Showing papers by "Lotfi Aleya published in 2017"

Metals and metalloid bioconcentrations in the tissues of Typha latifolia grown in the four interconnected ponds of a domestic landfill site.

Abstract: The uptake of metals in roots and their transfer to rhizomes and above-ground plant parts (stems, leaves) of cattails (Typha latifolia L.) were studied in leachates from a domestic landfill site (Etueffont, France) and treated in a natural lagooning system. Plant parts and corresponding water and sediment samples were taken at the inflow and outflow points of the four ponds at the beginning and at the end of the growing season. Concentrations of As, Cd, Cr, Cu, Fe, Mn, Ni and Zn in the different compartments were estimated and their removal efficiency assessed, reaching more than 90% for Fe, Mn and Ni in spring and fall as well in the water compartment. The above- and below-ground cattail biomass varied from 0.21 to 0.85, and 0.34 to 1.24kgdryweight/m2, respectively, the highest values being recorded in the fourth pond in spring 2011. The root system was the first site of accumulation before the rhizome, stem and leaves. The highest metal concentration was observed in roots from cattails growing at the inflow of the system's first pond. The trend in the average trace element concentrations in the cattail plant organs can generally be expressed as: Fe>Mn>As > Zn>Cr>Cu>Ni>Cd for both spring and fall. While T. latifolia removes trace elements efficiently from landfill leachates, attention should also be paid to the negative effects of these elements on plant growth.

Distribution and assessment of heavy metal toxicity in sediment cores from Bizerte Lagoon, Tunisia

Abstract: To examine the state of pollution of Bizerte Lagoon which is exposed to intense anthropogenic pressure, two sediment cores were taken at two sites, one undergoes the dual effects of both marine waters arriving from the Mediterranean Sea through the Channel, and also of freshwater from the Tinja River; the other core is located at the center of the lagoon where water depth is maximal (12 m). Heavy metal concentrations in the two cores were assessed, with calculated enrichment factors and geo-accumulation indexes. Core sediments were also studied for chemical speciation and their monosulfide contents were measured. Results from enrichment factors and geo-accumulation indexes show an accumulation of Cd, Zn, Cr, and Pb, while chemical speciation revealed a risk only from Cd and Mn. Comparison of sequential extraction values with those of acid volatile sulfides revealed that non-toxic effects may be caused by any of the studied metals in the sediment.

UV-C as an efficient means to combat biofilm formation in show caves: evidence from the La Glacière Cave (France) and laboratory experiments

Abstract: Ultra-violet C (UV-C) treatment is commonly used in sterilization processes in industry, laboratories, and hospitals, showing its efficacy against microorganisms such as bacteria, algae, or fungi. In this study, we have eradicated for the first time all proliferating biofilms present in a show cave (the La Glaciere Cave, Chaux-les-Passavant, France). Colorimetric measurements of irradiated biofilms were then monitored for 21 months. To understand the importance of exposition of algae to light just after UV radiation, similar tests were carried out in laboratory conditions. Since UV-C can be deleterious for biofilm support, especially parietal painting, we investigated their effects on prehistoric pigment. Results showed complete eradication of cave biofilms with no algae proliferation observed after 21 months. Moreover, quantum yield results showed a decrease directly after UV-C treatment, indicating inhibition of algae photosynthesis. Furthermore, no changes in pigment color nor in chemical and crystalline properties has been demonstrated. The present findings demonstrate that the UV-C method can be considered environmentally friendly and the best alternative to chemicals. This inexpensive and easily implemented method is advantageous for cave owners and managers.

First report of the invasive species Branchiomma bairdi McIntosh, 1885 (Annelida: Sabellidae) along the Tunisian coast (Mediterranean Sea)

Abstract: The invasive sabellid polychaete Branchiomma bairdi McIntosh, 1885 was collected in the Boughrara Lagoon (southern Tunisian coast) between 2012 and 2013. This species was originally described from Bermuda and has been widely reported in the Caribbean Sea. It has been considered as non-indigenous species on the Pacific coast of Panama and the California Gulf. Recently, B. bairdi was recorded along the Italian and Turkish coasts, Australia, Canary and Madeira Islands. It was suggested that the commercial shipping is the most likely vector for the introduction of the species to Mediterranean Sea. A description of the species along with a discussion of its systematic position and ecology are provided.

UV-C as a means to combat biofilm proliferation on prehistoric paintings: evidence from laboratory experiments

Abstract: A laboratory investigation of UV-C effects was conducted over a 62-h period: a much higher dose than in classic UV-C treatment was applied to five pigments and two painting binders used by prehistoric humans. Colorimetric parameters were compared to a control to see if UV-C can change pigment and binder color. Infrared spectroscopy, scanning electron microscopy, inductively coupled plasma and X-ray crystallography were also carried out to confirm colorimetric measurement. In order to understand how microorganism may physically deteriorate paintings, limestone blocks were painted and monitored until their complete colonization by algae, cyanobacteria, fungi and/or mosses. The results show that UV-C has no effect on mineral compounds. Conversely, it is noteworthy that binder color changed under both UV-C light conditions as well as in visible light. Concerning painted blocks, a fast proliferation has been observed with deterioration of the paintings. These results show the high importance of treating biofilm as soon as possible. Moreover, these findings may be a promising avenue inducing cave managers to use friendly UV-C light to treat contaminated cave paintings and also in the prevention of biodeterioration by lampenflora.

Assessing ultraphytoplankton and heterotrophic prokaryote composition by flow cytometry in a Mediterranean lagoon

Abstract: In the eutrophic Ghar El Melh Lagoon (GML, Tunisia), the distribution of heterotrophic prokaryotes, pico- and nanophytoplankton was studied at five stations in November 2012 at the single cell level, along with environmental factors. Flow cytometry analysis of ultraplankton (<10 μm) resolved (i) two heterotrophic prokaryote groups, low and high nucleic acid contents (LNA and HNA, respectively), and (ii) eight to nine ultraphytoplankton groups (cryptophyte-like cells, two nanoeukaryote subgroups, two picoeukaryote subgroups and three Synechococcus-like cells subgroups). Prochlorococcus was not detected. According to redundancy analysis (RDA), a significant difference was found in the distribution of the ultraplankton between stations (F = 2.61, p < 0.05); maximum proliferations of heterotrophic prokaryotes were observed in the inner parts of the lagoon at stations 3, 4 and 5 affected by urban, agricultural and industrial discharges. Ultraphytoplankton concentrations were the highest near the outlet of the lagoon at stations 1 and 2 influenced by freshwater outflow and oligotrophic Mediterranean water inflow, respectively. At station 1, the large ultraphytoplankton concentration derives from the high abundance of cryptophyte-like cells favoured by the freshwater outflow whereas at station 2, the input of oligotrophic Mediterranean water enhanced the abundance of Synechococcus and picoeukaryotes at the expense of nanoeukaryotes. Two trophic regimes were thus differentiated in GML.

Artificial wetlands as tools for frog conservation: stability and variability of reproduction characteristics in Sahara frog populations in Tunisian man-made lakes

Abstract: Amphibian populations are in decline principally due to climate change, environmental contaminants, and the reduction in wetlands Even though data concerning current population trends are scarce, artificial wetlands appear to play a vital role in amphibian conservation This study concerns the reproductive biology of the Sahara frog over a 2-year period in four Tunisian man-made lakes Each month, gonad state (parameters: K, GSI, LCI), fecundity, and fertility of females (using 1227 clutches) were evaluated in the field under controlled conditions Clutches were present for 110–130 days at two of the sites, but only for 60–80 days at the other two Maximum egg laying occurred in May, corresponding to the highest point in the gonad somatic index Clutch densities were higher in the smaller lakes Female fecundity was in relation to body size; mean clutch fecundity attained 1416 eggs, with no differences observed according to site Egg fertility varied over a 1-year period, with a maximum in May followed by a decrease when water temperature was at its highest Eggs were smaller at the beginning of spawning; maximum size was in May, which might explain the higher fertility, but no maternal influence was detected Embryonic development was strictly dependent on temperature The population at each site appeared as a small patch within a metapopulation in overall good health, as shown by the relative temporal stability in reproduction variables Constructed wetlands may therefore play an important role in the conservation of amphibians, especially in semi-arid zones

Optimization of fishing for stock enhancement of Rutilis rutilus and Scardinius erythropththalmus in forage fish-deficient Tunisian reservoirs

Abstract: Twenty specially designed fishing nets were used to catch broodstock of the forage fish roach and rudd (Rutilus rutilus and Scardinius erythrophthalmus). The monofilament gill nets were of different mesh sizes (18, 22, 24, and 26 mm) but of identical dimensions (4 × 50 m). The fish, caught in Sidi Salem reservoir in 2014, amounted to a total of 8901 roach and rudd caught at 41 different times; 3335 broodstock forage fish were transferred to 11 forage fish-deficient Tunisian reservoirs. The best yields (0.464 fish/m2) were obtained with fishing gear fitted with 18-mm mesh size; however, fish mortality with this net was very high, exceeding 83.36%. The greatest efficiency was obtained using nets of 22- and 24-mm mesh with a number of fish per unit effort (NPUE) of 0.181 and 0.173 fish/m2, and a mortality of 54.34 and 53.85%, respectively. Gill nets of 26-mm mesh size were inappropriate (lowest yield 0.129 fish/m2). Length of rudd and roach at first maturity and Gonadosomatic index (GSI) were measured, indicating that all transferred fish were mature. Transfer techniques were improved by holding the captured fish for 5 days before release into the host reservoir.

UV-C as an Efficient Means to Combat Biofilm Formation in Cultural Heritage Monument. Biodiversity and Impact on Prehistoric Pigments?

Abstract: 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 ecological and efficient method to eradicate photosynthetic biofilms. Our previous works showed the good efficiency of UV-C against biofilms. To ensure the safety of UV-C treatment, pigments used for prehistoric parietal painting were strongly irradiated around 4800 kJ m−2. Afterward, we treated all biofilms in La Glaciere show cave. Following the treatment, irradiated biofilm color evolution was monitored. Results of sequencing showed that biofilms were mainly composed of bacteria, fungi, cyanobacteria, chlorophyceae, and diatoms. Multicellular mosses were also present in each biofilm. Furthermore, X-ray crystallography, infrared spectroscopy, and colorimetric measurement showed no change in pigment color nor in their chemical structure. Finally, UV-C treatment results showed that biofilms were completely eradicated with no algae proliferation observed after 21 months. Moreover, a complete bleaching is obtained with UV-C, which is not always the case with chemical conventional methods. In conclusion, the use of UV-C could be considered as an environmentally friendly good alternative to chemical products. Moreover, microorganisms are killed by radiation, while no change in pigment color nor in their chemical structure has been observed.