Dissertations / Theses on the topic 'West African coastal zone'

The overarching aim of the work presented here is to contribute to the development of a new interdisciplinary approach to fisheries economics for fisheries governance. it is geographically limited to West Africa but results can be used in other areas where small scale fisheries are active and governance rules are not fully implemented. The disciplinary orientations and conceptual frameworks applied in the research are institutional analysis and governance, as well as the assessment of key drivers of change. The new institutional economic theory provided a sound conceptual frame to analyse fisheries as it brings together economics (theory of the firm and social cost theory), law (convention, contracts, etc.) and sociology (sanctions, taboos, customs, traditions, and codes of conduct). Used on its own it provides a good framework for the analysis of the fish chain and relationships between stakeholders (wealth distribution and equity) and the whole governance of fisheries, coastal zones and oceans. Combined with neo-classical tools such as modelling of fishing activities, it provides a good analytical method to predict effects of management measures on fisher strategies. Furthermore, coupled with an ecological model such as ECOPATH or ECOSIM, its gives a holistic modelling tool (integrating ecology, economic and social dimensions) for the assessment of the full costs and benefits (private and public) of fishing practices and policy policies. The research suggests that the key drivers of change are often hidden and therefore not taken into account while designing management measures. Among shaping drivers, research in West Africa shows that international trade and its rules is shaping the orientation and the functioning of small scale fisheries. Fisher migration, which is directly linked to the trade driving effects, is currently one of the major drivers of change of West African fisheries and the most destabilizing factor. The main results, such as the identification of drivers of change (e.g. international trade, migration), and the integration of social, economic and ecological models are currently used by international institutions such as FAO, UNEP, UNDP and the Group of the ACP countries, regional organisations such as ATLFALCO (Ministerial conference of the African Atlantic countries), the Sub-regional Fishery Commission of seven West African countries and at national level by fishery ministries. The future of fisheries governance in West Africa is strongly linked to a better understanding of small scale fisher strategies and the way they react to fishery management. New research activities on co-management have to be developed in order to switch from a strong centralised fishery management process to a local one where fisher communities play a significant role. Aside from this, work has to be continued to implement the integrated approach into the fishery governance system in West Africa and in other world coastal countries.

Inflation and output growth relationship is of interest to policymakers and researchers. In the West African Monetary Zone, the attainment of low inflation rate is considered as one of the convergence criteria for the successful implementation of monetary union in the zone. Although there has been empirical evidence that the relationship between inflation and output growth in the WAMZ is non-linear, the question yet to be answered is, “at what level is inflation detrimental to economic growth?” This paper extends the link of analysis by investigating the optimal inflation for the WAMZ countries using the quadratic approach to threshold estimation. The findings drawing from economic theory and analysis suggests that inflation rate in the WAMZ is significantly associated with lower growth only after it reaches 12.86 percent. The result further indicates that there are significant differences in the inflation threshold levels in the WAMZ countries. The findings of this research are not surprising given the institutional features and structure of the different countries in the zone. The findings of the research suggest that monetary authorities in the WAMZ countries could accommodate inflation rate up to the threshold level, even when that is higher than what is currently being targeted in the zone, so as not to stifle growth in the area. Also, although the WAMZ countries belong to the same geographical area, which could enhance group formation; there could be other sources of heterogeneity like different political, legal, economic, and national policies that drive individual growth processes in the zone.
Central Bank of Nigeria

There is ongoing global concern over unwanted regime shifts in marine systems. Shifts from diverse and productive algal-dominated ecosystems to less productive urchin and coralline-dominated temperate reefs are becoming increasingly common. Kelp forests found along South Africa's south-west coast between Cape Point and Cape Agulhas occur in a region of biogeographical overlap. They are commonly referred to as transition zone kelp forests and are dynamic ecosystems that are particularly susceptible to grazing influence from species such as sea urchins. This study (1) explores the uniformity of these transition zone kelp forests along the western side of False Bay, with a focus on macroalgae and urchins, (2) identifies a threshold in urchin density above which algal abundance declines and (3) seeks to identify relationships between attached and drift algal abundance. Twenty replicate quadrats were sampled in six kelp forests along the western side of False Bay. Within each quadrat, urchins (Parechinus angulosus) and kelps (Ecklonia maxima) were counted, percentage covers of various understorey algal species were recorded and drift algae were collected. Although there was significant variability in algal and urchin cover across the six sites, kelps generally increased from north to south, while urchins did the opposite. Urchins were negatively correlated with algal communities, and a localised threshold of 1.43kg/m² (50 urchins/m²) was identified, above which attached kelp density failed to increase above 10/m² and percentage cover of understorey algae usually remained below 20%. Surprisingly, no relationship was discovered between abundance of drift kelp and attached kelp, understorey algae or urchin density. This result was likely distorted by the naturally turbulent conditions of South African waters. Results highlight the complexity of these cool-water environments. To better understand the role of urchins in this system, experimental research into the feeding behaviour and effect of P. angulosus on kelps and understorey seaweeds in the presence/absence of drift algae is advised.

This research focuses on applying littoral vulnerability assessment (LVA) into the coastal management process of Barbados, W. I. using a multipurpose rapid assessment technique, making the most of limited data and process knowledge. The conceptual and theoretical components of coastal vulnerability assessment set the context on which the LVA process is built. Three environmental sensitivity indices (ESIs) have been developed to using to a selection of the variables to characterise the coastline. Seventy four coastal locations are described according to the following ESIs: - Wave Exposure Index, Coastal Sensitivity Index, and Beach Aesthetic Index. These respectively represent the coastline being 92% being sheltered 64% having a high to very high sensitivity to oil pollution and 51% being of good to very good aesthetic quality Factor and cluster analyses were used to develop Coastal Vulnerability and Degree of Risk Indices. Twenty three coastal segments were analysed of which 52% were considered to be high to very highly vulnerable to erosion and potential storm wave damage. The south coast's most vulnerable locations are Casuarina, Dover and St Lawrence while west coast locations are Fitts Village, Paynes Bay and Sandy Lane. The highest degrees of risk locations identified were Casuarina, St. Lawrence. Batts Rock. Dover and Carlisle Bay. The research has also interpreted case studies using GIS and available socio economic information to quantify property vulnerability based on potential economic loss value. These results show that 88% of the coast is fully urbanized, with 63% being used in tourism infrastructure and having the greatest land value. The thesis also includes the construction of LVA profile model, which is intended to: 1) contribute to the formulation of future coastal management policies in Barbados and 2) provide an easy to implement monitoring procedure for small islands embarking on coastal management initiatives. The research demonstrates the use of scientifically valid yet inexpensive methods of quantitative shoreline monitoring and assessment, which could be of practical value in the coastal management of Small Island Developing States.

The forest floor represents the uppermost organic and organicenriched mineral soil horizons. They have been formed by the deposition of organic material and the subsequent biologically mediated decomposition. The forest floor influences rooting-zone temperature, aeration, moisture, and nutrient conditions, and hence, forest productivity. Considering the importance of the forest floor, and the fact that it is exposed to disturbance (being the surface layer), we need to assess the potential impacts our logging practices may have. Clearcutting, one of the contentious silvicultural practices used in British Columbia, is imputed to most adversely affect ecosystems and sustainability. We assessed the long-term impact of clearcutting on the forest floor by documenting changes in the thickness, chemical and biotic properties of the humus form across a chronosequence of forest stands. The study was located in the largest and most representative portion of the coastal rainforest the Very Wet Maritime Coastal Western Hemlock (CWHvm) subzone.

The coastal zone of Belize is home to the largest recorded number of the threatened Antillean manatee (Trichechus manatus manatus) within the species' Caribbean range. The objectives of my study were: (1) to determine long-term trends in aerial survey counts and indices of the manatee population in the coastal zone of Belize; and (2) to examine the seasonal change in manatee distribution among habitats in the coastal zone. Standardized extended-area aerial surveys were conducted along the entire coastline of Belize in the dry and wet seasons of 1997, and 1999 - 2002. Manatees were counted in five habitat categories: cay, coast, estuary, lagoon, and river. Total sightings per survey ranged from 90 to 338; the greatest number was counted in the 2002 wet season. Calf percentage ranged from 5 to 13. A slight negative trend in total counts was significant for dry-season, not wet-season surveys, indicating an interactive effect of season and year. Based on analysis of variance, the Abundance Index (transformed manatee sightings per hour) did not differ significantly among years, although it varied significantly within year by season and habitat by season. In applying a spatial approach, the general survey route was buffered 1 km on both sides, and 1 km grids were overlaid and classified by habitat type. The presence or absence of each cell for each survey was used in likelihood ratio tests of the single and interactive effect of season and habitat. The Index for river habitat was higher in the dry season, while cay habitat was higher in the wet season. Overall, near-shore habitat (estuary, lagoon, and river) showed a higher Index than did the offshore habitat (cay and coast) although the total number of sightings was higher offshore. Considering the interactive effect of year, season, and habitat, long-term studies are needed, in both seasons, and among all habitats to account for variation. Continued broad-scale surveys, along with metapopulation analysis would fine-tune the understanding of specific sites, enhancing integrated coastal zone management for protected species and their habitat systems.

Le problème de la dégradation de l’environnement n’est plus aujourd’hui celui de la rédaction de nouvelles conventions, même si tous les domaines ne sont pas encore couverts par le droit, mais bel et bien celui de l’effectivité et de la mise en application des normes en vigueur. Le plus souvent le droit existe mais il est inappliqué ou mal appliqué. Ceci soulève deux difficultés : l’une relative à la mise en œuvre du droit et, l’autre portant sur le contrôle de sa bonne application. Dans ce contexte, le continent africain ne peut œuvrer à son unité et son développement économique sans se soucier du changement climatique notamment dû aux gaz à effet de serre et de la destruction du milieu marin. Par ailleurs, l’Organisation pour l’harmonisation en Afrique de droit des affaires (OHADA) doit permettre à l’Afrique de progresser et d’œuvrer à la responsabilisation des entreprises en matière de protection de l’environnement et du climat. Face à ce vide juridique, l’OHADA devrait s’intéresser dans un proche avenir à l’adoption d’un acte uniforme relatif à la Responsabilité sociale et environnementale. La mise en œuvre des politiques environnementales et du droit qui en résulte nécessite une véritable révolution culturelle. Ainsi, ce sont les jeunes générations qui doivent recevoir une éducation adaptée sur les nouveaux enjeux écologiques. Si les principes généraux du droit de l’environnement contribuent de manière importante au développement de la soft law en droit international, il est plus étonnant de constater que le phénomène prend une importance croissante en droit interne. Au-delà des aspects juridiques formels, la mise en œuvre des conventions régionales imposera de relever d’autres défis, au premier rang desquels figure le renforcement des capacités institutionnelles des autorités nationales à concilier les impératifs économiques, sociaux et environnementaux
The problem of environmental deterioration is not linked to the draft of new agreements anymore, even though not all fields are covered so far by the existing law, but to the efficiency of the norms in effect. Most often, law exists, but is badly applied or not applied at all. This leads to two problems: first, the implementation of law, and second, the control of its application. In this context, the African continent cannot achieve its unity and its economic development without caring of the sword of Damocles which is the global warming caused by greenhouse gases and environmental destruction. Furthermore, the OHADA (Organization for the Harmonization in Africa of Business Law) should allow Africa to significantly advance on the subject of the companies’ responsible behaviour in terms of environmental and climate protection. In order to fill this gap, the OHADA should adopt in the near future a Uniform Act concerning social and environmental responsibility. The implementation of environmental policies and the application of the norms arising from them require a cultural revolution. The young generations should receive an education which is adapted to the new ecological challenges. The principles contribute in an important way to the development of the soft law in international law, but it is even more surprising that this phenomenon is more and more important in national law. Beyond formal legal aspects, the implementation of regional agreements will be confronted to further challenges: first of all, the reinforcement of the national institutional authorities’ capacity to reconcile economic, social and environmental imperatives

A mass balance approach was used in an attempt to quantify nutrient flux to the nearshore at the West Coast, Barbados, W.I. Total nitrogen and total phosphorus levels of the groundwater at inland pumping stations and above beach margins, as well as in the water of the nearshore zone and approximately 2 km offshore, were obtained. Nearshore groundwater seepage rates and salinity data were also taken. This study attempted to use this raw data to estimate flushing rates, nutrient loading rates, and nutrient loss rates, to ultimately create a picture of the fate of nutrients as they travel in groundwater into the nearshore zone. Annual loading for the entire West Coast was calculated at 1.46 x 105 kg NO3---N for nitrogen and 1.19 x 103 kg PO4 3---P for phosphorus. Mean nutrient levels in groundwater above the beach margin were estimated at 969.83 muM for nitrogen and 3.63 muM for phosphorus. For nitrogen and phosphorus respectively, these levels were twice and three times higher than at the pumping stations farther inland; and there was also a fourfold and fivefold drop in nitrogen and phosphorus, respectively, in the nearshore zone relative to this groundwater above the beach margin. This indicated that the dense coastal population at the West Coast was adding significant amounts of nutrient to groundwater after it had left the inland pumping stations. There were no patterns of gradation in nutrient concentrations detected within the immediate nearshore, making completion of an accurate mass balance impossible, though indicating that there was significant advection of submarine groundwater offshore, beyond the study zone. This may contribute to the poor health of West Coast reefs, where sewage and fertiliser leaching and runoff are suspected as the primary sources for nutrient input to submarine groundwater to the south and northern parts of the West Coast, respectively.

L’étude des processus physiques d’un système d’upwelling est essentielle pour comprendre sa variabilité actuelle et ses changements passés et futurs. Cette thèse présente une étude interdisciplinaire du système d’upwelling côtier à partir de différentes données acquises par satellite, l’accent étant mis principalement sur le système d’upwelling d’Afrique du Nord-Ouest (NWA). Cette étude interdisciplinaire aborde (1) le problème de l’identification et de l’extraction automatiques du phénomène d’upwelling à partir d’observations satellitaires biologiques et physiques. (2) Une étude statistique de la variation spatio-temporelle de l’upwelling de la NWA tout au long de son extension et de ses différents indices d’upwelling. (3) Une étude des relations non linéaires entre le mélange de surface et l’activité biologique dans les régions d’upwelling. (4) études lagrangiennes de tourbillons cohérents; leurs propriétés physiques et identification automatique. (5) L’étude des transports effectués par les tourbillons lagrangiens de la NWA Upwelling et leur impact sur l’océan
Studying physical processes of an upwelling system is essential to understand its present variability and its past and future changes. This thesis presents an interdisciplinary study of the coastal upwelling system from different satellite acquired data, with the main focus placed on the North West African (NWA) upwelling system. This interdisciplinary study covers (1) the problem of the automatic identification and extraction of the upwelling phenomenon from biological and physical satellite observations. (2) A statistical study of the spatio-temporal variation of the NWA upwelling throughout its extension and different upwelling indices. (3) A Study of the nonlinear relationships between the surface mixing and biological activity in the upwelling regions. (4) Lagrangian studies of coherent eddies; their physical properties and automatic identification. (5) The study of transport made by Lagrangian eddies off the NWA Upwelling and their impact on the open ocean. [...]

Depuis 1939, une partie des pays de l'Afrique de l'Ouest a pour monnaie le Franc CFA d'Afrique de l'Ouest. Ces pays constituent, de fait, une zone monétaire. La dévaluation du CFA de 1994 marque le passage d'une convertibilité automatique à une convertibilité partielle. Il est alors légitime de s'interroger sur l'optimalité de cette zone monétaire surtout dans un contexte où la Zone Euro connaît elle même des difficultés.Elle a pour ambition de s'interroger sur l'optimalité de la zone monétaire l'Union Economique et Monétaire Ouest-Africaine. L'étude a donc pour objectif d'identifier si cette zone monétaire est une Zone Monétaire Optimale, (ZMO) au sens de MUNDELL (1961). L'objet d'étude soulevé ici portera plus particulièrement sur l'analyse des critères de faisabilité d'une ZMO et le passage à des critères de soutenabilité. Les critères de premier rang d'une ZMO, déterminés par les auteurs précurseurs de littérature sur la question dans les années 1960 et 1970, constitués principalement par les apports de MUNDELL, (1961).Notre travail propose de ne pas se limiter à la définition donnée par MUNDELL, même si cette théorie s'applique à juste titre pour des pays candidats à l'adhésion. Dans ce cas la Loi du Prix Unique permet de caractériser la fixité du taux de change comme étant une condition nécessaire de premier rang. Cette condition de premier ordre est non suffisante pour justifier de la soutenabilité et durabilité d'une zone. La fixité des monnaies est la deuxième condition retenue. La monnaie unique devient alors un choix rationnel qui se justifie par les avantages qu'elle procure aux pays qui l'adoptent
Ome of the West African countries have adopted the CFA Franc (Franc of African Financial Communities) as their currency in 1939. These countries hence form a monetary zone. The devaluation of the French CFA in 1994 marked the passage from an automatic convertibility to a partial convertibility. It seems legitimate to consider the optimality of the West-African currency area - especially in a context where the Euro zone itself faces difficulties.This thesis aims to identify whether this area is indeed an optimal currency area as defined by MUNDELL in 1961. The object of study raised here will focus more particularly on the analysis of the feasibility of an OCA (Optimum currency area) and on the passage to sustainability criteria. The primary criteria of an OCA -- as determined by the founding authors in the literature of the 1960s and 1970s on the issue, MUNDELL being the main contributor (1961). This study however does not restrict itself solely to the definition given by MUNDELL, even though his theory applies rightly to countries which are candidates to entry into the union. In this case, the Law of one Price (Loop) can characterize the fixity of the exchange rate as a primary necessary condition. This proviso however is not sufficient to justify the sustainability and durability of an area. In case this latter condition is not met, the other condition is the fixity of currencies. The unique currency then becomes a rational choice which is justified by the advantages it procures countries which adopt it

Since the study on the Port Alfred/Kenton-on-Sea/Boknes linefishery by Hecht and Tilney (1989) there have been substantive changes to the linefish management environment in South Africa. Using the Port Alfred linefishery as a model, the aim of this study was to evaluate the effectiveness of the linefish management regulations that were implemented by Marine and Coastal Management (MCM) since 1992, and to assess the behaviour and 'status' of the fishery in response to these changes. Changes to both the licensing structure and catch regulations have had a significant effect on the functioning of many aspects of the Port Alfred linefishery (fishing effort, catch composition, cpue) as well as on the structure of the fishery and its socio-economic profile. Overall commercial cpue decreased from 1985 to 1998. Since 1998 there has been a significant increase in cpue (from 2.3 Kg.fisher⁻¹ hour⁻¹ to a peak of 4.8 Kg.fisher⁻¹.hour⁻¹ in 2005. This was attributed to good catches of geelbek, particularly in 2005, 2007 and 2008 (during these years geelbek contributed an average of 35% to the total landings in comparison to a mean contribution of II % between 1985 and 2004). However, size spectra analysis suggests that the increase in overall cpue since 1998 misrepresents the actual status of the fishery. If geelbek is excluded from the analysis on the grounds that it is the only species in the fishery that is highly migratory, susceptible to recruitment fluctuations and it does not contribute to the catches on a year round basis, then the results suggest that the fishery is still in a declining phase despite the 80% reduction in commercial effort and numerous stricter catch regulations (e.g. size/bag limits). Furthermore, the cpue of silver kob, which has been the "mainstay" species of the fishery, has consistently declined over the last 23 year period (from 1.69 Kg.fisher⁻1 .hour1 in 1986 to 0.86 Kg.fisher⁻1.hour⁻1in 2007). The substantial reduction in commercial effort in the fishery from 33 vessels in 2001 to 13 in 2002 resulted in a shift from commercial to recreational fishing. The number of active commercial vessels in Port Alfred alone decreased from 29 in 1989 (Hecht 1993) to four in 2008. During the same timeframe, the number of regularly active recreational vessels had almost doubled (16 in 1989 to 26 in 2008). Despite the greater number of recreational boats in the fishery they only landed approximately half the average yearly tonnage of the commercial vessels (21,5 and 44,7 tonnes,annum-I , respectively) between 2006 and 2008, This was ascribed to the differences in catch regulations for the two sectors, Furthermore, it was speculated that increasing operating costs and narrowing profit margins have contributed to lower levels of compliance in both the commercial and recreational sectors since 2006, For example, 16% of silver kob landed during 2006-08 were under the minimum size, Despite the changes made to the regulations since 1998 and the 60,6% reduction In legislated commercial effort in the fishery between 2001 and 2002 it was concluded that the fishery has continued to decline, Except for the good recruitment of geelbek (which may be due to regulatory changes made in 1992) the changes in the management environment have had no measurable positive effect on this fishery, It is recommended that commercial effort should not be allowed to increase beyond the current number of active boats, that there should be an area restriction on all commerciallinefish vessels, that the current recreational bag limit for silver kob should be re-assessed, there should also be a concerted and nationally funded effort to educate recreational anglers about the merits of catch and release, and the frequency of catch inspections of both sectors should be increased,
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Cette thèse avait pour objectif de mieux comprendre le rôle de la dynamique océanique et atmosphérique régionale sur le fonctionnement de l’upwelling ouest africain. La première partie est consacrée à l’étude du cycle saisonnier, de la dynamique et de l’origine des masses d’eau du courant de bord qui alimente l’upwelling ouest africain. Ce courant est situé sur la pente continentale et est dénommé WABC (pour West African poleward Boundary Current en anglais). Son lien avec la circulation à l’échelle de l’Atlantique Tropical Nord Est (ATNE) est aussi étudié. Les résultats obtenus sont principalement basés sur des sorties de simulations numériques avec une configuration régionale du modèle NEMO (TROP025). Le WABC est constitué d’un sous courant dirigé vers le pôle (communément appelé Poleward Under Current (PUC) en anglais) et d’un courant de surface également dirigé vers le pôle et fréquemment appelé courant de Mauritanie (Mauritania Current en anglais ; MC). Le WABC est présent quasiment toute l’année. Il est visible en surface (en l’absence du jet d’upwelling côtier) et s’étend jusqu’à ~ 250 m de profondeur ou en gamme de densité. Son transport méridien vers le nord est la conséquence des gradients de pression baroclines mis en place par le vent et aussi d’un rotationnel de vent positif le long des côtes ouest africaines. L’étude du cycle saisonnier a permis de montrer que le WABC présente deux pics de transport dans l’année : un premier en Avril-Mai et un second en Octobre- Novembre. Ce cycle semi-annuel du WABC résulte de l’activité des ondes côtières générées par les fluctuations du forçage par le vent. Le premier pic est causé par une relaxation des vents locaux (dans la zone côtière ouest africaine). Pour le second pic automnal la zone de forçage est distante et principalement située dans le golfe de Guinée. La quantité d’eau transportée par le WABC est estimée à 1 Sv en moyenne annuelle. Du fait de la variation du paramètre de Coriolis avec la latitude (effet β), les ondes côtières associées à la variation du WABC donnent naissance à des ondes de Rossby se propageant vers l’ouest. Les caractéristiques de ces ondes qui changent suivant la latitude, sont mises en évidence dans la thèse. L’étude de l’origine des masses d’eau du WABC a permis de clarifier le lien entre le WABC et la circulation dans l’ATNE. En effet, les masses d’eau transportées par le WABC sont amenées par le sous courant nord équatorial et sont principalement situées dans la thermocline (100-240 m). Elles subissent de fortes recirculations et une advection moyenne faible (~1 cm/s) dans la "shadow zone" avant d’être amenées par le WABC. Cette étude nous a aussi permis de montrer que la circulation au nord du dôme de Guinée (notamment la recirculation vers l’ouest associée à la présence du dôme de Guinée) tend à être surestimée lorsque les vitesses sont calculées à partir de l’équation du vent thermique avec des niveaux de références peu profonds. En effet, la prise en compte des gradients thermohalins profonds est importante et tend à renforcer l’advection vers le nord-est dans l’ATNE. La dernière partie de la thèse a concerné l’étude des modes de variabilité atmosphérique grandes échelles qui modulent, aux échelles de temps synoptiques, l’intensité des vents d’upwelling le long des côtes sénégalaises. Les analyses menées sur des données de réanalyses (Era-Interim) montrent que les fluctuations du vent, à ces échelles de temps et dans cette zone, sont principalement liées à l’intensité et la position de l’anticyclone des Açores, de l’anticyclone Saharo-Libyen et de la dépression Saharo-sahélienne. La variabilité du régime de vent à Dakar en lien avec ENSO s’explique notamment par la manière dont ces centres d’action sont affectés par ce mode de variabilité climatique
The southern end of the Canary current system comprises of an original upwelling center that has so far received little attention. This Ph.D. Thesis focuses on the dynamical functioning of the Southern Senegal-Gambia Upwelling Center (SSUC). We are interested in the upwelling circulation and thermohaline structure on the shelf between the coastline and 100-200 km offshore. Our focus is on the upwelling period (November to May). The main originality of the SSUC compared to other upwelling centers stems from its conti-nental shelf that is broad and shallow (20–30 m over tens of kilometers). The normal state of the system comprises the classical upwelling front but also a well-defined inner-shelf front that separates cold upwelled waters from nearshore warmer waters. We investigate its dynamical functioning using analysed satellite images, in situ data and state-of-the- art 3D numerical simulations. Through a fine-scale analysis of the physical conditions of the SSUC, this work poses the basis of an integrated approach to the Senegalese marine environment functioning. A first part of results is based on the careful examinations and analysis of over 1500 satellite images of sea surface temperature scenes contextualized with respect to wind conditions. Analysis confirm the regularity and stability of the SSUC dynamical functioning (as manifested by the recurrence and persistence of particular SST patterns). The analyses also reveal subtle aspects of its upwelling structure : shelf break cooling of surface waters consistent with internal tide breaking/mixing ; complex interplay between local upwelling and the Mauritanian current off the Cape Verde headland ; complexity of the inner-shelf/mid shelf frontal transition. The amplitude of the diurnal cycle suggests that large uncertainties exist in the SSUC heat budget. The studies limitations underscore the need for continuous in situ measurement in the SSUC, particularly of winds. The dynamical functioning of SSUC is also investigated by means of numerical simulations, using the hydrodynamical Regional Ocean Modeling System ROMS (∆x ≈ 2 km). Different simulations have been carried with varying forcings (climatological or synoptic wind ; fine-scale adjustments of heat flux in coastal area ; presence or absence of tides). Numerical solutions show a good agreement with available satellite and in situ observations. These solutions clarify the dynamical functioning of the system especially in terms of circulation, location of cold water upwelling but also fate of upwelled water through a Lagrangian analysis. We show in particular that the northern part of the SSUC is the main upwelling area. Waters that upwelled in this area predominantly come from the southern of the SSUC, through advection by the Mauritanian current. Lagrangian analysis also revealed the dynamics associated with the coastal area of nursery and nuance the conceptual retention scheme previously admitted. The sensitivity of the dynamics of SSUC to atmospheric forcings is modest with nevertheless some modulations of the cross-shore exchanges that may be important to the ecosystem

On etudie les sediments recents de l'interface dans la baie des anges, la baie de villefranche-sur-mer et dans la reserve sous-marine du larvotto au large de monaco, afin de mettre en evidence les relations existant entre les processus diagenetiques et lithologiques d'une part et les proprietes physico-chimiques des sediments d'autre part. On observe en particulier la qualite de la matiere organique presente dans l'eau et les sediments ainsi que les relations entre m. O. Ou ses produits de desintegration et les metaux-traces. On analyse les variations spatio-temporelles des teneurs en sels nutritifs et en metaux-traces, leur differenciation en fonction des conditions d'oxydo-reduction. On determine les facteurs dominants controlant les processus geochimiques

L'architecture, la mise en place et la pétrogénèse du Massif du Kogue (Poli, Nord Cameroun) s'intègrent dans l'évolution tectonique et plutonique de la zone mobile panafricaine du Nord Cameroun. Intrusion dans les formations métamorphiques de Poli, le complexe plutonique de Kogue est formé de deux unités constituées par deux lignées de différenciation magmatique, d'affinité calco-alcaline. L'agencement et l'analyse des trajectoires des fluidalités planaires soulignent une mise en place syntectonique sous forme de dome diapir dans un couloir de cisaillement. L'état rhéologique des magmas granitique et dioritique, dans les zones de brèches magmatiques montre que ceux-ci sont contemporains et ont une mise en place synchrone

Yes
This paper examines real effective exchange rate (REER) responses to shocks in exchange rate determinants for the West African Monetary Zone (WAMZ) over the period 1980–2015. The analysis is based on a country-by-country VECM, and oil price, supply and demand shocks are identified using long run restrictions in a structural VAR model. We report significant differences in the response of REER to real oil price, productivity (supply) and demand preference shocks across these economies. In addition the relative contribution of these shocks to REER movements in the short and long run appears to be different across economies. Our findings suggest that the WAMZ countries are structurally different, and asymmetric shocks with inadequate adjustment mechanisms imply that a monetary union would be costly.

A dissertation submitted in fulfilment of the requirements for the degree of Master of Science in Geology to the Faculty of Science, at the University of the Witwatersrand, 2019
The Palaeoproterozoic Baoulé-Mossi domain of the West African Craton in north-central Ivory Coast is crosscut by a north-northeast trending Ferké Batholith, confined by first-order crustal-scale Ferké Shear Zone (FSZ). To present a geodynamic evolution of the FSZ, incorporation of strato-tectonic, geophysical, geochemical, geochronological revisions is pivotal. In the study region, crosscutting relationship resolved that the oldest unit is formed by gneiss that is uncomfortably overlain by volcano-sedimentary sequences which are intruded by post-basin granitoids, i.e. Ferké Batholith. Volcano-sedimentary sequences consist of conglomeratesandstone-siltstone-mudstone succession and meta-volcaniclastic greywacke unit. Intrusive units making up Ferké Batholith include granodioritic gneiss, granodiorite, granite, tonalite, diorite and pegmatite. U-Pb zircon analysis of samples from the orthogneiss gave a crystallization age of the orthogneiss at 2282 ± 4 Ma, and these were affected by Dext extensional phase around 2132 ± 12 Ma that resulted in basin formation. Fining-upwards volcano-sedimentary sequences were deposited in the extensional-subsiding setting between 2109–2079 Ma. At 2097 Ma, Ferké Batholith emplacement was coeval with the formation of the FSZ. Four main deformational events were recognised crosscutting these rock units. D1 is a progressive deformation event that is dominated by ductile-brittle structures that formed at ~2097 Ma, and is responsible for development of north-northeast trending sinistral shear zones, steeply dipping foliation (S1 and S1-C), sub-horizontal L1 lineation and tight F1 folds. Ferké Batholith emplacement is constrained between 2097 and 1842 Ma U-Pb ages supported by crosscutting relationships. U-Pb age of 2097 Ma constrains D1 and minimum age for deposition of metasedimentary units. Late D1 structures are defined by northwest trending sub-vertical displaced fractures. Northwest trending dilational jogs and sigmoidal en-echelon fractures were formed during late D1. D1 event is related to north-northwest and south-southeast directed principal compressive strain axis. The D2 structures comprise northwest trending F2 folds and foliation (S2) from refolding of D1 structures S1 and F1. Dextral sense of displacement from north-northeast trending shear zones and L2 lineation along the Ferké-Bandama branch developed during D2. West, northwest and west-northwest trending veins (V2) are associated with D2 deformation. Kinematic analysis indicated that the principal compressive strain axis was northnortheast or northeast directed during D2 deformation. iii Brittle fractures, including the northwest to west trending fractures and faults formed the third generation of structure (D3). The traces of D3 structures crosscut those of D1 and D2 features throughout the study area. Northwest sinistral en echelon structures and northeast trending displaced fractures correlate with D3 characteristics i.e. overall north-northeast to northeast maximum shortening direction. Geochemical data show that various granitoids making up the Ferké Batholith are true granites. These intrusive units geochemical character shows calc-alkaline affinities with a very high-K character, mostly I-type and peraluminous composition. Tectonic discrimination diagrams confine the batholith within syn-collision fields. Gold mineralisation associated with FSZ occurs in the metasedimentary units to the southwest (Tortiya region) and northeast (north of Kouloukorosso) of the Ferké Batholith. These regions are structurally controlled and spatially associated with FSZ and hydrothermal veins that formed in response to the regional extensional stress field. The shape of the batholith and/or shear zone sense of displacement permits releasing bends (normal faults) to develop in the regions of Tortiya and Kouloukorosso.
TL (2020)

L’étude des processus physiques d’un système d’upwelling est essentielle pour comprendre sa variabilité actuelle et ses changements passés et futurs. Cette thèse présente une étude interdisciplinaire du système d’upwelling côtier à partir de différentes données acquises par satellite, l’accent étant mis principalement sur le système d’upwelling d’Afrique du Nord-Ouest (NWA). Cette étude interdisciplinaire aborde (1) le problème de l’identification et de l’extraction automatiques du phénomène d’upwelling à partir d’observations satellitaires biologiques et physiques. (2) Une étude statistique de la variation spatio-temporelle de l’upwelling de la NWA tout au long de son extension et de ses différents indices d’upwelling. (3) Une étude des relations non linéaires entre le mélange de surface et l’activité biologique dans les régions d’upwelling. (4) études lagrangiennes de tourbillons cohérents; leurs propriétés physiques et identification automatique. (5) L’étude des transports effectués par les tourbillons lagrangiens de la NWA Upwelling et leur impact sur l’océan
Studying physical processes of an upwelling system is essential to understand its present variability and its past and future changes. This thesis presents an interdisciplinary study of the coastal upwelling system from different satellite acquired data, with the main focus placed on the North West African (NWA) upwelling system. This interdisciplinary study covers (1) the problem of the automatic identification and extraction of the upwelling phenomenon from biological and physical satellite observations. (2) A statistical study of the spatio-temporal variation of the NWA upwelling throughout its extension and different upwelling indices. (3) A Study of the nonlinear relationships between the surface mixing and biological activity in the upwelling regions. (4) Lagrangian studies of coherent eddies; their physical properties and automatic identification. (5) The study of transport made by Lagrangian eddies off the NWA Upwelling and their impact on the open ocean. [...]