TY - JOUR A1 - Fonvielle, Jeremy A1 - Bistarelli, Lukas Thuile A1 - Tao, Yile A1 - Woodhouse, Jason N. A1 - Shatwell, Tom A1 - Villalba, Luis A. A1 - Berger, Stella A. A1 - Kyba, Christopher C. M. A1 - Nejstgaard, Jens C. A1 - Jechow, Andreas A1 - Kupprat, Franziska A1 - Stephan, Susanne A1 - Walles, Tim J. W. A1 - Wollrab, Sabine A1 - Hoelker, Franz A1 - Dittmar, Thorsten A1 - Gessner, Mark O. A1 - Singer, Gabriel A. A1 - Grossart, Hans-Peter T1 - Skyglow increases cyanobacteria abundance and organic matter cycling in lakes JF - Water Research N2 - Artificial light propagating towards the night sky can be scattered back to Earth and reach ecosystems tens of kilometres away from the original light source. This phenomenon is known as artificial skyglow. Its consequences on freshwaters are largely unknown. In a large-scale lake enclosure experiment, we found that skyglow at levels of 0.06 and 6 lux increased the abundance of anoxygenic aerobic phototrophs and cyanobacteria by 32 (+/- 22) times. An ecosystem metabolome analysis revealed that skyglow increased the production of algal-derived metabolites, which appeared to stimulate heterotrophic activities as well. Furthermore, we found evidence that skyglow decreased the number of bacteria-bacteria interactions. Effects of skyglow were more pronounced at night, suggesting that responses to skyglow can occur on short time scales. Overall, our results call for considering skyglow as a reality of increasing importance for microbial communities and carbon cycling in lake ecosystems. Y1 - 2025 U6 - https://doi.org/10.1016/j.watres.2025.123315 SP - 1 EP - 11 PB - Elsevier ER - TY - JOUR A1 - Jechow, Andreas A1 - Bumberger, Jan A1 - Palm, Bert A1 - Remmler, Paul A1 - Schreck, Günter A1 - Ogashawara, Igor A1 - Kiel, Christine A1 - Kohnert, Katrin A1 - Grossart, Hans-Peter A1 - Singer, Gabirel A. A1 - Nejstgaard, Jens C. A1 - Wollrab, Sabine A1 - Berger, Stella A. A1 - Hölker, Franz T1 - Characterizing and Implementing the Hamamatsu C12880MA Mini-Spectrometer for Near-Surface Reflectance Measurements of Inland Waters JF - Sensors N2 - 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. Y1 - 2024 U6 - https://doi.org/10.3390/s24196445 VL - 24 IS - 19 SP - 1 EP - 14 PB - MDPI ER - TY - JOUR A1 - Dickerson, Ashton L. A1 - Andreas, Jechow A1 - Nößler, Michelle A1 - Walles, Tim J. A1 - Berger, Stella A. A1 - Hölker, Franz A1 - Nejstgaard, Jens C. T1 - High-resolution in situ imaging reveals size-specific moonlight responses in zooplankton diel vertical migration JF - Scientific Reports N2 - 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. Y1 - 2026 U6 - https://doi.org/10.1038/s41598-026-36105-0 VL - 16 IS - 1 SP - 1 EP - 14 PB - Nature ER -