bascule de visibilité Search & Display Options

Tout Sélectionner    Désélectionner
 |   | 
Détails
   print
  Enregistrements Liens (down)
Auteur Loiseau, N.; Gaertner, J.-C.; Kulbicki, M.; Mérigot, B.; Legras, G.; Taquet, M.; Gaertner-Mazouni, N. url  doi
openurl 
  Titre Assessing the multicomponent aspect of coral fish diversity: The impact of sampling unit dimensions Type Article scientifique
  Année 2016 Publication Revue Abrégée Ecological Indicators  
  Volume 60 Numéro Pages 815-823  
  Mots-Clés Evenness; Functional diversity; Index sensitivity; Sampling unit dimensions; species richness; Visual censuses  
  Résumé The influence of variations in sampling unit dimensions on the assessment of fish species structuring has been widely documented. However, this issue has been restricted to a very limited range of community and population indices (mainly species richness and density). Here, we have investigated this issue through the analysis of 13 diversity indices related to 3 diversity components (number of species, evenness and functional diversity). We analyzed a large set of 257 standardized underwater visual census (UVC) transects dealing with 254 coral fish species. The sensitivity of the indices to the variation in sampling unit dimensions was studied by comparing a range of 55 couples of transect length and width representing 34 sampling surfaces. We found that the extent and profile of the sensitivity to changes in transect dimensions strongly varied both from one index to another and from one dimension to another (length and width). The most sensitive indices were more strongly impacted by variation in length than width. We also showed that for a fixed transect surface, the couple of chosen length and width may alter the assessment of indices related to each of the three main diversity components studied. Some widely used diversity indices, such as species richness and Shannon index, appeared to be very sensitive to changes in transect length and width. In contrast, while still very little used in coral fish studies, two functional diversity indices (FDiv, FEve), and to a lesser extent an evenness index (Berger–Parker), remained robust in the face of change in sampling dimensions. By showing that the variation in sampling dimensions (length, width and surface) may impact diversity indices in a contrasting manner, we stress the need to take into account the sensitivity of the indices to this criterion in the process of selection of the indices to be analyzed in diversity studies. Finally, we found that 30 m long*5 m wide transects might be a suitable compromise size for assessing the patterns of each of the three major complementary components of coral fish diversity.  
  Adresse  
  Auteur institutionnel Thèse  
  Editeur Lieu de Publication Éditeur  
  Langue Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 1470-160x ISBN Médium  
  Région Expédition Conférence  
  Notes Approuvé pas de  
  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1320  
Lien permanent pour cet enregistrement
 

 
Auteur Sirot, C.; Villeger, S.; Mouillot, D.; Darnaude, A.M.; Ramos-Miranda, J.; Flores-Hernandez, D.; Panfili, J. url  doi
openurl 
  Titre Combinations of biological attributes predict temporal dynamics of fish species in response to environmental changes Type Article scientifique
  Année 2015 Publication Ecological Indicators Revue Abrégée  
  Volume 48 Numéro Pages 147-156  
  Mots-Clés Ecological and life-history traits; Environmental changes; Estuarine ecosystem; Multivariate index; Species sensitivity; Tropical lagoon  
  Résumé Assessing species vulnerability to environmental changes is a major challenge for conservation. Combinations of biological attributes have already been successfully used for this purpose, allowing large-scale prediction of inter-specific differences in demographic parameters (e.g. abundance) or endangered status. However, studies investigating whether biological attributes could be used to predict the temporal demographic responses of species in a changing environment are still scarce. In this work, we tackled this issue by taking advantage of a multi-decadal survey of concomitant changes in fish communities and environmental conditions within the Terminos lagoon (Mexico). Based on this rare dataset, we first characterized changes in abiotic parameters that occurred in this ecosystem since the 80s. Then, we adapted a multivariate index accounting for changes in both species abundance and occurrence to assess concomitant demographic changes for the 25 dominant fish species in the lagoon, classifying them into five various types of trajectories (“Increasing”, “Decreasing”, “Constant”, “Hump-shape” and “U-shape”). Finally, we assessed the accuracy in prediction of these temporal responses for all possible combinations of 15 biological attributes including taxonomy, ecological and life-history traits. Our results showed that fish specific demographic changes over the last 30 years could be accurately predicted (72% accuracy) using a combination of five biological attributes (spawning season, order, maximum salinity, width of salinity range, oocyte size) among which three could be related to the increase in average salinity occurred in the lagoon over this period. Appropriate sets of complementary biological attributes could similarly allow prediction of inter-specific differences in demographic changes in other areas, thereby offering an additional pragmatic tool for ecosystem managers to identify vulnerable species at the local scale.  
  Adresse  
  Auteur institutionnel Thèse  
  Editeur Lieu de Publication Éditeur  
  Langue Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN ISBN Médium  
  Région Expédition Conférence  
  Notes Approuvé pas de  
  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1112  
Lien permanent pour cet enregistrement
 

 
Auteur Meynard, C.N.; Kaplan, D. url  doi
openurl 
  Titre Using virtual species to study species distributions and model performance Type Article scientifique
  Année 2013 Publication Revue Abrégée Journal of Biogeography  
  Volume 40 Numéro 1 Pages 1-8  
  Mots-Clés Auc; predictive ecology; presence-absence; prevalence; Sensitivity; simulations; specificity; threshold; virtual species  
  Résumé Simulations of virtual species (i.e. species for which the environmentoccupancy relationships are known) are increasingly being used to test the effects of different aspects of modelling and sampling strategy on performance of species distribution models (SDMs). Here we discuss an important step of the simulation process: the translation of simulated probabilities of occurrence into patterns of presence and absence. Often a threshold strategy is used to generate virtual occurrences, where presence always occurs above a specific simulated probability value and never below. This procedure effectively translates any shape of simulated species response into a threshold one and eliminates any stochasticity from the species occupancy pattern. We argue that a probabilistic approach should be preferred instead because the threshold response can be treated as a particular case within this framework. This also allows one to address questions relating to the shape of functional responses and avoids convergence issues with some of the most common SDMs. Furthermore, threshold-based virtual species studies generate over-optimistic performance measures that lack classification error or incorporate error from a mixture of sampling and modelling choices. Incorrect use of a threshold approach can have significant consequences for the practising biogeographer. For example, low model performance may be interpreted as due to sample bias or poor model choice, rather than being related to fundamental biological responses to environmental gradients. We exemplify these shortcomings with a case study where we compare results from threshold and probabilistic simulation approaches.  
  Adresse  
  Auteur institutionnel Thèse  
  Editeur Lieu de Publication Éditeur  
  Langue Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 0305-0270 ISBN Médium  
  Région Expédition Conférence  
  Notes Approuvé pas de  
  Numéro d'Appel LL @ pixluser @ collection 246  
Lien permanent pour cet enregistrement
 

 
Auteur Joo, R.; Bertrand, S.; Chaigneau, A.; Niquen, M. url  doi
openurl 
  Titre Optimization of an artificial neural network for identifying fishing set positions from VMS data : an example from the Peruvian anchovy purse seine fishery Type Article scientifique
  Année 2011 Publication Revue Abrégée Ecological Modelling  
  Volume 222 Numéro Pages 1048-1059  
  Mots-Clés analysis; anchovy; Artificial; fishery; Fishing; locations; Monitoring; networks; neural; purse; seine; Sensitivity; set; System; Vessel  
  Résumé The spatial behavior of numerous fishing fleets is nowadays well documented thanks to satellite Vessel Monitoring Systems (VMS). Vessel positions are recorded on a frequent and regular basis which opens promising perspectives for improving fishing effort estimation and management. However, no specific information is provided on whether the vessel is fishing or not. To answer that question, existing works on VMS data usually apply simple criteria (e.g. threshold on speed). Those simple criteria generally focus in detecting true positives (a true fishing set detected as a fishing set); conversely, estimation errors are given no attention. For our case study, the Peruvian anchovy fishery, those criteria overestimate the total number of fishing sets by 182%. To overcome this problem an artificial neural network (ANN) approach is presented here. In order to set both the optimal parameterization and use “rules” for this ANN, we perform an extensive sensitivity analysis on the optimization of (1) the internal structure and training algorithm of the ANN and (2) the “rules” used for choosing both the relative size and the composition of the databases (DBs) used for training and inferring with the ANN. The “optimized” ANN greatly improves the estimates of the number and location of fishing events. For our case study, ANN reduces the total estimation error on the number of fishing sets to 1% (in average) and obtains 76% of true positives. This spatially explicit information on effort, provided with error estimation, should greatly reduce misleading interpretations of catch per unit effort and thus significantly improve the adaptive management of fisheries. While fitted on Peruvian anchovy fishery data, this type of neural network approach has wider potential and could be implemented in any fishery relying on both VMS and at-sea observer data. In order to increase the accuracy of the ANN results, we also suggest some criteria for improving sampling design by at-sea observers and VMS data.  
  Adresse  
  Auteur institutionnel Thèse  
  Editeur Lieu de Publication Éditeur  
  Langue Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 0304-3800 ISBN Médium  
  Région Expédition Conférence  
  Notes Approuvé pas de  
  Numéro d'Appel LL @ pixluser @ collection 147  
Lien permanent pour cet enregistrement
 

 
Auteur Minguez, L.; Di Poi, C.; Farcy, E.; Ballandonne, C.; Benchouala, A.; Bojic, C.; Cossu-Leguille, C.; Costil, K.; Serpentini, A.; Lebel, J.-M.; Halm-Lemeille, M.-P. url  doi
openurl 
  Titre Comparison of the sensitivity of seven marine and freshwater bioassays as regards antidepressant toxicity assessment Type Article scientifique
  Année 2014 Publication Revue Abrégée Ecotoxicology  
  Volume Numéro Pages 1-11  
  Mots-Clés Antidepressant; Freshwater ecotoxicity; Marine ecotoxicity; Sensitivity comparison; Test battery  
  Résumé  
  Adresse  
  Auteur institutionnel Thèse  
  Editeur Lieu de Publication Éditeur  
  Langue English Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 0963-9292 ISBN Médium  
  Région Expédition Conférence  
  Notes Approuvé pas de  
  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 491  
Lien permanent pour cet enregistrement
Tout Sélectionner    Désélectionner
 |   | 
Détails
   print

Save Citations:
Export Records: