Behavioural thermoregulation in cold‐water freshwater fish: Innate resilience to climate warming?

Abstract

Temperature is a principal abiotic factor influencing the physiology and ecology of ectothermic organisms (Cossins & Bowler, 1987;Huey & Kingsolver, 1993). During periods of temperature change, ectotherms respond physiologically, including metabolic responses that maintain the functioning of key biological processes (Willmer et al., 2009). Many ectotherms also adapt their behaviour to better tolerate their thermal environment, where their ambient temperature determines whether a particular behaviour is expressed or which of a possible suite of behaviours is performed as the temperature changes (Abram et al., 2017). These behavioural changes represent an integrated, whole-body response to temperature change requiring the coordination of multiple physiological responses (e.g. metabolic rate, digestive processes and immunity) (Dell et al., 2011).The whole-body responses of ectotherms to temperature changes include behavioural thermoregulation, where the suboptimal temperature experienced by the individual results in a behavioural response to move to a different, more optimal temperature, so altering their physiological functioning (Abram et al., 2017;

Closing the gap between science and management of cold‐water refuges in rivers and streams

“…Thermal requirements of coldwater fishes and their responses to temperature heterogeneity have been reviewed extensively (Amat‐Trigo et al, 2023; Kefford et al, 2022; Morash et al, 2021; Richter & Kolmes, 2005). Here, we focus on recent advances in thermal biology relating to stress, heat tolerance, and CWR use.…”

“…To cope with thermal stress, juvenile and adult coldwater fishes may either resist warm conditions by moving long distances to tributaries or short distances to behaviorally thermoregulate in CWRs, or they may remain in river mainstems and tolerate warm conditions (Barrett & Armstrong, 2022). Thermoregulation involves moving between ambient water temperature and CWRs to maintain narrow temperature ranges consistent with physiologically optimal temperatures (Amat‐Trigo et al, 2023; Brewitt & Danner, 2014; Frechette et al, 2018; Gutowsky et al, 2017). Cold‐water refuges thus support species' persistence by enabling individuals to exploit fine‐scale thermal heterogeneity in systems where ambient thermal conditions would be lethal (Armstrong et al, 2021; Brewitt & Danner, 2014; Corey et al, 2017).…”

“…Homogeneous thermal conditions also make coldwater organisms vulnerable to losing access to cool water to avoid thermal stress and to warm water to optimize growth. Thus, homogenous water temperatures may inhibit adaptations that can have a negative population‐level response such as a decrease in survival and productivity that, in turn, decreases coldwater organisms' resilience (Amat‐Trigo et al, 2023; Armstrong et al, 2013, 2021; Pinsky et al, 2019; Whitney et al, 2016). To overcome higher temperatures, organisms may move to cold areas during periods of thermal stress (Armstrong & Schindler, 2013; Brewitt et al, 2017; Hahlbeck et al, 2022; Wilbur et al, 2020).…”

The effect of temperature on the dynamics of common bream Abramis brama migrations between the reservoir and its tributary

“…As reservoirs apparently disrupt and change the temperature gradient of riverine environments, the impact of a newly created temperature gradient (the reservoir–tributary gradient) on the biology of both native and nonnative fish species spreading from reservoirs is poorly understood and should be investigated in more detail (Šmejkal et al, 2023). In conclusion, the importance of understanding the preferred temperatures and related behavioural aspects and spatial distribution of fish is magnified in the context of the current process of global warming (Amat‐Trigo et al, 2023).…”

Disentangling effects of habitat on salmonid abundance in thermal refuges while accounting for imperfect detection

“…Some species populations can shift to segments throughout riverscapes, or the spatiotemporally heterogeneous ensemble of temperatures, flows, and cover types unfolding through time (Torgersen et al, 2022), buffered from the climate and weather (i.e., climate refugia; Isaak et al, 2016). Others must rely on localized thermal refuges, or cold‐water patches that fish inhabit for temporary thermal relief, for short‐term buffering against weather extremes (Amat‐Trigo et al, 2023; Brewitt et al, 2017; Kurylyk et al, 2015; Sullivan et al, 2021; Torgersen et al, 2012; Wilbur et al, 2020). Thermal refuges are critical for the short‐term survival of many individuals of a population, which can scale up to influence a species' adaptive capacity and resistance of a cold‐water‐dependent fish community to extreme weather (e.g., Beever et al, 2017; Lynch et al, 2014; Railsback & Harvey, 2023; Thorpe, 1994).…”