Summer is not only a bathing season, motor boats are also increasingly romping on German lakes. However, increasing leisure shipping has a negative impact on the nature and living environment of the lakes. A new study now shows how the ship waves bounced on the shore damage plants and animals and even release the climate -damaging methane from the sea sediment. In order to relieve the lake ecosystem, researchers are calling for stricter rules for the boat trip in Germany.
The European Water Framework Directive stipulates that all European waters should be in a good ecological condition by 2027, for example, offer clean water and intact habitats. However, many lakes in Germany are still a long way off. The reason for this includes fertilizer entries from agriculture, pollution from pollutants and garbage, but also motorized water sports.
Danger zones in danger
Researchers around Frank Peeters from the University of Konstanz have now systematically examined the influence of motor boats, excursion ships, jet skis and Co. on German lakes. To this end, the team carried out intensive measurements on several lake landscapes in Germany – including on Lake Constance, at Lake Starnberg in Bavaria and at the Röblinsee in Brandenburg. Peeters and his colleagues determined the influence of ship waves that hit the shore and recorded how much boats and ports install bank areas. The team also examined the possible release of pollutants.
The result: “The traffic of large passenger ships and motor boats is burdening the lake shore,” reports Peeters. “The ship waves affect animals and plants in the shallow water zone and can lead to the swirling and frightening of the sediments.” In turn, methane -containing gas bubbles can detach from the sediment and get into the atmosphere as greenhouse gases. These effects are particularly strong with high waves and with frequent waves, as the team found out. The reed belt and other aquatic plants near the shore can be damaged by the waves. The same applies to nests of birds or children’s rooms of water animals that are hidden in these plant communities.
Investigation points also cause damage
Even if the sports boats and passenger ships are only quiet in the harbor, they continue to create environmental problems. Among other things, pollutants get into the water from the coatings of the ship flours. Also problematic: the numerous boats and ports install ecologically valuable habitats in the bank zone, as Peaeters and his colleagues report. With 112 watercraft per square kilometer sea surface, Lake Constance is an extreme example. This enormous fleet corresponds to one boat per five meters of bank. There are also buoy fields, bars and ports that take an area of more than 4.4 square kilometers, as the researchers have determined.
Peeters and his team are therefore calling for binding rules to reduce the strain on the lakes by motorized water sports. This includes, among other things, a central digital boat register that records all motorized boats, as well as a boat tax that is based on size, engine output and pollutant emissions and should benefit environmental protection. Stricter guidelines for the behavior of the motor boats and jet skis on the water could also help. Since smaller and slowly moving boats generate less strong waves, Peeters and his colleagues recommend limiting the permissible size of leisure ships and their permitted speed – at least in previously designated protective zones. This is the only way to ensure the protection of the lakes and their sensitive ecosystems in the long term.
Source: University of Konstanz; Specialist articles: Constance online publication system, DOI: 10.48787/Kops/Subolakes/352-2-7aspyt48WVDP7
