Artificial light as a driver of nighttime landscape ecology

Lead Research Organisation: University of Exeter
Department Name: Biosciences

Abstract

Artificial light, from streetlights and other sources, is eroding natural light cycles over large areas of the globe; more than 80% of people now live under light polluted skies. Artificial light is thus giving rise to an environmental pressure on organisms that they have not previously encountered in their evolutionary histories. Documented impacts include effects on the physiology and behaviour of individual organisms, the abundance and distribution of species, and the structure and functioning of ecological communities. However, the exposure of organisms to artificial light in real landscapes, and thus the spatial extent and temporal dynamics of these effects, remain poorly understood. In major part this is because there is a substantial mismatch between the relatively coarse spatial and temporal scales at which artificial light has to date typically been mapped (often using satellites) and the relatively fine spatial and temporal scales at which organisms will often experience artificial nighttime lighting. This lack of detail constrains understanding of how animals move within, and respond to, dynamic lightscapes. In this project we will address this important limitation. We will measure the spatial and temporal distributions of artificial nighttime lighting across urban and suburban sites, and use these data to build generalisable models of their light dynamics. We will then produce high resolution maps that more accurately represent the ecological barriers, fragmentation and patch structure of light in urban and suburban areas and test these with new ecological data on the movements of hedgehogs, bats and moths. Only once ecological risks of artificial light at night have been understood at relevant spatial and temporal scales can better mitigation strategies be implemented to alleviate pressure from this pernicious driver of global change.

Planned Impact

There has been increasing public and policy debate around the negative impacts of artificial lighting of the nighttime environment (including on views of the natural nighttime sky, on the natural environment, and on human health), and how best to limit these whilst delivering the substantial (actual and perceived) human benefits that such lighting can provide. However, discussion of these issues has often been framed in quite a generalised way, with little reference to the complexity of the nighttime lightscapes that are being created and the challenges that these pose for the movements of many organisms. This project is therefore clearly of value to two groups of non-academic stakeholders, the general public, and those more directly concerned with the provision of artificial nighttime lighting and with its environmental impacts (government, environmental and conservation agencies, environmental consultancies, & lighting contractors).
(i) General public - the project provides an opportunity to improve public understanding of the form and dynamics, and the ecological impacts, of artificial nighttime lighting, and to encourage a scientifically literate citizenry that understands the profound and rapid effects that arise from anthropogenic environmental changes. The research project will provide a tangible link between the environmental change created by artificial nighttime lighting and the responses of organisms, and we will take advantage of these data to use visual imagery to convey what artificial nighttime lighting is, and the environmental pressure this constitutes and its consequences. In our experience presenting our previous research on the ecological effects of artificial light, we have found that the subject is easily relatable and captures the imagination of a wide audience and has been an effective way to engage the public through participation in events such as Dark Sky Festivals, public talks and through local, national and international media coverage of our research.
(ii) Government, environmental and conservation agencies, environmental consultancies, & lighting contractors - a number of governmental and non-governmental groups have a significant interest in improved understanding of the likely environmental consequences of artificial nighttime lighting, for purposes ranging from shaping their own public engagement programs to making better public lighting policy and on-the-ground management decisions. One of the challenges faced lies in the undoubted complexity of the issues and the associated uncertainties. In particular, while there is a growing consensus among scientists and understanding among policymakers that artificial light has profound ecological effects on many species, the significance of artificial nighttime lighting is not well understood outside of a few local case studies on single species, and as a consequence opportunities for mitigating negative impacts through changes in lighting policies may be missed. We will use the work of the research project to improve understanding of the environmental impacts of artificial nighttime lighting, to explore together what this means for environmental policy and planning, and how best practice can most effectively be promulgated. Mitigating the negative impacts of artificial light on ecosystems often presents a potential win-win situation for policymakers, where environmental, financial, health and social costs could be minimised through low-cost solutions; however identifying and implementing such solutions is often hampered by major knowledge gaps in understanding of the full effects of artificial light in spatially and temporally complex ecological systems. This project will directly seek to address these gaps in existing knowledge.

Publications

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