Island Of Djerba Research Articles

Assessment of surface sediment dynamics and response of benthic macrofauna assemblages in Boughrara Lagoon (SW Mediterranean Sea)

A study was conducted in the spring of 2009, the winters of 2010 and 2013, and in the summer of 2012 at 13 stations in Boughrara Lagoon, Tunisia (southern Mediterranean). The country⿿s largest lagoon, it is considered to be an anthropogenically stressed area, though a major tourist centre⿿Djerba Island⿿is located along its northern shores. The lagoon bottoms were studied via analyses of grain size, surface sediment composition, total organic matter (TOM) and through the trophic and functional organisation of benthic macrofauna. The results indicate that the bottoms are composed of fine, medium or coarse sands and that sediment distribution is controlled by water movement. Estimation of TOM content revealed that the studied samples present both normal and imbalanced sediments. The structure and organisation of the lagoon⿿s benthic macrofauna are dominated by select deposit feeders and underwent significant changes during the period 2010⿿2013.Subjected for decades to increased pollution due to growing human activities in the surrounding area, Boughrara Lagoon now appears to be impacted by certain environmental/anthropogenic stressors, as indicated by the presence of pollution-tolerant bio-indicator species in the imbalanced area. The response of the lagoon ecosystem to changes in benthic sediment deposition provides a potential assessment tool for similar habitats elsewhere.

The Importance of the Image of a Destination in the Choice and Intention of Revisiting: The Case of Island of Djerba.

The image of a destination is a key element to attract tourists. This image is based on the perceptions of individuals about the destination, which determines their touristic behavior and, consequently, their choice of destination (Woodside and Lysonski 1989; Echtner and Ritchie, 1993). Thus, the objective of this research is to analyze the strategic dimension of the image of a destination as a strategic management tool in order to understand the conductive elements to maintain and / or revive touristic streams to the destination. For this goal, authors have conducted a study including an analysis of the image of the island of Djerba with Jewish tourists. The results will be discussed later on strategic options of what could a positive image represent in order to conceive a successful attraction strategy which arouses the intention of revisiting within tourists.

Lagocephalus sceleratus (Gmelin, 1789) expands through the African coasts towards the Western Mediterranean Sea: A call for awareness

The silver-cheeked toadfish Lagocephalus sceleratus is one of the most recent invaders in the Mediterranean Sea and a serious risk for public health. In June 2011, an awareness campaign to disseminate information related with this toxic species was launched by the Tunisian Ministry of Agriculture. Whilst providing a step toward the development of an appropriate early warning system, this case highlights a remarkable geographical extension of L. sceleratus along the entire Tunisian shoreline (from the island of Djerba to the region of Tabarka). We illustrate how the first step in the process of effectively managing the risks posed by an invasive species is to engage and communicate with the public.

Surface sediment dynamics along the eastern coast of Djerba Island (Gabes Gulf, Tunisia)

Surface sediment dynamics were studied on the eastern coast of Djerba Island (Gabes Gulf, southern Tunisia) by simultaneously assessing currents, as well as the mineralogy and grain size of bottom sediments. Harmonic analysis of time-series sea data at Ras Taguermess and El Kantara illustrated the dominance of a semi-diurnal tidal component, with a period of 12h42min. Orthogonal Empirical Functions analysis of tidal currents along the major axis at El Kantara produced a standard deviation of +45cms−1 with a main angle of 29°, whereas at Ras Taguermess it was 5cms−1 with a north-south direction. Analysis of grain sizes from sediment samples taken between Ras Taguermess and Ras Marmour show that the shallow bottoms (0–10m) are composed of fine, medium and coarse sands. Mean grain size ranges between 100 and 763μm, a distribution attributed to a high level of wave activity. Moreover, two mean grain size gradients were evidenced: the first is alongshore from north to south, from Ras Taguermess to Aghir, and the second from south-east to north-west, between Ras Marmour and Bin El Ouediane. Quartz is abundant from Ras Taguermess to Sidi Garous along the many beaches, while it quantitatively decreased in the eroded area between Sidi Garous and Aghir. Thus, transport is from north to south. A high build-up of sediment was observed in Bin El Ouediane, resulting from a barrier island formation.

Monitoring shoreline change on Djerba Island using GIS and multi-temporal satellite data

In the absence of a generic approach to study shoreline changes, this research focus on the development of a generic methodology to detect, measure, analyze, and predict shoreline changes to manage coastal environment. The unique strength of this approach is that it incorporates image processing techniques, remotely sensed derived data into a GIS to analyze measure, and predict and visualize shoreline changes. It is independent from the study region or the remote sensing data. This methodology uses Speeded Up Robust Feature to detect the study regions from satellite images automatically. Also, it proposes a model of shoreline using the Canny edge detector on Normalized Difference Water Index image. To measure the changes, Digital Shoreline Analysis System extension of ArcGIS was used and the End Point Rate (EPR) and Linear Regression Rate (LRR) approaches were used on the modeled shoreline. The EPR is calculated by dividing the distance of shoreline movement by the time elapsed between the oldest and the most recent shoreline. A LRR statistic can be determined by fitting a least-squares regression line to all shoreline points for a particular transect. Three regions of the island of Djerba in Tunisia were selected for this study; Rass Errmall, El Kastil, and Aghir. Accretions as well as erosion processes were observed in the study areas between 1984 and 2009. The average of the erosion was around −6.95 m/year in Aghir. The average of erosion is around −4.09 m/year and accretion trend is around +11.7 m/year in Rass Errmall. El Kastil was under a remarkable accretion with 21.14 m/year during the same period.

Celiac disease in Tunisian children: A second screening study using a “new generation” rapid test

This work aims to estimate celiac disease prevalence in school-children in the island of Djerba and assess rapid method feasibility for screening. We screened 2064 schoolchildren by a rapid method to detect IgA anti-tissue transglutaminase and IgA deficiency. Children with positive results were tested for IgA anti-transglutaminase and anti-endomysium by conventional tests. In positive children, intestinal biopsy was performed. IgA deficiency suspected by rapid method was confirmed by nephelometry. In these cases IgG anti-endomysium was performed. Rapid test was positive in 7 children; conventional serology was positive in all and 6 of them accepted the biopsy. Total villous atrophy was observed in 5 while intestinal mucosa was normal in one. Among children with positive serology, 3 had silent form, 1 chronic diarrhea, one growth failure and 2 had borderline growth. IgA deficiency was suspected in 13 cases and was confirmed in 11 children tested. Prevalence of celiac disease was 0.24–0.34% and that of IgA deficiency 0.5–0.6%. This screening study confirms that celiac disease is relatively common in schoolchildren in Tunisia. It confirms also that even those with symptoms typical for celiac disease escape diagnosis. Rapid test is better accepted by parents and children than test requiring a venous blood sample.

Automatic Measurement of Shoreline Change on Djerba Island of Tunisia

This study presents measurement of changes using image processing techniques, Digital Shoreline Analysis System (DSAS) and Landsat images along the coast of the island of Djerba, Tunisia. Three regions of this island were selected: Rass Errmall, El Kastil and Aghir. Accretions as well as erosion processes were observed in the study areas between 1984 and 2009. The average of the erosion was around -6.95 m/yr in Aghir. The average of erosion is around -4.09 m/yr and accretion trend is around +11.7 m/yr in Rass Errmall. El kestil was under a remarkable accretion with 21.14 m/yr during the same period.

The relation between the RO fouling membrane and the feed water quality and the pretreatment in Djerba Island plant

The reverse osmosis system is exposed to many problems that affect its efficiency. The major problem is fouling membrane which is frequently related to the interaction between the quality of feed water and the pretreatment process. This paper treats two problems of RO plant in Djerba Island, the sulfuric water and the fouling membrane. For the first problem, the anaerobic process showed better performance than the aerobic process. Furthermore, the aerobic process of non-sulfuric water was affected after 6 years of operation with a fouling phenomenon at R.O membrane. This problem was correlated with the increase of the operating pressure, pressure drop and permeates conductivity. To identify causes of these problems, different investigations are carried out. Membrane autopsy, chemical analyses of feed water and follow-up of the operation parameters are performed. The membrane autopsy was achieved by SEM/EDS. The results show that the film is composed mostly with organic matter, silica, metallic matter and aluminum phosphate. This result is correlated with the phosphonate based antiscalant composition. Therefore, antiscalant selection and dosage appear to be critical for membrane fouling development.

A Carnian (Julian) microflora from the Djerba Melita 1 Borehole (Gulf of Gabes, South-Eastern Tunisia)

This study represents a contribution to the biostratigraphic characterization of the Gulf of Gabes Triassic series. Diverse andwell preserved palynological assemblages from the Djerba Melita 1 (DJM1)well in the Djerba Island (Gulf ofGabes, Southern Tunisia) are here presented and discussed. A Carnian microflora is recorded in the Triassic portion of the drilled succession. The co-occurrence of Ladinian-lower Carnian taxa in association with typical Carnian elements allows to refer the microflora to the lower part of the Duplicisporites continuus palynological assemblage (late Julian, Austrotrachyceras austriacus Subzone). A semi-quantitative analysis of the assemblages also seems to document the occurrence, in the middle-upper part (units 3 and 4) of DJM1 well of the Aulisporites-Aratrisporites Acme Zone, an ammonoid-calibrated palynological event occurring in several European successions, referring to the late Julian/early Tuvalian. The occurrence of this acme zone in Southern Tunisia encourages its application also to Triassic sedimentary records belonging to the southern Tethyan margin.

Polymorphism Study of the Insulin Receptor Substrate IRS1 and IRS2 Genes Associated with Type 2 Diabetes in Ethnic Groups of Djerba Island

Aim: We aimed to evaluate the influence of the Gly972 Arg and Ala513Pro variants of the insulin receptor substrate1 gene (IRS1) and the Gly1057 Asp variant in IRS on type 2 diabetes mellitus (T2DM) in Arab and Berber men and women from Djerba Island, Tunisia. Methods: Genotypes, allelic and genotypic frequencies were studied. The amplified products were analyzed by Restriction Fragment Length Polymorphism (RFLP) methods by comparing T2DM with healthy controls from the same ethnicity. Results: No differences in genotype or allelic frequencies were found between T2DM and healthy controls in either Arab or Berber ethnic groups. Conclusion: The Gly972 Arg and Ala513Pro variants in IRS1 and Gly1057 Asp in IRS2 polymorphisms are not associated with T2DM in the Arab or Berber populations of Djerba Island

Chemical and Biological Characteristics of Essential Oil of Rosmarinus officinalis Cultivated in Djerba

The essential oils extracted by Clavenger apparatus from leaves of Rosmarinus officinalis cultivated in different areas in Djerba (Island in the southern of Tunisia) were evaluated for their chemical composition (GC and GC-MS methods), antioxidant (DPPH method) and antibacterial activities (agar-well diffusion method). GC-MS analysis revealed the presence of three chemotypes of oils: 1,8-cineole, 1,8-cineole/camphor/α-pinene/camphene and 1,8-cineole/camphor/α-pinene/ verbenone/borneol which was not previously detected in Tunisian Rosmarinus officinalis. The three chemtypes exhibited moderate antioxidant activity with an IC50 ranged from 4.186 mg/ml for chemotype I to 7.298 for chemotype II and showed strong to moderate antibacterial activity against the six bacterial strains tested with a MIC ranged from 0.156 to 1.25 mg/mL (Chemotype I and chemotype II) and from 1.25 to 5 mg/mL (chemotype III). This study showed that the essential oil extracted from Rosmarinus officinalis cultivated in Djerba has similar chemical composition and biological activities as essential oil isolated from wild growing Rosmarinus officinalis.

Ecrobia grimmi in brackish Lake Sawa, Iraq: indirect evidence for long-distance dispersal of hydrobiid gastropods (Caenogastropoda: Rissooidea) by birds

Ecrobia grimmi in brackish Lake Sawa, Iraq: indirect evidence for long-distance dispersal of hydrobiid gastropods (Caenogastropoda: Rissooidea) by birds

Influence of socioeconomic lifestyle factors and genetic polymorphism on type 2 diabetes occurrences among Tunisian Arab and Berber groups of Djerba Island

Type 2 diabetes mellitus (T2DM) is characterized by three major metabolic abnormalities: impaired insulin-stimulated glucose uptake in muscle and adipose tissues, alterations in glucose-stimulated insulin secretion, and increased hepatic glucose production. Both genetic and environmental factors contribute to its development. The insulin gene (INS), insulin receptor gene (INSR), and insulin receptor substrate 1 gene (IRS1), identified by polymerase chain reaction and digestion with selected restriction enzymes PstI, NsiI, and BstnI, have been proposed as T2DM candidate genes. To determine the contribution of genetic and environmental factors on the occurrence of T2DM, we examined the frequency of T2DM among two ethnically diverse populations, Arabs and Berbers, who have shared the same environment, the island of Djerba, for thousands of years. Both populations have a high prevalence of obesity,T2DM, and a high consanguinity rate. A total of 162 T2DM men and women were matched to 110 healthy male and female controls. Results showed that the NsiI polymorphism in INSR and BstnI polymorphism of IRS1 were significantly associated with T2DM only among the Berber group. The PstI polymorphism in INS, was not associated with T2DM in either group. Sedentary lifestyles, lower physical activity, and lower educational levels were associated with T2DM among the Berber group. These findings suggest that the insulin receptor gene and lifestyle factors in combination may contribute to the occurrence of T2DM in the Berber portion of this island population.

Occurrence of the alien nudibranch Melibe viridis (Kelaart, 1858) (Opisthobranchia, Tethydidae), in the Maltese Islands

The alien dendronotacean nudibranch Melibe viridis (Kelaart, 1858), a tropical Indo-Pacific species that seems to have been introduced by shipping into the Mediterranean via the Suez Canal, and which has established populations in Greece, Turkey, Cyprus, Montenegro, Croatia, NW Sicily, southern peninsular Italy and Djerba Island in the Gulf of Gabes, is recorded for the first time from Malta. A thriving population was observed on a soft sediment bottom at a depth of 18-20 m off the western coast of the island of Comino (Maltese Islands). It is suggested that this species was introduced into Malta due to a natural range expansion of surrounding populations.

The G1057D polymorphism of IRS-2 gene is not associated with type 2 diabetes and obese patients among ethnic groups in Tunisian population

Background Type 2 of diabetes is the most common metabolic disorder and results from the interaction between genetic and environmental factors. Insulin receptor substrate-2 (IRS-2), one of the major substrates of the insulin receptor, has a crucial role in insulin signalling and in beta cell development and survival. While several polymorphisms have been identified in the IRS-2 gene, the association of the Gly1057Asp polymorphism with type 2 diabetes has been studied in European and Chinese populations, but the results have been inconsistent. Objectives The aim of this study was to investigate the association of Gly1057Asp polymorphism in insulin receptor substrate-2 (IRS-2) gene among patients with type 2 diabetes in well defined ethnic groups from Djerba Island in Southeastern Tunisia. Methods The studied population (172 Arabs and 100 Berbers) includes 162 patients with type 2 diabetes and 110 healthy controls. BMI was calculated for each subject. The subjects were unrelated and randomly selected Arabs and Berbers were equally distributed between controls and diabetics. The G1057D polymorphism of the IRS-2 gene was genotyped using PCR-RFLP assay. Results This case/control study indicated that frequency of the IRS-2 Gly1057Asp polymorphism was not significantly different between the healthy controls and type 2 diabetic groups, neither between healthy nor obese subjects, in both ethnic groups. Moreover, this polymorphism is present at a lower frequency in Djerbian than in neighbouring European populations. Conclusion These results strongly argue against a major role of the Gly1057Asp IRS-2 polymorphism in the pathogenesis of type 2 diabetes in Djerbian subjects.

Etude de l’association du polymorphisme SNP19 du gène calpaïne 10 avec le diabète de type 2 chez deux groupes ethniques dans la population tunisienne : interaction gène-environnement

Calpaïn 10 (CAPN10) is the first diabetes gene to be identified through a genome scan followed by positional cloning, encoding the cysteine protease, the calpaïn 10 encodes for a ubiquitously expressed protease implicated in the two fundamental pathophysiological aspects of T2DM insulinoresistance and insulinosecretion. Many investigators, but not all, have subsequently found association between calpaïn 10 polymorphism and type 2 diabetes (T2DM) as well as insulin action and insulin secretion. The aim of this study was to determine whether there is an association between specific polymorphism SNP19 in CAPN10 gene and T2DM in two ethnic groups from Djerba Island. Overall, 162 patients with type 2 of diabetes and 110 healthy volunteers who served as controls for genetic characterization with no family history of diabetes were included in the present study. They consisted of 159 women and 113 men. Their mean +/- SD age was 56,47 +/- 11,86 years. All subjects were genotyped according to SNP 19 polymorphism in CAPN10 gene with PCR method to perform case-control study. After adjusting for gender and age, we found an association with a high risk of T2DM in Djerba Island only in Arab sub-group.

Diagnostic and membrane autopsy of Djerba Island desalination station

Tunisia is a semi arid country; the shortage of good water quality in particular at the south regions forced the government to desalt brackish water via membrane technology such as RO to supply these regions with potable water. Station of Djerba Isle established in 2000 by SONEDE has a nominal capacity of 15 ⋅ 103m3 per day and recovery rate of 75%; it is fed from an artesian well with the water salinity of 5500 ppm. Three RO units compose station; each one has configured in two stages a 2:1 array with six RO polyamide elements per pressure vessel. Membranes have been cleaned or replaced, during four operating years, as much time. In the aim to determine the reason of membrane fouling, this work occurs to analyse fouling layers. The membrane autopsy has achieved by different analytical methods, such as COT measurement, SEM (scanning electron microscopy), IR analysis, and diffraction by X-ray. Obtained results show that the deposit composed mostly of organic matter, silica, iron and CaCO3. The debris accumulate on upstream of pressure vessel is composed mainly of silica, metallic matter (iron and chromium) and aluminium phosphate.The presence of TOC indicates the presence of microorganism. The metallic products come from stainless steel fittings and internal coating film of cartridges filter that are damaged by the silica particle probably rejected by sand filters. The scale of CaCO3 deposition is owing to the bad anti-scaling organophosphonate-based, which can form aluminium phosphate by reaction with aluminium composing cartridges filter internal coating.

Spatial patterns of red fox (Vulpes vulpes) dens in a semi-arid landscape of North Africa

African Journal of EcologyVolume 46, Issue 2 p. 168-173 Spatial patterns of red fox (Vulpes vulpes) dens in a semi-arid landscape of North Africa Graziella Lucia Dell’Arte, Corresponding Author Graziella Lucia Dell’Arte *Via Orchidea, 4, 95123 Catania, Italy. E-mail: gresydel@yahoo.itSearch for more papers by this authorGiovanni Leonardi, Giovanni Leonardi Osservatorio Natura, Via Gabriello Carnazza, 27, 95127 Catania, ItalySearch for more papers by this author Graziella Lucia Dell’Arte, Corresponding Author Graziella Lucia Dell’Arte *Via Orchidea, 4, 95123 Catania, Italy. E-mail: gresydel@yahoo.itSearch for more papers by this authorGiovanni Leonardi, Giovanni Leonardi Osservatorio Natura, Via Gabriello Carnazza, 27, 95127 Catania, ItalySearch for more papers by this author First published: 05 September 2007 https://doi.org/10.1111/j.1365-2028.2007.00830.xCitations: 5Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume46, Issue2June 2008Pages 168-173 RelatedInformation

A mutation in LMAN1 (ERGIC-53) causing combined factor V and factor VIII deficiency is prevalent in Jews originating from the island of Djerba in Tunisia.

Combined deficiency of factor V and factor VIII is a rare autosomal recessive bleeding disorder that is caused by mutations in the LMAN1 or MCFD2 genes. These genes encode for proteins that form a complex that takes part in the transport of factor V and factor VIII from the endoplasmic reticulum to Golgi. Two mutations in LMAN1 have been observed in Jews: a guanine (G) insertion in exon 1 among Middle Eastern Jewish families, and a thymidine (T) to cytosine (C) transition in intron 9 at a donor splice site among Tunisian families. For each mutation, haplotype analysis revealed a founder effect. Because all affected Tunisian families belong to an ancient Jewish community in the island of Djerba off the coast of Tunisia, we screened members of this community for the intron 9 T --> C transition. Among 233 apparently unrelated individuals five heterozygotes were detected, predicting an allele frequency of 0.0107 (95% confidence interval, 0.0035-0.0248), while among 259 North African Jews none was found to carry the mutation. The prevalence of the mutation in Djerba Jews is consistent with the observation that all affected Tunisian Jewish families have origins in Djerba and with the finding of a common haplotype for the 9 + 2 T --> C mutation. The G insertion in exon 1 was found in one of 245 Iraqi Jews, predicting an allele frequency of 0.0022 (95% confidence interval, 0.0001-0.0123), but in none of 180 Iranian Jews examined. In view of the relatively low frequency of the mutations in the respective populations it seems reasonable to advocate carrier detection and prenatal diagnosis only in affected families.

THE QUATREFOIL PLAN IN OTTOMAN ARCHITECTURE RECONSIDERED IN LIGHT OF THE “FETHIYE MOSQUE” OF ATHENS

Ottoman architecture celebrated some of its greatest triumphs in three prominently sited Istanbul mosques-the 5ehzade Mehmed mosque (1543-48), the Sultan Ahmed I or Blue mosque (1609-17), and the Yeni Cami (begun in the 1590's, completed in 1666)-built according to the quatrefoil or clover-leaf cross-in-square plan. This plan type gained great popularity, and representative examples of it can be seen from Diyarbakir in southeastern Anatolia to the city of Tunis and the island of Djerba at the extreme western boundary of the Ottoman world, with at least three examples in Greece as an intermediary stage. When in 1833 Muhammad 'Ali started work on his enormous