A thick-shelled river mussel, Unio crassus

Between 2012 and 2016, researchers at Karlstad University have worked together with several county boards in southern Sweden in the EU-funded life project “Unio crassus for life” (målarmusslans återkomst). The thick-shelled river mussel (Unio crassus) is one of the most threatened bivalve species in Europe. In Sweden, the distribution of the species has decreased with 50% over the last 100 years.

In twelve streams in southern Sweden, a total of 300 km has been restored as part of the project to improve the habitat for the mussel. The project has also examined what fish species that are suitable hosts for the obligate parasitic larvae of the thick-shelled river mussel. Species like minnow (Phoxinus phoxinus), bleak (Alburnus alburnus) and bullhead (Cottus gobio) seem to be important hosts for the mussel. In addition, juvenile mussels have been reared in captivity with the aim to successfully reintroduce them into the wild.

The project has been very successful, and has now been nominated as one of the best EU life projects. The ceremony where the best project will be awarded is held in Brussels 23 May. Martin Österling, associate professor at Karlstad University, will attend the ceremony. We wish Martin and all other people that have worked on the Unio crassus for life project the best of luck, and we keep our fingers crossed that Unio crassus for life will be awarded the best EU life project.

Read more about the project at the Unio crassus for life official web page, or on the Skåne and Södermanland county board web pages.

The project has also gotten publicity in media, and you can read more about the project on svt or Smålands-tidningen.

Watch a short film about the project here.

On Friday, 15 December, from 13:00, Stina Gustafsson will defend her PhD-thesis “Habitat compensation in nature-like fishways – effects on benthos and fish”. Paul Giller (Cork University, Ireland) will be the opponent, and Frauke Ecke (SLU, Sweden), Brendan McKie (SLU, Sweden) and Jouni Taskinen (University of Juväskylä, Finland) constitute the grading committee. The defense will take place in 1B306 (Fryxellsalen) at Karlstad University. Everyone is welcome to attend!

In the abstract to the thesis, Stina Gustafsson writes: “The construction of nature-like fishways has become an increasingly common measure to restore longitudinal connectivity in streams and rivers affected by hydroelectric development. These fishways also have the potential to function as habitat compensation measures when running waters have been degraded or lost. The habitat potential has however often been overlooked, and therefore the aim of this thesis was to examine the potential of nature-like fishways for habitat compensation, with special focus on the effect of added habitat heterogeneity. 

This thesis examines the effects of habitat diversity on the macroinvertebrate family composition and functional organization in a nature-like, biocanal-type fishway. The biocanal contained four habitat types; riffle, pool, braided channel and floodplain. The effects of habitat diversity and large woody debris on brown trout habitat choice was also investigated in the biocanal. In addition, and prior to introduction of the threatened freshwater pearl mussel into the biocanal, the suitability of different brown trout strains as hosts for the mussel was examined. 

The results show that the habitat heterogeneity in the biocanal contributed to an increased macroinvertebrate family diversity. The functional organization of the macroinvertebrate community suggests that it was a heterotrophic system and more functionally similar to the main river than to the small streams that it was created to resemble. Brown trout habitat choice studies showed that high densities of large woody debris increase the probability of fish remaining at the site of release. Testing of different brown trout strains as host for the freshwater pearl mussel revealed that both wild and hatchery-reared brown trout strains were suitable hosts. In summary, the results indicate that it is possible to create a fish passage with added value through its high habitat function and that nature-like fishways can be designed to reach multiple species restoration goals.”

The thesis is available online here.

On Thursday, 14 December 14:00, Brendan McKie, one of the members of the grading committee, will give a presentation titled:  “River restoration and biodiversity and ecosystem functioning in tributaries of the Vindel River: The importance of restoration intensity and time”. The seminar will be given in room 5F416, at Karlstad University. Everyone is welcome to attend also the seminar.

The Fyleån creek (photo from uc4lifeconference.se).

The international river restoration conference “Restoring floodplains, habitats and connectivity using mussels and brains” will be held in Lund, Sweden, on 28–30 September, 2016. The organizers write: “Conference objectives are to highlight experiences and results gained from a wide range of river restoration projects focusing on rehabilitation of species of freshwater mussels and fish. Mussels and fish are often used as indicators and flagship species while restoring rivers. But are they any good? If so – why? The first two days will focus on presentations by invited experts and conference participants who want to present their work. The third day includes field visits to Fyleån Creek, Klingavälsån River, both sites re-meandered, and the Hemmestorp Mölla rearing facility. We look forward to seeing you in Lund!”

Registration and more information on www.uc4lifeconference.se.