IMPACT OF LIGHT POLLUTION ON DIFFERENT TAXA OF MIGRATORY SPECIES
(Prepared by Ms. Laetitia Nunny on behalf of the CMS Secretariat)
1.1.3 Biological impacts of light pollution
Organisms have evolved under consistent light conditions with day and night, lunar cycles and seasonality (Seymoure, 2018). Natural light is used by wildlife as a resource and to gain information about their environment (Gaston, 2013). It is also involved in mechanisms essential for regulating metabolism, growth and behaviour, including synchronisation of internal circadian clocks (Kyba et al., 2011; Falcón et al., 2020).
It is increasingly recognised that hormonal synthesis and secretion are often under circadian and circannual control, meaning that perturbation of these internal clocks will lead to hormonal imbalances and other problems (Falcón et al., 2020). Circadian rhythms are endogenous biological rhythms with 24-hour periods and though they persist without environmental cues, these cues (including light) are used by organisms to entrain their circadian rhythms (Russart and Nelson, 2018b). Light is the most effective entraining agent or zeitgeber.
In their recent review, Falcón et al. (2020) describe how:“… most of the basic functions of living organisms are controlled by these internal, genetically determined, clocks. These clocks depend absolutely on the 24 h LD2 cycle to accurately synchronize their activity with solar time, and in turn they orchestrate a myriad of downstream biochemical, physiological and behavioural events so that the right process occurs at the right time. Thus, changing the natural LD cycle cannot be without consequences for biological organisms.”