Artificial light at night alters trophic interactions of intertidal invertebrates

Abstract

Despite being globally widespread in coastal regions, the impacts of light pollution on intertidal ecosystems has received little attention. Intertidal species exhibit many night-time-dependent ecological strategies, including feeding, reproduction, orientation and predator avoidance, which are likely negatively affected by shifting light regimes, as has been observed in terrestrial and aquatic taxa. Coastal lighting may shape intertidal communities through its influence on the nocturnal foraging activity of dogwhelks (Nucella lapillus), a widespread predatory mollusc that structures biodiversity in temperate rocky shores. In the laboratory, we investigated whether the basal and foraging activity of this predator was affected by exposure to night-time lighting both in the presence and absence of olfactory predator cues (Carcinus maenas, common shore crab). Assessments of dogwhelks' behavioural responses to night-time white LED lighting were performed on individuals that had been acclimated to night-time white LED lighting conditions for 16 days and individuals that had not previously been exposed to artificial light at night. Dogwhelks acclimated to night-time lighting exhibited natural refuge-seeking behaviour less often compared to control animals, but were more likely to respond to and handle prey irrespective of whether olfactory predator cues were present. These responses suggest night-time lighting likely increased the energetic demand of dogwhelks through stress, encouraging foraging whenever food was available, regardless of potential danger. Contrastingly, whelks not acclimated under night-time lighting were more likely to respond to the presence of prey under artificial light at night when olfactory predator cues were present, indicating an opportunistic shift towards the use of visual instead of olfactory cues in risk evaluation. These results demonstrate that artificial night-time lighting influences the behaviour of intertidal fauna such that the balance of interspecific interactions involved in community structuring may be affected.

Trophic compensation stabilizes marine primary producers exposed to artificial light at night

“…Knowledge of biological and ecological effects of ALAN is rapidly growing, but impacts on marine coastal ecosystems are still underexplored. Recent studies revealed effects on predator− prey interactions including invertebrates and fish, due to influences on their behavior (Bolton et al 2017, Underwood et al 2017. Here, we report the first evidence of alteration in herbivore−resource relationships in marine assemblages, due to direct and indirect effects of ALAN .…”

“…By disrupting natural light/dark cycles, ALAN is expected to influence primary producers either directly (through photosynthetic activity and cell growth; see Jacquet et al 2001) or indirectly through its effect on grazing pressure. Here, we provide an experimental test of these hypotheses by manipulating nighttime artificial lighting and gastropod grazers in a rocky intertidal food web, where microphytobenthos (MPB) covering rock surfaces represents the main fraction of biomass produced and a key food resource for grazers (Underwood et al 2017).…”

Emerging threat of the 21st century lightscape to global biodiversity

“…Artificial lights increased prey intake by several species of wading shorebirds, which could result in longer term depletion of local invertebrate densities (Santos et al, 2010). Similarly, artificial lighting influenced the foraging behavior of the dogwhelk (Nucella lapillus), a predatory mollusk, with potential cascading effects on the community structure of intertidal fauna (Underwood, Davies, & Queir os, 2017). Artificial light had a varied effect on prey consumption by a community of insectivorous bat species, whereby several bat species showed an increased consumption of their preferred prey type (Cravens, Brown, Divoll, & Boyles, 2018).…”

How dark is a river? Artificial light at night in aquatic systems and the need for comprehensive night‐time light measurements

“…Because ALAN is linked closely to human activity (Elvidge et al, ), it is assumed to affect freshwater systems and coastal areas disproportionally (Zhao, Li, Li, Zhao, & Wu, ). The effects of ALAN on aquatic organisms and communities have been researched in several laboratory (Brüning, Hölker, Franke, Kleiner, & Kloas, ; Brüning, Hölker, Franke, Preuer, & Kloas, ; Hölker et al, ; Kurvers et al, ; Perkin, Hölker, Heller, & Berghahn, ; Poulin et al, ; Szekeres et al, ) and field studies (Becker, Whitfield, Cowley, Järnegren, & Næsje, ; Bolton et al, ; Brüning, Kloas, Preuer, & Hölker, ; Cullen & McCarthy, ; Davies, Duffy, Bennie, & Gaston, ; Grubisic et al, ; Grubisic, van Grunsven, Manfrin, Monaghan, & Hölker, ; Hölker et al, ; Ludvigsen et al, ; Manfrin et al, , ; Meyer & Sullivan, ; Moore, Pierce, Walsh, Kvalvik, & Lim, ; Perkin, Hölker, & Tockner, ; Perkin, Hölker, Tockner, & Richardson, ; Riley, Bendall, Ives, Edmonds, & Maxwell, ; Riley, Davison, Maxwell, & Bendall, ; Szaz et al, ; Tabor, Brown, & Luiting, ; Underwood, Davies, & Queirós, ). However, we found a knowledge gap regarding the status quo of light pollution in and along aquatic systems.…”