Six of the world’s seven marine turtle species occur in Australia and all are protected by international and national agreements and legislation. Light pollution in the coastal zone is considered a key threat to marine turtles.
In Australia, a large number of important turtle nesting sites are exposed to light pollution along the industrialised Northwest Shelf of Western Australia and the urbanised coast of Queensland. Marine turtle hatchlings generally emerge from their beach nests at night and show an innate ability to orientate towards the sea, being attracted toward the lower, brighter horizon of the sea surface.
Artificial lighting along the coast can confuse and misdirect newly emerged hatchlings by appearing brighter than the sea surface horizon. This can result in hatchlings being attracted away from the sea, increasing their risk of death by predation, dehydration or exhaustion. If hatchlings reach the ocean, artificial light on and around water (e.g. boats at anchor, jetties) can continue to disorientate them, potentially causing them to linger in nearshore waters with similar results. There is also evidence that light pollution can disrupt and deter the nesting behaviour of adult female turtles.
To reduce the impacts of lights on turtles, the Commonwealth Department of Environment and Energy is developing guidelines to manage artificial light around wildlife. The guidelines outline best practice lighting design including starting with natural darkness and only adding light when needed, and using smart controls (motion sensors, timers, etc). They recommend lowering light intensity and avoiding lights with blue wavelengths, which are particularly disruptive to turtles. Further, lights should be kept close to the ground, directed and shielded and surfaces should be non-reflective. The implementation of these recommendations to new and existing projects near turtle nesting beaches will reduce the impacts of artificial light on marine turtles.