patterns were in majority bimodal for the control individuals and became unimodal and multimodal when exposed under Cd and Zn, respectively. Furthermore, ultradian and circadian periods were determined. The circadian period lengthened after Zn exposure. In addition, the locomotor activity rhythm was more stable for control individuals. However, those exposed to Cd were less active.