On 28 May (tomorrow), Martin Österling, Associate Professor at Karlstad University, will give a seminar titled:

“The genetic structure of mussels with complex life cycles and its relation to host fish migratory trait and density.”

The seminar starts at 13:15 in room 5F416 at Karlstad University. Everyone who wants to are welcome to attend the seminar.

Two papers from NRRV were recently published in the journal Animal Conservation. The first paper presents a field study on how sedimentation affects brown trout (Salmo trutta) fry emergence in relation to freshwater pearl mussel (Margaritifera margaritifera) recruitment. The second paper presents a combined field and laboratory study on passage solutions for upstream-migrating eels (Anguilla anguilla).

 

Sedimentation affects emergence rate of host fish fry in unionoid mussel streams

– Martin Österling

 

In the abstract, the author writes:

“Free-living, sympatric sedentary life stages of hosts and parasites are often adapted to similar environmental conditions. When the environment where these life stages occur is disturbed, both species can decline, causing strong negative effects on the parasitic species. For the highly threatened unionoid mussels with their larval parasitic life stage on fish, habitat degradation may simultaneously affect the conditions for the sedentary host fish eggs and the juvenile mussels in the sediment. This study provides novel information on the effect of sedimentation on the emergence rate of yolk sac fry, and its relation to mussel recruitment in two drainage basins, and is exemplified by the brown trout Salmo trutta, host fish for the threatened freshwater pearl mussel Margaritifera margaritifera. The results imply that turbidity and sedimentation can reduce the survival of trout eggs and yolk sac fry emergence rate regardless of trout strain and drainage basin. The results further suggest that low yolk sac fry emergence rates reduce the potential for mussel infestation and recruitment. The results indicate a year round negative effect of sedimentation, having strong and combined direct and indirect effects on juvenile mussel recruitment. Conservation measures that reduce anthropogenic sediment transportation into streams are a key factor for the conservation of mussels and their host fish.”

Access the paper here, or contact the author.

 

Climbing the ladder: an evaluation of three different anguillid eel climbing substrata and placement of upstream passage solutions at migration barriers

– Johan Watz, Anders Nilsson, Erik Degerman, Carl Tamario and Olle Calles

 

In the abstract, the authors write:

“Conservation programmes for endangered, long-lived and migratory species often have to target multiple life stages. The bottlenecks associated with the survival of juvenile anguillid eels migrating into inland waters, the survival and growth of the freshwater life stage, as well as the recruitment and survival of silver eels, migrating back to the ocean to spawn, must be resolved. In this study, we focus on the efficiency of passage solutions for upstream-migrating juveniles. Such solutions can consist of inclined ramps lined with wetted climbing substrata. We evaluated different commonly used substrata in a controlled experiment, recorded eel behaviour at the entrance of the ramp with infrared videography and validated the experimental results at a hydropower dam, where we also investigated the effects of ramp placement on performance. In the experiment on eel substratum selection, 40% of the eels passed in lanes with studded substratum, whereas only 21 and 5% passed using open weave and bristle substrata respectively. Video analysis revealed that the studded substratum attracted more approaches and initiated climbs than the other substrata, but once a climb had been initiated, passage success rates did not differ between substrata. Eels using the studded substratum climbed 26% faster than those using the bristle substratum and almost four times as fast as those climbing in the open weave. The superior performance of the studded substratum was supported by data from the field validation. Moreover, ramps positioned by the bank with low water velocities caught the most eels, but proximity to the dam had no effect on performance. To strengthen the European eel population, more juveniles need to reach their freshwater feeding grounds. A critical step to achieve this increase is to equip upstream passage solutions with suitable substrata and to optimize ramp placement at migration obstacles.”

Access the paper here, or contact any of the authors.

Forskare i NRRV har under hösten påbörjat ett projekt inom ett för forskargruppen helt nytt ämnesområde. Det handlar om rörelsemönster hos den spanska skogssnigeln, även kallad mördarsnigel. Mördarsnigeln är en ovälkommen gäst i mångas trädgårdar, där den kan orsaka stor skada genom att äta rent i odlingar och blomsterrabatter. Det är en främmande art i Sverige, som mest troligt har kommit hit när ägg följt med plantor, jord, krukor och annan trädgårdsutrustning.

Frågor om sniglarnas spridningsmönster och koloniseringsförmåga när de väl har kommit till ett område skulle kunna besvaras med hjälp av studien. Till en början diskuterades sniglarna under en fikarast på universitetet, sedan följde att Johan Watz (projektledare) med flera på Karlstads universitet sökte och fick pengar av Kungliga Skogs- och Lantbruksakademien för att genomföra studien.

Nu har ca 50 mördarsniglar i en trädgård i Karlstad märkts med små chip (så kallade pit-tags, samma typ av märkning som används i forskningen om fisk), så att sniglarna kan pejlas och deras rörelsemönster och levnadsvanor studeras.

Tidningen Värmlands folkblad (VF) skrev om projektet måndag 1 oktober, som på flera platser i Karlstad tog plats på löpsedlarna.

Även SVT uppmärksammade studien 3 oktober, och reportaget når du genom att trycka här.

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.

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.

 

Lea Schneider, Anders 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.

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

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 University. Caryn 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.

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.