Éditeur(s) : Elsevier
Résumé : Sea cruises were conducted for 57 days over 16 months to characterise pelagic fish aggregations around 2 moored fish aggregating devices (FADs) in Martinique (Lesser Antilles). Echosounder surveys run in a star pattern were used in conjunction with obliquely beamed sonar observations. An echo-integration-by-shoal algorithm was implemented to isolate pelagic fish shoals from sound scattering layers and to compute mean morphometric, positional and density parameters. Tree regressions were used to select and classify pelagic fish Target Strengths (TS), with reference to their spatial and temporal characteristics. The main type of pelagic fish aggregation was a large sub-surface aggregation. It was observed during all daytime periods within a radius of 400 m of the FAD. A smaller type of aggregation was observed closer to the surface and to the FAD in 65% of daytime periods. Large scattered fish were observed in 16% of daytime periods. At night, a medium-sized aggregation was detected in the sub-surface in 75% of night-time periods. The sizes of the fish inside the aggregations (determined from TS values) were lower in the small near-surface aggregation than in the large sub-surface aggregation. Mean packing densities of sub-surface medium fish and near-surface small fish aggregations (determined from TS and shoal acoustic density) were respectively 0.2 fish per m3 and 1.3 fish per m3. The acoustic methodology and results are discussed with reference to the characteristics and performance of the echosounder and to the spatial structure of pelagic fish aggregations around moored FADs in Martinique.
Fisheries Research (0165-7836) (Elsevier), 2006-06 , Vol. 82 , N. 1-3 , P. 162-175

Droits : Elsevier 2006
http://archimer.ifremer.fr/doc/2006/publication-1734.pdf
DOI:10.1016/j.fishres.2006.06.025
http://archimer.ifremer.fr/doc/00000/1734/

Éditeur(s) : HAL CCSD Wiley
Résumé : 1. A recent article published by Toledo (2011b) investigates the effects of spatial variations in climate and soil, and of logging disturbance, on tree and forest growth in Bolivia. It concludes that climate is the strongest driver of tree and forest growth and that climate change may therefore have large consequences for forest productivity and carbon sequestration. However, serious methodological and conceptual discrepancies have been found that challenge these conclusions.[br/] 2. Because of an errant coding of time after logging in the regression analysis, and because floristic changes induced by logging could not be incorporated into the analysis, the effect of logging on the average diameter growth is likely to have been strongly underestimated.[br/] 3. Basal area growth was improperly calculated as basal area change, and it displayed surprisingly high values, even among unlogged plots. We hypothesize that either these plots may be actually located in secondary forests recovering from past logging, or measurement biases may have hampered the data set.[br/] 4. Regardless of climategrowth relationships established across these plots, any inference concerning the potential effects of climate change on forest growth would require a specific quantitative assessment.[br/] 5. Synthesis. It is critical to re-assess the relative weight of climate and logging disturbance as driving factors of tree and forest growth, and to find an explanation for the very high basal area increment reported among the unlogged plots. We provide specific recommendations for further analyses of this and similar data sets.
ISSN: 0022-0477

hal-01032432
https://hal.archives-ouvertes.fr/hal-01032432
DOI : 10.1111/j.1365-2745.2011.01895.x

Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
Background: Access to health care is a global public problem. In French Guiana, there exists social inequalities which are specially marked amongst immigrants who make up a third of the population. Health care inequalities are prevalent. The objective of this study was to determine factors associated with why health care amongst the poor population of Cayenne was renounced.Study design The study was cross sectional. It focused on knowledge, attitudes, practices and beliefs of the population living in poor neighborhoods of the Cayenne area. Methods: Populations coming at the Red Cross mobile screening unit in poor urban areas of Cayenne were surveyed from July 2013 to June 2014. Structured questionnaires consisted of 93 questions. Written informed consent was requested at the beginning of the questionnaire. The predictors for renouncing medical care were determined using logistic regression models and tree analysis. Results: Twenty percent of persons had renounced care. Logistic regression showed that renouncement of health care was negatively associated with having no regular physician Adjusted Odds Ratio (AOR)=0.43 (95%CI=0.24-0.79) and positively associated with being embarrassed to ask certain questions AOR=6.81 (95%CI=3.98-11.65) and having been previously refused health care by a doctor AOR=3.08 (95%CI=1.43-6.65) . Tree analysis also showed that three of these variables were linked to renouncement, with feeling shy to ask certain questions as the first branching.Conclusion: Although most people felt it was easy to see a doctor, one in five had renounced health care. The variables identified by the models suggest vulnerable persons generally had previous negative encounters with the health system and felt unwanted or non eligible for healthcare. Health care mediation and welcoming staff may be simple solutions to the above problems which were underscored in our observations.
ISSN: 1472-6963

hal-01288656
https://hal.archives-ouvertes.fr/hal-01288656
https://hal.archives-ouvertes.fr/hal-01288656/document
https://hal.archives-ouvertes.fr/hal-01288656/file/Predictive%20factors%20for%20renouncing%20to%20care%20in%20FG.pdf
PUBMEDCENTRAL : PMC4731954

Éditeur(s) : HAL CCSD Botanical Society of America
Résumé :  
Tree buckling risk (actual height/critical buckling height) is an important biomechanical trait of plant growth strategies, and one that contributes to species coexistence. To estimate the diversity of this trait among wide samples, a method that minimizes damage to the plants is necessary. On the basis of the rarely used, complete version of Greenhill's model (1881, Proceedings of the Cambridge Philosophical Society 4(2): 65-73), we precisely measured all the necessary parameters on a sample of 236 saplings of 16 species. Then, using sensitivity (variance) analysis, regressions between successive models for risk factors and species ranks and the use of these models on samples of self- and nonself-supporting saplings, we tested different degrees of simplification up to the most simple and widely used formula that assumes that the tree is a cylindrical homogeneous pole. The size factor had the greatest effect on buckling risk, followed by the form factor and the modulus of elasticity of the wood. Therefore, estimates of buckling risk must consider not only the wood properties but especially the form factor. Finally, we proposed a simple but accurate method of assessing tree buckling risk that is applicable to a wide range of samples and that requires mostly nondestructive measurements.
ISSN: 0002-9122

hal-01032059
https://hal.archives-ouvertes.fr/hal-01032059

Éditeur(s) : HAL CCSD Wiley
Résumé : The extent of gene dispersal is a fundamental factor of the population and evolutionary dynamics of tropical tree species, but directly monitoring seed and pollen movement is a difficult task. However, indirect estimates of historical gene dispersal can be obtained from the fine-scale spatial genetic structure of populations at drift-dispersal equilibrium. Using an approach that is based on the slope of the regression of pairwise kinship coefficients on spatial distance and estimates of the effective population density, we compare indirect gene dispersal estimates of sympatric populations of 10 tropical tree species. We re-analysed 26 data sets consisting of mapped allozyme, SSR (simple sequence repeat), RAPD (random amplified polymorphic DNA) or AFLP (amplified fragment length polymorphism) genotypes from two rainforest sites in French Guiana. Gene dispersal estimates were obtained for at least one marker in each species, although the estimation procedure failed under insufficient marker polymorphism, limited sample size, or inappropriate sampling area. Estimates generally suffered low precision and were affected by assumptions regarding the effective population density. Averaging estimates over data sets, the extent of gene dispersal ranged from 150 m to 1200 m according to species. Smaller gene dispersal estimates were obtained in species with heavy diaspores, which are presumably not well dispersed, and in populations with high local adult density. We suggest that limited seed dispersal could indirectly limit effective pollen dispersal by creating higher local tree densities, thereby increasing the positive correlation between pollen and seed dispersal distances. We discuss the potential and limitations of our indirect estimation procedure and suggest guidelines for future studies
ISSN: 0962-1083

hal-01031603
https://hal.archives-ouvertes.fr/hal-01031603
DOI : 10.1111/j.1365-294X.2005.02785.x

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Decreasing growth rate (Feeley et al., 2007) and large die-back due to drought (Phillips et al., 2009) suggest that tropical forests are suffering recent climate changes. Forest vulnerability to external factors (e.g. air pollution, acid rain) is widely studied in northern countries, while only a few attempts have investigated crown integrity in the Tropics. The method needs to be generic enough to account for the large number of species and crown shapes encountered in tropical forests. In the present study, we developed and tested a novel field method that estimates crown fragmentation (main branch mortality (MB) and secondary branch mortality (SB)), liana infestation (LI) and crown position (CP) in the canopy. The relationship between crown fragmentation and annual growth rate (agr) was investigated through multiple regression. Six out of eight canopy tree species showed significant growth decline with increasing crown fragmentation. Higher probability of death was also found in trees with severe crown fragmentation. The capacity of such crown assessment to depict tree vitality in a forest stand is discussed along with potential applications in both forest science and management
ISSN: 0378-1127

halsde-00611465
https://hal.archives-ouvertes.fr/halsde-00611465
DOI : 10.1016/j.foreco.2010.10.025

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Fish mucus has important biological and ecologicalroles such as defense against fish pathogens andchemical mediation among several species. A non-targetedliquid chromatography–mass spectrometry metabolomicapproach was developed to study gill mucus of eight butterflyfishspecies in Moorea (French Polynesia), and theinfluence of several fish traits (geographic site and reefhabitat, species taxonomy, phylogeny, diet and parasitismlevels) on the metabolic variability was investigated. Abiphasic extraction yielding two fractions (polar and apolar)was used. Fish diet (obligate corallivorous, facultativecorallivorous or omnivorous) arose as the main driver ofthe metabolic differences in the gill mucus in both fractions,accounting for 23% of the observed metabolic variabilityin the apolar fraction and 13% in the polar fraction.A partial least squares discriminant analysis allowed us toidentify the metabolites (variable important in projection,VIP) driving the differences between fish with differentdiets (obligate corallivores, facultative corallivores andomnivorous). Using accurate mass data and fragmentationdata, we identified some of these VIP as glycerophosphocholines,ceramides and fatty acids. Level of monogeneangill parasites was the second most important factor shapingthe gill mucus metabolome, and it explained 10% of themetabolic variability in the polar fraction and 5% in theapolar fraction. A multiple regression tree revealed that themetabolic variability due to parasitism in the polar fractionwas mainly due to differences between non-parasitized andparasitized fish. Phylogeny and butterflyfish species werefactors contributing significantly to the metabolic variabilityof the apolar fraction (10 and 3%, respectively) buthad a less pronounced effect in the polar fraction. Finally,geographic site and reef habitat of butterflyfish species didnot influence the gill mucus metabolome of butterflyfishes.
ISSN: 0722-4028

hal-01563312
https://hal-univ-perp.archives-ouvertes.fr/hal-01563312
DOI : 10.1007/s00338-017-1554-0

Éditeur(s) : Elsevier
Résumé : The discovery of deep-sea hydrothermal vent fauna, kilometres deep in the oceans, is a great achievement of 20th-century marine biology. The deep-sea hydrothermal food web does not directly depend on the sun's energy. Vent communities rely primarily on trophic associations between chemoautotrophic bacteria and consumers A small. number of endemic taxa are adapted to the inhospitable vent environments that are distributed along ridge crests. Where these vent communities originated and how they dispersed are among the important questions ecologists must answer. Here, by statistical analysis of the most comprehensive database ever assembled about deep-sea hydrothermal fauna, we delineate six major hydrothermal provinces in the world ocean and identify seven possible dispersal pathways between adjacent provinces. Our model suggests that the East-Pacific Rise may have played a pivotal role as a centre of dispersal for the hydrothermal fauna. Our data-driven conclusion will have to be tested by phylogenetic studies and completed by surveys of less-explored fields.
Deep Sea Research Part I: Oceanographic Research Papers (0967-0637) (Elsevier), 2009-08 , Vol. 56 , N. 8 , P. 1371-1378

Droits : 2009 Elsevier Ltd All rights reserved.
http://archimer.ifremer.fr/doc/2009/publication-6936.pdf
http://archimer.ifremer.fr/doc/2009/sup-6936.xls
DOI:10.1016/j.dsr.2009.01.009
http://archimer.ifremer.fr/doc/00000/6936/

Éditeur(s) : HAL CCSD
Résumé : International audience
The aboveground biomass density (AGBD) or aboveground carbon density is mapped for the rainforest of the Basse-Terre Island (Guadeloupe, French West Indies). This mapping is the first devoted to the rainforest of the Lesser Antilles.Mapping AGBD needs the successive realization of two steps. At first, AGBD was estimated in studied forest plots where trees were individually measured; secondly these local estimations were extended through multiple regression including remote sensing LiDAR measurements.Due to the structural specificity of the Caribbean-islands forests, applying general allometry relationship overestimates tree above-ground biomass. Yet we take advantage of pantropical database (Chave et al. 2014) by adopting a suitable statistical procedure: bayesian mixed decision rule.Despite the reduced canopy height, generally less than 35 m, Caribbean lowland rainforests have a high biomass, in every respect comparable to that of continental lowland forests. Such peculiarity is achieved through increased tree density that compensate for lower canopy height.
CAS
Deshaies, Guadeloupe

hal-01514241
https://hal.archives-ouvertes.fr/hal-01514241

Résumé : L'agriculture actuelle est impliquée dans de multiples problématiques environnementales, sociales et économiques, aux échelles locales et globales. En agronomie, de nombreux travaux à l'échelle du champ et de l'exploitation visent aujourd'hui à concevoir des systèmes de culture et des systèmes de production en lien avec ces problématiques. En revanche, peu de travaux portent sur la conception et l'évaluation de systèmes agricoles à l'échelle du territoire, alors que cette échelle apparaît pourtant incontournable pour faire face à des enjeux de développement durable. Pour combler ce manque, nous proposons un ensemble méthodologique permettant i) de simuler les conséquences de scénarios de politiques agricoles sur les choix d'assolement des agriculteurs, décrits individuellement, en modélisant l'évolution de leurs système de production et ii) d'évaluer l'impact de ces changements d'assolements à l'échelle du territoire, à l'aide d'indicateurs qui apportent de l'information spatiale sur la contribution de l'agriculture au développement durable. L'ensemble méthodologique proposé débute par la construction d'une typologie des exploitations agricoles du territoire sur la base de la similarité de leur assolement. Parallèlement, l'adaptation d'indicateurs à l'échelle du territoire permet d'évaluer les impacts des externalités des systèmes de culture en mobilisant des procédures de changements d'échelles. Un modèle bioéconomique générique, multi-échelle, spatialement explicite, appelé MOSAICA, qui utilise la typologie et les indicateurs d'impact de l'agriculture à l'échelle régionale, est créé pour produire des mosaïques de systèmes de culture et évalue leur contribution au développement durable du territoire. Ce modèle, couplé à un itinéraire de définition de scénarios exploratoires et normatifs permet de tester l'impact de différents types de leviers agronomiques, socio-économiques, environnementaux, organisationnels et techniques sur les choix des exploitants et in fine sur la contribution de la mosaïque de systèmes de culture au développement durable du territoire. Nous avons appliqué cet ensemble méthodologique à la conception de scénarios de développement agricoles durables en Guadeloupe. Nous avons dans un premier temps développé une typologie des systèmes de production comprenant huit types distincts et relevant de processus décisionnel différents. Puis nous avons adapté à l'échelle du territoire 19 indicateurs pour l'évaluation des mosaïques de systèmes de culture. L’évaluation de la mosaïque actuelle nous a permis de repérer de faibles niveaux de contribution aux enjeux d’autonomie alimentaire et énergétique. Différents scénarios normatifs et exploratoires intégrant des leviers de changement de la mosaïque ont été testés avec MOSAICA. Les évaluations réalisées nous ont permis d'identifier que des leviers agronomiques comme le développement du maraîchage sans intrants chimiques et des leviers sociaux comme la formation de main-d'oeuvre supplémentaire permettraient d'améliorer la contribution de l’agriculture au développement durable du territoire Guadeloupéen. La modélisation mécaniste de l’évolution du territoire agricole permet d'intégrer des connaissances sur la localisation, les performances, les impacts des systèmes de culture et sur les processus décisionnels des exploitants régissant l’orientation productive et le fonctionnement des exploitations. Cette démarche permet de visualiser les changements de système de culture et leurs impacts de manière spatialement explicite, ce qui permet de générer des connaissances sur les leviers susceptibles de faire évoluer positivement l'agriculture du territoire. La démarche et les outils mis en oeuvre sont donc particulièrement utiles pour l'aide à la décision publique pour améliorer la durabilité de l'agriculture dans son ensemble.
Current agricultural systems are responsible for many different environmental, social and economic issues at both local and global scales. Agricultural sciences have contributed to the design of several methods at the farm and field scale in order to prototype cropping systems and farming systems to address these issues. However, few methods have been designed at the regional scale, while this scale seems to be essential in order to address these issues. In order to fill this gap, we here propose a new methodological framework for i) simulating the consequences of policy changes on farmer's cropping plan, described individually, by modeling the evolution of farming systems and to ii) assess the impacts of cropping system changes at the regional scale, with a set of indicators that generate spatially explicit information on the contribution of agriculture to sustainable development. The methodological framework starts with the design of a farm typology over the territory based on the similarity of farmer's crop acreages. In parallel, a set of indicators is adapted to the landscape scale in order to assess the impacts of cropping system externalities by integrating a set of scale change procedures. A generic, multi-scale, spatially explicit bioeconomic model called MOSAICA, which uses the farm typology and the indicators, is created for generating cropping system mosaics and assessing their contribution to sustainable development. This model coupled to a scenario approach composed of exploratory and normative scenarios can simulate the impact of several types of agronomic, socio-economic, environmental, organizational and technical levers of change on the farmer's choices in terms of cropping systems and in fine the impacts of new cropping system mosaics on the contribution to sustainable development of territories. We applied this methodological framework for building scenarios of sustainable agricultural development in Guadeloupe. We first developed a typology of farming systems encompassing eight types of farming systems that revealed several different farmer's decision processes. Then, we developed 19 indicators to assess cropping system mosaics. The assessment of the current cropping system mosaic showed low levels of response of the current mosaic to economic and social issues especially the food and energy self-sufficiency. Different normative and exploratory scenarios integrating levers of change have been simulated with MOSAICA. The assessment of cropping system mosaics from these scenarios highlighted the positive effect of agronomic levers of change such as organic crop-gardening and social levers such as the vocational training of supplementary workforce for improving the contribution of agriculture to sustainable development of the guadeloupean territory. The mechanistic modeling of the agricultural territory allows us to integrate a wide range of knowledge on the location of cropping systems, their levels of performance , their impacts and the decision process of farmer's that drive the farming system characteristics and the farm functioning. This methodological framework helps visualize the cropping system changes at the regional scale and their associated impacts at the landscape scale which is helpful in order to produce knowledge on the levers of change that can improve the response of local agriculture to local and global issues. The framework and tools designed are particularly useful for decision-aid on the future levels of contribution of agriculture to sustainable development.

http://www.theses.fr/2015AGUY0823/document

Éditeur(s) : HAL CCSD Ecological Society of America
Résumé : Herbivores are often implicated in the generation of the extraordinarily diverse tropical flora. One hypothesis linking enemies to plant diversification posits that the evolution of novel defenses allows plants to escape their enemies and expand their ranges. When range expansion involves entering a new habitat type, this could accelerate defense evolution if habitats contain different assemblages of herbivores and/or divergent resource availabilities that affect plant defense allocation. We evaluated this hypothesis by investigating two sister habitat specialist ecotypes of Protium subserratum (Burseraceae), a common Amazonian tree that occurs in white-sand and terra firme forests. We collected insect herbivores feeding on the plants, assessed whether growth differences between habitats were genetically based using a reciprocal transplant experiment, and sampled multiple populations of both lineages for defense chemistry. Protium subserratum plants were attacked mainly by chrysomelid beetles and cicadellid hemipterans. Assemblages of insect herbivores were dissimilar between populations of ecotypes from different habitats, as well as from the same habitat 100 km distant. Populations from terra firme habitats grew significantly faster than white-sand populations; they were taller, produced more leaf area, and had more chlorophyll. White-sand populations expressed more dry mass of secondary compounds and accumulated more flavone glycosides and oxidized terpenes, whereas terra firme populations produced a coumaroylquinic acid that was absent from white-sand populations. We interpret these results as strong evidence that herbivores and resource availability select for divergent types and amounts of defense investment in white-sand and terra firme lineages of Protium subserratum, which may contribute to habitat-mediated speciation in these trees.
ISSN: 0012-9658

hal-01032403
https://hal.archives-ouvertes.fr/hal-01032403
DOI : 10.1890/12-1920.1