South of the city of Marburg, in the districts of Gisselberg, Ronhausen and Cappel,  around 100,000 m³ of soil was moved over a length of 1.5 km in order to connect the Lahn with its banks and create diverse habitats.

Branching and widenig of the river tube, the creation of gravel deposits and the installation of dead wood now ensure a diversity of flow and structures in the watercourse itself and the adjacent floodplain. The watercourse develops as its own dynamics.

This benefits fish, which require very different water structures during the course of their lives: In addition to good water quality, the river must also provide  food, spawning sites and protection from predators. Especially, animal species whose habitats are threatened by changes in climatic conditions may settle in the riparian areas. These include endangered amphibians such as the natterjack toad (Epidalea calamita), wading bird species such as the snipe (Gallinago gallinago), lapwing (Vanellus vanellus) or little ringed plover (Charadrius dubius), and various bat species such as the lesser bearded bat (Myotis mystacinus) or the greater evening bat (Nyctalus noctula). Targeted measures, such as the design of riparian and floodplain areas or the creation of shallow water zones and small waterbodies, will help to preserve these "climate losers".

The chances for this are good, for the renaturalized section of the river links the nearby protected areas "Auenverbund Lahn-Ohm" (LSG), the bird conservation area "Lahntal zwischen Marburg und Gießen" and the nature reserve "Unterm Wolfsberg", where the rare species can be found. The "Gisselberger Spannweite" is therefore of outstanding importance as a "stepping stone" for networking the valuable habitats.

The funds from the LIFE project "Living Lahn" were increased to a total of 1.8 million euros with funds from the Hessian fishery and the Integrated Climate Protection Plan 2025 (IKSP) in order to achieve the greatest possible effect for nature. The areas were provided by the city of Marburg.