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In aquatic ecosystems, light availability can significantly influence microbial turnover of terrestrial organic matter through associated metabolic interactions between phototrophic and heterotrophic communities. However, particularly in streams, microbial functions vary significantly with the structure of the streambed, that is the distribution and spatial arrangement of sediment grains in the streambed. It is therefore essential to elucidate how environmental factors synergistically define the microbial turnover of terrestrial organic matter in order to better understand the ecological role of photoheterotrophic interactions in stream ecosystem processes. In outdoor experimental streams, we examined how the structure of streambeds modifies the influence of light availability on microbial turnover of leaf carbon (C). Furthermore, we investigated whether the studied relationships of microbial leaf C turnover to environmental conditions are affected by flow intermittency commonly occurring in streams. We applied leaves enriched with a C-13-stable isotope tracer and combined quantitative and isotope analyses. We thereby elucidated whether treatment induced changes in C turnover were associated with altered use of leaf C within the microbial food web. Moreover, isotope analyses were combined with measurements of microbial community composition to determine whether changes in community function were associated with a change in community composition. In this study, we present evidence, that environmental factors interactively determine how phototrophs and heterotrophs contribute to leaf C turnover. Light availability promoted the utilization of leaf C within the microbial food web, which was likely associated with a promoted availability of highly bioavailable metabolites of phototrophic origin. However, our results additionally confirm that the structure of the streambed modifies light-related changes in microbial C turnover. From our observations, we conclude that the streambed structure influences the strength of photo-heterotrophic interactions by defining the spatial availability of algal metabolites in the streambed and the composition of microbial communities. Collectively, our multifactorial approach provides valuable insights into environmental controls on the functioning of stream ecosystems.
In aquatic ecosystems, light availability can significantly influence microbial turnover of terrestrial organic matter through associated metabolic interactions between phototrophic and heterotrophic communities. However, particularly in streams, microbial functions vary significantly with the structure of the streambed, that is the distribution and spatial arrangement of sediment grains in the streambed. It is therefore essential to elucidate how environmental factors synergistically define the microbial turnover of terrestrial organic matter in order to better understand the ecological role of photo-heterotrophic interactions in stream ecosystem processes. In outdoor experimental streams, we examined how the structure of streambeds modifies the influence of light availability on microbial turnover of leaf carbon (C). Furthermore, we investigated whether the studied relationships of microbial leaf C turnover to environmental conditions are affected by flow intermittency commonly occurring in streams. We applied leaves enriched with a 13C-stable isotope tracer and combined quantitative and isotope analyses. We thereby elucidated whether treatment induced changes in C turnover were associated with altered use of leaf C within the microbial food web. Moreover, isotope analyses were combined with measurements of microbial community composition to determine whether changes in community function were associated with a change in community composition. In this study, we present evidence, that environmental factors interactively determine how phototrophs and heterotrophs contribute to leaf C turnover. Light availability promoted the utilization of leaf C within the microbial food web, which was likely associated with a promoted availability of highly bioavailable metabolites of phototrophic origin. However, our results additionally confirm that the structure of the streambed modifies light-related changes in microbial C turnover. From our observations, we conclude that the streambed structure influences the strength of photo-heterotrophic interactions by defining the spatial availability of algal metabolites in the streambed and the composition of microbial communities. Collectively, our multifactorial approach provides valuable insights into environmental controls on the functioning of stream ecosystems.
School can be regarded as a context for a variety of leisure activities. Especially in all-day schools an increasing amount of young adolescents is spending more time in extracurricular activities. Therefore, all-day schools hold the potential to produce an "educational surplus" because it is argued that these activities contribute to the psychosocial development of adolescents. However, prior to the quest for possible developmental outcomes which could be related to extracurricular activities, another fundamental question must be responded to: Which groups of these young people do actually participate in such after-school programs? While analysing the socio-economic structure of participants for different school-organised activities, the article follows this query. For reasons of comparability, two other leisure contexts are examined: Clubs and volunteer associations as organised contexts on the one hand and a variety of informal and unstructured leisure activities on the other hand. The results reveal that extracurricular activities in schools succeed in including socially disadvantaged adolescents. The study is based on a secondary analysis of the German PISA 2000 data set.
Wie Gesellschaften Wohlfahrt organisieren und institutionalisieren, drückt ihre grundlegenden Wertvorstellungen über gutes Zusammenleben aus.
Der Vergleich von Gesellschaften lässt sich besonders fruchtbar mit dem Konzept der Wohlfahrtsregime durchführen, das die Logiken der Produktion und Verteilung von Wohlfahrt ins Zentrum stellt und mit dem Regimebegriff die zeitliche Entwicklung durch Regierungsphasen mit einer bestimmten politischen Ausrichtung thematisiert. Deshalb werden aufgrund einer Auseinandersetzung mit der sozialphilosophischen Diskussion acht Performanzkriterien entwickelt, die als Maßstab für den Vergleich von 28 Ländern und fünf Wohlfahrtsregimen verwendet werden: Wohlstand und Wachstum; ökologische Nachhaltigkeit; Innovation; soziale Sicherung durch Unterstützungsleistungen im Risikofall sowie vorsorgend durch Bildungsinvestitionen; Anerkennung der Besonderheiten (Frauenfreundlichkeit und Migrantenfreundlichkeit); Gleichheit der Teilhabe; soziale Integration; Autonomie („freedom of choice and capabilities”).
Anschließend wird der Umbau der Wohlfahrtsregime anlässlich der aktuellen Herausforderungen und Randbedingungen für die verschiedenen Wohlfahrtsregime diskutiert. Schließlich wird untersucht, welche Gruppen in welchen Ländern welche der sechs Wohlfahrtskonzepte unterstützen, die sich bei der Faktorenanalyse von internationalen Einstellungssurveys ergeben.