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Auteur (up) Amossé, J.; Bettarel, Y.; Bouvier, C.; Bouvier, T.; Tran Duc, T.; Doan Thu, T.; Jouquet, P.
Titre The flows of nitrogen, bacteria and viruses from the soil to water compartments are influenced by earthworm activity and organic fertilization (compost vs. vermicompost) Type Article scientifique
Année 2013 Publication Revue Abrégée Soil Biology & Biochemistry
Volume 66 Numéro Pages 197-203
Mots-Clés Bacterial and viral abundance; Bacterial diversity; Compost; Dichogaster bolaui; Earthworms; Leaching; Organic fertilization; Vermicompost
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ISSN 0038-0717 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 892
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Auteur (up) Aubert, A.; Antajan, E.; Lynam, C.; Pitois, S.; Pliru, A.; Vaz, S.; Thibault, D.
Titre No more reason for ignoring gelatinous zooplankton in ecosystem assessment and marine management: Concrete cost-effective methodology during routine fishery trawl surveys Type Article scientifique
Année 2018 Publication Revue Abrégée Mar. Pol.
Volume 89 Numéro Pages 100-108
Mots-Clés scyphomedusae; abundance; climate-change; Monitoring; aurelia-aurita; Gelatinous zooplankton; irish sea; Jellyfish; jellyfish blooms; large medusae; Marine management; msfd; northern california current; spatial overlap; surface waters; Trawl
Résumé Gelatinous zooplankton, including cnidarians, ctenophores, and tunicates (appendicularians, pyrosomes, salps and doliolids), are often overlooked by scientific studies, ecosystem assessments and at a management level. Despite the important economic consequences that they can have on human activities and on the marine food web, arguments often related to the costs of monitoring or their coordination, or simply negligence, have resulted in the absence of relevant monitoring programs. A cost-effective protocol has been applied on trawling from existing fishery surveys conducted by national laboratories in England and France. The testing phase has successfully demonstrated the adequacy of such a tool to sample macro- and mega-zooplankton gelatinous organisms in a cost-effective way. This success has led to the acceptance of this protocol into the French implementation of the EU's Marine Strategy Framework Directive (MSFD). Here, a protocol which can be applied to any trawl-based fishery survey and in any new large-scale monitoring program is provided. As an ecosystem approach to marine management is currently adopted, exemplified by the MSFD in Europe, gelatinous zoo plankton should be monitored correctly to prevent a knowledge gap and bias to ecosystem assessments in future.
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ISSN 0308-597x ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2310
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Auteur (up) Ayon, P.; Swartzman, G.; Espinoza, P.; Bertrand, A.
Titre Long-term changes in zooplankton size distribution in the Peruvian Humboldt Current System : conditions favouring sardine or anchovy Type Article scientifique
Année 2011 Publication Revue Abrégée Marine Ecology. Progress Series
Volume 422 Numéro Pages 211-222
Mots-Clés abundance; anchovy; Current; dominance; energetics; Euphausiids; Feeding; Humboldt; Sardine; size; System; Zooplankton
Résumé Changes in the size distribution of zooplankton in the Humboldt Current System have been hypothesized to underlie observed changes in sardine and anchovy populations, the dominant pelagic fish species. To examine this hypothesis, the size distribution of over 15 000 zooplankton data samples collected since the 1960s was qualitatively determined. Dominance of each size group of zooplankton (small, medium and large) and of euphausiids was modelled using generalized additive models as a function of year, latitude, time of day, distance from the 200 m isobath (a surrogate for on-shelf versus off-shelf), sea surface temperature and salinity. The temporal (yr) pattern for euphausiid dominance was highly cross-correlated (i.e. was in phase) with the time series for estimated biomass of anchovy, and small zooplankton dominance with that for estimated sardine biomass. This supports the focal hypothesis based on feeding-energetic experiments, which showed energetic advantages to sardine filter feeding on smaller zooplankton and to anchovy bite feeding on larger copepods and euphausiids. Although euphausiids predominate offshore from the shelf break, anchovy biomass is generally highest on the shelf, suggesting a possible mismatch between anchovy feeding and euphausiid dominance. However, evidence concerning the offshore expansion of the anchovy range in cooler conditions, where both anchovy and euphausiids predominate, somewhat alleviates this apparent contradiction. A strong diel component to euphausiids and large zooplankton indicated diel migration for these zooplankton groups. That anchovy will preferentially eat euphausiids when they are more available (i.e. during the night and offshore) is supported by anchovy diet data.
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ISSN 0171-8630 ISBN Médium
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Numéro d'Appel LL @ pixluser @ collection 117
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Auteur (up) Ba, A.; Chaboud, C.; Schmidt, J.; Diouf, M.; Fall, M.; Deme, M.; Brehmer, P.
Titre The potential impact of marine protected areas on the Senegalese sardinella fishery Type Article scientifique
Année 2019 Publication Revue Abrégée Ocean Coastal Manage.
Volume 169 Numéro Pages 239-246
Mots-Clés abundance; Aichi targets; Bioeconomic modeling; Fishery management; Fishing capacity; management; mpa; Sardinella aurita; Sardinella maderensis; small pelagic fish; Small scale fisheries; West Africa; west-africa
Résumé In the early 2000s, Senegal set up several Marine Protected Areas (MPAs) along its coastal zone with the purpose of biodiversity conservation and to support sustainable management of fisheries. However, the impact of MPAs may vary according to the type of fisheries. In Senegal, the sardinella fishery accounts for 70% of total catches. This fishery is of crucial importance for national food security and employment. Given this importance, it is necessary to evaluate the impact of MPAs, often being considered as a tool for fisheries management. An analytical, dynamic and spatial bio-economic model of sardinella fishery, considering fish and fisher migration, has been developed and scenarios over forty years have been analyzed. The results show that the fishery is economically overexploited and that Senegal could lose about 11.6 billion CFA over forty years of exploitation, i.e. 290 million CFA per year. To achieve an optimal level of exploitation, it would be necessary to halve the current fishing capacity. Implementing MPAs for 10, 20 and 30% of the Senegalese exclusive economic zone lead to slight increases in biomass (1%) and rent (5-11%). In addition, spatio-temporal closures can lead to increased exploitation in unclosed areas, due to the absence of enforcement. Achieving target 11 of the Aichi Convention, i.e., 10% of coastal and marine areas protected per country, will have a reserve effect on the resource but also only lead to weak improvements in economic indicators for the Senegalese fishery. Finally, because the sardinella resource is shared among many countries of the Sub-Regional Fisheries Commission (SRFC), a sub-regional cooperation is necessary for a sustainable management.
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ISSN 0964-5691 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2536
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Auteur (up) Baidai, Y.; Dagorn, L.; Amande, M.J.; Gaertner, D.; Capello, M.
Titre Machine learning for characterizing tropical tuna aggregations under Drifting Fish Aggregating Devices (DFADs) from commercial echosounder buoys data Type Article scientifique
Année 2020 Publication Revue Abrégée Fish Res.
Volume 229 Numéro Pages 105613
Mots-Clés behavior; classification; communities; Direct abundance indicator; echo-sounder buoys; Echosounder buoys; estimate biomass; fads; Fish aggregating devices; Purse seiner; purse seiners; target strength; temperature; Tropical tunas; yellowfin thunnus-albacares
Résumé The use of echosounder buoys deployed in conjunction with Drifting Fish Aggregating Devices (DFADs) has progressively increased in the tropical tuna purse seine fishery since 2010 as a means of improving fishing efficiency. Given the broad distribution of DFADs, the acoustic data provided by echosounder buoys can provide an alternative to the conventional CPUE index for deriving trends on tropical tuna stocks. This study aims to derive reliable indices of presence of tunas (and abundance) using echosounder buoy data. A novel methodology is presented which utilizes random forest classification to translate the acoustic backscatter from the buoys into metrics of tuna presence and abundance. Training datasets were constructed by cross-referencing acoustic data with logbook and observer data which reported activities on DFADs (tuna catches, new deployments and visits of DFADs) in the Atlantic and Indian Oceans from 2013 to 2018. The analysis showed accuracies of 75 and 85 % for the recognition of the presence/absence of tuna aggregations under DFADs in the Atlantic and Indian Oceans, respectively. The acoustic data recorded at ocean-specific depths (6-45m in the Atlantic and 30-150m in the Indian Ocean) and periods (4 a.m.-4 p.m.) were identified by the algorithm as the most important explanatory variables for detecting the presence of tuna. The classification of size categories of tuna aggregations showed a global accuracy of nearly 50 % for both oceans. This study constitutes a milestone towards the use of echosounder buoys data for scientific purposes, including the development of promising fisheries-independent indices of abundance for tropical tunas.
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ISSN 0165-7836 ISBN Médium
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Notes WOS:000539099200018 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2816
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