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Auteur Benedetti, F.; Vogt, M.; Righetti, D.; Guilhaumon, F.; Ayata, S.-D.
Titre Do functional groups of planktonic copepods differ in their ecological niches? Type (up) Article scientifique
Année 2018 Publication Revue Abrégée J. Biogeogr.
Volume 45 Numéro 3 Pages 604-616
Mots-Clés climate-change; copepods; species distribution models; north-atlantic; calanus-finmarchicus; mediterranean sea; environmental niche; functional groups; lipid pump; marine ecosystem; oithona-similis; pseudo-absences; trait biogeography; zooplankton; zooplankton fecal pellets
Résumé Aim: To assess the degree of overlap between the environmental niches of marine planktonic copepods and test if the distribution of copepod functional groups differs across environmental gradients. Location: The Mediterranean Sea. Methods: Functional groups were defined based on clustering of functional traits in 106 marine copepod species using a multivariate ordination analysis. Functional traits included maximum body length, feeding mode, spawning strategy and trophic group. Simultaneously, the global distribution of the species was used to model their environmental niches with six environmental variables. For each of these predictors, four niche parameters were derived from the univariate response curve of each species to summarise their environmental preferences and ordinate the species in niche space through a PCA. Finally, the differences in the position in niche space of functional groups were tested with variance analysis. Results: We identified seven copepod functional groups with different distributions along the environmental gradients covered by our study. While carnivorous functional groups were affiliated with oligotrophic and tropical conditions, large and small current-feeding herbivores are associated with colder, more seasonally varying and productive conditions. Small cruising detritivores and other small current-feeding herbivores were not affiliated with specific conditions as their constituting species were scattered in niche space. Main conclusions: Since copepod functional groups occupy distinct ecological niches, ecosystem processes related to these groups are expected to vary across environmental gradients. Conditions favouring large current-feeding herbivores should allow for enhanced fluxes of energy and nutrients through Mediterranean Sea ecosystems, while such fluxes should be weakened where large carnivores and small passive ambush-feeding copepods dominate. Our study supports the development of trait-based zooplankton functional groups in marine ecosystem models.
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ISSN 0305-0270 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2311
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Auteur Mannocci, L.; Roberts, J.J.; Halpin, P.N.; Authier, M.; Boisseau, O.; Bradai, M.N.; Canadas, A.; Chicote, C.; David, L.; Di-Meglio, N.; Fortuna, C.M.; Frantzis, A.; Gazo, M.; Genov, T.; Hammond, P.S.; Holcer, D.; Kaschner, K.; Kerem, D.; Lauriano, G.; Lewis, T.; di Sciara, G.N.; Panigada, S.; Antonio Raga, J.; Scheinin, A.; Ridoux, V.; Vella, A.; Vella, J.
Titre Assessing cetacean surveys throughout the Mediterranean Sea: a gap analysis in environmental space Type (up) Article scientifique
Année 2018 Publication Revue Abrégée Sci Rep
Volume 8 Numéro Pages 3126
Mots-Clés species distribution models; tursiops-truncatus; population-structure; sperm-whales; bottle-nosed dolphins; fin whales; habitat preference; pelagos sanctuary; seasonal distribution; whales balaenoptera-physalus
Résumé Heterogeneous data collection in the marine environment has led to large gaps in our knowledge of marine species distributions. To fill these gaps, models calibrated on existing data may be used to predict species distributions in unsampled areas, given that available data are sufficiently representative. Our objective was to evaluate the feasibility of mapping cetacean densities across the entire Mediterranean Sea using models calibrated on available survey data and various environmental covariates. We aggregated 302,481 km of line transect survey effort conducted in the Mediterranean Sea within the past 20 years by many organisations. Survey coverage was highly heterogeneous geographically and seasonally: large data gaps were present in the eastern and southern Mediterranean and in non-summer months. We mapped the extent of interpolation versus extrapolation and the proportion of data nearby in environmental space when models calibrated on existing survey data were used for prediction across the entire Mediterranean Sea. Using model predictions to map cetacean densities in the eastern and southern Mediterranean, characterised by warmer, less productive waters, and more intense eddy activity, would lead to potentially unreliable extrapolations. We stress the need for systematic surveys of cetaceans in these environmentally unique Mediterranean waters, particularly in non-summer months.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 2045-2322 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2312
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Auteur Ottimofiore, E.; Albouy, C.; Leprieur, F.; Descombes, P.; Kulbicki, M.; Mouillot, D.; Parravicini, V.; Pellissier, L.
Titre Responses of coral reef fishes to past climate changes are related to life-history traits Type (up) Article scientifique
Année 2017 Publication Revue Abrégée Ecol. Evol.
Volume 7 Numéro 6 Pages 1996-2005
Mots-Clés climate change; dispersal; diversity; environmental-change; future; global patterns; Indo-Pacific Ocean; range shifts; refugia; richness; sea-level; species distribution; species distribution models; temperature
Résumé Coral reefs and their associated fauna are largely impacted by ongoing climate change. Unravelling species responses to past climatic variations might provide clues on the consequence of ongoing changes. Here, we tested the relationship between changes in sea surface temperature and sea levels during the Quaternary and present-day distributions of coral reef fish species. We investigated whether species-specific responses are associated with life-history traits. We collected a database of coral reef fish distribution together with life-history traits for the Indo-Pacific Ocean. We ran species distribution models (SDMs) on 3,725 tropical reef fish species using contemporary environmental factors together with a variable describing isolation from stable coral reef areas during the Quaternary. We quantified the variance explained independently by isolation from stable areas in the SDMs and related it to a set of species traits including body size and mobility. The variance purely explained by isolation from stable coral reef areas on the distribution of extant coral reef fish species largely varied across species. We observed a triangular relationship between the contribution of isolation from stable areas in the SDMs and body size. Species, whose distribution is more associated with historical changes, occurred predominantly in the Indo-Australian archipelago, where the mean size of fish assemblages is the lowest. Our results suggest that the legacy of habitat changes of the Quaternary is still detectable in the extant distribution of many fish species, especially those with small body size and the most sedentary. Because they were the least able to colonize distant habitats in the past, fish species with smaller body size might have the most pronounced lags in tracking ongoing climate change.
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ISSN 2045-7758 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2108
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Auteur Meynard, C.N.; Kaplan, D.M.; Leroy, B.
Titre Detecting outliers in species distribution data: Some caveats and clarifications on a virtual species study Type (up) Article scientifique
Année 2019 Publication Revue Abrégée J. Biogeogr.
Volume 46 Numéro 9 Pages 2141-2144
Mots-Clés enm; observation errors; outliers; prevalence; probabilistic approach; sample bias; simulations; species distribution models; thresholds; virtual ecology; virtual species
Résumé Liu et al. (2018) used a virtual species approach to test the effects of outliers on species distribution models. In their simulations, they applied a threshold value over the simulated suitabilities to generate the species distributions, suggesting that using a probabilistic simulation approach would have been more complex and yield the same results. Here, we argue that using a probabilistic approach is not necessarily more complex and may significantly change results. Although the threshold approach may be justified under limited circumstances, the probabilistic approach has multiple advantages. First, it is in line with ecological theory, which largely assumes non-threshold responses. Second, it is more general, as it includes the threshold as a limiting case. Third, it allows a better separation of the relevant intervening factors that influence model performance. Therefore, we argue that the probabilistic simulation approach should be used as a general standard in virtual species studies.
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ISSN 0305-0270 ISBN Médium
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Notes WOS:000483602900019 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2640
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Auteur Authier, M.; Saraux, C.; Péron, C.
Titre Variable selection and accurate predictions in habitat modelling: a shrinkage approach Type (up) 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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ISSN 0906-7590 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2130
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