Artificial Light at Night Alleviates the Negative Effect of Pb on Freshwater Ecosystems

Abstract

Artificial light at night (ALAN) is an increasing phenomenon worldwide that can cause a series of biological and ecological effects, yet little is known about its potential interaction with other stressors in aquatic ecosystems. Here, we tested whether the impact of lead (Pb) on litter decomposition was altered by ALAN exposure using an indoor microcosm experiment. The results showed that ALAN exposure alone significantly increased leaf litter decomposition, decreased the lignin content of leaf litter, and altered fungal community composition and structure. The decomposition rate was 51% higher in Pb with ALAN exposure treatments than in Pb without ALAN treatments, resulting in increased microbial biomass, β-glucosidase (β-G) activity, and the enhanced correlation between β-G and litter decomposition rate. These results indicate that the negative effect of Pb on leaf litter decomposition in aquatic ecosystems may be alleviated by ALAN. In addition, ALAN exposure also alters the correlation among fungi associated with leaf litter decomposition. In summary, this study expands our understanding of Pb toxicity on litter decomposition in freshwater ecosystems and highlights the importance of considering ALAN when assessing environmental metal pollutions.

Light Pollution Changes the Toxicological Effects of Cadmium on Microbial Community Structure and Function Associated with Leaf Litter Decomposition

“…This finding supported the hypothesis that the biological characteristics of the altered microbial community facilitated the ability of the community to cope with Cd toxicity [3]. Interestingly, this is consistent with previous findings that leaf litter decomposition related fungi could form adaptive mechanisms for tolerance to NPs and/or metal ions (e.g., ZnONP, AgNP, and Cu 2+ ) by accumulating dominant species [3,10,28,29].…”

“…These results indicated that ALAN exposure can alter the fungal community structure and composition. This is consistent with the results of recent studies which showed that light radiation not only can alter the fungal community, but also inhibit litter decomposition associated with fungi [8][9][10]. However, our results differ from these studies [8,9] in that effects of different light conditions on the structure and diversity of fungal communities are significantly different.…”

“…Hence, the fungal community can be used as an indicator to evaluate the response to environmental stress [24]. Previous studies showed that light (UV radiation or ALAN) cannot only increase the degradation of complex aromatic compounds [25], but also alter microbial communities [5,[8][9][10]. Our results showed that ALAN exposure always decreased unique fungal OTUs and altered the abundance of the six most abundant genera (Figure 1a,b).…”

“…Some recent studies also showed that excessive light (24 h/day) exposure can enhance the inhibitory 2 of 13 effect of nanoZnO on explaining light-induced dissolution of nanoZnO [8,9]. Our recent studies have shown that ALAN could not only alleviate the negative effects of silver nanoparticles (AgNP) or Pb on plant litter decomposition in streams but also affect the fungal community composition and function associated with litter decomposition [10,13]. Despite our increasing understanding of the interaction effects of ALAN and chemical pollutants on plant litter decomposition, we still know little about the mechanisms by which microbes adjust their community composition and function in response to ALAN.…”

“…In freshwater ecosystems, there are more and more emerging pollutants, such as artificial light at night (ALAN, also known as light pollution) because of ongoing anthropogenic activities, especially near the streams there is a high concentration of people [4]. Many studies have indicated that ALAN can not only directly affect a very wide diversity of species including plants, animals, and microbes [4][5][6][7], but also indirectly affect other chemical pollutants by changing their states and associated environmental factors [5,[8][9][10]. Interactional effects between natural stressors (temperature, oxygen consumption, and heat) and toxicants (heavy metals and polycyclic aromatic hydrocarbons) have been studied [11,12].…”