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Dams threaten salmonids by triggering temperature-dependent proliferative kidney disease

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Abstract

Dams provide different services for human society, but they also significantly disrupt ecosystems by altering natural flow and temperature regimes. Here, we describe a novel, unappreciated threat posed by reservoirs to one of the world’s most popular game fish, brown trout (Salmo trutta). We show that small river impoundments elevate downstream water temperature during summer, which increases the prevalence and abundance of Tetracapsuloides bryosalmonae parasite triggering proliferative kidney disease (PKD), an emerging disorder in salmonids across North America and Europe. Our study highlights the role of reservoirs in creating parasite and disease hotspots, while providing limited evidence that dams act as barriers to parasite spread. This makes downstream areas from reservoirs valuable sentinel sites for monitoring climate impacts on riverine ecosystems. Ultimately, the assessment of dams requires a more holistic approach, where the disease risks are included in the decision-making process balancing human needs with the health of aquatic ecosystems.

Data availability

All data and code supporting the findings of this study are available in the Figshare repository under the https://doi.org/10.6084/m9.figshare.28595468.v4. Source data for all figures and analyses can be accessed directly through this repository. Any additional information is available from the corresponding author upon reasonable request.

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Acknowledgements

We thank Alfonso Diaz Suarez, Gustav Lauringson, Karl-Erik Aavik, Tanel Ader, Herki Tuus and Veljo Kisand for their assistance and support, Põlula Fish Rearing Centre of State Forest Management Centre (RMK) for logistical support and Oksana Burimski for laboratory assistance. Vihula III dam and reservoir photo (10.6 ha) at the Mustoja river, shown in Fig. 1G, is based on a drone photo from 10.07.2023, kindly provided by Gunnar Laak. The study was funded by Estonian Ministry of Regional Affairs and Agriculture, contract no. 4-1/22/6, Estonian Research Council, grant no. PSG849, PRG852, PRG3078 and Swedish research council for sustainable development FORMAS, grant no. 2021-01643.

Funding

Open access funding provided by Swedish University of Agricultural Sciences.

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Authors and Affiliations

  1. Chair of Aquaculture, Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences, Tartu, Estonia

    Magnus Lauringson, Lilian Pukk, Siim Kahar, Riho Gross & Anti Vasemägi

  2. Department of Aquatic Resources, Institute of Freshwater Research, Swedish University of Agricultural Sciences, Drottningholm, Sweden

    Joacim Näslund & Anti Vasemägi

Authors

  1. Magnus Lauringson
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  2. Joacim Näslund
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  3. Lilian Pukk
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  4. Siim Kahar
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  5. Riho Gross
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  6. Anti Vasemägi
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Contributions

A.V. and M.L. contributed equally to this work. A.V. and M.L. conceived the study. Methodology was developed by A.V., J.N., L.P., M.L. Investigation was carried out by A.V., L.P., M.L., R.G. and S.K. Visualization was performed by A.V., J.N. and M.L. The original draft was written by A.V., J.N. and M.L., and all authors contributed to review and editing.

Corresponding author

Correspondence to
Anti Vasemägi.

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Lauringson, M., Näslund, J., Pukk, L. et al. Dams threaten salmonids by triggering temperature-dependent proliferative kidney disease.
Commun Biol (2026). https://doi.org/10.1038/s42003-025-09470-1

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