The red swamp crayfish(Procambarus clarkii)is a species from the northeast of Mexico and the central south of the United States(Louisiana),actually is the dominant macroinvertebrate in several countries.It was introdu...The red swamp crayfish(Procambarus clarkii)is a species from the northeast of Mexico and the central south of the United States(Louisiana),actually is the dominant macroinvertebrate in several countries.It was introduced to several countries,generally for gastronomic reasons or to repopulate destroyed areas by a disease.While the first introduction of this species into the world is well-documented,little is known about its pathways of invasion and the reason for its rapid spread in several countries.P.clarkii is an aggressive crustacean that multiplies very fast and adapts to features of the invaded location.Adults of the species can disperse up to 1.6 km on land.Also,they dig deep holes which allows them to establish easily in wetlands and adjacent waterbodies that are hydrologically disconnected.This study takes place in the Gharb area(northwestern of Morocco)where several carcasses of P.clarkii have been found in different places.In the present study,it is a question of understanding how this species was introduced in this area,to establish a map of propagation of the species,and to evaluate the damage that it would have caused in the rice growing of Gharb.In Morocco,it was first sighted in the Gharb area in 2008 in the commune of Sidi Allal Tazi.Following this discovery,possible ways of the species introduction and the dispersal modes were explored that P.clarkii could use to invade the Gharb area.The results of this study can be used by natural resource managers,rice farmers,fishermen and the local population,to help them to locate the spread of P.clarkii,to identify vectors that move P.clarkii across political boundaries and illustrate the importance of limiting and prohibiting the movement of this invasive species across boundaries or into new ecosystems.展开更多
The determination and monitoring of aquifer formations on the eastern border of Moroccan Gharb basin are very difficult because of their spatial and temporal variation. To delimit these formations, a geophysical surve...The determination and monitoring of aquifer formations on the eastern border of Moroccan Gharb basin are very difficult because of their spatial and temporal variation. To delimit these formations, a geophysical survey of 52 geoelectric soundings was performed with a mesh of 500 m and electrodes distance between 1000 m and 3000 m. Geoelectric sections and resistivity maps show a horst and graben structure. The correlation of existing oil drillings shows that the Jurassic and Neogene formations are both affected by normal faults causing Jurassic deposits collapse with local thickening of the Miocene deposits, and reverse faults delimiting tectonic slices due to tension caused by prerifaine nappe advance. This fact confirms the generated structure by the resistivity method. The isobath map of resistant formations's roof show average depths extending from 400 to 800 m for calcareous sandstone that are potential aquifers while oil drillings indicate over 1000 m depths.展开更多
文摘The red swamp crayfish(Procambarus clarkii)is a species from the northeast of Mexico and the central south of the United States(Louisiana),actually is the dominant macroinvertebrate in several countries.It was introduced to several countries,generally for gastronomic reasons or to repopulate destroyed areas by a disease.While the first introduction of this species into the world is well-documented,little is known about its pathways of invasion and the reason for its rapid spread in several countries.P.clarkii is an aggressive crustacean that multiplies very fast and adapts to features of the invaded location.Adults of the species can disperse up to 1.6 km on land.Also,they dig deep holes which allows them to establish easily in wetlands and adjacent waterbodies that are hydrologically disconnected.This study takes place in the Gharb area(northwestern of Morocco)where several carcasses of P.clarkii have been found in different places.In the present study,it is a question of understanding how this species was introduced in this area,to establish a map of propagation of the species,and to evaluate the damage that it would have caused in the rice growing of Gharb.In Morocco,it was first sighted in the Gharb area in 2008 in the commune of Sidi Allal Tazi.Following this discovery,possible ways of the species introduction and the dispersal modes were explored that P.clarkii could use to invade the Gharb area.The results of this study can be used by natural resource managers,rice farmers,fishermen and the local population,to help them to locate the spread of P.clarkii,to identify vectors that move P.clarkii across political boundaries and illustrate the importance of limiting and prohibiting the movement of this invasive species across boundaries or into new ecosystems.
文摘The determination and monitoring of aquifer formations on the eastern border of Moroccan Gharb basin are very difficult because of their spatial and temporal variation. To delimit these formations, a geophysical survey of 52 geoelectric soundings was performed with a mesh of 500 m and electrodes distance between 1000 m and 3000 m. Geoelectric sections and resistivity maps show a horst and graben structure. The correlation of existing oil drillings shows that the Jurassic and Neogene formations are both affected by normal faults causing Jurassic deposits collapse with local thickening of the Miocene deposits, and reverse faults delimiting tectonic slices due to tension caused by prerifaine nappe advance. This fact confirms the generated structure by the resistivity method. The isobath map of resistant formations's roof show average depths extending from 400 to 800 m for calcareous sandstone that are potential aquifers while oil drillings indicate over 1000 m depths.
