Causes and consequences of artificial light at night for biodiversity and ecosystem functioning

Eva Knop
Agroscope, UniBE/UniZH

Artificial light at night is a rapidly increasing perturbation at night, and considered as a major global change driver of the 21st century. It can cause alterations in physiology and behaviour of organisms, thereby increasing mortality, reducing reproduction as well as altering species abundances and community composition. Yet, its consequences for biodiversity, species interactions and ecosystem functioning are largely unknown. I will first focus on nocturnal plant-pollinator communities and show that they are diverse and have long been neglected in temperate regions. I will then show how artificial light at night poses a threat to these communities with negative consequences for plant reproductive success. Furthermore, by merging diurnal and nocturnal pollination sub-networks I will show that the structure of these combined networks tends to facilitate the spread of negative consequences of artificial light at night from nocturnal to daytime pollinator communities. Finally, I will add an antagonistic interaction to the system, namely seed predation, and show that its strongest negative effect on plant fitness is beyond the area directly illuminated by artificial light at night. Together, this suggests that the ecological consequences of artificial light at night might propagate from the nocturnal to the diurnal community, and that they alter ecosystem functioning at a larger spatial scale than previously thought.

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