In the 19th century Pearl Mussels were widespread in clean streams of Central Europe. Only one of ten-thousand pearl mussels produces a pearl. But runoff from intensive agriculture led to a decrease of oxygen in the rivers. In the mountaineous region between Czech Republic and Bavaria one of the rare populations has survived. The Bavarian NGO BUND Naturschutz and a Czech school class from As are renaturating the stream "Reuthersbaechlein" to preserve this valuable population.
Images: 1 school project, BN - archive, 2,3 Pearl Mussels, Josef Limberger,