Archive for oktober, 2012

HÖST I VACKRA BRÄKNEÅN

Written by Ivan on . Posted in Bräkneån

I Bräkneån är havsöringen är på väg upp från Östersjön och leken är med andra ord på G. Undertecknad fick genom Andreas och Jonas försorg en ordentlig genomgång av hur LIFE-åtgärderna skall genomföras i Bräkneån. Fokus ligger på att förbättra vandringsmöjligheter för målarmusslans värdfiskar och andra vattenlevande organismer. Intresserade markägare slöt upp och planerade åtgärder diskuterades. Samsyn är UC4LIFE-projektets ledord, och jag  är övertygad om att slutresultatet kommer bli fruktsamt, för såväl ån och dess invånare, inklusive markägare och lokala intressen. Bräkne-Hoby folkhögskola och fiskintresserade studenter välkomnas givetvis ombord detta spännande projekt?

UC4LIFE//Ivan

Fish examination and preparation for further DNA analysis 24/10/2012

Written by lea on . Posted in Musslans värdfisk

After the summer many fish, caught and preserved in ethanol, are on hand to be examined for glochidia infestation at Karlstads University. These days the focus lies on the natural infestation of fish caught in stream stretches with mussel populations. Therefore, fish, mainly Phoxinus phoxinus (minnow/elritsa) and Cottus gobio (bullhead/stensimpa) from the River Bråån and Tommarpsån are dissected and gills cut off. By means of stereomicroscopes the +/- 200 µm large mussel larvae (glochidia) can be counted. Unfortunately, the colors of fish gills and glochidia are very similar, thus counting has to be done very thoroughly. As suitable host-fishes encapsulate glochidia trough fish-gill tissue which overgrows the larvae, small humps are visible on the fish gills.

Besides counting of glochidia, transferring them in small Eppendorf tubes has to be done. Those samples are then taken to Stockholm where I’ll run DNA analysis at the Swedish Museum of Natural History in November. The purpose of those analyses is to figure out the host-fish species for Unio crassus, i.e. as glochidia from different mussel species (e.g. Unio tumidus/pictorum) are hard to morphologically identify it is important to know if fish were also infested by other mussel species than Unio crassus.

/Lea

Bullhead, – and?

Written by Ivan on . Posted in Studier

After some intense days sampling fish we conclude that we have potential host fish species for the thick shelled river mussel/tjockskalig målar mussla (Unio crassus), both upstream and downstream the project site in Fylan. Bullhead/Stensimpa (Cottus gobio), minnow/elritsa (Phoxinus phoxinus) and brown trout/öring (Salmo trutta, picture above) dominated the catches. We also caught European eel/ål (Anguilla anguilla) and crayfish/signalkräfta (Pacifastacus leniusculus) at some sites.

We thank Skönadal and Simon Lundin for the help we got during the field work!

Salute//Ivan and Marie

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