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Depending on the city and its socio-geographical context, urban and peri-urban agriculture presents different types of production systems. Considered as a way to alleviate poverty, this type of agriculture has gradually acquired certain legitimacy in urban projects. In a study carried out in Dakar, we investigated six categories of stakeholders - from the agricultural and policy-making sectors - to analyze their perception of this type of agriculture in areas like Niayes (interdune depressions which very favorable to agriculture), and to characterize the production systems. By adopting an innovative analytical approach, we were able to highlight the following: a typology of farms representing the diversity of production systems and household activities, an analysis of their location in four agricultural zones differentiated by urban proximity, the variability of the internal and external sustainability of farms, an analysis of multi-functionality of agriculture and agricultural areas based on the perception of the six categories of actors. These elements provide new insights into various stakeholders. However, in order to provide solutions for the various problems faced by this type of agriculture, we suggest scientific and technical solutions such as the creation of an agriculture observatory.

The stock of the Senegalese flat sardinella, Sardinella maderensis, is highly exploited in Senegal, West Africa. Its growth and reproduction parameters are key biological indicators for improving fisheries management. This study reviewed these parameters using landing data from small-scale fisheries in Senegal and literature information dated back more than 25 years. Age was estimated using length-frequency data to calculate growth parameters and assess the growth performance index. With global climate change there has been an increase in the average sea surface temperature along the Senegalese coast but the length-weight parameters, sex ratio, size at first sexual maturity, period of reproduction and condition factor of S. maderensis have not changed significantly. The above parameters of S. maderensis have hardly changed, despite high exploitation and fluctuations in environmental conditions that affect the early development phases of small pelagic fish in West Africa. This lack of plasticity of the species regarding of the biological parameters studied should be considered when planning relevant fishery management plans.

Abstract Increasingly frequent and severe bleaching events driven by climate change are decreasing coral populations worldwide. Recovery of these populations relies on reproduction by the survivors of such events including local and upstream larval sources. Yet, corals that survive bleaching may be impaired by sublethal effects that suppress reproduction, reducing larval input to reefs, and consequently impeding recovery. We investigated the impact of the 2020 mass-bleaching event on Acropora millepora reproduction on inshore, turbid reefs in Woppaburra sea Country (the Keppel Islands), to improve our understanding of the effects of bleaching on coral populations. A. millepora experienced high bleaching incidence but low mortality across the island group during this event and thus constituted an ideal population to investigate potential sublethal effects on reproductive output. Six months after the heat wave, and just prior to spawning, we collected, decalcified, and dissected samples from 94 tagged A. millepora colonies with a known 2020 bleaching response, to investigate the relationships between stress severity and reproduction. Despite having regained their pigmentation, we detected a significant reduction in fecundity in colonies that had bleached severely. Considering the impact of the bleaching event on the coral population sampled (i.e. mortality, bleaching severity and colony size), coupled with reductions in fecundity, we estimated a total decrease in population-level reproductive output of 21%. These results suggest that reduced reproductive output may impact recovery of coral populations following bleaching and should be considered alongside traditional estimates from coral mortality.

In this work, impacts of temperature and dust cleaning on photovoltaic module performance operating in sub-Saharan's climate are investigated. Two single junction technologies, monocrystalline and polycrystalline silicon, and one micromorph (amorphous/micrystalline) thin film silicon tandem technology are considered. We have recorded at the same time under real operating conditions, the module temperature and the current versus voltage characteristics of each module, and the local solar irradiation. All the measurements were performed with the outdoor monitoring and test facility located at Ouagadougou in Burkina Faso. The results show the drop of generated power of dusty modules for the same irradiation level. Between April and June (where temperatures are higher) a significant drop of output power is observed, despite a daily cleaning. Furthermore, performance losses are observed for all technologies compared to that under standard test conditions. However, the micromorph silicon tandem technology with low temperature sensitivity present the less losses in performance compared to the monocrystalline and the polycrystalline single junction modules, even if the modules are not cleaned.

Este estudio de modelado se lleva a cabo para examinar el impacto potencial de la ubicación de la reforestación (cinturón verde) (ya sea en el Sahel o en la región de Guinea) en el sistema climático de verano de África Occidental. Con este fin, se realizaron tres simulaciones utilizando el modelo climático regional RegCM4 impulsado por el reanálisis de ERA-Interim a una resolución horizontal de 50 km en un dominio de África Occidental para el período 2000–2011. El primer experimento, a saber, el control (CTRL), utiliza la cubierta vegetal estándar, mientras que los otros dos incorporan a lo largo de la integración del modelo, una banda de reforestación zonal de hoja ancha perenne en diferentes ubicaciones: (i) sobre una latitud de banda de 13° N–17° N en una región del Sahel-Sahara (experimento en lo sucesivo denominado GB15N) y (ii) entre 8.5° N-11.5 ° N en la región de la costa de Guinea (experimento en lo sucesivo denominado GB10N). Una comparación del experimento CTRL con el observatorio revela una reproducción fiel del patrón de precipitación media boreal y estacional de verano, aunque siguen existiendo sesgos secos/húmedos sustanciales, especialmente en el Océano Atlántico. Además, el ciclo estacional en las subregiones coincide satisfactoriamente con el patrón observado. La reforestación GB15N conduce a un aumento de la precipitación en el rango de 2–4 mm/día sobre las áreas boscosas, mientras que en la reforestación GB10N, el aumento de la precipitación es más débil y no necesariamente se encuentra en las áreas boscosas. El enfriamiento de la temperatura se observa en el área reforestada y puede explicarse por una disminución del flujo de calor del suelo relacionado con una reducción del albedo superficial. Cette étude de modélisation est menée pour examiner l'impact potentiel de l'emplacement du reboisement (ceinture verte) (au Sahel ou dans la région guinéenne) sur le système climatique estival ouest-africain. À cette fin, trois simulations utilisant le modèle climatique régional RegCM4 piloté par une réanalyse intermédiaire ERA ont été effectuées à une résolution horizontale de 50 km sur un domaine ouest-africain pour la période 2000–2011. La première expérience, à savoir le contrôle (CTRL), utilise la couverture végétale standard, tandis que les deux autres incorporent tout au long de l'intégration du modèle, une bande de reboisement zonale de feuillus persistants sur différents emplacements : (i) sur une latitude de 13° N–17° N dans une région sahélo-saharienne (expérience ci-après dénommée GB15N) et (ii) entre 8,5° N-11,5 ° N dans la région de la côte guinéenne (expérience ci-après dénommée GB10N). Une comparaison de l'expérience CTRL avec l'observation révèle une reproduction fidèle du modèle de précipitations saisonnières moyennes boréales et estivales, bien que des biais secs/humides substantiels subsistent, en particulier dans l'océan Atlantique. De plus, le cycle saisonnier sur les sous-régions correspond de manière satisfaisante au modèle observé. Le reboisement GB15N entraîne une augmentation des précipitations de l'ordre de 2 à 4 mm/jour sur les zones forestières, alors que dans le reboisement GB10N, l'augmentation des précipitations est plus faible et pas nécessairement située dans les zones forestières. Le refroidissement thermique est observé sur la zone reboisée et peut s'expliquer par une diminution du flux de chaleur du sol liée à une réduction de l'albédo de surface. This modeling study is conducted to examine the potential impact of the reforestation (greenbelt) location (either in Sahel or in Guinean region) on West African summer climate system. To this end, three simulations using the regional climate model RegCM4 driven by ERA-Interim reanalysis were performed at 50 km horizontal resolution over a West African domain for the period 2000–2011. The first experiment, namely the control (CTRL), uses the standard vegetation cover, while the two others incorporate throughout the model integration, a zonal reforestation band of evergreen broadleaf over different locations: (i) over a 13° N–17° N band latitudes in a Sahel-Sahara region (experiment hereafter referred to as GB15N) and (ii) between 8.5° N–11.5° N in the Guinea Coast region (experiment hereafter referred to as GB10N). A comparison of the CTRL experiment with observation reveals a faithful reproduction of the mean boreal and summer seasonal precipitation pattern, though substantial dry/wet biases remain, especially in the Atlantic Ocean. In addition, the seasonal cycle over sub-regions matches satisfactory the observed pattern. The GB15N reforestation leads to a precipitation increase in the range of 2–4 mm/day over the forested areas, whereas in the GB10N reforestation, precipitation increase is weaker and not necessarily located in the forested areas. Temperature cooling is observed over the reforested area and may be explained by a decrease of ground heat flux related to a reduction of the surface albedo. يتم إجراء دراسة النمذجة هذه لدراسة التأثير المحتمل لموقع إعادة التحريج (الحزام الأخضر) (إما في منطقة الساحل أو في المنطقة الغينية) على نظام المناخ الصيفي في غرب إفريقيا. ولتحقيق هذه الغاية، تم إجراء ثلاث عمليات محاكاة باستخدام نموذج المناخ الإقليمي RegCM4 مدفوعاً بإعادة تحليل ERA - Interim بدقة أفقية 50 كم على نطاق غرب إفريقيا للفترة 2000–2011. تستخدم التجربة الأولى، وهي التحكم (CTRL)، الغطاء النباتي القياسي، بينما يدمج الآخران في جميع أنحاء تكامل النموذج، نطاق إعادة تشجير نطاقي من الأوراق العريضة دائمة الخضرة على مواقع مختلفة: (1) على خط عرض 13° N -17 ° N في منطقة الساحل والصحراء (يشار إلى التجربة فيما يلي باسم GB15N) و (2) بين 8.5° N-11.5 ° N في منطقة ساحل غينيا (يشار إلى التجربة فيما يلي باسم GB10N). تكشف مقارنة تجربة CTRL مع الملاحظة عن تكاثر مخلص لمتوسط نمط هطول الأمطار الشمالية والموسمية الصيفية، على الرغم من بقاء تحيزات جافة/رطبة كبيرة، خاصة في المحيط الأطلسي. بالإضافة إلى ذلك، فإن الدورة الموسمية على المناطق الفرعية تتطابق بشكل مرضٍ مع النمط المرصود. تؤدي إعادة التشجير GB15N إلى زيادة هطول الأمطار في حدود 2–4 مم/يوم على المناطق الحرجية، في حين أن زيادة هطول الأمطار في إعادة التشجير GB10N أضعف وليست بالضرورة موجودة في المناطق الحرجية. يتم ملاحظة تبريد درجة الحرارة فوق المنطقة المعاد تشجيرها ويمكن تفسيره بانخفاض تدفق الحرارة الأرضية المرتبط بانخفاض البياض السطحي.

Abstract Along the coast of North-West Africa, fish supply is important at both socio-economic and cultural levels while threatened by climatic changes. To assess the impact of climate change on the distribution of small pelagic fish, a comprehensive trend analysis was conducted using data from 2,363 trawl samplings and 170,000 km of acoustics sea surveys spanning the period 1995–2015. The approach included estimating eight northern small pelagic species' presence and acoustics spatial distribution of the sardinella. The analysis incorporated key environmental variables, including sea temperature, chlorophyll-a concentration, and a wind-based Ekman upwelling index. The Southern Canary Current Large Marine Ecosystem (CCLME) was divided into five distinct ecological areas, extending from Morocco to Senegal, providing a spatialized perspective on the dynamic changes unfolding within these characteristic areas. Then, yearly averages of the monthly data per area were calculated. Strong warming is reported in all five areas. Over 34 years, from 1988 to 2021, several discernible trends emerged, with the southern CCLME experiencing increases in both wind speed and upwelling intensity, particularly in areas where the coastal upwelling was already the strongest. Despite upwelling-induced cooling mechanisms, sea surface temperature increased in most areas, indicating the complex interplay of climatic-related stressors in shaping the marine ecosystem. Concomitant northward shifts in the distribution of sardinella and other species were attributed to long-term warming trends in sea surface temperature (SST). As a result, the abundance of Sardinella aurita, the most abundant species along the coast, has increased in the subtropics (north part) and fallen in the intertropical region (south part). Independent environmental and ecological observational time series confirm a northward shift of around 180 km in one decade for S. aurita, while S. maderensis did not move significantly. Spatial shifts in biomass from 30 to 145 kilometers were observed for six other exploited small pelagic species, similar to those recorded for surface isotherms. An intensification in upwelling intensity within the northern and central regions of the system is documented without change in marine primary productivity. In contrast, a stable upwelling intensity is reported in the southern region (Senegal), which is associated with a decline in primary productivity. These environmental differences were associated with several small pelagic species beyond national boundaries whose recent overexploitation adds a new threat to their sustainable future in the whole region. Such changes must motivate common regional policy considerations for food security and sovereignty in all West African countries sharing the same stocks.