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Auteur McKenzie, D.J.; Vergnet, A.; Chatain, B.; Vandeputte, M.; Desmarais, E.; Steffensen, J.F.; Guinand, B.
Titre Physiological mechanisms underlying individual variation in tolerance of food deprivation in juvenile European sea bass, Dicentrarchus labrax Type Article scientifique
Année 2014 Publication Revue Abrégée Journal of Experimental Biology
Volume (down) 217 Numéro 18 Pages 3283-3292
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Résumé Although food deprivation is a major ecological pressure in fishes, there is wide individual variation in tolerance of fasting, whose mechanistic bases are poorly understood. Two thousand individually tagged juvenile European sea bass were submitted to two ‘fasting/feeding’ cycles each comprising 3 weeks of food deprivation followed by 3 weeks of ad libitum feeding at 25°C. Rates of mass loss during the two fasting periods were averaged for each individual to calculate a population mean. Extreme fasting tolerant (FT) and sensitive (FS) phenotypes were identified that were at least one and a half standard deviations, on opposing sides, from this mean. Respirometry was used to investigate two main hypotheses: (1) tolerance of food deprivation reflects lower mass-corrected routine metabolic rate (RMR) in FT phenotypes when fasting, and (2) tolerance reflects differences in substrate utilisation; FT phenotypes use relatively less proteins as metabolic fuels during fasting, measured as their ammonia quotient (AQ), the simultaneous ratio of ammonia excretion to RMR. There was no difference in mean RMR between FT and FS over 7 days fasting, being 6.70±0.24 mmol h−1 fish−1 (mean ± s.e.m., N=18) versus 6.76±0.22 mmol h−1 fish−1 (N=17), respectively, when corrected to a body mass of 130 g. For any given RMR, however, the FT lost mass at a significantly lower rate than FS, overall 7-day average being 0.72±0.05 versus 0.90±0.05 g day−1 fish−1, respectively (P<0.01, t-test). At 20 h after receiving a ration equivalent to 2% body mass as food pellets, ammonia excretion and simultaneous RMR were elevated and similar in FT and FS, with AQs of 0.105±0.009 and 0.089±0.007, respectively. At the end of the period of fasting, ammonia excretion and RMR had fallen in both phenotypes, but AQ was significantly lower in FT than FS, being 0.038±0.004 versus 0.061±0.005, respectively (P<0.001, t-test). There was a direct linear relationship between individual fasted AQ and rate of mass loss, with FT and FS individuals distributed at opposing lower and upper extremities, respectively. Thus the difference between the phenotypes in their tolerance of food deprivation did not depend upon their routine energy use when fasting. Rather, it depended upon their relative use of tissue proteins as metabolic fuels when fasting, which was significantly lower in FT phenotypes.
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 773
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Auteur Killen, S.S.; Marras, S.; McKenzie, D.J.
Titre Fast growers sprint slower: effects of food deprivation and re-feeding on sprint swimming performance in individual juvenile European sea bass Type Article scientifique
Année 2014 Publication Revue Abrégée Journal of Experimental Biology
Volume (down) 217 Numéro 6 Pages 859-865
Mots-Clés Compensatory growth; Ecophysiology; Food deprivation; Foraging; Locomotion; atlantic; catch-up growth; cod; dicentrarchus-labrax; ecological performance; gadus-morhua; long-term starvation; metabolic responses; salmon; teleost fish; trade-off; trade-offs; trout oncorhynchus-mykiss
Résumé While many ectothermic species can withstand prolonged fasting without mortality, food deprivation may have sublethal effects of ecological importance, including reductions in locomotor ability. Little is known about how such changes in performance in individual animals are related to either mass loss during food deprivation or growth rate during re-feeding. This study followed changes in the maximum sprint swimming performance of individual European sea bass, Dicentrarchus labrax, throughout 45 days of food deprivation and 30 days of re-feeding. Maximum sprint speed did not show a significant decline until 45 days of food deprivation. Among individuals, the reduction in sprinting speed at this time was not related to mass loss. After 30 days of re-feeding, mean sprinting speed had recovered to match that of control fish. Among individuals, however, maximum sprinting speed was negatively correlated with growth rate after the resumption of feeding. This suggests that the rapid compensatory growth that occurs during re-feeding after a prolonged fast carries a physiological cost in terms of reduced sprinting capacity, the extent of which shows continuous variation among individuals in relation to growth rate. The long-term repeatability of maximum sprint speed was low when fish were fasted or fed a maintenance ration, but was high among control fish fed to satiation. Fish that had been previously food deprived continued to show low repeatability in sprinting ability even after the initiation of ad libitum feeding, probably stemming from variation in compensatory growth among individuals and its associated negative effects on sprinting ability. Together, these results suggest that food limitation can disrupt hierarchies of maximum sprint performance within populations. In the wild, the cumulative effects on locomotor capacity of fasting and re-feeding could lead to variable survival among individuals with different growth trajectories following a period of food deprivation.
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ISSN 0022-0949 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 601
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Auteur Wang, T.; Lefevre, S.; Iversen, N.K.; Findorf, I.; Buchanan, R.; McKenzie, D.J.
Titre Anaemia only causes a small reduction in the upper critical temperature of sea bass: is oxygen delivery the limiting factor for tolerance of acute warming in fishes? Type Article scientifique
Année 2014 Publication Revue Abrégée Journal of Experimental Biology
Volume (down) 217 Numéro 24 Pages 4275-4278
Mots-Clés aerobic scope; cardiac-performance; Cardiovascular; climate-change; dicentrarchus-labrax; ecology; exp. biol. 216; fish; Haematocrit; metabolism; Oxygen transport; phenylhydrazine-induced anemia; thermal tolerance; trout
Résumé To address how the capacity for oxygen transport influences tolerance of acute warming in fishes, we investigated whether a reduction in haematocrit, by means of intra-peritoneal injection of the haemolytic agent phenylhydrazine, lowered the upper critical temperature of sea bass. A reduction in haematocrit from 42 +/- 2% to 20 +/- 3% (mean +/- s.e.m.) caused a significant but minor reduction in upper critical temperature, from 35.8 +/- 0.1 to 35.1 +/- 0.2 degrees C, with no correlation between individual values for haematocrit and upper thermal limit. Anaemia did not influence the rise in oxygen uptake between 25 and 33 degrees C, because the anaemic fish were able to compensate for reduced blood oxygen carrying capacity with a significant increase in cardiac output. Therefore, in sea bass the upper critical temperature, at which they lost equilibrium, was not determined by an inability of the cardio-respiratory system to meet the thermal acceleration of metabolic demands.
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Notes <p>ISI Document Delivery No.: AW7BT<br/>Times Cited: 1<br/>Cited Reference Count: 44<br/>Wang, Tobias Lefevre, Sjannie Iversen, Nina K. Findorf, Inge Buchanan, Rasmus McKenzie, David J.<br/>Centre National de la Recherche Scientifique (CNRS); Danish Research Council; Region Languedoc-Roussillon (RLR); Ambassade de France in Copenhagen; Universite Montpellier 2<br/>This research was supported by the Centre National de la Recherche Scientifique (CNRS), the Danish Research Council, The Ambassade de France in Copenhagen and Universite Montpellier 2. T.W. was supported by a fellowship from Region Languedoc-Roussillon (RLR) as a visiting professor at Universite Montpellier 2. I.F. and N.K.I. were supported by a student grant from The Ambassade de France in Copenhagen.<br/>Company of biologists ltd<br/>Cambridge</p> Approuvé pas de
Numéro d'Appel MARBEC @ alain.herve @ collection 1181
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Auteur Chu, T.V.; Torréton, J.-P.; Mari, X.; Nguyen, H.M.T.; Pham, K.T.; Pham, T.T.; Bouvier, T.; Bettarel, Y.; Pringault, O.; Bouvier, C.; Rochelle-Newall, E.
Titre Nutrient ratios and the complex structure of phytoplankton communities in a highly turbid estuary of Southeast Asia Type Article scientifique
Année 2014 Publication Revue Abrégée Environ Monit Assess
Volume (down) 186 Numéro 12 Pages 8555-8572
Mots-Clés Hab; Phytoplankton diversity; Southeast Asia; vietnam
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ISSN 0167-6369 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 1161
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Auteur Canard, E.F.; Mouquet, N.; Mouillot, D.; Stanko, M.; Miklisova, D.; Gravel, D.
Titre Empirical Evaluation of Neutral Interactions in Host-Parasite Networks Type Article scientifique
Année 2014 Publication Revue Abrégée American Naturalist
Volume (down) 183 Numéro 4 Pages 468-479
Mots-Clés abundance; animal mutualistic networks; community; dissimilarity; effort; food-web structure; geographical variation; host-parasite network; network structure; neutrality; null model; phylogenetic signal; reconciling niche; sampling; scale-dependence; species abundance distribution
Résumé While niche-based processes have been invoked extensively to explain the structure of interaction networks, recent studies propose that neutrality could also be of great importance. Under the neutral hypothesis, network structure would simply emerge from random encounters between individuals and thus would be directly linked to species abundance. We investigated the impact of species abundance distributions on qualitative and quantitative metrics of 113 host-parasite networks. We analyzed the concordance between neutral expectations and empirical observations at interaction, species, and network levels. We found that species abundance accurately predicts network metrics at all levels. Despite host-parasite systems being constrained by physiology and immunology, our results suggest that neutrality could also explain, at least partially, their structure. We hypothesize that trait matching would determine potential interactions between species, while abundance would determine their realization.
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ISSN 0003-0147 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 573
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