Artificial light at night (ALAN) has the potential to alter ecological processes such as the natural dynamics of predator-prey interactions. Although understanding of ALAN effect on faunal groups has increased in recent years, few studies have explicitly tested for direct consequences of ALAN on predator-prey systems. Here, we evaluated the effect of ALAN on juvenile mortality due to cannibalism and general predation of the South American intertidal burrowing crab Neohelice granulata, a key ecosystem engineer of salt marshes. For this, we conducted tethering and crab enclosure experiments for both night and day periods during successive tidal floods in a semidiurnal tidal regime. Both experimental approaches were deployed simultaneously in the field and they lasted four consecutive days during new moon nights. ALAN was simulated by a white LED lamp (30W) with a solar panel as a source of power in five separated areas selected as replicates. For general predation, juvenile survival under ALAN was 44% lower than during the daytime and 61% lower than under natural dark conditions. For cannibalism, juvenile survival under ALAN and during the daytime was similar and about 30% lower than under natural dark conditions. We also found that the abundance of adult male crabs (cannibals) under ALAN was nearly five times higher than at natural dark conditions. Our field experiments provide evidence that ALAN can increase the mortality of juvenile crabs and is at least partially driven by cannibalistic interactions.

夜间人造光（ALAN）可能会改变生态过程，例如捕食者与价格相互作用的自然动力学。尽管近年来对ALAN对动物群影响的理解有所增加，但很少有研究明确测试ALAN对捕食者－猎物系统的直接影响。在这里，我们评估了ALAN对同类相食和南美潮间带穴蟹Neohelice granulata的一般捕食引起的幼年死亡率的影响，盐沼的关键生态系统工程师。为此，我们在半日潮型连续潮汐洪水期间的白天和黑夜进行了系绳和围捕蟹的实验。两种实验方法在野外同时部署，并且在新月之夜连续进行了四天。ALAN由白色LED灯（30W）进行模拟，该灯在五个独立的区域中选择了太阳能电池板作为电源，作为复制品。对于一般的捕食，ALAN下的幼虫存活率比白天低44％，比自然黑暗条件下低61％。对于食人族，ALAN和白天的幼虫存活率相似，比自然黑暗条件下的幼虫存活率低约30％。我们还发现，在ALAN下，成年雄性蟹（食人鱼）的丰度比自然黑暗条件下的丰度高出近五倍。我们的现场实验提供了证据，表明ALAN可以增加幼蟹的死亡率，并且至少部分是由食人性相互作用驱动的。