L’étalement urbain au péril des activités agro-pastorales à Abidjan

L’urbanisation rapide, pose des défis de logement et d’alimentation à la communauté internationale dans son ensemble et particulièrement aux pays en voie de développement. A Abidjan en Côte d’Ivoire, le développement de la commune de Yopougon et la croissance démographique de près de 4 %, entrainent une importante pression sur les terres agricoles urbaines et périurbaines. La présente étude met en évidence l’influence de cet étalement urbain sur les activités agro-pastorales à Yopougon. Une démarche cartographique, suivie d’une démarche socio-anthropologique a été adoptée. Des entretiens avec questionnaires ont été effectués avec 93 agriculteurs. Cette étude montre que les activités agricoles se déroulent sur trois principaux sites : Lokoa, Béago et Azito. Entre 2004 et 2007, les sites agricoles ont connu une réduction d’environ 41 % de leurs superficies du fait de la croissance urbaine. La variation totale de superficie due aux constructions est de 40 % à Azito, 18 % à Lokoa et 8 % à Béago. Des parcs à bétails ont changé de position géographique et se retrouvent en bordure de lagune. L’étude montre également que 94 % des agriculteurs du site vivent principalement de l’agriculture urbaine et que l’insécurité foncière reste leur principale préoccupation. L’étalement spatial de la commune de Yopougon, contribue à une forte réduction des superficies agricoles rendant ainsi vulnérable les familles impliquées dans les activités agricoles comme principales sources de revenus.Rapid urbanization leads to challenges in housing and food access for all the international community and particularly in developing countries. In Abidjan, the developments of Yopougon municipality and population increase have caused significant pressure on agricultural lands and represent a danger for agriculture in the surrounding villages. The present study aims at highlighting the influence of urban spread on agro-pastoral activities in the district of Yopougon. A cartographic approach and a socio anthropologic approach were used. Observations and individual interviews were made with 93 agricultural actors. Agricultural activities were observed on three principal sites : Lokoa, Béago and Azito. Between 2004 and 2007, approximately 41 % of the agricultural surface was occupied by settlements. Total variation of surface due to settlements was 40 % at Azito, 18 % at Lokoa and 8 % at Béago. Some pastoral and cattle parks were joined by the city and were moved to other geographical positions. For 94 % of agricultural actors in the studied site, agriculture was the principal source of income and land insecurity remained the principal concern of the farmers. The urban sprawl of the municipality of Yopougon contributes to a strong reduction of agricultural surface. It makes agricultural actors vulnerable as it is their only source of income

Rapid decline of the CO2 buffering capacity in the North Sea and implications for the North Atlantic Ocean

Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Global Biogeochemical Cycles 21 (2007): GB4001, doi:10.1029/2006GB002825.New observations from the North Sea, a NW European shelf sea, show that between 2001 and 2005 the CO2 partial pressure (pCO2) in surface waters rose by 22 μatm, thus faster than atmospheric pCO2, which in the same period rose approximately 11 μatm. The surprisingly rapid decline in air-sea partial pressure difference (ΔpCO2) is primarily a response to an elevated water column inventory of dissolved inorganic carbon (DIC), which, in turn, reflects mostly anthropogenic CO2 input rather than natural interannual variability. The resulting decline in the buffering capacity of the inorganic carbonate system (increasing Revelle factor) sets up a theoretically predicted feedback loop whereby the invasion of anthropogenic CO2 reduces the ocean's ability to uptake additional CO2. Model simulations for the North Atlantic Ocean and thermodynamic principles reveal that this feedback should be stronger, at present, in colder midlatitude and subpolar waters because of the lower present-day buffer capacity and elevated DIC levels driven either by northward advected surface water and/or excess local air-sea CO2 uptake. This buffer capacity feedback mechanism helps to explain at least part of the observed trend of decreasing air-sea ΔpCO2 over time as reported in several other recent North Atlantic studies.S. Doney and I. Lima were supported by NSF/ONR NOPP (N000140210370) and NASA (NNG05GG30G)

Global data on earthworm abundance, biomass, diversity and corresponding environmental properties

14 p.Earthworms are an important soil taxon as ecosystem engineers, providing a variety of crucial ecosystem functions and services. Little is known about their diversity and distribution at large spatial scales, despite the availability of considerable amounts of local-scale data. Earthworm diversity data, obtained from the primary literature or provided directly by authors, were collated with information on site locations, including coordinates, habitat cover, and soil properties. Datasets were required, at a minimum, to include abundance or biomass of earthworms at a site. Where possible, site-level species lists were included, as well as the abundance and biomass of individual species and ecological groups. This global dataset contains 10,840 sites, with 184 species, from 60 countries and all continents except Antarctica. The data were obtained from 182 published articles, published between 1973 and 2017, and 17 unpublished datasets. Amalgamating data into a single global database will assist researchers in investigating and answering a wide variety of pressing questions, for example, jointly assessing aboveground and belowground biodiversity distributions and drivers of biodiversity change

Global data on earthworm abundance, biomass, diversity and corresponding environmental properties

Publisher Copyright: © 2021, The Author(s).Earthworms are an important soil taxon as ecosystem engineers, providing a variety of crucial ecosystem functions and services. Little is known about their diversity and distribution at large spatial scales, despite the availability of considerable amounts of local-scale data. Earthworm diversity data, obtained from the primary literature or provided directly by authors, were collated with information on site locations, including coordinates, habitat cover, and soil properties. Datasets were required, at a minimum, to include abundance or biomass of earthworms at a site. Where possible, site-level species lists were included, as well as the abundance and biomass of individual species and ecological groups. This global dataset contains 10,840 sites, with 184 species, from 60 countries and all continents except Antarctica. The data were obtained from 182 published articles, published between 1973 and 2017, and 17 unpublished datasets. Amalgamating data into a single global database will assist researchers in investigating and answering a wide variety of pressing questions, for example, jointly assessing aboveground and belowground biodiversity distributions and drivers of biodiversity change.Peer reviewe

Global data on earthworm abundance, biomass, diversity and corresponding environmental properties

Earthworms are an important soil taxon as ecosystem engineers, providing a variety of crucial ecosystem functions and services. Little is known about their diversity and distribution at large spatial scales, despite the availability of considerable amounts of local-scale data. Earthworm diversity data, obtained from the primary literature or provided directly by authors, were collated with information on site locations, including coordinates, habitat cover, and soil properties. Datasets were required, at a minimum, to include abundance or biomass of earthworms at a site. Where possible, site-level species lists were included, as well as the abundance and biomass of individual species and ecological groups. This global dataset contains 10,840 sites, with 184 species, from 60 countries and all continents except Antarctica. The data were obtained from 182 published articles, published between 1973 and 2017, and 17 unpublished datasets. Amalgamating data into a single global database will assist researchers in investigating and answering a wide variety of pressing questions, for example, jointly assessing aboveground and belowground biodiversity distributions and drivers of biodiversity change

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Dynamics of dioxide carbon and methane in some tropical ecosystems (Mangroves of Ca Mau, Rivers and lagoons from Ivory Coast)

Tropical near-shore coastal ecosystems receive 60% of the world freshwater and an equivalent fraction of organic matter. Thus, these regions are expected to have a major role in the overall budgets of CO2 and CH4, two major greenhouse gases, in the coastal and global oceans. As a contribution to the understanding of the role of the coastal ocean and continental aquatic environments in the global cycle of these gases, we report the seasonal variability of partial pressure of CO2 (pCO2), CH4 concentration, related air-water fluxes of CO2 and CH4 and ancillary data in several contrasted tropical coastal ecosystems in terms of geomorphology, lithology of the drainage basin, freshwater and seawater inputs, and riparian population and related anthropogenic pressure (land use change, aquaculture, waste waters release, eutrophication, and invasive species proliferation). We investigated waters surrounding two forested mangrove sites (Tam Giang and Kiên Vàng) located in Ca Mau Province (South-West Vietnam), in five lagoons (Grand-Lahou, Ebrié, Potou, Aby and Tendo) and three rivers (Comoé, Bia and Tanoé) flowing into these lagoons in Ivory Coast. Data from the two forested mangrove sites in South-West Vietnam were obtained during the dry and rainy seasons, providing for the first time information on the seasonality of dissolved inorganic carbon (DIC) and air-water CO2 fluxes in the water surrounding mangrove ecosystems. Our data suggest an increase of heterotrophic activity in sediments and/or the water column during the rainy season that could be due to an increase of carbon inputs from soil flushing, probably from the land surrounding the mangrove forests. The airwater CO2 fluxes we computed are consistent with the few data available so far in waters surrounding mangrove forests, and confirming that this emission of CO2 is significant for the carbon budget of mangrove forests, and also for the regional CO2 budget at tropical and subtropical latitudes. Data in lagoons and rivers of Ivory Coast were obtained during four cruises covering the main climatic seasons (high dry season, high rainy season, low dry season and low rainy season). The three rivers were oversaturated in CO2 and CH4 with respect to atmospheric equilibrium, and the seasonal variability of pCO2 and CH4 concentrations was due to dilution during the flooding period. The invasive floating hyacinth Eichhornia crassipes that cover these rivers can significantly contribute to the CO2 emission to the atmosphere from the aquatic compartment due to root respiration and organic matter degradation derived from these plants. However, floating macrophytes are atmospheric CO2 sinks. The surface waters of the Potou, Ebrié and Grand-Lahou lagoons were oversaturated in CO2 and CH4 with respect to the atmosphere during all seasons. In contrast, the Aby and Tendo lagoons exhibit enhanced over-saturation in CH4 but under-saturation in CO2 because of their permanent haline stratification (unlike the other lagoons) that seemed to lead to higher phytoplankton production and export of organic carbon below the pycnocline. However, the permanent stratification also leads to anoxic bottom waters favorable to a large CH4 production. Thus, the largest CH4 over-saturations and diffusive air-water CH4 fluxes were observed in the Tendo and Aby lagoons while they can act as a sink for atmospheric CO2. We highlight the importance of physical settings (permanent versus seasonal stratification) in controlling the organic C flows, modulating the atmospheric CO2 source-sink status, and the intensity of CH4 emissions to the atmosphere in these near-shore coastal ecosystems

Confrontation avec le contexte disciplinaire institutionnalisé : réflexion critique des approches écosystémiques de la santé sur la base des expériences des jeunes chercheurs au Canada, en Afrique occidentale et centrale et en Amérique centrale

Les expériences des étudiants, jeunes chercheurs et professionnels formés en approches écosystémiques de la santé (AÉS) offrent des perspectives nouvelles sur le défi de changer le monde dans lequel nous évoluons. Guidées par les piliers que sont la transdisciplinarité, la participation, ainsi que l’équité de genre et sociale, les AÉS cherchent à répondre adéquatement aux problématiques complexes liant l'environnement et la santé. Cependant, la mise en œuvre de ces piliers sur le terrain pose des défis de taille qui ne peuvent pas être compris en dehors du contexte institutionnel qui encadre la relation entre chercheurs et communauté. En effet, ce qui peut paraître de menus détails – par exemple, l’arrivée sur le terrain, la prise de contact avec la communauté, la présentation et l’appropriation du projet de recherche, la collecte de données, etc. – reste intimement lié au mode de production des connaissances dominé par la structure disciplinaire et les conditions politico-économiques par lesquelles s’opère la rencontre entre les chercheurs et la communauté. À partir de 28 entretiens avec des étudiants gradués et de jeunes professionnels formés en AÉS en Afrique de l’Ouest et du Centre, en Amérique centrale et au Canada, ainsi que par des observations sur le terrain de projets en AÉS, cet article vise à tracer les défis de monter un projet en AÉS en tenant compte du contexte institutionnel dominant. Après un aperçu théorique et historique des AÉS, nous présentons quelques-uns des principaux défis qui ont émergé des efforts pour mettre les AÉS en pratique. Puis, en situant ces défis dans leur contexte institutionnel plus large, nous tirerons les conséquentes politiques clés pour offrir quelques pistes sur la façon dont les résultats de notre analyse pourraient être exploités par d’autres groupes qui travaillent sur des thématiques à l’interface de l'environnement et de la santé.The experiences of students, young researchers and professionals trained in ecosystem approaches to health (ecohealth) offer new perspectives on the challenge of changing the world in which we live. Guided by the pillars of transdisciplinarity, participation and social/gender equity, ecohealth aims to effectively intervene in complex problems linking environment and health. However, putting these pillars into practice in the field raises challenges that cannot be adequately understood outside of the institutional context that frames the relationship between researchers and the community. What may seem like minor details – for example, arriving in the field, making contact with the community, presenting the research project, collecting data, etc. – remain intimately connected to the mode of knowledge production dominated by the disciplinary structure and current political-economic conditions through which the encounter between researchers and the community occurs. Based on 28 interviews with graduate students and young professionals trained in ecohealth in West and Central Africa, Central America and Canada, and based on observations of ecohealth projects on the ground, this article aims to trace the challenges of mounting an ecohealth project while taking into account the dominant institutional context. After a brief overview of the theory and history of ecohealth, we present some of the main challenges that emerged from efforts to put ecohealth into practice. After situating these challenges into their wider institutional context, we point out key implications and propose certain new policy directions that should prove relevant to other groups working at the interface of environment and health

Confrontation avec le contexte disciplinaire institutionnalisé : réflexion critique des approches écosystémiques de la santé sur la base des expériences des jeunes chercheurs au Canada, en Afrique occidentale et centrale et en Amérique centrale

The experiences of students, young researchers and professionals trained in ecosystem approaches to health (ecohealth) offer new perspectives on the challenge of changing the world in which we live. Guided by the pillars of transdisciplinarity, participation and social/gender equity, ecohealth aims to effectively intervene in complex problems linking environment and health. However, putting these pillars into practice in the field raises challenges that cannot be adequately understood outside of the institutional context that frames the relationship between researchers and the community. What may seem like minor details – for example, arriving in the field, making contact with the community, presenting the research project, collecting data, etc. – remain intimately connected to the mode of knowledge production dominated by the disciplinary structure and current political-economic conditions through which the encounter between researchers and the community occurs. Based on 28 interviews with graduate students and young professionals trained in ecohealth in West and Central Africa, Central America and Canada, and based on observations of ecohealth projects on the ground, this article aims to trace the challenges of mounting an ecohealth project while taking into account the dominant institutional context. After a brief overview of the theory and history of ecohealth, we present some of the main challenges that emerged from efforts to put ecohealth into practice. After situating these challenges into their wider institutional context, we point out key implications and propose certain new policy directions that should prove relevant to other groups working at the interface of environment and health