got stopped as well. Because of these measures the salt marshes stock increased up to 13.5% at the coasts of North Frisia and Dithmarschen in the years from 1988 to 2014. With a total area of 12.450 ha (2006), 47% of the salt marshes were not grazed at all, 11% were grazed extensively and 38% were grazed intensively. Transport and infrastructure There are some small and medium-sized harbours (Meldorf, Büsum, Husum, Nordstrand, Pellworm, Dagebüll, Wyk auf Föhr, Amrum, Hörnum and List auf Sylt) located at the coast of Schleswig Holstein. The only possibility to reach them is driving through the national park. Responsible for most of the marine traffic are ferries driving to the North Frisian Islands. The ferry traffic routes go through shipping channels in the national park area. A special decree on moving through the Wadden Sea by the Federal Government of Germany applies to the maritime area of the national park shipping channels. The decree allows for example temporal closure of conservation zones for the protection of breeding birds and grey seals or bans on driving during low tide. The seaward part of the national park is signed as a PSSA (Particularly Sensitive Sea Area). The marking also provides extra limitations for marine traffic especially for ships with dangerous loads. These ships are forced to take other routes (more seawards) outside of the PSSA. Very important shipping routes, like the Elbe estuary route to Hamburg are an exception. The area of the Schleswig-Holstein Wadden Sea National Park is located north of a strongly frequented waterway in the southern North Sea. Changing weather conditions, strong storms and limited range of sight are pretty common for the region, so naval accidents are ongoing hazards for the flora and fauna of the national park. But more common than naval accidents are oil-polluted birds due to captains illegally dumping oil into the sea close to the national park. The biggest threat the national park ever experienced happened on 29 October 1998 when the cargo ship MV Pallas, on fire and abandoned, ran aground near the island Amrum. Approximately 244 tons of oil flew into the North Sea. Because of being completely surrounded by the national park area, the supply chain of the islands and Hallig islands goes through the national park inevitably. Besides the supply transported by ships, other essentials like energy, data or water pipes lead through the national park