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Auteur (up) Authier, M.; Saraux, C.; Péron, C. doi  openurl
  Titre Variable selection and accurate predictions in habitat modelling: a shrinkage approach Type Article scientifique
  Année 2017 Publication Revue Abrégée Ecography  
  Volume 40 Numéro 4 Pages 549-560  
  Mots-Clés account; distributional data; Ecology; indian-ocean; inference; Mediterranean Sea; regression methods; small pelagic fish; spatial autocorrelation; species distribution models  
  Résumé Habitat modelling is increasingly relevant in biodiversity and conservation studies. A typical application is to predict potential zones of specific conservation interest. With many environmental covariates, a large number of models can he investigated but multi-model inference may become impractical. Shrinkage regression overcomes this issue by dealing with the identification and accurate estimation of effect size for prediction. In a Bayesian framework we investigated the use of a shrinkage prior, the Horseshoe, for variable selection in spatial generalized linear models (GLM). As study cases, we considered 5 datasets on small pelagic fish abundance in the Gulf of Lion (Mediterranean Sea, France) and 9 environmental inputs. We compared the predictive performances of a simple kriging model, a full spatial GLM model with independent normal priors for regression coefficients, a full spatial GLM model with a Horseshoe prior for regression coefficients and 2 zero-inflated models (spatial and non-spatial) with a Horseshoe prior. Predictive performances were evaluated by cross validation on a hold-out subset of the data: models with a Horseshoe prior performed best, and the full model with independent normal priors worst. With an increasing number of inputs, extrapolation quickly became pervasive as we tried to predict from novel combinations of covariate values. By shrinking regression coefficients with a Horseshoe prior, only one model needed to be fitted to the data in order to obtain reasonable and accurate predictions, including extrapolations.  
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  Langue English Langue du Résumé Titre Original  
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  Volume de collection Numéro de collection Edition  
  ISSN 0906-7590 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2130  
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Auteur (up) Ba, A.; Schmidt, J.; Deme, M.; Lancker, K.; Chaboud, C.; Cury, P.; Thiao, D.; Diouf, M.; Brehmer, P. doi  openurl
  Titre Profitability and economic drivers of small pelagic fisheries in West Africa: A twenty year perspective Type Article scientifique
  Année 2017 Publication Revue Abrégée Mar. Pol.  
  Volume 76 Numéro Pages 152-158  
  Mots-Clés Income; management; Senegal; small pelagic fish; Small scale fisheries  
  Résumé Small pelagics are the main fish resource in North West Africa. In Senegal, these are mainly sardinellas (Sardinella aurita and S. maderensis) and bonga shad (Ethmalosa fimbriata). The fisheries, mainly encircling gillnets and purse seines, are predominantly performed by artisanal fishers and are of great importance for the Senegalese economy and for food security in the region. However, in recent years, the main conditions for these fisheries have changed and recent observations have shown strong declines in profit. An analysis over the last twenty years (1993-2013) show that the fisheries lost profit between 65% and 100% while operating costs increased by 25% and 90%, for encircling gillnet and purse seine, respectively. While the fuel price dominates as determining factor during the survey period, important other drivers during the last five years were a decrease in fish biomass and an increase in fishing effort.  
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  Volume de collection Numéro de collection Edition  
  ISSN 0308-597x ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2089  
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Auteur (up) Badji, L.B.; Tiedemann, M.; Fock, H.O.; Ndiaye, P.; Jouffre, D. url  openurl
  Titre Horizontal distribution of dominant pelagic fish eggs in West African waters Type Article scientifique
  Année 2017 Publication Revue Abrégée International Journal of Fisheries and Aquatic Studies  
  Volume 5 Numéro 6 Pages 340-348  
  Mots-Clés  
  Résumé Small pelagic fishes constitute a major fisheries resource along the coast of Western Africa.  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2320  
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Auteur (up) Bakker, J.; Wangensteen, O.S.; Chapman, D.D.; Boussarie, G.; Buddo, D.; Guttridge, T.L.; Hertler, H.; Mouillot, D.; Vigliola, L.; Mariani, S. doi  openurl
  Titre Environmental DNA reveals tropical shark diversity in contrasting levels of anthropogenic impact Type Article scientifique
  Année 2017 Publication Revue Abrégée Sci Rep  
  Volume 7 Numéro Pages 16886  
  Mots-Clés management; ecosystem; conservation; fish communities; rays; populations; collapse; aquatic biodiversity; coral-reef fisheries; wilderness  
  Résumé Sharks are charismatic predators that play a key role in most marine food webs. Their demonstrated vulnerability to exploitation has recently turned them into flagship species in ocean conservation. Yet, the assessment and monitoring of the distribution and abundance of such mobile species in marine environments remain challenging, often invasive and resource-intensive. Here we pilot a novel, rapid and non-invasive environmental DNA (eDNA) metabarcoding approach specifically targeted to infer shark presence, diversity and eDNA read abundance in tropical habitats. We identified at least 21 shark species, from both Caribbean and Pacific Coral Sea water samples, whose geographical patterns of diversity and read abundance coincide with geographical differences in levels of anthropogenic pressure and conservation effort. We demonstrate that eDNA metabarcoding can be effectively employed to study shark diversity. Further developments in this field have the potential to drastically enhance our ability to assess and monitor elusive oceanic predators, and lead to improved conservation strategies.  
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  Volume de collection Numéro de collection Edition  
  ISSN 2045-2322 ISBN Médium  
  Région Expédition Conférence  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2244  
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Auteur (up) Barnagaud, J.-Y.; Kissling, W.D.; Tsirogiannis, C.; Fisikopoulos, V.; Villeger, S.; Sekercioglu, C.H.; Svenning, J.-C. doi  openurl
  Titre Biogeographical, environmental and anthropogenic determinants of global patterns in bird taxonomic and trait turnover Type Article scientifique
  Année 2017 Publication Revue Abrégée Glob. Ecol. Biogeogr.  
  Volume 26 Numéro 10 Pages 1190-1200  
  Mots-Clés Anthropocene; Beta diversity; Beta-diversity; biogeographical legacies; biotic homogenization; climate changes; community; components; dispersal; functional diversity; functional diversity; life-history traits; mammal assemblages; net primary production; regional assemblages; specialization; species richness  
  Résumé AimTo assess contemporary and historical determinants of taxonomic and ecological trait turnover in birds worldwide. We tested whether taxonomic and trait turnover (1) are structured by regional bioclimatic conditions, (2) increase in relationship with topographic heterogeneity and environmental turnover and change according to current and historical environmental conditions, and (3) decrease with human impact. Major TaxaBirds. LocationGlobal. MethodsWe used computationally efficient algorithms to map the taxonomic and trait turnover of 8,040 terrestrial bird assemblages worldwide, based on a grid with 110km x 110 km resolution overlaid on the extent-of-occurrence maps of 7,964 bird species, and nine ecological traits reflecting six key aspects of bird ecology (diet, habitat use, thermal preference, migration, dispersal and body size). We used quantile regression and model selection to quantify the influence of biomes, environment (temperature, precipitation, altitudinal range, net primary productivity, Quaternary temperature and precipitation change) and human impact (human influence index) on bird turnover. ResultsBird taxonomic and trait turnover were highest in the north African deserts and boreal biomes. In the tropics, taxonomic turnover tended to be higher, but trait turnover was lower than in other biomes. Taxonomic and trait turnover exhibited markedly different or even opposing relationships with climatic and topographic gradients, but at their upper quantiles both types of turnover decreased with increasing human influence. Main conclusionsThe influence of regional, environmental and anthropogenic factors differ between bird taxonomic and trait turnover, consistent with an imprint of niche conservatism, environmental filtering and topographic barriers on bird regional assemblages. Human influence on these patterns is pervasive and demonstrates global biotic homogenization at a macroecological scale.  
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  Volume de collection Numéro de collection Edition  
  ISSN 1466-822x ISBN Médium  
  Région Expédition Conférence  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2212  
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