Artificial light at night suppresses the metabolic response of a coral reef fish to a virtual predator

Artificial light at night is an increasingly widespread feature of coastal environments and is known to alter animal physiology, but its effects on predator-prey interactions are poorly understood. Here, we show that chronic exposure to artificial light fundamentally alters metabolic responses to predation risk in a coral reef fish. Using immersive virtual reality to present a standardized visual predator stimulus while simultaneously measuring oxygen uptake, we quantified responses of wild-caught Polynesian anemonefish Amphiprion maohiensis with known histories of ambient or artificial nighttime light exposure. Fish from ambient light environments exhibited a strong anti-predator response, characterized by a suppression of metabolic rate (MR). In contrast, fish chronically exposed to artificial light increased their MR when faced with the same predator stimulus. This study demonstrates that artificial light can modify how physiological systems respond during ecologically critical interactions, making artificial light an important consideration when managing coastal systems. As light pollution expands globally, such disruption of predator-prey dynamics may have cascading consequences for energy budgets, survival and population persistence in coastal ecosystems.