Northern Tunisia Research Articles

Adsorption and mineralization of metalaxyl-m and chlorpyrifos in irrigated Mediterranean soil under the effects of salinity.

To evaluate the effects of salinity on the fate of pesticides in a Mediterranean irrigated system, experiments were carried out under laboratory conditions to determine the adsorption, desorption, and mineralization of chlorpyrifos (CPF) and metalaxyl-M (MET) in a soil sample from an irrigated field in northern Tunisia. Adsorption/desorption isotherms and mineralization kinetics data were obtained over a realistic range of salinities via batch equilibrium and incubation techniques. On the basis of the experimental results, MET has a lower sorption capacity than CPF does, and the adsorption data for both compounds were better fitted by the Freundlich equation, with Kf values of 0.477, 0.486, 0.426, 0.444 and 0.474 L kg-1 for MET and 38.994, 39.084, 40.644, 44.055 and 45.185 L kg-1 for CPF at salinities of 0, 1, 2, 5 and 10 g L-1, respectively. According to the mineralization experiments, increasing salinity increased the half-lives of both pesticides. For MET, the DT50 values in unsterilized soil were 206.68, 220.74, 222.16, and 238.73 days, and those in sterilized soil were 2772.58, 4077.33, 6301.33, and 8664.33 days at salinities of 0, 1, 2, 5, and 10 g L⁻1, respectively. For CPF, the DT50 values were 115.52, 138.62, 157.53, and 177.73 days in unsterilized soil and 346.57, 533.19, 693.14, and 990.21 days in sterilized soil. In terms of leaching behavior, the calculated groundwater ubiquity score (GUS) values for the MET and CPF indicate that the MET is classified as a leacher and that the CPF is classified as a nonleacher.

Seismic reflection interpretation and structural characterization of a strategic deep aquifer reservoir in a semi-arid region: a case study of the Oued Gueniche plain, Northern Tunisia

Seismic reflection interpretation and structural characterization of a strategic deep aquifer reservoir in a semi-arid region: a case study of the Oued Gueniche plain, Northern Tunisia

Monitoring Coastal Evolution and Geomorphological Processes Using Time-Series Remote Sensing and Geospatial Analysis: Application Between Cape Serrat and Kef Abbed, Northern Tunisia

The monitoring of coastal evolution (coastline and associated geomorphological features) caused by episodic and persistent processes associated with climatic and anthropic activities is required for coastal management decisions. The availability of open access, remotely sensed data with increasing spatial, temporal, and spectral resolutions, is promising in this context. The coastline of Northern Tunisia is currently showing geomorphic process, such as increasing erosion associated with lateral sedimentation. This study aims to investigate the potential of time-series optical data, namely Landsat (from 1985–2019) and Google Earth® satellite imagery (from 2007 to 2023), to analyze shoreline changes and morphosedimentary and geomorphological processes between Cape Serrat and Kef Abbed, Northern Tunisia. The Digital Shoreline Analysis System (DSAS) was used to quantify the multitemporal rates of shoreline using two metrics: the net shoreline movement (NSM) and the end-point rate (EPR). Erosion was observed around the tombolo and near river mouths, exacerbated by the presence of surrounding dams, where the NSM is up to −8.31 m/year. Despite a total NSM of −15 m, seasonal dynamics revealed a maximum erosion in winter (71% negative NSM) and accretion in spring (57% positive NSM). The effects of currents, winds, and dams on dune dynamics were studied using historical images of Google Earth®. In the period from 1994 to 2023, the area is marked by dune face retreat and removal in more than 40% of the site, showing the increasing erosion. At finer spatial resolution and according to the synergy of field observations and photointerpretation, four key geomorphic processes shaping the coastline were identified: wave/tide action, wind transport, pedogenesis, and deposition. Given the frequent changes in coastal areas, this method facilitates the maintenance and updating of coastline databases, which are essential for analyzing the impacts of the sea level rise in the southern Mediterranean region. Furthermore, the developed approach could be implemented with a range of forecast scenarios to simulate the impacts of a higher future sea-level enhanced climate change.

Assessing shell morphology in freshwater mussels (Mollusca: Bivalvia: Unionidae) from the Maâden River, Tunisia: Insights from geometric morphometrics and shape descriptors

Identifying freshwater mussel species within the Unionidae family can be challenging due to systematic confusion. This study investigates shell shapes to identify four sympatric species of freshwater mussels (Potamida littoralis, Unio durieui, U. gibbus, and U. ravoisieri) in the Maâden river (northern Tunisia) using two morphological approaches: global shape descriptors and geometric morphometrics of shell contours. The results revealed significant differences in global shape descriptors among the species. More in-depth analyses showed distinct shape variations, with P. littoralis and U. gibbus significantly differing from U. durieui and U. ravoisieri across most descriptors. Notably, U. durieui and U. ravoisieri exhibited similar shape traits, differing primarily in roundness, characterized by low circularity and high ellipticity. Principal Component Analyses depicted substantial morphological variance, with Procrustes data requiring the first two components to fully elucidate dispersion. Linear Discriminant Analysis revealed effective discrimination among species, with an accuracy rate of over 74 % in classifying individuals into their respective populations across both approaches. Geospatial analyses indicated varying influences of latitude, longitude, and altitude on shell morphology among species. Latitude had noteworthy impacts on P. littoralis, approaching significance for shape descriptors and Procrustes data. Conversely, U. durieui and U. gibbus displayed minimal geographic influence on shell morphology, while U. ravoisieri showed significant variations across these parameters. This study highlights the distinct morphological differences among sympatric mussel species in northern Tunisia, providing valuable insights for conservation efforts, especially for species vulnerable to climate change.

Multi-criteria site selection for wastewater treatment plant in Bent Saidane, Tunisia

Optimal site selection for the establishment of a municipal waste-water-treatment plant (WWTP) is an amazingly complex task that involves several factors such as regulations, as well as environmental, economic and social considerations. This paper presents the criteria and applied methods (geographic information system (GIS)/fuzzy analytical hierarchy process (AHP)) used in the screening of potential sites for the WWTP of the Bent Saidane rural locality (northern Tunisia). For this reason, nine factors accompanied by three sets of site selection criteria were used. GIS-based multi-criteria analysis techniques based on the standardised fuzzy logic concept and weighted overlay were applied for generation of all maps in the Universal Transverse Mercator coordinate system. Multiscale evaluations based on the weighted linear combination method were also assessed. The study indicated that 0.14 and 0.11% of the total area of the Bent Saidane locality were found to be highly suitable and very highly suitable, respectively. According to these results, the GIS followed by the fuzzy AHP method could pinpoint the optimal sites selected as the most suitable, due to their minimum impact on the environment, as well as on public health, for the construction of a future WWTP in the Bent Saidane rural area.

Climate change impacts on the hydrological behaviour of watershed in northeastern Tunisia (Oued El Abid watershed)

Climate change significantly impacts watershed hydrology, altering water supplies, natural disasters, and eco-hydrologic processes. These effects vary geographically, with some regions facing severe droughts while others experience increased precipitation and flooding. Climate change influences atmospheric evaporation demand, precipitation patterns, vegetation composition, streamflow characteristics, and groundwater dynamics. The temperature increases and rainfall changes in some watersheds can lead to increased potential evapotranspiration and decreased streamflow and soil water. Flood frequency analyses indicate an overall increasing trend in the latter half of the 21st century. The Oued El Abid catchment area, as like all catchments in northern Tunisia, is likely to be subject to major climatic and hydrological variations as a result of climate change. Advanced hydrological modelling using the HBV-Light model was set up to simulate current conditions and future scenarios based on Afric-Cordex climate models. The model demonstrates robust performance, achieving Nash-Sutcliffe Efficiency (NSE) values of 0.71 in calibration (1972-1992), and 0.66 in validation from 1993-2001. This climate change has a direct effect on the hydrological projections, which reveal significant changes, with annual flow reductions ranging from 35% to 43%, with more severe impacts under the RCP8.5 scenario for 2069-2099. Spring and summer seasons are particularly vulnerable, showing flow decreases of up to 68% and over 40%, respectively, extreme monthly variability is projected, reaching 88% reduction in July under RCP8.5. This research provides important results for water resource managers, highlighting the necessity of long-term planning and sustainable water management practices in the face of climate change.

Geometric Characterization of the Mateur Plain in Northern Tunisia Using Vertical Electrical Sounding and Remote Sensing Techniques

The Mateur aquifer system in Northern Tunisia was examined using data from 19 water boreholes, 69 vertical electrical sounding (VES) stations, and a Sentinel-2 satellite image. Available boreholes and their corresponding logs were compared to define precisely the multi-layer aquifer system, including the Quaternary and Campanian aquifers of the Mateur plain. Quantitative interpretation and qualitative evaluation of VES data were conducted to define the geometry of these reservoirs. These interpretations were enhanced by remote sensing imagery processing, which enabled the identification of the Mateur plain’s superficial lineaments. Based on well log information, the lithological columns show that the Quaternary series in the Ras El Ain region contains a layer of clayey, pebbly, and gravelly limestone. Additionally, in the Oued El Tine area, a clayey lithological unit has been identified as a multi-layer aquifer. The study area, exhibiting apparent resistivity values ranging between 20 and 170 Ohm·m, appears to be rich in groundwater resources. The correlation between the lithological columns and the interpreted VES data, presented as geoelectrical cross-sections, revealed variations in depth (8–106 m), thickness (10 to 55 m), and resistivity (20–98 Ohm·m) of a coarse unit corresponding to the Mateur aquifer. Twenty-three superficial lineaments were extracted from the Sentinel-2 image. Their common superposition indicated that both of them are in a good coincidence; these could be the result of normal faults, creating an aquifer system divided into raised and sunken blocks.

The Role of Organic Matter and Hydrocarbons in the Genesis of the Pb-Zn-Fe (Ba-Sr) Ore Deposits in the Diapirs Zone, Northern Tunisia

The Role of Organic Matter and Hydrocarbons in the Genesis of the Pb-Zn-Fe (Ba-Sr) Ore Deposits in the Diapirs Zone, Northern Tunisia

Miocene magmatism in Northern Tunisia and its geodynamic implications

The Nefza igneous rocks in Northern Tunisia belong to the Miocene magmatic belt extending from Northern Tunisia to Morocco and consist mainly of Serravallian–Tortonian granodiorite and rhyodacite (~ 14–8 Ma) and Messinian basalts (~ 8–6 Ma). Differences in geochemical composition between units have been interpreted to be the result of geodynamic processes in the upper mantle below the Western Mediterranean area, but their implications for Northern Tunisia are unclear due to limited data. In this contribution, we present an updated geodynamic model for Northern Tunisia based on new petrographic and whole-rock geochemical results from the Nefza magmatic suite from outcrop and OB45 drill core samples. Petrographic observations show that rhyodacites display a microlithic texture with quartz, plagioclase, K-feldspar, biotite, and glass, whilst granodiorite contains plagioclase, quartz and exhibits fine-grained texture with a 2–3 mm crystal size. The Nefza magmatic rocks are overprinted by multiple weathering and alteration processes with loss of ignition (LOI) ranging between 0.88 and more than 5 wt%. The linear relationships between mobile elements (Ca, Na, P, K, Mg, Si), large-ion lithophile elements (LILE), and LOI suggest element mobilisation during alteration. Major and trace element compositions show the Nefza magmatic rocks plot in the rhyolite, dacite, and trachydacite fields for felsic rocks and plot in the basalt and trachybasalt fields for mafic rocks. Granodiorite and rhyodacite rocks exhibit negative Eu anomalies and a LILE enrichment (Rb, Ba, Pb) relative to high-field-strength elements (HFSE: Nb, Ta, Hf, Zr, REE). Mafic rocks enriched in LILE show geochemical characteristics between calc-alkaline and alkaline trends. Comparison with nearby regions suggests that the generation of calc-alkaline magmas resulted from the partial melting of the lithospheric mantle due to slab break-off or tearing in Eastern Algeria. The upward flow of asthenospheric material through the widening tear in the sinking slab leads to partial melting of the mantle and shallowing of the lithosphere–asthenosphere boundary, ultimately leading to the formation of alkaline magma. The Nefza geochemical variations underscore Mediterranean upper mantle heterogeneity, offering crucial insights into Mediterranean geodynamics. More studies are needed to constrain mantle dynamics and the region’s complex geological history.

First Evidence of Rickettsia conorii Infection in Dogs in Northern Tunisia.

A cross-sectional study was carried out, between April 2021 and June 2022, to understand the role of dogs in the circulation of rickettsiosis in Tunisia. The presence of specific IgG antibodies against Rickettsia conorii was analyzed by indirect immunofluorescence test. By qPCR, blood and ticks were collected from 136 dogs examined at the Canine Department of National School for Veterinary Medicine of Tunisia. These dogs were also analyzed to detect Rickettsia DNA. The rate of Rickettsia seropositivity in 136 dogs was 55.14%. A total of 51 (53%) seropositive dogs showed clinical and biological signs such as fever and anorexia as well as thrombocytopenia and anemia. By qPCR, targeting the mitochondrial 16S rRNA gene, no Rickettsia DNA was detected in the blood. On the other hand, qPCR followed by sequencing revealed the presence of R. conorii subsp. raoultii in 7 tick pools of the 51 pools composed of the 227 ticks collected. A One Health approach to raise the awareness of dog owners to control tick infestations is imperative, given the dangers of canine zoonoses.

First Molecular and Phylogenetic Identification of Toxoplasma Gondii in Sheep Liver Intended for Human Consumption in Northern Tunisia.

The aim of this study was to estimate the molecular infection prevalence of Toxoplasma gondii in sheep liver tissues destined for human consumption. A total number of 224 liver tissues were collected from slaughtered sheep in Sejnane slaughterhouse (Northwest Tunisia). PCR was used to detect T. gondii DNA in liver tissues followed by phylogenetic analysis of amplicons. The phylogenetic tree was then constructed to compare the partial sequences of the ITS1 gene with GenBank sequences.The overall molecular prevalence of T. gondii in sheep livers was 25% (56/224). The highest molecular prevalence of T. gondii was recorded in sheep aged of less than one year old (27.3%; 52/190). Infection prevalence was significantly higher in Noire de Thibar breed (33%; 17/51) compared to other breeds (p = 0.023). There were no differences depicted according to sheep's gender. The T. gondii sequences obtained in the present study (GenBank accession numbers: OR509829 and OR509830) were 98.40-100% homologous to T. gondii sequences published in the GenBank. These results highlight a high level of T. gondii contamination of tissues destined for human consumption. Further studies are needed to improve our knowledge on different genotypes of T. gondii that infect Tunisian sheep population.

Morphological responses of ostracods to heavy metal contamination: freshwater ostracods as bioindicators of pollution in Ichkeul Lake and rivers ecosystem, northern Tunisia

Morphological responses of ostracods to heavy metal contamination: freshwater ostracods as bioindicators of pollution in Ichkeul Lake and rivers ecosystem, northern Tunisia

Genome and pan-genome analysis of a new exopolysaccharide-producing bacterium Pyschrobacillus sp. isolated from iron ores deposit and insights into iron uptake.

Bacterial exopolysaccharides (EPS) have emerged as one of the key players in the field of heavy metal-contaminated environmental bioremediation. This study aimed to characterize and evaluate the metal biosorption potential of EPS produced by a novel Psychrobacillus strain, NEAU-3TGS, isolated from an iron ore deposit at Tamra iron mine, northern Tunisia. Genomic and pan-genomic analysis of NEAU-3TGS bacterium with nine validated published Psychrobacillus species was also performed. The results showed that the NEAU-3TGS genome (4.48 Mb) had a mean GC content of 36%, 4,243 coding sequences and 14 RNA genes. Phylogenomic analysis and calculation of nucleotide identity (ANI) values (less than 95% for new species with all strains) confirmed that NEAU-3TGS represents a potential new species. Pangenomic analysis revealed that Psychrobacillus genomic diversity represents an "open" pangenome model with 33,091 homologous genes, including 65 core, 3,738 shell, and 29,288 cloud genes. Structural EPS characterization by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy showed uronic acid and α-1,4-glycosidic bonds as dominant components of the EPS. X-ray diffraction (XRD) analysis revealed the presence of chitin, chitosan, and calcite CaCO3 and confirmed the amorphous nature of the EPS. Heavy metal bioabsorption assessment showed that iron and lead were more adsorbed than copper and cadmium. Notably, the optimum activity was observed at 37°C, pH=7 and after 3 h contact of EPS with each metal. Genomic insights on iron acquisition and metabolism in Psychrobacillus sp. NEAU-3TGS suggested that no genes involved in siderophore biosynthesis were found, and only the gene cluster FeuABCD and trilactone hydrolase genes involved in the uptake of siderophores, iron transporter and exporter are present. Molecular modelling and docking of FeuA (protein peptidoglycan siderophore-binding protein) and siderophores ferrienterobactine [Fe+3 (ENT)]-3 and ferribacillibactine [Fe+3 (BB)]-3 ligand revealed that [Fe+3 (ENT)]-3 binds to Phe122, Lys127, Ile100, Gln314, Arg215, Arg217, and Gln252. Almost the same for [Fe+3 (ENT)]-3 in addition to Cys222 and Tyr229, but not Ile100.To the best of our knowledge, this is the first report on the characterization of EPS and the adsorption of heavy metals by Psychrobacillus species. The heavy metal removal capabilities may be advantageous for using these organisms in metal remediation.

Pesticide contamination pattern of surface water in an urban–agricultural mediterranean watershed (Wadi Guenniche, Bizerte Lagoon, Northern Tunisia)

Two years of monthly sampling and hydrological monitoring were performed at the outlet of a Mediterranean watershed in northern Tunisia to determine the contents of 469 pesticide active ingredients and metabolites in water and evaluate their behavior. Wadi Guenniche is a tributary of the Bizerte coastal lagoon, with a watershed area of 86 km2, which exhibits pluvial cereal, legume, and orchid cultivation and irrigated market gardening. Twenty-nine pesticide active ingredients and 2 metabolites were detected in water. Twenty-four pesticide active ingredients were authorized for use in Tunisia. Among them, 14 had never been mentioned in previous farmer surveys. Five herbicides and their metabolites were the most frequently detected: aminomethylphosphonic acid (AMPA) (100%), glyphosate (94%), simazine (94%), 2,4-D (70%), and deisopropylatrazine (DIA) (47%). The detection frequency and concentration range suggested that the phytosanitary pressure and resulting water contamination are close to those on the northern Mediterranean shore. These results, in addition to characterizing the pollution state, emphasized the need for additional studies on the use and fate of pesticides on the southern shore of the Mediterranean Sea, particularly in Tunisia.

Morphometric analysis of Muraena helena and Conger conger in the coastal waters of northern Tunisia

This study examined morphometric characteristics of 237 M. helena and 123 C. conger individuals collected from three sites located in the north coast of Tunisia (Bizerte, Ghar el melh and Haouaria). In M. helena, males seems larger than females; total length ranged from 494 to 1050 mm and from 490 to 976 mm, for males and females, respectively. Also the morphometric segregation is different between males and females according to the capture site. Morphological analysis showed that for males, the population of Ghar el melh presents a morphometric divergence. However, for females the population of Haouaria presents the higher values. The length of C. conger ranged from 490 to 1110 mm. Individuals of Ghar el melh and Haouaria presented similar morphometric characteristics, these two populations being morphologically different from Bizerte population.

Knowledge, attitudes and practices of sheep owners regarding abortion in Northern Tunisia.

Abortion in ewes causes high economic losses and represents a threat for human health due to abortive zoonotic pathogens. The present study aimed to assess the knowledge, attitudes and practices (KAP) among sheep owners in the northern Tunisia regarding ewes' abortions. Between February 2021 and May 2022, a structured questionnaire containing both close and open-ended questions was applied to 120 sheep owners in northern Tunisia. The data collected were analysed by chi-square test using Epi info 6 software. The majority (75%) of participants reported a history of abortion in their sheep flocks. Sheep owners thought that the most frequent cause of abortion was physical factors, such as trauma, climate and stress (60%±5.5%; 48/80), followed by toxicity (15%±4%; 12/80), metabolic and nutritional conditions (12.5%±3.7%; 10/80), vaccination (5%±2.4%; 4/80) and infectious causes (7.5%±2.9%; 6/80) (p<0.001). The majority of animal owners reported that abortions occurred mainly during autumn (39.6%±5%; 38/96), followed by summer (27%±4.5%; 26/96), winter (23%±4.3%; 22/96) and spring (10.4%±3.1%; 10/96) (p<0.001). Approximately, half (45.8%±5%; 55/120) of interviewed farmers would not take any action if an abortion occurred. Half of the interviewed farmers (50.5%±5.1%; 48/95) did not apply any preventive measures when manipulating aborted ewes, and most of the sheep owners (77.3%±3.8%; 92/119) did not know that aborted ewes could transmit zoonotic pathogens. Our survey concluded that sheep owners in Northern Tunisia had poor knowledge and attitudes as well as applied limited actions concerning several health aspects related to abortion. Education programmes should be established in order to improve Tunisian sheep owners' KAP regarding abortion.

Formation mechanism and structural evolution of recumbent fold nappes: New insights from the bizerte area, northern Tunisia

The structural analysis of the Bizerte area in northern Tunisia, utilizing well data and field observations, reveals a complex arrangement of fold structures characterized by recumbent fold nappes to local sheath-like fold structures, indicative of a deep detachment phenomenon. The genesis and present geometry of these fold structures unravel a multifaceted structural history: (i) In the Tortonian folding phase, a detachment mechanism may have initiated the formation of a horizontal shearing plane at the base of the Paleocene marls. The gradual evolution of syn-shear recumbent fold nappes into sheath folds within sedimentary to pseudo-metamorphic rocks is attributed to a flow perturbation process analogue to “layer-parallel shearing,” dictating the geometric configuration of folds subsequent to a simple shear inducing perturbations in pre-existing layer disturbances. (ii) During the Late Quaternary shortening phase, a NW-trending right lateral shear zone emerged, delineated by the reactivation of pre-existing faults under compression. The reorientation of the anterior fold axes is attributed to the counterclockwise rotation of rigid blocks within the framework of P-type conjugate fractures. (iii) The transition to thin-skinned tectonics, characterized by the uplift of previously buried material, was characterized by a significant increase in shortening during Neogene events, encompassed in the broader regional geodynamic context of continental collision. From the Lower Quaternary onward, the structural model exhibits a combination of layer-parallel and layer-normal shear processes.

Delineating the evolutionary pathway to multidrug-resistant outbreaks of a Mycobacterium tuberculosis L4.1.2.1/Haarlem sublineage

ObjectivesWe sought to capture the evolutionary itinerary of the Mycobacterium tuberculosis L4.1.2.1/Haarlem sublineage in northern Tunisia, where it caused a major multidrug-resistant (MDR) tuberculosis outbreak in a context strictly negative for HIV infection. MethodsWe combined whole genome sequencing and Bayesian approaches using a representative collection of drug-susceptible and drug-resistant L4.1.2.1/Haarlem clinical strains (n = 121) recovered from the outbreak region over 16 years. ResultsIn the absence of drug resistance, the L4.1.2.1/Haarlem sublineage showed a propensity for rapid transmission as witnessed by the high clustering (44.6%) and recent transmission rates (25%), as well as the reduced mean distance between genome pairs. The entire pool of L4.1.2.1/Haarlem MDR strains was found to be linked to either the aforementioned major outbreak (68 individuals, 2001-2016) or to a minor, newly uncovered outbreak (six cases, 2001-2011). Strikingly, the two outbreaks descended independently from a common ancestor that can be dated back to 1886. ConclusionsOur data point to the intrinsic propensity for rapid transmission of the M. tuberculosis L4.1.2.1/Haarlem sublineage in northern Tunisia, linking the overall MDR tuberculosis epidemic to a single ancestor. These findings bring out the important role of the bacillus’ genetic background in the emergence of successful MDR M. tuberculosis clones.

Comparison of Actual Evapotranspiration assessment by satellite-based model SEBS and hydrological model BBH in northern Tunisia

Comparison of Actual Evapotranspiration assessment by satellite-based model SEBS and hydrological model BBH in northern Tunisia

Water scarcity conflicts in a community managed irrigation system in Northern Tunisia: Supporting dialogue and negotiation

Water scarcity conflicts in a community managed irrigation system in Northern Tunisia: Supporting dialogue and negotiation