Amor Hedfi

Mussel-farming effects on Mediterranean benthic nematode communities

Mussel aquaculture activities in coastal areas are growing rapidly throughout the world, inducing an increasing interest and concern for their potential impact on coastal marine environments. We have investigated the impact of organic loads due to the biodeposition of a mussel farm in a lagoonar ecosystem of the Mediterranean Sea (Bizerta lagoon, northern Tunisia) on the benthic environment. The most evident changes in the benthic habitat under the farm were a strong reduction of oxygen penetration into the bottom sediments and a large accumulation of chlorophyll a (concentrations up to 16 μg g–1), phaeopigments (concentrations up to 48 μg g–1) and total organic matter (concentrations up to 12%). Results from univariate analysis of the nematofaunal data show that the nematode abundance increased in all the stations located inside the mussel farm (I1, I2, I3) and the site I2, located in the centre of the mussel farm, was the most affected. At this site, Shannon-Wiener index H′, species richness (d), evenness (J′) and number of species (S) decreased significantly. Results from multivariate analyses of the species abundance data demonstrated that responses of nematode species to the organic matter enrichment were varied: Mesacanthion diplechma was eliminated at the most affected station (I2), whereas the abundances of Paracomesoma dubium, Terschellingia longicaudata and T. communis were significantly enhanced. Responses of free-living nematodes to mussel farm biodeposition (elimination of some species and increase or decrease of some others) could lead to food limitation for their predators that, ultimately, could alter entire communities and ecosystems. Consequently, we suggest that site-specific hydrodynamic and biogeochemical conditions should be taken into account when planning new mussel farms, and meiobenthic communities should be monitored before and after farm development to prevent excessive modifications of benthic assemblage structure.

Bats of Jebel Mghilla National Park (central Tunisia): first survey and habitat-related activity

We surveyed the bat fauna of the Jebel Mghilla National Park (central Tunisia) in the five main habitats from the lowland to the summit: cultivated area, open juniper (Juniperus spp.) forest, Stipa tenacessima steppe, open and dense forest of Pinus halepensis, with a special emphasis on water bodies. We mist-netted three bat species: Eptesicus isabellinus, Myotis emarginatus and Myotis punicus. We also identified echolocation calls of Rhinolophus blasii, Rhinolophus ferrumequinum, Rhinolophus hipposideros, Tadarida teniotis, Miniopterus schreibersii, Pipistrellus kuhlii, Plecotus gaisleri and Hypsugo savii. Pipistrellus kuhlii and E. isabellinus were the most active and widely distributed species. The bat fauna was richer in the dense and open pine forest than in cultivated area and open juniper forest, but water bodies are also very attractive for bats.

Investigation of Antiulcer and Antioxidant Activity of Juniperus phoenicea L. (1753) Essential Oil in an Experimental Rat Model

Juniperus phoenicea is a tree of the Cupressaceae family that is popularly known in the south of Tunisia because of its wide application in herbal medicine, including the use of its leaves to treat many diseases such as diarrhea, rheumatism, and intestinal disorders. The aim of this study was to evaluate the ulceroprotective and antioxidant activity of essential oil extracted from the leaves of J. phoenicea (EOJp) against hydrogen chloride (HCl)/ethanol-induced ulcers in rats. The antiulcer activities of 50, 75 and 100 mg/kg body weight (b.w.) EOJp were investigated on 0.3 M HCl/ethanol-induced ulcers in rats. The essential oil yield was 0.69% with 48 compounds; α-pinene was the principal component (20.24%). In vivo pretreatment with EOJp given orally provided dose-dependent protection against HCl/ethanol-induced gastric ulcers in rats. Furthermore, pretreatment with EOJp significantly decreased malondialdehyde (MDA) content and increased the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx). The activity of the antiulcerogenic EOJp could be from synergistic antioxidant and anti-secretory effects. Oral use of EOJp has excellent preventive effects on induced gastric ulcers comparable to those of the proton pump inhibitor (PPI) omeprazole.