The Effect of Electric Bridge Lighting at Night on Mayfly Activity

Dorukalp Durmus,Shawn Good,Benjamin Basom,Julian Wang

doi:10.3390/en14102934

Abstract

Phototactic and polarotactic aquatic insects, such as mayflies, can be drawn to electric lighting on bridges at night. Past research investigating the effect of light intensity, polarization, and spectrum on mayflies suggests that a combination of different techniques can reduce the number of mayflies attracted to bridges. Here, various lighting strategies are systematically tested on Veterans Memorial Bridge in Pennsylvania to investigate the effect of lighting on mayflies and address safety concerns caused by their mass crowding. Isolated trials on different parts of the bridge tested the effectiveness of correlated color temperature, chromaticity, ultraviolet radiation, shielding, and polarization. Results indicate that mayflies were more attracted to ultraviolet radiation, blue and green light, and polarized light than other lighting conditions. Shielding was minimally effective in reducing the number of mayflies on the bridge when supported by the change in light source spectrum. While the correlated color temperature did not result in a statistically significant impact, the spectral power distribution of the light sources was a major influencer for mayfly activity. Future research should investigate the effect of radiant intensity and timing on mayfly activity. Smart solid-state lighting systems and controls can also be used to adjust the light levels when needed to reduce adverse effects on aquatic insects and aid traffic safety.

Highlights

Outdoor lighting design requires careful consideration of the conflicting needs of humans, animals, and plants
The greatest reduction of mayfly numbers is associated to the lighting condition with 2200 K correlated color temperature on the bridge and the green-blue polarized light under the bridge
The variations in the number of mayflies across the tota1l0 toifm17e range are relatively smaller for certain lighting conditions, such as 2200 K + green light and 2200 K + green/blue polarized light

Summary

Introduction

Outdoor lighting design requires careful consideration of the conflicting needs of humans, animals, and plants. Unwarranted electric light at night can cause disruption for animals and plants, and the attraction of insects to light sources can reduce visibility and safety for humans, especially in urban areas. Recent research on the ecological impacts of electric light has focused on contemporary lighting technologies, such as solid-state lighting (SSL) devices. When LEDs at different correlated color temperatures (CCTs) were normalized between 400 nm and 500 nm (alleged peak sensitivity for most insects), the CCT did not significantly affect the number in the trap catch. Since the spectral output of SSL devices can be adjusted, it is possible to replace older technologies like HPS with LEDs, which enable connectivity and adaptive lighting solutions (e.g., automatic adjustment of light levels depending on environmental data collected from sensors)

Methods

Results

Discussion

Conclusion