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Garratt, M. J., Jenkins, S. R., & Davies, T. W. (2019). Mapping the consequences of artificial light at night for intertidal ecosystems. Science of The Total Environment, in press.
Abstract: Widespread coastal urbanization has resulted in artificial light pollution encroaching into intertidal habitats, which are highly valued by society for ecosystem services including coastal protection, climate regulation and recreation. While the impacts of artificial light at night in terrestrial and riparian ecosystems are increasingly well documented, those on organisms that reside in coastal intertidal habitats are less well explored. The distribution of artificial light at night from seaside promenade lighting was mapped across a sandy shore, and its consequences for macroinvertebrate community structure quantified accounting for other collinear environmental variables known to shape biodiversity in intertidal ecosystems (shore height, wave exposure and organic matter content). Macroinvertebrate community composition significantly changed along artificial light gradients. Greater numbers of species and total community biomass were observed with increasing illumination, a relationship that was more pronounced (increased effects size) with increasing organic matter availability. Individual taxa exhibited different relationships with artificial light illuminance; the abundances of 27% of non-rare taxa [including amphipods (Amphipoda), catworms (Nephtys spp.), and sand mason worms (Lanice conchilega)] decreased with increasing illumination, while 20% [including tellins (Tellinidae spp.), lugworms (Arenicola marina) and ragworms (Nereididae spp.)] increased. Possible causes of these relationships are discussed, including direct effects of artificial light on macroinvertebrate behaviour and indirect effects via trophic interactions. With increasing light pollution in coastal zones around the world, larger scale changes in intertidal ecosystems could be occurring.
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Bowden, J. (1982). An Analysis of Factors Affecting Catches of Insects in Light-Traps. Bull. Entomol. Res., 72(4), 535–556.
Abstract: Analysis of published data on catches of insects in light-traps with a variety of light sources and of different designs showed that all conformed to the previously proposed model describing the functioning of a light-trap: catch = constant × where W = trap illumination and I = background illumination. Light-trap catches in differing cloud conditions and in open and woodland situations also varied as predicted by the model. A table of correction factors for different amounts of cloud cover is provided. The results are discussed in relation to use of light-traps and interpretation of light-trap data.
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Merckx, T., Van Dyck, H., & Isaac, N. (2019). Urbanization‐driven homogenization is more pronounced and happens at wider spatial scales in nocturnal and mobile flying insects. Global Ecol Biogeogr, in press.
Abstract: Aim
We test whether urbanization drives biotic homogenization. We hypothesize that declines in abundance and species diversity of aerial insects are exacerbated by the urbanization‐driven loss of species with low habitat generalism, mobility and warm‐adaptedness. We predict this homogenization to be more pronounced for nocturnal taxa, and at wider scales for mobile taxa.
Location
Belgium.
Time period
Summers 2014–2015.
Major taxa studied
Lepidoptera.
Methods
We compare communities along urbanization gradients using a shared, replicated and nested sampling design, in which butterflies were counted within 81 grassland and macro‐moths light‐trapped in 12 woodland sites. We quantify taxonomic and functional community composition, the latter via community‐weighted means and variation of species‐specific traits related to specialization, mobility and thermophily. Using linear regression models, variables are analysed in relation to site‐specific urbanization values quantified at seven scales (50–3,200 m radii). At best‐fitting scales, we test for taxonomic homogenization.
Results
With increasing urbanization, abundance, species richness and Shannon diversity severely declined, with butterfly and macro‐moth declines due to local‐ versus landscape‐scale urbanization (200 vs. 800–3,200 m radii, respectively). While taxonomic homogenization was absent for butterflies, urban macro‐moth communities displayed higher nestedness than non‐urban communities. Overall, communities showed mean shifts towards generalist, mobile and thermophilous species, displaying trait convergence too. These functional trait models consistently fit best with urbanization quantified at local scales (100–200 m radii) for butterfly communities, and at local to wider landscape scales (200–800 m radii) for macro‐moth communities.
Main conclusions
Urban communities display functional homogenization that follows urbanization at scales linked to taxon‐specific mobility. Light pollution may explain why homogenization was more pronounced for the nocturnal taxon. We discuss that urbanization is likely to impact flying insect communities across the globe, but also that impacts on their ecosystem functions and services could be mitigated via multi‐scale implementation of urban green infrastructure.
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Li, X., Duarte, F., & Ratti, C. (2019). Analyzing the obstruction effects of obstacles on light pollution caused by street lighting system in Cambridge, Massachusetts. Environment and Planning B: Urban Analytics and City Science, in press.
Abstract: Artificial light has transformed urban life, enhancing visibility, aesthetics, and increasing safety in public areas. However, too much unwanted artificial light leads to light pollution, which has a negative effect on public health and urban ecosystems, as well as on the aesthetic and cultural meanings of the night sky. Some of the factors interfering with the estimation of light pollution in cities are urban features, such as the presence of trees, road dimensions, and the physical characteristics of buildings. In this study, we proposed a simplified model for unwanted upward light coming from street luminaires based on a building height model and the publicly accessible Google Street View images. We simulated and analyzed the obstruction effects of different street features on the light pollution caused by the street lighting system in Cambridge, Massachusetts. By providing quantitative information about the connections between the streetscape features and the amount of unwanted upward artificial light, this study provides reference values to inform policies aimed at curbing light pollution.
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Maggio, R., Vaglini, F., Rossi, M., Fasciani, I., Pietrantoni, I., Marampon, F., et al. (2019). Parkinson's disease and light: The bright and the Dark sides. Brain Res Bull, 150, 290–296.
Abstract: Light exerts a major influence on human behaviour and health, mainly owing to the importance of sight in our lives, but also due to its entrainment of daily rhythms via the suprachiasmatic nucleus, the master pacemaker. Light may also be a useful clinical medium, as in lumino-therapy for the improvement of depressed mood. Further, as discussed herein, local application of near infrared light to the substantia nigra exerts neuroprotective properties in models of Parkinson's disease. However, light also has a darker side. In general, as regards the growing problem to human health – and the natural world – of excess exposure to artificial light: both urban glow and ubiquitous screens. Moreover, over-exposure to light, in particular fluorescent light, disrupts circadian rhythms and sleep, and may damage dopaminergic neurons. Is it, then, a neglected risk factor for Parkinson's disease? The present article discusses epidemiological and experimental evidence supporting beneficial and potentially deleterious impact of light on dopaminergic neurons and highlights the mechanisms whereby light might influence neuronal tissue.
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