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Water resources management within water-stressed coastal aquifers, specifically in the arid and semi-arid Mediterranean basin, engenders significant challenges. Their distinctive attributes, characterized by their proximity to the sea and their complex hydrogeological characteristics, contribute to the difficulties faced in their management. Factors such as high coastal population density, fast urbanization and industrialization, agricultural and touristic expansion, intensify the demand for freshwater, compounded by extensive groundwater extraction. Consequently, the relentless depletion of aquifers deeply affects the intrusion of salt water and the quality of groundwater resources. The Plio-Quaternary aquifer system in Eastern Tunisia, Mediterranean region, has experienced significant groundwater salinization since the 1970s. Field surveys and chemical analysis were conducted to measure different parameters such as groundwater static level, electrical conductivity, major elements, and nitrates. Accordingly, to understand the salinization processes, delineate salt groundwater plumes, and identify vulnerable areas, a geoelectrical approach was employed. These approaches were valuable in detecting salinized areas within the aquifers and comprehend the mechanisms of groundwater salinization. High salinity levels and interactions between groundwater and surface water were identified along the coast and near Sebkha Moknine. The hydrodynamic behavior of saltwater, whether it ascends or descends, directly impacts the hydrodynamic systems of the Mahkia Ksour Essaf aquifer and the overall groundwater quality. These investigations show valuable results to perform for a better management and prevention from pollution and overuse of water resources of the studied region. [ABSTRACT FROM AUTHOR]

Abstract In the Great Sebkha Basin of Oran, water flows, both surface and subterranean, originate on the slopes and converge toward the discharging area of the salt Lake Great Sebkha of Oran (≈ 80 m above sea level). Isotopic water tracing of 2H, 18O, 14C, and 13C was carried out on the main aquifer formations to clarify the phenomena of evaporation, dissolution, mixing of different water bodies, and their residence time in the aquifer system. The data concern: the salt Lake of the Great Sebkha of Oran, the Quaternary alluvial water table of the periphery, the limestone Miocene, the Brédéah pumping station (whose waters are polluted by brackish water intrusions), deepwater tabler table of the Mio-Pliocene complex of the Plain of Maflak, the Pliocene of the Plain of Tameira, and the Thermal Complex of Hammam Bou Hadjar. The d18O levels range from −9.61 to + 4.8 ‰ V-SMOW at the salt Lake of Great Sebkha of Oran. The 2H contents range from −70 to 20. Minimum values characterize run off from the northern slopes of the Tessala. The 13C contents of dissolved total inorganic carbon (TDI) measured ranged from −10.92 to −3.9 ‰ vs PDB. The activities of the 14C are divided between 2 and 51 PMC. The highest activity in 14C (≈50 PMC) is measured on samples taken from the Miocene limestones of Djebel Murdjadjo.

The sedimentological and geochemical properties of a 146 cm long sediment core collected from Sebkha el Melah (Ml core) in south‐eastern Tunisia have been used to infer the genesis and evolution of the Sebkha el Melah over the last 5000 years. Two main sedimentary units have been defined: a huntite [Mg3Ca(CO3)4] unit at the bottom of core Ml is covered by a second unit made up of siliciclastic and evaporitic materials. The huntite level is synchronous with Holocene marine transgression, which was followed by a regression of about 5300 years bp. Geochemical data (major and trace element), magnetic analyses, grain‐size distribution and microtexture of quartz grains were performed to assess the sediment provenance. The upper unit of Ml core is characterized by alternations between fluvial, aeolian and evaporite deposits. Redox proxies displaying marked Fe/Ca and Rb/S peaks, in addition to high magnetic susceptibility (MS) values, polymodal grain‐size frequency curves, as well as sub‐angular grains with V‐shaped percussion cracks, are suggestive of palaeohydrological events. In contrast, a decreasing trend in the low MS values, bi‐modal grain‐size frequency curves as well as well‐rounded quartz grains with crescent percussion marks would indicate enhanced aeolian sand input in the sebkah el Melah sequence. Moreover, geochemical proxies suggest formation of evaporite facies under a strongly warm climate contemporary with marine intrusion. [ABSTRACT FROM AUTHOR]

Detrital quartz grains extracted from sebkha sediments in southeastern Tunisia underwent scanning electron microscopy analysis to identify sediment sources and assess the influence of the saline environment on the grains. Core sediments collected from Sebkha el Melah and Sebkha Mhabeul cover the last 5000 and 2000 BP, respectively. The uppermost Unit III, present in both cores, exhibits two distinct facies based on the mechanical microtextures of its quartz grains. The aeolian facies sediments are characterized by quartz grains with rounded outlines, upturned plates, and crescentic percussion marks. In contrast, the fluvial facies sediments are associated with quartz grains featuring subangular outlines, v-shaped percussion cracks, conchoidal fractures. Observations on the quartz grains of the sebkhas suggest multiple transportation and processing events, indicating long-distance transport and rapid deposition rates. The majority of quartz grains appear to originate from the surrounding terrain, reflecting the dynamic geological history of the region. This study delves into the connection between microtexture variations on quartz grain surfaces and specific historical climatic conditions in the sebkhas. By examining geochemical variations along the cores, facies with elevated salt concentrations corresponding to warmer periods reveal extensively weathered quartz grains. This substantial chemical alteration is evident through microtextures such as oriented etch pits, anastomosed dissolution networks and solution crevasses. The profound dissolution has significantly impacted the quartz lattice, resulting in the decomposition of the grains and the formation of "cauliflower" or "spongy" shapes, erasing prior microtextures. Conversely, during less warm periods, quartz dissolution was less severe, thereby preserving microtextures. Sand grain surfaces are notably sensitive to both transport processes and variations in the physicochemical environment. In the hypersaline and confined environments of sebkhas in southeastern Tunisia, potent post-sedimentary processes can obliterate and obscure the original microtextures recorded on grains from previous environments due to highly fluctuating physicochemical conditions. • Quartz grain microtextures have been analyzed to identify sediment sources in Tunisian sebkhas. • Fluvial deposits show angular grains with v-shaped cracks, indicating water transport. • Aeolian deposits show rounded grains with crescentic percussion marks, indicating wind transport. • High salt concentrations recorded during warm periods enhance chemical weathering on quartz grains. • Hypersaline conditions can obscure previous textures on quartz grain surfaces. [ABSTRACT FROM AUTHOR]

In the Great Sebkha Basin of Oran, water flows, both surface and subterranean, originate on the slopes and converge toward the discharging area of the salt Lake Great Sebkha of Oran (≈ 80 m above sea level). Isotopic water tracing of 2H, 18O, 14C, and 13C was carried out on the main aquifer formations to clarify the phenomena of evaporation, dissolution, mixing of different water bodies, and their residence time in the aquifer system. The data concern: the salt Lake of the Great Sebkha of Oran, the Quaternary alluvial water table of the periphery, the limestone Miocene, the Brédéah pumping station (whose waters are polluted by brackish water intrusions), deepwater tabler table of the Mio-Pliocene complex of the Plain of Maflak, the Pliocene of the Plain of Tameira, and the Thermal Complex of Hammam Bou Hadjar. The d18O levels range from −9.61 to + 4.8 ‰ V-SMOW at the salt Lake of Great Sebkha of Oran. The 2H contents range from −70 to 20. Minimum values characterize run off from the northern slopes of the Tessala. The 13C contents of dissolved total inorganic carbon (TDI) measured ranged from −10.92 to −3.9 ‰ vs PDB. The activities of the 14C are divided between 2 and 51 PMC. The highest activity in 14C (≈50 PMC) is measured on samples taken from the Miocene limestones of Djebel Murdjadjo. [ABSTRACT FROM AUTHOR]

The sedimentological features of the Holocene deposits outcropping along southeastern Tunisia show a littoral para-sequence including red silt, conglomerates, bioclastic, and siliciclastic deposits. At Sebkha Boujmel, they are represented by a buried lagoon characterized by a transgressive–regressive para-sequence. The latter displays seven facies integrated within a transgressive biodedritic complex followed by bioclastic and oolitic sands, laminated silty carbonate sand, and eolian silts rich in gypsum, crowned by microbial mats. Lateral correlations have identified the spatiotemporal distribution of facies. The neighboring Sebkha el Melah (10 km further north) displays a Holocene para-sequence consisting of a transgressive biodetritic complex overtopped by thick evaporitic series. The sedimentation in this region, which has remained tectonically stable since the last 125 ka BP, was driven by coastal thresholds, climate and recent sea level changes that formed three different para-sequences in three nearby sites. Our observations with those available from previous studies provide new insights on the evolution on the landscape of southeastern Tunisia before and during the Holocene that driven the formation of an inland shoaled homoclinal ramp with a lagoon system. [ABSTRACT FROM AUTHOR]

The Sebkha of Oran, given its large size, is considered to be a remarkable feature of the west Algeria. The study of its evolution proved to be essential, following many interrogations specifically concerning its extension and its role in the ecological balance of the region. We aim to study the changes of the Sebkha over the last 20 years. To conduct the study, we used the Synthetic Aperture Radar (SAR) imagery, which offers spatial and temporal, regular, and precise tracking of surfaces. The diachronic analysis, based on amplitude images captured between 1992 and 2011, demonstrated the possibility of mapping the sebkha at different dates in order to apprehend its evolution over this period. The results obtained reveal a southwesterly extension caused by the phenomenon of saline crystallization gradually and steadily gaining ground, which corresponds to the inclination of the basin and the main wind direction of the region.

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. [ABSTRACT FROM AUTHOR]

The Great Sebkha of Oran is a closed depression located in northwestern of Algeria. Despite the ranking of this sebkha among the wetlands of global importance by Ramsar Convention in 2002, no studies on the fungal community in this area have been carried out. In our study, samples were collected from two different regions. The first region is characterized by halophilic vegetation and cereal crops and the second by a total absence of vegetation. The isolated strains were identified morphologically then by molecular analysis. The biotechnological interest of the strains was evaluated by testing their ability to grow at different concentration of NaCl and to produce extracellular enzymes (i.e., lipase, amylase, protease, and cellulase) on solid medium. The results showed that the soil of sebkha is alkaline, with the exception of the soil of cereal crops that is neutral, and extremely saline. In this work, the species Gymnoascus halophilus, Trichoderma gamsii, the two phytopathogenic fungi, Fusarium brachygibbosum and Penicillium allii, and the teleomorphic form of P. longicatenatum observed for the first time in this species, were isolated for the first time in Algeria. The halotolerance test revealed that the majority of the isolated are halotolerant. Wallemia sp. and two strains of G. halophilus are the only obligate halophilic strains. All strains are capable to secrete at least one of the four tested enzymes. The most interesting species presenting the highest enzymatic index were Aspergillus sp. strain A4, Chaetomium sp. strain H1, P. vinaceum, G. halophilus, Wallemia sp. and Ustilago cynodontis.

Salt deposits and upwellings in oasis environments have several adverse effects on space and agricultural production. Land subsidence may occur as a result of the gradual dissolution of the saline formations in the basement; date palms, the main wealth of oases, are affected by the rise of salt in the soils, hence loss of yield, degradation, and death. Sebkhas, vast water accumulation depressions, are a visual indicator of surface salinization. In this article, the evolution of the Oum Rneb sebkha near Ouargla is presented. Satellite images from 1987, 2000, and 2005 were used. The 2005 image allowed the development of a chain of treatments based on conventional treatments (analysis of main components, classifications, channel combinations) and based on a semi-empirical model. A field campaign in November 2013 enabled the validation of the treatments and interpretation of these results. [ABSTRACT FROM AUTHOR]

In our research work, the central focus is upon the multi-proxy analysis of sediment core recovered in sebkha Mhabeul (southeastern Tunisia), provides the first high-resolution, continuous sedimentary record in the region, extending back to mid Holocene. The integration of sedimentary facies, elemental geochemistry and magnetic susceptibility, together with an age model based on tephrochronology, enable reconstruction of the main hydrological and climate changes in the region. Arid conditions, represented by thick gypsum interval at the bottom of Mh2 core occurred during Bronze Age. However, the period extending from Iron Age to the Present time is characterized by alternating episodes of higher effective moisture and severely arid climatic conditions. Magnetic and geochemical compositions provide information concerning changes of elemental and mineralogical compositions from flood events materials interrupted by thin deposits of aeolian origin. Indeed, six binary data consist of dominant silty fractions rich in heavy minerals and increasing with wadi-derived elements like Na 2 O/K 2 O and Na 2 O/Fe 2 O 3. These wadi sediments are covered with sandy/silty Saharan aeolian input occurring commonly after rapid and short climate change towards drier conditions. These sandstorm events are known for increasing redox-sensitive elements Na 2 O/K 2 O. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The Sebkha of Oran, given its large size, is considered to be a remarkable feature of the west Algeria. The study of its evolution proved to be essential, following many interrogations specifically concerning its extension and its role in the ecological balance of the region. We aim to study the changes of the Sebkha over the last 20 years. To conduct the study, we used the Synthetic Aperture Radar (SAR) imagery, which offers spatial and temporal, regular, and precise tracking of surfaces. The diachronic analysis, based on amplitude images captured between 1992 and 2011, demonstrated the possibility of mapping the sebkha at different dates in order to apprehend its evolution over this period. The results obtained reveal a southwesterly extension caused by the phenomenon of saline crystallization gradually and steadily gaining ground, which corresponds to the inclination of the basin and the main wind direction of the region. [ABSTRACT FROM AUTHOR]

The study area is located in the municipality of El-Mahmel located in the extension East and North east of the Aurès Nemamcha mountains in the city of Khenchela, Northern east of Algeria. This study is related to a research on groundwater pollution from anthropogenic emissions and secondly by the migration of salt water intrusion from the Sebkha in response to intensive pumping. The physico-chemical characterization of water by measurements on site and laboratory analysis allowed defining the degree of saltwater contamination and its spatial spread. This salt contamination of groundwater would be accentuated by the discharge of wastewater into the Sebkha, the irrational use of chemical fertilizers, pesticides and intensive pumping. By this action, we alerted the government to the need to build a wastewater treatment plant, the need for a delineation of protection areas or would be prohibited to establish drilling. Finally, make farmers of El Mahmel aware of the risk of deterioration in the water quality monitoring of disease outbreaks and soil infertility by the accumulation of salts (alkalization and sodization of soil) with the disappearance of all cultures if they not reduce pumping water.

The main purpose of this research is to study the microbial diversity of actinobacteria, living in “Ezzemoul” and “Djendli” sebkhas soils. These salt lakes are situated in the east of Algeria and they are microbiologically underexploited. Such unexplored ecological niches have been considered by many authors as sources of novel actinobacteria and bioactive molecules. Actinobacteria play an important role in safeguarding the environment by improving plant growth through nitrogen fixation, biodegradation, and bioremediation. Therefore, studying the diversity and distribution of actinobacteria in such special environments is important for determining the ecological and biotechnological roles of these microorganisms. In this article, we focused on the occurrence and the diversity of actinobacteria from sebkhas using two techniques: cultural and culture-independent (molecular cloning). The latter are based on phylogenetic analysis of the 16S rDNA gene. Thus, the cultural method allowed us to obtain 62 isolates: 40 from the “Ezzemoul” site and 22 from the “Djendli” site. These isolates tolerate mainly 2, 5, and 10% sodium chloride (NaCl) and belong to the genera Nocardiopsis, Streptomyces, and Rhodococcus. Moreover, the molecular cloning gave us 39 clones. Twenty-four clone sequences from “Ezzemoul” site are affiliated to the genera Demequina, Plantactinospora, Friedmanniella, and Mycobacterium. Also, 15 clone sequences from “Djendli” site are related to the genera Marmoricola, Phytoactinopolyspora, Streptomyces, and to an unclassified actinobacterial clone. Some sequences from both sites are related to uncultured clones. In addition to the data provided by the cultural method, molecular cloning allowed us to have additional information about the unknown actinobacteria, uncultured ones as well as on the genera that exist in both sites. So, the cultural method is complementary to the culture-independent one, and their combination revealed an important diversity in targeted saline environments. Furthermore, all new isolated strains that tolerate 10% NaCl may have a very interesting biotechnological potential in the future.

Four sediment cores, drilled at Younga and Ouadrane Sebkhas (Hachichina wetland), were selected for micropalaeontological, sedimentological, geochronological and geochemical investigation coupled to hierarchical cluster and correspondence analysis. Our research aimed at reconstructing the past biodiversity, the Holocene palaeoenvironmental evolution and the responsible forcing. Subsurface sediments record four major phases: i) the first one is characterized by poorly to very poorly sorted silts, the dominance of the lagoonal/estuarine ostracod and the lagoonal/marine foraminifera and high values of terrestrial geochemical element ratios, such as K/Al and Fe/Al, which indicate an estuarine lagoon; ii) two major marine transgressions, TR1 and TR2, allowing the settlement of widely opened lagoons towards 7160-8680 and 5070-5520 cal yr BP, are marked by the enhancement of the marine/brackish ostracods and marine foraminifera, the improvement of species number, individuals number and H and E index values and of the marine element ratios such as Cl/Al and Sr/Al; iii) the opening of the lagoon is hampered by the action of drift currents allowing the genesis of sand spit and the settlement of a closed lagoon, towards 2610-3610 cal yr BP, characterized by the enhancement of lagoonal/estuarine ostracods and lagoonal/marine foraminifera and the increase of the individuals number; iv) the dominance of the lagoonal/estuarine ostracods and the lagoonal/marine foraminifera and the decline of the species number and density mark a brackish lagoon, also characterized by very poorly sorted silts transported by uniform suspension, which evolves to the actual sebkha. This evolution, within a global climate alteration context, from an estuarine environment to the present sebkha passing by an opened lagoon, is linked to the complex hydrographic setting of the sebkhas and of the Ouadrane Wadi outlet discharging in the Hachichina wetland.

Control of K+ and Na+ transport plays a central role in plant adaptation to salinity. In the halophyte Hordeum maritimum , we have characterized a transporter gene, named HmHKT2;1 , whose homolog HvHKT2;1 in cultivated barley, Hordeum vulgare , was known to give rise to increased salt tolerance when overexpressed. The encoded protein is strictly identical in two H. maritimum ecotypes, from two biotopes (Tunisian sebkhas) affected by different levels of salinity. These two ecotypes were found to display distinctive responses to salt stress in terms of biomass production, Na+ contents, K+ contents and K+ absorption efficiency. Electrophysiological analysis of HmHKT2;1 in Xenopus oocytes revealed distinctive properties when compared with HvHKT2;1 and other transporters from the same group, especially a much higher affinity for both Na+ and K+, and an Na+–K+ symporter behavior in a very broad range of Na+ and K+ concentrations, due to reduced K+ blockage of the transport pathway. Domain swapping experiments identified the region including the fifth transmembrane segment and the adjacent extracellular loop as playing a major role in the determination of the affinity for Na+ and the level of K+ blockage in these HKT2;1 transporters. The analysis (quantitative reverse transcription-PCR; qRT-PCR) of HmHKT2;1 expression in the two ecotypes submitted to saline conditions revealed that the levels of HmHKT2;1 transcripts were maintained constant in the most salt-tolerant ecotype whereas they decreased in the less tolerant one. Both the unique functional properties of HmHKT2;1 and the regulation of the expression of the encoding gene could contribute to H. maritimum adaptation to salinity. [ABSTRACT FROM AUTHOR]

The Great Sebkha of Oran is a closed depression located in northwestern of Algeria. Despite the ranking of this sebkha among the wetlands of global importance by Ramsar Convention in 2002, no studies on the fungal community in this area have been carried out. In our study, samples were collected from two different regions. The first region is characterized by halophilic vegetation and cereal crops and the second by a total absence of vegetation. The isolated strains were identified morphologically then by molecular analysis. The biotechnological interest of the strains was evaluated by testing their ability to grow at different concentration of NaCl and to produce extracellular enzymes (i.e., lipase, amylase, protease, and cellulase) on solid medium. The results showed that the soil of sebkha is alkaline, with the exception of the soil of cereal crops that is neutral, and extremely saline. In this work, the species Gymnoascus halophilus, Trichoderma gamsii, the two phytopathogenic fungi, Fusarium brachygibbosum and Penicillium allii, and the teleomorphic form of P. longicatenatum observed for the first time in this species, were isolated for the first time in Algeria. The halotolerance test revealed that the majority of the isolated are halotolerant. Wallemia sp. and two strains of G. halophilus are the only obligate halophilic strains. All strains are capable to secrete at least one of the four tested enzymes. The most interesting species presenting the highest enzymatic index were Aspergillus sp. strain A4, Chaetomium sp. strain H1, P. vinaceum, G. halophilus, Wallemia sp. and Ustilago cynodontis. [ABSTRACT FROM AUTHOR]

Imlili Sebkha is a stable and flat depression in southern Morocco that is more than 10 km long and almost 3 km wide. This region is mainly sandy, but its northern part holds permanent water pockets that contain fauna and flora despite their hypersaline water. Google Earth Engine (GEE) has revolutionized land monitoring analysis by allowing the use of satellite imagery and other datasets via cloud computing technology and server-side JavaScript programming. This work highlights the potential application of GEE in processing large amounts of satellite Earth Observation (EO) Big Data for the free, long-term, and wide spatio-temporal wet/dry permanent salt water cavities and moisture monitoring of Imlili Sebkha. Optical and radar images were used to understand the functions of Imlili Sebkha in discovering underground hydrological networks. The main objective of this work was to investigate and evaluate the complementarity of optical Landsat, Sentinel-2 data, and Sentinel-1 radar data in such a desert environment. Results show that radar images are not only well suited in studying desertic areas but also in mapping the water cavities in desert wetland zones. The sensitivity of these images to the variations in the slope of the topographic surface facilitated the geological and geomorphological analyses of desert zones and helped reveal the hydrological functions of Imlili Sebkha in discovering buried underground networks.

The highlands of Eastern Algeria are characterized by an endorheism namely a local base level that does not allow the water system to get to the sea. The Area of chotts and sabkhas of Gadain region can be considered as an area of degradation lands due to the dynamics of sabkhas and chotts that are localized and installed on large areas on one hand and accelerated anthropogenic pressure on the other hand. This dynamic often presents special large extension, this study requires accurate and geo localized information's. The analysis of the dynamics of chotts and sabkhas based on medium resolution satellite images on two different dates (Landsat TM 1987 and TM 2009) specializes (mapping) and evaluates this dynamic. The comparison of the results provides an overview of the affected areas by the dynamics of sabkhas and chotts and their direction for 22 years.

Objective: To study the antimicrobial activity of actinomycetes isolated from sabkha of Kenadsa and identification of the isolate interesting. Methods: Eighteen strains were isolated, using four culture media from sebkha of Kenadsa (Bechar, Southwestern Algeria). Screening of antimicrobial activity consisted of two steps: in primary screening, antibacterial activity was determined by using the agar plug method against test strains; in secondary screening, better isolate which showed a good activity in the first screening was selected to extract antimicrobial substances. The antimicrobial activities of extracts were evaluated by using Kirby–Bauer disc diffusion method. Partial characterization of antimicrobial products was performed on the basis of chemical revelations, UV–vis spectrometry and infrared spectroscopy. The identification of isolate interesting was performed through morphological, chemical, biochemical and physiological characteristics. Results: All isolates showed antimicrobial activity against at least one microorganism test. One isolate, LAM143cG3, was selected for its broad spectrum and high antimicrobial activity. The isolate LAM143cG3 was identified as Spirillospora sp. The comparison between the species of this genus (Spirillospora rubra and Spirillospora albida) and our isolate indicated the existence of several physiological and biochemical differences which led us to suppose that this was a new member of this genus. Primary characterization of antimicrobial substances produced by the isolate LAM143cG3 indicated the presence of amines and phenols. The UV–vis spectrum suggested a non-polyenic nature of substances secreted by our isolate, while infrared confirmed the presence of amine groups. Conclusions: The result of the present study revealed that sebkha of Kenadsa was rich in rare actinomycetes, that secreted interesting antimicrobial substance.

Quaternary formations occupy all the lower levels of large sedimentary basins, forming thus ephemeral lakes in closed salt depressions, called commonly "sebkhas." They are continental aquatic ecosystems, classified as wetlands of inland backwaters. They provide several functions; such as aquatic life, geochemical and hydrological cycles. The aim of this paper is to characterize the surface states of salty soils of sebkha Sefioune and its surroundings in the north of Ouargla (South-eastern Algeria), by linking the remote sensing data acquired by satellite, observation and exploration of land surface in order to differentiate the surface states of the study area (sebkha Sefioune and nearby). The realization of spectral signatures from the satellite image (Landsat 7 ETM +), allowed us to individualize the soil surface states of sebkha Sefioune and its surroundings (North of Ouargla-Algeria) according to the spectral responses of each surface states. This approach allows us to say that the land surface states have different spectral behaviour according to their colour, water content (humidity), structure (roughness,) mineralogical and geochemical nature. [ABSTRACT FROM AUTHOR]

Supervised and unsupervised satellite image classifications have progressed greatly in recent years. However, discrimination difficulties still remain among classes that directly affecting data extraction and surface mapping accuracy. The Ouargla region in southeastern Algeria is intersected by wadis, where direct communication between the shallow groundwater table and these dry, overlying ephemeral stream beds exists. Underflowing groundwater exfiltrates into low-lying aeolian blowouts or endorheic basins forming oases, chotts, and sebkhas, commonly known as saline wetlands. These wetlands are becoming increasingly vulnerable to anthropogenic stress, resulting in significant water degradation. Wetland microclimates are very important to arid regions, as they promote oasis ecosystem sustainability and preservation. High water salinity in these ecosystems, however, directly affects flourishing habitat and undermines successful desert oasis development. The objective of this work is to choose the best classification method to identify saline wetlands by comparison between the different results of land use mapping within the Ouargla basin. Landsat ETM+ (2000) satellite imagery, using visual analysis with colored compositions, has identified various forms of saline wetlands in the Ouargla region desert environment in southeast Algeria. The results show that supervised classification is validated in the identification of Saharan saline wetlands, and that support vector machine (SVM) algorithm presents the best overall accuracy. [ABSTRACT FROM AUTHOR]

Integrated sedimentological studies, diagenesis, sequential analysis and clay mineralogy on the Upper Paleocene rocks in Tamerza area provide important information on the reconstruction of the depositional basin, cyclicity, and paleoclimatic contexts. Facies analysis and petrographic studies have led to the recognition of nine facies that were deposited in three facies belts: Sebkha, inner ramp and outer ramp summarized in a carbonate ramp model: Homoclinal ramp under an arid climate. The upward and lateral changes in thickness and composition show a general regressive trend that records a transition from an outer ramp to Sebkha, creating different types of confinement. The facies stacking patterns constitute several kinds of meter-scale, shallowing-upward cycles. Nine different types of depositional cycles and several models of Sebkha sequences were defined. These different types of facies, characterized within the Thelja Formation, compose seven depositional sequences, mainly made of carbonates, marls and evaporates. Detailed multi approach analysis provides important information on evaporitic sequence stratigraphy. In carbonates beds, the diagenetic analysis provides an overview and chronology of diagenetic processes. A particular attention was paid to early stage cementation which enables us to characterize better the depositional environments. In addition to cementation, other features define the diagenetic history. X-ray diffraction reveals the presence of smectite suggesting an arid climate. Moreover, the clinoptilolite and the frequency of primary dolomite indicate different degrees of confinement. The seven depositional sequences showing a hierarchical organization of many cycles, as described above, suggested that eustatic sea level oscillations caused by cyclic perturbations of the Earth's orbit play a fundamental role in determining the formation of hierarchical cyclic rhythmicity. [ABSTRACT FROM AUTHOR]

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Copyright of Bulletin de la Société de Pathologie Exotique is the property of John Libbey Eurotext Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective To study the antimicrobial activity of actinomycetes isolated from sabkha of Kenadsa and identification of the isolate interesting. Methods Eighteen strains were isolated, using four culture media from sebkha of Kenadsa (Bechar, Southwestern Algeria). Screening of antimicrobial activity consisted of two steps: in primary screening, antibacterial activity was determined by using the agar plug method against test strains; in secondary screening, better isolate which showed a good activity in the first screening was selected to extract antimicrobial substances. The antimicrobial activities of extracts were evaluated by using Kirby–Bauer disc diffusion method. Partial characterization of antimicrobial products was performed on the basis of chemical revelations, UV–vis spectrometry and infrared spectroscopy. The identification of isolate interesting was performed through morphological, chemical, biochemical and physiological characteristics. Results All isolates showed antimicrobial activity against at least one microorganism test. One isolate, LAM143cG3, was selected for its broad spectrum and high antimicrobial activity. The isolate LAM143cG3 was identified as Spirillospora sp. The comparison between the species of this genus ( Spirillospora rubra and Spirillospora albida ) and our isolate indicated the existence of several physiological and biochemical differences which led us to suppose that this was a new member of this genus. Primary characterization of antimicrobial substances produced by the isolate LAM143cG3 indicated the presence of amines and phenols. The UV–vis spectrum suggested a non-polyenic nature of substances secreted by our isolate, while infrared confirmed the presence of amine groups. Conclusions The result of the present study revealed that sebkha of Kenadsa was rich in rare actinomycetes, that secreted interesting antimicrobial substance. [ABSTRACT FROM AUTHOR]

Studies revealed the role of Artemia salina as intermediate host in the life-cycle of a cestode species parasitizing flamingos, i.e. Flamingolepis liguloides. Cysticercoids of this parasite were found for the first time in the Algerian populations of Artemia salina in winter of 2000 and 2001 in Chott Marouane and spring of 2003 in Sebkha Ez-Zemoul. The prevalence ranged between 10 and 33% for the two examined Artemia populations. The intensity of infection was 1–3 cysticercoids per individual. The abdomen was the most targeted site of infection (95% of the population of Sebkha Ez-Zemoul) followed by the thorax and the ovisac. Infected females were less fertile than uninfected ones (24.83 vs 43.70 cysts/brood) in Sebkha Ez-Zemoul or castrated in Chott Marouane. [ABSTRACT FROM AUTHOR]

Abstract: Relations between climate change and landscape evolution during the last two millennia in southeastern coastal Tunisia have been documented using high-resolution reconstruction of flood history and fire activity in the Sebkha Mhabeul core. The age model, based on tephrochronology, indicates that the core extends from Roman to modern times and encompasses the well-defined climatic periods of the last two millennia. This record provides a first palaeoecological/palaeoclimatic high resolution reconstruction in North Africa using a cross-disciplinary approach with both physical (grey-scale intensity, quartz particles) and biological (charcoal and pollen) indicators. The flood history shows four wet/dry cycles (ca. AD 550–950, 950–1300, 1300–1570 and 1570–1870) of different duration. Major hydrological instabilities are concentrated during the Medieval Climate Anomalies and the early Little Ice Age, between AD 1000 and 1550. Direct correlation between climate and fire cannot be established suggesting that the fire history of the Sebkha environment is mainly influenced by human activity. This study demonstrates the great value of sebkhas as palaeoenvironmental archives. [Copyright &y& Elsevier]