Artificial light at night alters activity, body mass, and corticosterone level in a tropical anuran

Abstract

Photoperiod is a major factor regulating biological rhythms in animals and plants. At low latitudes, annual variation in daylength is low and species are expected to strongly rely on photic cues to reset their circadian clocks. A corollary is that individuals should be strongly affected by sudden changes in the photic regime as those generated by artificial light at night (ALAN). We tested this hypothesis in an anuran in Costa Rica (10°N). Using an outdoor experimental design, we exposed adult cane toads Rhinella marina, a broadly distributed tropical anuran species to two ALAN intensities (0.04 and 5 lx). Locomotor activity was reduced at the lowest intensity, and the activity pattern shifted from crepuscular to nocturnal. Contrary to humans and mice in which ALAN favor obesity, toads from the two exposed groups did not gain mass whereas controls did. Corticosterone was reduced at the highest intensity, a possible consequence of the reduced activity of toads or the altered regulation of their circadian pattern. Thus, the behavioral and physiological disruption that we observed supports the hypothesis of the strong reliance on photic cues to regulate circadian rhythms and control homeostasis in this intertropical anuran. Furthermore, our results suggest that the negative effects of ALAN on physiology, in particular body mass regulation, may differ between vertebrate groups, thus preventing anticipated generalization before more comparative studies have been carried out. We stress the importance of considering the impact of the changing nocturnal environment in the intertropical zone which host the largest fraction of biodiversity.

Silk sericin alleviates aberrant photoperiod-induced alterations in testicular and adrenal steroidogenesis in adult mice

“…However, Syrian hamsters react to such conditions in an opposite manner [33,34]. Similar effects are caused by ALAN, leading to weight gain and obesity in humans, mice, and Australian budgerigars but not in toads Rhinella marina [35,36]. In agreement with cited studies, in our experiment, LD photoperiod caused a significant increase in the weight of the mice after five weeks.…”

Transcriptome-wide deregulation of gene expression by artificial light at night in tadpoles of common toads

“…The higher the ALAN illuminance, the greater the deregulation of transcriptome expression. This observation had previously been noted in several species exposed to a range of ALAN levels on biological processes, such as hormonal synthesis, (Brüning et al 2015, Grubisic et al 2019, Kupprat et al 2020, activity rhythms (de Jong et al 2016, Barré et al 2020, Secondi et al 2021, reproductive physiology (Dominoni et al 2018) and individual's density (Sanders et al 2018). In addition, in our study, strong molecular impacts were obtained even at very low illuminance, 0.1 lux, corresponding to the skyglow level recorded in rural areas (Gaston et al 2013).…”

Effects of the social environment on vertebrate fitness and health in nature: Moving beyond the stress axis

“…These range from systemic immune/ metabolic disorders and cognitive impairment (Takahashi et al, 2008;Delezie and Challet, 2011;Karatsoreos et al, 2011;Cermakian et al, 2014;Rao and Androulakis, 2019), central nervous system disorders including anxiety, schizophrenia, depression, and bi-polarity amongst others (Lamont et al, 2007;McClung, 2007;Benca et al, 2009), to cell senescence (Grosbellet et al, 2015) and cancer (Sephton and Spiegel, 2003;Shilts et al, 2018). However, it is only recently, and mostly in the context of anthropogenic disturbance and urbanization (Dominoni et al, 2013(Dominoni et al, , 2016Kolbe et al, 2021;Secondi et al, 2021;Ziegler et al, 2021), that studies on wild vertebrates have focused on the extent to which chronic disruption of biological rhythms may occur in nature. Yet, social interactions have been suggested to play a key role in the regulation of biological rhythms and health (Ehlers et al, 1988;Mistlberger and Skene, 2004).…”