How are the Mediterranean islands polluted by artificial light at night

Abstract The Mediterranean is considered as a World Biodiversity Hotspot because of the significant reservoir of endemics, which are threatened with destruction. Island ecosystems have special importance for biodiversity conservation in this region. However, most of them are under strong anthropogenic influences: recreational pressures, infrastructure development, fires etc. At the same time, new types of anthropogenic pressures have developed, one of which is the preponderance of artificial light at night (ALAN) and sky glow. This factor has not been perceived as dangerous for people and biodiversity until recently. However, the latest researches show the opposite conclusion: ALAN has a significant influence on reproduction, navigation, behavior, foraging, habitat selection, communication, and social interactions of all living organisms. Therefore, we have estimated the level of light pollution on the fifteen biggest islands of the Mediterranean using tools available from Google Earth Pro, and the New World Atlas of Artificial Sky Brightness in the form of a kmz layer created by Falchi et al. (2016). In addition, islands or their parts without ecological light pollution have been selected. The obtained results argue that light pollution is extremely high on these larger islands; there are no areas with zero-level of ecological light pollution. As well it has been found that the level of light pollution of these islands correlates with their human population density. Nevertheless, there are 49 small islands or their parts with “pristine” skies, and their total area is 118.67 km2. Also, four dark sky refugia (Western (313,593 km2), Adriatic (331 km2), Aegean (12,448 km2), and Eastern (841,195 km2)) were highlighted within the territory of the Mediterranean Sea. That is 46,61% of its total area. Special attention has been paid to protected areas of the region in the context of combating light pollution, as well as the potential for astro-tourism development. Recommendations for changing of the current ALAN-related situation are given.