PD Dr. Hans Jürgen Hahn is a limnologist and ecologist and works as a private lecturer at the Institute of Environmental Sciences on the Landau campus. He is also Managing Director of the Institute for Groundwater Ecology IGÖ GmbH. He is primarily concerned with the ecology of groundwater, springs and stream sediments, but also with the biology of drinking water. Against this background, he is also concerned with climate change and its effects on the landscape water balance.