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The Bluntnose scorpionfish Neomerinthe erostris is recorded for the first time from Mayotte, southwestern Indian Ocean, based on a specimen photographed in November 2022, at a depth of 115 m. The live colour pattern of this species is described for the first time.

Cet article propose d’aborder les nouvelles dynamiques de la parentalité à Mayotte au prisme de la figure des « enfants du juge », considérée, dans cette société en profonde mutation, comme le symbole d’un glissement dans les représentations de l’enfance et de l’éducation. À la lumière des analyses d’Esther N. Goody sur la parentalité et le confiage d’enfants, nous montrons qu’à Mayotte, la délégation croissante de ces rôles éducatifs aux services de l’État, qui apparaît comme un nouvel éducateur aux yeux des familles, est problématique. Départementalisée depuis 2011, Mayotte est confrontée à une vision allogène de l’enfance en danger, inspirée par le droit commun français. Le regard des institutions métropolitaines sur l’enfance s’appuie sur des références normatives qui entrent en concurrence avec l’éducation traditionnelle mahoraise. This article proposes to approach the new dynamics of parenthood in Mayotte through the prism of the figure of the “judge’s children,” considered as the symbol of a shift in representations of childhood and education in a society undergoing profound change. In the light of Esther N. Goody’s work on parenthood and fostering children, we show that in Mayotte the increasing delegation of these educational roles to the services of the State, which appears as a new educator in the eyes of families, is problematic. Departmentalized since 2011, Mayotte is faced with an allogenic vision of childhood in danger, imported by French common law. The view of metropolitan institutions on childhood is based on normative references that compete with traditional Mahoran education.

The issue of ethnicity has always been a controversial one, especially in France — whether on the mainland in relation to regional minorities or migrants, or in the French overseas territories. As a former colonial Empire and an epitome of secular republicanism, France resists use of any ethnic identification, including in the academic world and anthropology. This topical collection reconsiders this position and takes stock of the “ethnic situations” in relation to the new postcolonial and post-socialist historical conditions, the generalisation of the global market, the accelerated movement of goods and people, as well as the intensification of the diasporic phenomenon. The various contributions provide insights into specific ethnic affiliations, seen from the inside, in diverse ethnographic fields related to migration to France, from Senegal, Morocco, Comoros, Asia, or within the framework of particular French institutions.This editorial seeks to give space to consideration of the issue of ethnicity, emancipating it from its current national suppression in France, by connecting it to other currents of thought developed by non-French, French-speaking sociologists, such as Danielle Juteau, and English-speaking sociologists, in particular Jean and John Comaroff, who have addressed this topical collection in diverse national contexts (Quebec, United States, South Africa, China, etc.). The authors of this editorial and coordinator of this topical collection emphasise that ethnic affiliations show a real capacity of adaptation, paradoxically using it as a means of integration into the French urban economy and republican landscape, as a way to promote their form of citizenship. They show how this sociological category can be interpreted by individuals in a rigid way, or with openness to other ethnic markers, thus demonstrating “transethnic competence”. They conclude that, far from being an archaism, ethnic dynamics are always at work in contexts dominated by national representations. Moreover, ethnic identification, one of the modalities of perception of otherness, which should not be limited to minorities as it also concerns majority groups, deserves a specific approach, distinct from race and discrimination. This editorial and topical collection of the Revue Européenne des Migrations Internationales seek to contribute, from the perspective of the case of France to the general and international reflection on the processes of ethnic differentiation in a globalised world. ethnic, ethnicity, ethno-nations, minorities, majorities, migration, diasporas, circulation, imagination, market, globalisation, associations, hospital, religion, race, Asians, Moroccans, France, Senegal, Mayotte, Comoros La question ethnique a toujours été polémique, en particulier en France — que ce soit dans l’« Hexagone » envers les cultures régionales ou migrantes, ou dans les territoires d’outre-mer. En tant qu’ancien Empire colonial et incarnation d’un républicanisme laïque, cette nation résiste à tout pratique d’identification ethnique, y compris dans le monde de la recherche et en anthropologie. Ce dossier se propose de dépasser cette position et de prendre en considération les « situations ethniques » en relation avec les nouvelles conditions historiques postcoloniales et postsocialistes, la généralisation du marché global, la circulation accélérée des biens et des personnes et la multiplication des diasporas. Les différentes contributions fournissent des perspectives de l’intérieur des appartenances ethniques relevant de divers terrains ethnographiques tous en relation avec des migrations vers la France, issues du Sénégal, Maroc, Comores, Asie, ou dans le cadre d’institutions françaises spécifiques. Cet éditorial entend donner sa place à la question ethnique, au-delà de son refoulement national, en l’intégrant à d’autres courants de pensée portés par des sociologues de langue française mais non français comme Danielle Juteau, ou de référence anglo-américaine comme Jean et John Comaroff, qui l’ont traité dans d’autres contextes nationaux (Québec, États-Unis, Afrique du Sud, Chine, etc.). Les autrices de cet éditorial et coordinatrices de ce dossier thématique mettent en évidence que les affiliations ethniques font preuve d’une réelle capacité d’adaptation, l’utilisent paradoxalement comme moyen de participation à l’économie urbaine et au paysage républicain, promouvant ainsi leur forme de citoyenneté. Elles montrent que la catégorie sociologique ethnique peut être interprétée par les individus de façon rigide mais aussi ouverte, par l’adoption d’autres marqueurs ethniques que ceux adoptés pendant leur socialisation première, faisant ainsi preuve de « compétence transethnique ». Elles concluent que loin de s’apparenter à un archaïsme, les dynamiques ethniques sont toujours à l’œuvre dans des contextes dominés par les représentations nationales. L’identification ethnique, une des modalités de la perception de l’altérité, ne saurait cependant être limitée aux minorités et concerne tout aussi bien les groupes majoritaires ; elle mérite une attention spécifique, distincte de la race ou de la discrimination. Cet éditorial et ce dossier de la Revue Européenne des Migrations Internationales cherchent à participer, du point de vue de l’intérieur du cas français, à la réflexion générale et internationale sur les processus de différenciation ethnique dans un monde globalisé. La cuestión étnica siempre ha sido polémica, particularmente en Francia — sea en Francia metropolitana con las culturas regionales o migrantes, o en los territorios franceses de ultramar. Como antiguo Imperio colonial y como representación de un republicanismo laico, esta nación resiste toda práctica de identificación étnica, incluso en el ámbito de la investigación y de la antropología. Este dosier de la Revue Européenne des Migrations Internationales se propone ir más allá de esta posición y tener en cuenta las «situaciones étnicas» en relación con las nuevas condiciones históricas poscoloniales y postsocialistas, la generalización del mercado global, la circulación acelerada de mercancías y de personas, así como la multiplicación de las diásporas. Las diferentes contribuciones proporcionan perspectivas desde el interior de los grupos étnicos que atañen a terrenos etnográficos diversos, todos en relación con migraciones hacia Francia, provenientes de Senegal, Marruecos, las Comoras, Asia, o en el marco de instituciones francesas específicas. Este editorial pretende legitimar la cuestión étnica, más allá de su rechazo nacional, incorporándola a otros corrientes de pensamiento defendidos por sociólogos francófonos que no sean franceses como Danielle Juteau, o de referencia anglo-americana como Jean y John Comaroff, quienes la utilizaron en otros contextos nacionales (Quebec, Estados Unidos, Sudáfrica, China, etc.). Las autoras de este editorial y las coordinadoras de este número destacan el hecho de que las afiliaciones étnicas demuestran una verdadera capacidad de adaptación, la usan de manera paradójica como medio de participación en la economía urbana y en el panorama republicano, impulsando así su forma de ciudadanía. Demuestran que los individuos pueden interpretar la categoría sociológica étnica tan de manera rígida como de manera abierta, por la adopción de indicadores étnicos diferentes de los adoptados durante su primera socialización, así que dan muestras de «competencia transétnica». Concluyen que lejos de parecerse a un arcaísmo, las dinámicas étnicas siguen en acción en contextos predominados por las representaciones nacionales. Sin embargo, la identificación étnica, que es una de las modalidades de la percepción de la alteridad, no se podría limitar a las minoridades y concierne también a los grupos mayoritarios; merece una atención específica, distinta a la raza o a la discriminación. Este editorial y este número procuran participar, desde el punto de vista interior del caso francés, en la reflexión general e internacional en cuanto a los procesos de diferenciación étnica en un mundo globalizado.

Que signifie incarner l’État à Mayotte lorsque l’on est natif·ve de l’ancienne métropole coloniale et catégorisé·e comme blanc·he ? Et comment se positionnent les fonctionnaires métropolitain·es en poste dans ce territoire demeuré sous la souveraineté française lors des décolonisations du xxe siècle et devenu département d’outre-mer en 2011 ? Pour présenter les parcours d’agent·es muté·es depuis l’Hexagone, nous mobilisons la notion de blanchité, et montrons que les avantages structurels dont ils et elles bénéficient dans la poursuite de leurs carrières s’articulent à des privilèges symboliques fondés sur la race. Alors que la hiérarchie administrative est marquée par une forte ségrégation verticale, la posture faite d’extériorité vertueuse des agent·es métropolitain·es vient renforcer leurs positions dominantes au sein des services de l’État, tandis que diverses formes de disqualification contribuent parallèlement à l’exclusion des Mahorais·es, natif·ves de l’île, des postes les plus qualifiés. La blanchité constitue ici une propriété sociale discriminante, au sein d’un État postcolonial pourtant réputé aveugle à la race.

SUMMARY Airborne systems collecting transient electromagnetic data are able to gather large amounts of data over large areas in a very short time. These data are most often interpreted through 1-D inversions, due to the availability of robust, fast and efficient codes. However, in areas where the subsurface contains complex structures or large conductivity contrasts, 1-D inversions may introduce artefacts into the models, which may prevent correct interpretation of the results. In these cases, 2-D or 3-D inversion should be used. Here, we present a 2.5-D inversion code using 3-D forward modelling combined with a 2-D model grid. A 2.5-D inversion is useful where the flight lines are spaced far apart, in which case a 3-D inversion would not add value in relation to the added computational cost and complexity. By exploiting the symmetry of the transmitter and receiver system we are able to perform forward calculations on a reduced 3-D mesh using only half the domain transecting the centre of the transmitter and receiver system. The forward responses and sensitivities from the reduced 3-D mesh are projected onto a structured 2-D model grid following the flight direction. The difference in forward calculations is within 1.4 per cent using the reduced mesh compared to a full 3-D solution. The inversion code is tested on a synthetic example constructed with complex geology and high conductivity contrasts and the results are compared to a 1-D inversion. We find that the 2.5-D inversion recovers both the conductivity values and shape of the true model with a significantly higher accuracy than the 1-D inversion. Finally, the results are supported by a field case using airborne TEM data from the island of Mayotte. The inverted flight line consisted of 418 soundings, and the inversion spent an average of 6750 s per iteration, converging in 16 iterations with a peak memory usage of 97 GB, using 18 logical processors. In general, the total time of the 2-D inversions compared to a full 3-D inversion is reduced by a factor of 2.5 while the memory consumption was reduced by a factor of 2, reflecting the half-mesh approach.

International audience; From 10 May 2018 to 1 November 2022 (time of writing), an unprecedented seismic activity is observed east of Mayotte Island (France), related to the largest submarine eruption ever recorded with offshore geophysical studies. Using signals from regional and local seismic stations, we build a comprehensive catalog of the local seismicity for the first ten months of the sequence. This catalog includes a total of 2874 events of magnitude (Mlv) ranging from 2.4 to 6.0, with 77% of them relocated using a double difference location procedure. The hypocentral locations over this period are highly dependent on the small seismic network available. Therefore we compare the locations of later events using a similar network and those estimated from a local ocean bottom seismometer (OBS) network installed since March 2019. Based on the time space evolution and characteristics of the seismicity, five distinct phases can be identified, corresponding to the successive activation of two deep seismic swarms, related to the lithospheric-scale magma ascent up to the seafloor, along with progressive deepening of the seismicity interpreted as decompression of a 40 km deep reservoir.

International audience; Unlike subaerial volcanic activity, deep submarine eruptions are difficult to detect, observe and monitor. The objective of this paper is to describe a large and complex volcanic region, named the Horseshoe area, recently discovered at 1500 m below sea level on the eastern upper submarine slope of Mayotte Island. The area is crucial because, since 2018, it has experienced an exceptionally deep seismic activity associated with the ongoing submarine eruption that formed a new volcanic edifice, Fani Maoré, about 40 km to the east. We present the results of a multiscale study, based on high-resolution bathymetry and in-situ seafloor observations carried out with autonomous underwater vehicles (AUVs) and deep-towed camera systems. In-situ imagery provides ground-truth for the geological interpretation of seafloor textures mapped with the bathymetry. The combination of both datasets allows us to discuss the nature of the volcanic structures and to propose a relative chronology of previous eruptive events in the Horseshoe area. Based on our analyses, we propose the following chronology: (a) the emplacement of a large explosive volcanic cone, the Horseshoe edifice, (b) the later collapse of this edifice that resulted in the formation of an elongated, 2 km wide horseshoe-shaped depression, crosscutting older hummocky lava flows, (c) the development of an E–W eruptive fissure associated with numerous explosive craters, east of the Horseshoe edifice, and (d) late volcanism emanating from the rim of the horseshoe-shaped depression that fed elongated thin lava flows both towards and away from the depression. While all volcanic features mapped at the Horseshoe area were emplaced prior to the 2018 eruption, our study shows that this region has still been volcanically active in the recent past. Our results thus document a complex geological history at small spatial scales involved in the construction of major submarine edifices, and that are controlled by volcano-tectonic processes at larger scales.

This article presents the main lines of soil research carried out in the French ultramarine regions within the framework of the Scientific Interest Group Sol (GIS Sol). This work concerns the programs “French Soil Quality Monitoring Network” (RMQS) and "Soil Inventory, Management and Conservation" (IGCS), which were conducted in the Lesser Antilles, Martinique and Guadeloupe, Reunion and Mayotte, and French Guiana. This work has a particular nature because these territories are subject to various climates in the intertropical area, contrasting soil development conditions on continental basement and volcanic island lithologies.For IGCS program, in a first step, legacy data from 1950s regarding soil distribution in these regions were compiled and saved in digital medium. In a second step, morpho-pedological syntheses were made thanks to these legacy data along with geological and geomorphological data, embedded in a database. These works are illustrated in this article with the case of Guadeloupe.The first campaign of RMQS program in overseas was conducted between 2006 and 2015. 67 sites were sampled. The experimental set-up was made with a few adaptations from the set-up in mainland France, regarding site installation, soil analyses, and soil samples management. Some results of this program are presented and discussed: soil carbon stocks in French Guiana, and contents of trace metals and polycyclic aromatic hydrocarbons in island areas. Lastly, strategic pathways for this program are discussed, in order to improve the monitoring of soil properties in these regions., Cet article présente les axes des travaux pédologiques effectués dans les régions ultramarines françaises dans le cadre du Groupement d’Intérêt Scientifique Sol. Ces travaux concernent les programmes « Réseau de mesures de la qualité des sols » (RMQS) et « Inventaire, Gestion et Conservation des Sols » (IGCS), conduits aux Petites Antilles, Martinique et Guadeloupe, à La Réunion et Mayotte, et en Guyane. Ces travaux revêtent un caractère particulier du fait que les territoires concernés sont soumis à des climats variés dans la bande intertropicale et des conditions de développement des sols contrastées sur des lithologies continentales du socle et insulaires volcaniques.Dans le cadre du programme IGCS, les travaux se sont axés dans un premier temps sur l’inventaire et la sauvegarde numérique des connaissances de la distribution des sols acquises dans ces territoires depuis les années 1950. Dans un second temps, des synthèses morpho-pédologiques ont été réalisées grâce à ces données pédologiques numérisées et intégrées à une base de données, complétées par des données géologiques et géomorphologiques. Ces travaux sont illustrés dans cet article à travers le cas de la Guadeloupe.La première campagne du programme RMQS, qui s’est déroulée entre 2006 et 2015, a porté sur 67 sites dans les mêmes territoires. La mise en place de ce programme en Outre-mer s’est faite avec quelques adaptations par rapport au dispositif mis en place dans l’Hexagone, et qui concernent l’implantation des sites, les analyses de sols réalisées et la gestion des échantillons de sols. Quelques résultats de ce programme sont discutés, concernant les stocks de carbone du sol en Guyane, et les teneurs en éléments traces métalliques et hydrocarbures aromatiques polycycliques dans les territoires insulaires. Enfin, les pistes d’évolution du programme sont discutées, afin d’améliorer le suivi des propriétés des sols dans ces territoires.

This documentary file was produced as part of the research project "Professional integration and vocational construction of adolescents in vocational high schools with disabilities in Mayotte" (named MayMobPro), as part of a call for projects from the International Fund for Applied Research on Disability (FIRAH).; Ce dossier documentaire a été produit dans le cadre de la recherche « Insertion professionnelle et construction vocationnelle des adolescent•e•s en lycée professionnel en situation de handicap à Mayotte » (nommé MayMobPro), dans le cadre d'un appel à projet du Fonds International de la recherche appliquée sur le handicap (FIRAH).

International audience; Mayotte is a French overseas department and one of the 4 islands of the Comoros archipelago in the Indian Ocean, located between Madagascar and the eastern coast of Africa. Malaria, mainly by Plasmodium falciparum, is endemic to the archipelago and remained a major public health problem until recent years. To control and then eliminate the disease, major strategies have been established in Mayotte since 2001. Preventive measures, diagnostic testing, treatment and disease surveillance were introduced or improved.From 2002 to 2021, 4819 autochthonous cases were reported in Mayotte where the annual incidence decreased from 10.3 per 1,000 population in 2002 (1649 cases) to less than 0.01 per 1,000 population in 2020 (2 cases). The incidence has been below 1 per 1,000 population since 2009. In 2013, WHO classified Mayotte as a territory in malaria elimination phase. In 2021, no locally acquired malaria cases were reported on the island. During this period 2002-2021, 1898 imported cases were observed. They mainly came from the Union of Comoros (85.8%), Madagascar (8.6%) and sub-Saharan Africa (5,6%). Since 2017, the annual number of locally acquired cases was less than 10 and decreased steadily (9 cases in 2017, 5 in 2018, 4 in 2019 and 2 in 2020). The distribution of these rare locally acquired cases both in time and space suggests that they were introduced and not indigenous cases. A study of the genotypic profile of the plasmodial strains of these cases observed from 2017 to 2020 (17 cases analysed out of 20 diagnosed) confirms that these were certainly introduced cases related to imported cases from the neighboring Comoros.Malaria indigenous transmission seems to be eliminated in Mayotte, but the island remains under threat of reintroduction via cases imported from neighbouring countries. It is time to develop a local plan to prevent reintroduction and to implement a proactive policy of regional cooperation in the fight against malaria.

International audience; Coral reefs are increasingly in jeopardy due to global changes affecting both reef accretion and bioerosion processes. Bioerosion processes dynamics in dead reef carbonates under various environmental conditions are relatively well understood but only over a short-term limiting projections of coral reef evolution by 2100. It is thus essential to monitor and understand bioerosion processes over the long term. Here we studied the assemblage of traces of microborers in a coral core of a massive Diploastrea sp. from Mayotte, allowing us to explore the variability of its specific composition, distribution, and abundance between 1964 and 2018. Observations of microborer traces were realized under a scanning electron microscope (SEM). The area of coral skeleton sections colonized by microborers (a proxy of their abundance) was estimated based on an innovative machine learning approach. This new method with 93% accuracy allowed analyzing rapidly more than a thousand SEM images. Our results showed an important shift in the trace assemblage composition that occurred in 1985, and a loss of 90% of microborer traces over the last five decades. Our data also showed a strong positive correlation between microborer trace abundance and the coral bulk density, this latter being particularly affected by the interannual variation of temperature and cumulative insolation. Although various combined environmental factors certainly had direct and/or indirect effects on microboring species before and after the breakpoint in 1985, we suggest that rising sea surface temperature, rainfall, and the loss of light over time were the main factors driving the observed trace assemblage change and decline in microborer abundance. In addition, the interannual variability of sea surface temperature and instantaneous maximum wind speed appeared to influence greatly the occurrence of green bands. We thus stress the importance to study more coral cores to confirm the decadal trends observed in the Diploastrea sp. from Mayotte and to better identify the main factors influencing microboring Frontiers in Marine Science frontiersin.org 01

The island of Mayotte, due to its insular position and very uneven relief, is particularly exposed to several types of natural hazards: cyclones, land movements, seismicity, and tsunamis that may be generated by the new submarine volcano located 50 km off the east coast of Mayotte. In addition to these multiple hazards, Mayotte has been undergoing profound socio-spatial changes over the last forty years, in connection with the increase in population due to massive illegal immigration from neighbouring countries, urban sprawl, etc. Some anthropised areas have been built illegally on land that is highly exposed to natural hazards, without respecting urban planning. Due to multiple factors, but mainly of a socio-economic nature, the populations living there are particularly vulnerable and mainly descendants of illegal immigrants. They are accused of all the ills that affect this territory: aggression, rape, theft, degradation of ecosystems, etc. They are in a position of vulnerability and are not allowed to leave the area. They find themselves in a position of rejection by certain mahorais citizens and local authorities. From this point of view, by positioning ourselves in the field of the global vulnerability paradigm, this research aims, in the first instance, to determine the root causes of socio-economic and political vulnerability, and to understand the process of construction of differential vulnerability within the Comorian migrant population. Secondly, the effectiveness of the French risk and crisis management model applied to this overseas department, which has the characteristics of a developing territory with its usual peculiarities (poverty, massive and 'uncontrolled' illegal immigration, anarchic urbanisation, intercommunity tensions, etc.), will be assessed. From there, a critical analysis of official risk management policies and documents will be presented, as well as the results of surveys conducted in the field on the vulnerability of migrants. On the basis of these documents and results, the weaknesses of these public policies in dealing with the foreign and vulnerable population will be demonstrated. Thus, the results of our research (the problem of access to resources, the identification of the root causes of vulnerability with migrants) lead us to propose avenues, solutions, which seem to us to be fair and sustainable in order to reduce vulnerability, poverty, and facilitate access to resources, and to envisage a prospective societal approach to adapting the institutional mechanisms aimed at incorporating migrants into mahorais society; L’île de Mayotte, de par sa position insulaire et son relief très accidenté, est particulièrement exposée à plusieurs types d’aléas naturels : cyclones, mouvements de terrain, sismicité, et tsunamis pouvant être générés par le nouveau volcan sous-marin situé à 50 km au large des côtes est de Mayotte. En plus de ces multiples aléas, Mayotte connaît depuis une quarantaine d’années, de profondes mutations socio-spatiales, en lien avec la hausse de la population due à une immigration clandestine massive venant des pays voisins, un étalement urbain, etc. Certaines zones anthropisées ont été construites illégalement sur des terrains fortement exposés aux aléas naturels, sans respecter les plans d’urbanisme. En raison de facteurs multiples mais pour l’essentiel de nature socioéconomique, les populations qui y vivent sont particulièrement vulnérables et essentiellement issues de l’immigration clandestine. Elles sont accusées de tous les maux qui affectent ce territoire : agressions, viols, vols, dégradations des écosystèmes, etc. Elles se retrouvent dans une position de rejet de la part de certains citoyens mahorais et des autorités locales. Partant de là, en nous positionnant dans le champ du paradigme de la vulnérabilité globale, cette recherche vise, dans un premier temps, à déterminer les causes profondes de vulnérabilités socio-économique et politique, et à comprendre le processus de construction de la vulnérabilité différentielle au sein de la population migrante comorienne. Dans un deuxième temps, il s’agit d’évaluer l’efficacité du modèle de gestion des risques et des crises français appliqué à ce département d’outre-mer qui a les caractéristiques d’un territoire en développement avec ses particularités habituelles (pauvreté, immigration clandestine massive et « incontrôlée », urbanisation anarchique, tensions intercommunautaires, etc.) De là, seront présentés une analyse critiques des politiques et des documents officiels de gestion des risques, mais aussi les résultats d’enquêtes menées sur le terrain et portant sur la vulnérabilité des migrants. Sur la base de ces documents et de ces résultats, il s’agira de démontrer les faiblesses de ces politiques publiques dans leur prise en charge de la population étrangère et vulnérable. Ainsi, les résultats issus de notre recherche (la problématique d’accès aux ressources, l’identification des causes profondes de la vulnérabilité avec les migrants) amènent à proposer des pistes, des solutions, nous semblant justes et pérennes pour réduire la vulnérabilité, la pauvreté, et faciliter l’accès aux ressources et envisager une approche prospective sociétale d’adaptation des dispositifs institutionnels visant à incorporer les migrants dans la société mahoraise.

International audience; Accurate and reliable bathymetric data are needed for a wide diversity of marine research and management applications. Satellite-derived bathymetry represents a time saving method to map large shallow waters of remote regions compared to the current costly in situ measurement techniques. This study aims to create very high-resolution (VHR) bathymetry and habitat mapping in Mayotte island waters (Indian Ocean) by fusing 0.5 m Pleiades-1 passive multispectral imagery and active ICESat-2 LiDAR bathymetry. ICESat-2 georeferenced photons were filtered to remove noise and corrected for water column refraction. The bathymetric point clouds were validated using the French naval hydrographic and oceanographic service Litto3D® dataset and then used to calibrate the multispectral image to produce a digital depth model (DDM). The latter enabled the creation of a digital albedo model used to classify benthic habitats. ICESat-2 provided bathymetry down to 15 m depth with a vertical accuracy of bathymetry estimates reaching 0.89 m. The benthic habitats map produced using the maximum likelihood supervised classification provided an overall accuracy of 96.62%. This study successfully produced a VHR DDM solely from satellite data. Digital models of higher accuracy were further discussed in the light of the recent and near-future launch of higher spectral and spatial resolution satellites.

International audience; The loss of natural habitats is generally associated with a loss of biodiversity that will cause a change in the functioning of ecosystems and consequently in their capacity to provide ecosystem services. As ecosystem engineers, mangrove crabs fulfil key ecological roles in the structure of the mangrove ecosystem through burrowing and in the functioning through nutrient cycling and bioturbation. They are also of societal and economic interest that can be used by the populations. In the West Indian Ocean, there are gaps in knowledge on the identification and distribution of mangrove crab species. This challenges our understanding of the consequences of mangrove erosion on the associated biodiversity. For example, between 1950 and 2016, the mangroves of Mayotte have been affected by a moderate regression of 6%. This loss is likely to impact the distribution of crabs and consequently the structure and functioning of the ecosystem. The objective of this study is to understand the impact of mangrove erosion on the distribution of crabs through an interdisciplinary approach combining methodologies in ecology, human geography and geomorphology.The combination of these methodologies allows access to data at several temporal and spatial scales. The characterisation of erosion rates since 1950 and consequences on sedimentary movements at large temporal and spatial scales will be provided by geomorphology data. The human geography data provides access to a medium temporal scale on the characterisation of the evolution of the distribution of crabs at the scale of the bay over the last decades. At a finer scale, by replacing time by space, the ecology data will ensure a comparison of two zones representing two different instants of the mangrove erosion trajectory.This study focuses on the mangroves of Dapani and Mzouazia, located on the southern coast of Mayotte Island. We focus on the central and sea mangroves because have been in major decline since 1950. The Mzouazia mangrove covers 3 ha, consisting of Sonneratia alba in seaward fringe, followed by a fringe of Rhizophora mucronata. The Dapani mangrove covers 10 ha, is composed of a Sonneratia alba in the seaward fringe, followed by a large Rhizophora mucronata stand in the central mangrove.The methodology used in geomorphology consisted of a diachronic analysis of vertical aerial photographs between 1950 and 2020 in order to characterise the spatial evolution of the mangroves studied over 70 years. Aerial photographs taken by unmanned aerial vehicles were also acquired in order to characterise the surface changes of mangroves in the short-term between 2020 and 2022. Topographic surveys were carried out between 2020 and 2022, in order to characterise the morphology of the coastal profile and its evolution. We also have a series of topographic profiles distributed irregularly between 2005 and 2019. In human geography, we conducted semi-structured interviews with people in villages bordering the mangroves of Mzouazia and Dapani in order to better understand their local ecological knowledge regarding crabs. We targeted people over 15 years old who have been frequenting or regularly visiting the mangrove for several years or people having activities near the mangrove. We asked people about the vernacular names of the crabs present in the mangrove of their village, a recognition criteria, their location, their habitat and about the evolution of their distribution area, quantity and size.The objective of the ecology protocol was to compare the distribution of crab species across the shore, along an eroding and non-eroding mangrove section. For this purpose, two 100 m long transects were deployed per mangrove, starting from the beach ridge, and oriented perpendicular to the coastline. The Point-Centered Quarter Method was used to place 10 sampling points haphazardly along the transects where we measured the following parameters: abundance of crab species, identity of dominant mangrove trees, tree circumference, and grain size. The height on the foreshore is provided by a digital elevation model. Data have been acquired in Mzouazia and those in Dapani will be acquired in the coming weeks.The analysis of aerial photographs shows that these two mangroves have experienced a regression of -64% for Dapani and -15% for Mzouazia since 1950. On the eroding section, the morphological measurements show an accumulation of sand which reflected a significant rise of 0.55 m in the beach ridge from February 2005 to March 2022. The profiles also show a retreat of almost -10m of sediment between 2013 and 2022, reflecting the decrease in height on the foreshore. The sediment analyses performed along the transects show that muddy sediments prevail in the non-eroded sections whereas sandy sediments dominate eroded sections. This can be explained by the presence of trees, which attenuate the wave energy and favour the deposition of fine sediments, whereas in the eroded area, fine sediments are transported away and coarse sediments accumulate on the beach ridge.Preliminary results of the 19 semi-structured interviews conducted in Mzouazia show that the inhabitants are more familiar with Cardisoma carnifex and Scylla serrata, which live at the land and sea ends of the mangrove. They do not seem, however, to perceive the effects of marine erosion on the distribution of crabs. Yet, crab community distributions show a higher species abundance and richness in the non-eroded mangrove sections than in the eroded mangrove sections. Comparison with the data provided by the 18 semi-structured interviews conducted in Dapani and the ongoing study of crab distributions will allow generalising these results. The relative importance of tree presence, grain size, and elevation on the foreshore for crab community composition will also be discussed and confronted to the species used and known by inhabitants.These data provide new information on the distribution of mangrove crabs and on the factors affecting their distributions. These data may raise questions about potential changes in mangrove ecosystem functioning, and the consequences for the ecosystem services provided by eroding mangroves. As such, they will provide predictive data on the distribution of mangrove crabs that will be of interest to stakeholders and scientists. Analysis of the data will identify if environmental memory is being lost with the erosion of the mangrove.

The majority of Earth volcanism takes place in the deep ocean. Deep-sea volcanoes are particularly complicated to study due to their remoteness. Very different methods can be used and their combination can lead to crucial information about submarine volcanoes behavior. In Mayotte, Comoros archipelago, efforts have been made to study and monitor the deep volcanic activity (∼3000 m) currently occurring east of Mayotte through various methods and campaigns on land and at sea. In October 2020, a line of 10 Ocean Bottom Seismometers was deployed during 10 days, leading to a hand-picked catalog of more than a thousand of hydro-acoustic signals, which have been associated with reactions between hot lava and deep cold ocean waters. During the same period, repeated swath bathymetry surveys were performed over an active lava flow field. We compare the time evolution of the hydro-acoustic events locations and bathymetry differences observed between each survey. While bathymetric information gives absolute location of new lava flows, hydro-acoustic events give detailed relative time variations leading to short-term spatial evolution. Bathymetric information thus provides snapshots of the eruptive area evolution at specific times, when hydro-acoustic signals show its continuous evolution. By combining both complementary analyses we are able to clearly define the detailed evolution of the lava flows pattern in the short time period of 10 days. Applied to the data already acquired on Mayotte since 2019, this method could allow us to estimate more precisely the volcano effusion rate and its evolution, giving further insights on the feeding system.

Le Crabier blanc est une espèce d'ardéidé classée « en danger d’extinction » à l’échelle mondiale. La population nicheuse française, composée de plusieurs centaines de couples sur Mayotte, fait l’objet d’un Plan national d’actions. Le Parc naturel marin (PNM) de Mayotte souhaite mettre en place un indicateur des tendances des effectifs nicheurs de crabiers de l’île. Depuis quelques années, ce suivi des colonies nicheuses dans les mangroves est assuré par le GEPOMAY, association ornithologique locale. Il consiste à réaliser des survols par drone de toutes les colonies nicheuses connues, puis à compter les individus et les nids par photo-interprétation des clichés obtenus. Bien que l’utilisation de drones offre un accès à de nombreuses données non mobilisables depuis le sol, on peut pointer certaines limites à cette approche, liées aux technologies et à l’écologie de l’espèce. En effet, la détection des individus ou des nids sur les clichés réalisés par drone n’est pas de 100%, et cette proportion pourrait varier dans le temps et dans l’espace selon plusieurs facteurs tels que la phénologie de l’espèce, son rythme d’activité journalier, l’expérience du photo-interprète, etc. Ces facteurs, s’ils ne sont pas contrôlés, pourraient être à l’origine de biais dans les estimations de tendances des effectifs. Nous avons mis en place une étude-pilote en 2020-2021 afin de répondre à deux principaux objectifs :(i) caractériser les variations d’abondance (comptages) des adultes, juvéniles et nids au cours de la journée et au sein de la saison de reproduction ; (ii) estimer les abondances et probabilités de détection des nids de crabiers par méthodes de CMR à partir des clichés obtenus lors des différentes sessions de survol. Cette étude-pilote nous permettra d’évaluer les forces et faiblesses de l’approche par drone. Nous nous appuyons sur les résultats obtenus pour proposer une stratégie d’échantillonnage temporelle et spatiale pour mesurer les tendances des effectifs en nids actifs et en juvéniles de crabiers blancs sur l’île de Mayotte. Ce document justifie les choix méthodologiques réalisés et propose un cadre pour le recueil, le stockage et l’analyse des données. Il fixe également les moyens logistiques nécessaires à la mise en œuvre du protocole proposé. L’ensemble de ces informations garantit la pérennité de l’étude sur le long terme.L’élaboration de ce protocole s’inscrit dans le cadre d’une coopération entre l’Office Français de la Biodiversité et le Centre d’Ecologie Fonctionnelle et Evolutive. Cette coopération lancée en 2018 vise à mettre en place un appui méthodologique et statistique pour un transfert continu de compétences, de savoirs, de méthodes, vers les gestionnaires des parcs nationaux et des autres aires protégées.

Lorsque Mayotte est cédée à la France en 1841, un vaste chantier de construction s’opère et l’île se dote d’un centre administratif et d’habitations pour les fonctionnaires et colons. L’étude des bâtiments dits de l’ancien Tribunal (construit en 1955) permet non seulement d’appréhender l’organisation de la justice à Mayotte depuis la seconde moitié du xixe siècle, mais également de suivre l’implantation de l’administration française sur l’île, de Dzaoudzi (Petite Terre) à Mamoudzou (Grande Terre). Bien que cet ensemble architectural ne soit plus affecté à sa fonction juridique initiale, l’ancien Tribunal de Mamoudzou conserve une certaine monumentalité sur le front de mer. Il demeure un témoin de l’introduction de modèles-types pour les bâtiments administratifs de la seconde moitié du xxe siècle. Entre conservation du patrimoine bâti et désir de modernité, la réhabilitation et l’appropriation d’un site récemment inscrit au titre des monuments historiques posent les bases d’une réflexion indispensable à Mayotte. When Mayotte was purchased by France in 1841, major works were undertaken on the island to provide central administration and dwellings for civil servants and colonists. Studying the buildings known as "the Old Courthouse" (built in 1955) not only gives an insight into the organisation of justice in Mayotte since the second half of the 19th century, but also makes it possible to follow the establishment of French administration on the island, from Dzaoudzi (Petite Terre) to Mamoudzou (Grande Terre). Although this architectural whole is no longer used for its original legal function, the Old Courthouse of Mamoudzou still remains monumental at the seafront. It stands as a testament to the introduction of architectural prototypes for the administrative buildings in the mid-20th century. Halfway between preservation and the desire for modernity, the question of restoring and re-appropriating a site recently listed as a historic monument (monument historique) calls for some reflection in Mayotte.

At this time, the literature reports only one case of superinfection with Panton-Valentine leukocidin (PVL)-producing Staphylococcus aureus in a patient with severe acute respiratory distress syndrome secondary to coronavirus 2 (SARS-CoV-2) pneumonia. Here we report the first two cases of PVL-producing S. aureus healthcareassociated pneumonia in patients hospitalized for SARS-CoV-2 pneumonia in the Indian Ocean region. The two isolated strains of S. aureus were found to belong to the ST152/t355 clone, a known PVL-producing S. aureus clone that circulates in Africa and is responsible for infections imported into Europe. Our two cases reinforce the hypothesis that SARS-CoV-2 infection favors the occurrence of PVL-producing S. aureus pneumonia. Production of PVL should be searched in patients returning from the Indian Ocean region who present with severe SARS-CoV-2 pneumonia complicated by superinfection with S. aureus even in the case of late onset healthcare-associated pneumonia Dear Editor, Bacterial superinfections in patients with severe acute respiratory distress syndrome secondary to coronavirus 2 (SARS-CoV-2) pneumonia are relatively rare and are often caused by Staphylococcus aureus [1]. At this time, the literature reports only one case of superinfection with Panton-Valentine leukocidin (PVL)-producing S. aureus in a patient with SARS-CoV-2 pneumonia[2]. Here we report the first two cases of PVL-producing S. aureus healthcare-associated pneumonia in patients hospitalized for SARS-CoV-2 pneumonia in the Indian Ocean region.