Coastal glow : gauging light in Maltese coastal areas whilst exploring the impact on turtle nesting preferences

Abstract

Artificial Light at Night (ALAN) is an increasingly significant anthropogenic pressure affecting coastal and marine ecosystems worldwide. Species that rely on natural darkness for key biological processes, such as the Loggerhead turtle (Caretta caretta), are particularly vulnerable. Despite Malta being among the most light-polluted countries globally, and albeit recent increases in turtle nesting activity on its beaches, the influence of ALAN on local nesting-site selection has not yet been systematically studied. This dissertation examines the extent of ALAN along key Maltese nesting beaches and evaluates how light intensity interacts with physical beach characteristics to influence nesting suitability. Using data collected by Nature Trust Malta (NTM), combined with satellite-derived radiance measurements from the VIIRS Day-Night Band, this study assesses five primary nesting beaches: Gnejna, Golden Bay, Għajn Tuffieħa (Riviera), Għadira, and Ramla. Environmental variables examined include beach elevation profiles, sand-grain texture, vegetation proximity, lunar phase, cloud cover, and long-term changes in beach depth. Radiance data from 2012–2025 were analysed to determine spatial and temporal trends in coastal illumination. Results show clear variation in beach quality and ALAN levels. Beaches with lower radiance, gradual slopes, and suitable substrate—particularly Ramla—correspond with successful nesting attempts. Conversely, beaches exposed to high artificial illumination, especially parts of Għadira, show reduced suitability and fewer nesting events. Long-term radiance trends indicate increasing light pollution across several sites, consistent with other findings in other countries. These findings are not entirely conclusive, as they require further studies in order to establish whether nesting site selection is effected by the physical beach properties, ALAN, or whether it is the combination of the physical characteristics which directly alter ALAN levels which have the greatest impact. The study highlights the urgency of implementing improved lighting management, enforcing coastal protection guidelines, and adopting ALAN-reduction measures in sensitive habitats to help ensure the long-term viability of sea turtle populations in Maltese waters.