Mustapha Bejaoui

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

ABSTRACT 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.

Qualité des eaux du cours principal de la Medjerda (Tunisie et Algérie) et trois de ses affluents Nord

Résumé Une étude a été effectuée dans la zone Nord-Ouest du bassin versant de la Medjerda avec pour objectif de fournir de nouvelles connaissances sur la qualité des eaux ainsi que sur le type de relation qui peut exister entre les variables physico-chimiques, bactériologiques et les indices de diversité/densité de la méiofaune. Les résultats montrent une dégradation de la qualité du cours principal de la Medjerda et de trois de ses affluents Nord (augmentation de la salinité, teneur en nitrate, matière organique, coliformes…). Les indices de diversité et d’équitabilité suivent cette évolution régressive des variables physico-chimiques et apportent de nouvelles connaissances sur le type et la qualité du sédiment. Editeur Z.W. Kundzewicz ; Editeur associé B. Touaïbia

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.

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.

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.

Biodiversity of Ground Beetles (Coleoptera: Carabidae) from Northern Tunisia

ABSTRACT:  The family Carabidae is an important group of mostly terrestrial predators in the order of Coleoptera. Their diversity and assemblage structure were analyzed using samples obtained from six localities in northern Tunisia using pitfall traps. Species richness and abundance of carabids in different habitat types (forests, parks and cultivated fields), and their relationship with the environment were discussed. A total of 840 carabid beetles belonging to 39 species were collected. An analysis of site similarity based on species richness showed spatial variation. The Shannon-Wiener diversity and evenness indexes were calculated. The most abundant taxa were Chlaenius chrysocephalus (Rossi, 1790), Carterus rotundicollis (Rambur, 1842) and Amara aenea (De Geer, 1774). Non-metric multidimensional scaling (NMDS) ordination highlighted the faunistic affinities among sites revealing three main groups. Temperature, rainfall, soil organic matter content, altitude and abundance of vegetation seem to be the major drivers structuring beetle assemblages and influencing species abundance and richness. These results suggest that habitat heterogeneity was the predictor of beetle assemblages, while species richness could be expected at a landscape scale using abiotic features.

Cyclomorphosis in Daphnia magna and Ceriodaphnia reticulata (Cladocera) from northern Tunisian groundwater: influence of temperature and invertebrates?

In the present study, we investigated cyclomorphosis in two cladocerans, Daphnia magna and Ceriodaphnia reticulata , sampled from northern Tunisian groundwater (wells) during two seasons (spring and summer). Seasonal distribution of the two species was apparent, with dominance of D. magna only in spring and C. reticulata during the whole study period. Our results showed correlations between caudal spine length of D. magna and water temperature ( r = 0 . 95 , p = 0 . 002 ), and between caudal spine length and the density of coleopteran larvae ( Stictonectes escheri , Graptodytes sp., Gyrinus urinator , and Haliplus lineaticollis ) ( r = 0 . 98 , p = 0 . 0005 ). In C. reticulata , we registered a correlation ( r = 0 . 95 , p = 0 . 003 ) only between its size and the density of larvae of Ephemeroptera ( Cloeon cognatum ) but no correlation with water temperature was found.