TY - JOUR

T1 - Artificial Light at Night Causes Top‐down and Bottom‐up Trophic Effects on Invertebrate Populations

AU - Bennie, Jonathan

AU - Davies, Thomas W.

AU - Cruse, David

AU - Inger, Richard

AU - Gaston, Kevin J.

N1 - The research leading to this paper was funded by the European Research Council under the European Union's Seventh Framework programme (FP7/2007‐2013)/ERC grant agreement no. 268504 to K.J.G.

PY - 2018/11

Y1 - 2018/11

N2 - 1.Globally, many ecosystems are exposed to artificial light at night. Nighttime lighting has direct biological impacts on species at all trophic levels. However, the effects of artificial light on biotic interactions remain, for the most part, to be determined.2.We exposed experimental mesocosms containing combinations of grassland plants and invertebrate herbivores and predators to illumination at night over a three‐year period to simulate conditions under different common forms of street lighting.3.We demonstrate both top‐down (predation controlled) and bottom‐up (resource controlled) impacts of artificial light at night in grassland communities. The impacts on invertebrate herbivore abundance were wavelength dependent and mediated via other trophic levels.4.White LED lighting decreased the abundance of a generalist herbivore mollusc by 55% in the presence of a visual predator, but not in its absence, while monochromatic amber light (with a peak wavelength similar to low pressure sodium lighting) decreased abundance of a specialist herbivore aphid (by 17%) by reducing the cover and flower abundance of its main food plant in the system. Artificial white light also significantly increased the food plant's foliar carbon to nitrogen ratio.5.We conclude that exposure to artificial light at night can trigger ecological effects spanning trophic levels, and that the nature of such impacts depends on the wavelengths emitted by the lighting technology employed.6.Policy implications. Our results confirm that artificial light at night, at illuminance levels similar to roadside vegetation, can have population effects mediated by both top‐down and bottom‐up effects on ecosystems. Given the increasing ubiquity of light pollution at night, these impacts may be widespread in the environment. These results underline the importance of minimising ecosystem disruption by reducing light pollution in natural and semi‐natural ecosystems.

AB - 1.Globally, many ecosystems are exposed to artificial light at night. Nighttime lighting has direct biological impacts on species at all trophic levels. However, the effects of artificial light on biotic interactions remain, for the most part, to be determined.2.We exposed experimental mesocosms containing combinations of grassland plants and invertebrate herbivores and predators to illumination at night over a three‐year period to simulate conditions under different common forms of street lighting.3.We demonstrate both top‐down (predation controlled) and bottom‐up (resource controlled) impacts of artificial light at night in grassland communities. The impacts on invertebrate herbivore abundance were wavelength dependent and mediated via other trophic levels.4.White LED lighting decreased the abundance of a generalist herbivore mollusc by 55% in the presence of a visual predator, but not in its absence, while monochromatic amber light (with a peak wavelength similar to low pressure sodium lighting) decreased abundance of a specialist herbivore aphid (by 17%) by reducing the cover and flower abundance of its main food plant in the system. Artificial white light also significantly increased the food plant's foliar carbon to nitrogen ratio.5.We conclude that exposure to artificial light at night can trigger ecological effects spanning trophic levels, and that the nature of such impacts depends on the wavelengths emitted by the lighting technology employed.6.Policy implications. Our results confirm that artificial light at night, at illuminance levels similar to roadside vegetation, can have population effects mediated by both top‐down and bottom‐up effects on ecosystems. Given the increasing ubiquity of light pollution at night, these impacts may be widespread in the environment. These results underline the importance of minimising ecosystem disruption by reducing light pollution in natural and semi‐natural ecosystems.

KW - Light pollution

KW - Photopollution

KW - Grasslands

KW - Trophic levels

KW - Aphids

KW - Molluscs

KW - artificial light

KW - street lights

UR - https://besjournals.onlinelibrary.wiley.com/action/downloadSupplement?doi=10.1111%2F1365-2664.13240&file=jpe13240-sup-0001-SupInfo.docx

U2 - 10.1111/1365-2664.13240

DO - 10.1111/1365-2664.13240

M3 - Article

VL - 55

SP - 2698

EP - 2706

JO - Journal of Applied Ecology

JF - Journal of Applied Ecology

SN - 1365-2664

IS - 6

ER -