dr.ir. LAJ (Leo) Nagelkerke

dr.ir. LAJ (Leo) Nagelkerke

Assistant professor in fish biology and fisheries

Leo Nagelkerke (1966) has been working as a university lecturer and researcher at the Aquaculture & Fisheries Group at Wageningen University since 1999. In 1997 he received his doctorate (cum laude) for his work on the fish community of Lake Tana in northern Ethiopia, which was carried out at the Experimental Zoology Group of Wageningen University. The study encompassed many aspects, such as feeding ecology, spawning behaviour, and even taxonomy: eight new Labeobarbus species were described. However, the central theme of the research was the relationship between body structures and food intake. This ecomorphological approach is more than correlative, but explicitly seeks causal, and quantitative relationships between the fish’s traits and its functioning.

After his PhD graduation Leo worked some time as as an ecological advisor, where he collaborated on the Handbook on fish stock sampling for STOWA and led a number of projects on water quality and fish stock management. In 1999 he returned to Wageningen University, this time at the Aquaculture and Fisheries Group, where he is involved in diverse projects, mostly focusing on changes in fish communities due to fishing and other environmental pressures (e.g. in the Eritrean section of the Red Sea and Lake Victoria in Tanzania), and with the relation between fish migration, recruitment of young fish and hydrological changes (Volga River, southern Russia, but also the Wadden Sea and the Rhine River in the Netherlands).

Besides in research Leo is very interested in teaching and involved in many of the chair group’s courses. In his spare time he is an apt birdwatcher and cooperated in many bird counts for Sovon Vogelonderzoek Nederland. In addition, he regularly writes pieces on fish, birds, and nature in general, for a wider audience.

Functional traits and fish communities in a changing world

The relationships between the morphology and functioning of organisms have never stopped to intrigue me. In my current research I am trying to understand changes in fish communities from the perspective of the functionality of individual organisms rather than from a taxonomic view. As some of the major challenges of a fish are how to find enough food, without being eaten yourself, my focus is on the feeding apparatus on fish: which functional traits can be derived from the fish’s morphology, what are the causal links with functionality, and can this actually help explaining the phenomena we see? Or even: can a thorough understanding of functional traits be used for predicting future developments in fish communities? Recent work has shown that functional traits can potentially be used to assess the impact of invading alien species on native fishes.