title: Climate-induced warming imposes a threat to north European spring ecosystems.
abstract: Interest in climate change effects on groundwater has increased dramatically during the last decade. The mechanisms of climate-related groundwater depletion have been thoroughly reviewed, but the influence of global warming on groundwater-dependent ecosystems (GDEs) remains poorly known. Here we report long-term water temperature trends in 66 northern European cold-water springs. A vast majority of the springs (82%) exhibited a significant increase in water temperature during 1968-2012. Mean spring water temperatures were closely related to regional air temperature and global radiative forcing of the corresponding year. Based on three alternative climate scenarios representing low (RCP2.6), intermediate (RCP6) and high-emission scenarios (RCP8.5), we estimate that increase in mean spring water temperature in the region is likely to range from 0.67 °C (RCP2.6) to 5.94 °C (RCP8.5) by 2086. According to the worst-case scenario, water temperature of these originally cold-water ecosystems (regional mean in the late 1970s: 4.7 °C) may exceed 12 °C by the end of this century. We used bryophyte and macroinvertebrate species data from Finnish springs and spring-fed streams to assess ecological impacts of the predicted warming. An increase in spring water temperature by several degrees will likely have substantial biodiversity impacts, causing regional extinction of native, cold-stenothermal spring specialists, whereas species diversity of headwater generalists is likely to increase. Even a slight (by 1 °C) increase in water temperature may eliminate endemic spring species, thus altering bryophyte and macroinvertebrate assemblages of spring-fed streams. Climate change-induced warming of northern regions may thus alter species composition of the spring biota and cause regional homogenization of biodiversity in headwater ecosystems.
authors: Department of Ecology, University of Oulu, P.O. Box 3000, FI-90014, Oulu, Finland.
authors: Jussi
authors: J
authors: Jyväsjärvi
authors: Water Resources and Environmental Engineering Research Group, University of Oulu, P.O. Box 3000, FI-90014, Oulu, Finland.
authors: Hannu
authors: H
authors: Marttila
authors: Water Resources and Environmental Engineering Research Group, University of Oulu, P.O. Box 3000, FI-90014, Oulu, Finland.
authors: Pekka M
authors: PM
authors: Rossi
authors: Water Resources and Environmental Engineering Research Group, University of Oulu, P.O. Box 3000, FI-90014, Oulu, Finland.
authors: Pertti
authors: P
authors: Ala-Aho
authors: Division of Land and Water Resources Engineering, KTH Royal Institute of Technology, SE-100 44, Stockholm, Sweden.
authors: Bo
authors: B
authors: Olofsson
authors: Geological Survey of Sweden, P.O. Box 670, 75128, Uppsala, Sweden.
authors: Jakob
authors: J
authors: Nisell
authors: Geological Survey of Finland, P.O. Box 96, FI-02151, Espoo, Finland.
authors: Birgitta
authors: B
authors: Backman
authors: Metsähallitus, P.O. Box 94, FI-01301, Vantaa, Finland.
authors: Jari
authors: J
authors: Ilmonen
authors: Department of Ecology, University of Oulu, P.O. Box 3000, FI-90014, Oulu, Finland.
authors: Risto
authors: R
authors: Virtanen
authors: Ruuhikoskenkatu 17 B 5, Salo, Finland.
authors: Lauri
authors: L
authors: Paasivirta
authors: Finnish Environment Institute, Freshwater Centre, Groundwater and Water Supply, Mechelininkatu 34a, FI-00260, Helsinki, Finland.
authors: Ritva
authors: R
authors: Britschgi
authors: Water Resources and Environmental Engineering Research Group, University of Oulu, P.O. Box 3000, FI-90014, Oulu, Finland.
authors: Bjørn
authors: B
authors: Kløve
authors: Department of Ecology, University of Oulu, P.O. Box 3000, FI-90014, Oulu, Finland.|Finnish Environment Institute, Natural Environment Centre, FI-90014, Oulu, Finland.
authors: Timo
authors: T
authors: Muotka
mesh_terms: D063147:Animal Distribution; D000818:Animals; D044822:Biodiversity; D044002:Bryophyta / Q000502:physiology*; D005387:Finland; D057232:Global Warming; D007448:Invertebrates / Q000502:physiology*; D008954:Models, Biological; D060985:Natural Springs; D063148:Plant Dispersal; D012621:Seasons; D013548:Sweden; D013696:Temperature
keywords: aquifer; bryophytes; climate change; endemic; groundwater-dependent ecosystems; invertebrates; time-series