1. Gaetani M., Janicot Serge, Vrac M., Famien A. M., Sultan Benjamin. (2020). Robust assessment of the time of emergence of precipitation change in West Africa. Scientific Reports – Nature, 10 (1).http://dx.doi.org/10.1038/s41598-020-63782-2
    The time of emergence (TOE) of climate change is defined as the time when a new climate state emerges from a prior one. TOE assessment is particularly relevant in West Africa, a region highly threatened by climate change and urgently needing trustworthy climate predictions. In this paper, the TOE of precipitation change in West Africa is assessed for the first time, by analyzing 6 precipitation metrics (cumulated precipitation, number of wet and very wet days, onset and length of the rainy season) computed from the output of 29 state-of-the-art climate models. In West Sahel, climate conditions characterized by reduced occurrence of wet days are likely to emerge before 2036, leading to the possible emergence of a dryer climate in 2028-2052. In East Sahel, a wetter precipitation regime characterized by increased occurrence of very wet days is likely to emerge before 2054. Results do not provide a clear indication about a possible climate shift in the onset and length of the rainy season. Although uncertainty in climate model future projections still limits the robust determination of TOE locally, this study provides reliable time constraints to the expected climate shift in West Africa at the sub-regional scale, supporting adaptation measures to the future change in the precipitation regime.Affiliation IRD : UMR 182 (LOCEAN) ; UMR 228 (ESPACE-DEV)Copublication Sud avec : Côte d’ivoireLien Horizon FDI : http://www.documentation.ird.fr/hor/fdi:010078080
    Descr. géo. Horizon : AFRIQUE DE L’OUEST ; SAHEL
  2. Gobinddass M. L., Molinie J., Richard S., Panechou K., Jeannot A., Jean-Louis S. (2020). Coastal Sea Salt Chlorine Deposition Linked to Intertropical Convergence Zone (ITCZ) Oscillation in French Guiana. Journal of the Atmospheric Sciences, 77 (5), 1723-1731.http://dx.doi.org/10.1175/jas-d-19-0032.1
    Sea salt chloride is a major component of atmospheric aerosol and its behavior is an essential element in determining the climate. Two atmospheric chlorine deposition measurement procedures were performed between 2004 and 2008 by the French Guiana Regional Air Observatory (ORA), in the coastal plain of Sinnamary. The main goal was to determine the background spatial distribution of marine chlorine in order to evaluate the impact of Ariane rocket hydrogen chloride emission. To determine the chlorine concentration level, weekly samples from 10 sites were analyzed. A seasonal pattern was identified. For every site, a high sea salt chlorine deposition level was observed from December to April and a low level from July to October. The ratio of high to low mean chloride concentration R-HC/LC shows that just under half of the variation in chlorine deposition can be linked to the variation of sea salt production with low-level wind speed. Equations relating mean sea salt chlorine concentration and the distance to shore were studied, taking into account parameters found in other tropical regions, with a focus on neighboring Brazil. The wind rotation between the two seasons, and the sea salt chlorine loss per kilometer equation found for dry deposition, were used to calculate R-HC/LC. It appears that the observed rotation (60 degrees) explains 88% of R-HC/LC. Finally, inland sea salt chlorine deposition behavior in this region was linked to intertropical convergence zone oscillation through variations in wind speed and direction.Affiliation IRD : UMR 228 (ESPACE-DEV)
  3. Mosnier E., Dusfour I., Lacour G., Saldanha R., Guidez A., Gomes M. S., Sanna A., Epelboin Y., Restrepo J., Davy D., Demar M., Djossou F., Douine M., Ardillon V., Nacher M., Musset L., Roux Emmanuel. (2020). Resurgence risk for malaria, and the characterization of a recent outbreak in an Amazonian border area between French Guiana and Brazil. BMC Infectious Diseases, 20 (1).http://dx.doi.org/10.1186/s12879-020-05086-4
    Background In 2017, inhabitants along the border between French Guiana and Brazil were affected by a malaria outbreak primarily due to Plasmodium vivax (Pv). While malaria cases have steadily declined between 2005 and 2016 in this Amazonian region, a resurgence was observed in 2017. Methods Two investigations were performed according to different spatial scales and information details: (1) a local study on the French Guiana border, which enabled a thorough investigation of malaria cases treated at a local village health center and the entomological circumstances in the most affected neighborhood, and (2) a regional and cross-border study, which enabled exploration of the regional spatiotemporal epidemic dynamic. Number and location of malaria cases were estimated using French and Brazilian surveillance systems. Results On the French Guianese side of the border in Saint-Georges de l’Oyapock, the attack rate was 5.5% (n = 4000), reaching 51.4% (n = 175) in one Indigenous neighborhood. Entomological findings suggest a peak of Anopheles darlingi density in August and September. Two female An. darlingi (n = 1104, 0.18%) were found to be Pv-positive during this peak. During the same period, aggregated data from passive surveillance conducted by Brazilian and French Guianese border health centers identified 1566 cases of Pv infection. Temporal distribution during the 2007-2018 period displayed seasonal patterns with a peak in November 2017. Four clusters were identified among epidemic profiles of cross-border area localities. All localities of the first two clusters were Brazilian. The localization of the first cluster suggests an onset of the outbreak in an Indigenous reservation, subsequently expanding to French Indigenous neighborhoods and non-Native communities. Conclusions The current findings demonstrate a potential increase in malaria cases in an area with otherwise declining numbers. This is a transborder region where human mobility and remote populations challenge malaria control programs. This investigation illustrates the importance of international border surveillance and collaboration for malaria control, particularly in Indigenous villages and mobile populations.Affiliation IRD : UMR 259 (SESSTIM) ; (sans mention d’UMR) ; UMR 228 (ESPACE-DEV)Copublication Sud avec : BrésilLien Horizon FDI : http://www.documentation.ird.fr/hor/fdi:010078146
    Descr. géo. Horizon : GUYANE FRANCAISE ; BRESIL ; AMAZONIE
  4. Mury A., Collin A., Jeanson M., James D., Gloria H., Pastol Y., Etienne S. (2020). Mapping Nature-based Marine Flooding Risk using VHR Wave, Airborne LiDAR and Satellite Imagery: The Case Study of the Dol Marsh (Bay of Mont-Saint-Michel, France). Journal of Coastal Research, (95), 743-747.http://dx.doi.org/10.2112/si95-145.1
    A growing interest in nature-based solutions has gained unprecedented attention in the coastal risk management, to complement or replace conventional approaches like hard structures (dykes, seawalls, breakwaters). However, due to the diversity of coastal ecosystems and the heterogeneity of the ecosystem service of wave attenuation they can induce, the integration of their protective role in an accurate way into risk studies remains rare. This paper shows an experimental methodology to integrate this ecosystem service into the risk mapping at very high spatial resolution using in situ sensors, airborne LiDAR and spaceborne satellite imagery. Risk study is achieved using a combination of indices which allows to evaluate the asset’s exposure and vulnerability. The nature-based solution is also integrated through the creation of an adaptive capacity index, based on a spatially-explicit model of wave attenuation. The study enables to highlight the assets which are the most concerned by the marine flooding risk, using a synthetic risk index ranging from 0 to 1.Affiliation IRD : UMR 228 (ESPACE-DEV)
  5. Proudfoot B., Devillers Rodolphe, Brown C. J., Ediner E., Copeland A. (2020). Seafloor mapping to support conservation planning in an ecologically unique fjord in Newfoundland and Labrador, Canada. Journal of Coastal Conservation, 24 (3).http://dx.doi.org/10.1007/s11852-020-00746-8
    As human impacts continue to threaten coastal habitats and ecosystems, marine benthic habitat and substrate mapping has become a key component of many conservation and management initiatives. Understanding the composition and extent of marine habitats can inform marine protected area (MPA) planning and monitoring, help identify vulnerable or rare habitats and support fisheries management. To support conservation planning in Eastern Canada, we mapped the seafloor of Newman Sound, identifying the benthoscape classes (i.e. discrete biophysical seafloor classes) of this ecologically diverse and unique fjord in Newfoundland and Labrador (NL). Mapping was achieved using multibeam echosounder (MBES) data collected using multiple platforms, seafloor videos and an unsupervised pixel-based classification method. Seven benthoscape classes were identified within the extent of the MBES coverages. Multivariate statistical analyses indicate that two benthoscape classes – mixed boulder and mud – support distinct epifaunal communities, and also capture the changes in benthic community composition between hard/shallow substrates and soft/deep substrates. Our results illustrate how benthoscape maps can inform marine spatial planning and conservation in the Newman Sound region, support monitoring and also calls for adaptive management of the adjacent Eastport MPA.Affiliation IRD : UMR 228 (ESPACE-DEV)Lien Horizon FDI : http://www.documentation.ird.fr/hor/fdi:010078137
    Descr. géo. Horizon : CANADA ; TERRE NEUVE ; LABRADOR
  6. Proudfoot B., Devillers Rodolphe, Brown C. J. (2020). Integrating fine-scale seafloor mapping and spatial pattern metrics into marine conservation prioritization. Aquatic Conservation : Marine and Freshwater Ecosystems, [Early access].http://dx.doi.org/10.1002/aqc.3360
    Marine protected area (MPA) planning often relies on scientific principles that help ensure that an area selected for conservation will effectively protect biodiversity. Capturing ecological processes in MPA network planning has received increased attention in recent years. High-resolution seafloor maps, which show patterns in seafloor bio-physical characteristics, can support our understanding of ecological processes. In part, owing to a global lack of high-resolution seafloor maps, studies that aim to integrate seascape spatial pattern and conservation prioritization often focus on shallow biogenic habitats with less attention paid to deeper benthic seascapes (benthoscapes) mapped using acoustic techniques. Acoustic seafloor mapping strategies yield the spatial information required to extend conservation prioritization research into these environments, making incorporating seafloor ecological processes into conservation prioritization increasingly achievable. Here, a new method is proposed and tested that combines benthoscape mapping, landscape ecology metrics and a conservation decision support tool to prioritize areas with structural and potential connectivity value in MPA placement. Using a case study in eastern Canada, benthoscape composition and configuration were quantified using spatial pattern metrics and integrated into Marxan. Results illustrate how large patches of seafloor habitat in close proximity to neighbouring patches can be preferentially selected when benthoscape configuration is considered. The flexibility of the method for including relevant spatial pattern metrics or species-specific movement data is discussed to illustrate how benthic habitat maps can improve existing conservation planning methods and complement existing and future work to support marine biodiversity conservation.Affiliation IRD : UMR 228 (ESPACE-DEV)Lien Horizon FDI : http://www.documentation.ird.fr/hor/fdi:010078101
  7. Tran A., Mangeas Morgan, Demarchi M., Roux Emmanuel, Degenne P., Haramboure M., Le Goff GilbertDamiens DavidGouagna Louis-ClémentHerbreteau Vincent, Dehecq J. S. (2020). Complementarity of empirical and process-based approaches to modelling mosquito population dynamics with Aedes albopictus as an example : application to the development of an operational mapping tool of vector populations. PLoS One, 15 (1).http://dx.doi.org/10.1371/journal.pone.0227407
    Mosquitoes are responsible for the transmission of major pathogens worldwide. Modelling their population dynamics and mapping their distribution can contribute effectively to disease surveillance and control systems. Two main approaches are classically used to understand and predict mosquito abundance in space and time, namely empirical (or statistical) and process-based models. In this work, we used both approaches to model the population dynamics in Reunion Island of the ‘Tiger mosquito’, Aedes albopictus, a vector of dengue and chikungunya viruses, using rainfall and temperature data. We aimed to i) evaluate and compare the two types of models, and ii) develop an operational tool that could be used by public health authorities and vector control services. Our results showed that Ae. albopictus dynamics in Reunion Island are driven by both rainfall and temperature with a non-linear relationship. The predictions of the two approaches were consistent with the observed abundances of Ae. albopictus aquatic stages. An operational tool with a user-friendly interface was developed, allowing the creation of maps of Ae. albopictus densities over the whole territory using meteorological data collected from a network of weather stations. It is now routinely used by the services in charge of vector control in Reunion Island.Affiliation IRD : UMR 228 (ESPACE-DEV) ; UMR 224 (MIVEGEC)Lien Horizon FDI : http://www.documentation.ird.fr/hor/fdi:010078087
    Descr. géo. Horizon : REUNION