Pieter Hendrik Nienhuis: Aquatic Ecologist and Environmental Scientist

Prof. Dr. Pieter Hendrik (Piet) Nienhuis worked for almost 40 years in all aspects of aquatic ecology and environmental science and retired on 31 October 2003. He can be characterised as a distinguished scientist, shaped in an applied estuarine and aquatic research ambience of the former Delta Institute for Hydrobiological Research (DIHO) in Yerseke in the Netherlands. His appointment as a full professor at the Radboud University Nijmegen offered him a challenging step from monodisciplinarity in ecology, via multidisciplinarity in the application of ecological knowledge in river science to interdisciplinarity in environmental science and management. This paper describes his education, teaching activities, research, scientific publications, science management, and significance for various scientific disciplines. He made important contributions to biosystematics of angiosperms and algae, the ecology of seagrasses, nutrient cycling and eutrophication in estuarine ecosystems, and the integrated modelling of the ecological functioning of estuaries. Subsequently, he paid much attention to environmental problems in river basins, ecological rehabilitation and sustainable development. His work influenced the view of ecologists, aquatic scientists and water managers in the Netherlands as well as abroad, in particular regarding the drawbacks of compartmentalization of the estuaries and the importance of connectivity and morphodynamics in river systems. In hindsight, it appears as a logical line that he gradually moved from estuarine ecological research that became increasingly driven by societal and environmental problems to the field of environmental science and management.