Artificial Light at Night is recognized for its impact on various ecosystems, with coastal areas being particularly vulnerable. While a growing number of studies have identified Artificial Light at Night's impacts on species inhabiting these ecosystems, a critical gap is the limited attention that has been given to intraspecific variability in response to this stressor. This study focused on the sex-dependent influence of Artificial Light at Night on food consumption rates and absorption efficiency in males and females of the non-indigenous amphipod Ampithoe valida. Males and females were exposed to two light treatments: a natural light/dark cycle and Artificial Light at Night. Our hypothesis was that Artificial Light at Night alters the amphipod's food consumption rates and absorption efficiency, but the magnitude of these impacts is sex-dependent. Results showed that females had higher nocturnal food consumption rates under control conditions, while males showed no significant diel food consumption rates. Under Artificial Light at Night conditions, females experienced a substantial reduction in nighttime food consumption rates and absorption efficiency, suggesting stress or disrupted circadian rhythms. In contrast, males increased their nighttime food consumption rates under Artificial Light at Night, possibly exploiting a new light-induced niche. These findings highlight the need for further research on the ecological consequences of intraspecific variation in the responses to Artificial Light at Night, particularly regarding the management and conservation of ecosystems impacted by non-indigenous species.
