The freshwater pearl mussels can occasionally produce beautiful, shimmering pearls. For a long time in history they were harvested in great numbers to satisfy the vanity of royals around Europe. In more recent times the threats have come from dams, forestry and pollution. But the molluscs have managed to survive, and even thrive in some locations. One of them is Gäddbäcken, a crystal clear stream near Vilhelmina in northern Sweden.
In an effort to help this mussel population thrive even more, biologist Nicklas Wengström has tried to move some specimens from the dense population near the streams mouth, upstreams towards the source. One year has passed since, and he is now back with two colleagues to check for the results.
Published in
Forskning & Framsteg, with text in Swedish by Anna Liljemalm.