Sebastian Rock recently started his PhD at Karlstad University. Here he writes about his previous work and what he intends to do as a PhD student at Karlstad University:

Well hi there! I’m Sebastian Rock, a new PhD student at NRRV research group at Karlstad University. Originally from the US Virgin Islands, I’ve lived across the US and later, all around Italy as well, as such, I’m hoping to bring a little extra warmth to this cold part of Sweden. Working as a part of the Life Connects project under the supervision of Martin Österling, Olle Calles, Johan Watz and Anders Nilsson (from Lund University), I’ll be working on conservation and reintroduction of highly threatened parasitic freshwater river mussels. I’ll predominantly be focused on the Freshwater Pear Mussel (Margaritifera margfaritifera) and the Thick Shelled Riven Mussel (Unio crassus) in the Skåne region in south Sweden. Where possible I hope to do scientific outreach and education to help raise both the general public interest in the less well-known aquatic fauna as well as the importance of ecologic conservation.

Sebastian with a massive 30+ kg of Laetiporus spp. (aka: Chicken Fungus, Sulfur Shelf) in Maastricht.

I started my academic life like many others as a bachelor student, myself at Maastricht University’s Maastricht Science Program in the Netherlands. Only founded in 2010, it was designed as an open end Liberal Arts and Science program, where students there are encouraged to develop their own interdisciplinary curriculum to better adapt to the modern vastly interconnected research environment. As the son of two Biologists, and as someone intensely interested in anything to do with animals, the apple didn’t fall far from the tree as I focused almost all my attention towards the biological sciences ranging from ecology to psychopharmacology. As part of the program, once a semester, students take part in a month long research project, designed with the intention of not only exposing students to a wide range of academic fields and topics, but also to provide substantial research experience to build future degrees with. Here, I got along with the zoology professor Dr John Sloggett and together organized a series of research projects on the behavioral toxicology of an invasive planarians flatworm species from North America, Girardia tigrina; these projects ultimately evolved in to my BSc thesis.

Petridish full of flatworms with BSc student Nicholas Versé in the background.

From Maastricht, I moved on to a Research Masters degree at Leiden University, also in the Netherlands, where I worked with Drs. Christian Tudorache and Marcel Schaaf at the Institute of Biology Leiden where I was able to apply my interdisciplinary background to the study of stress coping in larval zebrafish. Using Multidimensional reduction techniques, I worked on modeling coping style, the inter-individual differences in behavior (or the animal equivalent of personality) with a more straightforward and concrete measure of gestation time. Over the course of my Masters I continued to design smaller research projects for BSc students as well as working with a local international school to give short seminars and demonstrations of simple scientific projects with wide reaching implications to give them a better idea of, and hopefully inspire them to peruse an education in science.

As a researcher at KAU – NRRV I hope to apply my interdisciplinary education to the study of the effects the parasitic mussels have on their host fishes. In the case of the Pearl Mussel, salmonids, and in that of the Thick Shelled Mussel, predominantly minnows and bullheads. As much of my work will be relating to the reintroduction of these, mostly stationary, endangered parasites, they will need to be reintroduced through their more mobile host fish. As knowledge on the behavioral effects of the parasite on the fish is very limited, I hope to expand it be looking at competition behavior between infested and non-infested fish, as well as other changes in behavior, which may reduce overall fitness. After all, if we kill off all the hosts, that won’t help the parasite any more than doing nothing at all. I hope to include genomic, immunologic and abiotic factors in the conservation efforts with a little help from some multidimensional modeling to stitch it all together.

Away from the office, you can find me either outside, fishing and hunting for mushrooms, or inside building an eclectic collection of reptiles and amphibians in unique enclosures as I experiment with culinary sciences to the sound of a bizarre musical library. Feel free to stop by my office to talk about research, or any of those last three things. If you care to follow any of my sometimes semi-science related stuff you find me on Instagram @srock456.

Cheers and see you around!

Marleen Schwarze from the Leuphana University in Lüneburg, Germany, studied for a year at Karlstad University as an exchange student. Afterwards she did an internship with NRRV. Here she writes about her experiences this summer:

“Since my bachelor program Environmental and Sustainability Studies includes one year abroad, I spent the fall 2019 and spring semester 2020 at Karlstad University. During that time I got a first impression of the biology department. The interesting courses I had here awakened my interest in fresh water ecology. Also, Karlstad became a new home for me, so I was happy to be able to extend my stay and complete the study experience in Sweden with a practical internship for three months.

My main motivation was to get an insight into scientific procedures and to gain research experience. Therefore, I was glad to spend a lot of time both in the lab and in the field and also, that it was even possible to do this internship, despite the pandemic.

I worked in two research projects, which expanded my knowledge on plant and invertebrate taxonomic identification, riparian zones and research methods. One project examines the impacts of hydropeaking caused by hydropower plants on riparian zones and the benthic fauna. The fieldwork included sampling of plants, invertebrates, chlorophyll measurements, as well as abiotic such as water quality (N, P and DOC) and geological measurements. The other project looks at plant dispersal in regulated and restored rivers. We conducted vegetation surveys along a river that is regulated for hydropower purposes (Umeälven) and a river that has been restored from its channelized form (Vindelälven), and their tributaries. Further, we took soil samples to analyse soil nutrient contents (C, N and P).

Someone said that fieldwork is the best strategy for keeping social distance. After almost eleven weeks of being every day outside, I can say that it is totally true. This summer I got to know more plant species than people and I dedicated more time to macroinvertebrates than to friends. We conducted the fieldwork at different rivers in Värmland, Örebro, Dalarna, Västra Götaland and Västmanland County, as well as in Västerbotten County. Hence, this internship was not only an intense learning experience which enriched my studies, but also an opportunity to see a lot of beautiful places during summer in Sweden.

I am grateful to Lovisa Lind who coordinated my internship and all the other researchers at the KAU biology department, in particular Jacqueline Hoppenreijs, Johan Watz, Lutz Eckstein and John Piccolo. Additionally, I am glad about the great teamwork with my fieldwork collegues and fellow students Andreas Vernby, Mattias Hansson and Andreas Marklund. Further, my thanks go to the International Offices, both in Karlstad and at my home university in Lüneburg, for helping me with the administrative process and support to get Erasmus+ funding which made this internship possible for me.”

Lutz Eckstein, professor at Karlstad University, together with Yves Klinger, David HorlemannAnnette Otte and Kristin Ludewig recently published the paper Germination of the invasive legume Lupinus polyphyllus depends on cutting date and seed morphology in the journal NeoBiota. The paper is accessible open access on the journal website, or you can read a summary of the paper below:

In semi-natural grasslands, mowing leads to the dispersal of species that have viable seeds at the right time. For invasive plant species in grasslands, dispersal by mowing should be avoided, and information on the effect of cutting date on the germination of invasive species is needed. We investigated the germination of seeds of the invasive legume Lupinus polyphyllus Lindl. depending on the cutting date. We measured seed traits associated with successful germination that can be assessed by managers for an improved timing of control measures. Germination patterns were highly asynchronous and differed between seeds cut at different dates. Seeds cut early, being green and soft, tended to germinate in autumn. Seeds cut late, being dark and hard, were more prone to germinate the following spring, after winter stratification. This allows the species to utilize germination niches throughout the year, indicating a bet-hedging strategy.

Lupine seeds used in the study

Seed color and the percentage of hard seeds were good predictors of germination percentage. Managers should prevent the species from producing black and hard seeds, while cutting plants carrying green and soft seeds appears less problematic. Furthermore, germination patterns differed between experiments in climate chambers and in the common garden, mainly because germination of dormant seeds was lower in climate chambers. We propose that more germination experiments under ambient weather conditions should be done, as they can give valuable information on the germination dynamics of invasive species.

Johan Watz, David Aldvén, Antonis Apostolos Brouziotis, Niclas Carlsson, Eirini Karathanou, Kristine Lund‐Bjørnås, Gustav Lundqvist, Martin Österling, John J. Piccolo and Olle Calles recently published the paper “Social behaviour of European grayling before and after flow peaks in restored and unrestored habitats” in the journal River Research and Applications.

In the abstract of the paper the authors write:

“Cost‐effective implementation of fish‐friendly hydropower flow operation and habitat restoration measures require an understanding of their effects on fitness‐related behaviours of stream fish. Here, we investigated how changes in flow and bottom structure influence the social behaviour of European grayling, using large experimental flumes (700 L s−1), with and without added boulders (i.e., restored and unrestored habitat). Grayling increased their distance to nearest neighbour at the start of flow ramping up and after a flow peak compared to stable base flow. At the start of ramping up the flow, grayling made less position changes (movements >1 m) than at stable base flow and after a flow peak. In the unrestored habitat, the proportion of time grayling spent actively swimming was lower before a flow peak than it was both at the start of ramping up the flow and after the peak, an effect not found in the restored habitat. In addition, we compared two static flows, and habitat restoration mediated their effect on distance to nearest neighbour. Grayling in the restored habitat were positioned closer to each other in the low (~10 cm s−1) than in the intermediate static flow (~40 cm s−1), whereas in the unrestored habitat, grayling showed the opposite pattern. Moreover, grayling reduced their number of position changes in the intermediate static flow, which was reflected by a reduction in active swimming. Stomach analysis after the trials revealed that foraging success was higher in variable than in the stable flow treatment. These results show that flow magnitude, flow changes and instream structure play important roles in the behaviour of stream fishes.”

The paper is available open access on the journal website.

Johan Watz (left), together with Eirini Renata Karathanou and Antonis Apostolos Brouziotis.

On Tuesday 2 June Sanna Stålhammar at the Lund University Centre for Sustainability Studies will give a seminar entitled “Reconnecting with nature through concepts: On the construction of values in the ecosystem services paradigm”.

The seminar starts at 13:15 and will be held online and streamed on Zoom. The seminar is open for everyone who wants to attend. We will not distribute the zoom link to the seminar publicly online. If you want to attend the seminar, contact John Piccolo (, and he will send you a zoom link so that you can participate.

On Tuesday 26 May Roman Motyka, NRRV PhD student, will give a seminar entitled “The role of behavior and habitat use in conservation biology of the European eel (Anguilla anguilla). During this seminar, Roman will present his plans for his PhD project.

The seminar starts at 13:15 and will be held online and streamed via the video communication system Zoom. Everyone who wants to attend the seminar are welcome to do so. We will not distribute the zoom link to the seminar publicly online. If you want to attend the seminar, contact Roman ( or Olle Calles (, and they will send you a zoom link so that you can participate.

Roman Motyka (right) and Tobias Knieps (left) with some eels in a net.

As a member of the European consortium RIBES (River flow regulation, fish Behaviour and Status), the River Ecology and Management research group at Karlstad University invites applicants to three PhD positions on fish migration and passage in regulated rivers. In addition to the three PhD positions in Karlstad, RIBES also announces 12 more PhD positions in Belgium, Estonia, Germany, Italy and the UK as part of the same network.

Read more about the PhD positions and how to apply here!

Last application date is 31 May 2020.

To be eligible for one of the PhD positions in Karlstad, candidates cannot have resided in Sweden for 12 months or longer in the 3 years immediately before the recruitment date.

For more information about RIBES, check out our website!

River Klarälven in Värmland, Sweden

Today (Tuesday 7 April) Raviv Gal, NRRV PhD-student, will give a seminar entitled Mussels and ecosystem functioning in streams. The Seminar is held online via the video conference system zoom.

You can follow the seminar by clicking here.

The seminar starts at 13:15, everyone who wants to is welcome to attend the seminar.

Freshwater pearl mussels (Margaritifera margaritifera) in the River Vasslabäcken.

On Thursday 26 March, Kristine Lund Bjørnås, NRRV PhD-student, will defend her licentiate thesis “Modeling Atlantic salmon and brown trout responses to river habitat alteration”. The defense starts at 10:00. Asbjørn Vøllestad, Professor at the University of Oslo, is the opponent for Kristine’s defense.

Kristine’s defense will be held as an online meeting on Zoom (a video communication system commonly used by universities). You should be able to follow Kristine’s defense using this link:

The defense will also be streamed live on a bigscreen in lecture hall 1B309 (Sjöströmsalen) at Karlstad University, and everyone is welcome to watch the defense from the lecture hall. Please note that Kristine and the opponent will not be in the lecture hall.

On Friday 13 March, Kalle Filipsson, NRRV PhD-student, will defend his (my) licentiate thesis. The thesis has the title ”From behaviour to genes: anti-predator responses of brown trout (Salmo trutta) under winter conditions”. The defense will be held in room 1B309 (Sjöströmsalen) at Karlstad University, and starts at 10:00. Stefán Óli Steingrímsson, Professor at Hólar University, Iceland, is the opponent. The defense is open for everyone who wishes to attend.

Kalle’s licentiate thesis, nailed to one of the “theses trees” at the Biology Department at Karlstad University.
Three juvenile brown trout (Salmo trutta), doing trout stuff in a stream flume at Karlstad University.