Résultats des exploitations ovines en France. Un constat à partir du RICA

The decrease of mutton production in France and the difficulties of breeders during a few last years make necessary the analysis of sheep farms economic situation.La baisse de la production de viande ovine en France et les difficultés des éleveurs au cours des dernières années rendent nécessaire l'analyse de la situation économique des exploitations ayant un élevage ovin pour la viande.Causeret François, Chaalali A. Résultats des exploitations ovines en France. Un constat à partir du RICA. In: Économie rurale. N°198, 1990. p. 15

Climate-Caused Abrupt Shifts in a European Macrotidal Estuary

International audienceAlthough many consequences of climate change on marine and terrestrial ecosystems are well documented, the characterisation of estuarine ecosystems specific responses and the drivers of the changes are less understood. In this study, we considered the biggest Southwestern European estuary, the Gironde, as a model of a macrotidal estuary to assess the effects of both large- (i.e., North Atlantic basin-scale) and regional-scale climate changes. Using a unique set of data on climatic, physical, chemical and biological parameters for the period 1978–2009, we examined relations between changes in both the physical and chemical environments and pelagic communities (plankton and fish) via an end-to-end approach. Our results show that the estuary experienced two abrupt shifts (!1987 and !2000) over the last three decades, which altered the whole system. The timing of these abrupt shifts are in accordance with abrupt shifts reported in both marine (e.g., in the North Sea, the Mediterranean Sea and along the Atlantic) and terrestrial (e.g., in European lakes) realms. Although this work does not allow a full understanding of the dynamical processes through which climate effects propagate along the different compartments of the ecosystem, it provides evidence that the dynamics of the largest estuary of Southwest Europe is strongly modulated by climate change at both regional and global scales

LONG-TERM ENVIRONMENTAL CHANGES IN THE GIRONDE ESTUARY

participantThe Gironde estuary is considered the largest South-Western European estuary and covers an area of 625 km2 at high tide. This transition zone between marine and freshwater environments is formed by the junction of the Garonne and the Dordogne rivers. The Gironde is characterized by a strong spatiotemporal variability of environmental parameters, modulating biological response. While most studies deal with the impact of anthropogenic pressures on estuaries, this research aims at understanding and distinguishing the part of variability that can be explained by human local activities from those that is linked to Climate Change. Using data from the ecological monitoring of the Blayais nuclear power plant, this research contributes to better know the estuarine evolution over the last thirty years. This paper presents the chemical, physical and climatic parameters changes by characterizing global and local trends, interannual variability and an eventual periodicity using different data analyses (i.e. linear regression, moving average, and eigenvectors filtering). Then, correlations between environmental parameters were analyzed and the potential influence of climate variability was evaluated with a standardized Principal Component Analysis

Reaction of an estuarine food web to disturbance: Lindeman’s perspective

Abstract Currently, a central demand of coastal and marine food web researchers is the search for holistic and functional ecosystem health indicators. Based on concepts directly derived from R. L. Lindeman’s work (Lindeman 1942; Ecology 23:399–418), 6 estuarine food web models were analysed to assess the potential impact of multiple disturbances on the trophic state of food webs. The models described a Zostera noltii meadow and a bare sediment site in the Mondego estuary, Portugal, during 3 distinct time periods corresponding to (1) nutrient enrichment, (2) the implementation of mitigation measures, and (3) after a centenary flood. We tested 4 candidate metrics, directly derived from the trophic-dynamic concepts proposed by Lindeman (1942): food chain length, the detritivory/herbivory ratio, trophic efficiency per trophic level and mean trophic efficiency. Based on this case study, none of the metrics are yet ready to be used per se as operational metrics to quantify and interpret the impact of disturbances on the ecosystem’s trophic state. Trophic efficiency appeared to be sensitive to external pressures. However, the mean trophic efficiency of the system might not be sufficient to draw conclusions about the trophic efficiency of the ecosystem: trophic efficiency should be observed at the trophic level in order to better understand cascading effects within food webs

Les petits pélagiques dans l'estuaire de la Gironde : 30 ans de suivi d'abondance face à 30 ans de changements globaux

National audienceLes conséquences écologiques du changement global (changement climatique + pressions anthropiques) ont été montrées pour les communautés écologiques de l'estuaire de la Gironde dans plusieurs études récentes. La marinisation et le réchauffement de l'eau, principaux effets, entrainent de profondes modifications dans la structure et la dynamique des communautés ichtyologiques. Cependant, ces récentes études sur les poissons notamment, n'ont pas explicitement montré le lien entre les facteurs environnementaux et les réponses des communautés. Objectifs : caractériser explicitement les modifications de structure et de dynamique temporelle des poissons pélagiques et le lien avec les facteurs environnementaux

Reaction of an estuarine food web to disturbance: Lindeman's perspective

Currently, a central demand of coastal and marine food web researchers is the search for holistic and functional ecosystem health indicators. Based on concepts directly derived from R. L. Lindeman's work (Lindeman 1942; Ecology 23:399-418), 6 estuarine food web models were analysed to assess the potential impact of multiple disturbances on the trophic state of food webs. The models described a Zostera noltii meadow and a bare sediment site in the Mondego estuary, Portugal, during 3 distinct time periods corresponding to (1) nutrient enrichment, (2) the implementation of mitigation measures, and (3) after a centenary flood. We tested 4 candidate metrics, directly derived from the trophic-dynamic concepts proposed by Lindeman (1942): food chain length, the detritivory/herbivory ratio, trophic efficiency per trophic level and mean trophic efficiency. Based on this case study, none of the metrics are yet ready to be used per se as operational metrics to quantify and interpret the impact of disturbances on the ecosystem's trophic state. Trophic efficiency appeared to be sensitive to external pressures. However, the mean trophic efficiency of the system might not be sufficient to draw conclusions about the trophic efficiency of the ecosystem: trophic efficiency should be observed at the trophic level in order to better understand cascading effects within food webs. © Inter-Research 201

Specific physical trainability in elite young soccer players: efficiency over 6 weeks’ in-season training

The aim of the present study was to compare the effects of 3 training protocols (plyometric [PLYO], agility [AG], or repeated shuttle sprints [RS]) on physical performance in the same population of young soccer players. Forty-two youth-level male players (13.6±0.3-years; 1.65±0.07 m; 54.1±6.5 kg; body fat: 12.8±2.6%) participated in a short-term (6-week) randomized parallel fully controlled training study (pre-to-post measurements): PLYO group, n=10; AG group, n=10; RS group, n=12; and control group [CON] n=10. PLYO training = 9 lower limb exercises (2-3 sets of 8-12 repetitions). The AG group performed planned AG drills and direction changes. RS training consisted of 2-4 sets of 5-6x 20 to 30 m shuttle sprints (20 seconds recovery in between). Progressive overload principles were incorporated into the programme by increasing the number of foot contacts and varying the complexity of the exercises. Pre/post-training tests were: bilateral standing horizontal jump, and unilateral horizontal jumps, sprint (30 m with 10 m lap time), agility (20 m zigzag), and repeated sprint ability (RSA) (i.e. 6x30 m shuttle sprints: 2x15 m with 180° turns). Significant main effects for time (i.e. training application) and group (training type) were detected. Improvements in horizontal jumping were higher (p<0.01: ES=large) in PLYO. The RS group improved significantly more (p<0.01; ES=large) than other groups: 30 m sprint, RSAbest and RSAmean performances. Significantly greater increases in 20 m zigzag performance were observed following AG and RS training (4.0 and 3.8%, respectively) compared with PLYO (2.0%) and CON training (0.8%). No significant differences were reported in the RSAdec between groups. Elite young male soccer players’ physical performances can be significantly and specifically improved either using PLYO or AG or RSA training over short-term in-season training

Reaction of an estuarine food web to disturbance: Lindeman’s perspective

International audienceCurrently, a central demand of coastal and marine food web researchers is the search for holistic and functional ecosystem health indicators. Based on concepts directly derived from R. L. Lindeman’s work (Lindeman 1942; Ecology 23:399–418), 6 estuarine food web models were analysed to assess the potential impact of multiple disturbances on the trophic state of food webs. The models described a Zostera noltii meadow and a bare sediment site in the Mondego estuary, Portugal, during 3 distinct time periods corresponding to (1) nutrient enrichment, (2) the implementation of mitigation measures, and (3) after a centenary flood. We tested 4 candidate metrics, directly derived from the trophic-dynamic concepts proposed by Lindeman (1942): food chain length, the detritivory/herbivory ratio, trophic efficiency per trophic level and mean trophic efficiency. Based on this case study, none of the metrics are yet ready to be used per se as operational metrics to quantify and interpret the impact of disturbances on the ecosystem’s trophic state. Trophic efficiency appeared to be sensitive to external pressures. However, the mean trophic efficiency of the system might not be sufficient to draw conclusions about the trophic efficiency of the ecosystem: trophic efficiency should be observed at the trophic level in order to better understand cascading effects within food webs