NRRV Research Projects

Ecosystem Effects of Dam Removal in Inland Waters

Dam removal can cause major changes in ecosystem processes in rivers and lakes. This project uses a large-scale replicated experimental design to quantify the effects of dam removal on nutrient status, biomass of phytoplankton and zooplankton, aquatic vegetation, crayfish and fish, mercury concentrations in predatory fish, and interactions among different components of the food web. The research will generate new knowledge about ecosystem processes in regulated inland waters, providing the scientific basis needed to assess the environmental benefits of dam removal.

Project period: 2022–2024
Funding: Swedish Energy Agency (HåVa – Sustainable Hydropower)
Contact: Johan Watz (johan.watz@kau.se)

Optimised Fish Passage Solutions for European Eel

Hydropower is a renewable and flexible source of energy but fragments river systems. Restoring connectivity requires effective upstream and downstream passage solutions for all naturally occurring fish species. Existing mitigation measures have primarily been designed for salmonids, while knowledge of their effectiveness for other species remains limited. The European eel is critically endangered and a high conservation priority. Its body shape and behaviour differ considerably from those of salmon, meaning that passage solutions suitable for both species are likely to benefit most migratory fish in Sweden. Fish passage efficiency depends on both species- and individual-specific responses to hydrodynamic conditions. This project investigates the importance of individual variation and hydrodynamics at low-sloping guidance racks and eel passes to optimise fish passage while maintaining hydropower production.

Project period: 2022–2024
Funding: Swedish Energy Agency – Sustainable Hydropower (HåVa)
Contact: Olle Calles (olle.calles@kau.se)
Collaborating partners: Lund University, University of Gothenburg, Politecnico di Torino (Italy), and Vattenfall.

Ecological Status of Riparian Habitats in Relation to Winter Hydropeaking

The project aims to improve understanding of how hydropeaking affects ice dynamics and biological communities in boreal rivers. It will also develop guidelines for flow and water-level conditions needed to maintain healthy riparian vegetation, an important indicator of habitat quality.

Hydropower provides almost half of Sweden's electricity generation and is expected to become even more important as society transitions towards a fossil-free energy system. However, hydropeaking can reduce the diversity and abundance of riverine fish, aquatic invertebrates and riparian plants. There is currently limited knowledge about which aspects of hydropeaking are most harmful to different groups of organisms and ecological processes, making it difficult to develop effective mitigation measures. Climate change adds further challenges by altering flow regimes and increasing the frequency of extreme flow events.

Project period: 2023–2027
Funding: Swedish Energy Agency and Energiforsk AB through the Competence Centre for Sustainable Hydropower (SVC)
Contact: Lutz Eckstein (lutz.eckstein@kau.se)
Collaborating partners: Umeå University (Roland Jansson and Birgitta Malm Renöfält)

Evidence-Based Control and Monitoring of the Invasive Garden Lupine Along Species-Rich Road Verges

The project aims to improve ecosystem functions and ecosystem services along species-rich road verges and within green infrastructure through evidence-based control and monitoring of invasive plant species at the landscape scale. The main objective is to develop a phenology-based mowing regime optimised for controlling the invasive garden lupine (Lupinus polyphyllus).

Project period: 2021–2025
Funding: Swedish Transport Administration (Trafikverket)
Contact: Lutz Eckstein (lutz.eckstein@kau.se)

The Riparian Zone in a Changing World

This project focuses on riparian vegetation in boreal ecosystems, the ecological processes that shape these plant communities, such as seed dispersal, and how these processes are influenced by human activities. Geological and hydromorphological factors are also considered, with the overall aim of improving both fundamental understanding and conservation of riparian ecosystems and their plant communities.

Project period: 2019–2024
Funding: NRRV (internal funding, Karlstad University) and RivEM (internal funding, Karlstad University)
Contact: Jacqueline Hoppenreijs (jacqueline.hoppenreijs@kau.se)

Invasive Slugs in Sweden

The aim of this project is to develop new methods for studying invasive slug species in Sweden and to describe and compare their movement ecology, dispersal and reproduction. This knowledge will contribute to reducing the damage caused by invasive slugs and support more effective management of their spread.

Project period: 2018, 2020–2022
Funding: Royal Swedish Academy of Agriculture and Forestry (KSLA)
Contact: Johan Watz (johan.watz@kau.se)

Function, Diversity, and Ecological Complexity in Impacted Forested Riparian Systems

This project investigates how forestry practices and riparian disturbance affect the ecological functions of riparian predators and food-web structure in Swedish riparian ecosystems. Specifically, it examines how riparian disturbance:

• affects the functional diversity of riparian predators and their potential prey,
• influences the trophic positions of riparian spiders and brown trout, and the transfer of energy across the riparian interface,
• alters predation, prey selection and prey diversity.

The project combines environmental DNA, stable isotope analyses and advanced ecological data analysis. The results will improve our understanding of the ecological roles of key riparian predators and assess whether forest buffer strips in Swedish production forests are sufficient to maintain complex ecological functions.

Project period: 2019–2022
Funding: Formas and NRRV
Contacts: Jeff Marker and Denis Lafage

Habitat Compensation in Nature-Like Fishways

Many Swedish rivers have been heavily modified by hydropower development, restricting the movement of aquatic organisms between rivers, lakes and the sea. Nature-like fishways are designed to mimic natural streams and enable most fish species to bypass migration barriers.

Project period: 2010–2016
Contact: Stina Gustafsson