Franz Hölker

Dr. Franz Hölker is a Senior Scientist and Research Group Leader at the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB Berlin) and holds the position of Associate Professor (Privatdozent) in Zoology at the Department of Biology, Chemistry and Pharmacy, Freie Universität Berlin. Since 2022, he has served as Programme Area Speaker for 'Aquatic Biodiversity in the Anthropocene' at IGB Berlin, leading research on ecological responses to anthropogenic pressures.

• Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB Berlin): Senior Scientist, Research Group Leader since 2008
• Freie Universität Berlin: Associate Professor (Privatdozent) for Zoology since 2009
• 2012-2017: Deputy Head of Department Ecohydrology, IGB

Dr. Hölker earned his Diploma in Biology from the University of Hamburg in 1992, completed his doctorate there in 1999 on fish bioenergetics in eutrophic lakes, and achieved his Habilitation at Humboldt-Universität zu Berlin in 2007 with research bridging ecology, behavior, physiology, and modeling in aquatic food webs.

Dr. Hölker's research primarily focuses on freshwater ecology with particular expertise in light pollution, ecophysiology, night ecology, ecological modeling, and citizen science. His work investigates how artificial light at night (ALAN) affects aquatic ecosystems, including impacts on fish physiology, insect behavior, and broader ecological community dynamics. He has pioneered research on the ecological consequences of skyglow and developed methodologies for measuring and assessing ecological light pollution. His research group at IGB Berlin employs a combination of field measurements, laboratory experiments, and modeling approaches to understand how light pollution alters species interactions, community composition, and ecosystem functioning in aquatic environments.

His extensive publication record demonstrates a consistent focus on understanding anthropogenic impacts on freshwater systems. Recent work shows increasing emphasis on interdisciplinary approaches, combining ecological field studies with modeling techniques to address complex environmental challenges. His research spans from organism-level physiological responses to ecosystem-level consequences of light pollution, with growing attention to conservation applications and citizen science engagement. The trend in his publications reveals expanding scope from fish ecology to broader ecosystem impacts, with increasing international collaboration and policy relevance.

Dr. Hölker has led significant research projects examining the impacts of artificial light at night on freshwater ecosystems, often involving international collaborations across Europe. His work has contributed to policy discussions on sustainable lighting practices through participation in projects like the 'White Paper Citizen Science Strategy 2030 for Germany' and collaborations with lighting professionals to develop ecologically sustainable outdoor lighting guidelines.

He leads a research team investigating the ecological impacts of light pollution, with particular focus on how artificial lighting affects nocturnal processes in freshwater ecosystems. His group has developed innovative methodologies for measuring ecological light pollution and has conducted extensive field and laboratory studies to document the impacts of different light spectra and intensities on aquatic organisms. The team's work has significant implications for conservation biology, particularly regarding the protection of nocturnal biodiversity in increasingly illuminated landscapes.