Consequences of artificial light at night on behavior, reproduction, and development of Lymnaea stagnalis

The Molluscicidal Activity of Green Synthesized Copper Oxide-Based Annona squamosa Seed Extract Nanoparticles on the Feeding Behavior, Biochemical, Molecular, and Immunohistochemical Alterations of Biomphalaria alexandrina Snails

Because of their low ecological impact, plant molluscicides have garnered much attention. The work aimed to find out if Annona squamosa (AS) seed extract has a molluscicidal impact on Biomphalaria alexandrina snails and enhances this extract by adding CuO nanoparticles (NPs). Using a scanning electron microscope (SEM), transmission electron microscope (TEM), and PANalytical X'Pert PRO X-ray diffractometer (XRD), the presence of the green A. squamosa-based CuO NPs (AS-CuO NPs) was confirmed. After 24 h of exposure, the half-lethal concentration (LC50) of AS-CuO NPs was more toxic to mature B. alexandrina than the aqueous extract of AS seeds (LC50: 119.25 mg/L vs. 169.03 mg/L). The results show that snails exposed to sublethal doses of AS-CuO NPs at LC10 or LC25 (95.4 or 106.7 mg/L, respectively) had much higher glucose levels and alkaline phosphatase activity than those not exposed. Nevertheless, there was no discernible change in the protein content in general or glycogen phosphorylase production. Histological and immunohistochemical analysis showed that snails exposed to A. squamosa-derived CuO NPs LC10 had shrinking digestive tubules and degeneration as well as vacuolation of many digestive, secretory, ova, and sperm cells, with PCNA expressing positively in the hermaphrodite gland and digestive tubule cells. The toxic profile of green CuO NPs produced by A. squamosa may damage the biological activity of B. alexandrina snails; thus, this compound could be used as a molluscicidal base. Furthermore, B. alexandrina proved to be a useful biomarker of nanomaterial contamination.

Better, not more, lighting: Policies in urban areas towards environmentally-sound illumination of historical stone buildings that also halts biological colonization

Anthropogenic or Artificial light at night (ALAN) pollution, or more simply light pollution, is an issue of increasing concern to the general public, as well as to scientists and politicians. However, although advances have been made in terms of scientific knowledge, these advances have not been fully transferred to or considered by politicians. In addition, illumination of stone monuments in urban areas is an emerging contribution to ALAN pollution that has scarcely been considered to date. This paper presents a literature review of the topic of light pollution and related policies, including a bibliometric analysis of studies published between 2020 and 2022. The prevailing legislation in Europe regarding the regulation of outdoor lighting, which emphasises the complexity of controlling light pollution, is summarised and the regulation of monumental lighting in Spain is discussed. Findings concerning the impact of ALAN on biodiversity in urban areas, and the promising biostatic effect of ornamental lighting (halting biological colonization on stone monuments, mainly caused by algae and cyanobacteria) are described. Finally, trends in monument illumination and policymaking towards environmentally sustainable management are considered.

A framework for untangling the consequences of artificial light at night on species interactions

Although much evidence exists showing organismal consequences from artificial light at night (ALAN), large knowledge gaps remain regarding ALAN affecting species interactions. Species interactions occur via shared spatio-temporal niches among species, which may be determined by natural light levels. We review how ALAN is altering these spatio-temporal niches through expanding twilight or full Moon conditions and constricting nocturnal conditions as well as creating patches of bright and dark. We review literature from a database to determine if ALAN is affecting species interactions via spatio-temporal dynamics. The literature indicates a growing interest in ALAN and species interactions: 58% of the studies we analysed have been published since 2020. Seventy-five of 79 studies found ALAN altered species interactions. Enhancements and reductions of species interactions were equally documented. Many studies revealed ALAN affecting species interactions spatially, but few revealed temporal alterations. There are biases regarding species interactions and ALAN-most studies investigated predator-prey interactions with vertebrates as predators and invertebrates as prey. Following this literature review, we suggest avenues, such as remote sensing and animal tracking, that can guide future research on the consequences of ALAN on species interactions across spatial and temporal axes. This article is part of the theme issue 'Light pollution in complex ecological systems'.

Light pollution of freshwater ecosystems: principles, ecological impacts and remedies

Light pollution caused by artificial light at night (ALAN) is increasingly recognized as a major driver of global environmental change. Since emissions are rapidly growing in an urbanizing world and half of the human population lives close to a freshwater shoreline, rivers and lakes are ever more exposed to light pollution worldwide. However, although light conditions are critical to aquatic species, and freshwaters are biodiversity hotspots and vital to human well-being, only a small fraction of studies conducted on ALAN focus on these ecosystems. The effects of light pollution on freshwaters are broad and concern all levels of biodiversity. Experiments have demonstrated diverse behavioural and physiological responses of species, even at low light levels. Prominent examples are skyglow effects on diel vertical migration of zooplankton and the suppression of melatonin production in fish. However, responses vary widely among taxa, suggesting consequences for species distribution patterns, potential to create novel communities across ecosystem boundaries, and cascading effects on ecosystem functioning. Understanding, predicting and alleviating the ecological impacts of light pollution on freshwaters requires a solid consideration of the physical properties of light propagating in water and a multitude of biological responses. This knowledge is urgently needed to develop innovative lighting concepts, mitigation strategies and specifically targeted measures. This article is part of the theme issue 'Light pollution in complex ecological systems'.

Impacts of artificial light at night on the early life history of two ecosystem engineers

Sessile marine invertebrates play a vital role as ecosystem engineers and in benthic-pelagic coupling. Most benthic fauna develop through larval stages and the importance of natural light cycles for larval biology and ecology is long-established. Natural light-dark cycles regulate two of the largest ocean-scale processes that are fundamental to larvae's life cycle: the timing of broadcast spawning for successful fertilization and diel vertical migration for foraging and predator avoidance. Given the reliance on light and the ecological role of larvae, surprisingly little is known about the impacts of artificial light at night (ALAN) on the early life history of habitat-forming species. We quantified ALAN impacts on larval performance (survival, growth, development) of two cosmopolitan ecosystem engineers in temperate marine ecosystems, the mussel Mytilus edulis and the barnacle Austrominius modestus. Higher ALAN irradiance reduced survival in both species (57% and 13%, respectively). ALAN effects on development and growth were small overall, and different between species, time-points and parentage. Our results show that ALAN adversely affects larval survival and reiterates the importance of paternal influence on offspring performance. ALAN impacts on the early life stages of ecosystem engineering species have implications not only for population viability but also the ecological communities that these species support. This article is part of the theme issue 'Light pollution in complex ecological systems'.

Intense Locomotion Enhances Oviposition in the Freshwater Mollusc Lymnaea stagnalis: Cellular and Molecular Correlates

Intense species-specific locomotion changes the behavioural and cognitive states of various vertebrates and invertebrates. However, whether and how reproductive behaviour is affected by previous increased motor activity remains largely unknown. We addressed this question using a model organism, the pond snail Lymnaea stagnalis. Intense crawling in shallow water for two hours had previously been shown to affect orienting behaviour in a new environment as well as the state of the serotonergic system in L. stagnalis. We found that the same behaviour resulted in an increased number of egg clutches and the total number of eggs laid in the following 24 h. However, the number of eggs per clutch was not affected. This effect was significantly stronger from January to May, in contrast to the September-December period. Transcripts of the egg-laying prohormone gene and the tryptophan hydroxylase gene, which codes for the rate-limiting enzyme in serotonin synthesis, were significantly higher in the central nervous system of snails that rested in clean water for two hours after intense crawling. Additionally, the neurons of the left (but not the right) caudo-dorsal cluster (CDC), which produce the ovulation hormone and play a key role in oviposition, responded to stimulation with a higher number of spikes, although there were no differences in their resting membrane potentials. We speculate that the left-right asymmetry of the response was due to the asymmetric (right) location of the male reproductive neurons having an antagonistic influence on the female hormonal system in the hermaphrodite mollusc. Serotonin, which is known to enhance oviposition in L. stagnalis, had no direct effect on the membrane potential or electrical activity of CDC neurons. Our data suggest that (i) two-hour crawling in shallow water enhances oviposition in L. stagnalis, (ii) the effect depends on the season, and (iii) the underlying mechanisms may include increased excitability of the CDC neurons and increased expression of the egg-laying prohormone gene.

A review of the effects of artificial light at night in urban areas on the ecosystem level and the remedial measures

This paper attempts to realize the balance between humans and ecology in designing the nighttime light environment of urban parks by clarifying the influence of nighttime artificial light on the ecosystem of urban parks. Firstly, we reviewed the effects of nighttime artificial light on individual predation and reproduction of animals and personal growth and reproduction of plants. Secondly, we discuss the impact of individual changes caused by artificial lighting on ecosystem function at the ecosystem and analyze its advantages and disadvantages. The results showed that nighttime artificial light had a double-sided impact on the ecosystem, which would hurt the ecosystem function, but had a positive effect on the green space, which lacked natural light and had high plant density. This paper focuses on the areas with increased application of artificial lighting and rich species of animals and plants in night cities, such as urban forest parks and urban green spaces. It discusses how to reduce the intrusion of artificial lighting on ecosystems and how to make better use of the positive effect of artificial light.

Casting a light on the shoreline: The influence of light pollution on intertidal settings

Light pollution is becoming prevalent among other coastal stressors, particularly along intertidal habitats, arguably the most exposed to anthropogenic light sources. As the number of light pollution studies on sandy beaches, rocky shores and other intertidal habitats raises, commonalities, research gaps and venues can be identified. Hence, the influence of light pollution on the behavior and ecology of a variety of intertidal macro-invertebrates and vertebrates are outlined by examining 54 published studies. To date, a large majority of the reported effects of light pollution are negative, as expected from the analysis of many species with circadian rhythms or nocturnal habits, although the severity of those effects ranges widely. Experimental approaches are well represented throughout but methodological limitations in measurement units and standardization continue to limit the proposal of general conclusions across species and habitats. In addition, studies targeting community variables and the explicit influence of skyglow are heavily underrepresented. Likewise, studies addressing the interaction between light pollution and other natural and anthropogenic stressors are critically needed and represent a key venue of research. The nature of those interactions (synergistic, additive, antagonistic) will likely dictate the impact and management of light pollution in the decades ahead.