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

Abstract

Climate change affects aquatic ecosystems altering temperature and precipitation patterns, and the rear edge of the distribution of cold-water species is especially sensitive to them. The main goal was to predict in detail how change in air temperature and precipitation will affect streamflow, the thermal habitat of a cold-water fish (brown trout, Salmo trutta Linnaeus 1758), and their synergistic relationships at the rear edge of its natural distribution. 31 sites in 14 mountain rivers 15 and streams were studied in Central Spain. Models at several sites were built using regression trees for streamflow, and a non-linear regression method for stream temperature. Nine global climate models simulations for the RCP4.5 and RCP8.5 (Representative Concentration Pathways) scenarios were downscaled to a local level. Significant streamflow reductions were predicted in all basins (max. -49 %) by the year 2099, showing seasonal differences between them. The stream temperature models showed relationships between models parameters, geology and hydrologic responses. Temperature was sensitive to 20 the streamflow in one set of streams, and summer reductions contributed to additional stream temperature increases (max.3.6ºC), although the most deep-aquifer dependent sites better resisted warming. The predicted increase in water temperature reached up to 4.0ºC. Temperature and streamflow changes will cause a shift of the rear edge of the species distribution.However, geology conditioned the extent of this shift. Approaches like these should be useful in planning the prevention and mitigation of negative effects of climate change by differentiating areas based on the risk level and viability of fish 25 populations.

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.…”

Extreme heat events and the vulnerability of endemic montane fishes to climate change

“…A key step in estimating the frequency and magnitude of T extreme events in streams is accurately characterizing air-water temperature relationships, which involve a multitude of heat transfer pathways that change along environmental gradients and will differ between historical and future climates (Luce et al 2014). Another consideration is that our projections of T extreme events do not explicitly incorporate the role of streamflow in mediating air-water temperature relationships which, in addition to temperature, is forecasted to change in southern Appalachia (Anandhi and Bentley 2018) and elsewhere in the world (Santiago et al 2017). Increasing daily temperature variation is also likely to increase in the future (Wang and Dillon 2014).…”

Stream channel restoration increases climate resiliency in a thermally vulnerable Appalachian river

“…network topology; Ebersole et al ), and regional‐scale (e.g. precipitation; Merriam et al ; Santiago et al ) factors controlling thermal vulnerability to climate change. There is also a growing body of literature suggesting strategic conservation and restoration efforts, such as riparian restoration and structural enhancement or alteration (Hester et al ; Sawyer et al ; Justice et al ), can improve thermal suitability of degraded larger‐river systems.…”