Case Study

Artificial light at night and turtles

Artificial light at night (ALAN) has been identified as a high-risk threat in the Recovery Plan for Marine Turtles (2017-2027) (Commonwealth of Australia 2017) in Australia. This is because light is an important cue for dispersing turtle hatchlings and artificial light can disrupt this process. In 2023, AIMS and Woodside jointly funded a project led by a dedicated research fellow in collaboration with Pendoley Environmental and the WA Department of Biodiversity, Conservation and Attractions, to conduct a focused scientific investigation of priority research questions on the effects of ALAN on the dispersal of newly emerged turtle hatchlings. The first objective was to conduct a systematic literature review that summarises the impact of ALAN on marine turtle hatchlings and identify knowledge gaps that can guide AIMS’ research.

In 2025, field research was completed with the objective to develop phototaxis thresholds for marine turtle hatchlings to environmentally realistic spectral signatures of light. Using an apparatus known as a Y-maze under controlled laboratory conditions, the researchers tested how each hatchling responded to different light levels compared to darkness, to understand the thresholds at which the hatchlings’ ability to find the ocean may be hampered. The researchers tested three different types of light on the turtles: two were types of light emitting diodes, or LEDs, that are commonly used, with the aim of establishing intensity, or brightness levels that are minimally attractive to hatchlings for these lights. They also tested a blended spectrum, mimicking the light spectrum typically found in coastal areas occupied by humans. The control was no light (darkness) in the other arm of the Y-maze. The aim is to pinpoint the intensity that has minimal attraction of hatchlings for each of the different types of light tested. This research is continuing in 2026.

Turtle hatchlings collected for the ALAN turtle project. Hatchlings were returned to the beach the same night. Violeta Brosig; and Turtle hatchling in the Y-maze. Daniel Gomez Isaza