Waning habitats due to climate change: the effects of changes in streamflow and temperature at the rear edge of the distribution of a cold-water fish

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.

Effects of climate change on the life stages of stream‐dwelling brown trout (Salmo trutta Linnaeus, 1758) at the rear edge of their native distribution range

“…Historical simulations were performed for procedure quality control (by comparing modelled versus observed data). The daily results of this local scale modelling are presented in Santiago, Muñoz‐Mas, et al (2017).…”

“…The literature on trout physical habitat structure is extensive (Armstrong, Kemp, Kennedy, Ladle, & Milner, 2003); however, only recently have the joint effects of flow and temperature been addressed to assess the persistence probability of affected trout populations (e.g., Muñoz‐Mas et al, 2016, 2018; Wenger et al, 2011). Santiago, Muñoz‐Mas, et al (2017) also showed that the synergistic effects of both thermal and hydrological changes (namely, stream temperature increase and streamflow reduction) will exacerbate suitable habitat loss for cold‐water species such as brown trout because streamflow reductions may increase stream thermal sensitivity.…”

“…High‐resolution spatial–temporal simulations (altitude metre to metre and time day to day) of thermal and hydraulic habitats were conducted. Daily stream temperature and modelled streamflow data (Santiago, Muñoz‐Mas, et al, 2017) from ad hoc downscaled Intergovernmental Panel on Climate Change (IPCC; representative concentration pathway [RCP] 4.5 and RCP 8.5) predictions were used as the input variables. Hydraulic habitat changes were simulated from previously predicted streamflow data using hydraulic simulation tools (River2D).…”

Climate change and European rivers: An eco‐hydromorphological perspective

“…This impact may be expressed differently among rivers, even in the same geographic area. Investigations in central Spain (Santiago et al, ) examining the viability of brown trout ( Salmo trutta L.) habitat in response to climate change illustrate how this response can vary among catchments depending on physical attributes. Projected reductions in streamflow (max.…”

Climate Associations with Headwater Streamflow in Managed Forests over 16 Years and Projections of Future Dry Headwater Stream Channels

“…In the Pacific Northwest, in particular, assessments of climate variability and projections of climate change in forested headwaters are important owing to the dominance of these drainages in the landscape, and their importance to multiple downstream and upland ecosystem services-yet we are just beginning to understand climate influences on forested headwater streams. Stream-temperature and streamflow changes are attributes often considered in watershed studies of climate change, as these factors affect stream ecological conditions and functions, especially species habitat suitability via myriad ecophysiological constraints [38,39,43]. In the Northwestern US more generally, at larger scales (i.e., larger landscapes and watersheds), climate projections include warmer temperatures [44][45][46][47] and altered precipitation patterns such as reduced snowpack-especially at low-to-mid elevations [48,49], which have many headwater basins in the region.…”