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Auteur Saulquin, B.; Fablet, R.; Mercier, G.; Demarcq, H.; Mangin, A.; d' Andon, O.H.F.
Titre Multiscale Event-Based Mining in Geophysical Time Series: Characterization and Distribution of Significant Time-Scales in the Sea Surface Temperature Anomalies Relatively to ENSO Periods from 1985 to 2009 Type Article scientifique
Année 2014 Publication Revue Abrégée IEEE J. Sel. Top. Appl. Earth Observ. Remote Sens.
Volume 7 Numéro 8 Pages (down) 3543-3552
Mots-Clés algorithm; climate-change; Distribution of the sea surface temperature anomalies events related to the ENSO periods; event-based mining in large geophysical datasets (big data); frequency; geophysical time series as series of significant time-scale events; models; monsoon variability; ocean; pacific; patterns; predictability; wavelet analysis
Résumé In this paper, one-dimensional (1-D) geophysical time series are regarded as series of significant time-scale events. We combine a wavelet-based analysis with a Gaussian mixture model to extract characteristic time-scales of 486 144 detected events in the Sea Surface Temperature Anomaly (SSTA) observed from satellite at global scale from 1985 to 2009. We retrieve four low-frequency characteristic time-scales of Nino Southern Oscillation (ENSO) in the 1.5- to 7-year range and show their spatial distribution. High-frequency (HF) SSTA event spatial distribution shows a dependency to the ENSO regimes, pointing out that the ENSO signal also involves specific signatures at these time-scales. These fine-scale signatures can hardly be retrieved from global EOF approaches, which tend to exhibit uppermost the low-frequency influence of ENSO onto the SSTA. In particular, we observe at global scale a major increase by 11% of the number of SSTA HF events during Nino periods, with a local maximum of 80% in Europe. The methodology is also used to highlight an ENSO-induced frequency shift during the major 1997-2000 ENSO event in the intertropical Pacific. We observe a clear shift from the high frequencies toward the 3.36-year scale with a maximum shift occurring 2 months before the ENSO maximum of energy at 3.36-year scale.
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ISSN 1939-1404 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1205
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Auteur Chu, Y.; Tournoud, M.G.; Salles, C.; Got, P.; Perrin, J.L.; Rodier, C.; Caro, A.; Troussellier, M.
Titre Spatial and temporal dynamics of bacterial contamination in South France coastal rivers: focus on in-stream processes during low flows and floods Type Article scientifique
Année 2014 Publication Revue Abrégée Hydrological Processes
Volume 28 Numéro 8 Pages (down) 3300-3313
Mots-Clés Coliforms and streptococci; Mediterranean rivers; faecal indicator loads; flush effect; point sources; riverbed sediment abundance
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ISSN 0885-6087 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 839
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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 217 Numéro 18 Pages (down) 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 Anderson, P.S.L.; Claverie, T.; Patek, S.N.
Titre Levers And Linkages: Mechanical Trade-Offs In A Power-Amplified System Type Article scientifique
Année 2014 Publication Revue Abrégée Evolution
Volume 68 Numéro 7 Pages (down) 1919-1933
Mots-Clés amplification; Biomechanics; comparative methods; evolution; kinematic transmission; labrid fishes; mantis shrimp; modularity; morphology; phylogenetic; stomatopods; strike; trade-offs
Résumé Mechanical redundancy within a biomechanical system (e. g., many-to-one mapping) allows morphologically divergent organisms to maintain equivalent mechanical outputs. However, most organisms depend on the integration of more than one biomechanical system. Here, we test whether coupled mechanical systems follow a pattern of amplification (mechanical changes are congruent and evolve toward the same functional extreme) or independence (mechanisms evolve independently). We examined the correlated evolution and evolutionary pathways of the coupled four-bar linkage and lever systems in mantis shrimp (Stomatopoda) ultrafast raptorial appendages. We examined models of character evolution in the framework of two divergent groups of stomatopods-“smashers” (hammer-shaped appendages) and “spearers” (bladed appendages). Smashers tended to evolve toward force amplification, whereas spearers evolved toward displacement amplification. These findings show that coupled biomechanical systems can evolve synergistically, thereby resulting in functional amplification rather than mechanical redundancy.
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ISSN 0014-3820 ISBN Médium
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Notes <p>ISI Document Delivery No.: AL3TK<br/>Times Cited: 1<br/>Cited Reference Count: 40<br/>Anderson, Philip S. L. Claverie, Thomas Patek, S. N.<br/>National Science Foundation [IOS-1149748]<br/>The authors would like to thank S. Price for extensive assistance on phylogenetic comparative methods and L. Revell for help and advice for using his Phytools package for R. We would also like to thank M. Porter, M. Rosario, P. Green, S. Cox, and K. Kagaya for helpful discussions on stomatopod biology as well as two anonymous reviewers for their insightful comments, which have greatly improved the quality of this article. We also thank K. Reed (National Museum of Natural History, Washington, DC) and S. Keable (Australian Museum of Natural History, Sydney) for access to their specimen collections. This work was funded by the National Science Foundation (IOS-1149748) to SNP. The authors declare no conflict of interest.<br/>Wiley-blackwell<br/>Hoboken</p> Approuvé pas de
Numéro d'Appel MARBEC @ alain.herve @ collection 1156
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Auteur VAN BEVEREN, E.; BONHOMMEAU, S.; FROMENTIN, J.-M.; BIGOT, J.-L.; BOURDEIX, J.-H.; BROSSET, P.; ROOS, D.; SARAUX, C.
Titre Rapid changes in growth, condition, size and age of small pelagic fish in the Mediterranean Type Article scientifique
Année 2014 Publication Marine Biology Revue Abrégée
Volume 161 Numéro 8 Pages (down) 1809-1822
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Résumé Since 2007, the ecosystem of the Gulf of Lions has shifted to a different regime, characterised by a low anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) biomass and a remarkably high sprat (Sprattus sprattus) biomass. Surprisingly, the abundance and recruitment of anchovy and sardine remained high. To understand which processes (bottom-up or top-down control, etc.) could have caused this shift, we studied the changes in body condition, growth and size and age of anchovy, sardine and sprat over 1984–1985 and 1992–2012, using data from scientific surveys. The annual age structure of anchovy and sardine was estimated using Bayesian mixture models based on size frequency data with priors on the age–length relationship derived from independent otolith readings. The results indicated periods during which anchovy and sardine were in an average (1992–2004), good (2005–2007) or poor (2008–2012) overall state of condition. For sardine, the shift towards smaller fish observed during these past 4 years was explained by a combination of slower growth and the disappearance of older individuals (ages 2+). Despite the increase in biomass of sprat since 2008, indications were found that sprat was also smaller than in the past. As growth and condition decreased and overexploitation has not been documented or suspected for those three species in this area, we propose that the current decline in sardine and anchovy biomass could be due to qualitative and/or quantitative modifications in the planktonic production (i.e. a bottom-up control) or mass mortalities of adults due to an epidemic disease.
Adresse Univ Montpellier 2, Res Unit EME UMR 212, F-34203 Sete, France.
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Editeur Springer Lieu de Publication Éditeur
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ISSN 0025-3162 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ 30335 collection 986
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