Control of biofilm-dwelling ciliate communities by temperature and resources

Laboratory and field-related experimental approaches were combined to investigate the impacts of temperature and resource enhancements on the development of biofilm-dwelling ciliate communities. The first part of this study concentrated on ciliate community responses towards experimental warming. It was shown that temperature increase during winter can significantly accelerate the early colonization of biofilms by ciliates and enhance the organism density when the resource supply is sufficient. This can also result in the formation of significantly altered ciliate communities in consequence to temperature increases. In contrast, temperature increase during summer reduces the carrying capacity of biofilms for ciliates when the resource density is low. This finding was confirmed by the results of an experiment with cross-manipulations (temperature- and resource enhancements), in which the negative effect of warming was buffered by supplemental resources The second part of this work concentrated on the responses of biofilm-dwelling ciliate communities towards resource enhancements from two different origins, namely benthic and planktonic bacteria. It was shown that ciliate community responses towards benthic bacteria enrichments are often limited, whereas the ciliates can generally profit from planktonic bacteria enhancements. Such stimulation could either occur directly by the enhancement of suspension-feeding ciliates at especially high temperatures, whereas indirect ciliate community responses were detected, especially at low temperatures. Here, their enhancement was coupled to a previous enhancement of suspension-feeding heterotrophic flagellates, which in return were grazed upon by ciliates. The magnitude of responses strongly depended on the seasonal conditions with regards to both the environmental setting as well as to the presence or absence of ciliate consumers (micrometazoa). The latter finding was also confirmed for pre-grown, mature ciliate communities. Taken together, the different aspects of this study demonstrated that when considered separately, both factors (i.e. temperature and resource density) can significantly affect the development and the structure of biofilm-dwelling ciliate communities. However, the magnitude of community responses towards manipulations of either factor was tightly coupled to the environmental conditions with particular regards to the ambient resource load (in the experiments with temperature enhancements) and to the ambient water temperature (in the experiments with resource enhancements). This demonstrates that temperature and resource availability interactively control the development and the structure of biofilm-dwelling ciliate field communities. Admittedly, ciliate community responses to environmental changes can be hidden due to grazer activities. Although, the assumption of community responses towards environmental changes always has to consider the environmental background (temperature, resource availability, grazer activity) besides of shifts in particular variables

Integrated modelling of social-ecological systems for climate change adaptation

Analysis of climate change risks in support of policymakers to set effective adaptation policies requires an innovative yet rigorous approach towards integrated modelling (IM) of social-ecological systems (SES). Despite continuous advances, IM still faces various challenges that span through both unresolved methodological issues as well as data requirements. On the methodological side, significant improvements have been made for better understanding the dynamics of complex social and ecological systems, but still, the literature and proposed solutions are fragmented. This paper explores available modelling approaches suitable for long-term analysis of SES for supporting climate change adaptation (CCA). It proposes their classification into seven groups, identifies their main strengths and limitations, and lists current data sources of greatest interest. Upon that synthesis, the paper identifies directions for orienting the development of innovative IM, for improved analysis and management of socio-economic systems, thus providing better foundations for effective CCA

Increasing flood risk awareness and warning readiness by participation – But who understands what under ‘participation’?

Participation is an often-demanded process in disaster risk reduction (DRR). However, it is often unclear who understands what under this term. International organizations such as the United Nations have promoted participation in their DRR strategies since the 1980s, but further research is needed on its opportunities and limitations. Here we highlight what is understood by participation according to different actors and various international contexts. This study was motivated by a workshop where flood-risk and resilience experts from 14 countries perceived the nature of participation and the lack of its implementation differently. To unravel the multitude of these perspectives, 27 expert interviews were conducted in seven countries: Belgium, Germany, Indonesia, Iran, Nepal, Pakistan and Peru between March and August 2020. Results show that constraints on the conduction of participation are not only related to the specific country context but differ even within countries. Limitations such as capacities and willingness to participate as well as the role and importance of participation are common issues across the investigated contexts and countries

Auswirkung von Weidedegradation auf die Zusammensetzung und Funktion mikrobieller Gemeinschaften in Böden des Tibetischen Plateaus

Das Tibetische Plateau, mit seinen Kobresia pygmea Weiden, stellt eine globale Senke für organischen Kohlenstoff (OC) dar. Überweidung führt zur Zerstörung der Kobresia Wurzelmatten und damit zur Graslanddegradation. Dies hat massive OC Verluste und die Destabilisierung des Ökosystems zur Folge. Diese Arbeit analysiert den Effekt der degradationsbedingten veränderten Zusammensetzung der organischen Bodensubstanz (SOM) auf die Zusammensetzung der mikrobiellen Gemeinschaft und deren Funktion entlang einer Sequenz von sechs Degradationsstufen. Dazu wurden die Aktivitäten von sechs extrazellulären Enzyme gemessen sowie die Zusammensetzung der bakteriellen und pilzlichen Gemeinschaft (mittels t-RFLP Analyse gefolgt von Illumina MiSeq Sequenzierung) analysiert. So konnte die Zusammensetzung der mikrobiellen Gemeinschaft mit den vertikalen Gradienten der δ13C und δ15N-Werte, sowie den Neutralzucker-, Cutin-, Suberin- und Ligningehalten in Beziehung gesetzt werden. Mit zunehmender Degradation deuten negativere δ13C-Werte auf eine relative Anreicherung an 13C-armen Makromolekülen wie bspw. Lignin hin. Zusammen mit ebenfalls verringerten δ15N-Werten und veränderten C/N-Verhältnissen belegt dies einen verstärkten SOM-Abbau. Gleichzeitig nimmt die Aktivität von hydrolytischen Enzymen, mit fortschreitender Degradation zu. Lediglich in der letzten Degradationsstufe ist ein drastischer Rückgang der Aktivität dieser Enzymgruppe zu beobachten. Im Gegensatz dazu zeigen Phenoloxidasen (Mineralisation komplexer SOM) zunehmende Aktivitäten mit steigender Degradation die mit einer Anreicherung dieser Substrate (z.B. Ligin) einhergeht. Die beobachteten Änderungen der Enzymaktivitäten sind mit einer veränderten Zusammensetzung der mikrobiellen Gemeinschaft, besonders des Unterbodens, begleitet. So nehmen Actinobacteria mit der Degradation ab während Nitrosomonas zunehmenden, was einen steigenden Verlust von mineralisiertem N aus dem Boden erklärt. Bis jetzt ist unklar ob die degradationsbedingten funktionellen und strukturellen Veränderungen der mikrobiellen Gemeinschaft der Kobresia Grasländer reversibel sind, oder ob mit steigendem Verlust an Nährstoffen und Boden ein Punkt erreicht wird, der eine Erholung der Kobresia-Matten nicht mehr erlaubt

Substratum-dependent responses of ciliate assemblages to temperature: a natural experiment in Icelandic streams

Ciliate assemblages play a significant role in the microbial food web. The effects of environmental temperature on assemblage composition may be influenced by abiotic factors such as seasonality and disturbance, but the effects of temperature on ciliate assemblages found on different substrata have not been explored. Sandy bottoms and submerged rocks harbour dissimilar ciliate assemblages, and it might be expected that their ciliate assemblages will respond differently to temperature. We studied how alpha diversity, beta diversity and total biomass of ciliate protist assemblages found on sandy bottoms and submerged rocks differed in 13 geothermally heated streams in Iceland whose mean temperatures range from 5 to 20 °C. We recorded number of operational taxonomic units (OTUs) and measured the size of cells in ciliate assemblages from both substrata. Effects of temperature on natural ciliate assemblages were substratum dependent. On rock surfaces, both total ciliate biomass and alpha diversity declined with increasing temperature, and beta diversity increased with increasing temperature difference due to OTU nestedness (assemblages from warm streams being composed chiefly of subsets of the OTUs found in colder streams). In sandy substrata, however, ciliate assemblage composition was independent of temperature. Substratum-specific responses may be due to differences in mechanical disturbance, nutrient availability or exposure to invertebrate grazers. Rock-surface assemblages may be more exposed to the flow and retain less nutrient than those of sandy substratum; thus, they may be more strongly resource limited and more responsive to direct effects of temperature on metabolism. Alternatively, rock-surface assemblages may be more exposed to grazing by invertebrates, which intensifies with temperature. Our study highlights the need to account for environmental context such as substratum type to fully understand the effect of temperature on microbial assemblages in streams. Future increases in global temperatures may affect fresh waters differently depending on their prevalent substratum. Those dominated by hard substrata may have their ciliate assemblages, and thus, food-web structures and ecosystem functioning more strongly affected by warming relative to systems dominated by soft substrata

Coping with Temperature at the Warm Edge – Patterns of Thermal Adaptation in the Microbial Eukaryote Paramecium caudatum

Ectothermic organisms are thought to be severely affected by global warming since their physiological performance is directly dependent on temperature. Latitudinal and temporal variations in mean temperatures force ectotherms to adapt to these complex environmental conditions. Studies investigating current patterns of thermal adaptation among populations of different latitudes allow a prediction of the potential impact of prospective increases in environmental temperatures on their fitness.In this study, temperature reaction norms were ascertained among 18 genetically defined, natural clones of the microbial eukaryote Paramecium caudatum. These different clones have been isolated from 12 freshwater habitats along a latitudinal transect in Europe and from 3 tropical habitats (Indonesia). The sensitivity to increasing temperatures was estimated through the analysis of clone specific thermal tolerances and by relating those to current and predicted temperature data of their natural habitats. All investigated European clones seem to be thermal generalists with a broad thermal tolerance and similar optimum temperatures. The weak or missing co-variation of thermal tolerance with latitude does not imply local adaptation to thermal gradients; it rather suggests adaptive phenotypic plasticity among the whole European subpopulation. The tested Indonesian clones appear to be locally adapted to the less variable, tropical temperature regime and show higher tolerance limits, but lower tolerance breadths.Due to the lack of local temperature adaptation within the European subpopulation, P. caudatum genotypes at the most southern edge of their geographic range seem to suffer from the predicted increase in magnitude and frequency of summer heat waves caused by climate change

The response of temperate aquatic ecosystems to global warming: novel insights from a multidisciplinary project

This article serves as an introduction to this special issue of Marine Biology, but also as a review of the key findings of the AQUASHIFT research program which is the source of the articles published in this issue. AQUASHIFT is an interdisciplinary research program targeted to analyze the response of temperate zone aquatic ecosystems (both marine and freshwater) to global warming. The main conclusions of AQUASHIFT relate to (a) shifts in geographic distribution, (b) shifts in seasonality, (c) temporal mismatch in food chains, (d) biomass responses to warming, (e) responses of body size, (f) harmful bloom intensity, (f), changes of biodiversity, and (g) the dependence of shifts to temperature changes during critical seasonal windows

Vulnerability and resilience as trends in risk science : a reconstruction of their quantitative and qualitative development in risk science and its perspectives from 1973 until 2017 on the basis of a multidisciplinary internet analysis

Die Konzepte Vulnerabilität und Resilienz stehen im Fokus der wissenschaftlichen und praktischen Diskussion um Risiko und (Un-)Sicherheit. Jedoch ist man sich bis jetzt seitens der Risikoforschung und auch des Risikomanagements uneinig über ihre inhaltliche Bedeutung und ihren Nutzen für eine problemgerechte Risikobehandlung. Bisherige Aufbereitungen der Konzept-Karrieren sowie der unterschiedlichen Verständnisse und Anwendungen in Forschung und Management beziehen sich allein auf einzelne Anwendungsfelder, wie z.B. Katastrophenvorsorge und Klimawandelanpassung und gehen auf quantitative und inhaltliche Entwicklungen der Konzepte nicht detailliert ein. Diese Forschungslücken adressierend, führt diese Dissertation die quantitativ-zeitliche und qualitativ-inhaltliche Diffusion von Vulnerabilität und Resilienz als Trends der Risikoforschung und ihren Perspektiven von 1973 bis 2017 detailliert und systematisch zusammen. Dies erlaubt zudem den Vergleich der quantitativen und qualitativen Diffusion der Konzepte in den verschiedenen Risikoperspektiven sowie die Untersuchung des Einflusses externer katastrophaler Ereignisse und allgemeiner wissenschaftlicher Trends wie Interdisziplinarität, Transdisziplinarität und Formalisierung auf diese Diffusion sowie der Einflussnahme von einigen Perspektiven auf die Konzept-Diffusion in anderen. Diese Dissertation unterstützt die Risikoforschung und das Risikomanagement insbesondere im Kontext der zunehmenden Inter- und Transdisziplinarität von Risikobetrachtungen. Zum einen bietet sie wissenschaftlichen und praktischen Akteuren für die Konzepte Vulnerabilität und Resilienz eine systematische Orientierung innerhalb ihrer konzeptionellen Komplexität, ein verbessertes Verständnis ihrer quantitativen und qualitativen Entwicklung und Verbreitung in den verschiedenen Risikoperspektiven sowie Möglichkeiten für ihre lösungsorientierte Nutzung und praktische Umsetzung. Zum anderen deutet diese Dissertation Grundmuster von Diskursverläufen an, deren Verständnis auch den Umgang mit zukünftigen Trends im Bereich von Risiko und Sicherheit verbessern kann.The concepts of vulnerability and resilience are in the focus of academic and practical discussions concerning risk and security. However, actors in risk research and risk management still disagree about the concepts’ meanings and their relevance for the handling of risk. In this regard a various amount of scientific analyses discusses the career of these concepts and their divergent comprehensions and applications in research and management but only concentrate on specific fields of application like disaster risk reduction and climate change adaptation, or illustrate recent conceptual differences only via a short overview. Addressing these research gaps, this dissertation systematically examines the quantitative-temporal and qualitative-content-wise diffusion of vulnerability and resilience as trends in risk science and its perspectives from 1973 until 2017. Moreover, this approach allows the comparison of the temporal and content-wise concepts’ diffusion in the different perspectives as well as a reflection of a possible influence of external catastrophic events and overall scientific trends like interdisciplinarity, transdisciplinarity and formalisation on that diffusion and of the influence of some risk perspectives on others in the diffusion process. This dissertation is of special relevance for risk research and risk management in context of the growing inter- and transdisciplinarity of risk approaches. On the one hand, it offers scientific and practical experts in context of vulnerability and resilience a systematic orientation within the concepts’ conceptual complexity, an improved understanding of their quantitative and qualitative development in the different risk perspectives as well as options for a more efficient use of both concepts in risk handling and a simplified transfer of scientific comprehensions into practical management approaches. On the other hand, this dissertation suggests specific patterns of scientific discourses which can support scientific and practical actors in dealing with future trends in the field of risk and security

Resource quantity and seasonal background alter warming effects on communities of biofilm ciliates

The impacts of experimental warming on field-related communities of biofilm ciliates were studied in contrasting seasons (winter vs. summer), which incorporated both different species sets and environmental background conditions. The biofilms for the experiments were cultivated in river bypass systems that were exposed to increasing temperatures based on the ambient river temperature. Opposing effects of warming were observed for ciliate 'summer' and 'winter' communities. While winter warming resulted in both stimulation (abundance and biomass) of the ciliate communities and significant shifts in the community structure, summer warming induced a significant decline in the ciliate biomass, but did not affect the relative community composition. By the simultaneous manipulation of temperature and resource density in summer, it was demonstrated that negative warming effects on the ciliate quantity during summer could be compensated by increasing the availability of food. Taken together, our results indicate that the responses of ciliate communities towards warming are strongly coupled to the availability of resources, and that the strongest impacts of environmental warming should thus be expected in resource-rich environments

Interdisziplinäre Perspektiven des Risiko- und Krisenmanagements. Beiträge aus Wissenschaft und Praxis im Rahmen der Veranstaltungsreihe „Risky Monday“

Das Institut für Rettungsingenieurwesen und Gefahrenabwehr der Technischen Hochschule Köln veranstaltet seit November 2014 die abendliche Vortragsreihe „Risky Monday“, in der Experten aus Wissenschaft und Praxis verschiedene Ansätze, Themen und Denkweisen des interdisziplinären Risiko- und Krisenmanagements präsentieren So erlangen unsere Zuhörer neben Einblicke in gesellschaftliche und technische Aspekte des nationalen Bevölkerungsschutzes und der internationalen humanitären Hilfe, auch Wissen über die zugrunde liegenden konzeptionellen und wissenschaftlichen Ansätze. Die vorliegende Ausgabe bietet einen Überblick über die bis zum Wintersemester 2015/2016 stattgefundenen Vorträge, die beruflichen Hintergründe der Vortragenden und Möglichkeiten für Kooperationen im Rahmen von Bachelor- oder Masterarbeiten. Darüber hinaus finden sich in dieser Ausgabe Diskussionsbeiträge der Vortragenden zu Notfall- und Krisenmanagement in Verwaltungsbehörden, psychosozialer Unterstützung und Stakeholder-Beteiligung in der Katastrophenvorsorge