Tenebrionidae beetles are a conspicuous element of most arid and semi-arid environments. In this paper, the two sympatric darkling beetles' species Erodius emondi (N = 21) and Pimelia grossa (N = 21), collected from the coastal dunes of Korba, are chosen to characterize their locomotor activity rhythm under laboratory conditions under natural light–dark cycle then under constant darkness. Our results highlighted the existence of diurnal behaviour for both species with the presence of ultradian and circadian components, whatever the experimental conditions. These two species exhibited in majority multimodal activity patterns under entraining conditions. Under constant darkness, we noted the appearance, in addition to the multimodal profile, the unimodal and bimodal ones for E. emondi and P. grossa respectively. The specimens of this last species were statistically more active displaying also the most important stability of their locomotor rhythm compared to those of E. emondi. The obtained results will be discussed in relation to their temporal niches segregation.

The Bizerte lagoon is a highly productive coastal ecosystem, yet it faces constant pressure from human activities and exposure to Zinc. This study compared Zn bioaccumulation in three Orchestia species (Orchestia gammarellus, Orchestia montagui, and Orchestia mediterranea) collected from the lagoon's banks. Individuals were exposed to contaminated soil with three different zinc concentrations, and their biological and physiological responses were assessed. Body zinc concentrations were measured using flame atomic emission spectrometry. Results showed a significant increase in mortality by the second week of exposure, alongside notable differences in body mass variations between species. O. mediterranea exhibited greater resilience to zinc exposure. Zinc accumulation in the Orchestia species was considerably higher than in the surrounding sediment, classifying all three species as macroconcentrators of zinc. Additionally, zinc-contaminated substrates induced structural changes in the amphipods' hepatopancreas, considered as the efficient storage organ, with the most pronounced alterations occurring at the highest zinc concentrations. In O. gammarellus, ultrastructural changes included lipid granules of varying shapes and sizes, while O. montagui and O. mediterranea displayed disrupted cell borders and swollen mitochondria. This study highlights the sensitivity of Orchestia species to zinc contamination, confirming their potential as bioindicators of metal pollution in coastal environments.

In the context of climate change, Tunisia is particularly concerned about global warming. Moreover, Tunisia has a high reliance on agriculture and mass tourism, which are two very water-intensive sectors. Consequently, understanding and evaluating the only permanent river in Tunisia, the Medjerda River, is crucial. An innovative and multidisciplinary approach to contribute to a biosurveillance network along the Medjerda Valley is needed to diagnose the health status of Medjerda wadi. This work aimed to contribute to the establishment of a biosurveillance network along the Tunisian section of the river. To execute this, we focused on the meiofauna along the upstream and downstream continuum of Medjerda River between the Ghardimaou Heights and the Kalaat El Andalus delta area, which represents a distance of 217 km from our first station to our last station. We aimed to determine some bioindicator species that could be used to establish a biosurveillance network based on meiofauna taxa and, especially, free nematodes. Various techniques were used, among them the use of a core barrel. Six stations were chosen: three in the upper valley and three in the downstream part. The preliminary results show relatively oxygenated water with organochlorine pesticide (OCP) levels below the threshold of 1 µg/l and hydrocarbon levels under 0.1 mg/l. The conductivity is higher downstream than upstream; the same is true of the total dissolved solids (TDS) and the salinity. However, the degree of oxygenation is higher in the upper valley than in the lower valley. Additionally, preliminary results for the meiofaunistic composition show a large predominance of nematofauna among other taxa.

The crested porcupine is an invasive species in Italy with a growing population and an expanding range. Whilst the species is mainly nocturnal, it has been observed diurnally throughout the year in Italian habitats. Research has attributed these observations to foraging requirements in daylight hours especially in periods when nights are shorter and primary production is more limited. This implied that crested porcupines are under trophic and physiological stress in Italy, which contradicts with their observed demographic and spatial expansion. Here we use data collected over 30,765 camera days by camera-trap grids within the species' indigenous range in two Tunisian semi-arid national parks where primary productivity is limited. We postulated that if the foraging hypothesis was accurate, we would record diurnal activity of crested porcupines in our resource-scarce study sites as the species increases active foraging hours to fulfil its trophic requirements. Analyses however revealed exclusively nocturnal activity patterns in the studied sites in Tunisia, thus contrasting with the foraging hypothesis. Our results indicate that the species is not under stress in Italian ecosystems and diurnal mobility is likely limited to basking, grooming, etc. in the near vicinity of burrow entrances.

The highly persecuted African houbara (Chlamydotis undulata undulata) is thought to persist in Tunisia's arid-lands. Recent reports have, however, failed to observe the species and concluded that it was on the verge of extinction. We deployed camera-traps in three of Tunisia's national parks (NPs) that were sites for large scale habitat restoration and mega-herbivore reintroductions. Sampling was for 20,382 camera days in Dghoumes NP, 14,377 in Jbil NP and 4,006 in Sidi Toui NP. We report one observation of the African houbara in Sidi Toui NP and highlight the benefits of mega-herbivore conservation for the wider biodiversity of the region.

The order Isopoda contains both aquatic and terrestrial species, among which Hemilepistus reaumurii, which lives in arid environments and is the most adapted to terrestrial life. Olfaction has been deeply investigated in insects while it has received very limited attention in other arthropods, particularly in terrestrial crustaceans. In insects, soluble proteins belonging to two main families, Odorant Binding Proteins (OBPs) and Chemosensory Proteins (CSPs), are contained in the olfactory sensillar lymph and are suggested to act as carriers of hydrophobic semiochemicals to or from membrane-bound olfactory receptors. Other protein families, namely Nieman-Pick type 2 (NPC2) and Lipocalins (LCNs) have been also reported as putative odorant carriers in insects and other arthropod clades. In this study, we have sequenced and analysed the transcriptomes of antennae and of the first pair of legs of H. reaumurii focusing on soluble olfactory proteins. Interestingly, we have found 13 genes encoding CSPs, whose sequences differ from those of the other arthropod clades, including non-isopod crustaceans, for the presence of two additional cysteine residues, besides the four conserved ones. Binding assays on two of these proteins showed strong affinities for fatty acids and long-chain unsaturated esters and aldehydes, putative semiochemicals for this species.

Saharan ungulates have suffered from poaching across their range leading to population declines. Low abundance and habitat inaccessibility have limited the availability of empirical data on desert ungulate ecology in the wild. Our objective was to evaluate temporal and spatial distribution, and home-range sizes of wild dorcas gazelles (Gazella dorcas) and slender-horned gazelles (Gazella leptoceros) under natural conditions using observations from 14,398 camera-days collected between April 2019 and October 2021 in the 7,700-ha fenced area of Jbil National Park (Jbil NP), Tunisia. We individually identified gazelles in Jbil NP using unique horn morphology. Both gazelle species exhibited nocturnal activity patterns in summer, but diurnal activity patterns dominated in winter. We also detected both species more frequently in the plains than in mountains. Water presence was influential in determining distribution only for dorcas gazelles. Minimum convex polygons (MCPs) were 2,062 ha for both the male and female of the most frequently detected dorcas gazelle pair and 1,527 ha for another solitary male. For slender-horned gazelles, MCPs were 2,280 ha and 2,041 ha, respectively, for a male and a female detected in Jbil NP. The decline and rarity of gazelles in the Sahara Desert have limited the sample size of our observed populations. Our study provides hitherto unknown data on wild populations of rapidly declining gazelle species and contributes to ongoing conservation efforts.

North Africa's megafauna has developed behavioural adaptations to reduce energetic and fitness costs under harsh arid land conditions. Animal behaviour and activity patterns are difficult to study in the wild, but remote camera traps provide a solution to collecting data without the presence of a researcher influencing outcomes. Here, we report results from a study comprising over 20,382 camera-trap days during a 34-month period in Dghoumes National Park, Tunisia. We aimed to evaluate temporal activity patterns and their overlap and explore opportunities for niche partitioning. Our focal species were the reintroduced scimitar-horned oryx, north-African ostrich, dorcas gazelles and extant regional top-order predators, African wolf and red fox. We found differences in activity patterns between seasons across the focal species, with the most noticeable change being an increase in dawn activity from 1% to 33% between winter and summer for the red fox. Consequently, higher summer temperatures limit opportunities for temporal niche partitioning and push focal species towards dawn-time activity peaks resulting in higher intra-guild overlap values at dawn. Arid antelopes have physiological adaptations that enable them to better exploit ecological resources in hotter time periods than the carnivores, and this reduces inter-guild overlap during summer days.

The aim of this study was to test the effect of two tagging product on the locomotor rhythm parameters of individuals of the desert isopod Hemilepistus reaumurii collected from the marginal zone of a salt lake in Bchachma (Middle of Tunisia) in laboratory-controlled conditions. Results showed that locomotor activity of control individuals (CI) and individuals tagged with oil painting (IOP) was very similar highlighting sensitivity to dawn and dusk, respectively. Further, results showed that CI locomotor rhythm was statistically more stable than that of IOP and individual tagged with nail polish (INP). Additionally, individuals tagged with nail polish (INP) were more active than CI and IOP. This could highlight the effect of this last marking product on the locomotor rhythm parameters of H. reaumurii.

This study deals with the impact of zinc on the locomotor activity rhythm of two terrestrial isopods Armadillo officinalis and Chetophiloscia elongata. Specimens are collected from the banks of Ghar El Melh lagoon. The locomotor rhythm of untreated and treated individuals with zinc is studied in the laboratory under constant darkness for 10 days. Results showed that untreated individuals of A. officinalis and C. elongata exhibited nocturnal behavior. After Zn exposure, these species concentrated their locomotor activities more or less in the subjective day. Whatever the species, the locomotor patterns became in majority multimodal for treated individuals. We noted, in addition, the absence of the unimodal profile. Through periodogram analysis, ultradian and circadian components were determined whatever the experimental conditions. The most important rhythmicity was determined in the control individual of A. officinalis (73.7%) as well as of C. elongata (52.6%). Furthermore, the locomotor behavior is less stable for contaminated individuals of the two sympatric species. Moreover, contrary to C. elongata, A. officinalis individuals became significantly more active after their exposure to zinc contaminated litter (alpha(DD+Zn) = 5h03 +/- 2h33).

Freshly collected individuals of Hemilepistus reaumurii from the marginal zone of a salt lake in Bchachma (Middle of Tunisia) were seasonally housed in a controlled environment cabinet. The aim of this study was to investigate the effect of sex on the locomotor activity rhythm of this species. Locomotor activity rhythm of males and females of this species was recorded during each season under light-dark cycle (nLD) at a constant temperature of 18 +/- 0.5 degrees C. Results showed that both males and females of H. reaumurii exhibited a day activity in late winter and in spring and a crepuscular activity during the other seasons. Results showed also that the locomotor rhythms of males and females were controlled by an endogenous component with circadian period. Furthermore, locomotor rhythm was more stable and better defined in males than in females during spring under constant darkness. The most important locomotor activity time (alpha) was recorded in winter and spring whatever the sex. However, our finding demonstrated that males were more active than females in late winter. On the other hand, females were more active than males during spring. The variation of activity patterns according to the sexes and seasons is discussed.

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.

The locomotor activity of the supralittoral Oniscidea species, Tylos europaeus collected from Barkoukech Beach was monitored in individual animals under natural light/dark cycle, constant darkness and continuous light. Actograms and mean activity curves showed that this species concentrated its activity during the experimental and subjective night whatever the regimen. This nocturnal rhythm was controlled by ultradian and circadian components mostly close to 12 h and 24 h with the nLD cycle and lengthened under aperiodic regimens. Globally, the number of active animals, the stability of the rhythm and the mean activity time were lowest under continuous light suggesting that this regimen could be as a stress condition for the locomotor behaviour of Tylos europaeus.

The ultrastructural changes on the hepatopancreas of Porcellio laevis individuals were investigated after their exposure to a mixture of cadmium (Cd) and zinc (Zn) during four weeks. At the end of the experiment, trace element (TE) concentrations were determined using atomic absorption spectrometry (AAS). The growth of individuals was calculated and compared among the treatments. From the first week until the end of the experiment, a weight gain was observed in P. laevis individuals. Additionally, the TE concentrations in the hepatopancreas and in the rest of the body were considerable and seem to be dose dependent. Moreover, our results confirmed the role of the hepatopancreas as the main storage organ. Thus, the conducted transmission electron microscopy highlighted remarkable alterations on the hepatopancreas cells resulting from the Cd and Zn bioaccumulation. The displayed alterations are principally the disorganization of the S- and B-cells leading to a destruction of the microvilli border, an increase of the lipid droplets and mitochondria as well as the appearance of trace elements in the form of B-type granules. Based on the obtained results herein, we can conclude that Porcellio laevis might be a good candidate in the prevention of TE pollution in the terrestrial ecosystems.

ABSTRACT Behavioral responses to trace metals (TM) in Armadillidium granulatum Brandt, 1833 collected from Sebkha El Ouafi were studied under controlled laboratory conditions. Avoidance test was conducted in individuals exposed to cadmium (Cd), lead (Pb) and zinc (Zn) during 48 hours. The locomotor activity was studied under entraining conditions (LD) and constant darkness (DD) in the control animals as well as those exposed to contaminated soil. Whatever the tested metal, the animals did not show avoidance behavior. The determined efficient concentration (EC50) was equal to 3.4 mg/L for Cd, 451 mg/L for Pb and 1043 mg/L for Zn. Furthermore, results revealed the existence of nocturnal behavior whatever the experimental conditions. Periodogram analysis showed the existence of ultradian and circadian periods. This last was globally longer for contaminated specimens than the control ones under entraining conditions as well as under constant darkness. Exposed animals to cadmium showed the most important activity time under DD (αDD = 8h01 ± 3h27) contrary to that observed under nLD cycle (αLD = 3h43 ± 2h36). In addition, control specimens and those exposed to Cd and Pb were characterized by a phase delay contrary to those exposed to Zn which showed a phase advance.

The hepatopancreas of crustacean species has been recognized as an important target organ for studying the toxic effects of trace metals (TM). This dynamic organ, with its capability of detoxifying trace metals, often indicates distinct pathological disturbances. This study dealt with the evaluation of the histological alterations in the hepatopancreas of the supralittoral amphipod Orchestia montagui Audouin, 1826 exposed to a mixture of copper and zinc. After exposure, the hepatopancreas was dissected and its ultrastructure was observed using transmission electron microscopy. The obtained results showed that the body mass differed from the control organisms depending on the nominal metal concentration to which they were exposed. The hepatopancreas of unexposed and exposed animals were compared for the detection of histological changes. Significant dose-dependent alterations were noted in all the treatment groups. Among these histological changes of the hepatopancreas in O. montagui, we noted the loss of cell structure, especially cell remoteness and border lyses, a reduction in the nuclear volume, an increase in cytoplasm density with trace metals in both nucleus and vacuoles, a disorganization and destruction of microvilli and a condensation of the majority of cell organelles, and mitochondria swelling. Through this study, O. montagui could be a good indicator providing measurable responses. It could be an attractive candidate for the biochemical study of TM toxicity in coastal ecosystems.

The structure and dynamics of the natural population of Hemilepistus reaumurii, a terrestrial desert isopod, were studied. Results showed a well-balanced overall sex-ratio revealing a stable population. It was a seasonal reproduction with one breeding period, occurring in spring. Overall, analysis of the size frequency showed the presence of three cohorts during the 18 months of monitoring. Lifespan was estimated at 14 months. H. reaumurii appeared as an annual species, with semelparous females that exhibited a univoltine life cycle. Furthermore, results showed, for the first time in this specie, that males have larger body lengths and masses than females. This may suggest strongly the development of a sexual body length and mass dimorphism in this species. (c) 2021 Elsevier GmbH. All rights reserved.

To estimate trace element bioaccumulation in Armadillo officinalis, specimens were collected then exposed to contaminated sediments with copper and zinc for three weeks.At the beginning of the experiment, the individuals were weighted and their masses were monitored every 7 days during 3 weeks. At the end of the experiment, the body metal concentrations were measured using flame atomic emission spectrometry. A mass gain was highlighted after trace elements exposure. The bioaccumulation factor results showed that the species could be considered as a macroconcentrator of copper (BAF > 2) and a deconcentrator of zinc (BAF < 2).Microscopy observations of hepatopancreas cells showed morphological and histological changes even at the lowest concentration. Through these results, the isopod A. officinalis could be used as relevant monitor organisms for soil metal contamination.

In this present paper, we propose to characterize the locomotor behavior of the Oniscidea Armadillidium granulatum Brandt, 1833 and to highlight the effect of age on its locomotor patterns. Individuals of A. granulatum were collected from the supralittoral zone of Sebkha El Ouafi. Adult and young specimens were maintained in spring under two successive regimens: the light-dark (LD) cycle and the constant darkness (DD) at a constant temperature. Whatever the age, double-plotted actograms and waveforms showed that specimens of A. granulatum concentrated their activity during the experimental and subjective nights. In addition, the majority of locomotor activity patterns were unimodal; whereas, adults and juveniles intensified their activities respectively around the dusk and in the middle of the night. Through periodogram analysis, circadian and ultradian components were determined. The first one was significantly longer under DD than under natural LD cycle for adults as well as for juveniles. These last were characterized by the most stable and well-defined locomotor activity rhythm. Furthermore, Adult specimens were more active under entraining conditions contrary to juveniles that showed an important activity time under DD. With reference to environmental stability and variability, the differences of locomotor activity characteristics observed between juveniles and adults were explained as a need for plasticity to adapt to environmental changes.

The seasonal variation of the locomotor activity rhythm of Talitrus saltator was investigated in a population from the supra-littoral zone of the new harbour beach of Ghar El Melh. The rhythm was recorded in individual animals over the four seasons under two simultaneous experimental regimens: the natural light/dark cycle and the continuous darkness. Results revealed that, whatever the season, actograms and mean activity curves showed globally that individuals of T. saltator concentrated their activity during the experimental and subjective day. In addition, specimens exhibited a nocturnal circadian rhythm of locomotor activity with an ultradian component. Under light-dark cycle, circadian periods determined by periodogram analysis in four seasons were appreciably similar and were close to 24 h. Under constant darkness, the circadian period was longer in the autumn (tau(DD) = 1501MODIFIER LETTER PRIME.81 +/- 56MODIFIER LETTER PRIME.2) than the other seasons. In addition, the study of the mean activity times calculated for four seasons showed that the most important activity of individuals was observed in the spring and the autumn under entraining and free-running conditions, respectively.