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| Registros recuperados: 14 | |
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| Legras, Gaëlle; Loiseau, Nicolas; Gaertner, Jean-claude; Poggiale, J-c.; Gaertner-mazouni, N.. |
| The impact of the variation of the number of functional traits on functional diversity assessment is still poorly known. Although the covariation between these two parameters may be desirable in some situations (e.g. if adding functional traits provides relevant new functional information), it may also result from mathematical artefacts and lead to misinterpretation of the results obtained. Here, we have tested the behaviour of a set of nine indices widely used for assessing the three main components of functional diversity (i.e. functional richness, evenness and divergence), according to the variation in the number of functional traits. We found that the number of functional traits may strongly impact the values of most of the indices considered, whatever... |
| Tipo: Text |
Palavras-chave: Functional traits; Dissimilarity metric; Functional diversity; Index sensitivity; Trend analysis. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00503/61438/65561.pdf |
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| Legras, Gaëlle; Loiseau, Nicolas; Gaertner, Jean-claude; Poggiale, Jean-christophe; Lenco, Dino; Mazouni, Nabila; Mérigot, Bastien. |
| Describing how communities change over space and time is crucial to better understand and predict the functioning of ecosystems. We propose a new methodological framework, based on network theory and modularity concept, to determine which type of mechanisms (i.e. deterministic versus stochastic processes) has the strongest influence on structuring communities. This framework is based on the computation and comparison of two networks: the co-occurrence (based on species abundances) and the functional networks (based on the species traits values). In this way we can assess whether the species belonging to a given functional group also belong to the same co-occurrence group. We adapted the Dg index of Gauzens et al. (2015) to analyze congruence between both... |
| Tipo: Text |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00599/71142/69458.pdf |
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| Taquet, Marc; Blanc, Michel; Dagorn, Laurent; Filmalter, John David; Fonteneau, Alain; Forget, Fabien; Gaertner, Jean-claude; Galzin, René; Gervain, Paul; Goujon, Michel; Guillotreau, Patrice; Guyader, Olivier; Hall, Martin; Holland, Kim; Itano, David; Monteagudo, Jean-pierre; Morales-nin, Beatriz; Reynal, Lionel; Sharp, Michael; Sokimi, Williams; Tanetoa, Mainui; Yen Kai Sun, Stephen. |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00115/22657/20383.pdf |
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| Poisson, Francois; Gaertner, Jean-claude; Taquet, Marc; Durbec, Jean-pierre; Bigelow, Keith. |
| Commercial longline fishing data were analyzed and experiments were conducted with gear equipped with hook timers and time-depth recorders in the Reunion Island fishery (21 degrees 5'S lat., 53 degrees 28'E long.) to elucidate direct and indirect effects of the lunar cycle and other operational factors that affect catch rates, catch composition, fish behavior, capture time, and fish survival. Logbook data from 1998 through 2000, comprising 2009 sets, indicated that swordfish (Xiphias gladius) catch-per unit of effort (CPUE) increased during the first and last quarter of the lunar phase, whereas albacore (Thunnus alalunga) CPUE was highest during the full moon. Swordfish were caught rapidly after the longline was set and, like bigeye tuna (Thunnus obesus),... |
| Tipo: Text |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00011/12237/9019.pdf |
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| Legras, G.; Loiseau, Nicolas; Gaertner, Jean-claude. |
| Functional richness, currently defined as the amount of niche space occupied by the species within a community, is one of the three major components of functional diversity. Different indices have been developed in order to quantify this component. However, the range of indices available for assessing functional richness, often mathematically complex and based on different rationales, can cause confusion for field ecologists and lead to misinterpretation of the results obtained. In this context, we have provided the first study exclusively focused on the comparison of the definitions, advantages and drawbacks of a large set of functional richness indices. The first part of this work is focused on four indices (FDP&G, FRic, TOP and N-hypervolumes... |
| Tipo: Text |
Palavras-chave: Functional richness indices; Index properties; Limitations; Guidelines. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00435/54666/59606.pdf |
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| Loiseau, Nicolas; Gaertner, Jean-claude. |
| We present the first representative and quantified overview of the indices used worldwide for assessing the biodiversity of coral reef fishes. On this basis, we discuss the suitability and drawbacks of the indices most widely used in the assessment of coral fish biodiversity. An extensive and systematic survey of the literature focused on coral reef fish biodiversity was conducted from 1990 up to the present. We found that the multicomponent aspect of biodiversity, which is considered as a key feature of biodiversity for numerous terrestrial and marine ecosystems, has been poorly taken into account in coral reef fish studies. Species richness is still strongly dominant while other diversity components, such as functional diversity, are underestimated even... |
| Tipo: Text |
Palavras-chave: Coral reef fishes; Diversity indices; Monitoring; Multicomponent; Review. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00286/39686/80168.pdf |
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| Gaertner, Jean-claude; Maiorano, Porza; Merigot, Bastien; Colloca, Francesco; Politou, Chrissi-yianna; Gil De Sola, Luis; Bertrand, Jacques; Murenu, Matteo; Durbec, Jean-pierre; Kallianiotis, Argyris; Mannini, Alessandro. |
| Large-scale studies focused on the diversity of continental slope ecosystems are still rare, usually restricted to a limited number of diversity indices and mainly based on the empirical comparison of heterogeneous local data sets. In contrast, we investigate large-scale fish diversity on the basis of multiple diversity indices and using 1454 standardized trawl hauls collected throughout the upper and middle slope of the whole northern Mediterranean Sea (36 degrees 3' - 45 degrees 7' N; 5 degrees 3'W - 28 degrees E). We have analyzed (1) the empirical relationships between a set of 11 diversity indices in order to assess their degree of complementarity/redundancy and (2) the consistency of spatial patterns exhibited by each of the complementary groups of... |
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| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00152/26299/24392.pdf |
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| Granger, Victoria; Fromentin, Jean-marc; Bez, Nicolas; Relini, Giulio; Meynard, Christine N.; Gaertner, Jean-claude; Maiorano, Porzia; Garcia Ruiz, Cristina; Follesa, Cristina; Gristina, Michele; Peristeraki, Panagiota; Brind'Amour, Anik; Carbonara, Pierluigi; Charilaou, Charis; Esteban, Antonio; Jadaud, Angelique; Joksimovic, Aleksandar; Kallianiotis, Argyris; Kolitari, Jerina; Manfredi, Chiara; Massuti, Enric; Mifsud, Roberta; Quetglas, Antoni; Refes, Wahid; Sbrana, Mario; Vrgoc, Nedo; Spedicato, Maria Teresa; Merigot, Bastien. |
| Increasing human pressures and global environmental change may severely affect the diversity of species assemblages and associated ecosystem services. Despite the recent interest in phylogenetic and functional diversity, our knowledge on large spatio-temporal patterns of demersal fish diversity sampled by trawling remains still incomplete, notably in the Mediterranean Sea, one of the most threatened marine regions of the world. We investigated large spatio-temporal diversity patterns by analysing a dataset of 19,886 hauls from 10 to 800 m depth performed annually during the last two decades by standardized scientific bottom trawl field surveys across the Mediterranean Sea, within the MEDITS program. A multi-component (eight diversity indices) and... |
| Tipo: Text |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00216/32743/31322.pdf |
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| Gaertner, Jean-claude; Merigot, Bastien; Relini, Giulio; Bertrand, Jacques; Mazouni, Nabila; Politou, Chrissi-yianna; Gil De Sola, Luis; Kallianiotis, Argyris; Carpentieri, Paolo; Murenu, Matteo; Durbec, Jean-pierre; Vrgoc, Nedo; Ungaro, Nicola. |
| Recent theoretical and field studies conducted in both terrestrial and marine ecosystems have suggested that diversity could be a more complex and multi-component concept than previously thought. However, it is still poorly understood to what extent the information provided by the various indices is complementary with regard to diversity, and to what extent this complementarity is reproducible in different situations or at different scales of observation. In the present work, we have analysed the reproducibility of the empirical relationships between 11 diversity indices related to four major aspects (components) of species diversity (species richness, rarity, evenness and species taxonomy) in order to determine whether there is a general pattern of... |
| Tipo: Text |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00029/14064/11382.pdf |
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| Mérigot, Bastien; Gaertner, Jean-claude; Brind’amour, Anik; Carbonara, Pierluigi; Esteban, Antonio; Garcia-ruiz, Cristina; Gristina, Michele; Imzilen, Taha; Jadaud, Angelique; Joksimovic, Aleksandar; Kavadas, Stefanos; Kolitari, Jerina; Maina, Irida; Maiorano, Porzia; Manfredi, Chiara; Micallef, Reno; Peristeraki, Panagiota; Relini, Giulio; Sbrana, Mario; Spedicato, Maria Teresa; Thasitis, Ioannis; Vittori, Stefania; Vrgoc, Nedo. |
| Trawling pressure and environmental changes may affect the composition of fish assemblages. Our knowledge on large spatio-temporal patterns of demersal fish composition remains incomplete for the Mediterranean Sea. We investigated (1) the spatio-temporal stability of demersal assemblages, (2) the relationships between these assemblages and potential structuring factors (trawling pressure and environmental conditions) in order to assess the dynamic of the assemblage structure at the scale of the northern Mediterranean Sea. We analysed a dataset of 18062 hauls from 10 to 800 m depth performed annually during the last two decades across 17 Geographical Sub-Areas (GSAs) (MEDITS program). A multi-table analysis (STATICO-CoA) evidenced a strong inter-GSAs... |
| Tipo: Text |
Palavras-chave: Species composition; Stability; Demersal assemblages; Environment; Fishing pressure; Large scale; Co-inertia analysis; STATICO-CoA. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00584/69629/67485.pdf |
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| Taquet, Marc; Gaertner, Jean-claude; Bertrand, Jacques. |
| This work aims to define a typology of trawler f1eet in Sète, the main fishing harbour along the French Mediterranean coast, using several multivariate analysis methods. The fishing ships taken to account are represented by annual profiles of landing specific compositions. Five fishing strategies have been identified. A segmentation method using symbolic objects allows a formaI characterisation of the different strategies. These strategies are studied according to several general characteristics usually used for management rules elaboration (power, length, ship age). The typological analysis allows to characterise two main exploitation ways, one directed to the catch of a few species (Engraulis encrasicolus, Sardina pilchardus), the other characterised by... |
| Tipo: Text |
Palavras-chave: Flotille; Stratégie; Chalutage; Analyse multivariée; Méditerranée; Fleet; Strategy; Fish trawling; Multivariate analysis; Mediterranean sea. |
| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00113/22404/20101.pdf |
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| Registros recuperados: 14 | |
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