@techreport{KybaArroyoDegenetal.2024, author = {Kyba, Christopher C.M. and Arroyo, Hector Linares and Degen, Tobias and Abascal, Angela and Simoneau, Alexandre and Kuffer, Monika and H{\"o}lker, Franz and Aub{\´e}, Martin and Walczak, Ken and Espey, Brian R. and de Miguel, Alejandro S{\´a}nchez and Jechow, Andreas and Gyuk, Geza}, title = {Night Watch Mission Description Document}, publisher = {GFZ German Research Centre for Geosciences}, address = {Potsdam}, doi = {10.48440/gfz.b103-24052}, pages = {1 -- 156}, year = {2024}, abstract = {This is the Mission Description Document (MDD) for a future Earth observation satellite mission addressing visible band observations of nighttime lights. The mission driving science applications are for the remote sensing of electricity, energy, and ecological impacts via the observation of artificial light. The MDD covers the mission requirements justification from the high-level scientific objectives and societal benefits to measurement requirements at product level 1b, i.e. radiances at the top of the atmosphere. In providing justification for the individual requirements and their traceability to scientific objectives and societal challenges, we address Scientific Readiness Levels 1 to 3. The MDD is the outcome of the European Space Agency New Earth Observation Mission Ideas project "Night Watch". The Task Reports (TR) from the project are appended to the MDD, and are authored by the same group as the MDD itself.}, language = {en} } @article{SchumannStoilovaBortolettoetal.2025, author = {Schumann, Sophia and Stoilova, Velizara and Bortoletto, Enrico and Piva, Elisabetta and Pacchini, Sara and Mozzi, Gloria and Jechow, Andreas and Marion, Andrea and Bertotto, Daniela and Erlandson, Ann and H{\"o}lker, Franz and Greenberg, Larry and Santovito, Gianfranco}, title = {Impact of artificial light at night (ALAN) on cardiac function and acute oxidative stress physiology in migratory brown trout smolts}, series = {Environmental Pollution}, journal = {Environmental Pollution}, number = {381}, publisher = {Elsevier}, doi = {10.1016/j.envpol.2025.126593}, pages = {1 -- 9}, year = {2025}, abstract = {Light pollution poses significant ecological challenges for nocturnal animals reliant on natural light for migration, orientation, and circadian rhythms. The physiological effects of abrupt exposure to artificial light at night (ALAN) on migratory fish, such as the light experienced passing near illuminated infrastructures, remain poorly understood. This study investigates the physiological responses of brown trout (Salmo trutta) smolts to low-intensity (0.02 lx) and short-term (30 s) ALAN, simulating nocturnal migration light conditions near illuminated bridges. To evaluate the influence of social dynamics, trout were tested individually (solitary) or in groups of six. Using continuous cardiac monitoring with data storage tags, alongside analyses of oxidative stress markers and adenylate kinase (AK) activity in the heart, we identified distinct patterns of physiological responses. Solitary fish exhibited significant heart rate variability (HRV) increases following repeated ALAN exposure, suggesting impaired physiological regulation under repeated ALAN exposure. In contrast, trout in groups displayed consistently lower HRV over the entire 90-min experiment, implying that social dynamics likely influenced a sustained oxidative stress response, corroborated by increased AK activity. Oxidative stress markers further reflected social effects, with significant upregulation of key antioxidant enzymes (sod1, sod2, gpx1, gpx4) and elevated lipid peroxidation, identifying lipids as primary oxidative targets. The observed divergence between superoxide dismutase (SOD) activity and sod gene expression suggests adaptive post-transcriptional regulation to maintain redox balance under combined environmental and social stress. These findings reveal that social dynamics under ALAN can amplify physiological stress, potentially affecting migratory outcomes.}, language = {en} } @article{KalinkatJechowSchroeretal.2025, author = {Kalinkat, Gregor and Jechow, Andreas and Schroer, Sibylle and H{\"o}lker, Franz}, title = {Nocturnal pandas: conservation umbrellas protecting nocturnal biodiversity}, series = {Trends in Ecology \& Evolution}, volume = {40}, journal = {Trends in Ecology \& Evolution}, number = {8}, publisher = {Elsevier}, doi = {10.1016/j.tree.2025.05.006}, pages = {736 -- 739}, year = {2025}, abstract = {Light pollution is an emerging ecological threat. To mitigate its negative consequences, creative inter- and transdisciplinary solutions and societal interactions are needed. To this end, we introduce nocturnal umbrella species representative of light-sensitive biodiversity whose protection will safeguard vital ecosystem services and a wide range of co-occurring species.}, language = {en} } @article{JechowBumbergerPalmetal.2024, author = {Jechow, Andreas and Bumberger, Jan and Palm, Bert and Remmler, Paul and Schreck, G{\"u}nter and Ogashawara, Igor and Kiel, Christine and Kohnert, Katrin and Grossart, Hans-Peter and Singer, Gabirel A. and Nejstgaard, Jens C. and Wollrab, Sabine and Berger, Stella A. and H{\"o}lker, Franz}, title = {Characterizing and Implementing the Hamamatsu C12880MA Mini-Spectrometer for Near-Surface Reflectance Measurements of Inland Waters}, series = {Sensors}, volume = {24}, journal = {Sensors}, number = {19}, publisher = {MDPI}, doi = {10.3390/s24196445}, pages = {1 -- 14}, year = {2024}, abstract = {In recent decades, inland water remote sensing has seen growing interest and very strong development. This includes improved spatial resolution, increased revisiting times, advanced multispectral sensors and recently even hyperspectral sensors. However, inland waters are more challenging than oceanic waters due to their higher complexity of optically active constituents and stronger adjacency effects due to their small size and nearby vegetation and built structures. Thus, bio-optical modeling of inland waters requires higher ground-truthing efforts. Large-scale ground-based sensor networks that are robust, self-sufficient, non-maintenance-intensive and low-cost could assist this otherwise labor-intensive task. Furthermore, most existing sensor systems are rather expensive, precluding their employability. Recently, low-cost mini-spectrometers have become widely available, which could potentially solve this issue. In this study, we analyze the characteristics of such a mini-spectrometer, the Hamamatsu C12880MA, and test it regarding its application in measuring water-leaving radiance near the surface. Overall, the measurements performed in the laboratory and in the field show that the system is very suitable for the targeted application.}, language = {en} } @article{OgashawaraWollrabBergeretal.2024, author = {Ogashawara, Igor and Wollrab, Sabine and Berger, Stella A. and Kiel, Christine and Jechow, Andreas and Guislain, Alexis L. N. and Gege, Peter and Ruhtz, Thomas and Hieronymi, Martin and Schneider, Thomas and Lischeid, Gunnar and Singer, Gabriel A. and H{\"o}lker, Franz and Grossart, Hans-Peter and Nejstgaard, Jens Christian}, title = {Unleashing the power of remote sensing data in aquatic research: Guidelines for optimal utilization}, series = {Limnology and Oceanography Letters}, journal = {Limnology and Oceanography Letters}, publisher = {Wiley}, doi = {10.1002/lol2.10427}, pages = {1 -- 7}, year = {2024}, abstract = {The growing utilization of remote sensing data in lake studies provides crucial spatial insights into biogeochemistry and biology. However, clarity regarding the development and intended use of remote sensing products is often lacking. This letter aims to elucidate the tradeoffs for the utilization of remote sensing data in limnological studies with an example of based on the estimation of chlorophyll a due to its importance as a water quality indicator. The analysis initiates with a meticulous product selection, requiring an evaluation of its capacity to address the optical complexity of freshwater systems. Assessing atmospheric correction and product limitations ensures alignment with the study's objectives. Subsequently, rigorous validation of remote sensing products is essential, accompanied by a cautious interpretation of the data. This letter advocates for the use of remote sensing data, offering key strategies for their optimal utilization in lake studies.}, language = {en} } @article{ArroyoAbascalDegenetal.2024, author = {Arroyo, Hector Linares and Abascal, Angela and Degen, Tobias and Aub{\´e}, Martin and Espey, Brian R. and Gyuk, Geza and H{\"o}lker, Franz and Jechow, Andreas and Kuffer, Monika and S{\´a}nchez de Miguel, Alejandro and Simoneau, Alexandre and Walczak, Ken and Kyba, Christopher C. M.}, title = {Monitoring, trends and impacts of light pollution}, series = {Nature Reviews Earth \& Environment}, journal = {Nature Reviews Earth \& Environment}, publisher = {Springer Nature}, doi = {10.1038/s43017-024-00555-9}, pages = {1 -- 14}, year = {2024}, abstract = {Light pollution has increased globally, with 80\% of the total population now living under light-polluted skies. In this Review, we elucidate the scope and importance of light pollution and discuss techniques to monitor it. In urban areas, light emissions from sources such as street lights lead to a zenith radiance 40 times larger than that of an unpolluted night sky. Non-urban areas account for over 50\% of the total night-time light observed by satellites, with contributions from sources such as transportation networks and resource extraction. Artificial light can disturb the migratory and reproductive behaviours of animals even at the low illuminances from diffuse skyglow. Additionally, lighting (indoor and outdoor) accounts for 20\% of global electricity consumption and 6\% of CO2 emissions, leading to indirect environmental impacts and a financial cost. However, existing monitoring techniques can only perform a limited number of measurements throughout the night and lack spectral and spatial resolution. Therefore, satellites with improved spectral and spatial resolution are needed to enable time series analysis of light pollution trends throughout the night.}, language = {en} } @article{VegaHoelkerZielinskaDabkowskaetal.2024, author = {Vega, Catherine Perez and H{\"o}lker, Franz and Zielinska-Dabkowska, Karolina M and Jechow, Andreas}, title = {Polarised light pollution on river water surfaces caused by artificial light at night from illuminated bridges and surroundings}, series = {Journal of Limnology}, volume = {83}, journal = {Journal of Limnology}, publisher = {PAGEPress}, doi = {10.4081/jlimnol.2024.2173}, pages = {1 -- 13}, year = {2024}, abstract = {Artificial light at night originating from bridge illumination can cause polarised light pollution when it is reflected at water body surfaces. This alters the optical conditions of a river at night and potentially interferes with natural polarisation signals from, for example, moonlight. Therefore, this type of light pollution could detrimentally change the behaviour of organisms sensitive to polarised light, a navigational cue and signal known to be used e.g. by flying water-seeking insects to detect suitable aquatic habitats to reproduce and lay eggs. So far, polarised light pollution from artificial light at night is understudied. Here, we quantify polarised light pollution at the water's surface near seven illuminated bridges crossing the river Spree in Berlin. Our measurements show for the first time, that nocturnal bridge illumination induces polarised light pollution towards potential flying paths of polarotactic aquatic insects. On average, around 9\% of the water surfaces at the investigated bridges were highly polluted by polarised light, with values ranging between 3 and 12 \% for each bridge. Thus, polarised light pollution from artificial light at night is an emergent pollutant for aquatic systems. Future work on this topic should include more comprehensive measurements, further ecological studies on its impacts and the development of sustainable lighting solutions that can contribute to the protection of riverine nightscapes.}, language = {en} } @article{CzarneckaGrubisicPilottoetal.2025, author = {Czarnecka, Magdalena and Grubisic, Maja and Pilotto, Francesca and Jechow, Andreas and H{\"o}lker, Franz}, title = {Colours of the Night: Spectrum-Specific Impacts of Light Pollution on Biota}, series = {Global Change Biology}, volume = {31}, journal = {Global Change Biology}, number = {10}, publisher = {Wiley}, doi = {10.1111/gcb.70569}, pages = {1 -- 15}, year = {2025}, abstract = {Artificial light at night (ALAN) disrupts ecosystems by altering natural light cycles and affecting the physiology and behaviour of species, and represents a widespread and increasingly recognised global ecological threat. This meta-analysis investigates the effects of varying wavelengths and illuminance levels of ALAN on organisms. Broad-spectrum 'cool' light, enriched with blue and ultraviolet radiation, strongly disrupts circadian rhythms, melatonin production and nocturnal activity. However, contrary to common assumptions, broad-spectrum 'warm' light can be nearly as impactful as broad-spectrum 'cool' light lacking ultraviolet radiation, despite the predominant influence of short wavelengths on physiological processes. The impact of ALAN is not consistently dose-dependent, as even low light levels (\< 5 lx) can cause substantial biological disruptions. Thus, effective mitigation strategies require tailored solutions to specific ecological contexts and should generally avoid nocturnal illumination unless clearly needed, as there is no single 'safe dose' and 'safe spectrum' of ALAN.}, language = {en} } @article{RadingerBraunJechowetal.2026, author = {Radinger, Johannes and Braun, Marlon and Jechow, Andreas and H{\"o}lker, Franz and Michiels, Niko K. and Feldhege, Fritz and Roser, Phillip and Arlinghaus, Robert}, title = {Effectiveness of fluorescent angling lures on catch outcomes in European perch (Perca fluviatilis) under ambient light conditions}, series = {Canadian Journal of Fisheries and Aquatic Sciences}, volume = {83}, journal = {Canadian Journal of Fisheries and Aquatic Sciences}, publisher = {Canadian Science Publishing}, doi = {10.1139/cjfas-2025-0084}, pages = {1 -- 16}, year = {2026}, abstract = {Anecdotal reports in angling media suggest that using fluorescent lures may increase catch rates in dim light or at high turbidity. We conducted a controlled angling experiment, comprising 501 30-min experimental fishing trials in three meso- to eutrophic waterbodies and assessed catch rates and sizes of European perch (Perca fluviatilis) caught when offered two soft plastic lures (fluorescent vs. non-fluorescent) with similar reflective spectra. We also examined fluorescent properties of a range of market-available lures and modelled the experimental lure's fluorescing effects under natural lake light. Considering the specific light environment of the study waters, the experimental fluorescent lure could get excited by downwelling visible daylight and fluoresce at depths of up to 3 meters. Based on a sample catch of 331 perch, and after controlling for interactions with illuminance, cloud cover, water depth and daytime, the fluorescence of the experimental lure did, however, neither affect the catch rate nor the size of perch caught. Lure fluorescence maybe less important than many anglers believe, but further studies in different lake conditions are needed.}, language = {en} } @article{DickersonAndreasNoessleretal.2026, author = {Dickerson, Ashton L. and Andreas, Jechow and N{\"o}ßler, Michelle and Walles, Tim J. and Berger, Stella A. and H{\"o}lker, Franz and Nejstgaard, Jens C.}, title = {High-resolution in situ imaging reveals size-specific moonlight responses in zooplankton diel vertical migration}, series = {Scientific Reports}, volume = {16}, journal = {Scientific Reports}, number = {1}, publisher = {Nature}, doi = {10.1038/s41598-026-36105-0}, pages = {1 -- 14}, year = {2026}, abstract = {Light is the primary cue driving zooplankton diel vertical migration (DVM), a strategy that balances predation risk with resource access. However, DVM is often oversimplified, with limited consideration of how light-driven risks and resource needs vary across taxa and life stages. This simplification is partly due to constraints on collecting high-resolution, size-resolved data —especially at night, when subtle shifts in illumination reshape nocturnal risk landscapes. To overcome these limitations, we deployed a high-resolution in situ modular Deep-focus Plankton Imager and an image-recognition approach to quantify fine scale DVM and body sizes of Cladocerans and Copepods in Lake Stechlin, Germany. Data was collected from day into night and across moonrise and was compared with environmental data from vertical profiling sondes. Typical DVM patterns emerged, with deeper daytime distributions, however, moonlight introduced additional behavioural complexity: larger individuals avoided illuminated layers, likely managing predation risk, while smaller individuals moved into these layers, possibly exploiting foraging opportunities and reduced risk. These light-mediated shifts were further shaped by ecological conditions; copepods tracked food-rich layers regardless of light levels at night, while cladocerans showed light-dependent responses to both temperature and food, such that light caused them to avoid otherwise favourable (warm, food-rich) layers. Our approach provides new insight into how zooplankton navigate nocturnal lightscapes, revealing size- and taxon-specific strategies. By establishing size-dependent responses to natural moonlight, this work provides a crucial baseline for predicting how artificial light at night may restructure zooplankton communities and destabilize freshwater food webs.}, language = {en} } @article{DietenbergerJechowKalinkatetal.2024, author = {Dietenberger, Manuel and Jechow, Andreas and Kalinkat, Gregor and Schroer, Sibylle and Saathoff, Birte and H{\"o}lker, Franz}, title = {Reducing the fatal attraction of nocturnal insects using tailored and shielded road lights}, series = {communications biology}, volume = {7}, journal = {communications biology}, publisher = {Nature}, doi = {10.1038/s42003-024-06304-4}, pages = {1 -- 12}, year = {2024}, abstract = {The attraction of insects to artificial light is a global environmental problem with far-reaching implications for ecosystems. Since light pollution is rarely integrated into conservation approaches, effective mitigation strategies towards environmentally friendly lighting that drastically reduce insect attraction are urgently needed. Here, we tested novel luminaires in two experiments (i) at a controlled experimental field site and (ii) on streets within three municipalities. The luminaires are individually tailored to only emit light onto the target area and to reduce spill light. In addition, a customized shielding renders the light source nearly invisible beyond the lit area. We show that these novel luminaires significantly reduce the attraction effect on flying insects compared to different conventional luminaires with the same illuminance on the ground. This underlines the huge potential of spatially optimized lighting to help to bend the curve of global insect decline without compromising human safety aspects. A customized light distribution should therefore be part of sustainable future lighting concepts, most relevant in the vicinity of protected areas.}, language = {en} } @article{DietenbergerJechowSannetal.2025, author = {Dietenberger, Manuel and Jechow, Andreas and Sann, Manuela and H{\"o}lker, Franz}, title = {Shedding light on dark taxa: exploring a cryptic diversity of parasitoid wasps affected by artificial light at night}, series = {Scientific Reports}, volume = {15}, journal = {Scientific Reports}, publisher = {Nature}, doi = {10.1038/s41598-025-88111-3}, pages = {1 -- 12}, year = {2025}, abstract = {Artificial light at night (ALAN) contributes to the globally observed insect decline. ALAN attracts nocturnal insects from their native ecosystems and disturbs their functions in the food web. Road lights in this context are ubiquitous and relevant ALAN sources that are often not considered in conservation approaches. In a previous study we showed that shielded LED road lights are suited to be part of conservation measures by effectively reducing the attraction of nocturnal insects. Here we show that this positive effect holds true for parasitoid wasps in an experimental BACI design (Before-After-Control-Impact). Combining morphological with molecular and phylogenetic analyses, we identified 106 individuals (62 morphotypes) of a minimum of 45 genera out of 13 Hymenoptera families. We were able to identify 21 species, 11 of which are newly reported in Southern Germany (Baden-W{\"u}rttemberg). Further combining knowledge on life history and host appearance from our data and the literature, we discuss potential impacts of ALAN ranging from an influence on nocturnal pollination via parasitoid pressure on moth species and biological control of invasive pest species to tritrophic interactions between primary and secondary parasitoids. We conclusively think that shielded LED road lights will reduce the ecological impact of ALAN on parasitoid wasps in a large and undescribed number of taxa with different host associations, likely affecting associated ecosystem functions such as biological control.}, language = {en} }