Typologie des eaux de surface du bassin du Sebou par multi-approche : corrélation entre indice biologique global des réseaux de contrôle et de surveillance (IBG-RCS) et l’approche physicochimique et microbiologique

L’étude consiste en l’utilisation de la démarche biologique, particulièrement les indices IBGN et IBG-RCS, pour montrer l’évolution de la qualité biologique des eaux de surface du bassin du Sebou dans la période 2009-2011. La caractérisation physicochimique/microbiologique de la qualité des eaux de surface et la caractérisation biologique moyennant l’indice biocénotique IBG-RCS de l’an 2011ont fait l’objet d’un traitement statistique. Les résultats obtenus montrent une certaine amélioration dans la qualité des eaux de surface du bassin d’étude. L’analyse statistique a montré la formation de deux groupes corrélés négativement, le premier composé de l’oxygène dissous et l’indice IBG-RCS alors que le deuxième est formé des paramètres révélateurs de pollution organique (DBO5, DCO, NH4+, Phosphate Total PT et coliformes fécaux : CF).Mots-clés : Bassin Hydraulique du Sebou, indice IBG-RCS, qualité - biologique, macro-invertébrés, qualité physicochimique.Sebou’s water surface multi-approaches typology: correlation between the global biological index of control and surveillance networks (IBG-RCS) and the physicochemical/microbiological approachThe study consists of using the biological approach, especially the IBGN and the IBG-RCS indexes, to show the evolution of the biological surface waters quality of the Sebou basin in the period of 2009-2011. The physicochemical/microbiological surface waters quality characterization and the biological characterization (IBG-RCS index) of the year 2011 were the subject of a statistical processing. The results showed some improvement in surface waters quality. The statistical analysis showed the formation of two negatively correlated groups, the first consisting of dissolved oxygen and the IBG-RCS index while the second consists of the parameters indicative of pollution (BOD5, COD, NH4+, PT and CF).Keywords : hydraulic basin of Sebou, IBG-RCS index, biological quality, macroinvertebrates, physicochimical quality

Geomorphology and geomorphological heritage of the Ifrane-Azrou region (Middle Atlas, Morocco)

Geomorphological heritage is a widely used term in European and North-American countries, but is still scarcely mentioned in Africa. Nevertheless, the attractiveness of the African countries is often intimately connected to its breathtaking and endless geological landscapes. Morocco is one of those countries that has the widest diversity in landscapes and landforms, ranging from the Mediterranean and Atlantic coasts over the Rif, Middle Atlas, High Atlas and Anti-Atlas mountain chains to the great rocky and sandy deserts in the South. A wide variety of geological units hosting different types of important economic mineral deposits cover a temporal range from Late Precambrian to Quaternary. A detailed geomorphological study has been carried out in the region of Ifrane and Azrou (Middle Atlas, Central Morocco) using a combination of high resolution satellite data and direct field observations integrated by geological maps and scientific literature. In order to describe and evaluate the geomorphological heritage of this area, 40 geomorphosites have been selected comprising springs, karst landforms (polje, dolines, caves, sinkholes, stone forests, cryptokarstic dolines), carbonate depositional landforms (travertines and waterfalls), fluvial landforms (meanders, canyons, palaeo-valleys, etc.), structural landforms (triangular facets, hogbacks, cuestas, residual outcrops, etc.) and volcanic landforms (volcanoes, caldeira, pyroclastic cones, lava tube). The results of this research have been summarised in a thematic map, representing the geomorphosites related to various landscape units. © Springer-Verlag 200

A Review of Freshwater Crayfish Introductions in Africa

This review summarizes and analyses information on freshwater crayfish introductions in Africa. A total of 136 research papers and reports were found to be relevant. Forty-eight percent reported presence; 21% described negative impacts; 11% referred to potential socio-economic benefits; 9% evaluated control measures; 6% documented co-introduced parasites. Out of nine introduced crayfish species, five species Astacus astacus, Cherax quadricarinatus, Faxonius limosus, Procambarus clarkii, and Procambarus virginalis have established populations in the wild. Astacus astacus and F. limosus are present only in Morocco and P. virginalis is limited to Madagascar. Cherax quadricarinatus and P. clarkii have established populations in five and six countries, respectively. The main driver of crayfish introductions was to provide socio-economic benefits through aquaculture and fisheries development but there is limited evidence of success. Prevailing negative socio-economic impacts are linked to damage to agricultural water infrastructure, damage to fishing gear and declining fisheries performance. Ecological impacts pertain to direct and multi-trophic consumptive effects as well as indirect competitive effects primarily upon macro-invertebrates and potential spillover of parasites to other decapods. Research priorities are determining abundance, distribution and spread of crayfishes and assessing ecological impact to inform management decisions