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Reconnues comme une cause majeure de destruction des récifs coralliens de l'Indo-Pacifique, ces proliférations ont fait l'objet d'un important effort de recherche scientifique mais ont également entraîné la mise en oeuvre d'ambitieux programmes de gestion dans certains pays de la région. En Nouvelle-Calédonie, plusieurs événements de proliférations massives d'acanthasters ont été enregistrés au cours des dernières années mais la stratégie de gestion à adopter face à ce phénomène fait l'objet de débats parmi les acteurs locaux. Cela concerne en particulier, l'adoption ou non de mesures de contrôle des proliférations. C'est dans ce contexte que gestionnaires et experts calédoniens ont été invités à se réunir et à échanger sur ce sujet afin de 1) présenter un état des lieux objectif des connaissances scientifiques disponibles localement et régionalement et 2) établir les tenants et aboutissants en lien avec le suivi du phénomène et la mise en oeuvre d'éventuelles actions de contrôle.

L’ escalade est un sport qui gagne en popularité depuis quelques décennies en Occident. Sa pratique à l’extérieur perturbe la biodiversité associée aux parois rocheuses et aux autres habitats à proximité. Ces habitats hébergent des assemblages d’espèces uniques, mais méconnus en raison de leur accès souvent difficile. Ainsi, la pratique de l’escalade pourrait menacer des populations d’espèces d’intérêt pour la conservation. Cette revue de littérature a pour objectif : 1) de brosser un portrait de la biodiversité associée aux parois, aux talus d’éboulis et aux blocs, en prenant l’Amérique du Nord comme étude de cas ; 2) de synthétiser les connaissances sur les conséquences écologiques de l’escalade ; 3) de documenter les mesures d’atténuation actuelles ; 4) d’identifier les lacunes dans les connaissances actuelles ; 5) de proposer des pistes pour les recherches et les efforts de conservation futurs., In recent decades, climbing has gained in popularity in western countries. Outdoor rock climbing affects the biodiversity associated with cliff faces and adjacent habitats. As these habitats host unique species assemblages that are largely undocumented, primarily because they are difficult to access, climbing could threaten populations of species of conservation interest. This literature review: 1) provides a portrait of the biodiversity associated with cliffs, screes and boulders, using North America as a case study; 2) summarizes the current knowledge about the ecological impacts of rock climbing; 3) documents current mitigation measures; 4) identifies knowledge gaps; 5) suggests avenues for research and conservation efforts.

Le 6 janvier 1994, le barrage de Petit-Saut a fermé ses portes après près de quatre ans de travaux. Le remplissage de la retenue s’est effectué en deux temps. Entre janvier 1994 et début juillet 1994, le niveau s’est élevé de près de 30 m puis, pour des raisons techniques, le remplissage a été arrêté et repris en décembre de la même année. Le remplissage total s’est achevé en juin 1995 lorsque la cote 35 m a été atteinte (fig. 26). Conformément à la législation en vigueur, un débit minimum de...

Entre 1990 et 2002. l’IRD a mené des études approfondies sur les peuplements piscicoles du fleuve Sinnamary en Guyane française, afin d’évaluer les effets du barrage hydroélectrique de Petit-Saut, mis en eau en janvier 1994. Quatre années d’observations avant la construction du barrage et neuf années après ont permis une description détaillée des peuplements de poissons dans le fleuve et une analyse de leur évolution sous l’effet de la perturbation majeure subie par ce bassin tropical. Cet ouvrage constitue une synthèse de ces études. Il est exceptionnel, en milieu tropical, de disposer de données exhaustives concernant les conséquences d’un barrage sur les peuplements de poissons. La prise en compte d’études parallèles sur les autres compartiments de l’écosystème (invertébrés, végétation, chimie des eaux, hydrologie) rend possible une interprétation des mécanismes en jeu dans les transformations, seule à même d'anticiper les changements et d’en limiter les impacts négatifs. Accessible à un large public grâce à une présentation didactique des méthodes scientifiques utilisées, l'ouvrage intéressera également les spécialistes à travers les interprétations des résultats présentés. Il constituera une référence utile dans le cadre d’autres projets de barrage ou d’aménagements similaires en région tropicale.

Fin 1995, la retenue est remplie, la production d’électricité devient totalement opérationnelle. À l’aval, le seuil de ré-oxygénation fonctionne et la qualité de l’eau est satisfaisante. Dans la retenue, tous les arbres noyés sont morts et, progressivement, les branches tombent en commençant par les plus petites, si bien qu’à la fin de la période, seuls les squelettes des arbres persistent. Les seules touches de vert dans ce paysage hivernal sont les épiphytes (orchidées, broméliacées) qui re...

La construction d’un barrage sur un cours d’eau, comme d’ailleurs tout aménagement destiné à améliorer le bien-être de la société en général, est précédée de tout un processus de décision. Celui-ci consiste, d’une part, à évaluer la faisabilité de l’opération et, d’autre part, à tenter de prévoir son bilan coût-bénéfice. En termes économiques, ce bilan est relativement facile à réaliser, mais il n’en est pas de même lorsque l’on y inclut le coût environnemental qui est difficilement chiffrabl...

La construction de barrages n’est pas un phénomène récent. Dès l’Antiquité, des ouvrages ont été élaborés essentiellement à des fins d’irrigation ou de stockage de l’eau (WCD, 2000). Récente, en revanche, est la prolifération de barrages de grande taille observée durant le siècle dernier. À la fin du xxe siècle, on comptait plus de 45 000 grands barrages dans plus de 140 pays (WCD, 2000). Ces ouvrages et les réservoirs qu’ils génèrent, conçus pour favoriser le développement, induisent de prof...

Géographie physique Le bassin du Sinnamary occupe une position centrale dans le système hydrographique guyanais (fig. 3, cf. cahier couleur). Le fleuve prend sa source dans les reliefs peu élevés des massifs centraux de la Guyane à quelque 130 m d’altitude et s’écoule du sud au nord jusqu’à la plaine côtière (fig. 4, cf. cahier couleur). Il s’agit d’un fleuve de moyenne importance avec un bassin de 6 565 km2 et une extension d’environ 250 km. Il n’a que deux affluents de taille significative,...

Les fleuves et rivières tropicaux, du fait de leur grande richesse faunistique, constituent des laboratoires du plus grand intérêt pour l’étude de l’écologie des communautés animales. Il s’agit, d’une part, d’évaluer la biodiversité, dont l’un des indices les plus simples est le nombre d’espèces ou richesse spécifique. Il s’agit, d’autre part, de tenter de comprendre comment de nombreuses espèces coexistent dans un même lieu. Une population (ensemble des individus d’une même espèce habitant d...

La Charte de l'environnement de 2005 pose la nécessité pour les pouvoirs publics de concilier des préoccupations de nature opposées ou différentes portant sur l’utilisation des environnements, dans le cadre du développement durable. Face à ce principe de conciliation nouveau, lors d’une affaire où le juge administratif serait saisi pour examiner un acte autorisant ou interdisant un projet, il lui revient de départager des intérêts de force asymétrique, de tenter de les rapprocher et d’en réussir la conciliation. Les instruments pour parvenir à l’exercice sont peu questionnés. L’un d’eux, mal connu en droit public, est "la capacité de charge". Capable de renseigner la juridiction sur les données environnementales de la zone, et sous conditions d’analyser la résilience des écosystèmes lors de la confrontation avec les opérations de développement et d’exploitation des terrains ou des stocks de ressources naturelles, elle peut faciliter l’exercice juridique de conciliation et assister la décision juridictionnelle.

International audience; El petróleo, "sangre de la tierra", es la principal fuente de energía fósil en el mundo. La Amazonía ecuatoriana, tierra de explotación petrolera y de colonización agrícola, es símbolo de la riqueza natural del planeta pero también un testigo del daño causado por las actividades humanas. En el corazón de este bosque, de su biodiversidad, de sus recursos y de sus habitantes, se teje el hilo de un viaje científico e interdisciplinario. Este libro comparte saberes, conocimientos e imágenes sobre los impactos y riesgos de las actividades petroleras en el medio ambiente, la salud, la sociedad y refleja las condiciones de vida en la Amazonía.; Le pétrole est le « sang de la terre » et la principale source d’énergie fossile au monde. L’Amazonie équatorienne, terre d’exploitation pétrolière et de colonisation agricole, est un symbole des richesses naturelles de la planète mais aussi un témoin des dommages causés par les activités humaines. Au cœur de cette forêt, de sa biodiversité, de ses ressources et de ses habitants, se tisse le fil d’un voyage scientifique et interdisciplinaire. Ce livre partage des savoirs, des connaissances et des images sur les impacts et risques liés aux contaminations pétrolières sur l’environnement, la santé et la société et comment on « vit avec ».

International audience; The Gulf of Gabes is one of the most productive fishery areas in the southern Mediterranean Sea. It is archetypal of an ecosystem in which the effects of fisheries are most pronounced. Demersal trawling is the main fishing activity in the Gulf of Gabes. Life Cycle Assessment (LCA) was applied to assess the environmental performance landing 1 t of seafood with wooden demersal trawlers in the Gulf of Gabes. Impact categories included in the study were abiotic depletion potential (ADP), acidification potential (AP), eutrophication potential (EP), global warming potential (GWP), ozone depletion potential (ODP), photochemical oxidant formation potential (POFP), human toxicity potential (HTP), marine eco-toxicity potential (METP), terrestrial eco-toxicity potential (TETP), land occupation potential (LOP), and total cumulative energy demand (TCED). Demersal trawlers were classified based on their impact intensity. Results showed that 70% of the vessels had relatively low impacts. Impact intensity was proportional to the amount of fuel consumed to land 1 t of seafood. Ships that fished less had the highest impacts per ton, due to lower fishing effort and catch per unit effort. This is likely to typify vessels that target highly valuable species such as shrimp. Onboard vessel activities contributed most to different environmental impacts (AP, EP, GWP and POFP), related to the high energy use of this fishery. Several impacts (ADP, ODP, METP, LOP and TCED) were associated mainly with fuel and lubricating oil production. Therefore, improvements must focus on minimizing fuel consumption. LCA is a valuable tool for assessing how to increase environmental sustainability of demersal trawling and it can help stakeholders identify the main operational issues that require improvement.

The future of West Africa depends on the capacity of its agriculture to ensure the food security of the population, which should double in the next 20 years, while facing up to the new risks resulting from climate warming. Indeed, the changes in temperature and precipitations already operating and that should become more marked will have serious effects on agricultural production and water resources in this part of Africa in the near future. One of the keys to meeting this new challenge is the adaptation of rural societies to climate risks. To gain better knowledge of the potential, processes and barriers, this book analyses recent and ongoing trends in the climate and the environment and examines how rural societies perceive and integrate them: what are the impacts of these changes, what vulnerabilities are there but also what new opportunities do they bring ? How do the populations adapt and what innovations do they implement - while the climate-induced effects interact with the social, political, economic and technical changes that are in motion in Africa ? By associating French and African scientists (climatologists, agronomists, hydrologists, ecologists, demographers, geographers, anthropologists, sociologists and others) in a multidisciplinary approach, the book makes a valuable contribution to better anticipation of climatic risks and the evaluation of African societies to stand up to them.

EABIOMEAGROSUP; De par leur structure tridimensionnelle, leur large gamme de porosité, la diversité de leurs caractéristiques physicochimiques et des conditions microclimatiques, les sols abritent un nombre considérable, parfois inestimable d'organismes. Au sein des agroécosystèmes, les enjeux sont de comprendre les relations entre la plante cultivée et son environnement biophysique incluant les interactions biologiques et les effets de la biodiversité des organismes des sols. L’impact de la faune du sol sur la production primaire peut être vu au travers de leur effet sur les fonctions de (i) recyclage des nutriments, (ii) entretien de la stabilité/structure du sol, (iii) contrôle des bioagresseurs et (iv) support de biodiversité. Ces fonctions écosystémiques sont respectivement associées du point de vue des plantes à (i) leur nutrition, (ii) le milieu physique dans lequel les plantes se développent, (iii) leur santé et (iv) les interactions entre plantes. L’effet de la faune du sol sur chaque fonction peut être expliqué par de nombreux processus et mécanismes qui impliquent l’ensemble des organismes des sols. Ces différents processus sont détaillés dans ce chapitre.

Natural floating objects (e.g., logs) have always been a component of the habitat of tropical tunas. However, the introduction of fish aggregating devices (FADs) modifies this environment. To assess the changes due to the deployment of FADs, we compared the spatial distribution of natural and artificial floating objects (FADs), using data from observers onboard tuna purse seine vessels in the Indian Ocean from December 2006 to December 2008. Although natural objects occur more commonly in waters south of 7 degrees S and FADs are more common in waters north of 7 degrees S, all types of floating objects can be found everywhere. Using different spatial scales (quadrats of size 1 degrees x1 degrees, 2 degrees x2 degrees, 5 degrees x5 degrees, and 10 degrees x10 degrees), we computed the proportion of FADs observed in quadrats without natural objects. The scale of 2 degrees x2 degrees quadrats represented a threshold: distributions of the two types of objects were different at scales smaller than this threshold. The strongest change that has occurred since the introduction of FADs (besides the increased catches) has been the dramatic increase in the total number of floating objects. Since the introduction of FADs, the number of objects has at least doubled everywhere (except in the Mozambique Channel and Chagos) and in some areas (e.g., Somalia area) the multiplication factor has reached as high as 20 or 40. Our study sets the ranges of values of key parameters of the floating object environment, which are crucial in the design of future experimental studies aimed at investigating the impacts of FADs on the ecology of tunas.

Les infrastructures construites sur le fleuve Niger depuis le milieu du XXe siècle ont contribué à la création de nouvelles activités économiques pour le pays. Cependant, l'extension récente de l'Office du Niger soulève des questions sur la place de l'agriculture familiale dans le modèle de développement promu. En outre, les communautés en aval, comme dans le Delta intérieur du Niger, sont affectées par les changements environnementaux liés au développement des infrastructures. L'étude de ces deux zones emblématiques montre la nécessité d'examiner d'une manière plus approfondie la vulnérabilité des populations rurales au moment d'établir les options de politique de développement d'un grand bassin tel que celui du fleuve Niger. (Résumé d'auteur)

Anthropogenic landscape transformation has an important effect on vector-borne pathogen transmission. However, the effects of urbanization on mosquito communities are still only poorly known. Here, we evaluate how land-use characteristics are related to the abundance and community composition of mosquitoes in an area with endemic circulation of numerous mosquito-borne pathogens. We collected 340 829 female mosquitoes belonging to 13 species at 45 localities spatially grouped in 15 trios formed by 1 urban, 1 rural and 1 natural area. Mosquito abundance and species richness were greater in natural and rural areas than in urban areas. Environmental factors including land use, vegetation and hydrological characteristics were related to mosquito abundance and community composition. Given the differing competences of each species in pathogen transmission, these results provide valuable information on the transmission potential of mosquito-borne pathogens that will be of great use in public and animal health management by allowing, for instance, the identification of the priority areas for pathogen surveillance and vector control, This study was funded by project P11-RNM-7038 from the Junta de Andalucía, and project CGL2012-30759 from the Spanish Ministry of Science and Innovation and European Regional Development Fund (FEDER). Funds were also partially provided by EU grant HEALTH.2010.2.3.3-3 project 261391 EuroWestNile and by RNM118 and RNM153 from Junta de Andalucía. Information on remote sensing variables was obtained with the financial support of the project CGL2006-02247/BOS. M.F. and J.M.P. were supported by a FPU grant and a Juan de la Cierva contract, respectively., EUR 1,165 APC fee funded by the EC FP7 Post-Grant Open Access Pilot

Should we be afraid of species introduction ? The question of the introductions of species often suffers from exaggerated fears of security and from hasty generalizations. With the concepts of balance and stability of the ecosystems, a static vision of nature was established. Now it is clear that populations proceed by invasions and successive extinctions, with some cases of spectacular, but cyclical proliferations. The author decides to demonstrate that there is no typical profile of invasive species, but that the resilience of the ecosystem, in its current climatic context, is only in question., La question des introductions d'espèces souffre souvent de la surenchère sécuritaire et de généralisations hâtives. Avec les concepts d'équilibre et de stabilité des écosystèmes, une vision statique de la nature s'est instaurée. Or il est clair que les peuplements procèdent d'invasions et d'extinctions successives, avec quelques cas de proliférations spectaculaires, mais conjoncturelles. L'auteur prend le parti de démontrer qu'il n'existe pas un profil type d'espèce invasive, mais que la résilience de l'écosystème, dans son contexte climatique actuel, est seul en cause., Lévêque Christian. Faut-il avoir peur des introductions d'espèces ?. In: Bulletin mensuel de la Société linnéenne de Lyon, hors-série numéro 2, 2010. Évaluation de la biodiversité rhônalpine. pp. 201-204.

1. While fish-based Indices of Biotic Integrity (IBIs) have been developed for a wide array of lotic systems, equivalent tools have seldom been adapted to the monitoring and assessment of lakes. Major difficulties arise in such work: (i) collecting data that allow statistically robust analyses, (ii) choosing the relevant variables to describe the biotic, environmental and anthropogenic data sets and (iii) assessing the relative importance of the latter two in explaining the former. The aim of the present paper is to produce such an assessment for the fish communities of the lakes of north-east USA. 2. Fish surveys, environmental features and catchment-scale descriptors of human stresses (agricultural and urban land-uses) were collected for 112 natural lakes. 3. Fish metrics, i.e. species richness and percentages of species belonging to reproductive, trophic, and tolerance guilds, were regressed against anthropogenic variables, then against anthropogenic variables and the natural environmental conditions. 4. It was shown that failing to control for the natural environmental conditions in the IBI construction led to selecting metrics (percentage of intolerant species and percentage of omnivorous species) that did not display response to stresses when the environment was controlled for. Moreover, controlling for natural variability of the metrics allowed identifying the impact of agricultural land-use on the percentage of diadromous species. 5. Fish communities appear valuable for the bioassessment of lakes. Appropriate statistical methods have proved that the natural variability in the bioassessment tools could be accounted for, thereby allowing assessments at the scale of multiple basins and ecoregions. This opens new perspectives for the development of IBIs for lentic systems in lake-poor regions, such as southern Europe, and therefore represents a significant contribution to the implementation of the European Water Framework Directive. Copyright © 2007 John Wiley & Sons, Ltd.

The building of a large multipurpose dam is planned at Stiegler's Gorge on the Rufiji River (Tanzania). Both national and local authorities have strongly emphasised the flood control aspect of the dam as they see the Rufiji floods as a major constraint to development. Though it is true that the Rufiji River has a high flow variability at various timescales, the flood perception in local communities differs from this view. The floods, essential for the sustenance of floodplain fertility, and therefore of the farming system, and vital to the productivity of most of the natural resources on which local communities depend, are perceived as a blessing, whilst droughts and the absence of regular flooding are perceived as the main threat. Historically, most of the food shortages in Rufiji District are associated with drought years and the myth of "the flood as a plague" emerged only in the late 1960s during the Ujamaa villagisation policy. The persistence of this myth is favoured by the inadequate assessment of the complexity of the local economies by the District technical staff. This difference in perception of the flood has major implications for development options. Under the current dam design, the alteration of the flooding pattern would have negative consequences for the downstream wetland and forest ecosystems and the flood-associated livelihoods of some 150,000 people. A cost-benefit analysis of flood control measures and a study of a dam design that would maintain the beneficial aspects of flooding should be accorded the highest priority.

L'avenir de l'Afrique de l'Ouest dépend de la capacité de son agriculture à assurer la sécurité alimentaire de sa population, qui devrait doubler en vingt ans, tout en faisant face aux risques nouveaux engendrés par le réchauffement climatique. En effet, les modifications de température et de précipitations déjà à l'oeuvre, et qui devraient s'amplifier, auront dans un futur proche des répercussions importantes sur la production agricole et sur les ressources en eau de cette partie du continent africain. L'adaptation des sociétés rurales aux risques climatiques est une des clés pour relever ce nouveau défi. Pour mieux en connaître le potentiel, les processus et les barrières, cet ouvrage analyse les évolutions récentes et en cours du climat et de l'environnement, et étudie comment les sociétés rurales les perçoivent et les intègrent : quels sont les impacts de ces changements, quelles vulnérabilités mais aussi quelles nouvelles opportunités entraînent-ils ? Comment les populations s'y adaptent-elles, et quelles innovations mettent-elles en oeuvre, alors que les effets induits par le climat interagissent avec les changements sociaux, politiques, économiques et techniques en cours sur le continent ? En associant des chercheurs français et africains (climatologues, agronomes, hydrologues, écologues, démographes, géographes, anthropologues, sociologues...) dans une approche interdisciplinaire, cet ouvrage apporte une contribution précieuse pour mieux anticiper les risques climatiques et évaluer les capacités des sociétés africaines à y faire face.

International audience

Habitat management involving conservative biological control could be a good crop pest management option in poor African countries. A survey was conducted from August 2013 to July 2014 in a rainfed lowland region near Pélébina, northern Benin, in order to characterize spatiotemporal lanscape changes and investigate their influence on the main crop pests and their associated natural enemies. The area was mapped mainly regarding crop fields and fallows. Visual observations were recorded and a database was compiled. Major landscape composition changes were noted between rainy and dry seasons, which affected the presence of both pests and natural enemies. Cereals (rice, maize and sorghum) and cotton were grown in the humid season, and then okra (Abelmoschus esculentus) was the dominant vegetable crop in dry season. These modifications impacted fallow abundance throughout the lowland. Different cotton (e.g. Helicoverpa armigera, Dysdercus sp., Zonocerus variegatus) or rice (e.g. Diopsis Iongicornis, D. apicalis) pests were observed during dry season in okra crops. Dry season surveys of Poaceae in two types of fallows ('humid', 'dry') revealed the presence of very few stem borers: only 0.004% of stems sampled were infested by stem borers, with a mean of 1.13 larvae per stem. Known cereal stem borer species such as Busseola fusca, Coniesta ignefusalis, Sesamia calamistis were not clearly identified among these larvae of their diapausing stage and white color. Unexpected pollinators (Hymenoptera Apidae, genus Braunsapis, Ceratina and Xylocopa) and predators (Crabronidae, genus Dasyproctus) were found in the stems. Sweep-net collection of insects in humid fallows allowed us to describe for the first time in Benin seven Diopsidae species (23% of adults bearing Laboulbeniomycetes ectoparasitic fungi). Some of these species were captured in rice fields during rainy season. Parasitoids (adult Chalcidoidae and Ichneumonoidae) were observed during both seasons but their impact on stem borers was hard to determine, even during the rainy season, due to their low abundance and the difficulty of identification. Predators (Reduviidae, Odonata) were found mainly in humid fallows and rice fields. Regarding our observations, we suggest the presence of alternate host crops such as okra during the dry season for rainy season crop pests. Moreover, fallows also had a real ecological role as a habitat resource for many guilds of insects (pollinators, pests, predators). The management of these landscape components should be the focus of a long-term study with the aim of enhancing pest management of rauny season crop pests.

International audience; no abstract

El auge de la quinua genera un vivo debate sobre sus impactos sociales y ecológicos en el altiplano sur de Bolivia, primer exportador mundial. Un análisis interdisciplinario permite poner en perspectiva los cambios ocurridos desde hace más de 40 años. Sin negar la necesidad de un apoyo a las dinámicas agrarias locales en torno a la quinua, se contestan aquellas afirmaciones que aseguran la insustentabilidad de la producción en el sur de Bolivia., The quinoa boom has provoked a lively debate about its social and ecological impacts in the southern Bolivian highlands, the world's leading export zone. An interdisciplinary analysis puts in perspective those changes seen in the last 40 years. While acknowledging the need for further support to local agrarian dynamics around quinoa production, we challenge affirmations about its unsustainability in southern Bolivia.

Due to the El Nino phenomenon, the 1997-1998 dry season in Roraima (Brazil, Amazonia) was particularly pronounced. Consequently, vegetation fires spread widely and were monitored by many satellites in real time. Satellite images are currently being used to monitor vegetation fires either globally for climate studies or more regionally for impact assessment. After reviewing different satellite data used for impact assessment, this paper focuses on the contribution of SPOT-4's imagery provided by high resolution HRVIR and coarse resolution VEGETATION sensors. These sensors are described with emphasis on those characteristics of potential benefit for forest mapping and fire detection. Early images of Roraima from SPOT-4 are analysed and interpreted to delineate the areas already damaged by fire. VEGETATION images provide a first estimate of damaged areas on a regional scale and an indication of the main ecosystems affected. SPOT HRVIR is used to establish a much more precise classification of various ecosyst...

National audience

International audience; While considered as sustainable and low-cost agricultural amendments, the impacts of organic fertilizers on downstream aquatic microbial communities remain poorly documented. We investigated the quantity and quality of the dissolved organic matter leaching from agricultural soil amended with compost, vermicompost or biochar and assessed their effects on lake microbial communities, in terms of viral and bacterial abundances, community structure and metabolic potential. The addition of compost and vermicompost significantly increased the amount of dissolved organic carbon in the leachate compared to soil alone. Leachates from these additions, either with or without biochar were highly bioavailable to aquatic microbial communities, though reducing the metabolic potential of the community and harboring more specific communities. Although not affecting bacterial richness or taxonomic distributions, the specific addition of biochar affected the original lake bacterial communities resulting in a strongly different community. This could be partly explained by viral burst and converging bacterial abundances throughout the samples. These results underline the necessity to include off-site impacts of agricultural amendments when considering their cascading effect on downstream aquatic ecosystems. This article is protected by copyright. All rights reserved.

21 pages, 9 figures, 4 tables, supporting information https://doi.org/10.1371/journal.pone.0095845, Background: Ecological attributes estimated from food web models have the potential to be indicators of good environmental status given their capabilities to describe redundancy, food web changes, and sensitivity to fishing. They can be used as a baseline to show how they might be modified in the future with human impacts such as climate change, acidification, eutrophication, or overfishing. Methodology: In this study ecological network analysis indicators of 105 marine food web models were tested for variation with traits such as ecosystem type, latitude, ocean basin, depth, size, time period, and exploitation state, whilst also considering structural properties of the models such as number of linkages, number of living functional groups or total number of functional groups as covariate factors. Principal findings: Eight indicators were robust to model construction: relative ascendency; relative overhead; redundancy; total systems throughput (TST); primary production/TST; consumption/TST; export/TST; and total biomass of the community. Large-scale differences were seen in the ecosystems of the Atlantic and Pacific Oceans, with the Western Atlantic being more complex with an increased ability to mitigate impacts, while the Eastern Atlantic showed lower internal complexity. In addition, the Eastern Pacific was less organised than the Eastern Atlantic although both of these systems had increased primary production as eastern boundary current systems. Differences by ecosystem type highlighted coral reefs as having the largest energy flow and total biomass per unit of surface, while lagoons, estuaries, and bays had lower transfer efficiencies and higher recycling. These differences prevailed over time, although some traits changed with fishing intensity. Keystone groups were mainly higher trophic level species with mostly top-down effects, while structural/dominant groups were mainly lower trophic level groups (benthic primary producers such as seagrass and macroalgae, and invertebrates). Keystone groups were prevalent in estuarine or small/shallow systems, and in systems with reduced fishing pressure. Changes to the abundance of key functional groups might have significant implications for the functioning of ecosystems and should be avoided through management. Conclusion/significance: Our results provide additional understanding of patterns of structural and functional indicators in different ecosystems. Ecosystem traits such as type, size, depth, and location need to be accounted for when setting reference levels as these affect absolute values of ecological indicators. Therefore, establishing absolute reference values for ecosystem indicators may not be suitable to the ecosystem-based, precautionary approach. Reference levels for ecosystem indicators should be developed for individual ecosystems or ecosystems with the same typologies (similar location, ecosystem type, etc.) and not benchmarked against all other ecosystems. © 2014 Heymans et al., JH was funded by Knowseas (EUFP7) and Global Environmental Facility (GEF). MC was funded by the European Commission through Marie Curie CIG grant to BIOWEB and the Spanish Research Program ‘‘Ramon y Cajal’’. SL has been partially funded by PERSEUS (EUFP7) and the Flagship Project RITMARE - The Italian Research for the Sea - coordinated by the Italian National Research Council and funded by the Italian Ministry of Education, University and Research within the National Research Program 2011-2013

Historical research is playing an increasingly important role in marine sciences. Historical data are also used in policy making and marine resource management, and have helped to address the issue of shifting baselines for numerous species and ecosystems. Although many important research questions still remain unanswered, tremendous developments in conceptual and methodological approaches are expected to contribute to a comprehensive understanding of the global history of human interactions with life in the seas. Based on our experiences and knowledge from the "History of Marine Animal Populations' project, this paper identifies the emerging research topics for future historical marine research. It elaborates on concepts and tools which are expected to play a major role in answering these questions, and identifies geographical regions which deserve future attention from marine environmental historians and historical ecologists.

While a number of plants, animals, and insects in Madagascar have been called ’invasive’, the topic of invasive species has until recently received less attention here than in other island contexts. Some species, often alien to Madagascar and introduced by humans, have expanded their range rapidly and have had both negative and positive effects on landscapes, on native biodiversity, and on livelihoods. Examples include the prickly pear ( raketa ), the silver wattle ( mimosa ), and, recently, the Asian common toad ( radaka boka ). Building on a conceptual approach to ’invasive species’, this paper emphasizes the importance of inclusive and deliberative site- and population - specific management of invasive species. It analyses three separate concepts commonly used in definitions of invasion: the origin, behaviour, and effects of particular species. It places these concepts in their broader social and ecological context, with particular attention to local perspectives on invasive species. We illustrate these concepts with Malagasy examples and data. The examples demonstrate that while invasions can have dramatic consequences, there can be multiple, often competing, interests as well as site - specific biophysical, environmental, and cultural considerations that need to be taken into account when designing policy and management interventions. We conclude with a number of lessons learned. RESUME Contrairement a la plupart des autres iles, et en depit du quali­ficatif ‘invasif’ rattache depuis longtemps a certaines especes qui s’y sont naturalisees, les reflexions autour de l’approche des especes invasives a Madagascar demeurent recentes. L’opuntia ( Opuntia spp.) figure certes parmi les plus anciens exemples d’especes traites dans la litterature sur les invasions biologiques. Mais ce n’est vraiment qu’avec le retentissement mediatique autour de la detection en 2011 de la presence du crapaud masque ( Duttaphrynus melanostictus ) et la recherche d’une parade appropriee que s’est affirmee la necessite de traiter cette question des especes invasives en tant que telle. Une posture nativiste et uniforme qui ignorerait la specificite des contextes biophysiques et socio - economiques locaux, mais aussi la pluralite des formes d’invasion biologique et des definitions qui s’y rattachent, ne saurait etre privilegiee. L’article montre qu’il s’agit de situer les reflexions dans un contexte insulaire socio - economique dans lequel les especes allogenes tiennent depuis longtemps une large place. Il defend en outre la necessite d’envisager les especes invasives non pas selon une forme de perception unique et autoritariste, mais selon une diversite de points de vue, conforme aux conflits d’interets qui se manifestent parfois, et mettant plutot en avant le caractere exogene des especes invasives, leurs effets (negatifs, mais aussi positifs) sur le milieu, ou leur mode de fonctionnement (dispersion, dominance) dans des contextes specifiques et locaux. Il convient en particulier d’observer qu’aux couts generes par les invasions biologiques peuvent s’ajouter des benefices economiques, et que les impacts ecologiques nefastes peuvent se combiner avec des incidences heureuses, y compris aupres d’especes indigenes en situation critique. En outre, le point de vue des populations humaines, leur connaissance d’especes invasives quotidiennement rencontrees, leur reticence a scinder le vivant en especes indigenes et allogene, mais aussi leur vision pragmatique, ne sauraient etre mesestimes, et moins encore oublies. Enfin, l’article invite a prendre du recul face aux effets rhetoriques lies aux discours conventionnels sur les invasions biologiques, a eviter les amalgames et les generalisations excessives, a tenir compte des contraintes environnementales mais aussi des aspirations socio - economiques des populations locales, et a prendre en compte la diversite des specificites locales, qu’elles soient biophysiques ou sociales. En conclusion, il est sans doute heureux que Madagascar n’ait rejoint que tres recemment la mouvance internationale des reflexions sur les especes invasives : cela lui permet en effet d’etre en mesure de disposer d’une position equilibree, dejouant certains discours catastrophistes, et preferant une approche resolument contextualisee, a l’echelle nationale comme aux echelles regionales.

Shannon, Lynne ... et. al.-- Contribution to the Theme Section ‘Trophodynamics in marine ecology’.-- 26 pages, 4 figures, 8 tables, supplementary material https://doi.org/10.3354/meps10821, © Inter-Research and Fisheries and Oceans Canada 2014 Trophic level (TL)-based indicators have been widely used to examine fishing impacts in aquatic ecosystems and the induced biodiversity changes. However, much debate has ensued regarding discrepancies and challenges arising from the use of landings data from commercial fisheries to calculate TL indicators. Subsequent studies have started to examine survey-based and model-based indicators. In this paper, we undertake an extensive evaluation of a variety of TL indicators across 9 well-studied marine ecosystems by making use of model- as well as surveyand catch-based TL indicators. Using detailed regional information and data on fishing history, fishing intensity, and environmental conditions, we evaluate how well TL indicators are capturing fishing effects at the community level of marine ecosystems. Our results highlight that the differences observed between TL indicator values and trends is dependent on the data source and the TL cut-off point used in the calculations and is not attributable to an intrinsic problem with TLbased indicators. All 3 data sources provide useful information about the structural changes in the ecosystem as a result of fishing, but our results indicate that only model-based indicators represent fishing impacts at the whole ecosystem level, L.J.S. was supported through the South African Research Chair Initiative, funded through the South African Department of Science and Technology (DST) and administered by the South African National Research Foundation (NRF). M.C. was supported by the European Commission through the Marie Curie CIG grant to BIOWEB and the Spanish Research Program Ramon y Cajal. Y.J.S. and M.T. were supported by the French project EMIBIOS (FRB, contract no. APP-SCEN-2010-II). L.J.S. and Y.S. were also funded by the European collaborative project MEECE – Marine Ecosystem Evolution in a Changing Environment – (FP7, contract n°212085). A.B. was supported by Fisheries and Oceans Canada SPERA project ‘Ecosystem indicators for ecosystem monitoring at different scales’ (www.dfo-mpo.gc.ca/science/ecosystem/ projects/detail-eng.asp?pid=21). K.K. was supported by Conservation International and the ‘Sea Around Us’ project, a collaboration between The University of British Columbia and The Pew Charitable Trusts. C.P.L. and C.P. were supported by the EU FP7 project DEVOTES (grant agreement no. 308392), www.devotes-project.eu. C.P.L. was also supported by Defra M1228. This is a contribution to the IndiSeas Working Group, endorsed by IOC-UNESCO (www.iocunesco.org) and the European Network of Excellence Euroceans (www.eur-oceans.eu).

This paper deals with the use of drifting fish aggregating devices (DFADs) in the Indian Ocean and of the potential interest to manage purse seine fisheries through limiting their number. Potential risks associated with a massive use of DFADs are first discussed. Based on new information on the numbers of DFADs released by the French fleet in the 2003-2014 period, this paper estimates the levels and trends of the total numbers of DFADs deployed and active at-sea. It is estimated that the total number of DFADs numbers has been increasing by about 70% since the early 2000s and that they could reach 10,500-14,500 nowadays. A good knowledge of the total numbers of DFADs is urgently needed to better estimate the fishing effort and capacity of purse seine fisheries. Future limitations in the number of DFADs could be a direct and efficient way to reduce fishing effort exerted by purse seiners and their support vessels. Following a precautionary approach, we suggest that IOTC could consider setting a cap on the number of DFADs drifting at-sea and that threshold reference levels could be based on the year 2013, at least to slow down the trend observed in the overall fishing capacity on DFADs. Such measures should be first carefully analysed by an ad hoc IOTC DFAD multidisciplinary working group to ensure their efficient implementation and to allow an improved sustainability of the concerned fisheries.

Pour évaluer les différents changements d’état ou les modifications de fonctionnement du milieu rural induits par les perturbations naturelles, et surtout par les interventions de l’homme, l’observateur a le plus souvent recours à la mesure ou à l’évaluation de simples paramètres, attributs et caractéristiques du système écologique étudié, mais aussi à l’utilisation d’indices complexes calculés à partir de paramètres élémentaires. Cet ensemble est désigné sous le vocable général d’indicateurs...

International audience

Este estudo investigou os bancos de sementes em pastagens implantadas na região de Manaus (Amazonas, Amazônia Central). Em quatro pastagens, foram coletadas 20 amostras de solo de 15 x 15 cm na profundidade de 0 cm a 5 cm e 6 amostras nas profundidades de 5 cm a 10 cm e 10 a 30 cm. Para a contagem e identificação das sementes utilizou-se o método de emergência de plântulas em casa de vegetação. As plântulas foram identificadas por morfotipo e, quando possível, até o nível de espécie. O acompanhamento foi feito durante nove meses. Verificou-se a existência de diferença significativa entre as densidades de sementes das quatro pastagens, variando de 304 a 6153 sementes por metro quadrado, na profundidade de 0 a 5 cm, o que mostra uma alta variação entre as áreas. O número de espécies variou de 17 a 27 na camada superficial. Os bancos de sementes apresentaram-se constituídos predominantemente por herbáceas e espécies lenhosas pioneiras, características de ambientes perturbados. A sucessão vegetal que se desenvolverá necessitará de um intervalo de tempo maior para apresentar estratos arbustivos-arbóreos com maior importância e a floresta será, provavelmente, bem menos heterogênea que a original.

Le symposium international "Le poisson et son habitat" a permis une rencontre entre deux communautés de scientifiques travaillant soit à l'échelle régionale, soit à l'échelle locale. Ce fut l'occasion de synthèses régionales originales et de comparaison intercontinentales des peuplements de poisson. Beaucoup de précisions ont été produites sur l'habitat ontogénétique des poissons et des salmonidés en particulier. Les approches modélisatrices de l'habitat s'enrichissent de nouvelles options de description du compartiment physique de nouveaux modèles d'habitat et bénéficient désormais d'un certain retour d'expérience qui profitera aux actions de préservation et de restauration des milieux aquatiques. La réalisation d'une réelle gestion intégrée de ces milieux passera par la maîtrise théorique et pratique de ces différentes échelles et par un investissement de recherche équilibré entre physique et biologique. (Résumé d'auteur)