Abstract: Artificial light at night (ALAN) is a recently acknowledged form of anthropogenic pollution of growing concern to the biology and ecology of exposed organisms. Though ALAN can have detrimental effects on physiology and behaviour, we have little understanding of how marine organisms in coastal areas may be impacted. Here, we investigated the effects of ALAN exposure on coral reef fish larvae during the critical recruitment stage, encompassing settlement, metamorphosis, and post-settlement survival. We found that larvae avoided illuminated settlement habitats, however those living under ALAN conditions for 10days post-settlement experienced changes in swimming behaviour and higher susceptibility to nocturnal predation. Although ALAN-exposed fish grew faster and heavier than control fish, they also experienced significantly higher mortality rates by the end of the experimental period. This is the first study on the ecological impacts of ALAN during the early life history of marine fish.
Keywords: Animals; Ecosystem; Environmental Pollution/adverse effects; Fishes/growth & development/*physiology; Larva/growth & development/physiology/*radiation effects; Light/*adverse effects; Metamorphosis, Biological/radiation effects; Predatory Behavior/radiation effects; Coral reefs; Fish larvae; Light pollution; Metamorphosis; Recruitment
Abstract: Coral reefs represent the most diverse marine ecosystem on the planet, yet they are undergoing an unprecedented decline due to a combination of increasing global and local stressors. Despite the wealth of research investigating these stressors, Artificial Light Pollution at Night (ALAN) or “ecological light pollution” represents an emerging threat that has received little attention in the context of coral reefs, despite the potential of disrupting the chronobiology, physiology, behavior, and other biological processes of coral reef organisms. Scleractinian corals, the framework builders of coral reefs, depend on lunar illumination cues to synchronize their biological rhythms such as behavior, reproduction and physiology. While, light pollution (POL) may mask and lead de-synchronization of these biological rhythms process. To reveal if ALAN impacts coral physiology, we have studied two coral species, Acropora eurystoma and Pocillopora damicornis, from the Gulf of Eilat/Aqaba, Red Sea, which is undergoing urban development that has led to severe POL at night. Our two experimental design data revealed that corals exposed to ALAN face an oxidative stress condition, show lower photosynthesis performances measured by electron transport rate (ETR), as well as changes in chlorophyll and algae density parameters. Testing different lights such as Blue LED and White LED spectrum showed more extreme impact in comparison to Yellow LEDs on coral physiology. The finding of this work sheds light on the emerging threat of POL and the impacts on the biology and ecology of Scleractinian corals, and will help to formulate specific management implementations to mitigate its potentially harmful impacts.
Keywords: Animals; *Anthozoa; Coral Reefs; Ecosystem; Indian Ocean; Oxidative Stress; Photosynthesis; Alan; Ros; corals; light pollution; photosynthesis; physiology
Abstract: The ecological impact of artificial light at night (ALAN) on phenological events such as reproductive timing is increasingly recognized. In birds, previous experiments under controlled conditions showed that ALAN strongly advances gonadal growth, but effects on egg-laying date are less clear. In particular, effects of ALAN on timing of egg-laying are found to be year-dependent, suggesting an interaction with climatic conditions such as spring temperature, which is known have strong effects on the phenology of avian breeding. Thus, we hypothesized that ALAN and temperature interact to regulate timing of reproduction in wild birds. Field studies have suggested that sources of ALAN rich in short wavelengths can lead to stronger advances in egg-laying date. We therefore tested this hypothesis in the great tit (Parus major), using a replicated experimental setup where eight previously unlit forest transects were illuminated with either white, green, or red LED light, or left dark as controls. We measured timing of egg-laying for 619 breeding events spread over six consecutive years and obtained temperature data for all sites and years. We detected overall significantly earlier egg-laying dates in the white and green light versus the dark treatment, and similar trends for red light. However, there was a strong inter-annual variability in mean egg-laying dates in all treatments, which was explained by spring temperature. We did not detect any fitness consequence of the changed timing of egg-laying due to ALAN, which suggests that advancing reproduction in response to ALAN might be adaptive.
Keywords: Animals; Parus major; Alan; light pollution; phenology; timing of reproduction; urbanization
Abstract: Night protection has been a major concern for astronomers since the electrification of cities and is beginning to be recognized as a major environmental problem. In recent years, regulations have been put in place through the establishment of Dark Sky Reserves that impose stringent constraints on lighting practices for cities in protected areas. Astronomers from the Asiago Observatory, located in the Veneto region of Italy, would like to create an area of this nature around their facilities to improve and protect the quality of their astronomical observations. This study assesses the current state of the sky in the region through numerical modelling using the latest improvements to the ILLUMINA model and aims to identify the main contributing sources of artificial light. The explicit calculation of the contribution of private residential lighting helps to discern the origin of the light. We also present a new approach for extracting an estimate of the distribution of lamp technology in a region from images taken from the International Space Station.
Keywords: Skyglow; light pollution; numerical methods; Site testing; Italy; Observatories
Abstract: The degradation of darkness through the use of artificial light at night (ALAN) in and around human infrastructures is termed light pollution. This pollution is intrinsically related to urbanization and spills out from urban areas to affect rural areas and protected areas. The fight against light pollution is being organized in several countries where local communities are experimenting with environmental policies to protect darkness. The challenge bears on both the preservation of biodiversity and the energy transition. In France, a few pioneering rural areas are experimenting with mechanisms that include this dual implication. Two of them provide the case study for this article. We show how these areas turn darkness into a specific resource. We identify three specification processes. The first, obeying an anthropocentric utilitarian rationale, is part of the “economicization” of the environment in the line of shallow ecology. The second, following a rationale of ecocentric conservation, is part of the radical greening of the economy, in line with deep ecology. The third follows an integrated social-ecological system rationale enshrining the interdependence between development and planning and the preservation of biodiversity and energy savings. Specification controversies beset local areas. These areas become incubation rooms, that is, spaces for resolving these controversies that are reflected in a transition operator enabling the local area to take a fresh trajectory in terms of development and planning.
Keywords: Society; Light pollution; France; Europe