PROJECT DESCRIPTION
BACKGROUND
The ecosystems and native species of alpine rivers and lakes are threatened by the arrival of invasive alien species and point sources of organic pollutants. The presence of the invasive alien North American brook trout (Salvelinus fontinalis) in the lakes of Gran Paradiso National Park has a negative impact on native invertebrate and vertebrate (i.e., common frog Rana temporaria) fauna. It is leading to ecosystem degeneration and local extinction of protected, vulnerable species. Another conservation challenge is hybridisation of the marble trout (Salmo marmoratus, native of the southern Alps) with the brown trout (Salmo trutta trutta) in the Campiglia and Forzo rivers. Finally, some point source of organic pollutants from touristic infrastructures and livestock grazing threaten the water quality and the ecological integrity of some mountain rivers and lakes.
OBJECTIVES
The project set out to improve the biodiversity of high-altitude aquatic ecosystems in the rivers, streams and lakes of the Gran Paradiso National Park, a Natura 2000 site. This would involve: i) eradicating invasive brook trout from 4 high-altitude alpine lakes; ii) removing brown trout (Salmo trutta trutta) from three streams; iii) stocking the three streamswith marble trout; and iv) construct two phyto-pedo-depuration plants to reduce the input of organic pollutants in aquatic habitats, i.e., alpine lakes and rivers. Achieving the objectives of the project would contribute to the EU's Biodiversity Strategy to 2020 and Biodiversity Action Plan in relation to removal of invasive alien species and improving water quality.
RESULTS
The BIOAQUAE project had a positive impact on the biodiversity of high-altitude aquatic ecosystems. Its best practices have been applied in similar sites. It succeeded in completely eradicating invasive brook trout from the four alpine lakes in Gran Paradiso National Park, removing more than 20 000 fish in total. The combined use of gill-nets and electrofishing had never been attempted before in the Alps. If accompanied by proper conservation measures (a fish-stocking ban), the used methods proved to effective in reversing the negative effects of introduced fish in lakes of different size and habitat complexity. The same non-invasive (i.e., without negative impacts on native semi-aquatic vertebrates and aquatic invertebrates) technique has been replicated in Croatia and Spain. The positive benefits from removing brook trout on the biodiversity of the high-altitude aquatic ecosystems and in particular, on nektonic and benthonic macro-invertebrates, large zooplankton species and the common frog was already evident at the end of the project. Contrary to expectations, the project team found no marble trout present in the Campiglia and Forzo rivers. However, a small population of genetically pure marble trout was found in the Roc stream. The beneficiary established a hatchery for marble trout in the Piantonetto valley, which was also intended to become an education centre during and after the project. Marble trout from the Roc population and from rivers outside the national park bred at the hatchery and fry were subsequently released at four locations. Monitoring in spring 2017 showed that 10% of the released fry and juvenile trout were healthy and developing normally. This indicates that the selected streams of Gran Paradiso National Park are able to host marble trout and thus can be used as conservation area for the species. The hatchery will continue to breed marble trout following the LIFE project. Two bio-filtration systems using plants and zeolite were installed at high altitude for treatment of wastewater from a mountain hut and stable. Preliminary data indicated that the plants have reduced nutrient levels of the treated water, which should have a positive impact on the quality of the downstream aquatic ecosystems. It is also expected to lead to a significant reduction in water purification costs for the hut and stable. Such treatment systems could be cost-effectively installed in other alpine locations for similar socio-economic and environmental benefits. Further information on the project can be found in the project's layman report and After-LIFE Conservation Plan (see "Read more" section).
