Karl Filipsson, Eva Bergman, Larry Greenberg, Martin Österling, Johan Watz and Ann Erlandsson recently published the paper “Temperature and predator-mediated regulation of plasma cortisol and brain gene expression in juvenile brown trout (Salmo trutta)” in the journal Frontiers in Zoology.

In this study, we tested how temperature and the presence of a cold-water adapted predatory fish (burbot, Lota lota) affected primary stress responses (i.e. cortisol and mRNA levels of stress-related genes) in juvenile brown trout (Salmo trutta). We found that trout had elevated cortisol levels in the presence of burbot, and that stress-related gene expressions varied a lot with temperature. In addition, we found that the predator-induced effects on mRNA levels were temperature dependent for some of the genes. This, together with the directly temperature-mediated effects that we observed in our study, suggest that warming winters can have major impact on primary stress responses in overwintering salmonids, for instance in encounters with predators.

In the abstract of the paper, we wrote that:

“Temperature affects many aspects of performance in poikilotherms, including how prey respond when encountering predators. Studies of anti-predator responses in fish mainly have focused on behaviour, whereas physiological responses regulated through the hypothalamic-pituitary-interrenal axis have received little attention. We examined plasma cortisol and mRNA levels of stress-related genes in juvenile brown trout (Salmo trutta) at 3 and 8 °C in the presence and absence of a piscivorous fish (burbot, Lota lota).

One of the experimental aquaria used for the study.

A redundancy analysis revealed that both water temperature and the presence of the predator explained a significant amount of the observed variation in cortisol and mRNA levels (11.4 and 2.8%, respectively). Trout had higher cortisol levels in the presence than in the absence of the predator. Analyses of individual gene expressions revealed that trout had significantly higher mRNA levels for 11 of the 16 examined genes at 3 than at 8 °C, and for one gene (retinol-binding protein 1), mRNA levels were higher in the presence than in the absence of the predator. Moreover, we found interaction effects between temperature and predator presence for two genes that code for serotonin and glucocorticoid receptors.

We extracted mRNA from the forebrain (telencephalon) of the trout. The picture shows a trout brain after dissection, where the telencephalon is the two upper lobes.

Our results suggest that piscivorous fish elicit primary stress responses in juvenile salmonids and that some of these responses may be temperature dependent. In addition, this study emphasizes the strong temperature dependence of primary stress responses in poikilotherms, with possible implications for a warming climate.”

You can read the paper for free on the journal website, as the paper is published open access through funding provided by Karlstad University.

On Tuesday 25 February, Kalle Filipsson, RivEM PhD student, will give a seminar entitled ”From behaviour to genes: anti-predator responses of brown trout under winter conditions”. The seminar starts at 13.15 in room 5F416, everyone who wants to is welcome to attend the seminar.

This seminar is a practice seminar in preparation for Kalle’s (my) licentiate defense, which will be held Friday 13 March at 10:00. More information about the licentiate seminar will be provided closer to the defense.

Juvenile brown trout (Salmo trutta). Photo: Karl Filipsson
A burbot (Lota lota) in a stream flume at Karlstad University. Photo: Karl Filipsson

Seminars Tuesday 9 October 2018

Posted by Karl Filipsson | Events

A threespine stickleback (Gasterosteus aculeatus), a fascinating animal likely to be mentioned in both talks.

On Tuesday October 9, two seminars will be held at the biology department at Karlstad University.

Adaptive potential and evolutionary responses to climate change: Arctic char and threespine stickleback in GreenlandMichael Hansen, Professor, Aarhus University

Ecological genetics – What’s it about and how can we use it? – Karl Filipsson, NRRV PhD-student, Karlstad University

The seminars will be held in room 5F416 and start at 13:15. Everyone who wants to are welcome to attend the seminars.

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.

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.”

YouTube Preview Image

YouTube Preview Image

 

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.

Förra veckan försvarade Kim Magnus Bærum, vid Universitetet i Oslo, sin doktorsavhandling “Climate-driven population responses of resident brown trout, Salmo trutta, Trends and future projections.”. Eva Bergman från Karlstads universitet var opponent och rapporterar om ett väl genomfört försvar, med en intressant och trevlig diskussion. Som en del av disputationen gav Kim Magnus Bærum en  provföreläsning med titeln: “Freshwater biodiversity in a changing environment; spatial and temporal patterns”.

Salmonid (Atlantic salmon) eggs (photoscienceimage)

Larry Greenberg is currently working on a research project on potential effects of increased winter temperature on brown trout growth and behavior. The research is funded by Karlstad University’s Lecturers and Professors Research Award. Larry describes the project:

“The predicted climate change over the next 65 years will have a major impact on the Earth’s plants and animals. Climate scenarios for Sweden predict that mean annual temperature will increase by 3-5 ° C, with a greater increase in winter than in summer. Because incubation of eggs laid by brown trout and related fishes occurs during winter, the predicted increased winter temperatures may have a major impact on egg development, with far-reaching consequences for fish after they have hatched. The fact that environmental conditions during the egg stage can affect later life stages (juveniles and adults) may seem unlikely, but recent studies have already shown that temperature conditions during egg development can affect growth of juveniles and even reproductive output of adults. As embryonic temperature conditions have been shown to affect growth, one would also expect such conditions to even affect behavior, as behavior and growth are often linked.

For this project, I plan to investigate how an increase in winter temperature conditions during egg development affects the behavior and growth of juvenile brown trout. I will raise fertilized brown trout eggs over the winter at ambient temperature and at 5° C warmer water, and test for subsequent effects on the feeding behavior and personality of juveniles as well as on their growth and metabolic rates.  The research is novel by being the first to investigate whether or not thermal conditions during egg development can affect both the behavior and growth of juveniles.”

The eggs are presently developing under different temperature regimes at Gammelkroppa fish hatchery.