Survival of juveniles in Klingavälsån River and Fyleån Creek

Written by Ivan on . Posted in BOB'S BLOG, Communication, Re-introduction of Unio crassus, River Fyleån, River Klingavälsån


One year has gone by since the restauration of Klingavälsån, and two years for Fyleån, and we are now trying to find out how our cultured juvenile mussels (Unio crassus) respond to their new environment. This year a new method, Whitlock-Ö-boxes (2016) has been developed to test this. The Whitlock-Ö-box (2016) is a box constructed with holes in the walls so that water can flow thru it. Inside the box tubes with mussels have been placed and fixed. The tubes contain holes in the wall covered with a 200 um net, so that water can run through and the mussels stay inside. The box itself is attached to an iron stick at the bottom of the river. Every week the boxes are collected and brought back to the lab at the Hemmestorps Mill where survival rates are examined. The results so far are encouraging and the juveniles seem to like their new environment.

/ Tina, Valentina och Martin

New juvenile mussels for Fyleån and Klingavälsån 31/08/2015

Written by lea on . Posted in Karlstad University, River Fyleån, River Klingavälsån


The field season 2015 comes to an end. Last Thursday, Tina, Valentina and me placed out juvenile mussels that have been cultured at the Hemmerstorps mölla lab facility to Klingavälsån and Fyleån. Both streams were habitat restored in 2013 and 2014. Back in time the river was channelized, whereby aquatic habitats were destroyed. Among other reasons, this is why Unio crassus has been extinct in those rivers. The restoration measures brought back the original meanders of the rivers. Post-restoration re-introduction measures of Unio crassus have been taken place as part of our conservation project UC4LIFE. For the current mussel re-introduction we used hole-plates, also called Buddensiek cages. In each hole-plate, juvenile mussels, encaged with gauze nets preventing the small mussels of 300-400 µm to escape, were placed. The cages were then fixed on iron sticks installed on the river bottom. Now, it’s up to the small mussels to survive. Earlier re-introduction trials using Buddensiek cages in Germany or Luxembourg, for example, were successfully rearing mussels with this method. In one year we know more how the Swedish mussels perform it the hole-plates.

/Valentina, Tina and Lea

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