Artificial light pollution: Shifting spectral wavelengths to mitigate physiological and health consequences in a nocturnal marsupial mammal

Abstract

The focus of sustainable lighting tends to be on reduced CO emissions and cost savings, but not on the wider environmental effects. Ironically, the introduction of energy-efficient lighting, such as light emitting diodes (LEDs), may be having a great impact on the health of wildlife. These white LEDs are generated with a high content of short-wavelength 'blue' light. While light of any kind can suppress melatonin and the physiological processes it regulates, these short wavelengths are potent suppressors of melatonin. Here, we manipulated the spectral composition of LED lights and tested their capacity to mitigate the physiological and health consequences associated with their use. We experimentally investigated the impact of white LEDs (peak wavelength 448 nm; mean irradiance 2.87 W/m ), long-wavelength shifted amber LEDs (peak wavelength 605 nm; mean irradiance 2.00 W/m ), and no lighting (irradiance from sky glow < 0.37 × 10 W/m ), on melatonin production, lipid peroxidation, and circulating antioxidant capacity in the tammar wallaby (Macropus eugenii). Night-time melatonin and oxidative status were determined at baseline and again following 10 weeks exposure to light treatments. White LED exposed wallabies had significantly suppressed nocturnal melatonin compared to no light and amber LED exposed wallabies, while there was no difference in lipid peroxidation. Antioxidant capacity declined from baseline to week 10 under all treatments. These results provide further evidence that short-wavelength light at night is a potent suppressor of nocturnal melatonin. Importantly, we also illustrate that shifting the spectral output to longer wavelengths could mitigate these negative physiological impacts.

Artificial light at night as an environmental pollutant: An integrative approach across taxa, biological functions, and scientific disciplines

“…Three articles in our special issue confirmed this evidence for insect phototaxis (Donners et al, 2018), corticosterone levels in birds (Alaasam et al, 2018) and oxidative status in wallabies (Dimovski & Robert, 2018). Thus, it seems that white light, which contains a high proportion of blue wavelengths and is one of the most common light sources used for nocturnal illumination, should be avoided.…”

Light Pollution, Circadian Photoreception, and Melatonin in Vertebrates

“…This indicates species-and wavelength-specific sensitivity of melatonin suppression in sighted mammals, possibly as a result of different adaptive life-history strategies at the retinal level [158]. minimizing emission of short wavelengths in the spectral output of light sources may be a promising approach to mitigate effects of on melatonin levels in mammals, as it was recently shown for nocturnal marsupial species, tammar wallaby (Macropus eugenii) [159]. More studies that compare effects of different light sources on a wider diversity of species with different life histories are highly needed.…”

Artificial light at night causes reproductive failure in clownfish

“…Given that ALAN has the potential to disrupt the natural cycles of light and dark that are used ubiquitously to initiate or regulate circadian, lunar and annual rhythms, more research is needed on other aspects of fitness and other organisms to understand the species-specific impacts of light pollution in the marine environment. Furthermore, ALAN is an anthropogenic disturbance that can simultaneously, directly affect multiple trophic levels through, for example, modifying behaviour [32] and physiology [33], attraction of predator and prey species (e.g. [34,35]), and shifting temporal niches [18,36].…”