Gyraulus marocana sp. nov., a new freshwater snail species (Mollusca, Gastropoda, Planorbidae) from Morocco

A new planorbid gastropod species is described: Gyraulus marocana sp. nov. It can be distinguished from other known species by its regularly striated ivory shell, with four whorls separated by a deep suture, prostate gland with 20 diverticula, phallotheca twice as long as the preputium and its orange stylet. The new species was found in the northern part of Morocco, in Lake Zerrouka, a Protected Area, being also a site of ecological and biological interest (known as SIBE). It is located in the Middle Atlas massif, which is a geographical barrier known for its other endemic molluscs.

Geopolymer Materials Based on Natural Pozzolans from the Moroccan Middle Atlas

The pozzolans of the Moroccan Middle Atlas are derived from a low explosive volcanism, mostly strombolian. They are mainly composed of olivine and pyroxene, presenting a less homogeneous structure (irregular vesicles). The main target of this project is to study the use of natural pozzolans (NP) and metakaolin as precursors for the production of geopolymeric binders. The characterization of raw materials and elaborated geopolymers was carried out to study their mineralogical, chemical, microstructural, and mechanical properties. The studied pozzolans and kaolin were crushed, grinded, and sifted to get a fine grain size diameter of less than 100 µm. Then, they were calcined at 750 °C for 2 h to achieve an amorphous structure, increasing of their reactivity. Geopolymer production consists of mixing pozzolans and metakaolin with different amounts with an alkaline solution of sodium hydroxide and sodium silicates. The mass proportion of metakaolin (MK) used in this study was 10%, 20%, and 30%. In the present work, the amount of metakaolin was added as a source of alumina. The elaborated geopolymers were characterized using XRD, FTIR, TGA, and SEM analyses. The compressive strength was measured at 7, 14, and 28 days. The results showed interesting mechanical proprieties at about 18 MPa at 28 days with the mixture containing 20% MK. The addition of MK showed a significant increase in mechanical properties of the elaborated geopolymer. Meanwhile, the other results confirmed the training of new phases in addition to N-A-S-H gel. All these results indicate that the use of pozzolans in the production of geopolymers could be a great solution for the sustainable management of this mineral resource.

Estimation des réserves en eau souterraine régulatrices dans la partie moyen-atlasique du fleuve Sebou (Maroc)

L'estimation de la ressource en eau souterraine dans le Moyen-Atlas est investiguée à partir des débits mesurés dans l'oued Sebou à la station d'Azzaba, sur la période 1959–2015. Pour cela presqu'une centaine de phases de tarissement a été individualisé pour construire des courbes maîtresses de tarissement à partir desquelles le calcul des volumes des nappes est possible. Il est calculé mensuellement à partir du débit modal dont nous posons l'hypothèse qu'il représente la limite entre ruissellement et alimentation uniquement par les nappes. Les calculs donnent un volume de la réserve régulatrice moyen de 54 hm3, mais extrêmement variable à l'échelle interannuelle et intra-annuelle. Ces résultats démontrent la faible inertie des aquifères du Moyen Atlas et soulignent la vulnérabilité du secteur agricole vis-à-vis de cette ressource même lors de courte période de sécheresse. The estimate of the groundwater resource in the Middle Atlas is investigated from the runoff measured in the Sebou wadi at the Azzaba station, over the period 1959–2015. Almost a hundred recession curves have been individualized to build the master recession curves from which the calculation of the volumes of groundwater is possible. It was calculated at a monthly scale from the modal flow, which we assume is the limit between runoff and flow supply only by the aquifers. The results indicated a volume of the average regulatory reserve of 54 hm3, but extremely variable on an inter-annual and intra-annual scale. These results demonstrate the low inertia of the Middle Atlas aquifers and underline the vulnerability of the agricultural sector to this resource even during short periods of drought.

How have sheep breeds differentiated from each other in Morocco? Genetic structure and geographical distribution patterns

Background Based on the relatively homogeneous origin of the sheep breeds in Morocco that originate mainly from Iberia, it is highly relevant to address the question of how these very diverse sheep populations differentiated from each other. The Mountains of the High Atlas and Middle Atlas are expected to constitute North–South and West–East geographical barriers, respectively, which could have shaped the history of the differentiation of sheep breeds. The aim of this study was to test this hypothesis by considering the genetic structure and the spatial distribution of five major breeds (Sardi, Timahdite, Beni Guil, Boujaad and D’man) and one minor breed (Blanche de Montagne), by analysing the mtDNA control region, using 30 individuals per breed. Results Phylogenetic and network analyses did not indicate any clear separation among the studied breeds and discriminant component principal analysis showed some overlap between them, which indicates a common genetic background. The calculated pairwise FST values and Nei’s genetic distances revealed that most breeds showed a moderate genetic differentiation. The lowest and highest degrees of differentiation were retrieved in the Beni Guil and Boujaad breeds, respectively. Analysis of molecular variance (AMOVA) indicated that more than 95% of the genetic diversity occurs within individuals, while between- and within-population variabilities represent only 1.332% and 2.881%, respectively. Isolation-by-distance, spatial Principal Component Analysis (sPCA), and spatial AMOVA analyses evidenced clear examples of geographical structuration among the breeds, both between and within breeds. However, several enigmatic relationships remain, which suggest the occurrence of complex events leading to breed differentiation. Conclusions The approaches used here resulted in a convergent view on the hypothetic events that could have led to the progressive differentiation between the Moroccan breeds. The major split seems to be linked to the West–East barrier of the Middle Atlas, whereas the influence of the High Atlas is less obvious and incompletely resolved. The study of additional breeds that have settled near the High Atlas should clarify the relationships between the breeds of the West part of the country, in spite of their small population size.

Effects of the Variety and Content of Natural Pozzolan Coarse Aggregate on the Thermo-Mechanical Properties of Concrete

The present study investigated the effects of the variety and content of three natural pozzolan coarse aggregates on concrete. Natural pozzolan aggregates have been obtained from three volcanoes (Boutagrouine, Timahdite, and Jbel Hebri) located in the Middle Atlas region in Morocco. The three pozzolans studied were characterized, and then a comparison was made by replacing the natural aggregate with the pozzolan aggregate in the concrete in different percentages, namely 25, 50, and 100 % in volume. The results showed that the variety and content of pozzolan aggregate have a significant impact on the properties of concrete, primarily caused by the characterization of pozzolan aggregate. The density of concrete decreases with the addition of pozzolan aggregate, which decreases depending on the type of pozzolan aggregate used. The highest compressive strength was measured in the concrete specimens prepared with aggregate BP while the lowest compressive strength was noted in the concrete specimens prepared with aggregate RP. On the other hand, the substitution of NA at 100% by BP, GP, and RP aggregates leads to a decrease in the thermal conductivity of about 67%, 62%, and 55% respectively.

On the Use of Tri-Stereo Pleiades Images for the Morphometric Measurement of Dolines in the Basaltic Plateau of Azrou (Middle Atlas, Morocco)

Hundreds of large and deep collapse dolines dot the surface of the Quaternary basaltic plateau of Azrou, in the Middle Atlas of Morocco. In the absence of detailed topographic maps, the morphometric study of such a large number of features requires the use of remote sensing techniques. We present the processing, extraction, and validation of depth measurements of 89 dolines using tri-stereo Pleiades images acquired in 2018–2019 (the European Space Agency (ESA) © CNES 2018, distributed by Airbus DS). Satellite image-derived DEMs were field-verified using traditional mapping techniques, which showed a very good agreement between field and remote sensing measures. The high resolution of these tri-stereo images allowed to automatically generate accurate morphometric datasets not only regarding the planimetric parameters of the dolines (diameters, contours, orientation of long axes), but also for what concerns their depth and altimetric profiles. Our study demonstrates the potential of using these types of images on rugged morphologies and for the measurement of steep depressions, where traditional remote sensing techniques may be hindered by shadow zones and blind portions. Tri-stereo images might also be suitable for the measurement of deep and steep depressions (skylights and collapses) on Martian and Lunar lava flows, suitable targets for future planetary cave exploration.