Light pollution is a modern environmental problem. The scale of light pollution is increasing yearly and is negatively affecting the functioning of terrestrial and aquatic ecosystems. Of the aquatic ecosystems, marine ecosystems are the most studied, while there is very little information on the effect of artificial lighting on freshwater ecosystems. Among freshwater aquatic organisms, there are relatively little data on the effect of artificial light on crustaceans and fish, while we could find no meaningful data on the effect of artificial light on molluscs are practically absent. Here we test whether different types of artificial lighting, differing in their spectra, affect the activity of the Holarctic mollusc Radix auricularia. For this, we used two light sources (with warm and cold light) and a 1-m long aquarium. We found that both light sources affect individuals of this species, but the effects of this exposure are different. Artificial lighting (depending on the spectral characteristics) can increase the activity of molluscs of this species or reduce it. In the long term, the impact on the ecosystem will depend on the type of water body where light pollution is present, where individuals of this species live, and the type of light sources
