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Correspondance i cet auteur Influence du substrat sur la rkpartition des Crustacks stygobies interstitiels du Haut-Atlas occidentalThe influence of sediment granulometry in the distribution of the interstitial stygobikey words: hyporheon, grain size frequency, amphipods, isopods ontic crustaceans in the western High Atlas. AbstractThe interstitial stygobiont distributions of two rivers in the western High Atlas is analyzed in relation with sediment granulometry. Sixteen stations were sampled along the rivers N'Fis and Zat and their tributaries. Granulometry analyses were performed. Three grain size sediment types constitute the subterranean biotopes and reflect the local hydrodynamical conditions. The main rivers stations, which undergo frequent natural or human disturbances, are characterized by a high content of tine sediment; in contrast, tributaries stations show coarse and well-classified sediments due to more stable biotopes and more regular hydrological conditions. The 92 taxa group 28 stygobiontic species with I I crustaceans species. PCA, based on 16 stations, three faunistic richness indexes and three granulometric factors display a high correlation between coarse grain-size content and the richness of stygobiontic taxa. A high silt content both limits the interstitial taxa and excludes crustaceans that occur only in coarse gravels. The granulometric preferenda in the species of the amphipod genus Metucrangoriy and isopods Microcerbrrus. Microcharon and Typhlocirofuna are shown on SHEPARD triangular diagrams. Cohabitation of several species of the same genus could be explained by the occupancy of different ecological niches resulting from the grain-size proportion.F. DE BOVEE et (11.

On the basis of extensive surveys, an update is provided on the diversity, taxonomy, anatomy, and geographic distributionof five species of North African freshwater planarians, including the description of one new species. The new species Dug-esia tubqalis Harrath & Sluys, sp. nov. is mainly characterized by the following features: an elongated penis surroundedwith two penial folds at its base, the dorsal one bigger than the ventral ; an atrium divided into a male and common atriumby a kind of non-muscular ridge; a terminal expansion of the ejaculatory duct just before it opens at the tip of the penispapilla. The record of Dugesia sicula represents the first fully documented record of a naturally sexual, diploid (2n=18)population in North Africa. The first finding of Polycelis nigra on the African continent is documented. The genus Polyce-lis is recorded here with two species, Polycelis nigra and Polycelis felina. We also noted the presence of Schmidtea polychroa, which is widespread in Europe and introduced in North America.

In the north of Marrakesh (Morocco), the high anthropogenic activity and the permeable nature of the geological ground makes the water of Jbilet vulnerable to contamination. The results of physico-chemical analyses conducted in 2006 showed that two groups of wells could be distinguished. Groundwater of wells located on the right bank of the Tensift River, which are far from any source of pollution, is of fairly good quality, well oxygenated, at neutral pH and with rather weak levels of organic compounds. In contrast, in the other wells in the area of the landfill of the city of Marrakesh and those in the peri-urban area demonstrate deteriorated water quality. The nutriment and organic matter content is quite high. Results of bacteriological analyses of water showed a fairly high faecal contamination. In this area the soil is highly permeable and promotes infiltration of organic pollutants and minerals as well as of pathogen and opportunistic bacteria into groundwater. After their penetration, these microorganisms form films around grain particles. The movements of the stygofauna in the interstices allow bacteria to settle on their exoskeleton and seep into their gut, thus being a potential source of groundwater contamination. An analysis of bacterial flora showed that the rate of bacteria is high in the digestive tract of two crustacean species of the stygobites Typhlocirolana haouzensis and Metacrangonyx spinicaudatus, and that it depends on the species and the bacteria. Bacteria may be one of the potential nutritional resources for stygobites.

Olive Oil Waste Water (OOWW) is acidic water known for its antibacterial and phytotoxic effects. In Morocco, these effluents are generally drained into the surrounding environment without any treatment or are collected and retained in large evaporation basins, which can constitute a source of potential pollution of groundwater. The analysis of water from 14 wells, in an agricultural zone, where there are four storage basins of OOWW coming from various types of oil mills, showed that their physicochemical and biological quality is largely influenced by the presence of these basins. Indeed, high values of COD (400 mg O2 L(-1)), polyphenols (180 mg l(-1)) and electrical conductivity (1.89 mS cm-') were recorded in P5 water. This well is located only 5 m from a storage basin of OOWW coming from the H4 oil mill which rejects OOWW charged with organic matter (more than 290 g of O2 L(-1) of COD, on average). However, the settlement of a basin, dug close to a modern oil mill (H3), which produces large OOWW volumes but is loaded with low organic pollutant concentration (100 g of O2L(-1) of COD), reduced notably the effect of the OOWW infiltration on groundwater. This resulted in the improvement of the groundwater physicochemical quality near this basin (P7 and P8); the organic matter contents expressed by COD vary from 26.7 mg l(-1) to 30 mg l(-1) and the polyphenol contents are on average between 41 mg l(-1) and 47.6 mg l(-1). The analysis of the total well water fauna showed a great taxonomic richness with variations in time and space. The biodiversity decreases in groundwater polluted by the oil mill waste and the underground fauna disappears completely if the degree of contamination of groundwater is high.