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Applying environmental DNA metabarcoding to investigate patterns of Arctic marine biodiversity with a focus on gelatinous zooplankton
No full textThe Arctic is warming at least four times faster than the global average, as a result of anthropogenic climate change. Sea and air temperatures are rising, and perennial sea ice coverage has declined over the last four decades, with ice-free summers predicted to occur before 2050. Furthermore, in the Arctic gateway, Fram Strait, an increasing influence of warm Atlantic water is driving the ‘Atlantification’ of both environmental and biological processes. These changes affect habitat and resource availability for marine species in the region, causing shifts in species distributions and assemblages. There has been an intensification in research targeting the impacts of these changes over the last decades, however, important gaps in baseline knowledge of the current state of Arctic marine biodiversity still remain. The development of environmental DNA (eDNA) metabarcoding techniques has given rise to cost-effective and non-invasive methods for biodiversity assessments. One major advantage of eDNA is that it has the potential to detect delicate or elusive taxa that are typically overlooked or damaged by traditional net sampling, such as gelatinous zooplankton (GZP). This highly diverse group plays major roles across Arctic marine ecosystems. However, gaps in basic ecological data persist, including information on species assemblages and distribution. Thus, the overarching aim of this thesis was to apply eDNA metabarcoding to increase our knowledge of Arctic marine biodiversity, with a focus on GZP ecology.
Environmental DNA signals elucidated well-known vertical structuring of pelagic diversity and community composition in the open ocean (Chapter Two) and in the marginal ice zone (Chapter Three) of Fram Strait. Distinct community assemblages were linked to environmental conditions, which represented different water masses (Chapter Two) and different sea ice and meltwater dynamics (Chapter Three). Finally, significant structuring in community composition was revealed across the inner section of a Svalbard fjord (Chapter Four), based on seawater- and sediment-derived eDNA. These findings demonstrate that eDNA metabarcoding is a valuable tool for investigating the spatial patterns and abiotic drivers of marine biodiversity in the Arctic. It also proved to be a sensitive and accurate method for investigating biodiversity across different spatial scales, habitats, seasons and environmental conditions. It was applied across a large area of the open ocean in Fram Strait during summer, in a sampling scheme that encompassed depths from surface waters down to the bathypelagic (Chapter Two). It was also used to detect fine-scale patterns in the upper meters of the sub-ice water column in the marginal ice zone, during the late summer (Chapter Three). Lastly, it was implemented during the polar night period, in the central section of a semi-enclosed fjord system with high levels of glacier input and water turbidity (Chapter Four).
Additionally, this thesis was able to demonstrate that eDNA metabarcoding is a valuable method for investigating the diversity of GZP in the Arctic Ocean. Comparisons between eDNA and non-DNA-based survey methods (Chapters Two and Four) showed that eDNA recovered the highest numbers of species. It was also evident that each technique had inherent biases, with different GZP communities detected depending on the survey method used. Thus, we were able to confirm that eDNA greatly improves our repertoire for sampling GZP in the Arctic, but a combination of sampling methods should be employed to gain a more accurate picture of the diversity present. Finally, multi-marker analyses were applied (Chapters Three and Five) to further investigate the accuracy of two commonly used universal metabarcoding markers and their associated primers for amplifying common Arctic GZP taxa. The COI gene showed higher taxonomic resolution (e.g., species-level) but was affected by primer mismatches for some groups. The 18S gene was able to amplify more GZP groups, but genus and species-level assignments were not accurate. Therefore, it was evident that both are useful for investigating GZP diversity, but which one to prioritize should be determined by the research question at hand. Finally, it was evident that gaps in reference databases persist for both genes and that filling these with GZP samples from the Arctic should be a priority for future research.
Overall, the research presented in this thesis supports the use of eDNA metabarcoding as a non-invasive and sensitive method for improving our understanding of Arctic marine biodiversity. It shows the utility of eDNA metabarcoding to go beyond presence data and to investigate abiotic drivers of eukaryotic biodiversity in different marine habitats and conditions. Moreover, it highlights the benefits of incorporating eDNA methods into GZP research to better understand how this important, yet understudied group will be affected by ongoing climate change in the Arctic. Finally, this thesis contributes valuable baseline data to our current understanding of marine eukaryotic biodiversity in the Atlantic sector of the Arctic
Physiologische Temperatureffekte in Arktischen Mikroalgen
No full textThe Arctic Ocean is most prone to climate change, which exposes marine organisms to especially high degrees of ocean warming. Phytoplankton, the main primary producers of the Arctic Ocean, experience thermally induced changes in their physiology, and these impacts will likely propagate up the food web and have severe effects on marine biogeochemical cycling. The objective of this dissertation was to unravel how Arctic phytoplankton responds to different warming scenarios with a special emphasis on their underlying physiology. To achieve this, I used a combination of single-strain phytoplankton incubation experiments, including detailed physiological characterizations, and incubation experiments with natural Arctic phytoplankton communities to substantiate overarching temperature responses of phytoplankton physiology also on an ecologically more relevant level.
Publication I aimed to assess temperature response patterns of multiple functional traits in Arctic key phytoplankton species. To this end, I cultivated the centric diatom Thalassiosira hyalina, the mixotrophic picoeukaryote Micromonas pusilla and the ice-algae Nitzschia frigida over a temperature gradient from 0°C to 14°C and measured growth rates, biomass production, quotas of biomass and pigmentation as well as photophysiology. Next to surprisingly high optimal growth temperatures and maximal growth rates in all species, it was found that thermal sensitivities and optimal temperatures varied among species and functional traits. This resulted in distinct temperature response patterns of physiological processes such as cell division and biomass production, with their interplay ultimately shaping distinct temperature response patterns of biomass quotas.
Publication II aimed to identify hypothesized physiological imbalances between photosynthetic and respiratory sub-processes under warming. I further intended to understand how fundamental regulatory mechanisms adjust physiology to explain the high phenotypic plasticity of Arctic phytoplankton in response to increasing temperatures. To this end, I assessed photophysiological characteristics of photosystem II (PSII) as well as gas fluxes of 18O2, 16O2 and CO2 corresponding to photosynthetic O2 production and C-fixation as well as respiratory CO2 release and O2 consumption in T. hyalina at distinct temperatures (2°C, 6°C and 10°C) using fast repetition rate fluorometry (FRRf) and membrane-inlet mass-spectrometry (MIMS). I found two major regulatory strategies of T. hyalina to acclimate to increasing temperatures. First, T. hyalina cells upregulated their light harvesting abilities to compensate for detrimental temperature effects on PSII efficiency, which made cells more prone to light-limitation. Thereby, cells were able to maintain their absolute electron transport rates per PSII, resulting in unchanged O2 production. Second, I found that a metabolic coupling between chloroplasts and mitochondria was essential for cells to dissipate excess reductant towards mitochondrial processes, which was even more prominent under warming. In this situation, the plastidial reductants fueled the mitochondrial electron transport chain directly, which in turn resulted in a redox-mediated downregulation of the respiratory CO2 release, which consequently maximized net biomass retention of the whole cell.
Finally, Publication III and IV aimed to understand how temperature affects phytoplankton physiology on the level of natural Arctic phytoplankton communities. To this end, communities from the open-ocean Fram Strait (Publication III) and a coastal fjord system in Svalbard (Publication IV) were incubated under similar temperature and light conditions as in Publication II. Biomass accumulation, O2 fluxes of photosynthesis and respiration, photophysiology as well as community composition were assessed using a ship-going MIMS system or O2 optodes, FRRf as well as rRNA 18s metabarcoding, respectively. Both communities exhibited a stimulated net biomass retention under warming scenarios, despite a lowered net O2 production, due to strongly increasing respiratory O2 consumption. These responses were not accompanied by distinct species shifts, e.g. towards more heterotrophic communities, indicating that the opposing temperature responses of O2- and C-fluxes in the communities were likely a result of the same physiological regulatory mechanisms as observed in the single-strain experiment.
Findings from single-strain as well as community experiments strongly indicate that a metabolic coupling of chloroplasts and mitochondria is a fundamental mechanism across communities to plastically respond to ocean warming, that allows Arctic phytoplankton to thrive under increasing temperatures. In line with this, all Publications also revealed that optimal temperatures for growth and biomass production exceeded those in the present Arctic Ocean, suggesting a stimulation of biomass accumulation at least under moderate warming. Data of photophysiological assessments further signify synergistic beneficial effects on photosynthetic processes under a combined increase of temperature and light intensity, as it is projected for the future Arctic Ocean
Tourism, gender, and climate change adaptation in Kenya's coast
No full textTourism’s development along Kenya’s coast has undergone gradual yet significant transformation shaped by political dynamics, foreign investment, and local culture. Originating from colonial leisure pursuit in the early 1900s, Kenya’s coastal tourism evolved into a key pillar in both national and devolved government plans. In recent years, the national government has taken a more active role in guiding tourism’s trajectory, building on a legacy established by foreign investors who set up the region’s early resort economy. These developments have had substantial impact on the livelihoods of coastal communities, influencing opportunities, for example employment opportunities for women who make up the majority of global tourism workforce. The developments also expose local communities to new vulnerabilities, particularly considering gendered risks in ocean governance and climate change.
As climate change intensifies threats to marine life, coastal settlements, and tourism infrastructure, every decision made about tourism development becomes even more significant. The sector’s future depends not only on healthy marine environments, but also on resilience of local communities involved in tourism work. In this context, the central argument of this study is that adaptation with relevance to Kenya’s coastal tourism is both relational and political, shaped by imbalances in power relations and competing sectoral priorities in the ocean economy. Framed through the lens of feminist political ecology, this study examines how power asymmetries influence climate adaptation in coastal tourism, taking note of incorporation or neglect of gender responsiveness within the process.
Despite tourism’s consistent ranking among Kenya’s top contributors to Gross Domestic Product and ocean economy, the sector has in the past failed to establish strong local community linkages. As a result, many coastal communities remain excluded from the sector’s meaningful economic engagement and decision making. This exclusion becomes more visible as climate change impacts intensify, with the effects of tourism’s vulnerabilities spilling over to communities that depend on the sector. A key challenge is that these communities are rarely central in adaptation planning, illustrating political hierarchies that feminist political ecology critiques, where local agency and gendered vulnerabilities are obscured. As this pattern eventually erases local and place based knowledge, it reflects tensions within development narratives shown to marginalize alternative ways of knowing.
This study is structured around three main objectives. First, a literature review investigates how gender is approached in tourism research on climate change, revealing persistence of disciplinary silos between sub fields. Second, through participatory photo voicing workshops with women in a coastal tourism destination, the research showcases how local coastal communities experience climate change impacts, detailing their descriptions of non-economic loses. This participatory approach ensures that women’s voices are foregrounded, especially considering literature evidence of sidelining of women’s voices on environmental matters. Third, the study uses mental modeling to compare how different stakeholder groups conceptualize climate risks to coastal tourism. The findings note striking differences between policy makers and tourism practitioners, with the latter, shown by literature and policy review, to be often excluded from formal decision making. Top-down processes and tokenistic participation, undermine effective, inclusive adaptation, as they reinforce existing hierarchies and overlook grassroots knowledge. Collectively, findings from this study contribute to debates on climate justice and the need to re-center local voices, particularly those of women, in shaping equitable and sustainable future for coastal tourism and ocean economy
Skill Acquisition and Player Performance in Video Games and Esports
No full textVideo games have become one of the most popular entertainment products in the world during the past decade. Backed by a profitable industry, video games entice millions of players to play for hundreds and sometimes thousands of hours. Many of these players seek to acquire the necessary skills to excel in their favourite games, be it as a personal challenge in the context of single player games or to participate in structured competition for competitive multiplayer games also known as esports. However, casual players and professionals alike show a distinct lack of any systematic approaches to training in the context of their games and resort to brute forcing adaption through playing for as many hours as possible every day. This behavioural pattern involves sitting and intense computer use for extended periods of time which can lead to adverse mental and physical health consequences such as disturbed sleep patterns, overuse injuries in the hands and wrists, and back pain. To address this problem, this dissertation compiles necessary knowledge about the multifaceted nature of skill and skill acquisition while distinguishing between perceptual learning, response selection, attentional skill, motor skill, and cognitive skill as distinct dimensions that require different training methods. This knowledge functions as a theoretical foundation for structured training in video games. To apply this knowledge, this dissertation introduces the Player Challenge Model, which provides a step by step framework for the analysis of video games for the sake of extracting skill requirements based on the mechanics a game employs to facilitate the selection of suitable training methods. Two user studies on the effects of long play sessions of League of Legends conducted in this thesis emphasize the importance of using such a framework as both studies show detrimental effects on performance and win rates with indications for mental fatigue, which in turn negatively impacts cognitive functions associated with learning. Alternative methods for video game training are explored as part of the Player Challenge Model and put to the test in two additional user studies, one focused on distributed training in an ecologically valid esports task and the other exploring the use of a fully integrated digital tool comparing immediate and delayed feedback in a speedrunning task. The results demonstrate the potential of exploring new training approaches for video games as well as the associated difficulties. Together with extensive literature work and expert interviews conducted with professional fighting game players that confirm the lack of systematic training approaches even in those players who succeed in their chosen games, this thesis provides the necessary ground work for further development of structured training systems in video games and emphasize the potential utility of their use
Datenschutzkonzept zur Nutzung von georeferenzierten Daten am Gastwissenschaftsarbeitsplatz des FDZ-FGZ
No full textIm Folgenden beschreiben wir ein Datenschutzkonzept für einen Gastwissenschaftsarbeitsplatz, der es Forschenden erlaubt, kleinräumige Regionalindikatoren und georeferenzierte Daten an Surveydaten des FGZ anzuspielen und gemeinsam auszuwerten. Das Konzept beinhaltet eine technische Umsetzung, die eine strikte Trennung der anonymisierten Surveydaten von den Geokoordinaten der Befragtenhaushalte sicherstellt. Zum besseren Verständnis erläutern wir im ersten Teil zunächst die wissenschaftlichen und institutionellen Hintergründe des Vorhabens
Implementation of climate education in geography curricula - An analysis of the geography curriculum process and the actors involved
No full textDie Dissertation „Implementierung der Klimabildung in die Geographielehrpläne - Eine Untersuchung des geographischen Lehrplanprozesses und der beteiligten Akteure“ zeigt auf, welche Regulierungen und Praktiken die Implementierung der Klimabildung in die deutschen Geographielehrpläne beeinflussen.
Der geographische Lehrplanprozess sowie die beteiligten Akteure mit ihren unterschiedlichen Positionen und Interessen werden mithilfe einer Literaturrecherche und zehn qualitativen Experteninterviews dargelegt. Schließlich wird herausgearbeitet, von welchen Akteuren die Entscheidungen zur Implementierung eines Themas im geographischen Lehrplanprozess letztlich getroffen werden. Da in den bereits verabschiedeten Lehrplänen die endgültigen Entscheidungen zu den implementierten Inhalten stehen, soll durch eine inhaltlich strukturierende qualitative Inhaltsanalyse aufgezeigt werden, in welchen Geographielehrplänen der Klimawandel bereits implementiert ist. Mit einer Vollerhebung sind insgesamt 115 Geographielehrpläne der Sekundarstufe I und II an Gymnasien (Klassenstufen 5 bis 12 bzw. 13 je nach Bundesland), die von 1990 bis 2020 in den 16 Bundesländern erschienen sind, hinsichtlich der inhaltlichen Vorgaben zum globalen Klimawandel untersucht worden.
Aus den Experteninterviews und der Inhaltsanalyse der Geographielehrpläne wird deutlich, dass die Implementierung und Zusammenstellung von Lehrplaninhalten von sehr vielen bestehenden sowie neuen Regulierungen und Praktiken abhängt. Zentrales Ergebnis ist, dass in den Geographielehrplänen eine stetige und umfangreiche Zunahme der Klimabildung stattfindet, sodass bis zum Ende des Untersuchungszeitraums 15 Bundesländer die Klimabildung ganzheitlich in den Geographielehrplänen eingeführt haben
Kohlenstoffzyklus in (sub-) antarktischen marinen anoxischen Sedimenten
No full textIm marinen Sediment stellt die anaerobe Zersetzung organischen Kohlenstoffs durch eine
mikrobielle Gemeinschaft einen wichtigen Teil des globalen Kohlenstoffzyklus dar. Die
Folgen der globalen Erwärmung sind in den marinen Sedimenten der polaren Regionen bereits
jetzt deutlich wahrnehmbar. Die Temperatur steigt und beschleunigtes Abschmelzen der
Gletscher führt durch Gletscherschmelzwasser zu einem erhöhten Eintrag von Nährstoffen wie
Metalloxiden in die Sedimente. Da diese Metalloxide als terminale Elektronenakzeptoren für
anaeroben organischen Kohlenstoffabbau dienen können, wird ein Einfluss der beschriebenen
Änderungen auf jene Prozesse und die assoziierten Mikroorganismen vorausgesagt.
Änderungen können allerdings nur sinnvoll vorausgesagt werden, wenn der aktuelle Status des
untersuchten Systems verstanden wurde und insbesondere marine Sedimente in der Antarktis
sind bisher kaum untersucht worden.
Die Sedimente der in dieser Dissertation untersuchten Gebiete, Potter Cove auf der König-
Georg-Insel/Isla 25 de Mayo an der Westantarktischen Halbinsel und Südgeorgien im
Südatlantik, werden stark durch schmelzende Gletscher beeinflusst. Ich habe die mikrobielle
Gemeinschaft und Geochemie in situ untersucht, fokussiert auf den finalen Kohlenstoffabbau.
Zusätzlich habe ich in simplen Inkubationsexperimenten und Inkubationen mit stabiler
Isotopenbeprobung (stable isotope probing: SIP) auf RNA-Level die acetatabbauenden
Mikroorganismen untersucht und Eisenoxide, Manganoxide und Sulfat als terminale
Elektronenakzeptoren getestet. Eisenoxide und, wenn zugesetzt, auch Manganoxide, dienten
als Elektronenakzeptoren für die Acetatoxidierung. Der hauptsächlich verantwortliche
Mikroorganismus für die Eisenreduktion in allen untersuchten Sedimenten war der
unkultivierte Sva1033 (Desulfuromonadales). Dies ist der erste experimentelle Nachweis für
eine Stoffwechselfähigkeit dieser kaum untersuchten Gruppe. Da Sva1033 der dominante
eisenreduzierende Mikroorganismus in situ und in RNA-SIP Inkubationen, sogar bei höheren
Temperaturen, war, konnte ich ihn als Schlüsselart für Acetatoxidation in den untersuchten
Umgebungen identifizieren.
Des Weiteren konnte durch acetatabbauende SIP Experimente eine mikrobielle Gemeinschaft
gezeigt werden, die über einen weiten Temperaturgradienten aktiv war, zum Beispiel die
Mikroorganismen Sva1033 und Desulfuromonas. Andere Mikroorganismen waren nur bei
bestimmten Temperaturen aktiv, zum Beispiel Arcobacteraceae bei niedrigen und
Desulfuromusa bei hohen Temperaturen. Desulfuromusa war zusätzlich der dominierende Mikroorganismus, der bei niedriger in situ Temperatur Manganoxide reduziert und Acetat
oxidiert hat.
Trotz ihrer hohen Abundanz in den in situ Sedimenten, schienen sulfatreduzierende
Mikroorganismen in all den durchgeführten Experimenten nicht zur Acetatoxidation
beizutragen, waren allerdings in mehreren SIP Experimenten im Hintergrund vorhanden. Des
Weiteren konnten SIP Experimente keinen autotrophischen Lebensstil der Sulfatreduzierer
zeigen, obwohl Sulfatreduktion durch Acetat- und Wasserstoffzugabe stimuliert werden
konnte. Auch die durch Sulfatreduzierer verwendeten Elektronendonoren bleiben schwer zu
fassen und weitere Untersuchungen sind notwendig. Stattdessen wurde ein potentiell neuer
Bakterienstamm von Sulfurimonas in SIP Experimenten mit den höchsten
Sulfatreduktionsraten identifiziert, welcher einen anaeroben, psychrophilen Lebensstil
vollführt und Acetat und CO2 assimiliert hat. Ich schlage Sulfid als genutzten Elektronendonor
und Syntrophie mit einem anderen Mikroorganismus als elektronenakzeptierenden Partner vor,
allerdings werden weitere Experimente benötigt um diese Hypothesen zu bestätigen und
weiteres Licht auf den durch den Mikroorganismus durchgeführten Metabolismus zu werfen.
Durch Beschreibungen und vorausgesagte Stoffwechselaktivitäten der mikrobiellen
Gemeinschaft in gletscherbeeinflussten, marinen Sedimenten der Antarktis tragen die
Untersuchungsergebnisse dieser Dissertation zum Forschungsfeld der anaeroben
Mikroorganismen in marinen Sedimenten bei. Aufgrund meiner Forschungsergebnisse halte
ich es für wahrscheinlich, dass die organische Materialien zersetzende mikrobielle
Gemeinschaft stark durch vom Gletscherschmelzwasser eingetragene Nährstoffe beeinflusst
wird und dadurch höchst sensibel auf zukünftige Änderungen in dieser durch globale
Erwärmung beeinflussten Umwelt reagieren könnte
From Heatwaves to Cold Spells: How Extreme Temperature Events Shape Inflation in Germany
No full textIn this paper, we develop a novel methodology to identify temperature surprise shocks for hot and cold extreme weather events using granular ground station- and satellite-based weather data for Germany. We focus on food and energy prices, which are key drivers of inflation in Germany and, at the same time, are themselves strongly affected by climate-related shocks. A positive heat shock of one standard deviation increases food prices by up to 0.39% in summer, while the same type of shock in winter decreases energy prices by 0.88%. Moreover, our results indicate that food prices are driven primarily by supply-side factors, as the interaction of a heat shock with a drought variable amplifies the effect through its impact on agricultural production, whereas energy prices respond mainly to demand-side factors, such as changes in heating and cooling needs. Using our identified weather shocks, we estimate the causal effects of extreme temperatures on these two components and trace their pass-through to headline inflation. These results are robust when accounting for nonlinearities arising from seasonality and shock magnitude, the role of transmission channels such as renewable energy production, droughts, and different learning periods in which agents form expectations from past weather shocks.250
Ästhetik der Negation, Semiotik der Subversion: Adorno und Kristeva im Dialog der Differenz
No full textDer Beitrag untersucht die kritische Funktion ästhetischer Erfahrung im Spannungsfeld zwischen Theodor W. Adornos negativer Dialektik und Julia Kristevas Theorie des Abjekten. Ausgehend von der Frage nach dem Potenzial künstlerischer Praxis zur Subjektkritik wird gezeigt, dass Kunst nicht als affirmatives Medium gesellschaftlicher Ordnung fungiert, sondern als Ort ihrer Subversion. Während Adorno in der autonomen Form des Kunstwerks ein Widerstandspotenzial gegen die Totalität des Bestehenden erkennt, eröffnet Kristeva durch die Kategorie der Abjektion einen Zugang zur prä-subjektiven Erfahrung und zur Destabilisierung symbolischer Ordnung. Beiden Ansätzen gemeinsam ist die Einsicht, dass ästhetische Erfahrung weniger in der Mitteilung von Sinn als in der Erschütterung von Identität besteht. Die Arbeit entwickelt diese theoretische Konstellation anhand exemplarischer Werkanalysen (Celan, Plath) und zeigt, wie Kunst als Zone des Risses erscheint – als Möglichkeitsraum eines kritischen Subjekts, das sich in der Auseinandersetzung mit dem Nicht-Identischen, dem Triebhaften und dem Verstörenden konstituiert