Ecological impacts of nocturnal artificial lighting along the linear transport infrastructures and their dependencies. Influence of LED light parameters on the movements of bats
Incorporating transport infrastructures into the ecological functionality of territories implies taking into account the impacts of pollution caused by transport infrastructures on dependencies and adjacent ecosystems. In particular, light pollution induced by the use of night-time artificial lighting alongside transport infrastructure disturbs the functioning of peripheral ecosystems. It is therefore crucial to propose recommendations for lighting management, in particular in terms of threshold values, which could be incorporated as technical specifications for transport infrastructure managers and lighting professionals. This requirement involves measuring and comparing the effect of different light parameters of new LED technologies on the use of space by sensitive species while foraging and transiting. The objective of this project is to characterize the effect of these parameters on the movements of bats, an indicator group of major conservation concern. The first study, possible thanks to the existence of a unique experimental set-up in the Netherlands (Netherlands Institute of Ecology, NIOO-KNAW), will characterize the combined effect of intensity, light spectrum and duration of illumination of LED streetlights on foraging and transiting bats movements. We will use an innovative acoustic trajectory tool (CESCO-MNHN) to reconstruct the trajectories of bats around the lamp in 3D. We will thus estimate threshold values for each parameter to be integrated in transport infrastructure lighting strategies. In order to verify their effectiveness in situ, the second study will assess the relevance of these thresholds in a multi-infrastructure context where ecological, social and regulatory issues are confronted. The study will be conducted along a waterway (the Canal du Midi which is bordered by bicentennial plane trees, i.e. ecological corridor) surrounded by 2 bike paths and 2 roads recently equipped with white LEDs. The analysis of the flight behavior of several species of bats will be based on an approach by trait for generalization. Our study results will add to the light management recommendations to be deployed on a large scale. Measures identified as ecologically relevant will naturally be put in perspective with the social and regulatory expectations (safety) of the users and light managers (Laplace). In this way, surveys will be carried out with local residents, institutions and lighting designers (LISST and THEMA) in order to assess their perceptions of lighting and to characterize trade-offs between different ecological issues. Thus, the project will identify the levers of actions that allow the development of integrated, operational and broadly applicable lighting strategies to limit these impacts on ecosystems.