0000000000075326
AUTHOR
Lotfi Aleya
Assessment of surface sediment dynamics and response of benthic macrofauna assemblages in Boughrara Lagoon (SW Mediterranean Sea)
International audience; 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 move…
Structuring factors of the spatio-temporal variability of macrozoobenthos assemblages in a southern Mediterranean lagoon: How useful for bioindication is a multi-biotic indices approach?
International audience; The authors investigated the impact of the extension of the El Kantra Channel on the composition and structure of macrobenthic assemblages in Boughrara Lagoon (Gulf of Gabes, Tunisia along with the use of 4 biotic indices (AMBI, BENTIX, M-AMBI and TUBI). Thirteen stations were sampled seasonally in 2012–2013. Forty-one species were found in 2012–2013 not recorded in 2009–2010, including 20 species of polychaetes belonging to the trophic groups of deposit-feeders and carnivores which are expected to increase in areas disturbed by organic pollution. During the survey, we recorded a high fish mortality, essentially caused by the development of harmful algal blooms (HAB)…
Carbon, iron and sulphur cycling in the sediments of a Mediterranean lagoon (Ghar El Melh, Tunisia)
Coastal lagoon sediments are important for the biogeochemical carbon cycle at the land-ocean transition, as they form hotspots for organic carbon burial, as well as potential sites for authigenic carbonate formation. Here, we employ an early diagenetic model to quantify the coupled redox cycling of carbon, iron and sulphur in the sediments of the shallow Ghar El Melh (GEM) lagoon (Tunisia). The model simulated depth profiles show a good correspondence with available pore water data (dissolved inorganic carbon, NH 4 + , total alkalinity, Ca 2+ , Fe 2+ and SO 4 2− ) and solid phase data (organic matter, pyrite, calcium carbonate and iron (oxyhydr)oxides). This indicates that the model is abl…
Aspects of excessive antibiotic consumption and environmental influences correlated with the occurrence of resistance to antimicrobial agents
International audience; This article explores the correlation between specific aspects of antibiotic usage, their resistance development, and environmental factors. The indiscriminate use of antibiotics led to environment contamination, selection and spreading of antibiotic-resistant organisms, and alteration of the microbial ecosystems balance. Sociobehavioural environmental factors and changes in the natural environment are major contributors to resistance development. Resistant bacteria strains' isolation in food, water, soil etc. demonstrates the environmental influence on the strains through antibiotics accumulation in the environment. It is difficult to assess the impact of antibiotic…
Environmental Quality Assessment of Bizerte Lagoon (Tunisia) Using Living Foraminifera Assemblages and a Multiproxy Approach.
This study investigated the environmental quality of the Bizerte Lagoon (Tunisia) through an integrated approach that combined environmental, biogeochemical, and living benthic foraminiferal analyses. Specifically, we analyzed the physicochemical parameters of the water and sediment. The textural, mineralogical, and geochemical characteristics of the sediment, including total organic carbon, total nitrogen, simultaneously extracted metals (SEM), acid volatile sulfides (AVS), chlorophyll a, CaCO3, and changes in bacterial populations and carbon isotopes were measured. The SEM/AVS values indicated the presence of relatively high concentrations of toxic metals in only some areas. Foraminiferal…
Immuno-toxicological Evaluation of the Adjuvant Formulations for Experimental Anti-meningococcal Vaccines without Aluminium Hydroxide
International audience; The proteoliposomes and cochleates are used as adjuvants for vaccines since they are potent immune stimulators. However, the hyper stimulation of the immune system provoked by adjuvants can cause immunetoxicological side effects. The present study was carried out to evaluate the toxic and immuno-toxicological effects of new adjuvants for anti-meningococci vaccines based on neo-proteoliposomes (nPL) and neocochleates (nCh), in Balb/c mice that were administered doses of 15 µg each, over periods of 14 days through intramuscular route and three inoculations with the same doses through intranasal route, every 7 days. The Scanning and Transmission Electron Microscopy show…
The mapping of the Posidonia oceanica (L.) Delile barrier reef meadow in the southeastern Gulf of Tunis (Tunisia)
Abstract Barrier reefs are among the most important ecomorphosis for Posidonia oceanica meadows and have long been subjected to anthropic pressures. The authors mapped the entire Sidi Rais (northeastern Tunisia) Posidonia oceanica barrier reef by means of remote sensing based on processing a satellite image acquired via Google Earth © software, coupled with field observations obtained by snorkeling. The map thus produced represents the P. oceanica barrier reef in its current state, covering a total area of 156.77 ha, the reef being divided into three distinct sections separated by reverse flows with each section subject to varied anthropic factors and disturbances.
Accumulation of trace metals in sediments in a Mediterranean Lagoon: Usefulness of metal sediment fractionation and elutriate toxicity assessment.
International audience; The authors investigated sediment quality in Bizerte Lagoon (Tunisia) focusing on geochemical characteristics, metal sediment fractionation and elutriate toxicity assessment. Nickel, Cu, Zn, Pb, Cr and Cd partitioning in sediments was studied; accumulation and bioavailability were elucidated using enrichment factors, sequential extractions, redox potential, acid volatile sulfide and biotest procedures in toxicity evaluation. Results revealed an accumulation for Pb and Zn, reaching 99 and 460 mg kg−1 respectively. In addition, the acid volatile sulfide values were high in both eastern and western lagoon areas, thus affecting metal availability. Mean enrichment factor …
Suspended particulate matter fluxes along with their associated metals, organic matter and carbonates in a coastal Mediterranean area affected by mining activities
International audience; A study of suspended particulate matter (SPM) fluxes along with their associated metals, organic matter and carbonates, was conducted off the Mejerda River outlet in May 2011 and in March and July 2012 at depths of 10, 20 and 40 m using sediment traps. SPM fluxes are more significant near the Mejerda outlet, especially in winter, but dissipate further offshore. Normalization reveals that the Mejerda is a major source of Pb, Zn, Cd, Cu, Ni, and Co, all of which are the result of human activities. In contrast, Fe, Mn and N are of authigenic origin. The enrichment factor shows that Pb, Zn and especially Cd are the most highly polluting metals off the Mejerda outlet. Thi…
Dynamics of sediments along with their core properties in the Monastir-Bekalta coastline (Tunisia, Central Mediterranean)
International audience; The authors report on two campaigns of high-resolution samplings along the shores of Monastir Bay in Tunisia: the first being a study of sediment dynamics, grain size and mineral composition in surface sediment, and the second, eight months later, using four sediment cores to study grain-size distribution in bottom sediments. Particle size analysis of superficial sediment shows that the sand in shallow depths is characterized by S-shaped curves, indicating a certain degree of agitation, possible transport by rip currents near the bottom and hyperbolic curves illustrating heterogeneity of sand stock. The sediments settle in a relatively calm environment. Along the bay…
Comparison of biocides, allelopathic substances and UV-C as treatments for biofilm proliferation on heritage monuments
Abstract UV-C and biocide treatments are frequently used to treat historical monuments contaminated by autotrophic biofilms. In this study, the authors compare for the first time the efficacy of these treatments against microorganisms such as cyanobacteria and algae proliferating in the Vicherey church (Vicherey, Vosges Department, France). To identify the most environmentally friendly and also efficient method, an allelopathic treatment was also tested. Colorimetric and physiological measurements of treated biofilms were thus monitored for 6 months. Fungi growing on necrotic matter from treated biofilms were sampled and sequenced. With biocides, results showed incomplete eradication of bio…
Chemical speciation of Fe, Mn, Pb, Zn, Cd, Cu, Co, Ni and Cr in the suspended particulate matter off the Mejerda River Delta (Gulf of Tunis, Tunisia)
International audience; Fluxes of suspended particulate matter (SPM) and their associated metals were performed off the Mejerda River Delta during both the wet (March) and the dry (July) seasons in 2012, using sediment traps at study stations at depths of 10, 20 and 40 m. Fluxes nearest to the Mejerda outlet were more significant, especially during winter (36 g m−2 day−1), but dissipated further offshore, 24.5–6 g m−2 day−1 at the 20 m and 21.8–4.8 g m−2 day−1 at the 40 m stations. Many variations observed in seasonal and spatial metal fluxes are similar to those of SPM, in particular Pb and Zn, probably because they are associated with the mining activity characteristic of the Mejerda catc…
High-resolution numerical modelling of the barotropic tides in the Gulf of Gabes, eastern Mediterranean Sea (Tunisia)
International audience; A high-resolution 2D barotropic tidal model was developed for the Gulf of Gabes and used to characterise hydrodynamic processes and tidal dynamics. The model is based on the Regional Ocean Modelling System. It is forced at the open boundaries by the semidiurnal M2 and S2 astronomical components while meteorological forcing has been neglected. The model results show good agreement with observations confirming that it reproduces the gulf's main tidal characteristics reasonably well. In fact, the simulated semidiurnal tidal components M2 and S2 generate important sea level variations and coastal currents. Tidal propagation is directed to the gulf's western sector while …
UV-C as an Efficient Means to Combat Biofilm Formation in Cultural Heritage Monument. Biodiversity and Impact on Prehistoric Pigments?
Caves are considered oligotrophic habitats exhibiting constant temperature and relative humidity throughout the year. While darkness inhibits photosynthetic microorganism growth, introducing artificial lights to promote touristic activity can induce algae and cyanobacteria proliferation. Besides the aesthetic problem, microorganisms are responsible of physical and chemical degradation of limestone wall with possibly a degradation of prehistoric painting of cultural value. In our studies, we identified lampenflora with new-generation sequencing (NGS) in five French show caves and also on a 180, 000 years old contaminated bear bones (Ursus deningeroides). Afterward, we attempted to find an ec…
The Effects of Oregano Oil on Fungal Infections Associated with Metabolic Syndrome
International audience; This study aims to compare the evolution of mycosis associated with metabolic syndrome under allopathic treatment compared to phytotherapy using oregano essential oil. The study was conducted over a period of 6 months, on a total of 72 patients diagnosed with fungal infections associated with metabolic syndrome. The patients were divided into 3 groups, depending on the administered treatment: group 1: 24 patients who received allopathic treatment; group 2: 24 patients who received oregano oil treatment; group 3: control, which did not undergo any antifungal treatment. All three groups were subjected to specific diet therapy for mycosis. The patients were initially ev…
Bioavailability and assessment of heavy metal pollution in sediment cores off the Mejerda River Delta (Gulf of Tunis): How useful is a multiproxy approach ?
International audience; Three core samples were taken from zones offshore from the Mejerda River Delta (Tunisia) and analyzed formajor and trace elements to assess their relationships with organic matter, monosulfides and carbonates, aswell as for pollution and bioavailability. Chemical speciation,ΣSEM/AVS, the enrichment factor (EF) and thegeo-accumulation index (I-geo) were used. Iron, cadmium, lead and zinc – the most frequently mined metalsin the Mejerda catchment – were found as contaminants in the offshore areas. Estimations of trace elementaccumulation using the EF and the I-geo index show that lead, and to a lesser extent zinc, are the most pollutingmetals off the Mejerda outlet. Ac…
GEOCHEMICAL AND MINERALOGICAL FINGERPRINTS OF THE SEDIMENTS SUPPLY AND EARLY DIAGENETIC PROCESSES IN THE BIZERTE LAGOON (TUNISIA)
International audience; The Bizerte Lagoon (Tunisia) functions as a sedimentation environment characterized by receiving allochthonous sediments mainly transported by the Ben Hassine, Rharek and Guenich streams, as well as marine sediments from the Mediterranean Sea. It is subjected to significantenvironmental changes due to the natural and anthropic influences altering the natural patterns of circulation, extraction and/or deposition of mineralogical materials. The aim of this investigation is to analyze the sediments supply and early diagenetic processes in Bizerte Lagoon. Thephyicochemical parameter of the sediment pore water, as well as their texture, mineralogical composition (X-Ray di…
Biofilm biodiversity in French and Swiss show caves using the metabarcoding approach: First data.
International audience; In recent decades, show caves have begun to suffer from microorganism proliferation due to artificial lighting installations for touristic activity. In addition to the aesthetic problem, light encourages microorganisms that are responsible for physical and chemical degradation of limestone walls, speleothems and prehistoric paintings of cultural value. Microorganisms have previously been described by microscopy or culture-dependent methods, but data provided by new generation sequencing are rare. The authors identified, for the first time, microorganisms proliferating in one Swiss and in four French show caves using three different primers. The results showed that bo…
Assessment of Physical and Chemical Stability of Different Magnesium Compounds in Tablets
Modern lifestyle, excessive chemicalization of agricultural products, excessive processing and refining of food, cause a decrease in daily intake of magnesium, cation with an extremely important role in prevention and treatment of many diseases. As a result, there arises the need for extra magnesium intake in the form of dietary supplements. In this study were evaluated the physical and chemical stability of magnesium-containing tablets, depending on the active compound and the excipients used. Magnesium tablets in the form of orotate, lactate, citrate, oxide and hydroxide were taken into study and physical and chemical stability were observed over the validity period, at 6 and at 12 month…
Alexandrium pacificum Litaker sp. nov (Group IV): Resting cyst distribution and toxin profile of vegetative cells in Bizerte Lagoon (Tunisia, Southern Mediterranean Sea)
International audience; A high spatial resolution sampling of Alexandrium pacificum cysts, along with sediment characteristics (% H2O, % organic matter (OM), granulometry), vegetative cell abundance and environmental factors were investigated at 123 study stations in Bizerte Lagoon (Tunisia). Morphological examination and ribotyping of cells obtained from a culture called ABZ1 obtained from a cyst isolated in lagoon sediment confirmed that the species was A. pacificum. The toxin profile from the ABZ1 culture harvested during exponential growth phase was simple and composed of the N-sulfocarbamoyl toxins C1 (9.82 pg toxin cell−1), the GTX6 (3.26 pg toxin cell−1) and the carbamoyl toxin Neo-S…
Random Forest model and TRIX used in combination to assess and diagnose the trophic status of Bizerte Lagoon, southern Mediterranean
International audience; A combined multimetric trophic index (TRIX) and the Random Forest (RF) model were used to characterize the trophic status of Bizerte Lagoon. The RF model was used to build a predictive model of chlorophyll a using physicochemical variables (nitrite, nitrate, ammonium, phosphate, oxygen, temperature and salinity) as predictors. The approach is based on physicochemical and biological parameters measured in samples collected twice weekly from January to December 2012 at one representative sampling station located at the lagoon center.The observed TRIX values vary from 5.18 to 6.12, reflecting waters ranging from moderate to poor quality with a high trophic level. The re…
Trace element accumulation and elutriate toxicity in surface sediment in northernTunisia (Tunis Gulf, southern Mediterranean)
International audience; Metal concentrations in sediments were investigated in the Gulf of Tunis, Tunisia, in relation to anthropic activities along the Mejerda River and Ghar El Melh Lagoon, with effluents discharged into the gulf. Distribution of grain size showed that the silty fraction is dominant with 53%, while sand and clay averages are 34 and 12% respectively. Zn concentration increased in the vicinity of the Mejerda River while Pb was at its highest levels at the outlet of Ghar El Mehl Lagoon. Sediment elutriate toxicity, as measured by oyster embryo bioassays, ranged from 10 to 45% abnormalities after 24 h, but no relation was found between metal concentration and sediment toxicit…
Spatial characterization of leachate plume using electrical resistivity tomography in a landfill composed of old and new cells (Belfort, France)
International audience; Located near Belfort (France), the Etueffont landfill was in operation from 1976 to 2002 for the disposal and storage of domestic waste produced by 47,650 inhabitants. The site is comprised of the original landfill site called the old landfill (OL), in operation from 1976 to 1999, and a newer section known as the new cell (NC) which operated from 1999 to 2002. The objective of this study is to determine, using electrical resistivity tomography (ERT), the extent of the leachate plume from the OL and to monitor the efficiency of the liner of the NC. The entire Etueffont site was crisscrossed with 21 electrical profile lines which were traced in summer between 2009 and …
Barrier properties of anti-gas military garments, considering exposure to gas organic compounds
The problems of determining the protective properties of barrier materials used for the production of body surface protection products of an isolative type are very actual. These garments are expected to have long-term resistance against permeation of toxic substances. The paper deals with the study of the effect of organic solvent vapours on the changes in protective properties of selected anti-gas protective garments commonly used by the North Atlantic Treaty Organization armed forces. Permeation measurements of selected gases with integral permeameter were performed to verify their barrier properties, surface changes after exposure to selected solvents by using a 3D optical profilometer,…
Neuroplasticity and environment: A pharmacotherapeutic approach toward preclinical and clinical understanding
International audience; Emerging research in the field of behavioral neuroscience has demonstrated the fundamental role of the cerebral organization. For brain development, various important functions are required for instance synaptic plasticity and neurogenesis. This property is described in terms of neuroplasticity. Neuroplasticity denotes the extraordinary ability of the brain for the recognition of its structure and function after an experience with some external stimuli and involves in the various behavioral processes of the brain such as cognitive functions. It has multiple factors that can range from gene alteration to environmental factors. Environmental factors exert both negative…
Machine learning predictions of trophic status indicators and plankton dynamic in coastal lagoons
Abstract Multivariate trophic indices provide an efficient way to assess and classify the eutrophication level and ecological status of a given water body, but their computation requires the availability of experimental information on many parameters, including biological data, that might not always be available. Here we show that machine learning techniques – once trained against a full data set – can be used to infer plankton biomass information from chemical and physical parameter only, so that trophic index can then be computed without using additional biological data. More specifically, we reconstruct plankton information from chemical and physical data, and this information together w…
Driving factors of dinoflagellate cyst distribution in surface sediments of aMediterranean lagoon with limited access to the sea
International audience; Seasonal distribution of dinoflagellate cysts were studied at five surface sediment study stations in Ghar El MelhLagoon (GML) (Tunisia) in relation to physicochemical parameters and phytoplankton abundance in the watercolumn. At least sixteen dinocyst types were identified, dominated mainly by Protoperidinium spp., Scrippsiellatrochoidea complex, Lingulodinum machaerophorum, Alexandrium spp. and Gymnodinium spp., along with manyround brown cysts. Cyst abundance ranged from 0 to 229 g−1 dry sediment. No significant differences in cyst distributionwere found among stations, though a significant variation was observed among seasons with cyst dominancein autumn. No sign…
Surface sediment dynamics along the Tunisian coast at Skhira (Gulf of Gabès, south-eastern Tunisia)
Abstract An investigation was conducted in the summer of 2012 at 24 study stations along the Tunisian coast near Skhira (south-eastern Mediterranean Sea) through high resolution of analyses, grain size and mineral composition of surface sediment. An Acoustic Doppler Current Profiler showed Skhira's main coastal current to follow a direction 60°E, with its main axis south-west/north-east parallel to the coastline and its minor axis east-west. Current speeds were approximately 13 cm s−1 and 4.5 cm s−1 for the major and minor axes, respectively. Parallel to the coast, currents were generally mild to moderate, but often exceeded 20 cm s−1. An Argonaut meter recorded the dominant current directi…
Protecting emergency workers and armed forces from volatile toxic compounds: Applicability of reversible conductive polymer-based sensors in barrier materials
International audience; Barrier materials have wide applicability in both professional (military, medical, industrial) and non-professional(leisure and sports) fields. This paper focuses on the preparation of real conductive polymer (CP) sensors, for thestudy of the permeation of volatile toxic compounds through barrier materials. Use of such a CP sensor can helpimprove the quality of barrier materials used in protective clothing. Several types of platforms have beenmanufactured or purchased for use as comb sensors with different electrode dimensions, and a suitable methodof applying the detection layer of conductive polymers (polyaniline and poly-pyrrole) has been developed. Prepared senso…
Surface sediment dynamics along the shore of Hammamet Gulf (Tunisia, southern Mediterranean)
International audience; In the summer of 2015 the authors analysed grain size and surface sediment composition through high spatial resolution from samples taken at 53 stations along the Hammamet coast (southern Mediterranean Sea). The Acoustic Doppler Current Profiler deployed in this study showed that the surface current flows toward the north-east, parallel to the coast at a maximum speed along the main axis of about 5.9 cm s−1. Near the bottom the current flows toward the north-west at a maximum speed of 2.2 cm s−1. The tide plays a relatively small role in water circulation in Hammamet Gulf. Spatial distribution of particle size, along with speed and current direction analysis, furnish…
Assessment of fungi proliferation and diversity in cultural heritage: Reactions to UV-C treatment.
International audience; Fungi are present in natural and non-touristic caves due to the presence of organic matter provided mainly by insects or animals such as bats. In show caves, however, tourist infrastructure and the visitors themselves are an important source of organic matter. In addition, photosynthetic biofilms provide a high amount of carbon and nitrogen sources for fungi. This study was conducted to identify the fungal communities present in caves along with the potential use of UV-C treatment against their proliferation. Thus, fungal communities proliferating in biofilms in six French and Swiss show caves were analyzed using high throughput sequencing. The results show 385 speci…
Consequences of analgesics use in early pregnancy: Results of tests on mice.
International audience; Self-medication during pregnancy continues to be an issue in developing countries due topoor medical education. The most commonly used drugs are analgesics, mainlyacetaminophen (paracetamol, APAP) and, to a lesser extent, ketoprofen (KPF). The aim of thestudy was to establish whether there are consequences of accidental use of these two drugsduring early embryogenesis. The experimental study was performed on 30 pregnant whitemice, divided into three groups: a first group to which APAP was administered, a secondgroup to which KPF was administered, and group 3 as a control group. At delivery, the babymice were examined, and after their first parturition, they were take…
Possible functions of biomineralization of some Textulariid (Foraminifera) species of the Nw Iberian Margin
The main goal of this work is to analyze the elemental composition of the test’s wall of some species/specimens of Textulariids (sub-class Subclass Textulariia), collected in surface sediments of the NW Iberian Margin. The elemental analyses was based on the Energy Dispersive Spectroscopy (EDS) on the Scanning Electron Microscope (SEM; Hitachi, S4100) of Textularia deltoidea, Textularia agglutinans, Sahulia conica, Karrerotextularia flintii, Siphotextularia heterostoma, Karreriella bradyi, Spiroplectammina sagittula and Arenoparrella mexicana . The elelemetal cocnentrations of the species wall were compared with the mineralogical composition (X-Ray diffraction) of the sediments of the stati…
Assessing surface sediment dynamics along the north-west coast of Marsa Dhouiba (Tunisia, southern Mediterranean)
International audience; An investigation was conducted from summer 2012 to winter 2013 at 25 stations along the Tunisian coast near Kef Abbed at Marsa Dhouiba (north-east Mediterranean Sea) to analyse grain size, sediment mineralogy and currents. Particle-size analysis shows that sand deposits at shallow depths are characterised by S-shaped curves, indicating a degree of agitation and possible transport by rip currents near the bottom. At greater depths (between 10 and 30 m), the bottom is covered by coarse sand and gravel. A current was observed transporting sediment eastward along the coast; another seaward current was also noted. Generated by wind, swell and especially waves from west to…
Variations in the Chemical Composition of the Essential Oil of Lavandula angustifolia Mill., Moldoveanca 4 Romanian Variety
International audience; In this research, the variations in the chemical composition of the Lavandula angustifolia Mill. essential oil, the Romanian variety Moldoveanca 4, obtained from the same culture, in the same harvesting and extraction conditions, during the years 2016-2018, representing the years 2-4 of culture. Lavandula angustifolia Mill. flowers were supplied from an ecological-crops from N-E Romania and the essential oils were obtained by hydro distillation of freshly harvested flowers. To determine the chemical composition, the essential oil was semi-quantitatively analysed by using gas chromatography coupled with mass spectrometry (GC-MS). In all the samples, 30 organic compoun…
Overview of pesticide use in Moroccan apple orchards and its effects on the environment
International audience; The cultivation of apple trees needs to use phytosanitary products, which are used in an irrational way by certain farmers. The harmful effects of pesticides result mainly from their persistence in the environment. Several studies have been carried out to estimate the pesticide residues and assess their effects on soil microorganisms and aquatic organisms. The results of these studies have revealed a harmful effect on these bioindicators. Therefore, a disruption in their growth and reproduction, an increase in their mortality, and a decrease in their fertility have been proven. In addition, a considerable reduction in the number and diversity of soil microorganisms a…
Spatial distribution, contamination assessment and potential ecological risk of some trace metals in the surface sediments of the Gulf of Tunis, North Tunisia
To evaluate the trace metals contamination status in the Gulf of Tunis, forty one sediment samples were analyzed using different approaches. According to certain contamination and ecological risk indices (Contamination Factor, Geoaccumulation index and Ecological risk index), Hg has the highest contamination level while pollution by Ni, Pb, Cd and Cr was absent. The highest concentrations of trace metals were found in sediments collected from the offshore and coastal areas located opposite the main exchange points with the gulf particularly, the Mejerda and Meliane Rivers, the Khalij Channel, Ghar El Melh and El Malah lagoons, Tunis Lake and Sebkhat Ariana. However, further ecological indic…
Organic matter quantity and quality, metals availability and foraminiferal assemblages as environmental proxy applied to the Bizerte Lagoon (Tunisia)
International audience; This study analyzes the benthic trophic state of Bizerte Lagoon (Tunisia) based on the total organic matter and the bioavailability of biopolymeric carbon including proteins (PTN), carbohydrates (CHO), lipids (LIP), chlorophyll a, as well as bacteria counts. The overall simultaneously extracted metals (SEM), and acid volatile sulfides (AVS) as well as the SEM/AVS ratio indicative of the toxicity of the sediments also were analyzed aiming to study their impact in the dimension, composition and structure of both dead and living benthic foraminiferal assemblages.In the studied sites TOC content is relatively high and the PTN/CHO values indicate that they can be consider…
Ultra- and microplankton assemblages as indicators of trophic status in a Mediterranean lagoon
International audience; The seasonal abundance distribution of heterotrophic prokaryotes, pico-and nanophytoplankton, was investigated in connection with environmental variables and microplankton abundance at five stations in Ghar El Melh Lagoon (northeastern Tunisia). Flow cytometry analysis of ultraplankton resolved (i) five heterotrophic prokaryote groups labelled LNA1, LNA2 (low nucleic acid content), HNA1, HNA2 and HNA3 (high nucleic acid content) and (ii) at least 14 ultraphytoplankton groups assigned to picoeukaryotes, picoprokaryotes, nanoeukaryotes, cryptophyte-like cells and some unknown communities. Redundancy analysis (RDA) revealed (i) autumn-summer outbreaks of heterotrophic p…