Does coastal light pollution alter the nocturnal behavior and blood physiology of juvenile bonefish (Albula vulpes)?

Light pollution is a prevalent, but often overlooked, ecological concern in a variety of ecosystems. Marine environments are subjected to artificial lighting from coastal development, in addition to offshore sources, such as fishing vessels, oil platforms and cruise ships. Fish species that rely on nearshore habitats are most significantly impacted by coastal light pollution, as they are often limited to nearshore habitats due to predation risk in deeper offshore waters, particularly as juveniles. Juvenile bonefish [Albula vulpes (Linnaeus, 1758)] inhabit the nearshore environment, and are therefore exposed to coastal lighting and other watershed development impacts. Here, we assessed juvenile bonefish behavior and physiology in the presence of two common light sources: constant street lighting (high pressure sodium) and intermittent car headlights (H4 halogen). The behavioral responses were compared with a night and day control, whereas physiology was compared only with a night control. Each behavioral trial had two time periods: light and recovery (2 hrs each). Physiology (blood glucose and whole body cortisol) was assessed after an overnight 8-hr exposure. The results suggest that there is no effect of light pollution on the swimming behavior or whole body cortisol of juvenile bonefish, but that both forms of light pollution resulted in elevated blood glucose concentrations (a simple stress indicator) relative to controls, with constant light glucose levels being significantly higher. Further research is needed to understand the ecological consequences of light pollution on bonefish and other coastal marine fish using additional endpoints, assessing fish over longer time periods, and ideally combining data from the laboratory and the field.