Abstract
Artificial light at night (ALAN), termed light pollution, is an increasingly important anthropogenic environmental pressure on wildlife. Exposure to unnatural lighting environments may have profound effects on animal physiology, particularly during early life. Here, we experimentally investigated for the first time the impact of ALAN on body mass and oxidative status during development, using nestlings of a free-living songbird, the great tit (Parus major), an important model species. Body mass and blood oxidative status were determined at baseline (=13 days after hatching) and again after a two night exposure to ALAN. Because it is very difficult to generalise the oxidative status from one or two measures we relied on a multi-biomarker approach. We determined multiple metrics of both antioxidant defences and oxidative damage: molecular antioxidants GSH, GSSG; antioxidant enzymes GPX, SOD, CAT; total non-enzymatic antioxidant capacity and damage markers protein carbonyls and TBARS. Light exposed nestlings showed no increase in body mass, in contrast to unexposed individuals. None of the metrics of oxidative status were affected. Nonetheless, our study provides experimental field evidence that ALAN may negatively affect free-living nestlings’ development and hence may have adverse consequences lasting throughout adulthood.
Highlights
Condition of the cell that occurs when there is an imbalance between pro-oxidants and antioxidants in favour of pro-oxidants leading to oxidative damage to biomolecules[18,19]
While field studies on oxidative status (OS) often rely on single point measurements and experiments on free-living animals are often unfeasible[44], we experimentally investigated effects of artificial light at night (ALAN) on OS using wild great tits and took repeated measurements as the latter is important for understanding physiological responses[44] as well as to control for confounding variables and variation generated by individuals
Artificial light at night had a significant effect on nestling body mass (F = 7.209, P = 0.009, Fig. 1; full model output is given in Supplementary Table S2)
Summary
Condition of the cell that occurs when there is an imbalance between pro-oxidants and antioxidants in favour of pro-oxidants leading to oxidative damage to biomolecules[18,19]. It is thought that oxidative stress is an important candidate mechanism underlying the effects of environmental changes on organism fitness because of its effects on growth[20], fertility[21], immune protection[22] and cellular senescence[23] It was shown in European shags (Phalacrocorax aristotelis) that fledglings with higher oxidative stress had a lower recruitment probability[24] and in great tits (Parus major) that red blood cell resistance to oxidative stress predicted fledging success[25]. Either low or high antioxidant levels do not necessarily indicate whether damage is, or, is not occurring[19], it is important to measure more than one type of marker of antioxidant protection along with markers of oxidative damage To this end, in this study, we have relied on a multi-biomarker approach in order to obtain a better understanding of oxidative status. Laboratory studies have often focused on one sex (e.g. ref. 38), we took into account that in birds, and especially in great tits, there may be sex-specific differences in oxidative status, growth rate[39,40] and environmental sensitivity (reviewed in ref. 41), and we used both male and female nestlings
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