Blaues Kolloquium
Biodiversity Seminar
Speaker: Alessandro Manfrin (RPTU University Kaiserslautern-Landau)
Artificial light at night (ALAN) is a widespread and increasing anthropogenic disturbance, with global emissions rising 3–6% annually. Despite its prevalence, its ecological impacts on freshwater systems and adjacent terrestrial habitats remain poorly understood, especially in the presence of co-occurring stressors. We investigated ALAN effects across multiple biological groups and across ecosystems, from periphyton to aquatic insects and terrestrial arthropods. White LED lighting reduced periphyton biomass by ~60% with potential cascading consequences for primary production, nutrient cycling, and the nutritional quality of basal resources. ALAN affected aquatic insect emergence and dispersal in terrestrial ecosystems, acting as both an attractive ecological trap and a barrier that can inhibit movement across dark–light boundaries. Aquatic and terrestrial insects were attracted to street lighting nearby streams, with Chironomidae responding over distances up to 1800 m. Altered insect dispersal modified prey availability in riparian areas, which in turn affected the abundance and composition of ground-dwelling arthropods, such as spiders, ultimately leading to shifts in their diets. Recently, in a mesocosm experiment, ALAN reduced crayfish nocturnal activity but did not alter predation on emerging insects. Overall, our results highlight ALAN as a pervasive driver of ecological change across aquatic and terrestrial boundaries, with significant consequences for biodiversity and trophic interactions.
Biodiversity Center WSL