Abstract
Abstract. Climate changes affect aquatic ecosystems by altering temperatures and precipitation patterns, and the rear edges of the distributions of cold-water species are especially sensitive to these effects. The main goal of this study was to predict in detail how changes in air temperature and precipitation will affect streamflow, the thermal habitat of a cold-water fish (the brown trout, Salmo trutta), and the synergistic relationships among these variables at the rear edge of the natural distribution of brown trout. Thirty-one sites in 14 mountain rivers and streams were studied in central Spain. Models of streamflow were built for several of these sites using M5 model trees, and a non-linear regression method was used to estimate stream temperatures. Nine global climate models simulations for Representative Concentration Pathways RCP4.5 and RCP8.5 scenarios were downscaled to the local level. Significant reductions in streamflow were predicted to occur in all of the basins (max. −49 %) by the year 2099, and seasonal differences were noted between the basins. The stream temperature models showed relationships between the model parameters, geology and hydrologic responses. Temperature was sensitive to streamflow in one set of streams, and summer reductions in streamflow contributed to additional stream temperature increases (max. 3.6 °C), although the sites that are most dependent on deep aquifers will likely resist warming to a greater degree. The predicted increases in water temperatures were as high as 4.0 °C. Temperature and streamflow changes will cause a shift in the rear edge of the distribution of this species. However, geology will affect the extent of this shift. Approaches like the one used herein have proven to be useful in planning the prevention and mitigation of the negative effects of climate change by differentiating areas based on the risk level and viability of fish populations.
Highlights
IntroductionMagnuson and Destasio, 1997; Angilletta, 2009) and a key factor in energy balance of fish
Stream temperature is strongly correlated with air temperature (Mohseni and Stefan, 1999), whereas streamflow has a complex relationship with precipitation (McCuen, 1998; Gordon et al, 2004)
In accordance with the results presented the predicted synergy of streamflow reductions and water temperature increases will cause substantial losses of suitable fish habitat, especially for cold-water fish such as brown trout (Muñoz-Mas et al, 2016)
Summary
Magnuson and Destasio, 1997; Angilletta, 2009) and a key factor in energy balance of fish. It affects the rate of food intake, metabolic rate and growth performance (Forseth et al, 2009; Elliott and Elliott, 2010; Elliott and Allonby, 2013). Geology affects surface water temperatures by means of groundwater discharge (Caissie, 2006; Loinaz et al, 2013), influenced by the aquifer depth (shallow or deep) and the water’s residence time (Kurylyk et al, 2013; Snyder et al, 2015).
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