Here’s a short introduction to our project activities, providing insight into the behind-the-scenes development of our idea and its objectives

Cover photo credit: Johanne Chalifour/jonaturzen 

Even though European Commission recognized light pollution as a new type of fast-spreading environmental change, regulations on light pollution across the EU are missing. One of the reasons for this is the absence of data about the adverse effects on wildlife. The degradation of natural dark imposed by artificial light puts significant pressure on biological systems. Negative effects are expected across a range of animal taxa.

Amphibians are considered as most threatened group globally due to their sensitivity to environmental change. Taking into account their role in ecosystems and conservation concerns, there is a need for investigating the effects of light pollution on this group. Project ENLIGHT aims to determine the biological effects caused by long-term exposure to LED light at night on crested newts species Triturus ivanbureschi and T. macedonicus. The novelty of the project ENLIGHT lies in the proposed experimental plan that considers: 

• tailed amphibians as a model organism; 

• multilevel biological effects covering developmental and survival rate, day/night activity, metabolic rates; 

• corticosterone levels; 

• antioxidant system and oxidative damage; 

• exposure to environmentally realistic intensities of artificial light at night (5 lux and 30 lux); 

• following effects across two life stages (larval and juvenile) and two environments (freshwater and terrestrial); 

• delayed effects of light pollution through phenomena of ontogenetic carry-over effects and hormesis; 

• and determination of light color temperature with less negative effects (2700 K or 6000 K). 

Project ENLIGHT will also focus on increasing awareness of light pollution and a mechanistic approach to improve conservation actions in protecting amphibians. This is especially important, particularly given the current widespread declines associated with this taxon. Knowledge about the adverse effects of artificial light at night will support the development of guidelines on light pollution and conservation plans.

The ENLIGHT project aims to determine the impact of ALAN on amphibians and support the development of guidelines on light pollution and conservation plans. The main goal of ENLIGHT is to assess the biological effects caused by long-term exposure to the nocturnal LED light on two endangered crested newts species (Triturus ivanbureschi and T. macedonicus, Urodela, Amphibia).

The specific objectives of the ENLIGHT project are to:

• Determine the biological effects of different intensities and color temperatures of ALAN on aquatic larvae 

• Assess the direct biological effects of ALAN on terrestrial juveniles

• Assess delayed biological effects of exposure to ALAN during the larval stage on juveniles (ontogenetic carry-over and hormetic response) 

• Communicate the scientific information to different stakeholders (scientific community, conservation, managers, regulators and the general public), and enhance public awareness about light pollution

ENLIGHT will be focused on the direct and indirect effects of ALAN on two crested newts (T. macedonicus and T. ivanbureschi), through the aquatic larval stages, metamorphosis and terrestrial juvenile stage. Namely, ENLIGHT aims to identify biological responses caused by two environmentally relevant intensities of LED light (5 lux and 30 lux) and two color temperatures (warm – 2700 K and cold – 6000 K). The LED light will be used as a predominant outdoor light source. An intensity of 5 lux is encountered in most areas hosting amphibians and 30 lux corresponds to the light intensity perceived in public gardens and emitted by street lights. Besides light intensity, the color temperature of LED light is important to determine whether or not, and the degree to which, a species is affected by ALAN. A general trend in the literature shows that cooler color temperatures (higher than 3000K) have more negative effects on nocturnal wildlife (insects, mammals and birds) compared to warmer color temperatures (lower than 3000K) (Longcore et al., 2018). Therefore, this project will also compare the degree of effects that the same intensity of light with different color temperatures can have on amphibians.

A biological response will be followed through multiple endpoints: developmental and survival rate; morphological (differences in shape and size); whole-organism performance (day/night activity); whole-organism physiology (metabolic rates); neuroendocrine response (levels of corticosterone); oxidative stress (antioxidant system and oxidative damage). It is expected that both species exposed to ALAN will change day/night patterns of physical activity and metabolic rates and experience physiological stress. This condition will trigger accelerated development, shorten the larvae period and lead to earlier metamorphosis and transition to a terrestrial environment. The greatest alterations are expected in individuals exposed to higher light intensity and cold light.

The next phase of the ENLIGHT project will be focused on the direct effects of ALAN on the juveniles of T. ivanbureschi, and the delayed effects of early life stress on developmental, morphological and physiological parameters. The assumption is that terrestrial juveniles that developed under artificial light as larvae will experience detrimental carry-over effects even if they do not experience light pollution in the juvenile life stage. Effects will be observed as greater physiological stress in comparison to juveniles that trough whole life developed under natural photoperiods. 

If juveniles are exposed to ALAN it can be expected that early-life stressed individuals will cope better with light pollution in relation to juvenile individuals that did not experience light pollution before. Exposure to a stressor during the larval stage may promote the adaptive hormetic response of resistance and resilience. Investigation of delayed effects of light pollution and multiple effects across life stages on an organism's phenotype is a central predictor of individual fitness and a key issue in conservation biology, especially in species with complex life histories and ontogenetic shifts.

The Data Management Plan of the ENLIGHT project will follow FAIR (Findable, Accessible, Interoperable, and Reusable) principles and Open Science Policy. The ENLIGHT project will generate research data in the form of datasets, video and image files.