The dark side of light: species and community level impact of artifical night lighting

A project undertaken at the School of BioSciences, The University of Melbourne, and supervised by Dr Therésa Jones and Dr Mark Green

The global increase in the intensity of artificial light at night (LAN) is regarded as one of the most pervasive and under-appreciated forms of environmental pollution. Current LAN levels in urban environments have been linked to changes in behaviour, reductions in individual fitness, declines in species abundance and dramatic shifts in ecosystem composition. A potential explanation for these biological disruptions is that LAN lowers circulating levels of the hormone melatonin; a key regulator of day-night rhythm and a possible anti-oxidant. Melatonin is a highly conserved protein identified in all major taxonomic groups. However, most studies exploring links between LAN, melatonin levels and changes in biological process are correlational.

We will use species- and community-level assessments of invertebrates to assess the physiological  and behavioural impact of variation in both the intensity and spectra of LAN. Invertebrates are an ideal taxon since they comprise over 75% of all animals; are the most taxonomically diverse and are particularly susceptible to changes in nocturnal illumination. Our largely experimental project will deliver a major advance in our understanding of the mechanisms driving the ecological impact of artificial light at night. This is a pivotal first step for the development of sustainable urban lighting strategies that will need to balance the potential conflict of growing human demands for brighter night lighting with the adverse ecological effects this may promote.


Figure 1. Mating black field crickets (Teleogryllus commodus). The male (on the bottom) is transferring a sperm-filled spermatophore (the lighter-coloured sphere) to the female (on the top).

Figure 2. Pitfall traps illuminated with artificial LED lights at Serendip sanctuary (skyglow of Melbourne in the back ground). Photo: Jo Durrant