Light pollution can create dangerous environments for fish, especially during their early life stages. This study looked at how artificial lights on coral reefs affect fish settlement and survival. We found that fish are more likely to settle on corals with artificial lights, but this also leads to a higher death rate for these fish. The lights disrupt their natural behaviors and attract predators, making survival harder. Although some fish show signs of adapting to these poor conditions, light pollution still poses a serious threat to their survival. This highlights the importance of reducing light pollution to protect marine life.
Simplified
Ecological traps, poor-quality habitats that attract animals, significantly threaten ecosystems but have rarely been documented in marine environments. In fish, early life-history events, such as larval settlement, play a key role in shaping individual survival, population stability, and community interactions. While evidence suggests that late-stage fish and invertebrate larvae exhibit a phototactic response, the effects of light pollution on larval settlement and survival remain poorly understood. Here, we simulated environmental light pollution on coral reefs using artificial light to examine its impact on fish settlement and post-settlement consequences. We found that settlement was up to eight times higher onto corals exposed to light pollution compared to those under natural conditions. However, exposure to light pollution reduced recruit survival by half, desynchronized settlement from the full moon and reduced size at settlement. We identified key mechanisms contributing to increased mortality of individuals exposed to artificial light, including disruptions in resting metabolic rhythm and higher predation (due to heightened predator attraction). Additionally, we reveal potential trait compensation in body condition and maximum metabolic rate, traits linked to fitness. However, despite these potential compensatory mechanisms, light pollution functions as a severe ecological trap for fish, attracting individuals into suboptimal environments where they experience higher mortality. This underscores the need to regulate light pollution as a critical environmental stressor.
