Cascading effects of artificial light at night: resource-mediated control of herbivores in a grassland ecosystem

Abstract

Artificial light at night has a wide range of biological effects on both plants and animals. Here, we review mechanisms by which artificial light at night may restructure ecological communities by modifying the interactions between species. Such mechanisms may be top-down (predator, parasite or grazer controlled), bottom-up (resource-controlled) or involve non-trophic processes, such as pollination, seed dispersal or competition. We present results from an experiment investigating both top-down and bottom-up effects of artificial light at night on the population density of pea aphids Acyrthosiphon pisum in a diverse artificial grassland community in the presence and absence of predators and under low-level light of different spectral composition. We found no evidence for top-down control of A. pisum in this system, but did find evidence for bottom-up effects mediated through the impact of light on flower head density in a leguminous food plant. These results suggest that physiological effects of light on a plant species within a diverse plant community can have detectable demographic effects on a specialist herbivore.

Night-time lighting alters the composition of marine epifaunal communities

“…These lux levels were comparable to those found at the water's surface adjacent to nearby assemblages of epifaunal invertebrates exposed to night-time lighting (5-21.6 lux). The spectral power distribution of the make and model of cool white LED strips used is provided in Bennie et al [8]. All lights were powered via a 12 V battery trickle charged using a solar panel (Sunware 24 W), and switched on at dawn and off at dusk using a CellOptick 12V photocell.…”

Out of the Dark: Establishing a Large-Scale Field Experiment to Assess the Effects of Artificial Light at Night on Species and Food Webs

“…The study area presented here is situated in grassland habitat adjacent to an agricultural drainage ditch system, using squares of street lights and luminaires with commonly used high-pressure sodium lamps which have a yellowish spectrum and a color temperature of 2000 K. The Dutch study sites are located at forest edges and apply different color spectra of light in single rows of street lights [26], while the British experiment encompasses experimental grassland "mesocosms" located in a grassland area with selected model species and two different artificial light treatments using light-emitting diodes (LEDs) [27].…”

“…For highly mobile organisms whose home range is larger than one or both fields, our setup may not be suitable for testing certain hypotheses because of scale-dependence. Studies of long-term effects that require sustained illumination of treatment sites could be carried out using additional sites (not yet planned) or through collaboration with other infrastructures [26,27]. Here, we describe the study area and the newly constructed infrastructure including a characterization of the illumination with photometric measurements.…”

“…Apart from two recent long-term experimental illumination studies that included several generations of key species [26,27], the effects of ALAN have only been studied in laboratory experiments (e.g., [15,28]) or by making observations at or near existing public light infrastructure [29][30][31][32]. The limitations of these approaches include an inability to predict community-and ecosystem-level effects from laboratory experiments, and the potentially confounding effect of studying communities of organisms that are already accustomed to the presence of ALAN [12].…”

The dark side of light: how artificial lighting is harming the natural world

“…The scientists discovered that amber light and, to a lesser extent, white, suppressed flowering in the trefoil (Lotus pedunculatus) 11 . And there was a cascade effect in the amber-lit boxes.…”