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Auteur Boyd, C.; Grunbaum, D.; Hunt, G.L.; Punt, A.E.; Weimerskirch, H.; Bertrand, S. doi  openurl
  Titre Effects of variation in the abundance and distribution of prey on the foraging success of central place foragers Type Article scientifique
  Année 2017 Publication Revue Abrégée J. Appl. Ecol.  
  Volume (down) 54 Numéro 5 Pages 1362-1372  
  Mots-Clés allocation; ecosystem; fisheries; Guanay Cormorant; guano-producing seabirds; Humboldt Current system; impact; indicators; marine spatial planning; Peruvian Booby; Phalacrocorax bougainvilliorum; predator-prey interactions; prey availability; seabird competition with fisheries; small pelagic fish; Sula variegata; upwelling system; variability  
  Résumé 1. Seabirds and pinnipeds are vulnerable to reductions in prey availability, especially during the breeding season when spatial constraints limit their adaptive capacity. There are growing concerns about the effects of fisheries on prey availability in regions where large commercial fisheries target forage fish. 2. For breeding seabirds and pinnipeds, prey availability depends on a combination of abundance, accessibility, patchiness and distance from the colony. An understanding of the aspects of prey availability that determine foraging success is essential for the design of effective management responses. 3. We used a mechanistic individual-based foraging model based on observed data for two sea-bird species, the Peruvian Booby Sula variegata and Guanay Cormorant Phalacrocorax bougainvilliorum, to simulate the foraging patterns of seabirds feeding on schooling fish. We ran the model over simulated prey fields representing eight possible combinations of high or low prey abundance, shallow or deep prey, and broadly distributed or spatially concentrated prey. 4. The results highlight the importance of the accessibility of prey. Depth distribution was the primary factor determining modelled foraging success for both species, followed by abundance, and then spatial configuration. 5. Synthesis and applications. The individual-based foraging model provides a spatially explicit framework for assessing the effects of fisheries on the foraging success of seabirds and other central place foragers, and for evaluating the potential effectiveness of marine-protected areas and other fisheries management strategies for safeguarding central place foragers in dynamic ecosystems. Our analysis indicates that broad-scale fisheries management strategies that maintain forage fish above critical biomass levels are essential, but may need to be supplemented by targeted actions, such as time-area closures, when environmental conditions lead to low prey abundance or reduce prey accessibility for seabirds or pinnipeds of conservation concern. The individual-based foraging model is adaptable and could be reconfigured for application to other species and systems.  
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  Langue English Langue du Résumé Titre Original  
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  Volume de collection Numéro de collection Edition  
  ISSN 0021-8901 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2192  
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Auteur Quispe-Ccalluari, C.; Tam, J.; Demarcq, H.; Chamorro, A.; Espinoza-Morriberon, D.; Romero, C.; Dominguez, N.; Ramos, J.; Oliveros-Ramos, R. doi  openurl
  Titre An index of coastal thermal effects of El Nino Southern Oscillation on the Peruvian Upwelling Ecosystem Type Article scientifique
  Année 2018 Publication Revue Abrégée Int. J. Climatol.  
  Volume (down) 38 Numéro 7 Pages 3191-3201  
  Mots-Clés climate; coastal index; eastern tropical pacific; enso; Equatorial Pacific Ocean; events; ocean; Peruvian Upwelling Ecosystem; sea-surface temperature; wind  
  Résumé The Peruvian Upwelling Ecosystem (PUE) is one of the most productive ecosystem in the world in terms of productivity and fish catches, partly because its geographical location is affected by remote physical processes, such as the interannual climate variability of the Equatorial Pacific Ocean (EPO), whose dominant signal is El Nino Southern Oscillation (ENSO). In order to assess the thermal effects of ENSO off Peru, a Peruvian Coastal Thermal Index (PCTI) was developed representing 87.7% of the total variation of the Sea Surface Temperature (SST) anomalies of the PUE. Between 1982 and 2014, the PCTI detected 12 warm periods and 16 cold periods in the PUE. PCTI had a linear trend component, a low frequency component and a noise component, with 1.5%, 94.5% and 4% contributions to the total variance, respectively. Wavelet analysis of PCTI showed significant peaks of variability between the years 1996 and 1999 between periods of 0.4 and 6 years. A regime shift in variance of PCTI was detected in 1999, with a lower variance between 1999 and 2014 than between 1982 and 1998, which agreed with the start of a cold phase of the Pacific Decadal Oscillation. The decrease of variance of the PCTI could be linked to an increase of the local winds associated with a higher intensity of the average state of South Pacific Anticyclone. This atmospheric change might have strengthened the coastal upwelling and counteracted the intensity of warm periods in the PUE. Finally, the comparison of different indexes allowed to detect four periods where neutral conditions occurred in the EPO while warm periods occurred in the PUE (1993, 2008, 2012 and 2014); and 1 period where a warm episode occurred in the EPO (2004-2005) while a neutral condition occurred in the PUE.  
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  Volume de collection Numéro de collection Edition  
  ISSN 0899-8418 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2391  
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Auteur Kirkman, S.P.; Blamey, L.; Lamont, T.; Field, J.G.; Bianchi, G.; Huggett, J.A.; Hutchings, L.; Jackson-Veitch, J.; Jarre, A.; Lett, C.; Lipinski, M.R.; Mafwila, S.W.; Pfaff, M.C.; Samaai, T.; Shannon, L.J.; Shin, Y.-J.; van der Lingen, C.D.; Yemane, D. doi  openurl
  Titre Spatial characterisation of the Benguela ecosystem for ecosystem-based management Type Article scientifique
  Année 2016 Publication Revue Abrégée Afr. J. Mar. Sci.  
  Volume (down) 38 Numéro 1 Pages 7-22  
  Mots-Clés agulhas system; atlantic-ocean; biology; drivers; ecosystem approach to fisheries; large marine ecosystem; large marine ecosystem; marine spatial planning; models; monitoring; northern benguela; nursery areas; physical oceanography; regime shifts; sea use management; southern benguela; upwelling system; variability  
  Résumé The three countries of the Benguela Current Large Marine Ecosystem (BCLME), namely Angola, Namibia and South Africa, have committed to implementing ecosystem-based management (EBM) including an ecosystem approach to fisheries (EAF) in the region, to put in practice the principles of sustainable development in ocean-related matters. There is also recognition of the need for marine spatial planning (MSP) as a process for informing EBM with regard to the allocation and siting of ocean uses so that ecosystem health is ensured and trade-offs between ecosystem services are appropriately dealt with. Marine spatial planning is both an integrated and an area-based process, and this paper produces a spatial characterisation of the BCLME for achieving a common basis for MSP in the region, focusing on the oceanography, biology and fisheries. Recognising spatial variation in physical driving forces, primary and secondary production, trophic structures and species richness, four different subsystems are characterised: (1) north of the Angola-Benguela Front, (2) from the Angola-Benguela Front to Luderitz, (3) from Luderitz to Cape Agulhas, and (4) from Cape Agulhas to Port Alfred on the south-east coast of South Africa. Research and monitoring requirements of relevance for MSP and EBM in the region are identified, focusing on understanding variability and change, including with regard to the boundary areas identified for the system. To this end, 14 cross-shelf monitoring transects are proposed (including seven that are already being monitored) to estimate fluxes of biota, energy and materials within and between the subsystems. The usefulness of models for understanding ecosystem variability and changes is recognised and the need for fine-scale resolution of both sampling and modelling for adequate MSP as input to EBM for the often-conflicting interests of conserving biodiversity, and managing fisheries, recreation, offshore oil and gas exploration and exploitation, offshore mining and shipping routes, is emphasised.  
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  Langue English Langue du Résumé Titre Original  
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  Volume de collection Numéro de collection Edition  
  ISSN 1814-232x ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 1658  
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Auteur Diankha, O.; Ba, A.; Brehmer, P.; Brochier, T.; Sow, B.A.; Thiaw, M.; Gaye, A.T.; Ngom, F.; Demarcq, H. url  doi
openurl 
  Titre Contrasted optimal environmental windows for both sardinella species in Senegalese waters Type Article scientifique
  Année 2018 Publication Revue Abrégée Fisheries Oceanography  
  Volume (down) 27 Numéro 4 Pages 351-365  
  Mots-Clés recruitment success; Sardinella aurita; Sardinella maderensis; upwelling; West Africa  
  Résumé We investigate Sardinella aurita and Sardinella maderensis recruitment success relative to the variability of oceanographic conditions in Senegalese waters using generalized additive models (GAM). Results show that recruitment of both species is marked by a strong intra-annual (seasonal) variation with minimum and maximum in winter and summer, respectively. Their interannual variations are synchronous until 2006 (recruitment decreasing), while from 2007 there is no synchrony. The model developed shows that sardinella recruitment variability is closely related to the tested environmental variables in the study area. However, the key environmental variables influencing the recruitment success are different for both species: the Coastal Upwelling Index and the sea surface temperature for S. aurita and S. maderensis, respectively. We report that recruitment success of S. aurita and S. maderensis are associated with distinct ranges of sea surface temperature, upwelling intensity, wind-induced turbulence, concentration of chlorophyll-a and north Atlantic oscillation index. Considering food security and socio-economic importance of both stocks, we recommend that consideration is given to the environmental variability in the small pelagic fish national management plans, particularly in the context of climate change.  
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  Langue en Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 1365-2419 ISBN Médium  
  Région Expédition Conférence  
  Notes Approuvé pas de  
  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2374  
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Auteur Machu, E.; Ettahiri, O.; Kifani, S.; Benazzouz, A.; Makaoui, A.; Demarcq, H. url  doi
openurl 
  Titre Environmental control of the recruitment of sardines (Sardina pilchardus) over the western Saharan shelf between 1995 and 2002 : a coupled physical/biogeochemical modelling experiment Type Article scientifique
  Année 2009 Publication Revue Abrégée Fisheries Oceanography  
  Volume (down) 18 Numéro 5 Pages 287-300  
  Mots-Clés biomass; Canary upwelling; hydrodynamic and biogeochemical modelling; plankton; potential spawning habitat; recruitment; Sardina pilchardus  
  Résumé Fisheries constitute an important economic sector for Morocco, where the species Sardina pilchardus represents the main landings. In acoustic evaluations conducted along the Moroccan coast since 1995, the absence of juveniles in 1996 and 1998 and the collapse of the sardine stock between 1996 and 1997 represent the main events until 2002. Sardines are known to be microphageous planktivores and thus are sensitive to environmental variability. A biogeochemical model coupled to a hydrodynamic model (ROMS) was run over the Canary Current System (1991-2002) to investigate the environmental factors that could have played a role in the variability of the sardine spawning. A grid refinement (1/12 degrees) centred on the Saharan Bank (SB) region was built to study the main spawning ground of sardines off northwest Africa. The volume of the potential spawning habitat (PSH) of sardines was defined as a function of depth, temperature and salinity, which are included in the ranges 0-200 m, 15-21 degrees C and 35.8-36.8, respectively. Our modelling frame was able to reproduce the seasonal cycle of temperature, phytoplankton concentration and PSH over the SB. It also captured the warming associated with the negative index of the North Atlantic Oscillation of 1995-1997 and allowed a description of the inter-annual variability of the PSH. Our experiment shows that the volume of PSH was much reduced in 1996 compared to the other years. The results suggest that the delay between high abundance of plankton and favourable spawning conditions is a good proxy for determining the recruitment failure of sardine in this oceanic region.  
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  ISSN 1054-6006 ISBN Médium  
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  Numéro d'Appel LL @ pixluser @ collection 43  
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