The importance of retention processes in upwelling areas for recruitment of Octopus vulgaris: the example of the Arguin Bank (Mauritania)

The relationship between recruitment of octopus ( Octopus vulgaris ) populations and environmental conditions off the Arguin Bank (Mauritania) in the main nursery ground was investigated between 1990 and 1996. Three environmental indices (coastal upwelling intensity, coastal retention and wind-induced turbulence indices) are derived from satellite infrared imagery (METEOSAT) and from the COADS (Comprehensive Ocean–Atmosphere Data Set) data to quantify the coastal retention process and productivity, both believed to be important factors for recruitment success. The octopus recruitment index as well as environmental indices fluctuate annually and seasonally. Linear regression and generalized additive models (GAM) are used to relate recruitment indices and the environmental conditions prevailing during the early-life planktonic stage, known to be the main critical period of the octopus life cycle. Coastal retention especially appears to be a key factor for recruitment success. Owing to seasonal variations in enrichment and mixing processes, larvae benefit from retention in the spring but are negatively affected by a breakdown in retention in the autumn. Increasing upwelling intensity is beneficial for octopus recruitment, as the Arguin Bank limits the detrimental dispersive effects linked to upwelling.     

Do Sardinella aurita spawning seasons match local retention patterns in the Senegalese–Mauritanian upwelling region?

Sardinella aurita is the most abundant small pelagic fish in the Senegalese–Mauritanian region. The success of its reproduction crucially depends on the local circulation as this determines whether larvae reach coastal nursery areas favorable to their survival or are dispersed into the open ocean. As a first step towards evaluating sardinella vulnerability to climate‐driven hydrodynamical changes, this study aims at underpinning how transport pathways drive optimal spatial and seasonal patterns for sardinella reproduction. We have used two estimates of the Senegalese–Mauritanian coastal seasonal circulation simulated by two hydrodynamical model configurations that differ in their forcing and topography. Nursery areas are determined by evaluating coastal retention with a Lagrangian individual‐based model that accounts for processes such as diel vertical migration and mortality as a result of lethal temperature exposure. Our results suggest that the shelf zones located at the Arguin Bank (19.5°N–21°N) and south of Senegal (12°N–14.75°N) are highly retentive. We find maximum retention rates in July–August and November–December over the Arguin Bank; from February–July and November–December over the southern Senegalese shelf; and lower retention rates over the central region (14.75°N–19.5°N) that are locally maximum in June–July when the upwelling weakens. These retention areas and their seasonality are in agreement with previously reported spawning patterns, suggesting that the Sardinella aurita spawning strategy may result from a trade‐off between retention patterns associated with the seasonal circulation and food availability. Exposure to lethal temperatures, although not well studied, could be a further limiting factor for spawning. The Lagrangian analysis reveals important connectivity between sub‐regions within and south of the system and hence underlines the importance for joint management of the Sardinella aurita stock.     

Risk behaviours for milk-borne diseases transmission along the milk chain in The Gambia and Senegal

The objective of this study was the characterisation of the traditional milk chain in Western Region (The Gambia) and Kolda (Southern Senegal); and the analysis of milk chain actors' risk behaviours for milk-borne diseases transmission. For this purpose, cattle herds involved in milk production, milk collectors, milk vendors and small-scale milk processing units were surveyed in the two study sites. A similar general milk chain organisation was found in the two sites with some particularities in farm management, compliance with hygienic measures at different levels, treatment of milk and milk consumption patterns. This results in a variable degree of risk of consumers' exposure to milk-borne diseases. Although the quality of the milk has been improved with the development of small-scale milk processing units, serious efforts are still needed with respect to pasteurisation procedure and to change the mindset of consumers who prefer in their majority drinking raw milk, fresh or soured, without any prior treatment.     

Spermiogenesis and spermatozoon of the liver fluke Mediogonimus jourdanei (Microphalloidea: Prosthogonimidae), a parasite of Myodes glareolus (Rodentia: Cricetidae)

Spermatological characters of the liver fluke Mediogonimus jourdanei Mas-Coma et Rocamora, 1978 were studied by means of transmission and scanning electron microscopy. Spermiogenesis begins with the formation of the differentiation zone containing two centrioles associated with striated rootlets and an intercentriolar body. These two centrioles originate two free flagella that undergo a 90 degrees rotation before fusing with the median cytoplasmic process. Both nuclear and mitochondrial migrations toward the median cytoplasmic process occur before the proximodistal fusion of flagella. Finally, the constriction of the ring of arched membranes gives rise to the young spermatozoon. The mature sperm of M. jourdanei measures about 260 microm and presents two axonemes of different lengths with the typical pattern of the Trepaxonemata, two bundles of parallel cortical microtubules, one mitochondrion, a nucleus and granules of glycogen. An analysis of all the microphalloidean species studied to date emphasised some differences in certain characters found in Maritrema linguilla J?gerski?ld, 1908 and Ganeo tigrinum Mehra et Negi, 1928 in comparison to those in the remaining microphalloideans. The presence and variability of such ultrastructural characters according to family, superfamily or order have led several authors to propose their use in the analysis of trematode relationships and phylogeny. Therefore, apart from producing new data on the family Prosthogonimidae, the present study also compares the spermatological organization of M jourdanei with other available ultrastructural studies focusing on the Microphalloidea.     

Electrophoretic patterns of acid soluble proteins and active isoforms of peroxidase and polyphenoloxidase typifying calli and somatic embryos of two reputed date palm cultivars in Morocco

Summary When subjected to micropropagation by tissue culture, the two reputed cultivars of date palm (Phoenix dactylifera L.); Bou-Sthammi noire, resistant to Bayoud disease and Bou-Feggous, of high fruit quality, give rise to three types of calli, called white and root-forming callus, hyperhydric and degenerating callus and friable and embryogenic callus. All explant sources, calli and germinated embryos were analysed by denaturing polyacrylamide gel electrophoresis (SDS-PAGE) for acid soluble protein composition. Phenol-oxidizing enzymes; peroxidase and polyphenoloxidase, were also, evaluated and the isoforms separated by polyacrylamide gel electrophoresis. When compared with the explant and germinated embryos, embryogenic calli of the two date palm cultivars could be identified by a concentrated polypeptide of molecular weight 27 500 and polypeptides of molecular weights 70 000 and 11 500. Hyperhydric and degenerating callus contained the polypeptide exhibiting the molecular weight 32 000. Embryogenic calli showed high levels of soluble, ionically and covalently bound peroxidases. The soluble acidic isoperoxidase of R _f 0.60, revealed in these calli and germinated embryos could be a marker of the two tissues. White and root-forming calli of Bou-Feggous cultivar were typified by soluble acidic isoperoxidases with high mobility (R _f 0.75) and anodic ionically wall-bound polyphenoloxidases similar to those of the explant sources. Polyphemoloxidase activities detected in calli and embryos were very low when compared with those of explants. Used as an early test to screen embryogenic calli of date palm, acid soluble proteins, peroxidase and polyphenoloxidase data could lead to introduce lightening and economy in the tissue culture technique.     

Effect of gamma-irradiation combined with washing and waxing treatment on physicochemical properties,vitamin C,and organoleptic quality of Citrus clementina Hort. Ex. Tanaka

To enhance the shelf life of a late variety of Moroccan Citrus clementina (Nour), ionizing treatments were applied at 0.3 kGy, as well as washing (cold water) and waxing treatments. It has been found that, despite the irradiation treatment, the washing and waxing treatment do not improve the quality of C. clementina, but rather result in yellower peels, peel injury, and reductions of vitamin C content, acidity, and soluble solids. However, gamma-irradiation alone enhanced significantly (p 相似文献   

Helminths of sheep and goats in desert areas of south-west Mauritania (Trarza)

Faecal samples were obtained from sheep and goats before, during and after the rainy season at three locations in south-west Mauritania. Several animals were also necropsied at the same time.Haemonchus contortus was the most prevalent worm. Infection by digestive-tract strongyles andStrongyloides papillosus was always very light (prevalence less than 20%). Sheep were more heavily infected than goats but animals under 1 year of age were not infected by digestive-tract strongyles. It is likely that young small ruminants became infected during the rainy season and that the parasites so acquired are inhibited in their development and/or survive nearly one year as adults.     

Spermiogenesis and ultrastructure of the spermatozoon of the trypanorhynch cestode Aporhynchus menezesi (Aporhynchidae), a parasite of the velvet belly lanternshark Etmopterus spinax (Elasmobranchii: Etmopteridae)

Spermiogenesis and the ultrastructural organisation of the spermatozoon of the trypanorhynch cestode Aporhynchus menezesi Noever, Caira, Kuchta et Desjardins, 2010 are described by means of transmission electron microscopy. Type I spermiogenesis of A. menezesi starts with the formation of a differentiation zone containing two centrioles separated by an intercentriolar body constituted by five electron-dense plates. Each centriole gives rise to a free flagellum, which grows at an angle of 90 degrees in relation to a median cytoplasmic process. The nucleus and cortical microtubules elongate along the spermatid body. Later, both flagella rotate and fuse with the median cytoplasmic process. At the final stage of spermiogenesis, the young spermatozoon is detached from the residual cytoplasm by a narrowing of the ring of arched membranes. The mature spermatozoon is a long and filiform cell, tapered at both ends, lacking mitochondria. It is characterized by the presence of two axonemes of the 9+'1' trepaxonematan pattern, the absence of crested bodies, the presence of parallel cortical microtubules and nucleus. This pattern corresponds to the type I spermatozoon of the eucestodes. The anterior extremity of the spermatozoon is characterized by the presence of an arc-like row of up to seven parallel cortical microtubules that partially surrounds the first axoneme. These anterior cortical microtubules are thicker than the posterior microtubules and, consequently, the sperm cell of A. menezesi exhibits two types of cortical microtubules. Another interesting aspect is the presence of alpha-glycogen rosettes. This spermatological pattern is similar to that observed in the spathebothriidean and diphyllobothriidean cestodes.     

Improvement of a Gravity Oil Separator Using a Designed Experiment

Several authors have pointed out the need to improve the design procedure of conventional oil-water separator. In this work, a batch test and various continuous runs based on a Plackett-Burman statistical plan were performed, in order to optimize a small (10 L/min) gravity oil-water separator technology intended to pre-treat wastewaters from vehicle service facilities. The results from the tracer tests realized did not show a coherent relationship between the performance of the separator (E) and the mixing regime qualified by means of the variable ε (ratio between the actual and nominal mean residence times). The statistical analysis showed that the oil removal efficiency variations (69-82%) were mainly dictated by the way the separator is configured. A two-step design procedure alternative of small gravity separators was suggested.     

Allometric models for aboveground biomass in dry savanna trees of the Sudan and Sudan–Guinean ecosystems of Southern Senegal

This paper presents new allometric models for woody savanna of the dry Sudanian zone of the southern part of Senegal and contributes to the needs for accurate and precise carbon estimates through improved statistical models and methods. The results are based on statistical relationships between the total dry biomass and either tree diameter at breast height (DBH) or tree height for a set of 101 individuals of different sizes from 13 dominant species in 6 protected forests. The statistical regression (cubic order 3) generated for DBH (5–41.5 cm) and tree height (2.5–15.6 m) showed significant R ² of 0.934 and 0.813, respectively. Using the same database, species-based models for the most represented genera (Acacia sp., Combretum sp. and Terminalia sp.) show more precision than the generic model. The model residual standard error and relative errors showed a good fit between observed and predicted data. Species-based models showed smaller errors compare to generic models outputs.