Klement Tockner's research while affiliated with Goethe-Universität Frankfurt am Main and other places

Publications (82)

Article
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The cover image is based on the Viewpoint A global agenda for advancing freshwater biodiversity research by Alain Maasri et al., https://doi.org/10.1111/ele.13931. Image Credit: Solvin Zankl. image
Book
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Rivers of Europe, Second Edition, presents the latest update on the only primary source of complete and comparative baseline data on the biological and hydrological characteristics of more than 180 of the highest profile rivers in Europe. With even more full-color photographs and maps, the book includes conservation information on current patterns...
Article
The fragmentation of free-flowing rivers (FFRs) through major infrastructure development remains a pivotal threat to global freshwater biodiversity. More than 3400 large hydropower dams (>1 MW) are either planned or under construction, posing threats to freshwater megafauna (i.e., freshwater animals that can reach 30 kg). Here, we investigate the g...
Article
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Flowing waters have a unique role in supporting global biodiversity, biogeochemical cycles and human societies1–5. Although the importance of permanent watercourses is well recognized, the prevalence, value and fate of non-perennial rivers and streams that periodically cease to flow tend to be overlooked, if not ignored6–8. This oversight contribut...
Preprint
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Freshwater biodiversity is declining dramatically, and the current biodiversity crisis requires defining bold goals and mobilizing substantial resources to meet the challenges. While the reasons are varied, both research and conservation of freshwater biodiversity lag far behind efforts in the terrestrial and marine realms. We identify fifteen pres...
Preprint
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Freshwater biodiversity is declining dramatically, and the current biodiversity crisis requires defining bold goals and mobilizing substantial resources to meet the challenges. While the reasons are varied, both research and conservation of freshwater biodiversity lag far behind efforts in the terrestrial and marine realms. We identify fifteen pres...
Preprint
The diversity of life sensu lato comprises both biological and cultural diversity, described as “biocultural diversity”. Similar to plant and animal species, cultures and languages are threatened by extinction, too. Since drylands are pivotal systems for nature and people alike, we use oases in the Sahara Desert as model systems for examining patte...
Article
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A recent global meta‐analysis reported a decrease in terrestrial but increase in freshwater insect abundance and biomass (van Klink et al., Science 368, p. 417). The authors suggested that water quality has been improving, thereby challenging recent reports documenting drastic global declines in freshwater biodiversity. We raise two major concerns...
Article
We call attention to the importance of protecting spring ecosystems, which are globally pivotal to the well-being of humanity and nature. These fragile, keystone ecosystems are rapidly disappearing because of unchecked appropriation of groundwater and site-specific habitat destruction. Springs harbor disproportionately high biodiversity due to micr...
Article
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Megafauna species are intrinsically vulnerable to human impact. Freshwater megafauna, i.e. freshwater animals ≥ 30 kg, including fishes, mammals, reptiles, and amphibians, are subject to intensive and increasing threats, with 34 species listed as Critically Endangered on the IUCN Red List. IUCN Red List assessments are an important basis for conser...
Article
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Although the invention and widespread use of artificial light is clearly one of the most important human technological advances, the transformation of nightscapes is increasingly recognized as having adverse effects. Night lighting may have serious physiological consequences for humans, ecological and evolutionary implications for animal and plant...
Article
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Viele meinen, wir leben in einer Wissensgesellschaft. Tatsächlich aber entstehen aus den vielen Daten und Informationen, die wir erheben, zu selten echtes Wissen und Verständnis. Ein Grund dafür ist unsere Orientierungslosigkeit in fast allen Disziplinen außer unserer eigenen. Ein möglicher Ausweg ist ein frei zugänglicher interaktiver Wissenschaft...
Article
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Interdisciplinary science is rapidly advancing to address complex human-environment interactions. River science aims to provide the methods and knowledge required to sustainably manage some of the planet’s most important and vulnerable ecosystems; and there is a clear need for river managers and scientists to be trained within an interdisciplinary...
Article
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Protected areas (PAs) are an essential tool for freshwater biodiversity conservation. Given past and expected future global increases in dams and impacts of dams on freshwater ecosystems, we document the number of dams existing or planned within PAs, their history, and the extent of PA downgrading, downsizing, and degazettement (PADDD) proximally c...
Article
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Concern for megafauna is increasing among scientists and non-scientists. Many studies have emphasized that megafauna play prominent ecological roles and provide important ecosystem services to humanity. But, what precisely are ‘megafauna’? Here, we critically assess the concept of megafauna and propose a goal-oriented framework for megafaunal resea...
Article
Intermittent streams are subject to high levels of environmental variation. However, little is known about how biota responds to river drying across the channel-to-upland habitat gradient. This is an important shortcoming because assumes that intermittent river habitats and metacommunities are static. Here we studied how river drying affects the sp...
Article
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Dam construction comes with severe social, economic and ecological impacts. From an ecological point of view, habitat types are altered and biodiversity is lost. Thus, to identify areas that deserve major attention for conservation, existing and planned locations for (hydropower) dams were overlapped, at global extent, with the contemporary distrib...
Article
Freshwater ecosystems are among the most diverse and dynamic ecosystems on Earth. At the same time, they are among the most threatened ecosystems but remain underrepresented in biodiversity research and conservation efforts. The rate of decline of vertebrate populations is much higher in freshwaters than in terrestrial or marine realms. Freshwater...
Article
Freshwaters are among the most diverse and dynamic ecosystems globally, while also being among the most threatened systems. Freshwater biological field stations (FW‐BFS) are key facilities for research, monitoring, and education. However, high quality data and information on the status and roles of FW‐BFS are lacking. Based on the results of a ques...
Article
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Freshwaters are among the most complex, dynamic, and diverse ecosystems globally. Despite their small share of the earth’s surface (less than 1%) they are home to over 10% of all known animal species. Biodiversity decrease in general and freshwater biodiversity decline in particular have recently received increasing attention, and various policy in...
Article
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Species distribution data are crucial for understanding biodiversity dynamics and the underlying drivers. For freshwaters, which cover only a small proportion of the world's surface, but host a large variety of species, knowledge on species occurrences is extremely important as they are among the most endangered ecosystems globally. However, a huge...
Article
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A key dimension of our current era is Big Data, the rapid rise in produced data and information; a key frustration is that we are nonetheless living in an age of ignorance, as the real knowledge and understanding of people does not seem to be substantially increasing. This development has critical consequences, for example it limits the ability to...
Article
Climate change and human pressures are changing the global distribution and the extent of intermittent rivers and ephemeral streams (IRES), which comprise half of the global river network area. IRES are characterized by periods of flow cessation, during which channel substrates accumulate and undergo physico‐chemical changes (preconditioning), and...
Article
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Climate change and human pressures are changing the global distribution and extent of intermittent rivers and ephemeral streams (IRES), which comprise half of the global river network area. IRES are characterized by periods of flow cessation, during which channel substrates accumulate and undergo physico‐chemical changes (preconditioning), and peri...
Article
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Globally, freshwater is unevenly distributed, both in space and time. Climate change, land use alteration, and increasing human exploitation will further increase the pressure on water as a resource for human welfare and on inland water ecosystems. Water transfer megaprojects (WTMP) are defined here as large-scale engineering interventions to diver...
Article
In the 12 years since Dudgeon et al. (2006) reviewed major pressures on freshwater ecosystems, the biodiversity crisis in the world's lakes, reservoirs, rivers, streams and wetlands has deepened. While lakes, reservoirs and rivers cover only 2.3% of the Earth's surface, these ecosystems host at least 9.5% of the Earth's described animal species. Fu...
Preprint
Globally, freshwater is unevenly distributed, both in space and time. Climate change, land use alteration, and increasing human exploitation will further increase the pressure on water as a resource for human welfare and on inland water ecosystems. Water transfer megaprojects (WTMP), i.e. large-scale engineering interventions to divert water within...
Article
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The rapid erosion of biodiversity is among the biggest challenges human society is facing. Concurrently, major efforts are in place to quantify changes in biodiversity, to understand the consequences for ecosystem functioning and human wellbeing, and to develop sustainable management strategies. Based on comprehensive bibliometric analyses covering...
Data
Comparison of search algorithm (solid line) and subsample data (dashed line, with confidence interval) for level (genetic, phylogenetic, species, ecosystem). (PDF)
Data
Comparison of automatic search (i.e. all publication titles and abstracts were automatically searched for search terms; Solid line) and subsample data (dashed line, with confidence interval) for research domain (terrestrial, freshwater, marine). (PDF)
Data
Comparison of search algorithm (solid line) and subsample data (dashed line, with confidence interval) for taxonomic group (plants and algae, vertebrates, invertebrates, bacteria, fungi, virus). (PDF)
Data
Categories of institutions of core scientists. (PDF)
Data
Cartograms showing ratios between biodiversity-related research effort and biodiversity quantities. In (A) the size of each country represents the number of amphibian species (based on AmphibiaWeb); the color represents the ratio between publication count and number of amphibians. In (B) the size of each country represents the number of bird specie...
Data
Gender distribution of core scientists in biodiversity research. (PDF)
Data
Correlation of number of ecoregions with number of amphibians and number of birds on country level (n = 201). (PDF)
Data
Search terms for automatic search through publications. (XLSX)
Data
Comparison research effort considering all affiliations and only unique affiliations of first authors. (PDF)
Data
Institutions of biodiversity core scientists. Institutions with <5 core scientists are summarized to “other institutions”. (PDF)
Data
Correlation of GDP, number of threatened species, number of ecoregions and percentage of protected area with publications related to countries of authors’ affiliation (A) and countries of study site (B) (n = 199). (PDF)
Article
Aim Freshwater megafauna remain underrepresented in research and conservation, despite a disproportionately high risk of extinction due to multiple human threats. Therefore, our aims are threefold; (i) identify global patterns of freshwater megafauna richness and endemism, (ii) assess the conservation status of freshwater megafauna and (iii) demons...
Article
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Freshwater biodiversity is highly threatened and is decreasing more rapidly than its terrestrial or marine counterparts; however, freshwaters receive less attention and conservation investment than other ecosystems do. The diverse group of freshwater megafauna, including iconic species such as sturgeons, river dolphins, and turtles, could, if promo...
Article
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Understanding complex, dynamic, and diverse ecosystems is essential for developing sound management and conservation strategies. Gravel-bed river floodplains are composed of an interlinked mosaic of aquatic and terrestrial habitats hosting a diverse, specialized, and endangered fauna. Therefore, they serve as excellent models to investigate the bio...
Article
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Despite exposed surface sediments of braided, gravel-bed rivers host a diverse and endangered arthropod fauna, the ecology of the unsaturated layers below the surface but above the groundwater is mostly unexplored. Even if only parts of this zone are accessible to arthropods, this could be the most extensive habitat along braided rivers with likely...
Article
1. There is a growing concern that artificial light might affect local insect populations and disrupt their dispersal across the landscape. In this study, we investigated experimentally the effect of artificial light on flying insects in the field, with an emphasis on aquatic insects. We asked whether lights prevented the ability of insects to disp...
Article
Artificial light at night is prevalent in human-dominated landscapes, and streams in these landscapes can be expected to be affected by artificial lights. We hypothesised that artificial light at night would reduce the activity of aquatic insects, resulting in reduced drift rates, lower fish growth rates and lower leaf litter decomposition rates.We...
Article
Quantifying spatial and temporal dynamics of organic matter (OM) is critical both for understanding ecosystem functioning and for predicting impacts of landscape change. To determine the influence of different habitats and coarse particulate OM (CPOM) types upon floodplain OM dynamics, we quantified aerial input, lateral surface transfer, and surfa...
Chapter
Menschen siedeln seit jeher bevorzugt in der Nähe von Gewässern. Künstliches Licht in der Nacht konzentriert sich daher besonders entlang der Ufer von Bächen, Flüssen, Kanälen, Seen und Meeresküsten. Zugleich ist die Übergangszone von Wasser und Land ein äußerst artenreicher Lebensraum, mit einer Vielzahl lichtsensitiver und gefährdeter aquatischer...
Article
Summary1. Vegetated islands within river corridors are pivotal landscape features and are among the first to disappear as a consequence of flow regulation and channelisation. However, how vegetated islands vary along human‐impacted rivers is poorly understood.2. We carried out a detailed analysis of the contemporary distribution, diversity and envi...
Article
River floodplains are heterogeneous landscapes composed of a mosaic of aquatic and terrestrial habitats. While flow has frequently been considered as a master variable that controls aquatic biodiversity and species behavior in river floodplains, little is known about thermal heterogeneity and its effect on aquatic biota in complex landscapes. Howev...
Conference Paper
Background/Question/Methods Most of the research on artificial light has focused on one group of organisms (such as sea turtles or insects), however, artificial light might also influence entire ecosystems and how they function. We aimed to test a series of hypotheses about how artificial light might change stream ecosystem processes. Specifically...
Conference Paper
Background/Question/Methods Artificial light at night is gaining more attention for its potential to alter ecosystems. However, there is a noticeable lack of research on artificial light and freshwater systems. This is despite freshwaters having high biodiversity and being disproportionally affected by species loss. In addition, most of the few ex...
Article
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Throughout the last centuries most large rivers have increasingly become humandominated ecosystems as a result of land reclamation, floodplain drainage, hydropower production, and channelization for navigation. Their domestication, i.e. their optimization for few ecosystem services, has fundamentally altered habitat conditions and led to the format...
Article
1. In their natural state, river floodplains are composed of a complex mosaic of contrasting aquatic and terrestrial habitats. These habitats are expected to differ widely in their properties and corresponding ecological processes, although empirical data on their capacity to produce, store and transform organic matter and nutrients are limited. 2....
Article
Full-text available
Although the invention and widespread use of artificial light is clearly one of the most important human technological advances, the transformation of nightscapes is increasingly recognized as having adverse effects. Night lighting may have serious physiological consequences for humans, ecological and evolutionary implications for animal and plant...
Article
Co-existence of species has been a central debate in ecology for decades but the mechanisms that allow co-existence are still heatedly disputed. The main paradigms have shifted among the importance of competition, predation and abiotic conditions as determinants of community structure. Differential habitat selection is considered to reduce competit...
Article
River floodplains are composed of a shifting mosaic of aquatic and terrestrial habitats. Each habitat type exhibits distinct environmental and ecological properties. Temperature is a key property driving ecological processes and controlling the composition and distribution of biota. However, given the size and complexity of floodplains, ground surv...
Article
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Body size at metamorphosis is a critical trait in the life history of amphibians. Despite the wide-spread use of amphibians as experimental model organisms, there is a limited understanding of how multiple abiotic and biotic factors affect the variation in metamorphic traits under natural conditions. The aim of our study was to quantify the effects...
Article
Differential habitat selection is a central component in the evolution of species, but it has been quantified rarely for sympatric species in relation to the multiple impacts of resources at the spatial scales at which animals operate. Our main goal was to quantify the selection of terrestrial summer habitats in a natural floodplain in Italy by two...
Article
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Understanding individual space use remains a major issue in ecology, and it is complicated by definitions of spatial scale and the interplay of multiple factors. We quantified the effect of habitat and biotic and individual factors on space use by amphibians (Bufo bufo spinosus [BB] and Bufo viridis [BV]) that were radio-tracked in their terrestria...
Article
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Fine particulate organic matter (FPOM) plays a critical role in structuring and sustaining stream food webs by providing an essential resource for various organisms. Our goal was to elucidate FPOM dynamics by determining chemical properties, microbial respiration, and in situ decomposition rates of different FPOM fractions in relation to the parent...
Article
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Riverine floodplains are a mosaic of aquatic, semi-aquatic and terrestrial habitats. While spatially distinct, these habitats are well connected by flows of carbon and nutrients, often in the form of leaf litter, and thus the ecological processes occurring in one habitat have ramifications for others. The aim of this study was to compare leaf decom...
Article
1. Elaborate restoration attempts are underway worldwide to return human-impacted rivers to more natural conditions. Assessing the outcome of river restoration projects is vital for adaptive management, evaluating project efficiency, optimising future programmes and gaining public acceptance. An important reason why assessment is often omitted is l...
Article
River ecosystems are increasingly viewed as dynamic riverscapes; their extent, composition, and configuration vary in response to the pulsing of discharge. Although compositional and configurational shifts in riverscapes are thought to control ecosystem processes and biodiversity, attempts to quantify riverscape dynamics of braided rivers are scarc...
Article
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Despite growing recognition of the importance of a natural flow regime in river-floodplain systems, researchers struggle to quantify ecosystem responses to altered hydrological regimes. How do frequency, timing, and duration of inundation affect fundamental ecosystem processes such as leaf litter decomposition? Along the semi-natural Tagliamento Ri...
Article
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Environmental heterogeneity is a key regulator of ecological processes. River- ine floodplains are particularly heterogeneous and dynamic systems and loss of their natural environmental heterogeneity and dynamism as a consequence of human impacts constitutes their most serious threat. On river floodplains, flow and flood pulses create a shifting mo...
Article
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Investigations of European floodplain rivers demonstrate how landscape ecology can provide an effective framework to integrate pattern and process in river corridors, to examine environmental dynamics and interactive pathways between landscape elements, and to develop viable strategies for river conservation. The highly complex and dynamic nature o...
Article
Daily and seasonal water temperature patterns were investigated at 22 habitats in five geomorphic reaches along an Alpine-Mediterranean river. Study reaches spanned 2nd- to 7th-order river segments. Habitats included headwater streams, main and secondary channels, backwaters, and isolated pools. Multiple linear regression analyses extracted elevati...
Article
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Spatio-temporal heterogeneity in physico-chemical conditions associated with the annual expansion/contraction cycle in a complex glacial flood plain of the Swiss Alps was investigated employing a landscape approach. The diverse and dynamic aquatic habitats of the flood plain were visualized as an aquatic mosaic or riverscape. Based on samples colle...
Article
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The influence of river-catchment hydrological interactions on discharge patterns, lotic ecosystem size, and surface water chemistry were investigated in a glacial floodplain of the Swiss Alps (Val Roseg). Discharge, the extent and form of the stream network, specific conductance, and concentrations of major ions were measured periodically at multip...

Citations

... The increasing demand for freshwater resources to sustain human needs has put a strain on the global river systems resulting in their fragmentation and the subsequent decline of biodiversity (Grill et al., 2019;He et al., 2021). Fish metrics such as abundance, assemblage composition, assemblage richness and species spatial distributions have been used to establish a more accurate measure of ecological integrity in freshwater ecosystems (Karr, 1981;Daga et al., 2012). ...
... The growing body of river plastic evidence (Blettle et al., 2018;Lebreton et al., 2022;van Emmerik et al., 2020) repors highly polluted streams carrying up to several thousand tons per year (Meijer et al., 2021;González-Fernández et al., 2021). However, seasonal flux fluctuations as well as river network transport connectivity for floating plastic debris are still poorly understood Harris et al., 2021;van