Small but with big impact! Freshwater pearl mussels need protection in the uppermost corner of European Green Belt

Populations of the endangered freshwater pearl mussel are studied and new conservation methods developed far north of the EGB, in Fennoscandia. This summer, field mappings of Finnish rivers revealed at least ten unknown populations, laying the basis for further research on the species.

An ideal freshwater pearl mussel consisting of different age groups © Heikki Erkinaro

The findings were accompanied by captive breeding activities of freshwater pearl mussel larvae originating from some of the most endangered and currently nonreproductive populations. The reproduction success of the species is being promoted with the aid of the mussels’ intermediate host Atlantic salmon.

Despite that freshwater pearl mussels indicate an ecologically good environmental status when present in a river, the species is endangered worldwide. Failures in reproduction due to extensive water construction are one of the biggest threats. Dams impede free movement of pearl mussel’s obligatory intermediate hosts, salmonid fish. Also, siltation of river bottoms caused by adverse land-use practices result in habitat degradation which is critical especially for the young mussel individuals.

Cross-border cooperation is essential to protect joint freshwater pearl mussel populations in the Fennoscandian part of the Green Belt, because rivers inhabited by this species mostly flow across national borders in a west-east direction.

In the EU-funded project SALMUS, partners from four countries (Finland, Norway, Russia and Sweden) try to map new populations, assess the status of known populations and develop new methods to help conservation work of freshwater pearl mussels. Also, public awareness is being raised about the importance of this species and healthy river ecosystems. For example, nature-tourism operators and school classes are invited to visit mussel rivers.

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