Artificial Lighting at Night in Estuaries—Implications from Individuals to Ecosystems

Abstract

Artificial lighting at night (ALAN) produced by urban, industrial, and roadway lighting, as well as other sources, has dramatically increased in recent decades, especially in coastal environments that support dense human populations. Artificial Blightscapes^are characterized by distinct spatial, temporal, and spectral patterns that can alter natural patterns of light and dark with consequences across levels of biological organization. At the individual level, ALAN can elicit a suite of physiological and behavioral responses associated with light-mediated processes such as diel activity patterns and predator-prey interactions. ALAN has also been shown to modify community composition and trophic structure, with implications for ecosystem-level processes including primary productivity, nutrient cycling, and the energetic linkages between aquatic and terrestrial systems. Here, we review the state of the science relative to the impacts of ALAN on estuaries, which is an important step in assessing the long-term sustainability of coastal regions. We first consider how multiple properties of ALAN (e.g., intensity and spectral content) influence the interaction between physiology and behavior of individual estuarine biota (drawing from studies on invertebrates, fishes, and birds). Second, we link individual-to community-and ecosystem-level responses, with a focus on the impacts of ALAN on food webs and implications for estuarine ecosystem functions. Coastal aquatic communities and ecosystems have been identified as a key priority for ALAN research, and a cohesive research framework will be critical for understanding and mitigating ecological consequences.

Combined salinity and acidity stressors alterDaphnia magnapopulation growth and structure under severe absence of photoperiod

“…The fourth is an under-examined side effect of constant light exposure on the onset of increased Daphnia reproduction under certain levels of salinity and/or acidity stress that are considered otherwise unfavourable for exponential reproduction. Light pollution effects, in terms of artificial light, sky glow and interference with daylight-night-time patterns, which increasingly affect aquatic ecosystems and ecological interactions [34,106], are becoming a serious concern associated with urbanisation and industrialised zones with increasing human population around the globe [30,34,107–110]. The far-reaching effects of extended light exposure [34] may not only lead to changes in vital phototactic behaviours with disruptive impacts on the aquatic system [30,34], but may also extend to how zooplankton respond to a cocktail of stressors [77,111].…”

“…Meyer & Sullivan (2013) demonstrated that ecological light pollution through increased night lighting modifies community composition, structure, and characteristics and thus ecosystem functioning via alteration of nutrient exchange and aquatic–terrestrial fluxes of invertebrates [32]. These altered fluxes may have cascading effects through riparian and aquatic food webs [33,34]. However, although a number of studies endeavoured to shed light on the effects of darkness and light at night on the physiology, behaviour, growth and development, and fitness of a range of aquatic organisms [34–36], the effect of lack of photoperiod, on daphnid phenotype, fitness and survival is surprisingly poorly studied.…”

“…These altered fluxes may have cascading effects through riparian and aquatic food webs [33,34]. However, although a number of studies endeavoured to shed light on the effects of darkness and light at night on the physiology, behaviour, growth and development, and fitness of a range of aquatic organisms [34–36], the effect of lack of photoperiod, on daphnid phenotype, fitness and survival is surprisingly poorly studied. To date, very little is known about those effects on zooplankton [30,37] and their implications for ecosystems subject to light pollution which are simultaneously vulnerable to salinisation and acidification.…”

“…These patterns and types of complex physico-chemical stress are predicted to lead to a reduction in biodiversity, especially when accompanied by upsetting the thermal regimes in aquatic and freshwater ecosystems because of climate change and environment modification ( e.g. , arboreal and riparian vegetation alteration) by humans [34,44,45]. There is a significant gap in current knowledge about how the genotype of organisms in general, and zooplankton of economic importance in particular, would respond, in terms of reproductions and development, to the absence of photoperiod, let alone the combination of such physical stress with composite chemical stress (salinisation and acidification of water).…”

Artificial Light at Night as a New Threat for Nature Conservation in Ukraine

“…For example, light pollution can cause cascading eff ects in habitats, restructuring ecological communities by modifying the interactions between species and impacting pollination and seed dispersal . As well ALAN implications in estuaries from individuals to habitats (Zapata et al, 2019) as well as in stream and riparian habitats (Manfrin et al, 2018;Perkin et al, 2011) have been analised.…”