Climate models predict changes to flows and biota of northern rivers

Press release 2018-03-20 at 9:34

Finnish Environment Institute and University of Oulu press release 

Jäätynyt vesi
Water flows of the late autumn and spring will change in the future. © Kaisa-Riikka Mustonen, University of Oulu

The habitats of species in Finland's rivers will move northward as climate change causes temperatures to rise. In addition, seasonal fluctuation in the flow of rivers will become more irregular than it is now. Small headwater streams will experience greater changes in species than larger rivers, according to a study by the Finnish Environment Institute and the University of Oulu.

According to climate scenarios, the rise in air temperatures at the end of the century will be the greatest in the northern areas of Finland. The expected composition of fauna living on the bottoms of rivers reflects changes in temperature.

"According to the forecast, the range of various species will be spreading northward, and as a result of this, the diversity of species in northern rivers would increase. On the other hand, some northern species may disappear from their present habitats in the future", says Dr. Kaisa-Riikka Mustonen, postdoctoral researcher at the Department of Ecology and Genetics at the University of Oulu.

Greatest changes in small headwater streams

Clear changes were noticed in the forecast on river flows and the seasonal variation became more difficult to anticipate. The greatest change in the array of species would occur in waterways in which the flow changes the most. Small headwater streams are especially susceptible to changes in water flows and consequently also to changes in species living in them.

"It is clear that climate change will alter aquatic nature. Changes in temperature and in the amount of precipitation will affect many functions of the catchment areas of the rivers. In addition, the effects of land use and other human activities will combine with those of climate change. In the study of the impact of climate change on waterways, we need to more widely take into account various factors and their combined impact", says Heikki Mykrä, special researcher at the Finnish Environment Institute.

Climate change poses challenges for the protection and management of waters. Shade needs to be maintained especially in small bodies of water to keep the rise in water temperature as low as possible.

Researchers at the Finnish Environment Institute and the University of Oulu investigated how changes in air temperature and hydrology affect the composition of the bottom fauna in the rivers. In the study scenarios produced by climate models on river flow simulations were combined with models that predict the distribution of species. The research was published in the Global Change Biology publication series.

World Water Day is on 22 March, 2018. This year's theme, "Nature for Water", draws attention to how the quality of water can be improved through nature-based solutions. The purpose of the UN-declared World Water Day is to increase information on the impact of water reserves on economic productivity and social well-being.

"With World Water day coming up it is good to keep in mind how important it is to study the interaction between climate and aquatic nature", says Heikki Mykrä.

Further information

Special researcher Heikki Mykrä, Finnish Environment Institute
tel. +358 295251436,

Postdoctoral researcher Kaisa-Riikka Mustonen, Department of Ecology and Genetics at the University of Oulu.
tel. +358 4057 89989,



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