How ecological communities respond to artificial light at night

Abstract

Many ecosystems worldwide are exposed to artificial light at night (ALAN), from streetlights and other sources, and a wide range of organisms has been shown to respond to this anthropogenic pressure. This raises concerns about the consequences for major ecosystem functions and their stability. However, there is limited understanding of how whole ecological communities respond to ALAN, and this cannot be gained simply by making predictions from observed single species physiological, behavioral, or ecological responses. Research needs to include an important building block of ecological communities, namely the interactions between species that drive ecological and evolutionary processes in ecosystems. Here, we summarize current knowledge about community responses to ALAN and illustrate different pathways and their impact on ecosystem functioning and stability. We discuss that documentation of the impact of ALAN on species interaction networks and trait distributions provides useful tools to link changes in community structure to ecosystem functions. Finally, we suggest several approaches to advance research that will link the diverse impact of ALAN to changes in ecosystems.

Keywords: ecosystem functioning; interaction networks; light pollution; species interactions; stability; traits.

Figure 1

Linking ALAN impact to the stability and functioning of ecological communities. ALAN can act as an environmental filter through a change in animal movement (attraction, avoidance) and behavior or survival thereby influencing community assembly. It can also change communities by changing species’ realized niches and interactions between species. ALAN can increase or decrease interaction strength or lead to new interactions or the extinction of former interactions, thereby changing the structure of interaction networks. A change in community structure can lead to a change in the distribution of traits in communities such as body size or trophic niche. Therefore a major impact of ALAN on function and stability will be through a change in the distribution of species traits and the structure of the interaction network [Color figure can be viewed at http://wileyonlinelibrary.com]

Figure 2

Impact of ALAN on (A) species (nodes) and (B) interactions (links) and different scenarios for different parts in a food web/network affected: (A) single species, (B) single interactions, (C) single trophic levels, (D) interaction between two trophic levels, (E) the whole food web, or (F) a food web or network compartment

Figure 3

Trait analysis for ecological communities can help to explain their response to ALAN as an environmental factor and how changes in the community are related to changes in ecosystem functions [Color figure can be viewed at http://wileyonlinelibrary.com]