READmeFile from Artificial light at night reverses monthly foraging pattern under simulated moonlight

Mounting evidence shows that artificial light at night (ALAN) alters biological processes across levels of organization, from cells to communities. Yet, the combined impacts of ALAN and natural sources of night-time illumination remain little explored. This is in part due the lack of accurate simulations of the complex changes moonlight intensity, timing and spectra throughout a single night and lunar cycles in laboratory experiments. We custom-built a novel system to simulate natural patterns of moonlight to test how different ALAN intensities affect predator–prey relationship over the full lunar cycle. Exposure to high intensity ALAN (10 and 50 lx) reversed the natural lunar guided foraging pattern by the gastropod mesopredator <i>Nucella lapillus</i> on its prey <i>Semibalanus balanoides</i>. Foraging decreased during brighter moonlight in naturally lit conditions. When exposed to high intensity ALAN, foraging increased with brighter moonlight. Low intensity ALAN (0.1 and 0.5 lx) had no impact on foraging. Our results show that ALAN alters the foraging pattern guided by changes in moonlight brightness. ALAN impacts on ecosystems can depend on lunar light cycles. Accurate simulations of night-time light cycle will warrant more realistic insights into ALAN impacts and also facilitate advances in fundamental night-time ecology and chronobiology.

越来越多的研究证据显示，夜间人工光（artificial light at night, ALAN）会改变从细胞到群落等各级组织水平的生物过程。然而，目前关于夜间人工光与自然夜间光源的联合影响仍鲜有探索。这在一定程度上是因为实验室实验中难以精准模拟单夜及月相周期内月光强度、出现时间与光谱的复杂变化。为此我们定制搭建了一套全新的月光自然节律模拟系统，以探究不同强度的夜间人工光在完整月相周期内对捕食者-猎物关系的影响。当暴露于高强度夜间人工光（10 lx与50 lx）环境时，腹足类中型捕食者<em>Nucella lapillus</em>对其猎物<em>Semibalanus balanoides</em>的自然月光引导觅食模式发生逆转：在自然光照条件下，觅食行为会随月光亮度升高而降低；而当暴露于高强度夜间人工光环境时，觅食行为则随月光亮度升高而增强。低强度夜间人工光（0.1 lx与0.5 lx）则对觅食行为无显著影响。本研究结果表明，夜间人工光会改变由月光亮度变化引导的觅食模式。夜间人工光对生态系统的影响可能依赖于月球光照周期。精准模拟夜间光照周期，不仅能为夜间人工光的生态影响提供更贴合实际的认知，还将推动基础夜间生态学与时间生物学（chronobiology）领域的研究进展。