Background The project targets two main problems: the impact of invasive alien species on the natural ecosystems and their endemic species; and the impact of organic pollutants discharged into alpine rivers and lakes. In alpine lakes, which originally lacked fish species, the endemic fauna (including zooplankton, arthropods, Rana temporaria, etc.) is threatened by the North American brook trout (Salvelinus fontinalis), leading to ecosystem degeneration and local extinction of protected, vulnerable species. In some rivers (e.g. Campiglia and Forzo), the native trout (Salmo marmoratus) hybridises with Salmo trutta subsp. fario. Tourism and livestock farming also give rise to the contamination of water with organic pollutants, which also contributes to local environmental degradation. Objectives The project’s overall aim is to improve the biodiversity of high altitude aquatic ecosystems in the rivers, streams and lakes of the Gran Paradiso National Park. Specific objectives include: To eradicate exotic fish species (Salvelinus fontanilis) from three small and one large high altitude lake; To improve the conservation of the Habitats Directive Annex II-listed marble trout (Salmo marmoratus), restocking three streams with pure individuals and removing Salmo trutta trutta individuals; To establish plant-based filtration systems in order to reduce organic pollution in two lakes arising from waste water coming from high altitude herding activities and tourism in mountain refuges; This proposal therefore contributes to the objectives of the Communication on “Halting the loss of biodiversity by 2010 and beyond” COM(2006)216 – addressing some of the priorities listed in the Biodiversity Action Plan (invasive alien species eradication and improving water quality). Expected results The complete eradication of alien brook trout from three small high-altitude alpine lakes; The eradication of alien brook trout from one large high-altitude alpine lake; The improvement of the three autochthonous marble trout populations present in the SCI; The improvement of aquatic biodiversity in the habitats in and around the Nivolet lake; The improvement of aquatic biodiversity in the habitats in the Pian delle Muande area.