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Auteur Vieira de Assuncao, R.; Silva, A.C.; Roy, A.; Bourles, B.; Silva, C.H.S.; Ternon, J.-F.; Araujo, M.; Bertrand, A.
Titre 3D characterisation of the thermohaline structure in the southwestern tropical Atlantic derived from functional data analysis of in situ profiles Type Article scientifique
Année 2020 Publication (up) Revue Abrégée Prog. Oceanogr.
Volume 187 Numéro Pages 102399
Mots-Clés barrier layers; Barrier layer; decadal changes; Mixed layer; mixed-layer; North Brazilian Undercurrent system; ocean; Ocean stratification; salinity; seasonal-variations; south-atlantic; thermocline; Thermocline; water masses; western boundary circulation; Western boundary current
Résumé The dynamic of the thermohaline structure of the upper ocean, which depends on ocean-atmosphere interactions, drives most near surface oceanic processes, including the control of gases and heat fluxes, and nutrient availability in the photic layer. The thermohaline structure of the southwestern tropical Atlantic (SWTA), a key region for diagnosing variation of the Atlantic Meridional Overturning Circulation, has prime impact on global climate. Characterising the thermohaline structure is typically based on the application of classical statistical methods on vertical profiles. Such approach has important limitations since classical methods do not explicitly contemplate the vertical nature of the profiles. Functional Data Analysis (FDA) is a new alternative to solve such drawbacks. Here, we apply an FDA approach to characterise the 3D canonical thermohaline structure of the SWTA in austral spring and fall. Our results reveal a clear spatial pattern with the presence of three areas with significantly different thermohaline structure. Area 1, mostly located along the continental slope, reflects the western boundary current system, with low static stability and high frequency of occurrence of barrier layer (BL). Conversely, Area 2, located along the Fernando de Noronha chain, presents strong static stability with a well-marked thermocline. This area, under the influence of the eastern Atlantic, is characterised by a low BL frequency, which is seasonally modulated by the latitudinal oscillation of the Intertropical Convergence Zone, controlling the regime of precipitation. In turn, Area 3 behaves as a transition zone between A1 and A2 with the presence of the water core of maximum salinity in subsurface, and therefore presence of strong-moderate BL. Beyond this study, FDA approach emerges as a powerful way to describe, characterise, classify and compare ocean patterns and processes. It can be applied to in situ data but could also be used to deeply and comprehensively explore ocean model output.
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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 0079-6611 ISBN Médium
Région Expédition Conférence
Notes WOS:000572347900003 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2897
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Auteur Eduardo Nole, L.; Bertrand, A.; Mincarone, M.M.; Santos, L.; Fredou, T.; Assuncao, R.; Silva, A.; Menard, F.; Schwamborn, R.; Le Loc'h, F.; Lucena-Fredou, F.
Titre Hatchetfishes (Stomiiformes: Sternoptychidae) biodiversity, trophic ecology, vertical niche partitioning and functional roles in the western Tropical Atlantic Type Article scientifique
Année 2020 Publication (up) Revue Abrégée Prog. Oceanogr.
Volume 187 Numéro Pages 102389
Mots-Clés Brazil; central equatorial atlantic; diet; Diet; Dissolved oxygen; feeding patterns; Gelatinous organisms; Mesopelagic; mesopelagic fishes; midwater fish; Oceanic islands; organic-matter; Seamounts; Stable isotope composition; stable-isotopes; stomiid pisces; yellowfin tuna; zooplankton
Résumé Species of the family Sternoptychidae (hatchetfishes) occur worldwide and play critical roles by sequestering carbon, recycling nutrients, and acting as a key trophic link between epipelagic primary consumers and higher trophic levels in marine ecosystems. Nevertheless, basic knowledge on their ecology is still lacking and their functional ecology remains understudied with respect to composition, organization, functions and environment interactions. Here we integrated comprehensive information collected in the western Tropical Atlantic on the diversity, abundance, distribution and trophic ecology of hatchetfishes, including physicochemical features of their habitats and extensive carbon and nitrogen stable isotope data on its main prey groups. On this basis we defined five functional groups of hatchetfishes with different diet preference, isotopic composition, and vertical abundance peaks and reveal a possible high resource partitioning. Additionally, these species might have a different feeding tie chronology. Hence, hatchetfishes segregate in different ecological groups responding differently to environmental constraints including oxygen concentration and presenting diverse functional roles. As deep-sea species that migrate to epipelagic waters, hatchetfishes may play a key role in the transfer of subsurface photoassimilated carbon to deeper waters, a pathway through which the effects of climate change at the surface are transferred to the deep ocean. Moreover, as consumers of gelatinous organisms, these species convert “gelatinous energy” into “fish energy” readily usable by higher trophic levels, including endangered and commercially important species. This is a crucial trophic relationship that has been historically underestimated due to methodology limitations (e.g., quickly digested gelatinous organisms were probably underestimated in previous studies, based solely on stomach contents). Considering in ecosystem models this trophic relationship, as well as the functional organization of hatchetfishes, is important to properly answer key ecological questions including resource use, carbon transportation, and influence of mesopelagic community in climate change process.
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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 0079-6611 ISBN Médium
Région Expédition Conférence
Notes WOS:000572347900002 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2898
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Auteur Escalle, L.; Gaertner, D.; Chavance, P.; Delgado de Molina, A.; Ariz, J.; Mérigot, B.
Titre Consequences of fishing moratoria on catch and bycatch: the case of tropical tuna purse-seiners and whale and whale shark associated sets Type Article scientifique
Année 2016 Publication (up) Revue Abrégée Biodivers. Conserv.
Volume 25 Numéro 9 Pages 1637-1659
Mots-Clés atlantic-ocean; Before-after analysis; dolphin; dynamics; fisheries; impacts; management; Marine megafauna; Monte Carlo simulation; mortality; Purse-seine fishery; strategies; time; Time-area regulation
Résumé Time-area regulations have been introduced to manage stocks of tropical tuna, given the increased use of drifting fish aggregation devices (FADs). However, the consequences in terms of changes in fishing strategies and effort reallocation may not always be as expected. For instance, in the eastern Pacific Ocean, previous studies have highlighted that the increase use of FAD-fishing following the demand for tuna caught without dolphin mortality has raised concerns about the bycatch and the capture of juvenile tuna. In the tropical eastern Atlantic and western Indian Oceans, this study aimed to (1) assess, using before-after analysis, the consequences of previous time-area regulations on FAD sets on the fishing effort allocated to megafauna associated sets, and (2) evaluate through Monte Carlo simulations the potential effect of new regulations banning whale or/and whale shark associated sets. Firstly, we showed that previous time-area regulations, which were mainly implemented during seasons with few whale and whale shark associated sets, generally had thus little effect on the number of megafauna associated sets. Secondly, some simulations, particularly when both whale and whale shark associated sets were banned, predicted consequences of changes in fishing strategy. Indeed, these types of ban could lead to an increase in the number of FAD and free school sets but no change in the tuna catch, as well as a slight decrease in bycatch. These results indicate that an ecosystem approach to fisheries, by taking into account megafauna associated sets and bycatch, should thus be adopted when implementing management or conservation measures.
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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 0960-3115 ISBN Médium
Région Expédition Conférence
Notes Approuvé pas de
Numéro d'Appel MARBEC @ alain.herve @ collection 1640
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Auteur Alfonso, S.; Gesto, M.; Sadoul, B.
Titre Temperature increase and its effects on fish stress physiology in the context of global warming Type Article scientifique
Année 2020 Publication (up) Revue Abrégée J. Fish Biol.
Volume Numéro Pages
Mots-Clés acclimation temperature; adaptive capacity; antarctic fish; atlantic salmon; climate-change; coping; cortisol; european sea bass; fresh-water; heat; heat-shock proteins; plasticity; rainbow-trout; teleost; thermal-stress; water temperature
Résumé The capacity of fishes to cope with environmental variation is considered to be a main determinant of their fitness and is partly determined by their stress physiology. By 2100, global ocean temperature is expected to rise by 1-4 degrees C, with potential consequences for stress physiology. Global warming is affecting animal populations worldwide through chronic temperature increases and an increase in the frequency of extreme heatwave events. As ectotherms, fishes are expected to be particularly vulnerable to global warming. Although little information is available about the effects of global warming on stress physiology in nature, multiple studies describe the consequences of temperature increases on stress physiology in controlled laboratory conditions, providing insight into what can be expected in the wild. Chronic temperature increase constitutes a physiological load that can alter the ability of fishes to cope with additional stressors, which might compromise their fitness. In addition, rapid temperature increases are known to induce acute stress responses in fishes and might be of ecological relevance in particular situations. This review summarizes knowledge about effects of temperature increases on the stress physiology of fishes and discusses these in the context of global warming.
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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 0022-1112 ISBN Médium
Région Expédition Conférence
Notes WOS:000588735000001 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2920
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Auteur Eduardo Nole, L.; Lucena-Fredou, F.; Mincarone, M.M.; Soares, A.; Le Loc'h, F.; Fredou, T.; Menard, F.; Bertrand, A.
Titre Trophic ecology, habitat, and migratory behaviour of the viperfish Chauliodus sloani reveal a key mesopelagic player Type Article scientifique
Année 2020 Publication (up) Revue Abrégée Sci Rep
Volume 10 Numéro 1 Pages 20996
Mots-Clés atlantic bluefin tuna; carbon transport; feeding ecology; fish assemblage; northeast atlantic; pisces stomiidae; southern tasmania; species composition; thunnus-thynnus; vertical-distribution
Résumé Mesopelagic fishes are numerically the most important vertebrate group of all world's oceans. While these species are increasingly threatened by anthropogenic activities, basic biological knowledge is still lacking. For instance, major uncertainties remain on the behaviour, ecology, and thus functional roles of mesopelagic micronektivores, particularly regarding their interactions with physicochemical features. Here, we examine the trophic ecology, habitat, and migratory behaviour of the viperfish (Chauliodus sloani)-a poorly known and abundant deep-sea species-to further understand the ecology and thus functional role of mesopelagic micronektivores. Moreover, we explore how physical drivers may affect these features and how these relationships are likely to change over large oceanic areas. The viperfish heavily preys on epipelagic migrant species, especially myctophids, and presents spatial and trophic ontogenetic shifts. Temperature restricts its vertical distribution. Therefore, its trophodynamics, migratory behaviour, and functional roles are expected to be modulated by the latitudinal change in temperature. For instance, in most tropical regions the viperfish stay full-time feeding, excreting, and serving as prey (e.g. for bathypelagic predators) at deep layers. On the contrary, in temperate regions, the viperfish ascend to superficial waters where they trophically interact with epipelagic predators and may release carbon where its remineralization is the greatest.
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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 2045-2322 ISBN Médium
Région Expédition Conférence
Notes WOS:000600427300001 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2933
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