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  • 1
    Publication Date: 2023-11-16
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Recent decades have witnessed a sharp biodiversity decline in freshwaters due to multiple stressors. The presence of multiple stressors is expected to affect community structure and interactions in freshwater ecosystems, with subsequent functional consequences. We synthesized the state of experimental, manipulative multiple‐stressor studies that focused on multispecies assemblages in freshwaters. Compared to rivers and lakes, wetland and groundwater ecosystems have received much less attention in identified multiple‐stressor research. Most of the identified studies investigated combinations of abiotic stressors (e.g., nutrients, pesticides, heavy metals, warming, altered flow and sedimentation) on microbes and invertebrates while biotic stressors and vertebrates have been largely overlooked. The responses of community structure (e.g., alpha diversity, biomass, and abundance), some community/ecosystem functions (e.g., photosynthesis and autotrophic activity, leaf litter degradation), and morphological traits like body size and growth forms were frequently investigated. We observed a clear gap in biotic interactions under multiple‐stressor conditions, which, although difficult to study, could impede a deeper mechanistic understanding of how multiple stressors affect freshwater assemblages and associated ecological processes. Although information on ecosystem recovery pathways following restoration is critical for freshwater management, few studies were designed to provide such information, signifying the disconnections between multiple‐stressor research and environmental practice. To bridge these gaps, researchers and environmental practitioners need to work together to identify key stressors and interactions at different spatial and temporal scales and prioritize stressor management. Such collaborations will enhance the translation of multiple‐stressor research into efficient management strategies to protect and restore freshwater ecosystems.〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Deutscher Akademischer Austauschdienst http://dx.doi.org/10.13039/501100001655
    Description: Leibniz‐Gemeinschaft
    Description: German Federal Ministry of Education and Research (BMBF)
    Keywords: ddc:333.95 ; biodiversity ; freshwater ; management ; multiple stressors ; systematic literature review
    Language: English
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  • 2
    Publication Date: 2023-12-12
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Global warming, bioinvasions, and parasitism affect single‐species performances and species interactions, substantially impacting the structure and stability of marine ecosystems. In light of accelerated global change, the information derived from studies focusing on single species and single drivers is insufficient, calling for a multi‐stressor approach under near‐natural conditions. We investigated the effects of warming (+3°C) on the performance of a benthic community composed of native and invasive macroalgae, consumers and a trematode parasite in a mesocosm setting. We also assessed the effects of warming and parasitism on the survival and growth of gastropods and mussels and the thermal dependency of trematode performance. Our findings show that warming and grazing by infected gastropods had a large detrimental effect on the invasive macroalga growth. Furthermore, the single and interactive effects of parasitism and warming were detrimental to intermediate host survival and growth, especially to large mussels. Finally, cercarial emergence positively correlated to the natural peaks of summer temperatures, while infection intensity in mussels was higher in larger individuals. Our findings suggest that grazing and warming will be detrimental to the invasive macroalga, favoring the native alga. Moreover, parasitism will enhance grazing, especially in summer, when higher temperatures trigger parasite development. However, parasite‐enhanced grazing may be buffered by higher mortality or a shift in the size of infected intermediate hosts under warming. Our findings demonstrate how complex effects of ocean warming can be on food webs and how they can be mediated by parasitism and, as a result, influence native and invasive macroalgae differently.〈/p〉
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Keywords: ddc:577.7 ; Baltic community ; climate change ; bioinvasions ; parasitism ; interactive effects ; macroalgae growth
    Language: English
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  • 3
    Publication Date: 2023-12-14
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Atlantic herring (〈italic toggle="no"〉Clupea harengus〈/italic〉) plays a key role within temperate marine food webs and is targeted by a significant over‐regional fishery. Due to its high economic importance, dynamics in herring stock biomass and recruitment are closely monitored, forming the basis for fisheries management advice. As recruitment patterns translate into the adult stock biomass, early life stage ecology has been thoroughly addressed in fisheries research. Larval monitoring programs commonly focus on length measurements and abundance indices, rarely, information on larval developmental stages is given. As length is highly influenced by temperature, salinity and food availability, their size range can significantly vary between cohorts, populations, and ecotypes. Nowadays, a systematic staging system from the 1970s provides the standard guide for herring larval development, although it does not fully resolve important developmental stages. Here, we propose an improved staging system based on external morphology and skeletal development of herring larvae. The staging system has been developed and tested with herring larvae from different populations of the North and Baltic Sea to ensure applicability. The system comprises 15 stages (+substages) in 5 major developmental phases: the yolk sac phase, the dorsal fin development, the caudal fin development, the pelvic fin development, and the juvenile phase. This staging system aims to simplify herring larval staging to gain a more specific picture of early life dynamics. Because of the detailed description of the development, future studies are better equipped to identify stages which, for example, show high mortality rates and better link them to environmental circumstances.〈/p〉
    Description: Universität Rostock http://dx.doi.org/10.13039/501100012688
    Description: Promotionsstipendium Universität Rostock
    Keywords: ddc:597 ; Atlantic herring ; larval phases ; staging system
    Language: English
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  • 4
    Publication Date: 2023-12-19
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉We monitored stable water isotopes in liquid precipitation and atmospheric water vapour (δ〈sub〉v〈/sub〉) using in situ cavity ring‐down spectroscopy (CRDS) over a 2 month period in an urban green space area in Berlin, Germany. Our aim was to better understand the origins of atmospheric moisture and its link to water partitioning under contrasting urban vegetation. δ〈sub〉v〈/sub〉 was monitored at multiple heights (0.15, 2 and 10 m) in grassland and forest plots. The isotopic composition of δ〈sub〉v〈/sub〉 above both land uses was highly dynamic and positively correlated with that of rainfall indicating the changing sources of atmospheric moisture. Further, the isotopic composition of δ〈sub〉v〈/sub〉 was similar across most heights of the 10 m profiles and between the two plots indicating high aerodynamic mixing. Only at the surface at ~0.15 m height above the grassland δ〈sub〉v〈/sub〉 showed significant differences, with more enrichment in heavy isotopes indicative of evaporative fractionation especially after rainfall events. Further, disequilibrium between δ〈sub〉v〈/sub〉 and precipitation composition was evident during and right after rainfall events with more positive values (i.e., values of vapour higher than precipitation) in summer and negative values in winter, which probably results from higher evapotranspiration and more convective precipitation events in summer. Our work showed that it is technically feasible to produce continuous, longer‐term data on δ〈sub〉v〈/sub〉 isotope composition in urban areas from in situ monitoring using CRDS, providing new insights into water cycling and partitioning across the critical zone of an urban green space in Central Europe. Such data have the potential to better constrain the isotopic interface between the atmosphere and the land surface and to thus, improve ecohydrological models that can resolve evapotranspiration fluxes.〈/p〉
    Description: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉In situ measurements of urban atmospheric water isotopes (δ〈sub〉v〈/sub〉) at different heights produce reliable and stable high‐resolution data. Urban atmospheric vapour is influenced by varying drivers depending on the type of green space. δ〈sub〉v〈/sub〉 above grassland and tree stands was similar at 10 m height, but near‐surface δ〈sub〉v〈/sub〉 indicated higher evaporation and vapour enrichment over grass. We detected occasional dis‐equilibrium between vapour and precipitation isotopes.〈boxed-text position="anchor" content-type="graphic" id="hyp14989-blkfxd-0001" xml:lang="en"〉 〈graphic position="anchor" id="jats-graphic-1" xlink:href="urn:x-wiley:08856087:media:hyp14989:hyp14989-toc-0001"〉 〈/graphic〉 〈/boxed-text〉〈/p〉
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Einstein Stiftung Berlin http://dx.doi.org/10.13039/501100006188
    Description: Leverhulme Trust http://dx.doi.org/10.13039/501100000275
    Description: German Research Foundation http://dx.doi.org/10.13039/501100001659
    Description: Einstein Research Unit
    Description: Einstein Foundation Berlin and Berlin University Alliance
    Description: BiNatur
    Description: BMBF http://dx.doi.org/10.13039/501100002347
    Description: Leverhulme Trust through the ISO‐LAND project
    Keywords: ddc:551.6 ; atmospheric vapour isotopes ; cities ; ecohydrology ; equilibrium assumption ; in situ monitoring ; urban green spaces
    Language: English
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  • 5
    Publication Date: 2023-07-21
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The countless kettle holes in the Late Pleistocene landscapes of Northern Europe are hotspots for biodiversity and biogeochemical processes. As a rule, they are hydraulically connected to the shallow groundwater system. The rapid, intensive turnover of carbon, nutrients and pollutants in the kettle holes therefore has a major impact on the quality of the shallow groundwater downstream. As a result of high‐evapotranspiration rates from their riparian vegetation or strong storm events, the process of downstream groundwater flow may stagnate and reverse back towards the kettle hole, making interactions between the groundwater and kettle hole more complex. Furthermore, the highly heterogeneous soil landscape in the catchment contributes to this complexity. Therefore, the present study aims to enhance our understanding of this complicated interaction. To this end, 24 model variants were integrated into HydroGeoSphere, capturing a wide range of uncertainties in quantifying the extent and timing of groundwater flow reversal between a kettle hole and the adjacent aquifer. The findings revealed that the groundwater flow reversal lasted between 1 month and 19 years at most and occurred in a distance of more than 140 m downstream of the kettle hole. Our results demonstrated that the groundwater flow reversal arises especially often in areas where the shallow aquifer possesses low‐hydraulic conductivity. There may also be a recurrent circulating flow between the groundwater and kettle hole, resulting in solute turnover within the kettle hole. This holds particularly true in dry periods with medium to low‐water levels within the kettle hole and a negative water balance. However, shallow groundwater flow reversals are not necessarily a consequence of seasonal effects. In this respect, the properties of the local shallow aquifer by far outweigh the effect of the kettle hole location in the regional flow regime.〈/p〉
    Description: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Frequency of the direction of water flow from a kettle hole towards the aquifer and its reversal for different aquifer sediments on a vertically cross section through the water body and the surrounding aquifer.〈boxed-text position="anchor" content-type="graphic" id="hyp14890-blkfxd-0001" xml:lang="en"〉 〈graphic position="anchor" id="jats-graphic-1" xlink:href="urn:x-wiley:08856087:media:hyp14890:hyp14890-toc-0001"〉
    Description: https://open-research-data.zalf.de/default.aspx
    Keywords: ddc:551.49 ; groundwater flow reversal ; HydroGeoSphere ; kettle hole ; numerical experiment ; surface–groundwater interaction
    Language: English
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  • 6
    Publication Date: 2023-07-21
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Freshwater biodiversity, from fish to frogs and microbes to macrophytes, provides a vast array of services to people. Mounting concerns focus on the accelerating pace of biodiversity loss and declining ecological function within freshwater ecosystems that continue to threaten these natural benefits. Here, we catalog nine fundamental ecosystem services that the biotic components of indigenous freshwater biodiversity provide to people, organized into three categories: material (food; health and genetic resources; material goods), non‐material (culture; education and science; recreation), and regulating (catchment integrity; climate regulation; water purification and nutrient cycling). If freshwater biodiversity is protected, conserved, and restored in an integrated manner, as well as more broadly appreciated by humanity, it will continue to contribute to human well‐being and our sustainable future via this wide range of services and associated nature‐based solutions to our sustainable future.〈/p〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉
    Description: María de Maeztu excellence accreditation 2018‐2022
    Description: Ministerio de Ciencia e Innovación (MCIN) http://dx.doi.org/10.13039/501100004837
    Description: Leibniz Competition: Freshwater Megafauna Futures
    Description: CGIAR Initiative on NEXUS Gains
    Keywords: ddc:333.9 ; ecosystem services ; freshwater biodiversity ; freshwater ecosystems ; freshwater life
    Language: English
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  • 7
    Publication Date: 2023-07-19
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The genesis of floods in large river basins often is complex. Streamflow originating from precipitation and snowmelt and different tributaries can superimpose and cause high water levels, threatening cities and communities along the riverbanks. For better understanding the mechanisms (origin and composition) of flood events in large and complex basins, we capture and share the story behind major historic and projected streamflow peaks in the Rhine River basin. Our analysis is based on hydrological simulations with the mesoscale Hydrological Model forced with both meteorological observations and an ensemble of climate projections. The spatio‐temporal analysis of the flood events includes the assessment and mapping of antecedent liquid precipitation, snow cover changes, generated and routed runoff, areal extents of events, and the above‐average runoff from major sub‐basins up to 10 days before a streamflow peak. We introduce and assess the analytical setup by presenting the flood genesis of the two well‐known Rhine floods that occurred in January 1995 and May 1999. We share our extensive collection of event‐based Rhine River flood genesis, which can be used in‐ and outside the scientific community to explore the complexity and diversity of historic and projected flood genesis in the Rhine basin. An interactive web‐based viewer provides easy access to all major historic and projected streamflow peaks at four locations along the Rhine. The comparison of peak flow genesis depending on different warming levels elucidates the role of changes in snow cover and precipitation characteristics in the (pre‐)Alps for flood hazards along the entire channel of the Rhine. Furthermore, our results suggest a positive correlation between flood magnitudes and areal extents of an event. Further hydro‐climatological research is required to improve the understanding of the climatic impact on the Rhine and beyond.〈/p〉
    Description: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The genesis of riverine floods in large river basins often is complex. Streamflow originating from precipitation and snowmelt and different tributaries can superimpose and cause high water levels threatening cities and communities along the riverbanks. In this study, we capture and share the story behind major historic and projected streamflow peaks in the large and complex basin of the Rhine River.〈boxed-text position="anchor" content-type="graphic" id="hyp14918-blkfxd-0001" xml:lang="en"〉 〈graphic position="anchor" id="jats-graphic-1" xlink:href="urn:x-wiley:08856087:media:hyp14918:hyp14918-toc-0001"〉
    Description: https://doi.org/10.5281/zenodo.3239055
    Description: https://github.com/ERottler/rhine-flood-genesis
    Description: http://natriskchange.ad.umwelt.uni-potsdam.de:3838/rhine-flood-genesis
    Description: https://b2share.eudat.eu/records/72d7a4f5d38043d1a137228b39c7ecc3
    Keywords: ddc:551.46 ; climate change ; flood composition ; flood genesis ; mHM ; model simulations ; quantile extent ; Rhine River ; spatio‐temporal analysis ; web‐based dashboard
    Language: English
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  • 8
    Publication Date: 2023-11-17
    Description: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Detrital single‐grain zircon U–Pb geochronology is a powerful tool for provenance studies if information on the source rocks is available. This paper proposes a new source‐rock classification tool that uses the degree of annealing of radiation damage in detrital zircon; the annealing is expressed by the relationship between the width (full‐width at half‐maximum; FWHM) of the 〈italic toggle="no"〉v〈/italic〉〈sub〉3〈/sub〉[SiO〈sub〉4〈/sub〉] Raman band at ~1008 cm〈sup〉−1〈/sup〉 and the calculated α‐dose. The host rocks of the zircons are classified into three types according to their emplacement process and/or thermal history: volcanic and rapidly cooled plutonic and high‐grade metamorphic rocks (type 1); rocks with hydrothermal zircons (type 2); slowly cooled igneous and metamorphic rocks (type 3). We construct a naive Bayes prediction model by training it with a collection of zircons of known types. The unknown zircons are assigned a probability of derivation from a specific host‐rock type. This classification scheme is best used as an accessory tool in provenance studies that apply detrital zircon U–Pb geochronology.〈/p〉
    Description: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Zircons are classified into three types based on annealing state revealed by Raman analysis and calculated α‐dose. This classification can be used to distinguish zircon in provenance study.〈boxed-text position="anchor" content-type="graphic" id="gj4751-blkfxd-0001" xml:lang="en"〉 〈graphic position="anchor" id="jats-graphic-1" xlink:href="urn:x-wiley:00721050:media:gj4751:gj4751-toc-0001"〉 〈/graphic〉 〈/boxed-text〉〈/p〉
    Description: Natural Science Foundation of Hubei Province http://dx.doi.org/10.13039/501100003819
    Description: National Natural Science Foundation of China http://dx.doi.org/10.13039/501100001809
    Keywords: ddc:549 ; annealing ; Bayesian probability ; provenance analysis ; radiation damage ; zircon classification
    Language: English
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  • 9
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    John Wiley & Sons, Inc. | Hoboken, USA
    Publication Date: 2024-01-24
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The IPCC's Sixth Assessment Report warns in stark terms that many long inhabited parts of the world are now on course to become uninhabitable. As astronomers continue to search the universe for new habitable planets, it is equally essential to historicize the consequences of changing habitability on this one. This article reviews how scholars have engaged with the widely noted but rarely theorized categories of “habitability” and “uninhabitability.” While tracing longer imperial genealogies, the primary focus is on notions of habitability in relation to European global empires in the nineteenth and twentieth centuries, and their postcolonial legacies. The article traces three key themes in the literature: that habitability was inherently limited, and beyond those limits allegedly lay uninhabitability; that habitability was differential and that certain places were habitable for some groups but not others (but that this might be changed by technological interventions); and finally, that the limits of habitability were not static, but could change for both better and worse. Here the links between colonialism and ideas of acclimatization, terraforming, “improvement,” deliberate uninhabitability, and an “Anthropocene” have all been central to the literature. These have often been closely associated with insidious forms of environmental determinism, which are taking on new forms in an age of crisis (especially in narratives around climate and migration). By drawing together previously disparate literatures, this article ultimately calls on scholars to embrace habitability studies more widely, and to expand on their interdisciplinary potential for communicating the societal consequences of a changing climate.〈/p〉
    Description: European Commission http://dx.doi.org/10.13039/501100000780
    Description: Irish Research Council http://dx.doi.org/10.13039/501100002081
    Keywords: ddc:910 ; Anthropocene ; climate change ; empire ; environmental determinism ; habitability
    Language: English
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  • 10
    Publication Date: 2024-01-24
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉In order not to significantly overshoot maximum levels of warming like the 1.5 and 2°C target we must stay within a fixed emissions budget. How to fairly distribute the entitlements to emit within such a budget is perhaps the most intensely discussed question in all of climate justice. In our review we discuss the most prominent proposals in moral and political philosophy on how to solve this question and put a special emphasis on scholarly contributions from the last decade. We canvass the arguments for and against emissions egalitarianism, emissions sufficientarianism, and emissions grandfathering as well as the debates surrounding them. These are how to deal with non‐compliance, how to split emissions between producers and consumers, how to best account for terrestrial carbon sinks, and whether emissions from having children should be subtracted from parents' emissions budgets. From the viewpoint of justice, it matters not only that we act against climate change but also how we do so. This review aims to elucidate one of the major ways in which our reaction to climate change could be just or unjust.〈/p〉
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Keywords: ddc:363.7 ; carbon sinks ; emissions egalitarianism ; historical responsibility ; integrationism ; non‐compliance
    Language: English
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  • 11
    Publication Date: 2024-03-25
    Description: Mass developments of toxic cyanobacteria have increased in frequency due to global warming and eutrophication. Such cyanobacterial blooms impact whole freshwater ecosystems, especially reducing the abundance of herbivory species of the genus Daphnia. These negative effects on Daphnia have frequently been attributed to cyanobacterial secondary metabolites, among them hepatotoxic microcystins and protease inhibitors. Protease inhibitors inhibit major digestive proteases in the gut of Daphnia which results in reduced fitness, that is, population growth. To date evidence for local adaptation of Daphnia to cyanobacteria is confined to microcystin‐producing cyanobacteria and based on comparison of individual clones from different populations but lacks evidence from multiclone microcosm experiments. In the present study, D. magna clones from a Swedish lake where they coexist with the microcystin‐free Microcystis sp. strain BM25 were compared to clones from a Polish population without cyanobacteria, first in single‐clone experiments and subsequently in a multiclonal experimental population. The Swedish clones were assumed to be locally adapted to this protease inhibitor‐producing cyanobacterium and indeed showed higher population growth rates, a proxy for fitness, and dominated the population in the presence of dietary Microcystis sp. BM25, but not in the absence of this cyanobacterium. The results indicate an adaptive tolerance of the Swedish population and point at local adaptation to locally co‐occurring protease inhibitor‐producing cyanobacteria.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:577.7 ; Daphnia magna ; multiclonal study ; toxic cyanobacteria ; adaption ; experiments
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  • 12
    Publication Date: 2024-03-12
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Iron (Fe) and manganese (Mn) availability and the divergent requirements of phytoplankton species were recently shown to be potential important drivers of Southern Ocean community composition. Knowledge about Antarctic phytoplankton species requirements for Fe and Mn remains, however, scarce. By performing laboratory experiments and additional calculations of the photosynthetic electron transport, we investigated the response of the ecologically important species 〈italic toggle="no"〉Phaeocystis antarctica〈/italic〉 under a combination of different Fe and Mn concentrations. Fe deprivation alone provoked typical physiological characteristics of Fe limitation in 〈italic toggle="no"〉P. antarctica〈/italic〉 (e.g., lowered growth and photosynthetic efficiency). In comparison, under Mn deprivation alone, the growth and carbon production of 〈italic toggle="no"〉P. antarctica〈/italic〉 were not impacted. Its tolerance to cope with low Mn concentrations resulted from an efficient photoacclimation strategy, including a higher number of active photosystems II through which fewer electrons were transported. This strategy allowed us to maintain similar high growth and carbon production rates as FeMn‐enriched cells. Due to its low Mn requirement, 〈italic toggle="no"〉P. antarctica〈/italic〉 performed physiologically as Fe‐deprived cells under the combined depletion of Fe and Mn. Hence, our study reveals that different from other Southern Ocean phytoplankton species, 〈italic toggle="no"〉P. antarctica〈/italic〉 possesses a high capacity to cope with natural low Mn concentrations, which can facilitate its dominance over others, potentially explaining its ecological success across the Southern Ocean.〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.1594/PANGAEA.944462
    Keywords: ddc:577.7 ; Southern Ocean ; Antarctic phytoplankton ; Trace metal ; photophysiology ; carbon fixation
    Language: English
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  • 13
    Publication Date: 2024-02-14
    Description: The United Nations Food and Agricultural Organization (FAO) approved the Hargreaves‐Samani formula (HAR‐85) as an alternative to the standard Penman‐Monteith method (FAO‐PM) for estimating grass reference evapotranspiration (ETo). With much less data demand, HAR‐85 is unequivocally useful where meteorological variables are often scarce, incomplete or unavailable. Herein, we evaluate HAR‐85 against FAO‐PM across 2.505 million km2, representing Sudan and South Sudan and encompassing wide hydroclimate domains including the Nile River. We further propose simple year‐round and seasonal adjustment models to correcting HAR‐85 across the entire study area. The models express HAR‐85's error in multiple linear regressions in terms of latitude, longitude, altitude and/or monthly rainfall. Varying data periods, including odd, even and all years, are used in the evaluation and the adjustment models development and validation processes to investigate the influence of changing data period. A suit of eight performance indicators shows dependency of the original bias of HAR‐85 on the geographical location, monthly rainfall amount, season of the year and data period. All error indicators amplify southward from the hyper‐arid region to the dry sub‐humid zone. For example, the mean bias error (MBE) ranges from −0.51 to 1.29 mm/day, respectively. Study area‐wide, HAR‐85 least represents FAO‐PM during the hottest month and the transitional month (between the wet and dry‐cool seasons) with MBE of 0.65 and 0.70 mm/day, respectively. Conversely, it represents FAO‐PM the most in the wettest month, with smallest MBE of 0.32 mm/day. Beholding this spatiotemporal trait, the final yearly and seasonal adjustment models developed herein enormously moderate the predominant overestimation of the original HAR‐85. The former model explains 46.7% of the error variance whereas 36.9% to 62.3% of the variation in the error is explainable by the latter models. These adjustment models narrow the monthly MBE among the stations from −0.71‐2.17 to −0.80‐1.20 and −0.65‐0.99 mm/day, respectively. Without undermining the accuracy, the year‐round adjustment model can still be feasibly recommended for general use across the study area.
    Description: For the vast area encompassing Sudan and South Sudan, with hyper‐arid, arid, semi‐arid and dry sub‐humid climates, the performance of the simple Hargreaves‐Samani formula is evaluated against FAO Penman‐Monteith method for estimating grass reference evapotranspiration (ETo). ETo is essentially latitude, rainfall, season and timescale dependent with dominant overestimation. Adjustment is proposed through year‐round and seasonal multiple linear regressions on latitude, altitude, longitude and monthly rainfall, explaining ~37‐62% of the bias error.
    Keywords: ddc:551.5 ; arid climates ; evaluation ; FAO Penman‐Monteith method ; grass reference evapotranspiration ; Hargreaves‐Samani method ; sub‐humid climates ; Sudan ; validation
    Language: English
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  • 14
    Publication Date: 2024-02-22
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Recent climate change has brought new patterns of extreme events in terms of both drought and heavy rainfall to the drought‐prone African Sahel. The effects of these recent extreme events on the performance of the Sahel farming systems are still weakly investigated. This study aims at assessing effects of droughts versus floods on crop yield levels and losses, focusing on the so‐called recovery period, particularly 2001–2020. A newly developed productivity‐drought condition index (PDCI) is utilized to assess agricultural productivity as related to drought or flood in a highly vulnerable region, that is, the Sudanese Sahel. Four farming systems, namely traditional rainfed, mechanized rainfed, gravity irrigated and spate irrigated systems, with sorghum and millet as staple food crops, are considered. The PDCI is defined as a function of the integrated normalized difference vegetation index (iNDVI) over the growing season. To address temporal and spatial variabilities, scaling of the PDCI is done in two dimensions: space and time. Crop statistics are used to derive yield losses. Our results show that both drought and flood episodes (seven and six episodes, respectively) can be captured using the PDCI. Drought remains the most relevant risk to Sahel's crop productivity. Some recent large‐scale floods led to yield loss. However, floods cause smaller risks to agricultural productivity compared to droughts. Floods may even result in enhanced crop yields. Based upon scaling in the time or space domain, ranking the severity of drought impacts on crop yield for individual years from 2001 to 2020 reveals least to slightly different results. Vulnerability to drought depends on the crop type and farming system. Drought effect on crop yield from the irrigated sector is clear on individual years but not as a general statistical relationship. The parameter ‘percentage area under drought’ explains around one‐third of the variation in the rainfed crop yield. The spate irrigation scheme, the gravity irrigated system and the rainfed farmlands experienced respectively 87%, 57% and 46% of area under drought on average. Irrigated systems produce much higher crop yields than rainfed systems. The mechanized system is more drought‐vulnerable than the traditional system. These results call for identifying agricultural management pathways that recognize the combined implications of both hydrological extremes for the region's food security.〈/p〉
    Description: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉A newly devised productivity‐drought condition index (PDCI) based on integrated normalized difference vegetation index (iNDVI) data is used to capture the performance of different Sahel farming systems. The performance is evaluated spatially and temporally in a comparative study of effects of droughts versus floods on crop yield levels and losses during 2001–2020. Our research shows that: Crop productivity of all farming systems is severely affected by drought; Flood events can also lead to a decline in productivity, but usually to a much lesser extent; The vulnerability to droughts and floods depends upon the farming system and crop type. Our analysis shows that the farming systems in the Sudanese Sahel have not reverted to conditions that could be described as a Sahel recovery. This study calls for agricultural management decisions, which are specific for the different farming systems, in response to climate variability.〈boxed-text position="anchor" content-type="graphic" id="hyp14978-blkfxd-0001" xml:lang="en"〉 〈graphic position="anchor" id="jats-graphic-1" xlink:href="urn:x-wiley:08856087:media:hyp14978:hyp14978-toc-0001"〉 〈/graphic〉 〈/boxed-text〉〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.1594/PANGAEA.921846
    Description: https://edcintl.cr.usgs.gov/downloads/sciweb1/shared/fews/web/africa/east/dekadal/emodis/ndvi_c6/
    Description: https://earlywarning.usgs.gov/fews/datadownloads/East 20Africa/eMODIS 20NDVI 20C6
    Keywords: ddc:630 ; drought ; farming system ; flood ; normalized difference vegetation index ; performance ; productivity‐drought condition index ; Sahel ; yield loss
    Language: English
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  • 15
    Publication Date: 2024-04-25
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Vegetation classification is an essential prerequisite for understanding vegetation‐water relations at a range of spatial scales. However, in site‐specific applications, such classifications were mostly based on a single Unmanned Aerial Vehicle (UAV) flight, which can be challenging in grasslands and/or herbaceous‐dominated systems, as those communities are small in size and highly mixed. Here, we conducted monthly UAV flights for two years in a riparian wetland in Germany, with acquired imagery used for vegetation classification on a monthly basis under different strategies (with or without auxiliary information from other flights) to increase understanding in ecohydrology. The results show that multi‐flight‐based classification outperformed single‐flight‐based classification due to the higher classification accuracy. Moreover, improved sensitivity of temporal changes in community distribution highlights the benefits of multi‐flight‐based classification ‐ providing a more comprehensive picture of community evolution. From reference to the monthly community distribution, we argue that a combination of two or three flights in early‐ and late‐summer is enough to achieve comparable results to monthly flights, while mid‐summer would be a better timing in case only one flight is scheduled. With such detailed vegetation mapping, we further interpreted the complex spatio‐temporal heterogeneity in NDVI and explored the dominant areas and developmental progress of each community. Impacts from management (mowing events) were also evaluated based on the different responses between communities in two years. Finally, we explored how such vegetation mapping could help understand landscape ecohydrology, and found that the spatio‐temporal distribution of minimal soil moisture was related to NDVI peaks of local community, while grass distribution was explained by both topography and low moisture conditions. Such bi‐directional relationships proved that apart from contributing to an evidence base for wetland management, multi‐flight UAV vegetation mapping could also provide fundamental insights into the ecohydrology of wetlands.〈/p〉
    Description: Chinese Scholarship Council (CSC)
    Description: Einstein Foundation Berlin and Berlin University Alliance
    Description: Leverhulme Trust http://dx.doi.org/10.13039/501100000275
    Keywords: ddc:551.48 ; ecohydrology ; remote sensed vegetation dynamics ; soil moisture ; UAV ; unmanned aerial vehicles ; wetlands
    Language: English
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  • 16
    Publication Date: 2023-12-05
    Description: Computational methods, in particular text‐as‐data or Natural Language Processing (NLP) approaches, have become popular to study climate change communication as a global and large‐scale phenomenon. Scholars have discussed opportunities and challenges of these methods for climate change communication, with some proponents and critics taking strong positions, either embracing the potential of computational methods or critically questioning their value. Mirroring developments in the broader social scientific debate, we aim to bring both sides together by proposing a reflexive, integrative approach for computational research on climate change communication: We reflect on strengths (e.g., making data big and small, nowcasting observations) and weaknesses (e.g., introducing empiricist epistemologies, ignoring biases) of computational approaches. Moreover, we also provide concrete and constructive guidance on when and how to integrate (or not integrate) these methods based on theoretical considerations. We thereby understand computational methods as part of an ever‐increasing, diverse toolbox for analyzing climate change communication.
    Keywords: ddc:304.28 ; big data ; climate change communication ; computational methods ; news media ; social media
    Language: English
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  • 17
    Publication Date: 2023-12-14
    Description: Zooplankton grazing onphytoplankton promotes the release of particulate and dissolved organic matter (DOM) into the water column and therefore plays a key role in organic matter cycling in aquatic systems. Prokaryotes are the main DOM consumers in the ocean by actively remineralizing and transforming it, contributing to its molecular diversification. To explore the molecular composition of zooplankton‐derived DOM and its bioavailability to natural prokaryotic communities, the DOM generated by a mixed zooplankton community in the coastal Atlantic off Spain was used as substrate for a natural prokaryotic community and monitored over a ~ 5‐d incubation experiment. The molecular composition of solid‐phase extracted DOM was characterized via Fourier‐transform ion cyclotron resonance mass spectrometry. After ~ 4 d in the zooplankton‐derived DOM amended incubation, the prokaryotic community demonstrated a 17‐fold exponential increase in cell number. The prokaryotic growth resulted in a reduction in bulk dissolved organic carbon concentration and the zooplankton‐derived DOM was considerably transformed at molecular and bulk elemental levels over the incubation period. The C : N ratio (calculated from the obtained molecular formulae) increased while the functional diversity decreased over the incubation time. In addition, molecular indices pointed to a reduced bioavailability of DOM at the end of the experiment. These findings show that zooplankton excreta are a source of labile organic matter that is quickly metabolized by the prokaryotic community. Therefore, a fraction of carbon is shunted from transfer to secondary consumers similarly to the viral shunt, suggesting that the zooplankton–prokaryotic interactions play an important role in the ocean's carbon cycle.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Xunta de Galicia http://dx.doi.org/10.13039/501100010801
    Keywords: ddc:577.7 ; Spain ; coastal Atlantic ; zooplankton–prokaryotic interactions ; ocean’s carbon cycle
    Language: English
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  • 18
    Publication Date: 2023-12-14
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The collection of zooplankton swimmers and sinkers in time‐series sediment traps provides unique insight into year‐round and interannual trends in zooplankton population dynamics. These samples are particularly valuable in remote and difficult to access areas such as the Arctic Ocean, where samples from the ice‐covered season are rare. In the present study, we investigated zooplankton composition based on swimmers and sinkers collected by sediment traps at water depths of 180–280, 800–1320, and 2320–2550 m, over a period of 16 yr (2000–2016) at the Long‐Term Ecological Research observatory HAUSGARTEN located in the eastern Fram Strait (79°N, 4°E). The time‐series data showed seasonal and interannual trends within the dominant zooplankton groups including copepoda, foraminifera, ostracoda, amphipoda, pteropoda, and chaetognatha. Amphipoda and copepoda dominated the abundance of swimmers while pteropoda and foraminifera were the most important sinkers. Although the seasonal occurrence of these groups was relatively consistent between years, there were notable interannual variations in abundance, suggesting the influence of various environmental conditions such as sea‐ice dynamic and lateral advection of water masses, for example, meltwater and Atlantic water. Statistical analyses revealed a correlation between the Arctic dipole climatic index and sea‐ice dynamics (i.e., ice coverage and concentration), as well as the importance of the distance from the ice edge on swimmer composition patterns and carbon export.〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Federal Ministry of Education and Research (BMBF)
    Description: Helmholtz‐Gemeinschaft
    Keywords: ddc:577.7 ; eastern Fram Strait ; sea ice dynamics ; zooplankton population dynamics
    Language: English
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  • 19
    Publication Date: 2023-01-14
    Description: The Paris Agreement marks a significant milestone in international climate politics. With its adoption, Parties call for non‐ and sub‐state actors to contribute to the global climate agenda and close the emissions gap left by states. Such a facilitative setting embraces non‐state climate action through joint efforts, synergies, and different modes of collaboration. At the same time, non‐state actors have always played a critical and confrontational role in international climate governance. Based on a systematic literature review, we identify and critically assess the role of non‐state climate action in a facilitative post‐Paris climate governance regime. We thereby highlight three constitutive themes, namely different state‐non‐state relations, competing level of ambition, and a variety of knowledge foundations. We substantiate these themes, derived from an inductive analysis of existing literature, with illustrative examples and propose three paradigmatic non‐state actor roles in post‐Paris climate governance on a continuum between compliance and critique. We thereby highlight four particular threats of a facilitative setting, namely substitution of state action, co‐optation, tokenism, and depoliticization. Future research should not limit itself to an effective integration of NSSAs into a facilitative climate regime, but also engage with the merits of contestation. This article is categorized under: Policy and Governance 〉 Multilevel and Transnational Climate Change Governance
    Description: Three constitutive themes—different state‐non‐state relations, levels of ambition, and knowledge foundations—define the multiple roles non‐ and sub‐state actors can occupy in the post‐Paris climate governance regime. Yet, calls for voluntary, collaborative, and synergetic non‐state climate action in a facilitative post‐Paris climate governance setting run the risk to overshadow fundamental tensions when governing climate change.
    Description: Svenska Forskningsrådet Formas http://dx.doi.org/10.13039/501100001862
    Description: Deutsche Forschungsgemeinschaft (DFG)
    Keywords: ddc:341.7 ; climate change governance ; contestation ; environmental politics ; non‐state actors ; Paris Agreement ; transformation
    Language: English
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  • 20
    Publication Date: 2023-01-15
    Description: A limited number of gauging stations, especially for nested catchments, hampers a process understanding of the interaction between streamflow, groundwater and water usage during drought. Non‐commercial measurement devices can help overcome this lack of monitoring, but they need to be thoroughly tested. The Dreisam River in the South‐West of Germany was affected by several hydrological drought events from 2015 to 2020 during which parts of the main stream and tributaries fell dry. Therefore it provided a useful case study area for a flexible longitudinal water quality and quantity monitoring network. Among other measurements the setup employs an image‐based method with QR codes as fiducial marker. In order to assess under which conditions the QR‐code based water level loggers (WLL) deliver data according to scientific standards, we compared its performance to conventional capacitive based WLL. The results from 20 monitoring stations reveal that the riverbed was dry for 〉50% at several locations and even for 〉70% at most severely affected locations during July and August 2020, with the north western parts of the catchment being especially concerned. Highly variable longitudinal drying patterns of the stream reaches emerged from the monitoring. The image‐based method was found valuable for identification and validation of zero level occurrences. Nevertheless, a simple image processing approach (based on an automatic thresholding algorithm) did not compensate for errors due to natural conditions and technical setup. Our findings highlight that the complexity of measurement environments is a major challenge when working with image‐based methods.
    Description: We monitored zero water levels in a meso‐scale catchment with temperate climate by means of image‐based and conventional water level logging techniques. A detailed analysis of the longitudinal drying patterns enables a discussion about hydrological connectivity and the processes influencing the drying.
    Description: Badenova Fund For Innovation
    Description: https://doi.org/10.6094/UNIFR/228702
    Keywords: ddc:551.48 ; hydrological drought ; innovative sensors ; longitudinal connectivity ; stream reaches ; streamflow intermittency ; zero flow
    Language: English
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  • 21
    Publication Date: 2023-01-15
    Description: Physiological sensitivity of cold‐water corals to ocean change is far less understood than of tropical corals and very little is known about the impacts of ocean acidification and warming on degradative processes of dead coral framework. In a 13‐month laboratory experiment, we examined the interactive effects of gradually increasing temperature and pCO2 levels on survival, growth, and respiration of two prominent color morphotypes (colormorphs) of the framework‐forming cold‐water coral Lophelia pertusa, as well as bioerosion and dissolution of dead framework. Calcification rates tended to increase with warming, showing temperature optima at ~ 14°C (white colormorph) and 10–12°C (orange colormorph) and decreased with increasing pCO2. Net dissolution occurred at aragonite undersaturation (ΩAr 〈 1) at ~ 1000 μatm pCO2. Under combined warming and acidification, the negative effects of acidification on growth were initially mitigated, but at ~ 1600 μatm dissolution prevailed. Respiration rates increased with warming, more strongly in orange corals, while acidification slightly suppressed respiration. Calcification and respiration rates as well as polyp mortality were consistently higher in orange corals. Mortality increased considerably at 14–15°C in both colormorphs. Bioerosion/dissolution of dead framework was not affected by warming alone but was significantly enhanced by acidification. While live corals may cope with intermediate levels of elevated pCO2 and temperature, long‐term impacts beyond levels projected for the end of this century will likely lead to skeletal dissolution and increased mortality. Our findings further suggest that acidification causes accelerated degradation of dead framework even at aragonite saturated conditions, which will eventually compromise the structural integrity of cold‐water coral reefs.
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Marine Research in Ireland
    Description: French National Research Agency http://dx.doi.org/10.13039/501100001665
    Keywords: ddc:577.7 ; cold-water corals ; ocean change ; laboratory experiments ; framwork dissolution ; bioerosion
    Language: English
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  • 22
    Publication Date: 2023-01-25
    Description: The gap between the internationally agreed climate objectives and tangible emissions reductions looms large. We explore how the supreme decision‐making body of the United Nations Framework Convention on Climate Change (UNFCCC), the Conference of the Parties (COP), could develop to promote more effective climate policy. We argue that promoting implementation of climate action could benefit from focusing more on individual sectoral systems, particularly for mitigation. We consider five key governance functions of international institutions to discuss how the COP and the sessions it convenes could advance implementation of the Paris Agreement: guidance and signal, rules and standards, transparency and accountability, means of implementation, and knowledge and learning. In addition, we consider the role of the COP and its sessions as mega‐events of global climate policy. We identify opportunities for promoting sectoral climate action across all five governance functions and for both the COP as a formal body and the COP sessions as conducive events. Harnessing these opportunities would require stronger involvement of national ministries in addition to the ministries of foreign affairs and environment that traditionally run the COP process, as well as stronger involvement of non‐Party stakeholders within formal COP processes. This article is categorized under: Policy and Governance 〉 International Policy Framework
    Description: The UN climate conferences can drive implementation across five governance functions, using both their roles as formal decision‐making body and as mega‐events.
    Description: German Federal Ministry for Economic Cooperation and Development (BMZ)
    Keywords: climate regime ; Conference of the Parties ; COP ; UNFCCC
    Language: English
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  • 23
    Publication Date: 2022-12-07
    Description: The fluorophore [2‐(4‐pyridyl)‐5{[4‐dimethylaminoethyl‐aminocarbamoyl‐methoxy]phenyl}oxazole], in short PDMPO, is incorporated in newly polymerized silica in diatom frustules and thereby provides a tool to estimate Si uptake, study diatom cell cycles but also determine mortality‐independent abundance‐based species specific‐growth rates in cultures and natural assemblages. In this study, the theoretical framework and applicability of the PDMPO staining technique to estimate diatom species specific‐growth rates were investigated. Three common polar diatom species, Pseudo‐nitzschia subcurvata, Chaetoceros simplex, and Thalassiosira sp., chosen in order to cover a broad range of species specific frustule and life‐cycle characteristics, were incubated over 24 h in control (no PDMPO) and with 0.125 and 0.6 μM PDMPO addition, respectively. Results indicate that specific‐growth rates of the species tested were not affected in both treatments with PDMPO addition. The specific‐growth rate estimates based on the PDMPO staining patterns (μPDMPO) were comparable and more robust than growth rates estimated from the changes in cell concentrations (μcc). This technique also allowed to investigate and highlight the importance of the illumination cycle (light and dark phases) on cell division in diatoms.
    Keywords: ddc:579.8 ; diatom frustules ; Si uptake ; growth rate estimation
    Language: English
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  • 24
    Publication Date: 2022-06-26
    Description: The two small research catchments Obere Brachtpe (2.6 km2; 50.989986, 7.752013) and Bohlmicke (1 km2, 51.079319, 7.892988) are located in the Rhenish Massif, a low mountain range in Germany. Land use in both catchments is dominated by pasture land, spruce stands and mixed forests. Mean annual temperature is 9.1°C, and mean annual total precipitation is 1250 mm, with 15%–20% of the annual precipitation falling as snow. The geology is characterized by sandy silty clay shale from the Lower and Middle Devonian. Loamy Cambisols derived from periglacial slope deposits, complemented by Leptosols and Stagnosols, are the most prominent soils in the catchments. Long‐term hydrological datasets of precipitation, throughfall, discharge, groundwater levels and soil moisture (at different soil depths) in a high temporal and spatial resolution are available for further scientific analysis. Both catchments were monitored within the time period 1999 and 2009, in order to understand how the antecedent soil moisture, stratified soils (periglacial cover beds) and topography (slope form) impacted the subsurface connectivity, and the subsurface stormflow generation ‐ a dominant runoff generation process in humid mountainous catchments. Detailed physically based investigations on runoff processes were carried out, and the obtained results helped to better understand subsurface stormflow generation and subsurface connectivity dynamics. The process knowledge gained, which was presented at several conferences, as well as publications, was the basis for the discussion of open questions within the scientific network ‘Subsurface Stormflow ‐ A well‐recognized, but still challenging process in Catchment Hydrology’ (2016–2021), and the research unit ‘Fast and invisible: conquering subsurface stormflow through an interdisciplinary multisite approach’ (2022–2025), both financed by the German Research Foundation (DFG).
    Description: Long‐term hydrological datasets of precipitation, throughfall, discharge, groundwater levels and soil moisture (at different soil depths) in a high temporal and spatial resolution are available of the two small catchments Obere Brachtpe (2.6 km²) and Bohlmicke (1 km²) (Germany). Both catchments have been monitored in order to understand how the antecedent soil moisture, stratified soils (periglacial cover beds) and topography (slope form) impacted the subsurface connectivity and the subsurface stormflow generation in humid mountainous catchments.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:551.48
    Language: English
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  • 25
    Publication Date: 2022-06-28
    Description: Statistical and climate models are frequently used for biodiversity projections under future climatic changes, but their predictive capacity for freshwater plankton may vary among different species and community metrics. Here, we used random forests to model plankton species and community metrics as a function of biological, climatic, physical, and chemical data from long‐term (2000–2017) monitoring data collected from Lake Müggelsee Berlin, Germany. We (1) compared the predictability of well‐known lake plankton metric types (biomass, abundance, taxonomic diversity, Shannon diversity, Simpson diversity, evenness, taxonomic distinctness, and taxonomic richness) and (2) assessed how the relative influence of different environmental drivers varies across lake plankton metric models. Overall, the metric predictability was highest for biomass and abundance followed by taxonomic richness. The biomass of dominant phytoplankton taxonomic groups such as cyanobacteria (adjusted‐R2 = 0.53) and the abundance of dominant zooplankton taxonomic groups such as rotifers (adjusted‐R2 = 0.59) and daphnids (adjusted‐R2 = 0.51) were more predictable than other metric types. The plankton metric predictability increased when grouping phytoplankton species according to their functional traits (adjusted‐R2 = 0.37 ± 0.14, mean ± SD, n = 36 functional groups) compared to higher taxonomic units (adjusted‐R2 = 0.25 ± 0.15, n = 22 taxonomic groups). Light, nutrients, water temperature, and seasonality for phytoplankton and food resources for zooplankton were the main drivers of both taxonomic and functional groups, giving confidence that our models captured the expected major environmental drivers. Our quantitative analyses highlight the multidimensionality of lake planktonic responses to environmental drivers and have implications for our capacity to select appropriate metrics for forecasting the future of lake ecosystems under global change scenarios.
    Description: European Union's Horizon 2020 Research and Innovation Programme
    Description: Belmont Forum
    Description: BiodivERsA
    Description: LimnoSCenES
    Keywords: ddc:579.17
    Language: English
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  • 26
    Publication Date: 2022-10-08
    Description: Many lake ecosystems that have been severely disturbed by eutrophication, have also experienced large human efforts to restore “natural” conditions. However, the trajectories and the extent of recovery of these lake ecosystems are still poorly understood. In many shallow lakes, recovery was often delayed and counter‐clockwise hysteretic. Here, we study recovery and ecosystem trajectories in a large and deep lake using diatom remains in sediment cores and time series of phosphorus concentrations. We identified four periods of diatom community change: slow change during early eutrophication, thereafter a short period of rapid change after the 1950s, followed by community stability from the 1960s to the mid‐1980s, and finally a recovery phase until 2010. Diatom community structure responded quickly and in a saturating way to increasing phosphorus concentrations, but also fast to phosphorus decline. Hence, diatom community dynamics did not show counter‐clockwise hysteresis but was characterized by a high degree of recovery and clock‐wise hysteresis (CWH). We suggest that CWH in response to eutrophication and recovery is a typical and previously overlooked feature of deep lakes, which results from a more rapid change of average nutrient concentrations and thus productivity in the epilimnion compared to average nutrient concentrations across the entire water column. Such nonlinear and hysteretic responses to changing nutrients need to be considered when analyzing the effects of other stressors such as climate warming on ecosystem dynamics to prevent erroneous attribution of ecosystem change to other stressors instead of nutrient change.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: European Regional Development Fund http://dx.doi.org/10.13039/501100008530
    Keywords: ddc:577.63
    Language: English
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  • 27
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    John Wiley & Sons, Inc. | Hoboken, USA
    Publication Date: 2022-08-05
    Description: In‐depth understanding of the potential implications of climate change is required to guide decision‐ and policy‐makers when developing adaptation strategies and designing infrastructure suitable for future conditions. Impact models that translate potential future climate conditions into variables of interest are needed to create the causal connection between a changing climate and its impact for different sectors. Recent surveys suggest that the primary strategy for validating such models (and hence for justifying their use) heavily relies on assessing the accuracy of model simulations by comparing them against historical observations. We argue that such a comparison is necessary and valuable, but not sufficient to achieve a comprehensive evaluation of climate change impact models. We believe that a complementary, largely observation‐independent, step of model evaluation is needed to ensure more transparency of model behavior and greater robustness of scenario‐based analyses. This step should address the following four questions: (1) Do modeled dominant process controls match our system perception? (2) Is my model's sensitivity to changing forcing as expected? (3) Do modeled decision levers show adequate influence? (4) Can we attribute uncertainty sources throughout the projection horizon? We believe that global sensitivity analysis, with its ability to investigate a model's response to joint variations of multiple inputs in a structured way, offers a coherent approach to address all four questions comprehensively. Such additional model evaluation would strengthen stakeholder confidence in model projections and, therefore, into the adaptation strategies derived with the help of impact models.
    Description: A comprehensive evaluation of climate change impact models combining both observation‐based and response‐based strategies.
    Description: This article is categorized under: Climate Models and Modeling 〉 Knowledge Generation with Models Assessing Impacts of Climate Change 〉 Evaluating Future Impacts of Climate Change
    Description: Alexander von Humboldt‐Stiftung http://dx.doi.org/10.13039/100005156
    Description: Engineering and Physical Sciences Research Council http://dx.doi.org/10.13039/501100000266
    Keywords: ddc:551.6
    Language: English
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  • 28
    Publication Date: 2022-10-01
    Description: Bacteria play a key role in sustaining the chemodiversity of marine dissolved organic matter (DOM), yet there is limited direct evidence of a major contribution of bacterial exometabolites to the DOM pool. This study tests whether molecular formulae of intact exometabolites can be detected in natural DOM via untargeted Fourier‐transform ion cyclotron resonance mass spectrometry (FT‐ICR‐MS). We analyzed a series of quantitative mixtures of solid‐phase extracted DOM from the deep ocean, of a natural microbial community and selected model strains of marine bacteria. Under standard instrument settings (200 broadband scans, mass range 92–1000 Da), 77% of molecular formulae were shared between the mesocosm and marine DOM. However, there was 〈 10% overlap between pure bacterial exometabolome with marine DOM, and in mixing ratios closest to mimicking natural environments (1% bacterial DOM, 99% marine DOM), only 4% of the unique bacterial exometabolites remained detectable. Further experiments with the bacterial exometabolome DOM mixtures using enhanced instrument settings resulted in increased detection of the exometabolites at low concentrations. At 1000 and 10,000 accumulated scans, 23% and 29% of the unique molecular formulae were detectable at low concentrations, respectively. Moreover, windowing a specific mass range encompassing a representative fraction of exometabolites tripled the number of unique detected formulae at low concentrations. Routine FT‐ICR‐MS settings are thus not always sufficient to distinguish bacterial exometabolome patterns from a seawater DOM background. To observe these patterns at higher sensitivity, we recommend a high scan number coupled with windowing a characteristic region of the molecular fingerprint.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:551.46 ; ddc:579.3 ; ddc:
    Language: English
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  • 29
    Publication Date: 2022-10-04
    Description: The latest version of the Soil and Water Assessment Tool (SWAT+) features several improvements compared with previous versions of the model, for example, the definition of landscape units that allow for a better representation of spatio‐temporal dynamics. To evaluate the new model capabilities in lowland catchments characterized by near‐surface groundwater tables and extensive tile drainage, we assess the performance of two SWAT+ model setups in comparison to a setup based on a previous SWAT model version (SWAT3S with a modified three groundwater storage model) in the Kielstau catchment in Northern Germany. The Kielstau catchment has an area of about 50 km2, is dominated by agricultural land use, and has been thoroughly monitored since 2005. In both SWAT+ setups, the catchment is divided into upland areas and floodplains, but in the first SWAT+ model setup, runoff from the hydrologic response units is summed up at landscape unit level and added directly to the stream. In the second SWAT+ model setup, runoff is routed across the landscape before it reaches the streams. Model results are compared with regard to (i) model performance for stream flow at the outlet of the catchment and (ii) aggregated as well as temporally and spatially distributed water balance components. All three model setups show a very good performance at the catchment outlet. In comparison to a previous version of the SWAT model that produced more groundwater flow, the SWAT+ model produced more tile drainage flow and surface runoff. Results from the new SWAT+ model confirm that the representation of routing processes from uplands to floodplains in the model further improved the representation of hydrological processes. Particularly, the stronger spatial heterogeneity that can be related to characteristics of the landscape, is very promising for a better understanding and model representation of hydrological fluxes in lowland areas. The outcomes of this study are expected to further prove the applicability of SWAT+ and provide useful information for future model development.
    Description: The model performance of all three model setups was very good, but the SWAT+ model setup with runoff routing between landscape units performed best. Moreover, the SWAT+ model applications predicted a greater spatial heterogeneity of the water balance components. The representation of hydrological fluxes particularly with regard to groundwater flow, surface runoff, and tile drainage flow differed considerably between the SWAT and SWAT+ model setups.
    Keywords: ddc:551.48
    Language: English
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  • 30
    Publication Date: 2022-10-04
    Description: Pelagic bacteria can be classified into free‐living and particle‐attached life modes, which either dwell in the water column or attach to suspended particles. Bacteria with a generalist life style, however, can actively shift between these two habitats. Globally increasing densities of natural and artificial particles enhance habitat heterogeneity, with potential consequences for system stability and trophic transfer through aquatic food webs. To better decipher the dynamics of microbial communities, we investigated the influence of adaptive vs. fixed habitat choice on species coexistence for a simplified bacterial community by analyzing a corresponding food web model, consisting of two specialist bacterial prey species (free and attached), a generalist bacterial prey species with the ability to shift between both habitats, and two protist predators, specialized on either water or particle compartment. For simplicity we assume a shared resource pool, considering particles only for colonization but not as a source for nutrients or carbon, that is, inert particles like microplastics or inorganic sediments. The model predicts coexistence on a cyclic attractor between fixed and flexible bacteria, if the costs for adaptive habitat choice can be balanced by adaptation speed. The presence of adaptive prey dampens predator–prey cycle amplitudes, contributing to system stabilization resulting in higher mean predator biomass compared to specialist prey only. Thus, in pelagic microbial systems, flexible habitat choice at the prey level has important implications for system stability and magnitude of energy flow through the microbial loop.
    Description: German Ministry of Education and Science
    Description: German Science Foundation (DFG)
    Keywords: ddc:579.3
    Language: English
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  • 31
    Publication Date: 2022-10-04
    Description: Greenhouse gas fluxes (CO2, CH4, and N2O) from African streams and rivers are under‐represented in global datasets, resulting in uncertainties in their contributions to regional and global budgets. We conducted year‐long sampling of 59 sites in a nested‐catchment design in the Mara River, Kenya in which fluxes were quantified and their underlying controls assessed. We estimated annual basin‐scale greenhouse gas emissions from measured in‐stream gas concentrations, modeled gas transfer velocities, and determined the sensitivity of up‐scaling to discharge. Based on the total annual CO2‐equivalent emissions calculated from global warming potentials (GWP), the Mara basin was a net greenhouse gas source (294 ± 35 Gg CO2 eq yr−1). Lower‐order streams (1–3) contributed 81% of the total fluxes, and higher stream orders (4–8) contributed 19%. Cropland‐draining streams also exhibited higher fluxes compared to forested streams. Seasonality in stream discharge affected stream widths (and stream area) and gas exchange rates, strongly influencing the basin‐wide annual flux, which was 10 times higher during the high and medium discharge periods than the low discharge period. The basin‐wide estimate was underestimated by up to 36% if discharge was ignored, and up to 37% for lower stream orders. Future research should therefore include seasonality in stream surface areas in upscaling procedures to better constrain basin‐wide fluxes. Given that agricultural activities are a major factor increasing riverine greenhouse gas fluxes in the study region, increased conversion of forests and agricultural intensification has the possibility of increasing the contribution of the African continent to global greenhouse gas sources.
    Description: Deutscher Akademischer Austauschdienst http://dx.doi.org/10.13039/501100001655
    Description: IHE Delft Institute for Water Education
    Description: Federal Ministry of Education and Research http://dx.doi.org/10.13039/501100002347
    Description: Helmholtz Association http://dx.doi.org/10.13039/501100009318
    Description: TERENO Bavarian Alps/ Pre‐Alps Observatory
    Keywords: ddc:551
    Language: English
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  • 32
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    Unknown
    John Wiley & Sons, Inc. | Hoboken, USA
    Publication Date: 2022-10-05
    Description: How will the theories and practices of democracy fare in a climate changing world? Are conventional democratic institutions ultimately doomed or are they able to become more responsive to a changing climate? Is there a need to reimagine democracy and how might it be reimagined? This article reviews the different responses to these questions by distinguishing between three “political imaginaries” in which the relationship between climate change and democracy takes distinct forms. I start by showing how the concept of “political imaginaries” can facilitate the comparison of the different ways in which the relation between democracy and climate change is constructed, before reviewing three such imaginaries. The skeptical imaginary, found in the “eco‐authoritarianism” of the 1970s that is echoed by much sociopolitical analysis today, casts doubt on the possibilities of democratic mechanisms to respond adequately and swiftly to the problem of climate change. Those who resist such skepticism often defend democracy by arguing that institutions and processes of democracy can be made more “ecologically rational”—the rational imaginary of climate democracy involves improvements in political representation and participation. Finally, I present the alternative radical democratic imaginary, in which the crisis of climate change provides a moment for the rupture of existing sociopolitical structures and the formation of alternatives. The article concludes that although none of these imaginaries is able to capture the entirety of climate change politics around the world, the radical democratic imaginary is responsive to the inevitable and valuable plurality around the issue of climate change. This article is categorized under: Climate, Nature, and Ethics 〉 Ethics and Climate Change Policy and Governance 〉 Multilevel and Transnational Climate Change Governance
    Description: Climate protests may mobilise new political subjects.
    Keywords: ddc:363.70561
    Language: English
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  • 33
    Publication Date: 2022-10-06
    Description: In recent years, the issue of high groundwater levels has caught attention. Unfavorable consequences of high groundwater levels are especially damage to buildings, infrastructure, and the environment. Processes that lead to high groundwater levels are hydrological (heavy or extended rainfall and flood events), or anthropogenic (reduced groundwater extractions, interaction with sewer networks, hydraulic engineering measures, structural interventions in the water balance, and mining activities). Several different map products have been prepared for the information of inhabitants and for planning purposes, and also methods for damage and risk analysis related to high groundwater levels have been developed. Groundwater management measures and structural measures are available to reduce the risk related to high groundwater levels. An operational management system could be combined from existing components, but operational forecasting systems for high groundwater levels are—different to flood forecasting systems—not yet common practice. A better understanding of the processes and the development of integrated approaches for modeling, design, planning, forecasting, and warning, as well as improvement of interdisciplinary collaboration between different organizations, are recommendations for the future. This article is categorized under: Engineering Water 〉 Engineering Water Water and Life 〉 Conservation, Management, and Awareness Science of Water 〉 Hydrological Processes Science of Water 〉 Water Extremes
    Description: Pumping water from a basement during the Neiße flood 2010 in Saxony. The clear water indicates that the basement flooding originates from groundwater (photo: Reinhard Schinke).
    Keywords: ddc:551.49
    Language: English
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  • 34
    Publication Date: 2022-09-25
    Description: The Ghohroud granitoids (GG), containing mafic microgranular enclaves (MMEs) are located in the central part of the Urumieh‐Dokhtar Magmatic Arc (UDMA) in central Iran. They are associated with the subduction‐related magmatism in the Alpine‐Himalayan orogenic belt. The GG are comprised of a variety of intermediate and felsic rocks, including tonalite, granodiorite, granite, diorite porphyry and monzodiorite. The MMEs are gabbroic diorite and tonalite in composition and characterized by a fine‐grained hypidiomorphic microgranular texture with occasional chilled margins. They show rounded, sharp or irregular contact with the host granitoids. The occurrences of quartz, K‐feldspar and corroded plagioclase indicate that MMEs are the products of mixing between mantle and crust‐derived magmas. New ages of zircon U–Pb dating reveal that the GG in the Kashan area emplaced at ca. 19–17 Ma (Burdigalian). All the samples of MMEs and granitoid host rocks in this study are metaluminous and calc‐alkaline with I‐type affinities. They are enriched in light rare earth elements (LREEs) and show slight negative Eu anomalies (Eu/Eu* = 0.36–0.95). These features in a combination with the relative depletion in Nb, Ta, Ti and P, indicate the granitoids and MMEs are closely associated with subduction‐related magmas at an active continental margin. The host rocks yield relatively homogeneous isotopic compositions of initial 87Sr/86Sr ratios ranging from 0.706036 to 0.707055, εNd(t) values varying from −2.25 to 0.8, and the Nd model ages (TDM) vary in a limited range of 0.70–0.96 Ga. The MMEs show similar initial 87Sr/86Sr ratios (0.706420–0.707366), εNd(t) values (−1.32 to −0.27), TDM (0.68–1.09 Ga) and Pb isotopic compositions with host granitoids, which imply they attained isotopic equilibration during magma mingling and mixing. In combination with the petrographic, chemical and isotopic results, we suggest that the origin of MMEs and their host rocks were related to the interaction between crust‐derived melts and mantle‐derived mafic magmas. The magma‐mixing event possibly occurred during the transition from subduction to collision in the UDMA along with the closure of the Neotethyan ocean.
    Description: A comprehensive dataset from petrographic characteristics to geochemical compositions of the mafic microgranular enclaves and granitoid host rocks from the Urumieh–Dokhtar Magmatic Arc (Iran) was presented. The new data provide significant insight into the evolution of magmatism in this area, which was tightly related to the Neotethyan closure. image
    Description: National Nature Science Foundation of China
    Description: TMU Research Grant Council
    Keywords: ddc:552.3
    Language: English
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  • 35
    Publication Date: 2022-09-22
    Description: Arctic and alpine aquatic ecosystems are changing rapidly under recent global warming, threatening water resources by diminishing trophic status and changing biotic composition. Macrophytes play a key role in the ecology of freshwaters and we need to improve our understanding of long‐term macrophytes diversity and environmental change so far limited by the sporadic presence of macrofossils in sediments. In our study, we applied metabarcoding using the trnL P6 loop marker to retrieve macrophyte richness and composition from 179 surface‐sediment samples from arctic Siberian and alpine Chinese lakes and three representative lake cores. The surface‐sediment dataset suggests that macrophyte richness and composition are mostly affected by temperature and conductivity, with highest richness when mean July temperatures are higher than 12°C and conductivity ranges between 40 and 400 μS cm−1. Compositional turnover during the Late Pleistocene/Holocene is minor in Siberian cores and characterized by a less rich, but stable emergent macrophyte community. Richness decreases during the Last Glacial Maximum and rises during wetter and warmer climate in the Late‐glacial and Mid‐Holocene. In contrast, we detect a pronounced change from emergent to submerged taxa at 14 ka in the Tibetan alpine core, which can be explained by increasing temperature and conductivity due to glacial runoff and evaporation. Our study provides evidence for the suitability of the trnL marker to recover modern and past macrophyte diversity and its applicability for the response of macrophyte diversity to lake‐hydrochemical and climate variability predicting contrasting macrophyte changes in arctic and alpine lakes under intensified warming and human impact.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: National Natural Science Foundation of China http://dx.doi.org/10.13039/501100001809
    Description: Second Tibetan Plateau Scientific Expedition and Research Program
    Description: https://doi.pangaea.de/10.1594/PANGAEA.920866
    Description: https://doi.org/10.5061/dryad.k6djh9w4r
    Keywords: ddc:577.63
    Language: English
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  • 36
    Publication Date: 2022-06-17
    Description: Urban green space is increasingly viewed as essential infrastructure to build resilience to climate change by retaining water in the city landscape and balancing ecohydrological partitioning into evapotranspiration for cooling and groundwater recharge. Quantifying how different vegetation types affect water partitioning is essential for future management, but paucity of data and the complex heterogeneity of urban areas make water balance estimates challenging. Here, we provide a preliminary assessment of water partitioning from different sized patches of trees and grass as well as from sealed surfaces. To do this, we used limited field observations together with an advanced, process‐based tracer‐aided ecohydrological model at a meso‐scale (5 km2) in central Berlin, Germany. Transpiration was the dominant green water flux accounting for over 50% of evapotranspiration in the modelled area. Green water fluxes were in general greater from trees compared with grass, but grass in large parks transpired more water compared with grass in small parks that were intensively used for recreation. Interception evaporation was larger for trees compared with grass, but soil water evaporation was greater for grass compared with trees. We also show that evapotranspiration from tree‐covered areas comprise almost 80% of the total evapotranspiration from the whole model domain while making up less than 30% of the surface cover. The results form an important stepping‐stone towards further upscaling over larger areas and highlights the importance of continuous high‐resolution hydrological measurements in the urban landscape, as well as the need for improvements to ecohydrological models to capture important urban processes.
    Description: Berlin University Alliance / Einstein Stiftung Berlin, Climate and Water under Change
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Einstein Stiftung Berlin http://dx.doi.org/10.13039/501100006188
    Description: Leverhulme Trust http://dx.doi.org/10.13039/501100000275
    Description: Urban Climate Observatory (UCO) Berlin
    Keywords: ddc:551.49
    Language: English
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  • 37
    Publication Date: 2022-08-09
    Description: Iron flocculants play a major role in the remediation of water bodies, removing particulate pollutants such as microplastics through floc formation. Such flocs are prone to microbial iron reduction while lying on top of anoxic sediments, which possibly leads the release of bound microplastics. In this study, Shewanella oneidensis was employed to simulate the impact of microbial iron reduction on the release of polyethylene spheres from sunken flocs in 120 d batch experiments. Most of the flocs iron (oxyhydr)oxides were reduced (70–90%), but this did not affect their integrity. Only a negligible proportion (0.2–2.7%) of polyethylene spheres was released, while the majority remained bound inside the floc matrix. This study exemplifies that flocs are quite stable, even when experiencing microbial iron reduction under anoxic conditions. Thereby incorporation into such aggregates may display a potential mode of long‐term microplastics storage in freshwater sediments.
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: https://doi.org/10.48758/ufz.11330
    Keywords: ddc:363.73 ; ddc:551.303
    Language: English
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  • 38
    Publication Date: 2022-11-01
    Description: The pelagic ecosystem of the Arctic Ocean is threatened by severe changes such as the reduction in sea‐ice coverage and increased inflow of warmer Atlantic water. The latter is already altering the zooplankton community, highlighting the need for monitoring studies. It is therefore essential to accelerate the taxonomic identification to speed up sample analysis, and to expand the analysis to biomass and size assessments, providing data for modeling efforts. Our case study in Fram Strait illustrates that image‐based analyses with the ZooScan provide abundance data and taxonomic resolutions that are comparable to microscopic analyses and are suitable for zooplankton monitoring purposes in the Arctic. We also show that image analysis allows to differentiate developmental stages of the key species Calanus spp. and Metridia longa and, thus, to study their population dynamics. Our results emphasize that older preserved samples can be successfully reanalyzed with ZooScan. To explore the applicability of image parameters for calculating total mesozooplankton and Calanus spp. biomasses, we used (1) conversion factors (CFs) translating wet mass to dry mass (DM), and (2) length–mass (LM) relationships. For Calanus spp., the calculated biomass values yielded similar results as direct DM measurements. Total mesozooplankton biomass ranged between 1.6 and 15 (LM) or 2.4 and 21 (CF) g DM m², respectively, which corresponds to previous studies in Fram Strait. Ultimately, a normalized biomass size spectra analysis provides 1st insights into the mesozooplankton size structure at different depths, revealing steep slopes in the linear fit in communities influenced by Atlantic water inflow.
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Keywords: ddc:577.7
    Language: English
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  • 39
    Publication Date: 2023-01-27
    Description: Interactions between phytoplankton species shape their physiological and evolutionary responses. Yet, studies addressing the evolutionary responses of phytoplankton in changing environments often lack an explicit element of biotic interactions. Here, we ask (1) how the presence of a locally adapted phytoplankton species will affect an invading phytoplankton species' evolutionary response to a physiologically challenging environment; (2) whether this response is conserved across environments varying in quality; and (3) which traits are associated with being a successful invader under climate change scenarios. In a conceptual first step to disentangle these broad questions, we experimentally evolved populations of fresh‐ and seawater phytoplankton in a novel salinity (the freshwater green algae Chlamydomonas in salt water, and the marine Ostreococcus in freshwater), either as mono‐cultures (colonizers) or as co‐cultures (invaders: invading a novel salinity occupied by a resident species, for example, Chlamydomonas invading salt water occupied by resident Ostreococcus) for 200 generations. We superimposed a temperature treatment (control (22°C), mild warming (26°C), drastic warming (32°C), and fluctuating (22°C/32°C) warming) as a representative aspect of climate change with the potential to ameliorate or deteriorate existing environmental conditions. Invaders had systematically lower extinction rates and evolved overall higher growth rates, as well as broader salinity and temperature preferences than colonizers. The invading species' evolutionary responses differed from those of colonizers in a replicable way across environments of differing quality. The evolution of small cell size and high reactive oxygen species tolerance may explain the invaders' higher fitness under the scenarios tested here.
    Description: British Ecological Society http://dx.doi.org/10.13039/501100000409
    Description: https://doi.org/10.5281/zenodo.6884040
    Keywords: ddc:577.7 ; phytoplankton ; salinity change ; biotic interaction
    Language: English
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  • 40
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    Unknown
    John Wiley & Sons, Inc. | Hoboken, USA
    Publication Date: 2023-01-27
    Description: Since the early 2000s, proposals to deliberately modify the Earth's climate have gained political traction as a controversial last resort measure against dangerous global warming. The article provides a ‘longue durée’ picture of such climate engineering proposals. It traces their historical trajectory from the late 1950s to their most recent arrival on mainstream climate policy agendas. This perspective suggests that the history of climate engineering unfolds not only along historically specific modes of understanding climatic change. It also corresponds to changing alliances between climate science and the state. By bringing together historical scholarship with contributions from sociology and science policy studies, the article sheds new light on the rise of climate engineering proposals. It recontextualizes these proposals within the bigger history of the political cultivation of climate science. This perspective highlights how deeply entwined efforts to understand and efforts to govern climatic change have always been. This article is categorized under: Climate, History, Society, Culture 〉 Ideas and Knowledge The Social Status of Climate Change Knowledge 〉 Sociology/Anthropology of Climate Knowledge The Social Status of Climate Change Knowledge 〉 Knowledge and Practice
    Description: A traveler at the end of the world peeks beyond the limits of the Earth, reaching for the unknown skies. Wood Carving by Unknown Artist in Flammarion, C. (1888). L'atmosphère: Météorologie Populaire. Hachette.
    Description: German University of Administrative Sciences, Speyer (Germany)
    Keywords: ddc:304.25 ; climate change ; climate engineering ; geoengineering ; scientific expertise ; weather modification ; climate science
    Language: English
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  • 41
    Publication Date: 2023-01-27
    Description: River estuaries are characterized by mixing processes between freshwater discharge and marine water masses. Since the first are depleted in heavier stable isotopes compared with the marine realm, estuaries often show a linear correlation between salinity and water stable isotopes (δ18O and δ2H values). In this study, we evaluated spatial and seasonal isotope dynamics along three estuarine lagoon transects, located at the northern German Baltic Sea coast. The data show strong seasonality of isotope values, even at locations located furthest from the river mouths. They further reveal a positive and linear salinity‐isotope correlation in spring, but ‐in two of the three studied transects‐ hyperbolic and partially reverse correlations in summers. We conclude that additional hydrological processes partially overprint the two‐phase mixing correlation during summers: aside from the isotope seasonality of the riverine inflows, the shallow inner lagoons in the studied estuaries are influenced by evaporation processes. In contrast the estuarine outflow regions are under impact of significant salinity and isotope fluctuations of the Baltic Sea. Deciphering those processes is crucial for the understanding of water isotope and salinity dynamics. This is also of relevance in context of ecological studies, for example, when interpreting oxygen and hydrogen isotope data in aquatic organisms that depend on ambient estuarine waters.
    Description: Spatial and seasonal water isotope dynamics were evaluated along three estuarine lagoon transects at the German Baltic Sea coast. Data reveal a positive and linear salinity‐isotope correlation in spring, but partially reverse correlations in summers. The results show that evaporation processes in the shallow inner lagoons and varying Baltic Sea influence in the outer estuary regions are able to overprint the two‐phase mixing correlation between riverine and marine water masses.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.1594/PANGAEA.937990
    Keywords: ddc:551 ; δ2H ; δ18O ; Baltic Sea ; bodden ; Rügen ; salinity ; Schlei ; Zingst
    Language: English
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  • 42
    Publication Date: 2023-01-27
    Description: Dissolved organic matter (DOM) is the largest organic carbon reservoir in the ocean and an integral component of biogeochemical cycles. The role of free‐living microbes in DOM transformation has been studied thoroughly, whereas little attention has been directed towards the influence of benthic organisms. Sponges are efficient filter feeders and common inhabitants of many benthic communities circumglobally. Here, we investigated how two tropical coral reef sponges shape marine DOM. We compared bacterial abundance, inorganic and organic nutrients in off reef, sponge inhalant, and sponge exhalant water of Melophlus sarasinorum and Rhabdastrella globostellata. DOM and bacterial cells were taken up, and dissolved inorganic nitrogen was released by the two Indo‐Pacific sponges. Both sponge species utilized a common set of 142 of a total of 3040 compounds detected in DOM on a molecular formula level via ultrahigh‐resolution mass spectrometry. In addition, species‐specific uptake was observed, likely due to differences in their associated microbial communities. Overall, the sponges removed presumably semi‐labile and semi‐refractory compounds from the water column, thereby competing with pelagic bacteria. Within minutes, sponge holobionts altered the molecular composition of surface water DOM (inhalant) into a composition similar to deep‐sea DOM (exhalent). The apparent radiocarbon age of DOM increased consistently from off reef and inhalant to exhalant by about 900 14C years for M. sarasinorum. In the pelagic, similar transformations require decades to centuries. Our results stress the dependence of DOM lability definition on the respective environment and illustrate that sponges are hotspots of DOM transformation in the ocean.
    Description: Helmholtz Institute for Functional Marine Biodiversity at the University of Oldenburg
    Description: Ministry for Science and Culture of Lower Saxony http://dx.doi.org/10.13039/501100010570
    Description: Carl‐von‐Ossietzky University Oldenburg
    Description: Alfred‐Wegener‐Institute, Helmholtz‐Center for Polar and Marine Research
    Description: Volkswagen Foundation http://dx.doi.org/10.13039/501100001663
    Description: https://doi.org/10.5061/dryad.m0cfxpp6v
    Keywords: ddc:577.7 ; Indo-Pacific sponges ; dissolved organic matter ; biogeochemical cycles
    Language: English
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  • 43
    Publication Date: 2023-01-30
    Description: To summarize, we suggest a guideline for water quality modelling: 1. Spatial and temporal patterns of land use and land management are critical to adequately represent water quality in models. Remote sensing and land use models are very useful resources to be exploited. 2. The transfer of a model diagnostic analysis to water quality leads to a better understanding of how water quality variables are controlled by model structures and corresponding model parameters. 3. Assessing multiple model outputs regarding their temporal, spa- tial and process performance using observed time series, remotely sensed spatial patterns, knowledge about transport pathways and even soft data can significantly enhance model consistency. 4. Multi-metric calibration using performance metrics and signa- ture measures both for discharge and water quality, such as FDC and NDC, leads to more balanced model simulations that represent all magnitudes of discharge and water quality accurately. 5. Scenarios and storylines should be co-developed with stake- holders in the river basin to make them more realistic and increase the acceptance of model results. They should be realistic in space and time, and provide a mix of available management options. 6. The interpretation of BMPs can be supported by diagnostic tools to show the effectiveness of measures and their combinations while considering their costs and impacts on ecosystem services.
    Keywords: ddc:628.1 ; rural areas ; water quality modelling
    Language: English
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  • 44
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    Unknown
    John Wiley & Sons, Inc. | Hoboken, USA
    Publication Date: 2024-03-25
    Description: In 1989, Steve Rayner chided fellow anthropologists for “fiddling while the world warms.” This was the starting point of a decades‐long application to human‐made climate change of the cultural theory that he had developed with Mary Douglas and Michael Thompson. It culminated in a call to develop “clumsy” solutions for addressing the issue. Since then, the concept of clumsy solutions has been applied, praised, and criticised. To clarify its strengths and weaknesses, I first set out cultural theory and explain how the notion of clumsy solutions was derived from it. I then assess the extent to which this notion has increased our understanding of climate change governance. I do so by breaking up the application of this concept into seven predictions, concerning: (1) the major perspectives among stakeholders on how to resolve climate change; (2) the fate of the 1997 Kyoto Protocol; (3) the feasibility of international emissions trading; (4) the possibility of making renewable energy competitive; (5) the need for domestic governmental action to realize this possibility; (6) the effectiveness of a nonbinding global treaty to combat climate change; and (7) the need to explore adaptation, carbon capture, and geoengineering. I show that these predictions have stood the test of time. Finally, I discuss the roles that the concept of clumsy solutions can play in future climate change governance. This article is written in memory of Steve Rayner, one of the first social scientists to focus on climate change. This article is categorized under: Social Status of Climate Change Knowledge 〉 Sociology/Anthropology of Climate Knowledge Climate, History, Society, Culture 〉 Thought Leaders
    Keywords: ddc:363.7 ; clumsy solutions ; energy transition ; Steve Rayner
    Language: English
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  • 45
    Publication Date: 2024-02-05
    Description: Climate warming might modify infection outcomes and it has been proposed that temperature increase will result in a “sicker world.” We tested this hypothesis by comparing the prevalence of infection in a common freshwater host–parasite system (crustacean Daphnia infected with the ichthyosporean pathogen Caullerya mesnili) between five artificially heated lakes and four nearby non‐heated control lakes. The heated lakes, which receive warm water from two power plants, have experienced an elevation in water temperature of ca. 3–4°C for the last 60 yr. Analyses of 5 yr of field data revealed that Daphnia communities from heated lakes had lower parasite prevalence than communities from control sites. To disentangle a possible direct detrimental effect of elevated temperature on the parasite from differences in baseline levels of host resistance, we compared infection susceptibility between Daphnia clones isolated from heated and control lakes, under laboratory conditions at two different temperatures. Daphnia from heated lakes were less susceptible to infection than clones from control lakes, while experimental temperature did not affect infection outcome. The data did not confirm the “warmer hence sicker world” scenario. Instead, it seems that indirect effects of temperature elevation (via shifts in lake hydrology) may restrict its spread into heated lakes. Then, local adaptation to the host from control lakes further inhibits re‐establishment of the parasite from control to heated lakes. Our results underline the context‐dependency of the impact of temperature increase on host–parasite interactions.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Deutscher Akademischer Austauschdienst http://dx.doi.org/10.13039/501100001655
    Description: Fundacja Uniwersytetu im. Adama Mickiewicza http://dx.doi.org/10.13039/100016906
    Description: Ministerstwo Nauki i Szkolnictwa Wyższego http://dx.doi.org/10.13039/501100004569
    Description: Narodowe Centrum Nauki http://dx.doi.org/10.13039/501100004281
    Keywords: ddc:577.6 ; climate warming ; Poland ; heated lakes ; non-heated lakes ; Daphnia communities ; host–parasite interactions
    Language: English
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  • 46
    Publication Date: 2022-04-04
    Description: Harmful algal blooms (HABs) are globally increasing in number and spatial extent. However, their propagation dynamics along environmental gradients and the associated interplay of abiotic factors and biotic interactions are still poorly understood. In this study, a nutrient gradient was established in a linear meta‐ecosystem setup of five interconnected flasks containing an artificially assembled phytoplankton community. The harmful dinoflagellate Alexandrium catenella was introduced into different positions along the nutrient gradient to investigate dispersal and spatial community dynamics. Overall, total algal biovolume increased, while community evenness decreased with increasing nutrient concentrations along the gradient. Alexandrium was able to disperse through all flasks. On the regional scale, diatoms dominated the community, whereas on the local scale the dinoflagellate showed higher contributions at low nutrient concentrations and dominated the community at the lowest nutrient concentration, but only when initiated into this flask. A control treatment without dispersal revealed an even stronger dominance of Alexandrium at the lowest nutrient concentration, indicating that dispersal and the associated nutrient exchange may weaken dinoflagellate dominance under low nutrient conditions. This study presents a first approach to experimentally investigate spatial dynamics and ecological interactions of a harmful dinoflagellate along an environmental gradient in a meta‐ecosystem setup, which has the potential to substantially enhance our understanding of the relevance of dispersal for HAB formation and propagation in combination with local environmental factors.
    Description: Volkswagen Foundation http://dx.doi.org/10.13039/501100001663
    Keywords: ddc:579 ; ddc:550.724
    Language: English
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  • 47
    Publication Date: 2022-04-04
    Description: Microbial organic matter decomposition is a critical ecosystem function, which can be negatively affected by chemicals. Although the majority of organic matter is stored in sediments, the impact of chemicals has exclusively been studied in benthic systems. To address this knowledge gap, we assessed the impact of a fungicide mixture at three concentrations on the decomposition of black alder leaves in the benthic and hyporheic zone. We targeted two sediment treatments characterized by fine and coarse grain sizes (1–2 vs. 2–4 mm). Besides microbial communities' functioning (i.e., decomposition), we determined their structure through microbial biomass estimates and community composition. In absence of fungicides, leaf decomposition, microbial biomass estimates and fungal sporulation were lower in the hyporheic zone, while the importance of bacteria was elevated. Leaf decomposition was reduced (40%) under fungicide exposure in fine sediment with an effect size more than twice as high as in the benthic zone (15%). These differences are likely triggered by the lower hydraulic conductivity in the hyporheic zone influencing microbial dispersal as well as oxygen and nutrient fluxes. Since insights from the benthic zone are not easily transferable, these results indicate that the hyporheic zone requires a higher recognition with regard to ecotoxicological effects on organic matter decomposition.
    Description: German Research Foundation, Project AQUA‐REG http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:550.724 ; ddc:579
    Language: English
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  • 48
    Publication Date: 2022-04-04
    Description: Nutrients limiting phytoplankton growth in the ocean are a critical control on ocean productivity and can underpin predicted responses to climate change. The extensive western subtropical North Pacific is assumed to be under strong nitrogen limitation, but this is not well supported by experimental evidence. Here, we report the results of 14 factorial nitrogen–phosphorus–iron addition experiments through the Philippine Sea, which demonstrate a gradient from nitrogen limitation in the north to nitrogen–iron co‐limitation in the south. While nitrogen limited sites responded weakly to nutrient supply, co‐limited sites bloomed with up to ~60‐fold increases in chlorophyll a biomass that was dominated by initially undetectable diatoms. The transition in limiting nutrients and phytoplankton growth capacity was driven by a gradient in deep water nutrient supply, which was undetectable in surface concentration fields. We hypothesize that this large‐scale phytoplankton response gradient is both climate sensitive and potentially important for regulating the distribution of predatory fish.
    Description: National Natural Science Foundation of China http://dx.doi.org/10.13039/501100001809
    Keywords: ddc:577.7 ; ddc:550.724
    Language: English
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  • 49
    Publication Date: 2022-04-04
    Description: In 1883, Theodor Wilhelm Engelmann, a German scientist, wrote his essay “color and assimilation” (Ger.: “Farbe und Assimilation”) describing the state of the art in photosynthesis research, his recent findings, and further assumptions based upon his presented results. Nearly 140 years later, many of his assumptions were proven correct. By his still well‐known bacteria experiments using aerotactic, heterotrophic bacteria, he identified the chloroplasts as the location in which photosynthesis and oxygen production takes place. Furthermore, by evaluating the effects of different light spectra, he constructed the first action spectra that demonstrated the implication of the “green gap” of chlorophylls. He further posited that accessory photosynthetic pigments existed to extend the absorption range of chlorophyll. Although infrequently cited, his work was foundational for current ecological research of the vertical appearance of algae species within the underwater gradient in light spectrum due to specific harvesting of different light spectra, hence complementary chromatic adaptation of communities. This short retrospective highlights this piece of literature that represents an early step toward our current understanding of ecological competition for light spectra.
    Keywords: ddc:572.46 ; ddc:570.9
    Language: English
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  • 50
    Publication Date: 2022-04-07
    Description: Inland waters receive and process large amounts of colored organic matter from the terrestrial surroundings. These inputs dramatically affect the chemical, physical, and biological properties of water bodies, as well as their roles as global carbon sinks and sources. However, manipulative studies, especially at ecosystem scale, require large amounts of dissolved organic matter with optical and chemical properties resembling indigenous organic matter. Here, we compared the impacts of two leonardite products (HuminFeed and SuperHume) and a freshly derived reverse osmosis concentrate of organic matter in a set of comprehensive mesocosm‐ and laboratory‐scale experiments and analyses. The chemical properties of the reverse osmosis concentrate and the leonardite products were very different, with leonardite products being low and the reverse osmosis concentrate being high in carboxylic functional groups. Light had a strong impact on the properties of leonardite products, including loss of color and increased particle formation. HuminFeed presented a substantial impact on microbial communities under light conditions, where bacterial production was stimulated and community composition modified, while in dark potential inhibition of bacterial processes was detected. While none of the browning agents inhibited the growth of the tested phytoplankton Gonyostomum semen, HuminFeed had detrimental effects on zooplankton abundance and Daphnia reproduction. We conclude that the effects of browning agents extracted from leonardite, particularly HuminFeed, are in sharp contrast to those originating from terrestrially derived dissolved organic matter. Hence, they should be used with great caution in experimental studies on the consequences of terrestrial carbon for aquatic systems.
    Description: Marie Curie International Outgoing Fellowship
    Description: Swedish Research Council Formas http://dx.doi.org/10.13039/501100001862
    Description: Knut and Alice Wallenberg Foundation http://dx.doi.org/10.13039/501100004063
    Keywords: ddc:551.48 ; ddc:550.724
    Language: English
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  • 51
    Publication Date: 2022-04-01
    Description: The interaction between the land surface and the atmosphere is a crucial driver of atmospheric processes. Soil moisture and precipitation are key components in this feedback. Both variables are intertwined in a cycle, that is, the soil moisture – precipitation feedback for which involved processes and interactions are still discussed. In this study the soil moisture – precipitation feedback is compared for the sempiternal humid Ammer catchment in Southern Germany and for the semiarid to subhumid Sissili catchment in West Africa during the warm season, using precipitation datasets from the Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS), from the German Weather Service (REGNIE) and simulation datasets from the Weather Research and Forecasting (WRF) model and the hydrologically enhanced WRF‐Hydro model. WRF and WRF‐Hydro differ by their representation of terrestrial water flow. With this setup we want to investigate the strength, sign and variables involved in the soil moisture – precipitation feedback for these two regions. The normalized model spread between the two simulation results shows linkages between precipitation variability and diagnostic variables surface fluxes, moisture flux convergence above the surface and convective available potential energy in both study regions. The soil moisture – precipitation feedback is evaluated with a classification of soil moisture spatial heterogeneity based on the strength of the soil moisture gradients. This allows us to assess the impact of soil moisture anomalies on surface fluxes, moisture flux convergence, convective available potential energy and precipitation. In both regions the amount of precipitation generally increases with soil moisture spatial heterogeneity. For the Ammer region the soil moisture – precipitation feedback has a weak negative sign with more rain near drier patches while it has a positive signal for the Sissili region with more rain over wetter patches. At least for the observed moderate soil moisture values and the spatial scale of the Ammer region, the spatial variability of soil moisture is more important for surface‐atmosphere interactions than the actual soil moisture content. Overall, we found that soil moisture heterogeneity can greatly affect the soil moisture – precipitation feedback.
    Description: WRF and WRF‐hydro model simulations are used to determine the sign and analyse the mechanisms of the soil moisture ‐ precipitation feedback for the sempiternal humid Ammer catchment in Southern Germany and for the semiarid to subhumid Sissili catchment in West Africa during the warm season. The generation of moist convection is favoured over surfaces with moderately high soil moisture gradients in the Ammer region, while for the Sissili region the location of precipitation tends to be related to areas with high soil moisture gradients. For the Ammer region the soil moisture – precipitation feedback has a weak negative sign with more rain near drier patches while it has a positive signal for the Sissili region with more rain over wetter patches.
    Description: Untersuchung des Klimas des südlichen Afrikas – ein Brückenschlag vom frühen Holozän bis heute
    Description: Transregional Collaborative Research Center
    Keywords: ddc:551.57 ; ddc:631.4
    Language: English
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  • 52
    Publication Date: 2022-04-01
    Description: Light is a fundamental resource for phytoplankton. To utilize the available light, most phytoplankton species possess pigments in taxon‐specific combinations and quantities, which in turn result in a specific use of certain wavelengths. This optimizes the light use efficiency, allows for a complementary use of light, and may be an additional driver for community structure. While the effects of light intensity on phytoplankton biomass production and community composition have been intensively studied, here we focused on the effects of specific light spectrum quality (thus light color) on a natural phytoplankton community. In a controlled mesocosm experiment we reduced the supplied wavelength range to its blue, green, or red part of the light spectrum and compared the responses of each treatment to a full spectrum control over 28 d. Highest community growth rates were observed under blue, lowest under red light. Light absorption by the communities showed adaptation toward the supplied wavelength range. Community composition was significantly affected by light quality treatments, driven by Bacillariophyta and Chlorophyta, whereas pigment composition was not. Furthermore, lower species richness but higher evenness occurred when communities were exposed to red light compared to the full spectrum. We expected the response of phytoplankton communities to changes in the light spectrum to be driven by a combination of species sorting and pigment acclimation; however, the effect of species sorting turned out to be stronger. Our study showed that, even if species might acclimate, changes in the available light spectrum affect primary production and phytoplankton community composition.
    Keywords: ddc:579
    Language: English
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  • 53
    Publication Date: 2022-04-05
    Description: Nitrate monitoring is commonly conducted with low‐spatial resolution, only at the outlet or at a small number of selected locations. As a result, the information about spatial variations in nitrate export and its drivers is scarce. In this study, we present results of high‐spatial resolution monitoring conducted between 2012 and 2017 in 65 sub‐catchments in an Alpine mesoscale river catchment characterized by a land‐use gradient. We combined stable isotope techniques with Bayesian mixing models and geostatistical methods to investigate nitrate export and its main drivers, namely, microbial N turnover processes, land use and hydrological conditions. In the investigated sub‐catchments, mean values of NO3− concentrations and its isotope signatures (δ15NNO3 and δ18ONO3) varied from 2.6 to 26.7 mg L−1, from −1.3‰ to 13.1‰, and from −0.4‰ to 10.1‰, respectively. In this study, land use was an important driver for nitrate export. Very strong and strong positive correlations were found between percentages of agricultural land cover and δ15NNO3, and NO3− concentration, respectively. Mean proportional contributions of NO3− sources varied spatially and seasonally, and followed land‐use patterns. The mean contribution of manure and sewage was much higher in the catchments characterized by a high percentage of agricultural and urban land cover comparing to forested sub‐catchments. Specific NO3− loads were strongly correlated with specific discharge and moderately correlated with NO3− concentrations. The nitrate isotope and concentration analysis results suggest that nitrate from external sources is stored and accumulated in soil storage pools. Nitrification of reduced nitrogen species in those pools plays the most important role for the N‐dynamics in the Erlauf river catchment. Consequently, nitrification of reduced N sources was the main nitrate source except for a number of sub‐catchments dominated by agricultural land use. In the Erlauf catchment, denitrification plays only a minor role in controlling NO3− export on a regional scale.
    Description: We integrated results of the BMM with informative priors and top‐kriging. Reduced N stored in soil is an important source for stream N in a mesoscale catchment. Manure and sewage is the main NO3− source in agricultural sub‐catchments. Denitrification played only a minor role in controlling regional scale NO3− export.
    Keywords: ddc:551.48
    Language: English
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  • 54
    Publication Date: 2022-03-30
    Description: Complex networks of both natural and engineered flow paths control the hydrology of streams in major cities through spatio‐temporal variations in connection and disconnection of diverse water sources. We used spatially extensive and temporally intensive sampling of water stable isotopes to disentangle the hydrological sources of the heavily urbanized Panke catchment (~220 km2) in the north of Berlin, Germany. The isotopic data enabled us to partition stream water sources across the catchment using a Bayesian mixing analysis. The upper part of the catchment streamflow is dominated by groundwater (~75%) from gravel aquifers. In dry summer periods, streamflow becomes intermittent in the upper catchment, possibly as a result of local groundwater abstractions. Storm drainage dominates the responses to precipitation events. Although such events can dramatically change the isotopic composition of the upper stream network, storm drainage only accounts for 10%–15% of annual streamflow. Moving downstream, subtle changes in sources and isotope signatures occur as catchment characteristics vary and the stream is affected by different tributaries. However, effluents from a wastewater treatment plant (WWTP), serving 700,000 people, dominate stream flow in the lower catchment (~90% of annual runoff) where urbanization effects are more dramatic. The associated increase in sealed surfaces downstream also reduces the relative contribution of groundwater to streamflow. The volume and isotopic composition of storm runoff is again dominated by urban drainage, though in the lower catchment, still only about 10% of annual runoff comes from storm drains. The study shows the potential of stable water isotopes as inexpensive tracers in urban catchments that can provide a more integrated understanding of the complex hydrology of major cities. This offers an important evidence base for guiding the plans to develop and re‐develop urban catchments to protect, restore, and enhance their ecological and amenity value.
    Description: Intermittent urban stream. Groundwater and waste water dominance. High temporal and spatial stable isotope dataset. End member mixing analysis. Water import.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Einstein Stiftung Berlin http://dx.doi.org/10.13039/501100006188
    Description: Leverhulme Trust http://dx.doi.org/10.13039/501100000275
    Keywords: ddc:551.48
    Language: English
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  • 55
    Publication Date: 2022-03-30
    Description: Fjords are recognized as hotspots of organic carbon (OC) burial in the coastal ocean. In fjords with glaciated catchments, glacier discharge carries large amounts of suspended matter. This sedimentary load includes OC from bedrock and terrigenous sources (modern vegetation, peat, soil deposits), which is either buried in the fjord or remineralized during export, acting as a potential source of CO2 to the atmosphere. In sub‐Antarctic South Georgia, fjord‐terminating glaciers have been retreating during the past decades, likely as a response to changing climate conditions. We determine sources of OC in surface sediments of Cumberland Bay, South Georgia, using lipid biomarkers and the bulk 14C isotopic composition, and quantify OC burial at present and for the time period of documented glacier retreat (between 1958 and 2017). Petrogenic OC is the dominant type of OC in proximity to the present‐day calving fronts (60.4 ± 1.4% to 73.8 ± 2.6%) and decreases to 14.0 ± 2.7% outside the fjord, indicating that petrogenic OC is effectively buried in the fjord. Beside of marine OC, terrigenous OC comprises 2.7 ± 0.5% to 7.9 ± 5.9% and is mostly derived from modern plants and Holocene peat and soil deposits that are eroded along the flanks of the fjord, rather than released by the retreating fjord glaciers. We estimate that the retreat of tidewater glaciers between 1958 and 2017 led to an increase in petrogenic carbon accumulation of 22% in Cumberland West Bay and 6.5% in Cumberland East Bay, suggesting that successive glacier retreat does not only release petrogenic OC into the fjord, but also increases the capacity of OC burial.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:552 ; ddc:551.9
    Language: English
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  • 56
    Publication Date: 2022-03-30
    Description: Cell size is a master trait in the functional ecology of phytoplankton correlating with numerous morphological, physiological, and life‐cycle characteristics of species that constrain their nutrient use, growth, and edibility. In contrast to well‐known spatial patterns in cell size at macroecological scales or temporal changes in experimental contexts, few data sets allow testing temporal changes in cell sizes within ecosystems. To analyze the temporal changes of intraspecific and community‐wide cell size, we use the phytoplankton data derived from the Lower Saxony Wadden Sea monitoring program, which comprises sample‐ and species‐specific measurements of cell volume from 1710 samples collected over 14 yr. We find significant reductions in both the cell volume of most species and the weighted mean cell size of communities. Mainly diatoms showed this decline, whereas the size of dinoflagellates seemed to be less responsive. The magnitude of the trend indicates that cell volumes are about 30% smaller now than a decade ago. This interannual trend is overlayed by seasonal cycles with smaller cells typically observed in summer. In the subset of samples including environmental conditions, small community cell size was strongly related to high temperatures and low total phosphorus concentration. We conclude that cell size captures ongoing changes in phytoplankton communities beyond the changes in species composition. In addition, based on the changes in species biovolumes revealed by our analysis, we warn that using standard cell size values in phytoplankton assessment will not only miss temporal changes in size, but also lead to systematic errors in biomass estimates over time.
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Interreg V A program Deutschland‐Nederland of the European Union
    Description: Niedersächsisches Ministerium für Wissenschaft und Kultur http://dx.doi.org/10.13039/501100010570
    Description: https://doi.org/10.5281/zenodo.5799263
    Keywords: ddc:579.8 ; ddc:577.2
    Language: English
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  • 57
    Publication Date: 2022-03-24
    Description: The regional terrestrial water cycle is strongly altered by human activities. Among them, reservoir regulation is a way to spatially and temporally allocate water resources in a basin for multi‐purposes. However, it is still not sufficiently understood how reservoir regulation modifies the regional terrestrial‐ and subsequently, the atmospheric water cycle. To address this question, the representation of reservoir regulation into the terrestrial component of fully coupled regional Earth system models is required. In this study, an existing process‐based reservoir network module is implemented into NOAH‐HMS, that is, the terrestrial component of an atmospheric–hydrologic modelling system, namely, the WRF‐HMS. It allows to quantitatively differentiate role of reservoir regulation and of groundwater feedback in a simulated ground‐soil‐vegetation continuum. Our study focuses on the Poyang Lake basin, where the largest freshwater lake of China and reservoirs of different sizes are located. As compared to streamflow observations, the newly extended NOAH‐HMS slightly improves the streamflow and streamflow duration curves simulation for the Poyang Lake basin for the period 1979–1986. The inclusion of reservoir regulation leads to major changes in the simulated groundwater recharges and evaporation from reservoirs at local scale, but has minor effects on the simulated soil moisture and surface runoff at basin scale. The performed groundwater feedback sensitivity analysis shows that the strength of the groundwater feedback is not altered by the consideration of reservoir regulation. Furthermore, both reservoir regulation and groundwater feedback modify the partitioning of the simulated evapotranspiration, thus affecting the atmospheric water cycle in the Poyang Lake region. This finding motivates future research with our extended fully coupled atmospheric–hydrologic modelling system by the community.
    Description: An existing process‐based reservoir network module is implemented into the terrestrial component NOAH‐HMS of the atmospheric–hydrologic modelling system WRF‐HMS. The inclusion of reservoir regulation leads to major changes in the simulated groundwater recharges and evaporation from reservoirs at local scale, but does not alter the strength of the groundwater feedback. Reservoir regulation and groundwater feedback play different roles in modifying the regional terrestrial water cycle for the Poyang Lake basin, particularly with respect to the partitioning of the simulated evapotranspiration.
    Description: German Federal Ministry of Science and Education
    Description: German Research Foundation http://dx.doi.org/10.13039/501100001659
    Description: National Key R&D Program of China
    Description: National Natural Science Foundation of China http://dx.doi.org/10.13039/501100001809
    Keywords: ddc:551.49
    Language: English
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  • 58
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    John Wiley & Sons, Inc. | Hoboken, USA
    Publication Date: 2022-08-05
    Description: The end of the polar night with the concurrent onset of photosynthetic biomass production ultimately leads to the spring bloom, which represents the most important event of primary production for the Arctic marine ecosystem. This dataset shows, for the first time, significant in situ biomass accumulation during the dark–light transition in the high Arctic, as well as the earliest recorded positive net primary production rates together with constant chlorophyll a‐normalized potential for primary production through winter and spring. The results indicate a high physiological capacity to perform photosynthesis upon re‐illumination, which is in the same range as that observed during the spring bloom. Put in context with other data, the results of this study indicate that also active cells originating from the low winter standing stock in the water column, rather than solely resting stages from the sediment, can seed early spring bloom assemblages.
    Keywords: ddc:579.8
    Language: English
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  • 59
    Publication Date: 2022-08-09
    Description: Extreme wind storms can strongly influence short‐term variation in lake ecosystem functioning. Climate change is affecting storms by altering their frequency, duration, and intensity, which may have consequences for lake ecosystem resistance and resilience. However, catchment and lake processes are simultaneously affecting antecedent lake conditions which may shape the resistance and resilience landscape prior to storm exposure. To determine whether storm characteristics or antecedent lake conditions are more important for explaining variation in lake ecosystem resistance and resilience, we analyzed the effects of 25 extreme wind storms on various biological and physiochemical variables in a shallow lake. Using boosted regression trees to model observed variation in resistance and resilience, we found that antecedent lake conditions were more important (relative importance = 67%) than storm characteristics (relative importance = 33%) in explaining variation in lake ecosystem resistance and resilience. The most important antecedent lake conditions were turbidity, Schmidt stability, %O2 saturation, light conditions, and soluble reactive silica concentrations. We found that storm characteristics were all similar in their relative importance and results suggest that resistance and resilience decrease with increasing duration, mean precipitation, shear stress intensity, and time between storms. In addition, we found that antagonistic or opposing effects between the biological and physiochemical variables influence the overall resistance and resilience of the lake ecosystem under specific lake and storm conditions. The extent to which these results apply to the resistance and resilience of different lake ecosystems remains an important area for inquiry.
    Description: EU‐ITN MANTEL
    Description: Marie Sklodowska‐Curie
    Description: https://aslopubs.onlinelibrary.wiley.com/action/downloadSupplement?doi=10.1002%2Flno.11859&file=lno11859-sup-0001-Supinfo1.docx
    Description: https://aslopubs.onlinelibrary.wiley.com/action/downloadSupplement?doi=10.1002%2Flno.11859&file=lno11859-sup-0002-Supinfo2.docx
    Keywords: ddc:577.63 ; ddc:551.66
    Language: English
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