Abstract
The prevalence of artificial light at night can alter nocturnal environments and affect animal behavior. We investigated how the presence of artificial light affects the activity of the variable crayfish Cambarus latimanus by manipulating light intensities and providing a choice between dark and lighted environments. Crayfish were more active in the absence of artificial light and preferred dark environments even when light intensities were very low (~5 lx). Our results suggest that crayfish may increase sheltering behavior and seek out darkness in the presence of artificial light, potentially increasing shelter competition and reducing contributions of crayfish to ecosystem function.