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

Fishing for Södermanland-fish infested with mussel larvae 03/07/2015

Written by lea on . Posted in Karlstad University, River Svärtaån, Södermanland County, Studies


At the end of June we conducted a 4-day fishing event in the two streams Kilaån and Svärtaån in Södermanland. Fish that are infested with mussel larvae were our targets. Martin Škerlep, Helena Herngren and I electro-fished over stream stretches with present mussel populations where we also set out fish traps overnight. The idea was to transport the fish captured to the UC4LIFE-lab facility in Skåne, where we can collect juvenile mussels that fall off their fish hosts after successful transformation from a mussel larvae to a juvenile. In this way, the host fish species used by Unio crassus can be identified properly. However, as different mussel species exist in the two streams Kilaån and Svärtaån, DNA analysis of the juvenile mussels collected need to be conducted to guarantee the host fish suitability for the right mussel species.

After successful fishing, a long fish transport by car, the transfer of the fish to aquaria tanks fit with nets were juvenile mussels can be collected, we discovered the first juveniles after only one day! Over the past week more juveniles have been dropping off the fish. To mention a few host fish candidates: Common bleak (Alburnus alburnus), Bullhead (Cottus gobio), Perch (Perca fluviatilis), and Ruffe (Gymnocephalus cernuus). The results of a DNA analysis of the juveniles will soon tell us which fish species Unio crassus uses as host in Södermanland. We are all curious!

Greetings from Skåne!


Mussel translocation

Written by lea on . Posted in Karlstad University, Project sites, Studies


Last week, a translocation measure of adult mussels from the streams Bråån and Tommarpsån to the habitat restored rivers Klingavälsån and Fyleån has been started. Our aim is to get more information about the performance of adult mussels in the new rivers. Therefore, we collected mussels from two high-density mussel populations and tagged each individual mussel before translocation. We will follow the mussels over the whole season and investigate how much they move, which micro-habitat they prefer and how they aggregate within each other.



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