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Auteur Lucena-Fredou, F.; Kell, L.; Fredou, T.; Gaertner, D.; Potier, M.; Bach, P.; Travassos, P.; Hazin, F.; Menard, F.
Titre (down) Vulnerability of teleosts caught by the pelagic tuna longline fleets in South Atlantic and Western Indian Oceans Type Article scientifique
Année 2017 Publication Revue Abrégée Deep-Sea Res. Part II-Top. Stud. Oceanogr.
Volume 140 Numéro Pages 230-241
Mots-Clés Bycatch; climate-change; ecological risk-assessment; exploitation status; Fishery management; impact; life-history strategies; management; marine fishes; Productivity and Susceptibility Analysis; risk; Sustainability; trawl fishery
Résumé Productivity and Susceptibility Analysis (PSA) is a methodology for evaluating the vulnerability of a stock based on its biological productivity and susceptibility to fishing. In this study, we evaluated the vulnerability of 60 stocks of tuna, billfishes and other teleosts caught by the tuna longline fleets operating in the South Atlantic and Indian Ocean using a semi-quantitative PSA. We (a) evaluated the vulnerability of the species in the study areas; (b) compared the vulnerability of target and non-target species and oceans; (c) analyzed the sensitivity of data entry; and (d) compared the results of the PSA to other fully quantitative assessment methods. Istiophoridae exhibited the highest scores for vulnerability. The top 10 species at risk were: Atlantic Istiophorus albicans; Indian Ocean Istiompax indica; Atlantic Makaira nigricans and Thunnus alalunga; Indian Ocean Xiphias gladius; Atlantic T. albacares, Gempylus serpens, Ranzania laevis and X. gladius; and Indian Ocean T. alalunga. All species considered at high risk were targeted or were commercialized bycatch, except for the Atlantic G. serpens and R. laevis which.were discarded, and may be considered as a false positive. Those species and others at high risk should be prioritized for further assessment and/or data collection. Most species at moderate risk were bycatch species kept for sale. Conversely, species classified at low risk were mostly discarded. Overall, species at high risk were overfished and/or subjected to overfishing. Moreover, all species considered to be within extinction risk (Critically Endangered, Endangered and Vulnerable) were in the high risk category. The good concordance between approaches corroborates the results of our analysis. PSA is not a replacement for traditional stock assessments, where a stock is assessed at regular intervals to provide management advice. It is of importance, however, where there is uncertainty about catches and life history parameters, since it can identify species at risk, and where management action and data collection is required, e.g. for many species at high and most at moderate risk in the South Atlantic and Indian oceans.
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ISSN 0967-0645 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2179
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Auteur Blasco, F.R.; Esbaugh, A.J.; Killen, S.S.; Rantin, F.T.; Taylor, E.W.; McKenzie, D.J.
Titre (down) Using aerobic exercise to evaluate sub-lethal tolerance of acute warming in fishes Type Article scientifique
Année 2020 Publication Revue Abrégée J. Exp. Biol.
Volume 223 Numéro 9 Pages jeb218602
Mots-Clés capacity; climate-change; CTmax; hypoxia tolerance; marine fishes; Oreochromis niloticus; oxygen-tensions; performance; Piaractus mesopotamicus; scope; sea bass; temperature; thermal tolerance
Résumé We investigated whether fatigue from sustained aerobic swimming provides a sub-lethal endpoint to define tolerance of acute warming in fishes, as an alternative to loss of equilibrium (LOE) during a critical thermal maximum (CTmax) protocol. Two species were studied, Nile tilapia (Oreochromis niloticus) and pacu (Piaractus mesopotamicus). Each fish underwent an incremental swim test to determine gait transition speed (U-GT), where it first engaged the unsteady anaerobic swimming mode that preceded fatigue. After suitable recovery, each fish was exercised at 85% of their own U-GT and warmed 1 degrees C every 30 min, to identify the temperature at which they fatigued, denoted as CTswim. Fish were also submitted to a standard CTmax, warming at the same rate as CTswim, under static conditions until LOE. All individuals fatigued in CTswim, at a mean temperature approximately 2 degrees C lower than their CTmax. Therefore, if exposed to acute warming in the wild, the ability to perform aerobic metabolic work would be constrained at temperatures significantly below those that directly threatened survival. The collapse in performance at CTswim was preceded by a gait transition qualitatively indistinguishable from that during the incremental swim test. This suggests that fatigue in CTswim was linked to an inability to meet the tissue oxygen demands of exercise plus warming. This is consistent with the oxygen and capacity limited thermal tolerance (OCLTT) hypothesis, regarding the mechanism underlying tolerance of warming in fishes. Overall, fatigue at CTswim provides an ecologically relevant sub-lethal threshold that is more sensitive to extreme events than LOE at CTmax.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 0022-0949 ISBN Médium
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Notes WOS:000541842300012 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2817
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Auteur Sardenne, F.; Hollanda, S.; Lawrence, S.; Albert-Arrisol, R.; Degroote, M.; Bodin, N.
Titre (down) Trophic structures in tropical marine ecosystems: a comparative investigation using three different ecological tracers Type Article scientifique
Année 2017 Publication Revue Abrégée Ecol. Indic.
Volume 81 Numéro Pages 315-324
Mots-Clés feeding-behavior; Stable isotopes; food webs; Fatty acids; Mercury; western indian-ocean; gulf-of-mexico; amino-acid; stable-isotope; bioaccumulation; fatty-acid compositions; Indian ocean; mercury exposure; pelagic fishes; Tropical food web
Résumé We looked at how three ecological tracers may influence the characterization and interpretation of trophic structures in a tropical marine system, with a view to informing tracer(s) selection in future trophic ecology studies. We compared the trophic structures described by stable isotope compositions (carbon and nitrogen), the total mercury concentration (THg) and levels of essential fatty acids (EFA) at both the individual and species level. Analyses were undertaken on muscle tissue samples from fish and crustacean species caught in the waters surrounding the Seychelles. The carbon isotope composition (delta C-13) correlated to the proportion of arachidonic acid (ARA), whereas the nitrogen isotope composition (delta N-15) correlated to the proportion of docosahexaenoic acid (DHA) and THg. At the individual level, trophic position obtained with these three last tracers are similar. In ' contrast, the eicosapentaenoic acid (EPA) was not clearly correlated to any of the tracers. At the species level, the use of EFA (ARA and DHA), as compared to stable isotopes, resulted in slight structural modifications, mainly in the middle trophic levels. For example, the EFA overestimated the trophic positions of Thunnus alalunga and Etelis coruscans but underestimated the trophic positions of other snappers and groupers. While ARA mainly originates from coastal/benthic areas, DHA is conserved throughout the food web and may be used as a proxy indicator of trophic position. However, metabolic disparities can affect ecological tracers and in turn, distort the trophic structures derived from their results. This is especially true for species with close trophic ecologies. Despite these caveats, we think that analysing at the individual level the wealth of ARA, DHA and THg data that has already been obtained through earlier nutrition or food security studies would enhance our understanding of trophic structures.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 1470-160x ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2246
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Auteur Blasco, F.R.; McKenzie, D.J.; Taylor, E.W.; Rantin, F.T.
Titre (down) The role of the autonomic nervous system in control of cardiac and air-breathing responses to sustained aerobic exercise in the African sharptooth catfish Clarias gariepinus Type Article scientifique
Année 2017 Publication Revue Abrégée Comp. Biochem. Physiol. A-Mol. Integr. Physiol.
Volume 203 Numéro Pages 273-280
Mots-Clés Adrenergic tone; bass dicentrarchus-labrax; cardiorespiratory interactions; Cholinergic tone; Fishes; Heart rate; heart-rate; hoplerythrinus-unitaeniatus; Hypoxia; oxygen-tensions; rainbow-trout; salmo-gairdneri; Swimming; synbranchus-marmoratus
Résumé Clarias gariepinus is a facultative air-breathing catfish that exhibits changes in heart rate (f(H)) associated with air breaths (AB). A transient bradycardia prior to the AB is followed by sustained tachycardia during breath-hold. This study evaluated air-breathing and cardiac responses to sustained aerobic exercise in juveniles (total length similar to 20 cm), and how exercise influenced variations in f(H) associated with AB. In particular, it investigated the role of adrenergic and cholinergic control in cardiac responses, and effects of pharmacological abolition of this control on air-breathing responses. Sustained exercise at 15, 30 and 45 cm s(-1) in a swim tunnel caused significant increases in f(AB) and f(H), from approximately 5 breaths h(-1) and 60 heartbeats min(-1) at the lowest speed, to over 60 breaths h(-1) and 100 beats min(-1) at the highest, respectively. There was a progressive decline in the degree of variation in f(H), around each AB, as f(AB) increased with exercise intensity. Total autonomic blockade abolished all variation in fH during exercise, and around each AB, but f(AB) responses were the same as in untreated animals. Cardiac responses were exclusively due to modulation of inhibitory cholinergic tone, which varied from >100% at the lowest speed to <10% at the highest. Cholinergic blockade had no effect on f(AB) compared to untreated fish. Excitatory beta-adrenergic tone was approximately 20% and did not vary with swimming speed, but its blockade increased f(AB) at all speeds, compared to untreated animals. This reveals complex effects of autonomic control on air-breathing during exercise in C. gariepinus, which deserve further investigation. (C) 2016 Elsevier Inc. 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 1095-6433 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 1714
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Auteur Leprieur, F.; Oikonomou, A.
Titre (down) The need for richness-independent measures of turnover when delineating biogeographical regions Type Article scientifique
Année 2014 Publication Revue Abrégée Journal of Biogeography
Volume 41 Numéro 2 Pages 417-420
Mots-Clés Beta diversity; bioregionalization; clustering; compositional dissimilarity; freshwater fishes; species richness; species turnover; β-3 index; βsim index
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ISSN 1365-2699 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 896
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