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Auteur Kopf, R.K.; Yen, J.D.L.; Nimmo, D.G.; Brosse, S.; Villeger, S.
Titre Global patterns and predictors of trophic position, body size and jaw size in fishes Type Article scientifique
Année (down) 2021 Publication Revue Abrégée Glob. Ecol. Biogeogr.
Volume 30 Numéro 2 Pages 414-428
Mots-Clés allometric trophic network models; allometry; body mass; cross-validation; evolution; food-web; gape limitation; machine learning; mass; model; morphology; predator– prey; random forest; stability; trophic network theory
Résumé Aim The aim of this study was test whether maximum body mass and jaw length are reliable predictors of trophic position (TP) in fishes, and to compare linear and nonlinear machine-learning (ML) models incorporating biogeography, habitat and other morphological traits. Location Global. Time period Modern. Major taxa studied Fishes. Methods We compiled a global database of TP (2.0-4.5), maximum body mass, jaw length, order, ecoregion, habitat and other morphological traits of freshwater, estuarine and diadromous fishes (n = 1,991). We used Bayesian linear mixed effects and ML, with r(2) analogues and 10-fold cross-validation, to explain and predict TP. Results Random forest models outperformed Bayesian models in all comparisons. Jaw length was the most influential predictor of TP, but was weakly associated with body mass except in five orders of largely piscivorous fishes. Trophic position did not scale positively with body mass in global ecoregions, riverine fishes, or in 29/30 orders, but scaled positively in lacustrine fishes and Perciformes. Significant negative TP-body mass scaling was observed in Characiformes. Best models explained 55% of the global variation in TP, but over-estimated the position of herbivores-detritivores, and under-estimated the position of top predators. Main conclusions Our study provides support for jaw length as an important mechanism constraining TP in one of the world's largest groups of vertebrates. Jaw length and body mass were weakly correlated, and therefore body size was not a strong predictor of TP. The diversification of large-bodied herbivores-detritivores and omnivores in freshwater ecosystems, coupled with small predators in species-rich orders (e.g., Cypriniformes, Characiformes) in temperate and tropical rivers explains why TP globally shows a weak relationship with body size. Our model validation results underscore the importance of not assuming that explanatory power extends to predictive capacity in macroecology and machine-learning models.
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ISSN 1466-822x ISBN Médium
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Notes WOS:000591648500001 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2947
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Auteur Bourdaud, P.; Ben Rais Lasram, F.; Araignous, E.; Champagnat, J.; Grusd, S.; Halouani, G.; Hattab, T.; Leroy, B.; Nogues, Q.; Raoux, A.; Safi, G.; Niquil, N.
Titre Impacts of climate change on the Bay of Seine ecosystem: Forcing a spatio-temporal trophic model with predictions from an ecological niche model Type Article scientifique
Année (down) 2021 Publication Revue Abrégée Fish Oceanogr.
Volume Numéro Pages
Mots-Clés climate change; ecological niche modelling; Ecospace; fisheries; trophic interactions
Résumé Climate change is already known to cause irreversible impacts on ecosystems that are difficult to accurately predict due to the multiple scales at which it will interact. Predictions at the community level are mainly focused on the future distribution of marine species biomass using ecological niche modelling, which requires extensive efforts concerning the effects that trophic interactions could have on the realized species dynamics. In this study, a set of species distribution models predictions were used to force the spatially-explicit trophic model Ecospace in order to evaluate the potentials impacts that two 2,100 climate scenarios, RCP2.6 and RCP8.5, could have on a highly exploited ecosystem, the Bay of Seine (France). Simulations demonstrated that both scenarios would influence the community of the Bay of Seine ecosystem: as expected, more intense changes were predicted with the extreme scenario RCP8.5 than with the RCP2.6 scenario. Under both scenarios, a majority of species underwent a decrease of biomass, although some increased. However, in both cases the stability of the majority of species dynamics was lowered, the sustainability of the fishery. Differences between niche modelling predictions and those obtained through the forcing in Ecospace highlighted the paramount importance of considering trophic interactions in climate change simulations. These results illustrate the requirement of multiplying novel approaches for efficiently forecasting potential impacts of climate change.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 1054-6006 ISBN Médium
Région Expédition Conférence
Notes WOS:000623888200001 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2992
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Auteur Jones, A.G.; Dubois, S.F.; Desroy, N.; Fournier, J.
Titre Intertidal ecosystem engineer species promote benthic-pelagic coupling and diversify trophic pathways Type Article scientifique
Année (down) 2021 Publication Revue Abrégée Mar. Ecol.-Prog. Ser.
Volume 660 Numéro Pages 119-139
Mots-Clés cultivated oysters; delta-c-13; delta-n-15; food; Food web; Gardening hypothesis; Habitat modifier; landscape; microphytobenthos; Microphytobenthos; mytilus-edulis; Non-trophic interactions; reefs; sabellaria-alveolata polychaeta; Stable isotopes; stable-isotope ratios; Suspension-feeding
Résumé Ecosystem engineering is a ubiquitous process by which the biological activity of a species shapes habitat diversity and often creates local biodiversity hotspots. The honeycomb-worm Sabellaria alveolata, an intertidal ecosystem engineer, actively builds reefs across Europe by aggregating sand. Here, we used carbon and nitrogen isotopic compositions measured on basal resources and bentho-demersal consumers (fish, mega- and macroinvertebrates) to empirically investigate how non-trophic interactions (ecosystem engineering) modify food web structure and functioning. Three sediment types corresponding to different substrata and species assemblages were sampled: a control soft sediment (medium to muddy sand, before the establishment of S. alveolata), the sediment engineered by S. alveolata (hardened 3D structures), and the soft sediment under the influence of S. alveolata (associated sediment). Using consumer community isotopic biplots (biomass-weighted), niche metrics (standard ellipse area), and mixing models, we found that S. alveolata, through the physical structure it creates, the stimulation of basal resources (microphytobenthos and Ulva), and the diversification of suspension-feeding species, promotes benthic-pelagic coupling and a habitat-wide form of 'gardening,' which further leads to trophic pathway diversification and limits trophic competition between the engineer species and associated suspension-feeders. Furthermore, our results help to refine the definition of S. alveolata reefs as the sum of the engineered and associated sediments since they are part of a single reef food web coupled by the stimulated basal resources and consumers. Finally, the non-trophic and trophic interactions mediated by S. alveolata and the associated macrofauna seem to promote the establishment of a temporally stable and probably highly resilient reef habitat.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 0171-8630 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2998
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Auteur Olokotum, M.; Mitroi, V.; Troussellier, M.; Semyalo, R.; Bernard, C.; Montuelle, B.; Okello, W.; Quiblier, C.; Humbert, J.-F.
Titre A review of the socioecological causes and consequences of cyanobacterial blooms in Lake Victoria Type Article scientifique
Année (down) 2020 Publication Revue Abrégée Harmful Algae
Volume 96 Numéro Pages 101829
Mots-Clés climate-change; Consequences of cyanobacterial blooms; Cyanobacteria; East Africa; Eutrophication; harmful algal blooms; introduced nile perch; Lake Victoria; land-use; lates-niloticus; microcystin concentrations; murchison bay; nutrient concentrations; nyanza gulf; oreochromis-niloticus; Potential toxicity; Socioecological analysis
Résumé Africa is experiencing high annual population growth in its major river basins. This growth has resulted in significant land use change and pollution pressures on the freshwater ecosystems. Among them, the Lake Victoria basin, with more than 42 million people, is a unique and vital resource that provides food and drinking water in East Africa. However, Lake Victoria (LV) has experienced a progressive eutrophication and substantial changes in the fish community leading to recurrent proliferation of water hyacinth and cyanobacteria. Based on an extensive literature review, we show that cyanobacterial biomasses and microcystin concentrations are higher in the bays and gulfs (B&Gs) than in the open lake (OL), with Microcystis and Dolichospermum as the dominant genera. These differences between the B&Gs and the OL are due to differences in their hydrological conditions and in the origins, type and quantities of nutrients. Using data from the literature, we describe the multiple ways in which the human population growth in the LV watershed is connected to the increasing occurrence of cyanobacterial blooms in the OL and B&Gs. We also described the consequences of cyanobacterial blooms on food resources and fishing and on direct water use and water supply of local populations, with their potential consequences on the human health. Finally, we discuss the actions that have been taken for the protection of LV. Although many projects have been implemented in the past years in order to improve the management of waste waters or to reduce deforestation and erosion, the huge challenge of the reduction of cyanobacterial blooms in LV by the control of eutrophication seems far from being achieved.
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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 1568-9883 ISBN Médium
Région Expédition Conférence
Notes WOS:000541912700007 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2822
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Auteur Annasawmy, P.; Cherel, Y.; Romanov, E.; Le Loc'h, F.; Menard, F.; Ternon, J.-F.; Marsac, F.
Titre Stable isotope patterns of mesopelagic communities over two shallow seamounts of the south-western Indian Ocean Type Article scientifique
Année (down) 2020 Publication Revue Abrégée Deep-Sea Res. Part II-Top. Stud. Oceanogr.
Volume 176 Numéro Pages 104804
Mots-Clés biogeochemical provinces; Crustaceans; delta C-13; delta N-15; discrimination factors; feeding ecology; Fish; food-web structure; Micronekton; mozambique channel; particulate organic-matter; Squid; Trophic level; trophic structure; vertical-distribution; water column; yellowfin tuna
Résumé The stable carbon (delta C-13) and nitrogen (delta N-15) isotope values of soft tissues of micronekton (crustaceans, squid, mesopelagic fish) and zooplankton were measured from organisms collected on the RV Antea at two seamounts located in the south-western Indian Ocean: La Perouse (summit depth similar to 60 m) and “MAD-Ridge” (thus named in this study; summit depth similar to 240 m). Surface particulate organic matter (POM-Surf) showed higher delta C-13 at the more productive MAD-Ridge than at the oligotrophic La Perouse seamount. Particulate organic matter and zooplankton were depleted in N-15 at La Pemuse pinnacle compared with MAD-Ridge. Gelatinous organisms and crustaceans occupied the lowest and intermediate tmphic levels (TL similar to 2 and 3 respectively) at both seamounts. Mesopelagic fish and smaller-sized squid sampled at both seamounts occupied TL similar to 3 to 4, whereas the large nektonic squid, Ommastrephes bartramii, collected at MAD-Ridge only, exhibited a TL of similar to 5. The delta N-15 values of common open-water mesopelagic taxa were strongly influenced by specimen size and feeding habits at both seamounts, with an increase in delta N-15 values with increasing size. Carnivorous fish species sampled exclusively over the seamounts' flanks and summits exhibited TL values of similar to 4, irrespective of their wide size ranges. The work could not demonstrate any differences in delta C-13 values of mesopelagic fish between the seamounts and the surrounding oceanic areas. The study segregated clusters of mesopelagic organisms according to their delta C-13 and delta N-15 values, with variations in stable isotope values reflecting a complex range of processes possibly linked to productivity as well as biological and ecological traits of the species (size and feeding mode).
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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 0967-0645 ISBN Médium
Région Expédition Conférence
Notes WOS:000556810400002 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2835
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