An assessment of ‘turtle-friendly’ lights on the sea-finding behaviour of loggerhead turtle hatchlings (Caretta caretta)
Katharine Robertson A , David T. Booth A C and Colin J. Limpus BA School of Biological Science, The University of Queensland, Qld 4072, Australia.
B Threatened Species Unit, Queensland Government Department of Environment and Heritage Protection, Brisbane, Qld 4001, Australia.
C Corresponding author. Email: d.booth@uq.edu.au
Wildlife Research 43(1) 27-37 https://doi.org/10.1071/WR15138
Submitted: 10 July 2015 Accepted: 10 January 2016 Published: 23 March 2016
Abstract
Context: It is well established that artificial light can disrupt the sea-finding ability of sea turtle hatchlings, and some manufactures are now marketing ‘turtle-friendly’ lights that are supposed to be minimally disruptive to this sea-finding behaviour. However, there have been no studies that have tested whether ‘turtle-friendly’ lights are benign to hatchling sea turtle sea-finding ability.
Aims: We tested two different types of ‘turtle-friendly’ lights (LED amber-light peak intensity 620 nm and LED red-light peak intensity 640 nm) to see whether they are disruptive to the sea-finding ability of eastern-coast Australian loggerhead turtle hatchlings.
Methods: Using standard circular-arena experiments, we assessed the directional preference of newly emerged loggerhead turtle hatchlings from the Woongarra Coast of Queensland, Australia, during different moon phases without artificial lighting and in the presence of ‘turtle-friendly’ lights.
Key results: Contrary to expectations, sea-finding ability of hatchlings was disrupted by the amber lights, particularly in the absence of a moon. The less intense red lights were less disruptive to hatchlings; however, misorientation and disorientation events still occurred when lights were within 4 m of hatchlings. The disruptive impact on sea-finding ability increased with the cumulative impact of multiple lights increasing light intensity.
Conclusions: The ‘turtle-friendly’ lights we used disrupted the sea-finding ability of eastern-coast Australian loggerhead turtle hatchlings, with the most pronounced disruption occurring under moonless conditions.
Implications: The use of amber and red LED lights adjacent to the nesting beaches of loggerhead sea turtles should be managed because this lighting has the potential to disrupt the sea-finding ability of sea turtle hatchlings.
Additional keywords: disorientation, light pollution, misorientation, sea-turtle hatchling.
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