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Auteur McLean, M.; Mouillot, D.; Lindegren, M.; Villeger, S.; Engelhard, G.; Murgier, J.; Auber, A.
Titre Fish communities diverge in species but converge in traits over three decades of warming Type Article scientifique
Année 2019 Publication Revue Abrégée Glob. Change Biol.
Volume 25 Numéro 11 Pages 3972-3984
Mots-Clés biodiversity; biotic homogenization; climate change; climate-change; community ecology; consequences; ecological traits; ecology; ecosystem functioning; fisheries; functional diversity; north-sea; patterns; plant traits; regime shift; shelf seas; spatio-temporal dynamics
Résumé Describing the spatial and temporal dynamics of communities is essential for understanding the impacts of global environmental change on biodiversity and ecosystem functioning. Trait-based approaches can provide better insight than species-based (i.e. taxonomic) approaches into community assembly and ecosystem functioning, but comparing species and trait dynamics may reveal important patterns for understanding community responses to environmental change. Here, we used a 33-year database of fish monitoring to compare the spatio-temporal dynamics of taxonomic and trait structure in North Sea fish communities. We found that the majority of variation in both taxonomic and trait structure was explained by a pronounced spatial gradient, with distinct communities in the southern and northern North Sea related to depth, sea surface temperature, salinity and bed shear stress. Both taxonomic and trait structure changed significantly over time; however taxonomically, communities in the south and north diverged towards different species, becoming more dissimilar over time, yet they converged towards the same traits regardless of species differences. In particular, communities shifted towards smaller, faster growing species with higher thermal preferences and pelagic water column position. Although taxonomic structure changed over time, its spatial distribution remained relatively stable, whereas in trait structure, the southern zone of the North Sea shifted northward and expanded, leading to homogenization. Our findings suggest that global environmental change, notably climate warming, will lead to convergence towards traits more adapted for novel environments regardless of species composition.
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Volume de collection Numéro de collection Edition
ISSN 1354-1013 ISBN Médium
Région Expédition Conférence
Notes WOS:000482780600001 Approuvé pas de
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Auteur Letessier, T.B.; Mouillot, D.; Bouchet, P.J.; Vigliola, L.; Fernandes, M.C.; Thompson, C.; Boussarie, G.; Turner, J.; Juhel, J.-B.; Maire, E.; Caley, M.J.; Koldewey, H.J.; Friedlander, A.; Sala, E.; Meeuwig, J.J.
Titre Remote reefs and seamounts are the last refuges for marine predators across the Indo-Pacific Type Article scientifique
Année 2019 Publication Revue Abrégée PLoS. Biol.
Volume 17 Numéro 8 Pages e3000366
Mots-Clés biodiversity; coastal; consequences; hotspots; mortality; ocean; patterns; protected areas; shark sanctuary; tracking
Résumé Since the 1950s, industrial fisheries have expanded globally, as fishing vessels are required to travel further afield for fishing opportunities. Technological advancements and fishery subsidies have granted ever-increasing access to populations of sharks, tunas, billfishes, and other predators. Wilderness refuges, defined here as areas beyond the detectable range of human influence, are therefore increasingly rare. In order to achieve marine resources sustainability, large no-take marine protected areas (MPAs) with pelagic components are being implemented. However, such conservation efforts require knowledge of the critical habitats for predators, both across shallow reefs and the deeper ocean. Here, we fill this gap in knowledge across the Indo-Pacific by using 1,041 midwater baited videos to survey sharks and other pelagic predators such as rainbow runner (Elagatis bipinnulata), mahimahi (Coryphaena hippurus), and black marlin (Istiompax indica). We modeled three key predator community attributes: vertebrate species richness, mean maximum body size, and shark abundance as a function of geomorphology, environmental conditions, and human pressures. All attributes were primarily driven by geomorphology (35%-62% variance explained) and environmental conditions (14%-49%). While human pressures had no influence on species richness, both body size and shark abundance responded strongly to distance to human markets (12%-20%). Refuges were identified at more than 1,250 km from human markets for body size and for shark abundance. These refuges were identified as remote and shallow seabed features, such as seamounts, submerged banks, and reefs. Worryingly, hotpots of large individuals and of shark abundance are presently under-represented within no-take MPAs that aim to effectively protect marine predators, such as the British Indian Ocean Territory. Population recovery of predators is unlikely to occur without strategic placement and effective enforcement of large no-take MPAs in both coastal and remote locations.
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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 1544-9173 ISBN Médium
Région Expédition Conférence
Notes WOS:000483408500011 Approuvé pas de
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Auteur Leroy, B.; Dias, M.S.; Giraud, E.; Hugueny, B.; Jezequel, C.; Leprieur, F.; Oberdorff, T.; Tedesco, P.A.
Titre Global biogeographical regions of freshwater fish species Type Article scientifique
Année 2019 Publication Revue Abrégée J. Biogeogr.
Volume Numéro Pages
Mots-Clés actinopterygians; biogeographical regions; biogeography; bioregionalization; bioregions; connectivity; dispersal; diversity; evolution; freshwater fish; history; homogenization; network; patterns; richness; transition zones; vicariance; world; zoogeographical regions
Résumé Aim To define the major biogeographical regions and transition zones for freshwater fish species. Taxon Strictly freshwater species of actinopterygian fish (i.e. excluding marine and amphidromous fish families). Methods We based our bioregionalization on a global database of freshwater fish species occurrences in drainage basins, which, after filtering, includes 11,295 species in 2,581 basins. On the basis of this dataset, we generated a bipartite (basin-species) network upon which we applied a hierarchical clustering algorithm (the Map Equation) to detect regions. We tested the robustness of regions with a sensitivity analysis. We identified transition zones between major regions with the participation coefficient, indicating the degree to which a basin has species from multiple regions. Results Our bioregionalization scheme showed two major supercontinental regions (Old World and New World, 50% species of the world and 99.96% endemics each). Nested within these two supercontinental regions lie six major regions (Nearctic, Neotropical, Palearctic, Ethiopian, Sino-Oriental and Australian) with extremely high degrees of endemism (above 96% except for the Palearctic). Transition zones between regions were of limited extent compared to other groups of organisms. We identified numerous subregions with high diversity and endemism in tropical areas (e.g. Neotropical), and a few large subregions with low diversity and endemism at high latitudes (e.g. Palearctic). Main conclusions Our results suggest that regions of freshwater fish species were shaped by events of vicariance and geodispersal which were similar to other groups, but with freshwater-specific processes of isolation that led to extremely high degrees of endemism (far exceeding endemism rates of other continental vertebrates), specific boundary locations and limited extents of transition zones. The identified bioregions and transition zones of freshwater fish species reflect the strong isolation of freshwater fish faunas for the past 10-20 million years. The extremely high endemism and diversity of freshwater fish fauna raises many questions about the biogeographical consequences of current introductions and extinctions.
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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 0305-0270 ISBN Médium
Région Expédition Conférence
Notes WOS:000484392300001 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection (down) 2637
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Auteur Escalas, A.; Catherine, A.; Maloufi, S.; Cellamare, M.; Hamlaoui, S.; Yepremian, C.; Louvard, C.; Troussellier, M.; Bernard, C.
Titre Drivers and ecological consequences of dominance in periurban phytoplankton communities using networks approaches Type Article scientifique
Année 2019 Publication Revue Abrégée Water Res.
Volume 163 Numéro Pages Unsp-114893
Mots-Clés blooms; climate-change; Co-occurrence network; Community cohesion; Community functioning; cooccurrence patterns; cyanobacteria dominance; diversity; Dominance; fresh-waters; lakes; light; Periurban waterbodies; Phytoplankton; resource use efficiency; species richness
Résumé Evaluating the causes and consequences of dominance by a limited number of taxa in phytoplankton communities is of huge importance in the current context of increasing anthropogenic pressures on natural ecosystems. This is of particular concern in densely populated urban areas where usages and impacts of human populations on water ecosystems are strongly interconnected. Microbial biodiversity is commonly used as a bioindicator of environmental quality and ecosystem functioning, but there are few studies at the regional scale that integrate the drivers of dominance in phytoplankton communities and their consequences on the structure and functioning of these communities. Here, we studied the causes and consequences of phytoplankton dominance in 50 environmentally contrasted waterbodies, sampled over four summer campaigns in the highly-populated Ile-de-France region (IDF). Phytoplankton dominance was observed in 32-52% of the communities and most cases were attributed to Chlorophyta (35.5-40.6% of cases) and Cyanobacteria (30.3-36.5%). The best predictors of dominance were identified using multinomial logistic regression and included waterbody features (surface, depth and connection to the hydrological network) and water column characteristics (total N, TN:TP ratio, water temperature and stratification). The consequences of dominance were dependent on the identity of the dominant organisms and included modifications of biological attributes (richness, cohesion) and functioning (biomass, RUE) of phytoplankton communities. We constructed co-occurrence networks using high resolution phytoplankton biomass and demonstrated that networks under dominance by Chlorophyta and Cyanobacteria exhibited significantly different structure compared with networks without dominance. Furthermore, dominance by Cyanobacteria was associated with more profound network modifications (e.g. cohesion, size, density, efficiency and proportion of negative links), suggesting a stronger disruption of the structure and functioning of phytoplankton communities in the conditions in which this group dominates. Finally, we provide a synthesis on the relationships between environmental drivers, dominance status, community attributes and network structure. (C) 2019 Elsevier Ltd. All rights reserved.
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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 0043-1354 ISBN Médium
Région Expédition Conférence
Notes WOS:000483006400038 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection (down) 2636
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Auteur Draredja, M.A.; Frihi, H.; Boualleg, C.; Gofart, A.; Abadie, E.; Laabir, M.
Titre Seasonal variations of phytoplankton community in relation to environmental factors in a protected meso-oligotrophic southern Mediterranean marine ecosystem (Mellah lagoon, Algeria) with an emphasis of HAB species Type Article scientifique
Année 2019 Publication Revue Abrégée Environ. Monit. Assess.
Volume 191 Numéro 10 Pages 603
Mots-Clés coastal lagoons; Diversity; dynamics; Environmental conditions; HAB species; Mediterranean lagoon; nutrients; particulate matter; patterns; Phytoplankton monitoring; sea; temporal variations; thau lagoon; venice lagoon; water-quality
Résumé The spatial and temporal variation of phytoplankton communities including HAB species in relation to the environmental characteristics was investigated in the protected meso-oligotrophic Mellah lagoon located in the South Western Mediterranean. During 2016, a biweekly monitoring of phytoplankton assemblages and the main abiotic factors were realized at three representative stations. Taxonomic composition, abundance, and diversity index were determined. In total, 227 phytoplankton species (160 diatoms and 53 dinoflagellates) were inventoried. There was a clear dominance of diatoms (62.9%) compared with dinoflagellates (36.8%). Diatoms dominated in spring and dinoflagellates developed in summer and early autumn in Mellah showing a marked seasonal trend. Data showed that the dynamic of the phytoplankton taxa evolving in the lagoon was mainly driven by temperature and salinity. For the first time, a number of potentially toxic species have been identified, including 2 diatoms (Pseudo-nitzschia group delicatissima, Pseudo-nitzschia group seriata) and 5 dinoflagellates (Alexandrium minutum, Alexandrium tamarense/catenella, Dinophysis acuminata, Dinophysis sacculus, Prorocentrum lima). These harmful species could threat the functioning of the Mellah lagoon and human health and require the establishment of a monitoring network. Finally, our study suggests that the observed decrease of the phytoplankton diversity between 2001 and 2016 could result from the reduction in water exchanges between the lagoon and the adjacent coast following the gradual clogging of the channel.
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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 0167-6369 ISBN Médium
Région Expédition Conférence
Notes WOS:000484493700001 Approuvé pas de
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