Introduced to the 1960s, the North American brook trout has caused damage to the ecosystems of four lakes in the Gran Paradiso National Park in Italy: its rapid spread has destroyed many species of zooplankton, which normally provides food for other animal species. It has thus displaced native grass frogs and beetles. This is the result of studies carried out over several years by LIFE+Bioacquae, a project run by the Gran Paradiso National Park. In spring 2013 steps were taken to begin removing the brook trout as a protective measure. At the same time initiatives are planned for the preservation of the local marbled trout.
There are similar problems in the Double Lake - Dvojno jezero - in the Triglav National Park. In 1991 the arctic char was introduced, which spread just as rapidly and destroyed zooplankton. The consequence was today's increase in nutrients in the waters. Various new algae species now grow in the lake. One particular problem in that there is an underground link between the polluted lake and drinking water sources.
CIPRA Slovenia has now initiated its project "Let's clean up the Double Lake!" with the aim of restoring the equilibrium of the lake ecosystem and improving water quality.
Sources and further information: www.pngp.it/bioaquae (it), www.cipra.org/slovenija (sl)