Artificial light at night at the terrestrial-aquatic interface: Effects on predators and fluxes of insect prey

Abstract

The outcomes of species interactions-such as those between predators and prey-increasingly depend on environmental conditions that are modified by human activities. Light is among the most fundamental environmental parameters, and humans have dramatically altered natural light regimes across much of the globe through the addition of artificial light at night (ALAN). The consequences for species interactions, communities and ecosystems are just beginning to be understood. Here we present findings from a replicated field experiment that simulated over-the-water lighting in the littoral zone of a small lake. We evaluated responses by emergent aquatic insects and terrestrial invertebrate communities, and riparian predators (tetragnathid spiders). On average ALAN plots had 51% more spiders than control plots that were not illuminated. Mean individual spider body mass was greater in ALAN plots relative to controls, an effect that was strongly sex-dependent; mean male body mass was 34% greater in ALAN plots while female body mass was 176% greater. The average number of prey items captured in spider webs was 139% greater on ALAN mesocosms, an effect attributed to emergent aquatic insects. Non-metric multidimensional scaling and a multiple response permutation procedure revealed significantly different invertebrate communities captured in pan traps positioned in ALAN plots and controls. Control plots had taxonomic-diversity values (as H') that were 58% greater than ALAN plots, and communities that were 83% more-even. We attribute these differences to the aquatic family Caenidae which was the dominant family across both light treatments, but was 818% more abundant in ALAN plots. Our findings show that when ALAN is located in close proximity to freshwater it can concentrate fluxes of emergent aquatic insects, and that terrestrial predators in the littoral zone can compound this effect and intercept resource flows, preventing them from entering the terrestrial realm.

Light pollution: A landscape-scale issue requiring cross-realm consideration

“…The consequences of these effects of ALAN depend on the time-scale considered and may be sex-specific. For example, short-term (two-month) exposure to ALAN increased the abundance and body mass of riparian long-jawed orb weavers (family Tetragnathidae) (Parkinson et al 2020). These effects were more pronounced for females compared to males and were concordant with greater numbers of prey items captured in spider webs under ALAN compared to webs under natural night-time conditions.…”

“…Together, these studies suggest that aggregation of predators and prey around ALAN can increase predation on emerging aquatic insects and so reduce the transfer of biomass from aquatic to terrestrial systems through riparian zones. Concurrently, this would shift biomass from dark areas into artificially illuminated areas and dramatically shift the distribution, overall abundance, and diversity of insect communities reducing their abundance as prey (Perkin et al 2014, Parkinson et al 2020. Therefore, by altering both the abundance and predation success of terrestrial predators, as well as the distribution and abundance of aquatic prey, ALAN can drive shifts in predator-prey interactions across realm boundaries, altering flows of energy between aquatic and terrestrial systems, with important consequences for both realms.…”

Artificial Light Pollution with Different Wavelengths at Night Interferes with Development, Reproduction, and Antipredator Defenses of Daphnia magna

“…As demonstrated in some studies, ALAN is assumed to alter natural light regimes in aquatic ecosystems and can affect light-sensitive processes and behaviors of aquatic organisms. ,− ALAN can also change the predator–prey interactions, , which is the main evolutionary driving force to regulate the behavior of predators and prey. , The distribution of ALAN has complex effects on the predator–prey relationship and richness. For example, brighter nights increase the gathering of small fishes and further attract the large piscivorous fish because of the increased foraging opportunities at night. , For prey, antipredation strategies must be in place to detect predation risks and take quick evasive actions to avoid being caught.…”

The Influence of Artificial Light at Night on Asthma and Allergy, Mental Health, and Cancer Outcomes: A Systematic Scoping Review Protocol

“…Although artificial light has made our nights more enjoyable and productive, it has also imparted a tremendous adverse effect on the ecosystem at large [ 3 , 4 ]. Light pollution has become a serious environmental concern as artificial light at night (ALAN) severely disrupts the biological cycles of plants, insects, and nocturnal animals by altering their circadian rhythms [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ]. ALAN exposure comes from many sources, with indoor light being the most prominent.…”