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Auteur Neira, S.; Moloney, C.; Christensen, V.; Cury, P.; Shannon, L.; Arancibia, H. url  doi
openurl 
  Titre (up) Analysing changes in the southern Humboldt ecosystem for the period 1970-2004 by means of dynamic food web modelling Type Article scientifique
  Année 2014 Publication Revue Abrégée Ecological Modelling  
  Volume 274 Numéro 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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  Volume de collection Numéro de collection Edition  
  ISSN 0304-3800 ISBN Médium  
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  Numéro d'Appel LL @ pixluser @ collection 330  
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Auteur Coll, M.; Carreras, M.; Ciércoles, C.; Cornax, M.-J.; Gorelli, G.; Morote, E.; Sáez, R. url  doi
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  Titre (up) Assessing Fishing and Marine Biodiversity Changes Using Fishers' Perceptions: The Spanish Mediterranean and Gulf of Cadiz Case Study Type Article scientifique
  Année 2014 Publication Revue Abrégée PLoS ONE  
  Volume 9 Numéro 1 Pages  
  Mots-Clés  
  Résumé BackgroundThe expansion of fishing activities has intensively transformed marine ecosystems worldwide. However, available time series do not frequently cover historical periods.MethodologyFishers' perceptions were used to complement data and characterise changes in fishing activity and exploited ecosystems in the Spanish Mediterranean Sea and Gulf of Cadiz. Fishers' interviews were conducted in 27 fishing harbours of the area, and included 64 fishers from ages between 20 to >70 years old to capture the experiences and memories of various generations. Results are discussed in comparison with available independent information using stock assessments and international convention lists.Principal FindingsAccording to fishers, fishing activity substantially evolved in the area with time, expanding towards deeper grounds and towards areas more distant from the coast. The maximum amount of catch ever caught and the weight of the largest species ever captured inversely declined with time. Fishers (70%) cited specific fishing grounds where depletion occurred. They documented ecological changes of marine biodiversity during the last half of the century: 94% reported the decline of commercially important fish and invertebrates and 61% listed species that could have been extirpated, with frequent mentions to cartilaginous fish. Declines and extirpations were in line with available quantitative evaluations from stock assessments and international conventions, and were likely linked to fishing impacts. Conversely, half of interviewed fishers claimed that several species had proliferated, such as cephalopods, jellyfish, and small-sized fish. These changes were likely related to trophic cascades due to fishing and due to climate change effects. The species composition of depletions, local extinctions and proliferations showed differences by region suggesting that regional dynamics are important when analysing biodiversity changes.Conclusions/SignificanceUsing fishers' perceptions, fishing and ecological changes in the study area were documented. The recovery of local ecological knowledge provides valuable information complementing quantitative monitoring and evaluation surveys.  
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  Numéro d'Appel LL @ pixluser @ collection 380  
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Auteur PERNET, F.; LAGARDE, F.; LE GALL, P.; ROQUE D'ORBCASTEL, E. url  openurl
  Titre (up) Associations between farming practices and disease mortality of Pacific oyster Crassostrea gigas in a Mediterranean lagoon Type Article scientifique
  Année 2014 Publication Aquaculture Environment Interactions Revue Abrégée  
  Volume 5 Numéro 2 Pages 99-106  
  Mots-Clés Aquaculture; Epidemiology; OsHV-1; Shellfish farming  
  Résumé We present the first large-scale, high-resolution spatial and temporal pattern of disease mortality caused by Ostreid herpesvirus 1 (OsHV-1) that has affected Pacific oyster Crassostrea gigas in France every year since 2008, in relation to local farm use. Mortality was monitored in healthy oyster spat deployed at 106 locations in the Thau Mediterranean lagoon during the epizootic that occurred in spring 2011. We conducted a field survey of farming practices in the areas where the sentinel oysters were placed before the epizootic. We found that the risk of disease mortality in sentinel oysters was higher within the bivalve farming area than outside it, suggesting that the infection pressure is much higher in areas with intensive farming activity. The risk of mortality was higher in farms rearing spat, a developmental stage particularly susceptible to OsHV-1, than in farms rearing adult oysters, which are generally more resistant. Additionally, the mortality risk in farms rearing adult animals was similar to that in empty farms, which suggests that, during the study period, adult oysters did not vector the disease. Interestingly, the mortality risk for sentinel oysters deployed in mussel Mytilus galloprovincialis farms was lower than for those held in oyster farms or empty farms, suggesting that mussels reduced the infection pressure on susceptible oysters.  
  Adresse UMR LEMAR Ifremer CNRS UBO IRD, Technopole Brest Iroise, F-29280 Plouzane, France.  
  Auteur institutionnel Thèse  
  Editeur Inter-research Lieu de Publication Éditeur  
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  ISSN 1869-215x ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ 31248 collection 1217  
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Auteur Monnet, A.C.; Jiguet, F.; Meynard, C.N.; Mouillot, D.; Mouquet, N.; Thuiller, W.; Devictor, V. url  doi
openurl 
  Titre (up) Asynchrony of taxonomic, functional and phylogenetic diversity in birds Type Article scientifique
  Année 2014 Publication Revue Abrégée Global Ecology and Biogeography  
  Volume 23 Numéro 7 Pages 780-788  
  Mots-Clés Beta diversity; Rao; assemblages; beta components; biological diversity; breeding bird survey; climate-change; communities; conservation; evolutionary; functional traits; homogenization; indexes; patterns; species turnover; temporal dynamics  
  Résumé Aim We assessed the temporal trends of taxonomic, functional and phylogenetic diversities in the French avifauna over the last two decades. Additionally, we investigated whether and how this multifaceted approach to biodiversity dynamics can reveal an increasing similarity of local assemblages in terms of species, traits and/or lineages. Location France. Methods We analysed a large-scale dataset that recorded annual changes in the abundance of 116 breeding birds in France between 1989 and 2012. We decomposed and analysed the spatio-temporal dynamics of taxonomic, phylogenetic and functional diversities and each of their -, – and -components. We also calculated the trend in the mean specialization of bird communities to track the relative success of specialist versus generalist species within communities during the same period. Results We found large variation within and among the temporal trends of each biodiversity facet. On average, we found a marked increase in species and phylogenetic diversity over the period considered, but no particular trend was found for functional diversity. Conversely, changes in -diversities for the three facets were characterized by independent and nonlinear trends. We also found a general increase in the local occurrence and abundance of generalist species within local communities. Main conclusions These results highlight a relative asynchrony of the different biodiversity facets occurring at large spatial scales. We show why a multifaceted approach to biodiversity dynamics is needed to better describe and understand changes in community composition in macroecology and conservation biogeography.  
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  Langue English Langue du Résumé Titre Original  
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  Volume de collection Numéro de collection Edition  
  ISSN 1466-822x ISBN Médium  
  Région Expédition Conférence  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 455  
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Auteur Fouilland, E.; Tolosa, I.; Bonnet, D.; Bouvier, C.; Bouvier, T.; Bouvy, M.; Got, P.; Le Floc'h, E.; Mostajir, B.; Roques, C.; Sempéré, R.; Sime-Ngando, T.; Vidussi, F. url  doi
openurl 
  Titre (up) Bacterial carbon dependence on freshly produced phytoplankton exudates under different nutrient availability and grazing pressure conditions in coastal marine waters Type Article scientifique
  Année 2014 Publication Revue Abrégée FEMS microbiology ecology  
  Volume 87 Numéro 3 Pages 757-769  
  Mots-Clés bacteria; carbon coupling; coastal waters; interactions; phytoplankton  
  Résumé The effects of grazing pressure and inorganic nutrient availability on the direct carbon transfer from freshly produced phytoplankton exudates to heterotrophic bacteria biomass production were studied in Mediterranean coastal waters. The short-term incorporation of (1)(3)C (H(1)(3)CO(3)) in phytoplankton and bacterial lipid biomarkers was measured as well as the total bacterial carbon production (BP), viral lysis and the microbial community structure under three experimental conditions: (1) High inorganic Nutrient and High Grazing (HN + HG), (2) High inorganic Nutrient and Low Grazing (HN + LG) and (3) under natural in situ conditions with Low inorganic Nutrient and High Grazing (LN + HG) during spring. Under phytoplankton bloom conditions (HN + LG), the bacterial use of freshly produced phytoplankton exudates as a source of carbon, estimated from (1)(3)C enrichment of bacterial lipids, contributed more than half of the total bacterial production. However, under conditions of high grazing pressure on phytoplankton with or without the addition of inorganic nutrients (HN + HG and LN + HG), the (1)(3)C enrichment of bacterial lipids was low compared with the high total bacterial production. BP therefore seems to depend mainly on freshly produced phytoplankton exudates during the early phase of phytoplankton bloom period. However, BP seems mainly relying on recycled carbon from viral lysis and predators under high grazing pressure.  
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  Langue Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 1574-6941 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 444  
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