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| Auteur |
Stier, A.; Viblanc, V.A.; Massemin-Challet, S.; Handrich, Y.; Zahn, S.; Rojas, E.R.; Saraux, C.; Le Vaillant, M.; Prud'homme, O.; Grosbellet, E.; Robin, J.-P.; Bize, P.; Criscuolo, F. |
| Titre |
Starting with a handicap: phenotypic differences between early- and late-born king penguin chicks and their survival correlates |
Type |
Article scientifique |
| Année |
2014 |
Publication |
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Revue Abrégée |
Functional Ecology |
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corticosterone; early-life conditions; growth; individual quality; oxidative stress; phenotypic plasticity; reproductive timing; telomere |
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* The exceptionally long (c. 11 months) growth period of king penguin chicks (Aptenodytes patagonicus) is interrupted by the Austral winter. As a consequence, penguin chicks born late in the breeding season have little time to build-up their energy reserves before the drastic energy bottleneck they experience during winter and face greater risks of mortality than early-born chicks. * Whereas it is well known that breeding adults alternate between early- and late-breeding attempts, little is known on the phenotype of early- and late-chicks, and on the potential existence of specific adaptive phenotypic responses in late-born individuals. * We investigated phenotypic differences between early- and late-chicks and tested their survival correlates both before the winter and at fledgling. Chicks were sampled 10 days after hatching to measure body mass, plasma corticosterone levels, oxidative stress parameters and telomere length. * Late-chicks were heavier than early-chicks at day 10. Late-chicks also had higher corticosterone and oxidative stress levels, shorter telomere lengths and suffered from higher mortality rates than early-chicks. For both early- and late-chicks, high body mass close to hatching was a strong predictor of survival up to, and over, the winter period. * In late but not early-chicks, high corticosterone levels and long telomeres were significant predictors of survival up to winter and fledging, respectively. * Our study provides evidence that late- and early-king penguin chicks showed marked phenotypic differences 10 days after hatching. We provide an integrative discussion on whether these differences may be adaptive or not, and to what extent they may be driven by active maternal effects, indirectly induced by environmental effects, or stem from individual differences in parental quality. |
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1365-2435 |
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LL @ pixluser @ |
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319 |
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Neira, S.; Moloney, C.; Christensen, V.; Cury, P.; Shannon, L.; Arancibia, H. |
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Analysing changes in the southern Humboldt ecosystem for the period 1970-2004 by means of dynamic food web modelling |
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Article scientifique |
| Année |
2014 |
Publication |
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Revue Abrégée |
Ecological Modelling |
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274 |
Numéro |
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Pages |
41-49 |
| Mots-Clés |
Ecopath with Ecosim; Fishing patterns; Physical forcing; Regime shifts; Southern Humboldt; Trophic controls |
| Résumé |
A 22-group Ecopath model representing the southern Humboldt (SH) upwelling system in the year 1970 is constructed. The model is projected forward in time and fitted to available time series of relative biomass, catch and fishing mortality for the main fishery resources. The time series cover the period 1970 to 2004 and the fitting is conducted using the Ecopath with Ecosim (EwE) software version 5.1. The aim is to explore the relative importance of internal (trophic control) and external (fishing, physical variability) forcing on the dynamics of commercial stocks and the Southern Chilean food web. Wide decadal oscillations are observed in the biomass of commercial stocks during the analyzed period. Fishing mortality explains 21% of the variability in the time series, whereas vulnerability (v) parameters estimated using EwE explain an additional 20%. When a function affecting primary production (PP) is calculated by Ecosim to minimize the sum of squares of the time series, a further 28% of variability is explained. The best fit is obtained by using the fishing mortality time series and by searching for the best combination of v parameters and the PP function simultaneously, accounting for 69% of total variability in the time series. The PP function obtained from the best fit significantly correlates with independent time series of an upwelling index (UI; rho = 0.47, p<0.05) and sea surface temperature (SST; rho = -0.45, p<0.05), representing environmental conditions in the study area during the same period of time. These results suggest that the SH ecosystem experienced at least two different environmentally distinct periods in the last three decades: (i) from 1970 to 1985 a relatively warm period with low levels of upwelling and PP, and (ii) from 1985 to 2004 a relatively cold period with increased upwelling and PP. This environmental variability can explain some of the changes in the food webs. Fishing (catch rate) and the environment (bottom-up anomaly in PP) appear to have affected the SH both at the stock and at the food web level between 1970 and 2004. The vulnerability setting indicates that the effects of external forcing factors may have been mediated by trophic controls operating in the food web. |
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0304-3800 |
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LL @ pixluser @ |
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330 |
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Joo, R.; Bertrand, A.; Bouchon, M.; Chaigneau, A.; Demarcq, H.; Tam, J.; Simier, M.; Gutiérrez, D.; Gutiérrez, M.; Segura, M.; Fablet, R.; Bertrand, S. |
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Ecosystem scenarios shape fishermen spatial behavior. The case of the Peruvian anchovy fishery in the Northern Humboldt Current System |
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Article scientifique |
| Année |
2014 |
Publication |
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Revue Abrégée |
Progress in Oceanography |
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128 |
Numéro |
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60-73 |
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A major goal in marine ecology is the understanding of the interactions between the dynamics of the different ecosystem components, from physics to top predators. While fishermen are among the main top predators at sea, almost none of the existing studies on ecology from physics to top predators contemplate fishermen as part of the system. The present work focuses on the coastal processes in the Northern Humboldt Current System, which encompasses both an intense climatic variability and the largest monospecific fishery of the world. From concomitant satellite, acoustic survey and Vessel Monitoring System data (∼90,000 fishing trips) for a ten-year period (2000–2009), we quantify the associations between the dynamics of the spatial behavior of fishermen, environmental conditions and anchovy (Engraulis ringens) biomass and spatial distribution. Using multivariate statistical analyses we show that environmental and anchovy conditions do significantly shape fishermen spatial behavior and present evidences that environmental fluctuations smoothed out along trophic levels. We propose a retrospective analysis of the study period in the light of the ecosystem scenarios evidenced and we finally discuss the potential use of fishermen spatial behavior as ecosystem indicator. |
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0079-6611 |
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LL @ pixluser @ |
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321 |
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Louati, H.; Ben Said, O.; Soltani, A.; Cravo-Laureau, C.; Preud'Homme, H.; Duran, R.; Aissa, P.; Mahmoudi, E.; Pringault, O. |
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Impacts of bioremediation schemes for the mitigation of a low-dose anthracene contamination on free-living marine benthic nematodes |
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Article scientifique |
| Année |
2014 |
Publication |
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Revue Abrégée |
Ecotoxicology |
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23 |
Numéro |
2 |
Pages |
201-212 |
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Anthracene; Bioremediation; Community structure; Free-living nematodes; Meiofauna; bacteria; biodegradation; bizerte lagoon; degrading; laboratory microcosm experiment; microcosm experiment; oil-spills; photoinduced toxicity; polycyclic aromatic-hydrocarbons; sediments |
| Résumé |
A microcosm experiment was used to examine (1) the effects of different bioremediation schemes on degradation of anthracene and the structure of free-living marine nematodes in a lightly contaminated (4.5 mu g g(-1)) sediment from Bizerte lagoon and (2) the responses of the nematode community upon an artificial spiking of a low dose anthracene (1 mu g g(-1)). For that purpose sediment microcosms were incubated in laboratory for 40 days. Bioremediation techniques decreased the anthracene contamination, and interestingly, biodegradation were more efficient when anthracene was artificial supplied into the sediment suggesting that the addition of bioavailable anthracene stimulated the bacterial community to adjust towards a PAH-degrading community. Spiking with this low dose of anthracene provoked significant changes in the nematode community structure and abundance, with the elimination of specific species such as Mesacanthion diplechma, the decrease of the dominant species Oncholaimus campylocercoides and the increase in abundance of opportunistic species such as Spirinia parasitifera. This would suggest a low tolerance of the nematode community despite the presence of a weak anthracene contamination in the sediment that could have allow dominance of an anthracene tolerant nematode species. Anthracene toxicity was alleviated in biostimulation treatments, leading to a strong increase in nematode abundance, concomitantly with changes in the nematode community structure; Prochromadorella neapolitana became the most abundant species. |
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English |
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0963-9292 |
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MARBEC @ isabelle.vidal-ayouba @ |
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657 |
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Ternon, J.-F.; Bach, P.; Barlow, R.; Huggett, J.; Jaquemet, S.; Marsac, F.; Ménard, F.; Penven, P.; Potier, M.; Roberts, M.J. |
| Titre |
The Mozambique Channel : from physics to upper trophic levels |
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Article scientifique |
| Année |
2014 |
Publication |
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Revue Abrégée |
Deep-Sea Research Part II.Topical Studies in Oceanography |
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100 |
Numéro |
No spécial |
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1-9 |
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Biological production; Mesoscale circulation; Mozambique Channel; Multi-disciplinary approach; Physical-biological coupling |
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A multidisciplinary programme, MESOBIO (Influence of mesoscale dynamics on biological productivity at multiple trophic levels in the Mozambique Channel) was undertaken in the Mozambique Channel within the framework of a scientific partnership between France and South Africa. MESOBIO focused on the signature of the highly energetic eddy dynamics in the Mozambique Channel. The Channel, which is known to be one of the most turbulent areas in the world ocean, has a great diversity of marine organisms and is the site of active pelagic fisheries. MESOBIO was mostly based on observations at sea during 12 multidisciplinary cruises between 2002 and 2010. Hydrographic measurements, sampling of biological organisms ranging from phytoplankton to top predators, and experiments on primary production and energy transfer through the food web, were conducted onboard various research vessels. The data were analysed in relation to eddy field characteristics for the periods of the cruises, including seasonal or inter-annual variability in mesoscale activity. A modelling approach was also developed within MESOBIO for both the circulation in the Channel and the biogeochemical response to eddy forcing. This paper introduces the suite of articles on the MESOBIO investigations by summarizing background knowledge for the different disciplines and the key issues that were addressed within the programme. |
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Barlow, R.; Marsac, F.; Ternon, J.-F.; Roberts, M. |
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0967-0645 |
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LL @ pixluser @ |
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371 |
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