River Rottnan in winter

Johan Watz, Olle Calles, Niclas Carlsson, Teemu Collin, Ari Huusko, Jörgen Johnsson, Anders Nilsson, Johnny Norrgård and Daniel Nyqvist recently published the paper “Wood addition in the hatchery and river environments affects post-release performance of overwintering brown trout” in the journal Freshwater Biology.

In the abstract, the authors write:

“1. Habitat structural complexity affects the behaviour and physiology of individuals, and responses to the  environment can be immediate or influence performance later in life through delayed effects.

2. Here, we investigated how structural enrichment, both pre-release in the hatchery rearing environment and post-release in the wild, influenced winter growth and site fidelity of brown trout stocked into side channels of a regulated river.

3. Experiencing structural enrichment in the rearing environment during 3 months in autumn had no pre-release effect on growth, but a delayed positive effect after release during the subsequent winter. Moreover, trout recaptured in wood-treated sections of the side channels had grown more than trout recaptured in control sections. Wood enrichment in the side channels also increased overwinter site fidelity.

Johan Watz at the field site.

4. These results show that adding structure during a relatively short period may alter growth trajectories, and adding wood to side channels is a cost-effective method to enhance winter habitat carrying capacity for  juvenile salmonids in regulated rivers.”

Access the paper here.

Teemu Collin tracking trout at the field site.


Dead wood in a side channel of the river.


River Rottnan.

Lovisa Lind recently started her position as Associate Professor in landscape ecology at Karlstad University and the NRRV research group. Here she presents her scientific background and research interests:

“Hello, I’m Lovisa Lind and I am very excited to join such a great research group. For the past years, I have been working enthusiastically as an ecologist with a specific focus on riparian, aquatic and winter ecology, and hydrology. My research strategy is to take a basic research approach to answer ecological and management questions with a focus on riparian zones. More specifically, I study interactions between terrestrial and aquatic processes, and how species diversity, distribution of organisms and ecosystem services respond to such interactions. I apply these research findings to current land use problems to develop best management practices to protect and optimize ecosystem services in the landscape.

My PhD work combined fundamental and applied questions. My thesis describes mechanisms structuring riparian vegetation along streams and rivers in relation to river ice formation, as well as the spatial variability of ecosystem services provided by riparian zones in boreal Sweden. As scientists predict climate change to influence ice formation, snow cover and winter temperatures in cold regions there is great need to study its influence on the river ecosystems. Hence, my research has provided novel evidence that different types of ice formation in streams and rivers influence the species diversity in the riparian zone, and that future changes in climate might decrease the river ice season and therefore affect the riparian flora. In addition, I have collaborated with a Norwegian hydrologist to complement my ecological understanding with hydrological processes during winter. This collaboration resulted in a simple model over river ice formation, which can be beneficial for managers in cold-water regions. Working on a large spatial scale also has provided me with a very thorough river system knowledge and I was therefore involved in several restoration projects. The Vindel River LIFE project, which was an EU funded restoration project involved many different stakeholders and opened up for new findings and new questions regarding river restoration. I have also worked on identifying the channel topography that is optimal for restoration efforts to sustain the biodiversity that is typical for boreal streams.

In 2015, I joined the Jefferson Project at Rensselaer Polytechnic Institute (RPI) for a one-year postdoctoral position. The Jefferson project is a collaboration between RPI, IBM and the FUND for Lake George and combines data analytics with experimentation to understand how human activity affects Lake George. The goal of the Jefferson Project was to revolutionize the way we research, monitor, conserve, and interact with aquatic ecosystems. By combining cutting-edge sensing technology (e.g., underwater sensors, weather stations) with state-of-the-art computing and visualization power, we aimed to fast-forward our understanding of lake ecosystems and to make Lake George a global model for ecosystem understanding and protection. My role in this large project was to investigate the effects of road salt usage and eutrophication on aquatic ecosystems.

After the postdoctoral position at RPI, I joined Hjalmar Laudon´s lab at SLU, Umeå for another postdoctoral position. There I focused on how to optimize buffer zones in agricultural landscapes by conducting a meta-analysis. One of the goals of my project was to provide landowners and managers with guidelines on how to adjust buffer zones in their catchment in order to sustain resilient landscapes. In the meantime, I was in charge of two projects funded by HaV (The Swedish Agency for Marine and Water Management) regarding buffer zones in agricultural landscapes.

Thereafter, I once again joined the Landscape Ecology Group at Umeå University. The research involves various aspects of watershed science and management. Mainly, I study how the position in the landscape influences the biological variation in streams and riparian zones. I also explore the role of different process domains (lakes, rapids, slow-flowing reaches) in determining the species composition in restored sites further downstream. I also address how anthropogenic disturbance within a catchment or landscape influences the restoration success. Within a catchment or a landscape the anthropogenic influence on the rivers and streams varies with for example the number of and closeness to roads, and agricultural or forestry land-use. Therefore, I will determine the degree of anthropogenic disturbance by using GIS and field visits to restored river segments and thereafter connect it to the species richness and diversity of riparian and instream vegetation.

In my research, I have worked with ecology, hydrology, restoration ecology, food webs, river ice and biogeochemistry, and therefore gained a holistic understanding of watershed science and management. Even though I am enthusiastic about conducting fundamental and empirical research, I always want to link my findings to applied questions. Applying research findings to today’s nature management is an important part of being a scientist and I am keen to creating collaborations with managers and companies as well as being involved in teaching and communication of research findings.”

Find out more about Lovisa and her research on her website.

Anissa Bengattat (middle), together with Rachel Prokopius (left), exchange student from Northern Kentucky University, and Elio Bottagisio (right), master student from France, doing fieldwork in the stream Rannån.

In April 2018, Anissa Bengattat from France visited Karlstad University and did an internship with NRRV. Here she writes about her weeks in Sweden.

Hej där!

I’m Anissa Bengattat, a French student in HND ‘Management and Protection of Nature’ in a town located in France, named Vic-en-Bigorre. As a practical training, I have been doing my three-weeks internship at Karlstad University with the Ecology and Conservation Biology program.           

During these weeks, I have learned vastly about different aspects of  freshwater ecology.  My main mission has been to collect, sort, identify and archive macro-invertebrates, collected in the field, in the freshwater stream Rannån. With the help of Richard Durtsche, guest-professor from the USA, and his student Rachel Prokopius, I managed to follow a project from the start to the end.

I have tested digital imaging of the identified invertebrates, and I have seen the calorimetry process, used in order to make links with the fishes‘ energetics consumption.

 I have also been in the stream aquarium laboratory to participate in some interesting experiments. First, I have learned about the whole fishes respirometry system, made up by R. Durtsche, where we studied oxygen consumption for brown trout. Then, I’ve learned about Karl Filipsson’s experiments about climate change effects on predation on brown trout. Their behaviour, linked to the temperature and the presence or not of burbot, and how to identify it scientifically by extracting trouts‘ RNA.

 Finally, I have attended master classes for these three last weeks, which consolidated my idea to do a bachelor after my HND, and then a master, if possible, abroad.

This internship wasn’t only about studies to me, it was also about meeting new people in another country with a different way of living, and a different way of teaching. It was about making concrete links in my mind between how much I still have to learn, and how to develop into an accomplished scientist.

Thanks to John Piccolo who set up my internship, thanks to the international office of Karlstad university which helped, and thanks to Elio Bottagisio, the French master student who told me about this program. And finally, thanks to all the people who taught me things during this internship,  Richard Durtsche, Rachel Prokopius, Olle Calles, and Karl Filipsson. I hope to come back.

Burbot, Lota lota

On Tuesday 3 April 2018, Karl Filipsson, PhD student at Karlstad University, will give a talk titled “The effects of temperature and light conditions during winter on antipredator responses of juvenile brown trout against burbot”. The seminar will start at 13:15 in room 5F416 at Karlstad University. Everyone is welcome to attend the seminar.

Although most fieldwork is carried out in warmer seasons, members of the NRRV research group also go out in winter to collect information and samples for their research. Here, Richard Durtsche, visiting professor from Northern Kentucky University, writes about a field excursion that took place last week:

Andrew Harbicht, Post-Doc at Karlstad University (front) and Richard Durtsche, visiting professor from Northern Kentucky University, (back) at the field site.

“As part of a study on the energetics in natural food sources available to Salmonid fishes (trout, salmon, grayling, etc.), we have been sampling the macroinvertebrates in streams that connect to the Klarälven (Clear River) this past fall and now this winter. These investigations will focus on an increase in the accuracy of macroinvertebrate body size measurements taken with digital imaging and an increase in the accuracy of dry mass measures using an ultramicrobalance, newly acquired by Kau Biology. Energetic (caloric) content will also be determined for the different macroinvertebrate taxa. The three target macroinvertebrates groups for this study include mayflies (Ephemeroptera), caddisflies (Trichoptera), and stoneflies (Plecoptera). These are major prey items for all life history stages of Salmonid fishes, and are often used as indicators of stream health in aquatic environmental assessment due to their sensitivity to pollutants and anthropogenic impacts. Results of this study will be useful in developing energetic models of fish foraging for management of fish population and river/stream conditions.

The team that braved the cold winter conditions and moderate snow levels on January 29th included: Richard Durtsche (NRRV visiting professor from Northern Kentucky University), Rachel Bowes (NRRV Post-Doc), Andrew Harbicht (NRRV Post-Doc), and Rachel Prokopius (exchange student from Northern Kentucky University). The stream that we were investigating was located just south of Ransäter. The water was flowing rapidly, and we initially decided to check out the stream conditions on the downhill (east) side of highway 62 to look for sampling sites. There was knee deep (or more) snow to ford before coming to forest cover where moving was easier despite many treefalls. As the streamflow was fast and the water level high, there were no safe locations to sample. So we headed west of highway 62, just off the access road. There we found good sampling habitat just downstream of a large pool that ran under a bridge on that road.

Rachel Prokopius, exchange student from Northern Kentucky University, and Richard Durtsche, measuring the stream width and flow rates.

One of the first things we did at waterside, was to collect physicochemical measures of the water conditions. These included: temperature, pH, conductivity, and dissolved oxygen. We also measured the flow volume of water by measuring the width of the stream, and then taking the depth and flow rates every 50 cm across the stream. Water temps of 1.4°C and the tingle of cold penetrating our waders told us that today was not a good day to fall in the water. After we crossed the fast-flowing stream, we found several relatively shallow areas where we could sample invertebrates. We made a series of kick seine samples from different parts of the stream shallows to dislodge and collect invertebrates from the stones and substrate. 

It was definitely a group effort to kick stones and stream bottom, brush rocks to knock off invertebrates to be carried with stream flow into the seine, and then wash the samples into a collecting bucket. While we thought we might have limited luck, we in fact did extremely well with collecting a range of macroinvertebrates and large quantities of many of those taxa. There will be a good share of macroinvertebrate sorting and measuring upon return to the laboratory.”

Rachel Prokopius, Rachel Bowes, Post-Doc at Karlstad University, and Andrew Harbicht sampling invertebrates using a kick seine.


The team at work in the stream.


Richard Durtsche at the field site.


Close-up photo of a stonefly (Plecoptera) larva.



Karl Filipsson, PhD-student at Karlstad University.

Karl Filipsson has recently joined the NRRV-research group. Here he writes about his previous work and what he intends to do as a PhD-student at Karlstad University:

My name is Karl Filipsson and I recently started my PhD in the River Ecology and Management Research Group (NRRV) at Karlstad University, where I am going to study the winter ecology of stream fishes in relation to climate change. I have a master’s degree in biology from the University of Gothenburg, with focus on aquatic and evolutionary ecology. Although I have a broad interest in fish ecology and behavior, I have developed a special interest for fish inhabiting streams. In my master project I studied the effect of parasitic freshwater pearl mussel (Margaritifera margaritifera) larvae on brown trout (Salmo trutta). The project mainly examined behavioral responses in the host fish, but growth and cardiorespiratory parameters were measured as well.

In my PhD I will use an experimental approach to look at the consequences of warmer winters on predator-prey interactions and early life-history performance in stream fishes. I will use brown trout and burbot (Lota lota) as model species. River ecosystems and associated fish populations have a significant role in providing important ecosystem services. Therefore, it is of great importance to acquire knowledge on the winter ecology of stream fishes under climate change. Hopefully, results from this project will not only elucidate how stream fishes are adapted to winter conditions and respond to environmental change, but will also provide information for stakeholders and decision makers on how to manage fish populations and stream ecosystems in a future influenced by global climate change.

In addition to research, I have a great interest in scientific outreach. I have previously been working at the science center Universeum in Gothenburg and as scuba diving guide, and I am very keen on taking on the challenge to communicate research to the broader public and to be teaching in higher education.”

Some of Karls previous work on the interaction between juvenile brown trout and frehswater pearl mussel larvae is published in the scientific articles Encystment of parasitic freshwater pearl mussel (Margaritifera margaritifera) larvae coincides with increased metabolic rate and haematocrit in juvenile brown trout (Salmo trutta) and Heavy loads of parasitic freshwater pearl mussel (Margaritifera margaritifera L.) larvae impair foraging, activity and dominance performance in juvenile brown trout (Salmo trutta L.).


fiskkauKarlstad Universitet skriver om NRRV:s forskning om temperaturens betydelse under embryoutveckling hos vandrande fiskarters livscykel. I artiklen, med titeln Nordiskt samarbete ger forskningspengar skriver de:

“Temperaturens betydelse under embryoutveckling hos vandrande fiskarters livscykel ska undersökas av forskare från Norge, Danmark och Sverige. Från Karlstads universitet är Larry Greenberg, professor i biologi på NRRV, Naturresurs rinnande vatten, ansvarig för studierna kring olika aspekter av fiskens beteende.

Det är den ökade temperaturen orsakad av global uppvärmning, särskilt under vinterhalvåret, som i våra nordiska vatten kan ha stor påverkan på fiskens livscykel. Detta kan vara särskilt viktigt för fiskar som lägger övervintrande ägg, som laxartade fiskar gör.

– En tidigare studie har visat att med samma mängd mat växer fisken som ung snabbare om deras ägg hade utsatts för en höjning på vattnet med 5 grader jämfört med de normala vinterförhållandena, säger Larry Greenberg. Detta kan leda till att fisken vandrar ut i en yngre ålder, vilket kommer att testas inom detta projekt.

Det här kan också ändra fiskens personlighet och det forskarna bland annat ska studera är om fiskarna blir blygare och mindre aggressiva vid en temperaturhöjning av vattnet under äggstadiet. Dessutom kommer forskarna att undersöka om en miljöförändring, som höjda temperaturer på vintern leder till så kallade epigenetiska förändringar, det vill säga förändringar i hur mycket eller hur lite olika gener uttrycks.

Det Norska forskningsrådet ger drygt sex miljoner kronor till det nordiska samarbetsprojektet som börjar 2017 och avslutas 2020.”

Läs mer om Larry Greenberg’s forskning om vintertemperaturens effekt på fiskars utveckling, fysiologi och beteende i blogg-artikeln: Early environmental effects on behavior and growth: Atlantic salmon in an altered climate.

Larry Greenberg, professor within the River Ecology and Management research group at Karlstad University, is currently studying how increased winter temperatures may affect Atlantic salmon development and subsequent behavior and physiology. Here he describes his research, and shares two videos (one in autumn temperature and one in summer temperature) used to measure (count) ventilation rates on Atantic salmon parr:

“Embryonic temperature conditions are expected to affect an organism’s behavior, as behavior is linked to traits such as metabolic rate and growth. Examining the effects of embryonic temperature is particularly relevant in today’s society as unprecedented rates of climate change are predicted to occur during this century, with a larger temperature increase expected in winter than in summer. Hence, climate change will most likely have large effects on ectotherms (cold-blooded animals) that overwinter their eggs, as is the case for salmonid fishes. The aim of this project is to study the effects of water temperature during the egg stage on the behavior, growth and metabolic rate of juvenile Atlantic salmon.

When it concerns metabolic rates, I hypothesized that elevated temperature during the egg stage will result in reduced standard metabolic rates for juvenile brown trout. Instead of measuring metabolic rates, I have measured breathing rates (ventilation rate), which has been shown to be correlated with metabolic rates. This was done in darkness when breathing rates are lowest, using an infrared-sensitive camera. The two film clips below show two different fish, both of which were raised at cold ambient water temperatures as eggs. One fish was filmed in 7 oC water and the other at 18 oC water.”

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A juvenile brown trout in the experimental flume.

Johan Watz, postdoc at Karlstad University, recently published the scientific article “Stress responses of juvenile brown trout under winter conditions in a laboratory stream” in the journal Hydrobiologia. In the abstract he writes: “Winter can be a challenging period for fish in northern temperate rivers and streams, particularly in those that are channelized, structurally simple or regulated by, for instance, hydropower. In these systems, dynamic sub-surface ice formation commonly occurs and stable periods with ice cover may be short. Under these adverse conditions, access to shelters has been shown to be an important factor that influences overwinter survival, and exclusion from shelters by anchor ice may cause stress. Here, stress responses of juvenile brown trout under simulated winter conditions in an artificial stream were studied. Trout were subjected to three treatments in which the trout (1) were excluded from an instream wood shelter, simulating the effects of anchor ice, (2) had access to the shelter or (3) had surface ice cover in addition to the shelter. There was a positive correlation between ventilation frequency and plasma cortisol concentration. Trout without access to shelter had 30% higher ventilation frequency than trout with instream shelter and surface ice, but no differences in cortisol concentration or stress colour were found between the treatments. River regulation that reduces surface ice and increases anchor ice formation may lead to increased stress and consequently reduce overwinter survival rates.”. 

Access the paper here: Stress responses of juvenile brown trout under winter conditions in a laboratory stream.

A PhD-position in the field of global climate change, as it relates to the ecology of stream fishes in winter, is now open for applicants at Karlstad University. The position is a full time position for 4 years within the River Ecology and Management (NRRV) group at the Department of Environmental and Life Sciences. Read more about the position on kau.se.

As advertised previously, NRRV also has two openings for full-time post-doctoral research fellows. One position is in the field of stream-riparian ecology with focus on the reciprocal interactions and linkages between aquatic and terrestrial habitats. The other position is on river connectivity with focus on rehabilitation, management and development strategies. Read full post-doc position announcements here: Post-doctoral Research Fellow in Aquatic-Terrestrial Linkages and Post-doctoral Research Fellow in Ecology of River Connectivity.