Lightscapes ALANIS - ALANIS: Impacts of Artificial Light At Night on pelagIc ecosystems in European Seas

Light plays a huge role in ocean life — not just for powering photosynthesis, but also for guiding how animals find food, avoid predators, and move through the water. But human activities are changing these natural light patterns. Coastal darkening, caused by things like pollution and algae blooms, blocks sunlight from reaching underwater, while artificial light at night (ALAN) from cities and ships adds extra light. These changes can disrupt critical behaviors such as daily vertical migration of zooplankton, with cascading effects on marine food webs and ecosystems. The ALANIS project investigates the spread and impact of ALAN in contrast with coastal darkening, using a comprehensive, cross-regional research approach that combines advanced light measurements, controlled experiments, field studies, and ecosystem modeling. By integrating physical and biological data with remote sensing and experimental observations, ALANIS aims to create a risk and sensitivity map for European waters, informing stakeholders about potential impacts on key ecosystem functions such as carbon export.

In aquatic environments natural light not only determines the rate of photosynthesis as primordial energy source but also critically influences trophic interactions throughout the entire food web. Light modulates visual predation by many predators as well as predation avoidance strategies by the prey and thus structures the vertical organization of aquatic ecosystems. Alterations of light, a reduction of underwater light intensity due to coastal darkening (CD) or additional light at night from artificial light sources (ALAN) have the potential to strongly effect zooplankton diel migration patterns with consequences to whole marine ecosystems. In ALANIS, we will investigate the proliferation of ALAN from coastal activities and shipping and its impact on organismic behaviour such as vertical migration and on key ecosystem functions, while also considering counteracting effects of CD. We will apply a cross-basin state-of-the-art research pipeline approach, linking spectrally resolved light measurements, single species lab and in situ mesocosm studies, with community-wide field experiments and ecosystem modelling. Experimental and observational study sites will cover different regions. The expected results will provide the necessary fundamental physical characterization of underwater ALAN and will deliver an assessment of zooplankton photo-responsiveness and -behavioural thresholds. Remote sensing data of ocean brightness at night and long-term observations of ocean colour will be used to establish an atlas of ALAN for European waters. This ALAN risk map together with the biological and physical knowledge leveraged at the study sites will be integrated into a mechanistic modelling approach for producing a sensitivity map of potential impacts of ALAN and CD on key ecosystem functions such as export flux. Collaborative communication, dissemination, and outreach of ALANIS results will efficiently inform decisions and actions of a diverse group of stakeholders.