Effects of environmental fluctuations on fish metabolism: Atlantic salmon Salmo salar as a case study

Abstract

Using Atlantic salmon Salmo salar parr as study species, recent findings are summarized on how (1) diurnal variations in water temperature affects standard metabolic rate, (2) shelter may reduce routine metabolic rate and (3) fluctuations of water speed affect the costs of activity. The results suggest that the accuracy of bioenergetics models can be hampered if the effects of environmental fluctuations are omitted. Incorporating environmental fluctuations into estimates and models of fish metabolism will not only improve the accuracy of energy budget calculations, but also have crucial management implications for conservation and improve the capacity to predict effects of climate change.

Effect of short-term regulated temperature variations on the swimming economy of Atlantic salmon smolts

“…Many studies describe water temperature as the master variable controlling fishes’ swimming metabolism and energetic costs (Brett, 1965; Beauregard et al ., 2013; Enders and Boisclair, 2016). General assumptions state that, when fish are exposed to temperature changes during a sufficiently long period, they can obtain optimal performance by altering either their behaviour (preference/avoidance) or their physiology (adaptation/acclimation) (Bernatchez and Dodson, 1985; Lee et al ., 2003; Oligny-Hébert et al ., 2015).…”

“…This method was consistently used in recent years to successfully assess the effect of natural long-term or circadian temperature fluctuations in the swimming performance and metabolism of distinct fish species (Beauregard et al ., 2013; Chabot et al ., 2016; Enders and Boisclair, 2016), but, to our knowledge, none addressed the effects of sudden and more accentuated temperature fluctuations usually associated to hydropeaking operations. This type of information assessed at a small physiological scale is almost always left out of hydropeaking-related studies which are normally more ecologically oriented, but can represent the basal explanation for some of the described responses at the assemblage level.…”

Under what circumstances does the capture and tagging of wild Atlantic salmon Salmo salar smolts affect probability of return as adults?

“…Mild winters will modify parr metabolic rate (Fry, ; Enders & Boisclair, ), growth (Elliott & Hurley, ), and the physiological and morphological changes associated with smoltification (McCormick et al . , ), which could affect migration timing and smolt length or condition.…”

Exposure to exogenous egg cortisol does not rescue juvenile Chinook salmon body size, condition, or survival from the effects of elevated water temperatures

“…Notably, increasing temperatures alone are expected to greatly impact ectothermic organisms such as invertebrates and fishes, and oftentimes are considered to be negative (Ficke, Myrick, & Hansen, ; Stoks, Geerts, & De Meester, ). Indeed, warming waters generate offspring phenotypic traits such as smaller body size (Kuehne, Olden, & Duda, ; Whitney, Hinch, Patterson, & a., ), faster growth (Beacham & Murray, ), and increased metabolism (Enders & Boisclair, ). In turn, offspring performance and life history traits can also be affected, including lower thermal tolerance (Chen et al, ), earlier development (Fuhrman, Larsen, Steel, Young, & Beckman, ), altered migration timing (Crozier, ), and modified reproduction (Pankhurst & Munday, ), ultimately resulting in changes to fitness (e.g., survival; Martins et al, ; Whitney, Hinch, & Patterson, ).…”

“…Notably, increasing temperatures alone are expected to greatly impact ectothermic organisms such as invertebrates and fishes, and oftentimes are considered to be negative (Ficke, Myrick, & Hansen, 2007;Stoks, Geerts, & De Meester, 2014). Indeed, warming waters generate offspring phenotypic traits such as smaller body size (Kuehne, Olden, & Duda, 2012;Whitney, Hinch, Patterson, & a., 2014), faster growth (Beacham & Murray, 1990), and increased metabolism (Enders & Boisclair, 2016).…”