Samir Touaylia

Altitudinal Distribution of Aquatic Beetles (Coleoptera) in Northern Tunisia: Relationship between Species Richness and Altitude

ABSTRACT n An ecological study of the geographical distribution of aquatic Adephaga and Polyphaga (Coleoptera) in the mountains of northern Tunisia was carried out with an analysis of the effect of altitude on the distribution of 123 species collected from 64 sampling sites. Species richness was analyzed at different altitudinal levels and the indicator species were determined by establishing their altitude profile in terms of reciprocal species-factor information. Species richness decreases with increasing altitude. Thirty representative species are placed into three groups: species present along the entire altitudinal gradient; species present at high altitude; and species occurring at low altitude.

Beetles (Insecta: Coleoptera) as bioindicators of the assessment of environmental pollution

ABSTRACT Bioindicators have been generating great interest in environmental pollution research. Insects and especially arthropod are useful to assess the effects of anthropogenic activities on the terrestrial ecosystem, because they are inclose contact with toxic elements present in soil and in leaf litter. Beetles are extremely sensitive to several ecological parameters, react quickly to environmental modifications and can be easily and cost-effectively sampled by various methods. These criteria make beetles excellent indicators of terrestrial ecosystem. In order to evaluate the environmental impact of human activities on different ecosystems, the use of Coleoptera in ecological studies has been largely increased in recent years. This review presents the results obtained by researchers when using beetles as bioindicators of metallic pollution and forest disturbance.

A study on the family Hydrophilidae Latreille, 1802 (Coleoptera) from Northern Tunisia

Abstract We review the distribution of the water scavenger beetles (Hydrophilidae) in the northern part of Tunisia, based on data from 54 sites collected over the course of a year. In total, 21 hydrophilid species were found. The most interesting ones from the zoogeographical point of view are: Enochrus nigritus Sharp, 1872, Enochrus affinis Thunberg, 1794, Laccobius revelierei Perris, 1864 (all newly recorded for Tunisia), and Laccobius orientalis Knisch, 1924 and Berosus spinosus Steven, 1808 (newly recorded for northern Africa). An updated checklist of hydrophilid species occurring in the northern Tunisia is provided. The composition of the hydrophilid fauna in the area is assessed using the indexes of richness, abundance and diversity. We discuss possible causes of this phenomenon; identify the most valuable water beetle habitats within the investigated area that should be protected by law.

Effect of permethrin (pyrethroid insecticide) on the biochemical response of the freshwater amphipod Echinogammarus tacapensis (Chevreux and Gauthier, 1924)

Abstract Pyrethroids, the widely used pesticides, are highly toxic to aquatic organisms. However, little information is available on their toxicity on crustaceans. We utilized imagoes of Echinogammarus tacapensis to elucidate the effects of sublethal concentrations of permethrin. The LC50 (48, 72, and 96 h) was assessed considering several pesticide concentrations (ranging between 0.5 and 100 ng L−1) using the Regtox package and were found to be 13.88, 8.974, and 4.259 ng L−1, respectively. The biomarkers’ response was analyzed using animals exposed to 0.35, 0.7, and 1.4 ng/L of permethrin for 4 days. The catalase activity was significantly induced after 48 h of exposure to the three permethrin concentrations. Additionally, the glutathione S-transferase activity was increased in a concentration-dependent manner. However, exposed to C1 (0.35 ng L−1), the superoxide dismutase (SOD) activity showed no significant change compared to control values. The hydrogen peroxide (H2O2) rate was found to be similar to the SOD variation. Our findings suggest that permethrin poses a potential threat to freshwater amphipods and thus, the test species can be a useful tool for pesticide toxicity biomonitoring due to their small size, easy husbandry, short life cycle, and high fecundity.

Effects to perfluorooctane sulfonate (PFOS) on the mollusk Unio ravoisieri under laboratory exposure

ABSTRACT To understand acute toxicity and oxidative stress of perfluorinated compounds in the freshwater ecosystems, we exposed freshwater mussels (Unio ravoisieri) to perfluorooctane sulfonate (PFOS), over a range of concentrations from 10 to 100u2005mg/L, in a laboratory experiment. Lethal concentration (LC50) was of about 65.9u2005mg/L after 96u2005h of exposure. The oxidative stress was assessed in gill and digestive gland of the freshwater mussels after 7 days of exposure to different nominal PFOS concentrations (C1=u20092u2005mg/L, C2u2009=u20096u2005mg/L and C3=u200910u2005mg/L). C1 and C2 increased significantly (pu2009<u2009.05) the superoxide dismutase activity in both tissues compared, while the highest C3 decreased the enzyme activity. This implements an unfavourable response that highlights the excess of reactive oxygen species produced after contamination. The Catalase activity was also increased by about 40.05% and 66.63%, respectively, in gill and digestive gland after exposure to C3. The Malondialdehyde (MDA) level was increased in both gill and digestive gland in a concentration-dependent pattern. In contrast, the contamination of U. ravoisieri by PFOS did not affect the acetylcholinesterase activity in both organs (pu2009>u2009.005). These results provided information on potential biomarkers that could be effectively applied for the monitoring of freshwater ecosystem using indicator species such as U. ravoisieri.

Effect of carbaryl (carbamate insecticide) on acetylcholinesterase activity of two strains of Daphnia magna (Crustacea, Cladocera)

ABSTRACT The present study was designed to investigate the effect of carbaryl (carbamate insecticide) on the acetylcholinesterase activity in two strains (same clone A) of the crustacean cladoceran Daphnia magna. Four carbaryl concentrations (0.4, 0.9, 1.8 and 3.7 µg L−1) were compared against control AChE activity. Our results showed that after 48 h of carbaryl exposure, all treatments induced a significant decrease of AChE activities whatever the two considered strains. However, different responses were registered in terms of lowest observed effect concentrations (LOEC: 0.4 µg L−1 for strain 1 and 0.9 µg L−1 for strains 2) revealing differences in sensitivity among the two tested strains of D. magna. These results suggest that after carbaryl exposure, the AChE activity responses can be also used as a biomarker of susceptibility. Moreover, our results show that strain1 is less sensitive than strain 2 in terms of IC50-48 h of AChE activity. Comparing the EC50-48 h of standard ecotoxicity test and IC50-48 h of AChE inhibition, there is the same order of sensitivity with both strains.

Abundance and diversity of the aquatic beetles in a Mediterranean stream system (Northern Tunisia)

Summary. The understanding of community structuring factors is a fundamental issue in community ecology. We investigate the biodiversity of the water beetle in the Ichkeul Lake stream system located in Northern Tunisia, with emphasis on the effect of several environmental variables on their assemblage structure. This area is of a great importance since it was included in the list of preserved waterbodies by RAMSAR convention on wetlands, MAB (Man And Biosphere), UNESCO (United Nations Educational, Scientific and Cultural Organization). Consequently, the study of its biodiversity constitutes a required way to better conduct this protection aim. Special attention must be paid to species endemic to North Africa, as all of them require conservation measures. Sampling was carried out over the course of a year. Dissolved oxygen, conductivity, pH, temperature and turbidity were measured for each study site. Water permanence, velocity, aquatic vegetation and substrate type were considered. The investigated streams showed a spatial heterogeneity in water depth, water velocity, turbidity, mineralization and substrate type, but homogeneity in temperature and dissolved oxygen. A total of 68 coleopteran species were identified from the investigated area, belonging to different chorotypes and phenological categories. The coleopteran assemblage was assessed in terms of four community parameters: abundance, richness (S), diversity (Shannon–Wiener index: H′), and evenness (Pielou index: J′). Species composition was analyzed by multivariate analysis. Sites were arranged into two groups based on their species affinity by non-parametric multidimensional scaling (MDS) ordination on the basis of Bray–Curtis similarity at a similarity of 50%. Principal component analysis (PCA) highlighted the species response to the environmental variables. It revealed the distribution profile of sampled species; on the first axis, F1, a maximum number of variables are projected. Its positive pole is defined by the majority of species, with tolerance of high salinity. On its negative pole only three species are present. Its positive pole is defined by lentic phytophagous species, showing a preference for well vegetated waters. Its negative pole is marked by the species L. orientalis, associated with the majority of water parameters.

Chorological and Phenological Analysis of the Water Beetle Fauna (Coleoptera: Adephaga and Polyphaga) of Northern Tunisia

ABSTRACT Chorological and phenological analyses of the aquatic beetle fauna (Gyrinidae, Haliplidae, Hygrobiidae, Noteridae, Dytiscidae, Hydrophilidae, Hydraenidae, Dryopidae, Elmidae, and Scirtidae) of northern Tunisia are presented. Water beetles were sampled from freshwater ecosystems at 64 sites distributed throughout northern Tunisia. In total, 123 species were identified and their distribution in the study area is discussed. Chorological categories were determined according to the geographical distribution of sampled species. Three groups of species were established based on their phenology: permanent, frequent, and seasonal species.

Effect of the exposure to Mn-doped ZnS nanoparticles on biomarkers in the freshwater western mosquitofish Gambusia affinis

ABSTRACT Synthesized Mn-doped ZnS nanoparticles, with 10% of Mn dopant, were used to investigate their environmental toxicity. Mn-doped ZnS quantum dots (QDs) stabilized by 3-mercaptopropionic acid (MPA) were synthesized in a basic aqueous solution using the nucleation doping. The optical properties and structure of the obtained Mn (10%):ZnS QDs have been characterized by X-ray diffraction, UV–vis, photoluminescence spectroscopies and transmission electron microscopy. The brain, gills and liver stained sections from Gambusia affinis were dissected. Antioxidant enzyme activities (acetylcholinesterase and catalase), as well as malondialdehyde and H2O2 levels, were determined after exposure (94 h) to 14 and 28 mg/L of nanoparticles. The obtained nearly monodisperse Mn(10%):ZnS@MPA QDs have an average diameter of ca. 2.8 nm and a zinc-blende crystal structure. Mn-doped ZnS acts differently on the activities of the biomarkers in a dose-dependent manner. The recorded alterations varied between organs. Such findings provide information on the biological target of nanoparticles and their behaviour within the environment.

Assessment of trace metals contamination in soil, leaf litter and leaf beetles (Coleoptera, Chrysomelidae) in the vicinity of a metallurgical factory near Menzel Bourguiba (Tunisia)

ABSTRACT Metal pollution is a major environmental danger owing to the rapid increase of urbanization and anthropogenic activities, which may damage the fauna and flora. Insects are often used as bioindicators of the accumulation of toxic elements. We measured concentrations of Cu, Fe, Mn, Zn, Al, and Pb in soil, litter and leaf beetles: Oulema gallaeciana (Heyden, 1879) and Lachnaia paradoxa (Olivier, 1808) at four sampling sites at different distances from metallurgical factory near Menzel Bourguiba (Tunisia). Metal concentrations did not extend beyond a distance of 4 km and were restricted to the immediate surroundings. Significant difference between sites was found for Cu, Fe, Al, and Mn concentrations in leaf litter and only for Pb in soil. In the case of Lachnaia paradoxa, no significant differences were found in the contaminant, except for Cu. The concentrations of Fe and Cu were high in Oulema gallaeciana. Positive correlations were detected for metals in the soil, leaf beetles and leaf litter. Our study confirms that the contaminants can transfer from plants to species.