Reinhard Klenke

The Dark Side of Light: A Transdisciplinary Research Agenda for Light Pollution Policy

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 populations, and may reshape entire ecosystems. However, knowledge on the adverse effects of light pollution is vague. In response to climate change and energy shortages, many countries, regions, and communities are developing new lighting programs and concepts with a strong focus on energy efficiency and greenhouse gas emissions. Given the dramatic increase in artificial light at night (0 - 20% per year, depending on geographic region), we see an urgent need for light pollution policies that go beyond energy efficiency to include human well-being, the structure and functioning of ecosystems, and inter-related socioeconomic consequences. Such a policy shift will require a sound transdisciplinary understanding of the significance of the night, and its loss, for humans and the natural systems upon which we depend. Knowledge is also urgently needed on suitable lighting technologies and concepts which are ecologically, socially, and economically sustainable. Unless managing darkness becomes an integral part of future conservation and lighting policies, modern society may run into a global self-experiment with unpredictable outcomes.

Sleepless in town--drivers of the temporal shift in dawn song in urban European blackbirds.

Organisms living in urban environments are exposed to different environmental conditions compared to their rural conspecifics. Especially anthropogenic noise and artificial night light are closely linked to urbanization and pose new challenges to urban species. Songbirds are particularly affected by these factors, because they rely on the spread of acoustic information and adjust their behaviour to the rhythm of night and day, e.g. time their dawn song according to changing light intensities. Our aim was to clarify the specific contributions of artificial night light and traffic noise on the timing of dawn song of urban European Blackbirds (Turdus merula). We investigated the onset of blackbird dawn song along a steep urban gradient ranging from an urban forest to the city centre of Leipzig, Germany. This gradient of anthropogenic noise and artificial night light was reflected in the timing of dawn song. In the city centre, blackbirds started their dawn song up to 5 hours earlier compared to those in semi-natural habitats. We found traffic noise to be the driving factor of the shift of dawn song into true night, although it was not completely separable from the effects of ambient night light. We additionally included meteorological conditions into the analysis and found an effect on the song onset. Cloudy and cold weather delayed the onset, but cloud cover was assumed to reflect night light emissions, thus, amplified sky luminance and increased the effect of artificial night light. Beside these temporal effects, we also found differences in the spatial autocorrelation of dawn song onset showing a much higher variability in noisy city areas than in rural parks and forests. These findings indicate that urban hazards such as ambient noise and light pollution show a manifold interference with naturally evolved cycles and have significant effects on the activity patterns of urban blackbirds.

Seize the night: European Blackbirds (Turdus merula) extend their foraging activity under artificial illumination

AbstractIn the urbanized world, the diurnal cycle of light and darkness has lost its accuracy due to artificial light at night (LAN). Because light is one of the most important zeitgebers for the synchronization of the endogenous clock, this loss of the night has serious implications for health and activity patterns. Although it is a well-known phenomenon that LAN advances the onset of dawn song of passerines, little is known ABOUT whether birds extend their activity into the evening hours and THUS may benefit from exploiting the night light niche. By observing wild urban Blackbirds (Turdus merula) under different LAN intensities, we found birds exposed to high levels of LAN to forage longer in the evening than their conspecifics in the darker areas. This difference was most pronounced during the short days in March, but decreased steeply towards the summer solstice. However, body condition of the Blackbirds did not correlate with the exposure to LAN, indicating that urban birds extending their activity under LAN might not benefit from the prolonged foraging times. Our findings further indicate that male Blackbirds are more sensitive to LAN than females. This study reveals that LAN plays a considerable role in the activity times of urban Blackbirds but, regarding their body condition, other urban factors may be more important than the influence of LAN.ZusammenfassungNutze die Nacht: Amseln (Turdus merula) verlängern ihre Nahrungssuche unter künstlichem Nachlicht Der tägliche Wechsel zwischen Hell und Dunkel hat in der urbanisierten Welt durch das künstliche Nachtlicht seine Präzision verloren. Da Licht einer der wichtigsten Zeitgeber der inneren Uhr ist, hat dieser Verlust der Nacht weitreichende Auswirkungen auf Gesundheit und Aktivitätsmuster. Der unter künstlichem Licht früher einsetzende Morgengesang von Singvögeln ist ein gut untersuchtes Phänomen, jedoch ist nur wenig darüber bekannt, ob Vögel ihre Aktivität auch in die Abendstunden ausweiten und so von der Nachlicht-Nische profitieren können. Wir beobachteten frei lebende Amseln unter verschiedenen Lichtintensitäten und fanden, dass sie bei hohen nächtlichen Lichtintensitäten ihre Nahrungssuche stärker in die Abendstunden ausweiteten als Artgenossen im dunkleren Gebieten. Dieser Unterschied war während der kurzen Tage im März besonders ausgeprägt, nahm aber zum Sommer hin stark ab. Einen Zusammenhang zwischen der Körperkondition der Vögel und der nächtlichen Lichtintensität konnten wir nicht finden, was darauf hinweist, dass Vögel mit lichtbedingt längeren Aktivitätszeiten nicht von der verlängerten Nahrungssuche profitieren. Darüber hinaus scheinen Amselhähne sensibler als Amselhennen auf künstliches Nachtlicht zu reagieren. Diese Studie deutet darauf hin, dass künstliches Nachtlicht einen bedeutenden Einfluss auf die Aktivitätszeiten von städtischen Amseln hat, aber hinsichtlich der Körperkondition andere urbane Faktoren eine wichtigere Rolle als künstliches Nachtlicht haben.

Aquatic Insect Larvae as Indicators of Limiting Minimal Contents of Dissolved Oxygen - Part II

Abstract Minimal concentrations of oxygen are limiting factors for limnic biocenoses. It should therefore be possible to use biocenose structure to infer minimal oxygen concentrations that have occured, provided the tolerance of the organisms concerned is known. A simple apparatus used to measure LC50 of oxygen for aquatic insect larvae with tracheal gills is described. Lethal concentrations found in some Ephemeroptera differ between species. Usually, they are strongly temperature dependent. In the species so far studied, confidence intervals are very small and suggest that such insect larvae could be used as bioindicators of minimal oxygen concentrations (even of short term ones), especially in thermically stable waters.

Human - wildlife conflicts in Europe: Fisheries and fish-eating vertebrates as a model case

This book is about conflicts between different stakeholder groups triggered by protected species that compete with humans for natural resources. It presents key ecological features of typical conflict species and mitigation strategies including technical mitigation and the design of participatory decision strategies involving relevant stakeholders. The book provides a European perspective, but also develops a global framework for the development of action plans.

The use of coded wire tags to estimate cormorant predation on fish stocks in an estuary

One of the main obstacles to resolving the conflict between an increasing population of cormorants, Phalacrocorax carbo sinensis, and the fishing industry is the lack of documentation of the effect of the birds’ predation on fish stocks. Tagging and releasing fish with coded wire tags followed by intensive cormorant pellet sampling may be a viable method to measure the impact of cormorants on fish populations. To test this new method, we studied cormorant predation in a shallow estuary, where nearly 100 000 fish were tagged and more than 10 000 cormorant pellets were collected over a 3-year study period. A total of 112 tags were recovered from the collected pellets. Analyses of tag recovery data indicated considerable cormorant predation on tagged flounder, eel and salmon smolts, but the method did not deliver high-quality documentation, mainly because of limitations in pellet sampling. We conclude with recommendations to enhance the value of this method.

Confronting and coping with uncertainty in biodiversity research and praxis

There are many techniques to deal with uncertainty when modeling data. However, there are many forms of uncertainty that cannot be dealt with mathematically that have to be taken into account when designing a biodiversity monitoring system. Some of these can be minimized by careful planning and quality control, but others have to be investigated during monitoring, and the scale and methods adjusted when necessary to meet objectives. Sources of uncertainty include uncertainty about stakeholders, who will monitor, what to sample, where to sample, causal relationships, species identifications, detectability, distributions, relationships with remote sensing, biotic concordance, complementarity, validity of stratification, and data quality and management. Failure to take into account any of these sources of uncertainty about how the data will be used can make monitoring nothing more than monitoring for the sake of monitoring, and I make recommendations as to how to reduce uncertainties. Some form of standardization is necessary, despite the multiple sources of uncertainty, and experience from RAPELD and other monitoring schemes indicates that spatial standardization is viable and helps reduce many sources of uncertainty.

Non-Invasive Genetic Mark-Recapture as a Means to Study Population Sizes and Marking Behaviour of the Elusive Eurasian Otter (Lutra lutra)

Quantifying population status is a key objective in many ecological studies, but is often difficult to achieve for cryptic or elusive species. Here, non-invasive genetic capture-mark-recapture (CMR) methods have become a very important tool to estimate population parameters, such as population size and sex ratio. The Eurasian otter (Lutra lutra) is such an elusive species of management concern and is increasingly studied using faecal-based genetic sampling. For unbiased sex ratios or population size estimates, the marking behaviour of otters has to be taken into account. Using 2132 otter faeces of a wild otter population in Upper Lusatia (Saxony, Germany) collected over six years (2006–2012), we studied the marking behaviour and applied closed population CMR models accounting for genetic misidentification to estimate population sizes and sex ratios. We detected a sex difference in the marking behaviour of otters with jelly samples being more often defecated by males and placed actively exposed on frequently used marking sites. Since jelly samples are of higher DNA quality, it is important to not only concentrate on this kind of samples or marking sites and to invest in sufficiently high numbers of repetitions of non-jelly samples to ensure an unbiased sex ratio. Furthermore, otters seemed to increase marking intensity due to the handling of their spraints, hence accounting for this behavioural response could be important. We provided the first precise population size estimate with confidence intervals for Upper Lusatia (for 2012: N^ = 20 ± 2.1, 95% CI = 16–25) and showed that spraint densities are not a reliable index for abundances. We further demonstrated that when minks live in sympatry with otters and have comparably high densities, a non-negligible number of supposed otter samples are actually of mink origin. This could severely bias results of otter monitoring if samples are not genetically identified.

Seasonal and urban effects on the endocrinology of a wild passerine

Abstract In order to maximize their fitness, organisms in seasonal environments rely on external cues to optimally time their life‐history stages. One of the most important zeitgeber to time reproduction is the photoperiod, but further environmental cues are assessed to fine‐tune reproduction due to year‐to‐year variation in environmental conditions. However, in urbanized environments, the pervasive artificial light at night has altered the natural signal of light and darkness. Accordingly, artificial light at night was repeatedly shown to affect avian reproductive physiology and to advance seasonal reproduction in birds. However, these experiments were mainly conducted in the absence of further environmental cues to facilitate the investigation of the mechanisms which are still poorly understood. Here, we investigate whether the endocrine system of free‐ranging European blackbirds (Turdus merula) correlates with the amount of artificial light at night along a rural to urban gradient while the birds still encounter complementary environmental cues including seasonal variation in day length and temperature. Testosterone and estrone were assessed as metabolites in fecal samples and corticosterone in blood from mist‐netted blackbirds. We demonstrate that seasonal fluctuations in abiotic factors, individual conditions, but also light at night affect the reproductive and stress physiology of wild European blackbirds. Elevated artificial night light intensities were significantly positively correlated with corticosterone and negatively with female estrone levels. No effects of artificial light were found for testosterone levels. Our results suggest that female blackbirds in particular perceive even low levels of artificial light at night as a weak but chronic stressor that interacts with the hypothalamic‐pituitary‐gonadal axis and leads to a reduced secretion of reproductive hormones. These findings point out that the impacts of light pollution are diverse and we only slowly disentangle its multiple effects on physiology, ecology, and biodiversity.

Multicriterion trade‐offs and synergies for spatial conservation planning

Summary 1.Nature conservation policies need to deliver on multiple criteria, including genetic diversity, population viability and species richness as well as ecosystem services. The challenge of integrating these may be addressed by simulation modelling. 2.We used four models (MetaConnect, SPOMSIM, a community model and InVEST) to assess a variety of spatial habitat patterns with two levels of total habitat cover and realised at two spatial scales, exploring which landscape structures performed best according to five different conservation criteria assessed for four functional types of organisms (approximately representing trees, butterflies, small mammals and birds). 3.The results display both synergies and trade-offs: population size and pollination services generally benefitted more from fragmentation than did genetic heterozygosity, and species richness more than allelic richness, although the latter two varied considerably among the functional types. 4 No single landscape performed best across all conservation criteria, but averaging over criteria and functional types, overall performance improved with greater levels of habitat cover and intermediate fragmentation (or less fragmentation in cases with lower habitat cover). 5.Policy implications. Using four simulation models we show that different conservation objectives must be traded off in spatial conservation planning, and that considering only a single taxon or criterion may result in sub-optimal choices when planning reserve networks. Nevertheless, heterogeneous spatial patterns of habitat can provide reasonable compromises for multiple criteria. This article is protected by copyright. All rights reserved.