Stina Gustafsson presenting her thesis.

Last Friday, Stina Gustafsson successfully defended her PhD-thesis Habitat compensation in nature-like fishways – effects on benthos and fish”. Paul Giller (Cork University, Ireland) was the opponent, and Frauke Ecke (SLU, Sweden), Brendan McKie (SLU, Sweden) and Jouni Taskinen (University of Juväskylä, Finland) constituted the grading committee.

Stina Gustafssons supervisors during her PhD were Martin Österling and Olle Calles.

The thesis is available online here. Contact Stina Gustafsson for questions and additional information.

 

A thick shelled river mussel (Unio crassus).

Lea SchneiderAnders Nilsson, and Martin Österling from Karlstad University, and Johan Höjesjö from University of Gothenburg, recently published the scientific article ”Local adaptation studies and conservation: Parasite–host interactions between the endangered freshwater mussel Unio crassus and its host fish in Aquatic Conservation. In the article the authors present a study on thick shelled river mussels (Unio crassus) and their interaction with potential host fishes originating from the same or a different river than the individual mussels. In the abstract they write:

”1. Parasite–host interactions can involve strong reciprocal selection pressure, and may lead to locally adapted specializations. The highly threatened unionoid mussels are temporary parasites on fish, but local adaptation has not yet been investigated for many species.

2. Patterns of local adaptation of one of Europe’s most threatened unionoids, the thick-shelled river mussel (Unio crassus) were investigated. Eurasian minnows (Phoxinus phoxinus) from two rivers (separate drainage areas) were cross-infested in the laboratory with sympatric and allopatric mussel larvae, while bullheads (Cottus gobio), inhabiting only one of the rivers, were infested with sympatric or allopatric mussel larvae. Larval encystment, juvenile mussel excystment and survival were measured.

3. For one river, but not the other, juvenile excystment from P. phoxinus was highest when infested with sympatric mussels. The opposite pattern was found for C. gobio in this river, where juvenile excystment and post-parasitic juvenile survival from allopatric C. gobio were highest. The results thus cannot confirm local adaptation of U. crassus to P. phoxinus in the study rivers, as excystment was not consistently higher in all sympatric mussel–host combinations, whereas there were potential maladaptive signs of U. crassus in relation to C. gobio. There was no loss of encysted larvae 3 days after infestation until juvenile excystment. Most juveniles were excysted between 17 and 29 days after infestation, and the numbers of excysted juveniles increased with fish size.

4. The results have implications for parasite–host ecology and conservation management with regard to unionoid propagation and re-introduction. This includes the need to (1) test suitability and adaptation patterns between U. crassus and multiple host fish species, (2) evaluate the suitability of certain unionoids and host fish strains after more than 3 days, and (3) determine whether large fish produce more juvenile mussels than smaller fish.”

Access the paper here: ”Local adaptation studies and conservation: Parasite–host interactions between the endangered freshwater mussel Unio crassus and its host fish”, or email any of the authors.

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Adult thick shelled river mussel (Unio crassus) from the River Tommarpsån, Sweden.

Lea Schneider, Anders Nilsson, and Martin Österling from Karlstad University, recently published the scientific article ”Evaluating temperature- and host-dependent reproduction in the parasitic freshwater mussel Unio crassus” in the journal Hydrobiologia. In the article they present a study on the thick shelled river mussel (Unio crassus) and its release of glochidia (mussel larvae) in different temperature regimes.

In the abstract they write: ”Adaptation to temperature regimes and host presence may enhance fitness in parasites. In an experimental study, we evaluated the timing of glochidia release by Unio crassus subjected to three spring water temperature regimes in the presence and absence of the host fish Cottus gobio. The timing of glochidia release was delayed at (i) constantly low temperatures (<10°C), in contrast to earlier and pronounced releases at (ii) natural temperature increases that level off at intermediate temperatures (10–15°C), and (iii) higher-than-normal temperatures (10–20°C). Mussels from treatment (i) that had not released glochidia during the experiment did so soon after being moved to the temperature in (ii), indicating a temperature threshold for glochidia release. Neither host fish presence nor the combined effect of temperature and host fish presence significantly affected the timing of glochidia release. The treatment with natural spring water temperatures indicated possible fitness benefits for U. crassus through combined effects of high intensities of glochidia releases and high survival of released glochidia. The furthered understanding of climate change effects on mussel and host phenology in seasonal environments, potentially inducing temporal mismatches of glochidia release to host availability, is key to mussel conservation.”

Acces the paper here: Evaluating temperature- and host-dependent reproduction in the parasitic freshwater mussel Unio crassus

The research was part of the LIFE project UCforLIFE. Read more about the thick shelled river mussel and related conservation work at the projects homepage: www.ucforlife.se

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Caryn Vaughn (left) asking questions to Lea Schneider (right) during the PhD-defense.

Today Lea Schneider successfully defended her PhD-thesis ”Conservation ecology of the thick-shelled river mussel Unio crassus – the importance of parasite-host interactions” at Karlstad UniversityCaryn Vaughn (University of Oklahoma, USA) was the opponent, and Leonard Sandin (Swedish University of Agriculture), Niklas Janz (Stockholm University, Sweden), and Annie Jonsson (University of Skövde, Sweden) constituted the grading committee (betygskommitté).

Lea Schneiders supervisors during her PhD were Martin Österling and Anders Nilsson from Karlstad University, and Johan Höjesjö from the University of Gothenburg, Sweden. Her work constituted on part of the LIFE-project UCforLife – Målarmusslans återkomst.

The thesis is available here. Contact Lea Schneider for questions and additional information.

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According to tradition, Lea Schneider (center) last week nailed her thesis to the wall, at the entrance to Karlstad University. On the photo are also Martin Österling (supervisor) and Reine Lundin (dean).

On February 24, Lea Schneider, will defend her PhD-thesis ”Conservation ecology of the thick-shelled river mussel Unio crassus – the importance of parasite-host interactions”. In the abstract Lea Schneider writes: ”Unionoid mussels are globally threatened and their conservation requires species-specific knowledge on their ecology and parasite-host interaction. Unio crassus is one of Europe’s most threatened unionoid species and has a temporary obligate parasitic life stage (glochidia) on fish. A lack of suitable hosts is probably a major limitation for mussel recruitment, but host species composition, suitability and availability in time and space have yet to be fully explored. This thesis examines different aspects of the host fish species, including their composition, suitability and ecological importance, in relation to U. crassus, using both field and laboratory studies. The effects of mussel and host density on mussel reproductive potential were considered, as were aspects of evolutionary adaptations between mussels and fish and how climate change may affect their interaction.

The results show that U. crassus is a host generalist, parasitizing a variety of fish species. Host suitability and density, which varied among fish species and rivers, affected the level of glochidia encapsulation, hence mussel reproductive potential, more so than the density of mussels taking part in reproduction. Ecologically important hosts included both highly suitable primary hosts, and less suitable hosts that were highly abundant. Whether or not U. crassus has specific adaptations to its hosts to enhance juvenile transformation remains unclear. No distinct pattern of local adaptation was found, nor was there an effect of host fish presence on the timing of glochidia release by adult mussels. Instead, temperature played a major role, with results suggesting that changes in spring water temperature regimes can cause temporal and spatial mismatches in the mussel-host interaction. This thesis indicates that investigations of local mussel-host interactions help in identifying mechanisms important for unionoid conservation management and prioritization.”

The defense will take place on February 24 at 10:15 in room 1B309 (Sjöströmsalen) at Karlstad University. The frame of the thesis is available online here.

For the defense, Caryn Vaughn (University of Oklahoma, USA) is the opponent, and Leonard Sandin (Swedish University of Agriculture), Niklas Janz (Stockholm University, Sweden), and Annie Jonsson (University of Skövde, Sweden) constitute the grading committee (betygskommitté).

In the afternoon (from 13:30 onwards) the day before the defense (Feb 23), seminars related to the thesis will be given in Room 5F416 at Karlstad University. Here Caryn Vaughn will present on ”Consumer aggregations act as hotspots of ecosystem function and services in rivers”, Niklas Janz on “What is host range?”, and Leonard Sandin on “Evaluation of ecological restoration in Swedish streams – some results from the EKOLIV project”. 

Everyone is welcome to attend both the PhD-defense and the seminars.

Forskare inom NRRV vid Karlstads Universitet ska under de kommande tre åren undersöka ekologiska effekter av utrivningen av en kraftverksdamm, samt hur fisk påverkas av så kallade ”fiskvänliga” turbiner. Forskningen kommer att ske i Mörrumsån (dammutrivning) och i Emån (fiskvänlig turbin). De involverade forskarna är (än så länge) Lutz Eckstein, Anders Nilsson, Olle Calles och Martin Österling och gruppen förväntas undesöka allt från växtsamhällen till fiskars beteende. Projektet finansieras av KK-stiftelsen och är ett samarbete mellan Karlstads Universitet, Uniper, Sveaskog och Power house. Läs mer om projektet på fiskejournalen.se eller på kau.se.

Är du en disputerad biolog som tycker att det här låter intressant? Projektet har utlyst en postdoc tjänst. Läs mer här.

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Freshwater pearl mussels.

The paper ”Heavy loads of parasitic freshwater pearl mussel (Margaritifera margaritifera L.) larvae impair foraging, activity and dominance performance in juvenile brown trout (Salmo trutta L.)”  by Karl Filipsson, Tina Petersson, Johan Höjesjö, John Piccolo, Joacim Näslund, Niklas Wengström, Martin Österling was recently published in Ecology of Freshwater Fish. In the abstract the authors write:

”The life cycle of the endangered freshwater pearl mussel (Margaritifera margaritifera) includes a parasitic larval phase (glochidia) on the gills of a salmonid host. Glochidia encystment has been shown to affect both swimming ability and prey capture success of brown trout (Salmo trutta), which suggests possible fitness consequences for host fish. To further investigate the relationship between glochidia encystment and behavioural parameters in brown trout, pairs (n = 14) of wild-caught trout (infested vs. uninfested) were allowed to drift feed in large stream aquaria and foraging success, activity, agonistic behaviour and fish coloration were observed. No differences were found between infested and uninfested fish except for in coloration, where infested fish were significantly darker than uninfested fish. Glochidia load per fish varied from one to several hundred glochidia, however, and high loads had significant effects on foraging, activity and behaviour. Trout with high glochidia loads captured less prey, were less active and showed more subordinate behaviour than did fish with lower loads. Heavy glochidia loads therefore may negatively influence host fitness due to reduced competitive ability. These findings have implications not only for management of mussel populations in the streams, but also for captive breeding programmes which perhaps should avoid high infestation rates. Thus, low levels of infestation on host fish which do not affect trout behaviour but maintains mussel populations may be optimal in these cases.”

Read the paper here. If you don’t have access to the journal’s content, email any of the authors.

Förra veckan besökte en grupp forskare från NRRV vid Karlstads Universitetet Gnarpsån och Nianån. Båda vattendragen mynnar i Östersjön och kommer vara föremål för ambitiösa dammutrivningsprojekt. Totalt kommer tre reglerdammar och tre vattenkraftverk att rivas ut. Åtgärderna förväntas gynna vandrande fisk såsom havsöring, sik, flodnejonöga och ål men även andra djur- och växtarter lär dra nytta av de öppnade vandringsvägarna och restaurerade habitaten. NRRV och Karlstads Universitet är inblandade i utvärderingen av åtgärderna. Planen är att undersöka dammutrivningens effekter på, bland annat, den vandrande fisken, flodpärlmusslor, bottenfauna och strandvegetation.

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En av dammarna som kommer att rivas ut.

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Habitat som kommer att öppnas upp för vandrande fisk.

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Lutz Eckstein undersöker strandvegetation i området.

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Martin Österling kollar på flodpärlmusslor.

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Dammutrivningen kommer att öppna torrfåran för fisk, bottenfauna och vattenväxter men även påverka omgivande ekosystem.

Under Fiskmarknaden i Luleå tidigare i år, presenterade Johan Andreasson (Hudiksvalls kommun) dammutrivningsprojekten i de båda åarna. Hans presentation finns tillgänglig online här: Dammutrivningen av Nianåns enda kraftverk, erfarenheter och vad som komma skall.

Intresserade barn samlas kring ålakvariet medan Martin Österling och Olle Calles berättar. Foto från Värmlands Folkblad.

Igår presenterades ål och ålforskning för barn i aulan på Karlstads Universitet. Som en del av Barnens universitet berättade Olle Calles och Martin Österling om ålens vandring från Sargassohavet till våra kuster,vattendrag och sjöar, och tillbaka igen. Den kraftiga minskningen av ålbestånden under de senaste årtiondena illustrerades och en ålyngelledare för att leda ålyngel förbi vattenkraftverk byggdes på scen. Tillslut förevisades levande ålar och radiotelemetri-utrustning för intresserade barn. Även Johan Watz, postdoc vid Karlstads Universitet, och Lissie de Groot, Erasmus-praktikant vid universitetet, deltog i arrangemanget.

Lokalpressen var på plats och rapporterade senare om ålen på Barnens universitet:

Värmlands Folkblad: Lärde skolbarn rädda ålar

Nya Wärmlands Tidning: Barnens universitet är tillbaka

Ål på Barnens universitet

Posted by Daniel Nyqvist | Events
barnens

Barn studerar ål under ett liknande arrangemang 2011.

För nionde året presenterar ”Barnens universitet” föreläsare och forskningsämnen på Karlstads Universitet. Under sex måndagar i höst är barn 8-12 år välkommna att träffa forskare på universitetet. Nästa måndagen, den 10 Oktober, klockan 15:00-15:45 är det dags för Olle Calles och Martin Österling, biologer och forskare vid Karlstads Universitet, att presentera ålen. Martin och Olle berättar om upplägget: ”Ålen är en klurig fisk med många hemligheter. Den lever djupt nere i sjöar och hav, men kan faktiskt också klara sig i luft under flera timmar, och klättra uppför lodräta väggar! En annan konstig sak med ålar är att de kan bli väldigt gamla, trots att de är utrotningshotade. Varför är det så? Vi ska lära er mer om ålen och vad man kan göra för att hjälpa till att rädda den.”

Ålen presenteras i Ljungbergsalen, på Karlstads universitet. Barn, föräldrar och andra intresserade är välkomna!