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Influence of seasonal temperature on the repeat swimming performance of rainbow trout Oncorhynchus mykiss
Abstract
While the temperature dependence of exercise performance in fishes is reasonably well documented, information on the temperature dependence of metabolic recovery and reperformance is scant. This study examined the recovery of swimming performance after exhaustive exercise in rainbow trout Oncorhynchus mykiss at seasonal temperatures ranging from 5 to 17 degrees C and explored the relationship between performance and preceding metabolic state. The primary objective of the study was to test the hypothesis that increased temperature increases the capability of rainbow trout to repeat a critical swimming speed (U(crit)), as assessed by two consecutive critical swimming speed tests separated by a 40 min rest interval. An additional expectation was that certain plasma ionic, metabolic and humoral parameters would be correlated with how well fish reperformed and so plasma levels of lactate, potassium, ammonia, osmolality, sodium and cortisol, as well as hematocrit, were monitored before, during and after the swim challenges via an indwelling cannula in the dorsal aorta. As expected, performance in the first U(crit) test (U(crit1)) was positively related to temperature. However, the relationship between U(crit1) and reperformance (U(crit2)) was not dependent on acclimation temperature in a simple manner. Contrary to our expectations, U(crit2) was less than U(crit1) for warm-acclimated fish (14.9+/-1.0 degrees C), whereas U(crit2) equaled U(crit1) for cold-acclimated fish (8.4+/-0.9 degrees C). Cold-acclimated fish also exhibited a lower U(crit1) and less metabolic disruption compared with warm-acclimated fish. Thus, while warm acclimation conferred a faster U(crit1), a similar swimming speed could not be attained on subsequent swim after a 40 min recovery period. This finding does not support the hypothesis that the ability of rainbow trout to reperform on U(crit) test is improved with temperature. Both plasma lactate and plasma potassium levels were strongly correlated with U(crit1) performance. Therefore, the higher U(crit1) of warm-acclimated fish may have been due in part to a greater anaerobic swimming effort compared with cold-acclimated fish. In fact, a significant correlation existed between the plasma lactate concentration prior to the start of the second test and the subsequent U(crit2) performance, such that U(crit2) decreased when a threshold plasma lactate level of around 12.2 mmol l(-1) was surpassed for the initial swim. No other measured plasma variable showed a significant relationship with the U(crit2) performance. We conclude that warm-acclimated fish, by apparently swimming harder and possibly more anaerobically compared with cold-acclimated fish, were unable to recovery sufficiently well during the fixed recovery period to repeat this initial level of performance, and this poorer repeat performance was correlated with elevations in plasma lactate levels.
... As salmonids' AAS is reduced due to increasing river temperatures, they may not be able to maintain the work needed to migrate upstream and complete spawning. In addition to aerobic swimming, migrating adult salmon must also use anaerobic burst swimming to negotiate hydraulic challenges, avoid predation, dig redds (nests), spawn and defend territories (Rand and Hinch, 1998;Healey et al., 2003;Jain and Farrell, 2003;Berejikian et al., 2007). Salmon can sustain aerobic swimming for extended periods, supporting migrations of hundreds of kilometers; however, they can only maintain anaerobic exercise for shorter durations. ...
... Salmon can sustain aerobic swimming for extended periods, supporting migrations of hundreds of kilometers; however, they can only maintain anaerobic exercise for shorter durations. They must then restore homeostasis and metabolically recover by clearing lactate and restoring glycogen, high-energy phosphates, oxygen stores and osmoregulatory balance (Wood, 1991;Milligan, 1996;Kieffer, 2000;Jain and Farrell, 2003;Lee et al., 2003a;Suski et al., 2007;Raby et al., 2015), a measurement termed "excess post exercise oxygen consumption" (EPOC) (Gaesser and Brooks, 1984). To complete upstream migration, salmon need to minimize both the duration and energetic costs of recovery (Claireaux et al., 2000;Suski et al., 2007;Eliason and Farrell, 2016). ...
... To complete upstream migration, salmon need to minimize both the duration and energetic costs of recovery (Claireaux et al., 2000;Suski et al., 2007;Eliason and Farrell, 2016). However, warming river temperatures may prolong recovery time (Prystay et al., 2017;Kraskura et al., 2021), which has clear fitness costs and could result in migration failure in Pacific salmon (Jain and Farrell, 2003;Lee et al., 2003a;Eliason et al., 2011;Burnett et al., 2014b;Raby et al., 2015). ...
Climate change is causing large declines in many Pacific salmon populations. In particular, warm rivers are associated with high levels of premature mortality in migrating adults. The Fraser River watershed in British Columbia, Canada, supports some of the largest Chinook salmon (Oncorhynchus tshawytscha) runs in the world. However, the Fraser River is warming at a rate that threatens these populations at critical freshwater life stages. A growing body of literature suggests salmonids are locally adapted to their thermal migratory experience, and thus, population-specific thermal performance information can aid in management decisions. We compared the thermal performance of pre-spawning adult Chinook salmon from two populations, a coastal fall-run from the Chilliwack River (125 km cooler migration) and an interior summer-run from the Shuswap River (565 km warmer migration). We acutely exposed fish to temperatures reflecting current (12°C, 18°C) and future projected temperatures (21°C, 24°C) in the Fraser River and assessed survival, aerobic capacity (resting and maximum metabolic rates, absolute aerobic scope (AAS), muscle and ventricle citrate synthase), anaerobic capacity (muscle and ventricle lactate dehydrogenase) and recovery capacity (post-exercise metabolism, blood physiology, tissue lactate). Chilliwack Chinook salmon performed worse at high temperatures, indicated by elevated mortality, reduced breadth in AAS, enhanced plasma lactate and potassium levels and elevated tissue lactate concentrations compared with Shuswap Chinook salmon. At water temperatures exceeding the upper pejus temperatures (Tpejus, defined here as 80% of maximum AAS) of Chilliwack (18.7°C) and Shuswap (20.2°C) Chinook salmon populations, physiological performance will decline and affect migration and survival to spawn. Our results reveal population differences in pre-spawning Chinook salmon performance across scales of biological organization at ecologically relevant temperatures. Given the rapid warming of rivers, we show that it is critical to consider the intra-specific variation in thermal physiology to assist in the conservation and management of Pacific salmon.
... re-gaining cardiorespiratory, hormone and metabolite balance; Wood, 1991;Scarabello et al., 1992;Wang et al., 1994;Cech et al., 2004;Zhang et al., 2018). Pacific salmon have an extraordinary ability to repeat their swim performance after only 40-45 min of rest and despite the fact that metabolic rate has not fully recovered to routine levels Jain et al., 1998;Jain and Farrell, 2003;MacNutt et al., 2006;Wagner et al., 2006;Eliason et al., 2013b). However, impaired recovery at high temperatures may mean consecutive swimming challenges are more taxing for female salmon, thereby increasing their physiological burden or delaying migration compared to males. ...
... Pacific salmon are well known to be able to repeat maximum swim performance after only a short recovery duration (e.g. 30-60 min)-well before they have fully recovered back to baseline metabolism Jain et al., 1998;Jain and Farrell, 2003;MacNutt et al., 2006;Wagner et al., 2006;Eliason et al., 2013b). These studies suggest that salmon recover to 30-70% of MMR and are then able to repeat their swim performance. ...
... Indeed, salmon have an outstanding capacity to repeat maximum swimming performance given only ∼45 min to recover between tests and before they have physiologically recovered back to baseline levels (Eliason et al., 2013b). Between tests, reported MO 2 values in salmon decreased an average of 30%-70% of their reported MMR, with most values being close to 50% of MMR Jain et al., 1998;Jain and Farrell, 2003;MacNutt et al., 2006;Wagner et al., 2006;Eliason et al., 2013b). The recovery of metabolism from MMR to 50% of MMR value is suggested to coincide with the 'rapid' phase of physiological recovery (Zhang et al., 2018) when muscle high energy phosphate levels are restored (Scarabello et al., 1991;Eliason et al., 2020), oxygen stores are replenished (McKenzie, 2004), catecholamines levels decrease (Nikinmaa and Tufts, 1989;Tufts and Randall, 1989) and cardiac output declines (Eliason et al., 2013a). ...
Adult female Pacific salmon can have higher migration mortality rates than males, particularly at warm temperatures. However, the mechanisms underlying this phenomenon remain a mystery. Given the importance of swimming energetics on fitness, we measured critical swim speed, swimming metabolism, cost of transport, aerobic scope (absolute and factorial) and exercise recovery in adult female and male coho salmon (Oncorhynchus kisutch) held for 2 days at 3 environmentally relevant temperatures (9°C, 14°C, 18°C) in fresh water. Critical swimming performance (Ucrit) was equivalent between sexes and maximal at 14°C. Absolute aerobic scope was sex- and temperature-independent, whereas factorial aerobic scope decreased with increasing temperature in both sexes. The full cost of recovery from exhaustive exercise (excess post-exercise oxygen consumption) was higher in males compared to females. Immediately following exhaustive exercise (i.e. 1 h), recovery was impaired at 18°C for both sexes. At an intermediate time scale (i.e. 5 h), recovery in males was compromised at 14°C and 18°C compared to females. Overall, swimming, aerobic metabolism, and recovery energetics do not appear to explain the phenomenon of increased mortality rates in female coho salmon. However, our results suggest that warming temperatures compromise recovery following exhaustive exercise in both male and female salmon, which may delay migration progression and could contribute to en route mortality.
... The majority of the studies conducted about this theme are focused on fish captured at the same time and later acclimated to different temperatures (e.g. Fuiman & Ottey, 1992;Myrick & Cech, 2000;Jain & Farrel, 2003), which only reflect the response of tested fish to the variation in temperature and do not consider potential site and season-specific influences to which fish are responding. ...
... Most of the existent literature focused on the relationship between water temperature and fish swimming performance reveal that fish tend to swim better at higher temperatures (e.g. Jain & Farrel, 2003;Allen et al., 2006;Ruiz-Legazpi et al., 2018) contradicting the results obtained in our study. However, some of these studies were conducted using fish captured in the same season ...
... of the year and later acclimated to different temperatures (Allen et al., 2006;Jain & Farrel, 2003). These studies failed to account for the whole intra-annual environmental variability that can be found in riverine systems. ...
Swimming performance is a determinant characteristic for the survival of fish species and is related to their response to environmental disturbance. In this study, we evaluated how seasonal environmental variability of Mediterranean intermittent rivers influences swimming performance of a resident Iberian fish, the ruivaco, Achondrostoma oligolepis. Approximately forty fish of A. oligolepis were captured in each annual season (i.e. winter, spring, summer and autumn), from a Portuguese intermittent river, and compared in terms of swimming behaviour and capacity (Ucrit test). We found a clear distinction in fish willingness to swim and swimming performance between seasons. Fish were more willing to swim during autumn and winter, as opposed to less energetic behaviour during spring and summer. Higher Ucrit values were observed during autumn (0.42 ± 0.17 m/s) and winter (0.48 ± 0.25 m/s), which in the studied river are typically characterised by high flows, strongly influenced by rainfall patterns. Results from this study contribute to increase the knowledge on movement dynamics of small, typically known as resident, fish species and how this relates to natural and seasonal environmental variability.
... As temperatures above T opt cause a decline in aerobic (and cardiac) scope, fish can either become less active to avoid becoming anaerobic, or recruit anaerobic metabolic pathways to meet their energetic demands when performing activities exceeding their aerobic capacity. It is well established that salmonids increase their reliance on anaerobic swimming as they approach U crit at supra-optimal temperatures (Brett 1964;Jain and Farrell 2003;Eliason et al. 2013a). For example, Eliason et al. (2013b) found that sockeye salmon exposed to high temperatures (22-26 °C) had elevated plasma lactate even at rest, and glucose depletion with swimming, providing evidence of compromised oxygen delivery to tissues and anaerobic metabolism. ...
... Is there a threshold for plasma lactate concentration indicative of mortality? A threshold of 10-13mmol L −1 has been suggested as the point after which swimming performance and recovery become impaired, and at which mortality is likely to occur (Stevens and Black 1966;Farrell et al. 1998;Jain and Farrell 2003;Crossin et al. 2009;Gale et al. 2014). At this point however, such physiological thresholds remain unknown and should be explored further. ...
... Habitat that surpass lactate levels of 10-13 mmol/L cannot repeat swim performance, and plasma lactate levels must return beneath these values before fish can resume swimming or migration Jain and Farrell, 2003;Stevens and Black, 1966). Lactate is one physiological response variable that shows consistent trends with survivorship and timely arrival to spawning grounds: salmon that survive en route to spawning grounds consistently had lower lactate levels than individuals that did not arrive or were delayed, and survivor levels were recorded below 10 mmol/L in 7 primary tagging or moribund studies (Fig. 4). ...
... Salmon are categorized as survivors if they passed upriver locations specific to the study or survived lab treatments and non-survivors if they did not reach or delayed arrival to these locations or were categorized as moribund in the laboratory setting. The horizontal dashed line at 10 mmol L À1 denotes the lactate threshold value required to repeat swim performance Jain and Farrell, 2003;Stevens and Black, 1966). stress indicator (Akbarzadeh et al., 2018), already having shown utility in measuring rapid immune response and screening for pathogens in Pacific salmon (Connon et al., 2018;Miller et al., 2014). ...
The cardiorespiratory system distributes oxygen and other factors (nutrients, wastes, hormones etc.) around the body and thus plays a central role in mediating many physiological processes such as digestion, locomotion, and reproduction. Building from a rich body of foundational research, cardiorespiratory physiology techniques are now being used for applied, conservation purposes. These techniques can evaluate performance at the whole animal, organ, or cellular levels. At the whole animal level, metabolism and energetic capacities are routinely measured. Aerobic scope (the maximum energetic capacity of a fish beyond maintenance; absolute aerobic scope = maximum metabolic rate − standard metabolic rate) is used to identify optimal conditions for fish. At the level of the heart, heart rate biologging and biotechnology techniques enable researchers to monitor performance in free-ranging fish, while Arrhenius breakpoint tests can measure the optimal and upper thermal limits for the heart. At the cellular level, blood sampling is an easy and effective way to gain a wealth of information about the physiological status of the fish. Several case studies are presented to illustrate how cardiorespiratory physiology techniques have been effectively put into practice (Pacific salmon conservation, shark fisheries-induced mortality, pelagic fishes responding to oil). We conclude with some recommendations to continue moving the field forward and advance fish conservation.
... Several studies have shown that the ratio of lactate produced:disposed increases at intermediateto-high speeds (Weber 1991;Peake and Farrell 2004;Svendsen et al. 2010). The increase of lactate in body fluids and tissues limits the swimming performance of fishes (Black et al. 1962;Jain et al. 1998;Kieffer 2000;Jain and Farrell 2003;Widmer et al. 2006). In addition, upper sustained speeds might be limited by the body posture and fin movements that are necessary to create thrust. ...
... Studies on the effect of temperature on metabolic rates have proliferated as temperature, considered the "abiotic master factor", has profound effects on fish physiology (Fry 1967;Angilletta 2009). In fact, nearly every physiological process is affected by temperature, and it is not surprising therefore, that fishes may use temperature as an ecological resource by exploiting thermal gradients to enhance physiological performance (Di Santo and Bennett 2011a;Krehl and Soetbeer 1899;Fry 1967;Magnuson et al. 1979;Wardle 1980;Jain and Farrell 2003;DiGirolamo et al. 2012). ...
Ecological physiologists and biomechanists have been broadly investigating swimming performance in a diversity of fishes, however the connection between form, function and energetics of locomotion has been rarely evaluated in the same system and under climate change scenarios. In this perspective I argue that working within the framework of 'EcoPhysioMechanics', i.e., integrating energetics and biomechanics tools, to measure locomotor performance and behavior under different abiotic factors, improves our understanding of the mechanisms, limits and costs of movement. To demonstrate how ecophysiomechanics can be applied to locomotor studies, I outline how linking biomechanics and physiology allows us to understand how fishes may modulate their movement to achieve high speeds or reduce the costs of locomotion. I also discuss how the framework is necessary to quantify swimming capacity under climate change scenarios. Finally, I discuss current dearth of integrative studies and gaps in empirical datasets that are necessary to understand fish swimming under changing environments.
... The mechanistic explanations for the lack of these effects at elevated temperatures have been attributed to aerobic metabolic capability (e.g., arterial oxygen delivery, a decrease in dissolved oxygen) and ion fluxes being compromised at elevated temperatures (Farrell et al., 1996;Gonzalez and McDonald, 1994;Pang et al., 2013). Jain and Farrell (2003) found that the repeat swimming performance of rainbow trout (Oncorhynchus mykiss) was compromised at warm, but not cold, temperatures, with warm-acclimated fish failing to attain a similar swimming speed on a second U CRIT swim after a 40 min recovery period. Plasma lactate concentrations were much greater in warm acclimated fish prior to the second U CRIT trial that surpassed a lactate threshold and hindered performance (Jain and Farrell, 2003). ...
... Jain and Farrell (2003) found that the repeat swimming performance of rainbow trout (Oncorhynchus mykiss) was compromised at warm, but not cold, temperatures, with warm-acclimated fish failing to attain a similar swimming speed on a second U CRIT swim after a 40 min recovery period. Plasma lactate concentrations were much greater in warm acclimated fish prior to the second U CRIT trial that surpassed a lactate threshold and hindered performance (Jain and Farrell, 2003). It is unlikely that lactate levels were driving the lack of an effect on upper thermal tolerance in our study, but the null effect may be linked to other variables equally affecting control and exercise-trained fish at elevated temperatures (e.g., decrease in dissolved oxygen, ion channel and neural imbalance, protein or enzyme limitation, effects on membrane fluidity; Clark et al., 2008;Farrell et al., 1996;Gonzalez and McDonald, 1994;Iftikar and Hickey, 2013;Overgaard et al., 2012). ...
The progression of climate warming will expose ectotherms to transient heatwave events and temperatures above their tolerance range at increased frequencies. It is therefore pivotal that we understand species' physiological limits and the capacity for various controls to plastically alter these thresholds. Exercise training could have beneficial impacts on organismal heat tolerance through improvements in cardio-respiratory capacity, but this remains unexplored. Using juvenile Chinook salmon (Oncorhynchus tshawytscha), we tested the hypothesis that exercise training improves heat tolerance through enhancements in oxygen-carrying capacity. Fish were trained once daily at 60% of their maximum sustainable swim speed, UCRIT, for 60 min. Tolerance to acute warming was assessed following three weeks of exercise training, measured as the critical thermal maximum (CTMAX). CTMAX measurements were coupled with examinations of the oxygen carrying capacity (haematocrit, haemoglobin concentration, relative ventricle size, and relative splenic mass) as critical components of the oxygen transport cascade in fish. Contrary to our hypothesis, we found that exercise training did not raise the CTMAX of juvenile Chinook salmon with a mean CTMAX increase of just 0.35 °C compared to unexercised control fish. Training also failed to improve the oxygen carrying capacity of fish. Exercise training remains a novel strategy against acute warming that requires substantial fine-tuning before it can be applied to the management of commercial and wild fishes.
... Furthermore, strenuous exercise is associated with K + leak from skeletal muscles (Gale et al., 2013;Danylchuk et al., 2014), which results in prolonged increases in [K + ] o as a result of the slow clearance of K + ions from the blood plasma of fish (Soivio and Oikari, 1976;Kieffer, 2000). As increases in temperature, heart rate and [K + ] o may have synergistic effects on EE (Dominguez and Fozzard, 1970;Kline and Morad, 1978;Gettes, 1992;Lindinger, 1995;Jain and Farrell, 2003;Badr et al., 2018), temperature challenges of ventricular myocytes were made in three different [K + ] o at each test temperature. Based on the recent findings on roach ventricular myocytes (Badr et al., 2018), EE was predicted to be depressed by high [K + ] o . ...
... In mammals and fish, the concentration of plasma [K + ] o increases in exercise as a consequence of K + efflux from the skeletal muscles (Prosser et al., 1970;Soivio and Oikari, 1976;Turner et al., 1983;Wells et al., 1986;Nielsen and Lykkeboe, 1992;Kieffer, 2000;Jain and Farrell, 2003;Danylchuk et al., 2014). Furthermore, exercise-and temperature-induced increase in heart rate may result in elevation of the paracellular K + concentration in the myocardium by similar mechanisms to those in skeletal muscles (Cohen et al., 1976;Kline and Morad, 1978). ...
Electrical excitability (EE) is vital for cardiac function and strongly modulated by temperature and external K+ concentration ([K+]o), as formulated in the hypothesis of temperature-dependent deterioration of electrical excitability (TDEE). As little is known about EE of arctic stenothermic fishes, we tested the TDEE hypothesis on ventricular myocytes of polar cod (Boreogadus saida) and navaga (Eleginus nawaga) of the Arctic Ocean and those of temperate freshwater burbot (Lota lota). Ventricular action potentials (APs) were elicited in current-clamp experiments at 3, 9 and 15°C, and AP characteristics and the current needed to elicit APs were examined. At 3°C, ventricular APs of polar cod and navaga were similar but differed from those of burbot in having a lower rate of AP upstroke and a higher rate of repolarization. EE of ventricular myocytes - defined as the ease with which all-or-none APs are triggered - was little affected by acute temperature changes between 3 and 15°C in any species. However, AP duration (APD50) was drastically reduced at higher temperatures. Elevation of [K+]o from 3 to 5.4 mmol l-1 and further to 8 mmol l-1 at 3, 9 and 15°C strongly affected EE and AP characteristics in polar cod and navaga, but had a lesser effect in burbot. In all species, ventricular excitation was resistant to acute temperature elevations, while small increases in [K+]o severely compromised EE, in particular in the marine stenotherms. This suggests that EE of the heart in these Gadiformes species is resistant against acute warming, but less so against the simultaneous temperature and exercise stresses.
... Most of what we know regarding the effects of temperature on metabolism, aerobic scope and fitness in fishes comes from laboratory-based studies conducted on animals acclimated to stable thermal profiles (e.g. Brett, 1971;Claireaux et al., 2000;Clark et al., 2011;Crespel et al., 2017;Healy and Schulte, 2012;Jain and Farrell, 2003;Mazloumi et al., 2017;Norin et al., 2014;Poletto et al., 2017;Reidy et al., 2000). These studies provide important mechanistic insighthowever, they do not readily allow extrapolation to natural conditions. ...
... It was found that bacterial oxygen consumption was negligible and was therefore not used to correct the data. Maximum Ṁ O2 was measured immediately after the critical swimming speed test (U crit ) (Jain and Farrell, 2003) when fish were fully exhausted. O 2 depletion was continuously monitored in 30 s increments immediately after the U crit test for 5 min, or until the rate of O 2 consumption began to slow down as the fish recovered. ...
Environmental variability in aquatic ecosystems makes the study of ectotherms complex and challenging. Physiologists have historically overcome this hurdle in the laboratory by using 'average' conditions, representative of the natural environment for any given animal. Temperature, in particular, has widespread impact on the physiology of animals, and it is becoming increasingly important to understand these effects as we face future climate challenges. The majority of research to date has focused on the expected global average increase in temperature; however, increases in climate variability are predicted to affect animals as much or more than climate warming. Physiological responses associated with the acclimation to a new stable temperature are distinct from those in thermally variable environments. Our goal is to highlight these physiological differences as they relate to both thermal acclimation and the 'fallacy of the average' or Jensen's inequality using theoretical models and novel empirical data. We encourage the use of more realistic thermal environments in experimental design to advance our understanding of these physiological responses such that we can better predict how aquatic animals will respond to future changes in our climate.
... Notably, the [K ϩ ] o remains elevated for several hours after exercise and handling stress (38,48). Furthermore, the exercise-related increase in [K ϩ ] o and mortality of the fish are dependent on temperature and thermal history of the animal (11,14,23): e.g., the exerciseinduced increase in [K ϩ ] o is much higher in warm-acclimated rainbow trout (Oncorhynchus mykiss) (18.9°C;~5 mM) than in cold-acclimated trout (4.9°C;~3 mM) (23). Indeed, the postexercise mortality in Atlantic salmon and coral grouper (Cephalopholis miniata) is more frequent at high than low temperatures (1,7,24). ...
... Notably, the [K ϩ ] o remains elevated for several hours after exercise and handling stress (38,48). Furthermore, the exercise-related increase in [K ϩ ] o and mortality of the fish are dependent on temperature and thermal history of the animal (11,14,23): e.g., the exerciseinduced increase in [K ϩ ] o is much higher in warm-acclimated rainbow trout (Oncorhynchus mykiss) (18.9°C;~5 mM) than in cold-acclimated trout (4.9°C;~3 mM) (23). Indeed, the postexercise mortality in Atlantic salmon and coral grouper (Cephalopholis miniata) is more frequent at high than low temperatures (1,7,24). ...
Exercise, capture and handling stress in fishes can elevate extracellular K+ concentration ([K+]o) with potential impact on heart function. Therefore, effects of [K+]o on excitability of ventricular myocytes of winter-acclimatized roach (Rutilus rutilus) (4{plus minus}0.5{degree sign}C) were examined at different temperatures and pacing rates. Frequencies corresponding to in vivo heart rates at 4{degree sign}C (0.37Hz), 14{degree sign}C (1.16Hz) and 24{degree sign}C (1.96Hz) had no effect on excitability of myocytes. Acute temperature increase from 4{degree sign}C to 14{degree sign}C did not affect excitability, but further rise to 24{degree sign}C markedly decreased it: stimulus current and critical depolarization were about 25% and 14% higher, respectively, at 24{degree sign}C than at 4{degree sign}C and 14{degree sign}C (P<0.05). This depression was probably due to temperature-related mismatch between inward Na+ and outward K+ currents. Contrary, increase of [K+]o from 3 to 5.4 mM and further to 8 mM at 24{degree sign}C reduced stimulus current needed to trigger AP. Other aspects of excitability were strongly depressed by high [K+]o: maximum rate of AP upstroke and AP duration were drastically (89% and 50%, respectively) reduced in 8 mM [K+]o. As an extreme case, some myocytes completely failed to elicit all-or-none AP in 8 mM [K+]o at 24{degree sign}C. Also amplitude and overshoot of AP were reduced by elevation of [K+]o (P<0.05). Although high [K+]o antagonizes the negative effects of high temperature on excitation threshold, the precipitous depression of the rate of AP upstroke and complete loss of excitability in some myocytes suggest that the combination of high temperature and high [K+]o will severely impair ventricular excitability in roach.
... To this end, we conducted natural and laboratory experiments to determine the effects of diurnal temperature fluctuations on Arctic char swimming performance and physiology. In the field, over the naturally occurring temperature range, we used the reflex action mortality predictor protocol (RAMP; Davis, 2010;Raby et al., 2012Raby et al., , 2013 to assess vital reflexes in migrating adults following a stressful event (handling and tagging) and used repeated swimming performance tests (Jain, Birtwell, & Farrell, 1998;Jain & Farrell, 2003) in migrating smolts to assess their ability to repeatedly perform fatiguing exercise. In the laboratory, we simulated a diurnal temperature fluctuation representative of the upper end of the current range encountered by migrating char, gave fish repeated exercise tests, and measured their oxygen consumption and several other physiological stress indicators. ...
... Rainbow trout were selected because their thermal physiology has been well studied (Farrell, 2007;Farrell, Gamperl, Hicks, Shiels, & Jain, 1996;Gamperl et al., 2002;Jain & Farrell, 2003), they can be reared under identical conditions to char, and like Arctic char, they are iteroparous and facultatively anadromous. 114.8°W; Figure 1). ...
The Arctic is warming at twice the global average rate; how native and non‐native anadromous fishes will respond remains largely unknown. Some native Arctic salmonids are already experiencing warm (>21°C), physically challenging migratory river conditions and large diurnal temperature fluctuations (>10°C).
We conducted field and laboratory experiments to determine how these extreme conditions may affect the capacity for migration in Arctic and temperate salmonids.
In adult migratory Arctic char, reflex impairment following a handling challenge increased with temperature, indicating more extensive fatigue. In Arctic char smolts, temperature did not affect initial critical swimming performance ( U max1 ), however, there was a threshold for repeat swimming performance ( U max2 ) near 20°C, above which recovery was impaired.
Following a simulated diurnal warming scenario (11–21°C), U max1 increased in rainbow trout and remained constant in Arctic char as in the field while U max2 remained constant in rainbow trout it was drastically reduced in Arctic char. Furthermore, at warm temperatures, Arctic char were unable to recover to routine levels of oxygen uptake after exercise, while rainbow trout were. Warming also had more pronounced effects on blood composition and plasma glucose and lactate concentration in Arctic char than in rainbow trout.
In general, rainbow trout, a temperate salmonid, had superior swimming performance, aerobic capacity, and warm tolerance than Arctic char, an Arctic salmonid.
The present flow and temperature regimes in some Arctic rivers may restrict migration of native salmonids by limiting their ability to recover from fatiguing exercise. Non‐native, temperate salmonids are likely better suited to overcome these particular physical and thermal challenges.
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... Heath and Hughes detected diminished heart function and venous oxygen deficiency in O. mykiss acutely exposed to 24-25 °C 70 . Following acclimation, Jain and Farrell observed impaired exercise recovery at 15 °C, Farrell et al. found diminished cardiac function at 18 °C and 22 °C, and Taylor et al. detected reduced aerobic swimming capacity at 18 °C[71][72][73] . There appears to be a latitudinal gradient of functional thermal tolerance for O. mykiss and that Piru Creek exhibit the highest functional thermal limits of any measured population.Figure 8.Locations of temperature data loggers in the Santa Clara River watershed with temperature data plotted for each location. ...
Fish habitat temperatures are increasing due to human impacts including climate change. For broadly distributed species, thermal tolerance can vary at the population level, making it challenging to predict which populations are most vulnerable to warming. Populations inhabiting warm range boundaries may be more resilient to these changes due to adaptation or acclimatization to warmer temperatures, or they may be more vulnerable as temperatures may already approach their physiological limits. We tested functional and critical thermal tolerance of two populations of wild Oncorhynchus mykiss near the species’ southern range limit and, as predicted, found population-specific responses to temperature. Specifically, the population inhabiting the warmer stream, Piru Creek, had higher critical thermal maxima and higher functional thermal tolerance compared to the population from the cooler stream, Arroyo Seco. Arroyo Seco O. mykiss are more likely to experience a limitation of aerobic scope with warming. Piru Creek O. mykiss, however, had higher resting metabolic rates and prolonged exercise recovery, meaning that they could be more vulnerable to warming if prey or dissolved oxygen become limited. Temperature varies widely between streams near the O. mykiss southern range limit and populations will likely have unique responses to warming based on their thermal tolerances and metabolic requirements.
... where S is the highest speed at which the fish swam for the full time period (cm s −1 ), ΔS is the velocity increment (12 cm s −1 ), T 1 is the prescribed period of swimming per speed (20 min), and T 2 is the time that the fish swam at the final speed (min). U crit was corrected for the solid blocking effect if the cross-sectional area of the fish was more than 10% of the swimming chamber (Jain & Farrell, 2003). ...
Flow stimulation before release into the wild may contribute to improved survivability of farmed fish. However, the effects of flow stimulation on the survival rate of fish depend on the fish species and exercise regime, such as exercise type, duration, and intensity. In this study, juvenile Percocypris pingi swam for 18 h per day for 8 weeks under different water speeds, 3 cm s-1 (control) and 1, 2, and 4 body lengths (bl) s-1 , at 20°C. Then, parameters related to the growth rate, swimming capacity, spontaneous activity, and immune function were measured. We found that (1) continuous flow stimulation had no significant influence on the growth but was conducive to the increase in the relative carcass mass; (2) continuous flow stimulation at 2 or 4 bl s-1 enhanced the aerobic swimming capacity (Ucrit ), which may be due to an increase in anaerobic exercise capacity (endurance time) rather than to changes in maximum metabolic rate and aerobic scope; (3) continuous flow stimulation at 4 bl s-1 led to a significant increase in spontaneous activity, which was mainly due to the higher percent time spent moving as compared with the controls; and (4) continuous flow stimulation at 2 bl s-1 may contribute to improving the nonspecific immune parameter (lysozyme activity) in juvenile P. pingi. Our findings suggest that continuous flow stimulation at 2 or 4 bl s-1 for 18 h per day for 56 days at 20°C before release in wild may be a suitable training regime for improving the survival rate of cultured juvenile P. pingi.
... Contaminated water typically reduces U crit indicating compromised performance (Corriere et al., 2020;De Boeck et al., 2006;Farrell, 2008;McGeer et al., 2000;McKenzie et al., 2007;Monteiro et al., 2021;Sahota et al., 2021;Wilson et al., 1994;Yu et al., 2015). Repeating the exercise challenge after a short recovery period can indicate the level of recovery after a first U crit measurement, and a contaminant effect can be detected by a lowering of the second U crit measurement (Farrell et al., 1998;Jain and Farrell, 2003;McKenzie et al., 2007). While the U crit protocol and other swimming speed measurements are standalone bioindicators, adding respirometry allows MMR to be measured. ...
An endless list of new chemicals are entering nature, which makes it an impossible task to assess all possible mixture combinations at all possible concentrations and conditions that are leading to the ubiquitous anthropogenic impacts on the aquatic environment resulting from deteriorating water quality. Therefore, ecotoxicology is moving more toward a mechanistic understanding of toxicological processes, using trait-based approaches and sublethal molecular and physiological endpoints to understand the mode of action of pollutants and the adverse outcomes at the organismal and population level. These molecular and physiological endpoints can be used as biomarkers, applicable in the field. This brings ecotoxicological research much closer to conservation physiology. Understanding the relationships between chemical reactivity in the water and in organisms, and assessing the consequences at higher levels, allows conservation physiologists and managers to take the right restoration measures for an optimal improvement of the aquatic habitats of concern. In this chapter we discuss the role which the promising approach of mechanistic-based Adverse Outcome Pathways (AOPs) can play in ecotoxicological research. It studies a pathway of events, from the direct interaction of a chemical with a molecular target, through subsequent intermediate events at cellular, tissue, organ and individual organism levels which then result in an Adverse Outcome (AO) relevant to ecotoxicological risk assessment and regulatory decision-making. In this context, we also discuss the importance of modeling, including bioavailability based and effect based models. Finally, we reflect on the possibilities that meta-analysis has to offer to detect unifying physiological processes, as well as interesting outliers.
... When the desired temperature was reached, the preparations were allowed to equilibrate at this temperature for 30 min and optical mapping was done at both temperatures. Since the concentration of potassium in blood plasma of the fish is affected by temperature and increases with exercise and warming (Haux and Larsson, 1982;Korcock et al., 1988;Jain and Farrell, 2003), AV preparations were mapped at 27 • C under the perfusion of external saline solution with physiological ([K + ] o = 4 mM) and elevated potassium ([K + ] o = 8 mM). Thus, the preparations utilized in optical mapping experiments after the temperature maneuvers were consequentially perfused in solutions with two different K + concentrations at higher (27 • C) temperature. ...
At critically high temperatures, atrioventricular (AV) block causes ventricular bradycardia and collapse of cardiac output in fish. Here, the possible role of the AV canal in high temperature-induced heart failure was examined. To this end, optical mapping was used to measure action potential (AP) conduction in isolated AV junction preparations of the rainbow trout (Oncorhynchus mykiss) heart during acute warming/cooling in the presence of 4 or 8 mM external K⁺ concentration. The preparation included the AV canal and some atrial and ventricular tissue at its edges, and it was paced either from atrial or ventricular side at a frequency of 0.67 Hz (40 beats min⁻¹) to trigger forward (anterograde) and backward (retrograde) conduction, respectively. The propagation of AP was fast in atrial and ventricular tissues, but much slower in the AV canal, causing an AV delay. Acute warming from 15 °C to 27 °C or cooling from 15 °C to 5 °C did not impair AP conduction in the AV canal, as both anterograde and retrograde excitations propagated regularly through the AV canal. In contrast, anterograde conduction through the AV canal did not trigger ventricular excitation at the boundary zone between the AV canal and the ventricle when extracellular K⁺ concentration was raised from 4 mM to 8 mM at 27 °C. Also, the retrograde conduction was blocked at the border between the AV canal and the atrium in high K⁺ at 27 °C. These findings suggest that the AV canal is resistant against high temperatures (and high K⁺), but the ventricular muscle cannot be excited by APs coming from the AV canal when temperature and external K⁺ concentration are simultaneously elevated. Therefore, bradycardia at high temperatures in fish may occur due to inability of AP of the AV canal to trigger ventricular AP at the junctional zone between the AV canal and the proximal part of the ventricle.
... where U (cm/s) is the highest velocity at which fish swam for the full-time interval DU, m/s) is the speed step, t (min) is the time to fatigue during the last velocity step, and Dt (min) is the time step (20 min). The body cross-sectional area of the test fish in this study did not exceed 10% of the cross-sectional area of the swimming area, minimizing the need for a U crit correction (Jain, 2003;Wang, 2009). The recovery ratio (R) of Ucrit (cm/s) was a measure of a fish's ability to recover from fatigue. ...
Differences in individual personality are common amongst animals, which can play an ecological and evolutionary role given links to fitness. Personality affects animal life processes and outputs (e.g., behavior, life history, growth, survival, reproduction), and has become a common theme in animal behavioral ecology research. In the present study, we used Siberian Sturgeon to explore how personality traits of boldness and shyness are related to swimming performance, post exercise recovery and phenotypic morphology. Firstly, our results indicated that the Siberian sturgeon juveniles of shyness were better swimmers, validating evolutionary biology trade-off theory. The critical swimming speed (U crit ) of the shy groups was higher than that of the bold groups. Secondly, the shy groups were more resilient after exercise fatigue. The swimming fatigue recovery ability, the glucose and lactic acid concentration recovery ability of shy groups were greater than that of bold groups. Thirdly, the shy groups were more streamlined. Compared with bold groups, shy groups had smaller caudate stalk lengths, caudate stalk heights, superior caudal lobes, and inferior caudal lobes. In general, we demonstrated that shy Siberian sturgeon had better swimming performance from physiology and morphology. These research results further enrich the theoretical viewpoints of fish behavior biology, more importantly, which provided a good example for studying the relationship between sturgeon’s “personality” and swimming performance.
... Such migration delays likely relate in part to 'repaying' an oxygen debt (Lee et al., 2003) from anaerobic swimming while escaping before continuing their migration. Complete recovery from full exhaustion may take up to 24 h (Zhang et al., 2018), but fatigued salmon can resume swimming much sooner (after 40-60 min; Jain et al., 1998;Lee et al., 2003;Jain and Farrell, 2003;Wagner et al., 2006). The ~ 6 h delay to negotiate the Seton Dam fishway is consistent with these sorts of known recovery Fig. 3. Temperature of migration through both Seton and Anderson lakes. ...
Two hypotheses were tested concerning the consequences to adult sockeye salmon (Oncorhynchus nerka) of escape from commonly used fishing gear (gillnet, seine net and tangle net). First, by experimentally exposing 214 fish to three commonly used fishing gear types (gillnets, tangle nets, or seine nets) and releasing to complete migration after PIT-tagging, we tested the hypothesis that migration success and behaviour are differentially impacted according to the type of fishing gear interaction and escape. Also, by fitting salmon with thermal loggers, we tested whether salmon behaviourally selected cooler lake water following an escape encounter. Migration success was unaffected after escape from the simulated gear types compared to control fish. Surviving sockeye salmon that had gillnet or seine net encounter, but not a tangle net encounter, on average took approximately 2 days longer to migrate to the spawning area (averaging 14.7 days and 14.9 days, respectively) compared to control fish (12.6 days). Furthermore, escaped fish migrated at cooler temperatures through a lake system (average of 14.0 °C) compared to control fish (15.3 °C), which would reduce their absolute cost of transport during this migration by reducing the standard metabolic rate by about 10%. Consequently, in addition to demonstrating that fish escapement from a fishing gear will alter their subsequent migration behaviour, we introduce the possibility that the associated increase in energy expenditure and migration delay can be partially compensated for by behavioural selection of cooler water, if it is available, to lower basic energy turnover in a fish that is entirely reliant on energy stores to fuel its spawning migration.
... This characteristic would make it possible to use them in the diet of different fish species as well as make them tolerant to the different annual climatic seasons. The seasonal changes in water temperature can be extremely different for cold-water and warm-water species, they can range from below 5 • C to 19 • C and 16 • C to 39 • C, respectively [89,90]. ...
Dietary probiotic supplementation has the potential to enhance the health of fish and their disease resistance. In this study, some properties of ten Lactiplantibacillus plantarum strains have been evaluated, for their potential use as probiotics in freshwater fish diet. In particular, antimicrobial activity, antioxidant activity, the potentiality to survive the gastrointestinal transit and persist in the intestine, were evaluated in vitro. The experimental tests were carried out at 15 °C and 30 °C to determine the suitability of these lactic acid bacteria to be used as probiotics in the diet of fish grown at different temperatures. The results demonstrated that the evaluated Lp. plantarum strains, which often have significant differences among themselves, are characterized by important functional characteristics such as cell surface properties (auto-aggregation and hydrophobicity), ability to produce antioxidant substances, capacity to survive in the presence of 0.3% bile salts and acidic environment (2.5 pH), antagonistic activity against some fish opportunistic pathogens (A. salmonicida, Ps. aeruginosa, E. coli and C. freundii) and other unwanted bacteria present in fish products (S. aureus and L. innocua). The outcomes suggest that these Lp. plantarum strains may be candidates as probiotics in warm- and cold-water aquaculture.
... Temperature has been coined the "master" factor (Fry, 1971) due to its strong influence on fish physiology and behaviour (Pacific salmon e.gJain & Farrell, 2003;Jeffries et al., 2012Kocan et al., 2009;MacNutt et al., 2004), including the potential to exacerbate fishery impacts (Gale et al., 2013). Elevated river temperatures similar to those applied in this study are already impacting sockeye salmon populations during freshwater migrations (Patterson et al., 2007). ...
Incorporating host-pathogen(s)-environment axes into management and conservation planning is critical to preserving species in a warming climate. However, the role pathogens play in host stress resilience remains largely unexplored in wild animal populations. We experimentally characterized how independent and cumulative stressors (fisheries handling, high water temperature) and natural infections affected the health and longevity of released wild adult sockeye salmon (Oncorhynchus nerka) in British Columbia, Canada. Returning adults were collected before and after entering the Fraser River, yielding marine- and river-collected groups, respectively (N=185). Fish were exposed to a mild (seine) or severe (gill net) fishery treatment at collection, and then held in flow-through freshwater tanks for up to four weeks at historical (14°C) or projected migration temperatures (18°C). Using weekly nonlethal gill biopsies and high-throughput qPCR, we quantified loads of up to 46 pathogens with host stress and immune gene expression. Marine-collected fish had less severe infections than river-collected fish, a short migration distance (100 km, 5-7 d) that produced profound infection differences. At 14°C, river-collected fish survived 1-2 weeks less than marine-collected fish. All fish held at 18°C died within 4 weeks unless they experienced minimal handling. Gene expression correlated with infections in river-collected fish, while marine-collected fish were more stressor-responsive. Cumulative stressors were detrimental regardless of infections or collection location, likely due to extreme physiological disturbance. Because river-derived infections correlated with single stressor responses, river entry likely decreases stressor resilience of adult salmon by altering both physiology and pathogen burdens, which redirect host responses toward disease resistance.
... As poikilothermic organisms, the body temperature and physiology of fish are directly tied to ambient water temperatures that may change by more than 10°C due to seasonal variation, fish migration, or microclimates (142,143). Immune response kinetics are directly influenced by temperature and thermal stress may inhibit or suppress the host immune system (144), altering the nature or course of the immune response (145). ...
Myxozoans are microscopic, metazoan, obligate parasites, belonging to the phylum Cnidaria. In contrast to the free-living lifestyle of most members of this taxon, myxozoans have complex life cycles alternating between vertebrate and invertebrate hosts. Vertebrate hosts are primarily fish, although they are also reported from amphibians, reptiles, trematodes, mollusks, birds and mammals. Invertebrate hosts include annelids and bryozoans. Most myxozoans are not overtly pathogenic to fish hosts, but some are responsible for severe economic losses in fisheries and aquaculture. In both scenarios, the interaction between the parasite and the host immune system is key to explain such different outcomes of this relationship. Innate immune responses contribute to the resistance of certain fish strains and species, and the absence or low levels of some innate and regulatory factors explain the high pathogenicity of some infections. In many cases, immune evasion explains the absence of a host response and allows the parasite to proliferate covertly during the first stages of the infection. In some infections, the lack of an appropriate regulatory response results in an excessive inflammatory response, causing immunopathological consequences that are worse than inflicted by the parasite itself. This review will update the available information about the immune responses against Myxozoa, with special focus on T and B lymphocyte and immunoglobulin responses, how these immune effectors are modulated by different biotic and abiotic factors, and on the mechanisms of immune evasion targeting specific immune effectors. The current and future design of control strategies for myxozoan diseases is based on understanding this myxozoan-fish interaction, and immune-based strategies such as improvement of innate and specific factors through diets and additives, host genetic selection, passive immunization and vaccination, are starting to be considered.
... Elevated circulating cortisol levels at higher temperatures post-exposure to an exhaustive exercise stressor have been found in several other studies (e.g. Jain and Farrell, 2003;Suski et al., 2003Suski et al., , 2006Meka and McCormick, 2005;McLean et al., 2016). For example, rainbow trout (Oncorhynchus mykiss) in southwest Alaska that were angled during a warmer year compared with a cooler year (13.2 versus 9.8°C) exhibited significantly increased plasma cortisol concentrations post-angling event (Meka and McCormick, 2005). ...
Understanding the resilience of ectotherms to high temperatures is essential because of the influence of climate change on aquatic ecosystems. The ability of species to acclimate to high temperatures may determine whether populations can persist in their native ranges. We examined physiological and molecular responses of juvenile brook trout (Salvelinus fontinalis) to six acclimation temperatures (5, 10, 15, 20, 23 and 25°C) that span the thermal distribution of the species to predict acclimation limits. Brook trout exhibited an upregulation of stress-related mRNA transcripts (heat shock protein 90-beta, heat shock cognate 71 kDa protein, glutathione peroxidase 1) and downregulation of transcription factors and osmoregulation-related transcripts (nuclear protein 1, Na+/K+/2Cl− co-transporter-1-a) at temperatures ≥20°C. We then examined the effects of acclimation temperature on metabolic rate (MR) and physiological parameters in fish exposed to an acute exhaustive exercise and air exposure stress. Fish acclimated to temperatures ≥20°C exhibited elevated plasma cortisol and glucose, and muscle lactate after exposure to the acute stress. Fish exhibited longer MR recovery times at 15 and 20°C compared with the 5 and 10°C groups; however, cortisol levels remained elevated at temperatures ≥20°C after 24 h. Oxygen consumption in fish acclimated to 23°C recovered quickest after exposure to acute stress. Standard MR was highest and factorial aerobic scope was lowest for fish held at temperatures ≥20°C. Our findings demonstrate how molecular and physiological responses predict acclimation limits in a freshwater fish as the brook trout in the present study had a limited ability to acclimate to temperatures beyond 20°C.
... However, anthropogenic changes to the climate and local hydrology of estuaries can also alter these gradients, thus impacting habitat suitabil-ity for estuarine species (Gillanders et al. 2011, Brown et al. 2013, James et al. 2013, Robins et al. 2016, Muhling et al. 2018. For example, temperature increases metabolic rates and subsequent growth rates (Jain & Farrell 2003, Green & Fisher 2004) until thermal limits are reached, after which growth is suppressed (Houde 1989, Pörtner & Farrell 2008, Neuheimer et al. 2011, Wenger et al. 2016, Dahlke et al. 2020, Neubauer & Andersen 2020. Similarly, changes in salinity can influence metabolic demands, contingent upon the osmoregulatory physiology of a given species (Lankford & Targett 1994, Baltz et al. 1998, Labonne et al. 2009, and turbidity can enhance growth and survival by reducing predation risk and enhancing foraging success of larval fishes (Blaber & Blaber 1980, Cyrus & Blaber 1987, Gregory 1993, Rypel et al. 2007, Tigan et al. 2020. ...
In estuaries, fluctuating environmental conditions exact strenuous physiological demands on the fishes that inhabit these oft-impacted areas, including the Critically Endangered delta smelt Hypomesus transpacificus in California (USA). Using an archive of otoliths spanning 2011-2019, we examined how growth rates of wild subadult delta smelt vary ontogenetically, regionally, and in relation to variation in the physical environment during late-summer and fall in the upper San Francisco Estuary. Recent growth rates were quantified using otolith increment analysis and modeled as functions of both intrinsic (age) and extrinsic (temperature, salinity, clarity, and region) factors using a suite of generalized additive models. Age explained 60% of the variation in log 10 -transformed growth rates, which peaked at 50-80 d post hatch. Overall, age-adjusted growth rates declined at temperatures >20°C, increased with practical salinity values of 0-4, and exhibited interactive patterns with water clarity. Growth rates appeared highest in the West and Central Delta, and lowest in the North Delta, also corresponding with patterns in environmental conditions. Here, we provide new evidence for how vital rates of wild delta smelt vary spatially and in relation to abiotic environmental variation. Such otolith-based growth reconstructions often provide the first direct look at how the vital rates of wild fish respond to environmental variation in situ , and how future changes are likely to affect the dynamics of wild populations.
... ILOS, however, is quite sensitive to the rate at which ambient DO is reduced, in part, because glycogen stores are finite [66][67][68] and, in part, because the accumulation of metabolic wastes from glycolysis may eventually reach toxic thresholds. For example, exceeding the plasma lactate threshold suggested for fish (~20 mmol L −1 ; [69,70]) seems to signal delayed mortality [71,72]. Indeed, some anoxia-tolerant ectotherms have evolved extraordinary strategies to mitigate the accumulation of these metabolic wastes. ...
The utility of measuring whole-animal performance to frame the metabolic response to environmental hypoxia is well established. Progressively reducing ambient oxygen (O2) will initially limit maximum metabolic rate as a result of a hypoxemic state and ultimately lead to a time-limited, tolerance state supported by substrate-level phosphorylation when the O2 supply can no longer meet basic needs (standard metabolic rate, SMR). The metabolic consequences of declining ambient O2 were conceptually framed for fishes initially by Fry’s hypoxic performance curve, which characterizes the hypoxemic state and its consequences to absolute aerobic scope (AAS), and Hochachka’s concept of scope for hypoxic survival, which characterizes time-limited life when SMR cannot be supported by O2 supply. Yet, despite these two conceptual frameworks, the toolbox to assess whole-animal metabolic performance remains rather limited. Here, we briefly review the ongoing debate concerning the need to standardize the most commonly used assessments of respiratory performance in hypoxic fishes, namely critical O2 (the ambient O2 level below which maintenance metabolism cannot be sustained) and the incipient lethal O2 (the ambient O2 level at which a fish loses the ability to maintain upright equilibrium), and then we advance the idea that the most useful addition to the toolbox will be the limiting-O2 concentration (LOC) performance curve. Using Fry & Hart’s (1948) hypoxia performance curve concept, an LOC curve was subsequently developed as an eco-physiological framework by Neil et al. and derived for a group of fish during a progressive hypoxia trial by Claireaux and Lagardère (1999). In the present review, we show how only minor modifications to available respirometry tools and techniques are needed to generate an LOC curve for individual fish. This individual approach to the LOC curve determination then increases its statistical robustness and importantly opens up the possibility of examining individual variability. Moreover, if peak aerobic performance at a given ambient O2 level of each individual is expressed as a percentage of its AAS, the water dissolved O2 that supports 50% of the individual’s AAS (DOAAS-50) can be interpolated much like the P50 for an O2 hemoglobin dissociation curve (when hemoglobin is 50% saturated with O2). Thus, critical O2, incipient lethal O2, DOAAS-50 and P50 and can be directly compared within and across species. While an LOC curve for individual fish represents a start to an ongoing need to seamlessly integrate aerobic to anaerobic capacity assessments in a single, multiplexed respirometry trial, we close with a comparative exploration of some of the known whole-organism anaerobic and aerobic capacity traits to examine for correlations among them and guide the next steps.
... Temperature has been coined the "master" factor (Fry, 1971) due to its strong influence on fish physiology and behaviour (Pacific salmon e.gJain & Farrell, 2003;Jeffries et al., 2012Kocan et al., 2009;MacNutt et al., 2004), including the potential to exacerbate fishery impacts (Gale et al., 2013). Elevated river temperatures similar to those applied in this study are already impacting sockeye salmon populations during freshwater migrations (Patterson et al., 2007). ...
Incorporating host-pathogen(s)-environment axes into management and conservation planning is critical to preserving species in a warming climate. However, the role pathogens play in host stress resilience remains largely unexplored in wild animal populations. We experimentally characterized how independent and cumulative stressors (fisheries handling, high water temperature) and natural infections affected the health and longevity of released wild adult sockeye salmon (Oncorhynchus nerka) in British Columbia, Canada. Returning adults were collected before and after entering the Fraser River, yielding marine- and river-collected groups, respectively. Fish were exposed to a mild (seine) or severe (gill net) fishery treatment at collection, and then held in circulating freshwater tanks for up to four weeks at historical (14°C) or projected migration temperatures (18°C). Using weekly nonlethal gill biopsies and high-throughput qPCR, we quantified loads of up to 46 pathogens with host stress and immune gene expression. Marine-captured fish had less severe infections than river-captured fish, a short migration distance (100 km, 5-7 d) that produced profound infection differences. At 14°C, river-collected fish survived 1-2 weeks less than marine-collected fish. All fish held at 18°C died within 4 weeks unless they experienced minimal handling. Gene expression correlated with infections in river-collected fish, while marine-collected fish were more stressor-responsive. Cumulative stressors were detrimental regardless of infections or collection location, likely due to extreme physiological disturbance. Because river-derived infections correlated with single stressor responses, river entry likely decreases stressor resilience of adult salmon by altering both physiological status and pathogen burdens, which redirect host responses toward disease resistance.
... Rainbow trout populations are found across North American regions which experience seasonal climatic fluctuations. Changes to abiotic factors (such as temperature and sunlight) are known to affect numerous fish behavioral and physiological parameters, including fish feeding rates, activity, spawning behavior, and cellular nutrient dynamics (Gordon and McLeay, 1978;Berg and Bremset, 1998;St-Pierre et al., 1998;Bremset, 2000;Jain, 2003). Further, pre-fasting diets have been shown to have a profound impact on fish metabolism at the onset of fasting (Hilton, 1982). ...
Hydraulic fracturing flowback and produced water (FPW) is a highly complex and heterogenous wastewater by-product of hydraulic fracturing practices. To date, no research has examined how FPW exposure to freshwater biota may affect energetic homeostasis following subsequent induction of detoxification processes. Rainbow trout (Oncorhynchus mykiss) were acutely exposed for 48 h to either 2.5% or 7.5% FPW, and hepatic metabolism was assessed either immediately or following a 3-week recovery period. Induction of xenobiotic metabolism was observed with an 8.8-fold increase in ethoxyresorufin-O-deethylase (EROD) activity after 48 h exposure to 7.5% FPW, alongside a 10.3-fold increase in the mRNA abundance of cyp1a, both of which returned to basal level after three weeks. Glucose uptake capacity was elevated by 6.8- and 12.9-fold following 2.5% and 7.5% FPW exposure, respectively, while alanine uptake was variable. Activity measurements and mRNA abundance of key enzymes involved in hepatic metabolism indicated that aerobic metabolism was maintained with exposure, as was glycolysis. Gluconeogenesis, as measured by phosphoenolpyruvate carboxykinase (PEPCK) activity, decreased by ~30% 48 h following 2.5% FPW exposure and ~20% 3 weeks after 7.5% FPW exposure. The abundance of pepck mRNA activity followed similar, yet non-significant, trends. Finally, a delayed increase in amino acid catabolism was observed, as glutamate dehydrogenase (GDH) activity was increased 2-fold in 7.5% FPW exposed fish when compared to saline control fish at the 3-week time point. We provide evidence to suggest that although hepatic metabolism is altered following acute FPW exposure, metabolic homeostasis generally returns 3-weeks post-exposure.
... Repeat swimming performance testing is a useful, non-invasive and ecologically relevant tool for monitoring the fitness of fish (Jain et al., 1998;Jain & Farrell, 2000;Kieffer & May, 2020;Nelson et al., 2015). Critical swimming speed (U crit ) is a useful measure of swimming performance because it conveys important information regarding ability to forage, escape predation, and maintain position (Brett, 1964;Ward et al., 2003;Starrs et al., 2011;Penny & Kieffer, 2019). ...
The swimming performance of juvenile rock carp (Procypris rabaudi, Tchang) subjected to repeated fatigue exercise was studied using a flume-type respirometer at 20°C. The critical swimming speed (Ucrit) and oxygen consumption rate (MO2) of juvenile rock carp were measured during two successive stepped velocity tests, following
a 60 min rest interval. Ucrit of rock carp was giving a recovery ratio (Rr) of 92.64%, and exertion exercise decreases Ucrit. When MO2 was plotted as a linear function of U, the slope for trial 1 was 1.06 and 1.50 for trial 2, indicating a decreasing in swimming efficiency. The maximum metabolic rate (MMR) increased from 17.06 ± 1.14 mmol
O2/(kg·hr) to 19.14 ± 1.23 mmol O2/(kg·hr), and the exercise post oxygen consumption rate (EPOC) increased from 9.00 to 9.65 mmol O2/kg. Repeated fatiguing exercise increased both the aerobic and anaerobic cost of reaching Ucrit, but anaerobic metabolism accounted for a larger proportion in the trial 2. The data investigation on
the swimming performance and the physiological response to fatigue provide important design criteria for fishways.
... Salmon parr were Individually tagged fish were acclimated to one of four thermal profiles for 11 weeks, 16 C (n = 17), 18.5 C (n = 16), 21 C (n = 16) and 16 C-21 C diel cycle (n = 16; 0.42 C h -1 for 12 h) to represent a natural diel thermal cycle in the Miramichi River (Breau & Caissie, 2012;Caissie et al., 2014). Length and weight were recorded approximately every 5 weeks and used to calculate the growth rate and condition factor (CF) using the following equation: (Jain and Farrell 2003) was conducted by increasing the flow in the chamber to 50% of the estimated U crit (determined by earlier trials) within the first 5 min and then increasing the flow by 15% of the estimated U crit every 20 min until the fish was exhausted. Immediately after the fish was exhausted, the rate of oxygen consumption was measured in 30 s increments for 10 min at the resting flow of 15 cm s −1 . ...
Typically, laboratory studies on the physiological effects of temperature are conducted using stable acclimation temperatures. However, information extrapolated from these studies may not accurately represent wild populations living in thermally variable environments. Our objective was to compare the growth, metabolism, and swimming performance of wild Atlantic salmon exposed to cycling 16‐21oC, and stable 16oC, 18.5oC, 21oC acclimation temperatures. Growth rate, metabolic rate, swimming performance, and anaerobic metabolites did not change among acclimation groups, suggesting that within Atlantic salmon's thermal optimum range, temperature variation has no effect on these physiological properties.
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... Further, fatigue can influence subsequent swimming performance and prevent successful migration (Katopodis et al., 2019). Most existing references on the effect of exercise fatigue on subsequent swimming performance are for Salmonidae and Acipenser Jain and Farrell, 2003;Cai et al., 2015;Fang et al., 2017) and data on Cyprinidae are limited. These references focus on the effect of prolonged swimming on subsequent prolonged swimming, but the effects of burst swimming and exercise fatigue on subsequent burst swimming is limited. ...
Fish swimming behavior is important for their survival. Burst swimming, prolonged swimming, and their effect on each other were examined for Gymnocypris potanini firmispinatus. Test fish were randomly assigned to two groups, one group was tested for critical swimming speed (Ucrit), and the other was tested for burst speed (Uburst). After a 30-min recovery period, both groups were subjected to Uburst testing. The Uburst value measured following the Ucrit test was termed Uburst-c and Uburst-b was measured following the initial Uburst test. Results include two primary findings. (1) There were significant differences between Uburst and Uburst-c, and between Uburst and Uburst-b, indicating that the effect of fatigue from both prolonged and burst swimming on subsequent burst swimming performance is significant. (2) The recovery ratio after fatigue resulting from prolonged swimming was significantly lower than the recovery ratio after fatigue resulting from burst swimming. The differences between Uburst-c and Uburst-b was not significant. Therefore, whether or not prolonged swimming leads to deeper fatigue than burst swimming will require additional research. The findings from this study on prolonged and burst swimming and their effects on subsequent burst swimming will support continued improvement of fishway design.
... Swimming performance is an important trait and can be related to predator avoidance, foraging and migration (Anglea et al., 2004;Perry et al., 2013;Walker et al., 2016). U crit is a standard and commonly used performance metric to evaluate aerobic swimming performance in fishes (Farrell, 2008;Jain & Farrell, 2003). In this study, we used a 30 l Brett-style swim-tunnel (Loligo Systems, Viborg, Denmark; www. ...
In this study, we investigated the effects of acoustic tag implantation on standard and routine metabolic rate (SMR and RMR, estimated via oxygen consumption), critical swimming speed (Ucrit), survival and growth in juveniles of rainbow trout Oncorhynchus mykiss and lake trout Salvelinus namaycush. Tag burdens ranged from 1.8 to 7.5 % across the two species. Growth rates in acoustic‐tagged fish were equal to or higher than those in other treatments. Acoustic‐tagged S. namaycush had a marginally lower Ucrit than controls but that effect was not replicated in the O. mykiss experiment. Tagging did not have clear effects on SMR but there was an interaction whereby SMR and RMR tended to increase with time since surgery in tagged O. mykiss but not in other treatments (the same trend did not occur in S. namaycush). Survival was high across treatments (mean 98% survival among O. mykiss treatments, 97.5% among S. namaycush treatments). There were no statistically significant effects of relative tag burden (% of body mass) except for a weak negative relationship with growth rate (across species) and a weak positive relationship with Ucrit but only in the O. mykiss . Collectively, our findings suggest there were minor, context‐dependent effects of acoustic tagging in juvenile S. namaycush and O. mykiss during an eight‐week laboratory experiment. Further research will be required to assess whether tagging can cause meaningful behavioural effects in these species in captivity or in the wild and whether there is a tag burden threshold above which deleterious effects consistently occur. This article is protected by copyright. All rights reserved.
... While no previous studies have measured fine-scale swim speed of the same fish in both summer and winter in nature, this is wellpredicted by lab studies measuring swim speed under both warm and cold conditions; Webb (1978) found the maximum velocity of juvenile rainbow trout increased with temperature almost twofold (from 0.99 to 1.71 m·s −1 ) from 5 to 15°C, remaining constant thereafter up to 25°C. Jain and Farrell (2003) similarly found U crit to increase linearly among adult rainbow trout from 5 to 17°C. While colder conditions physiologically limit swim speeds, it also makes ecological sense that rainbow trout would reduce overall swim speed to conserve energy in winter when prey availability is low. ...
The fine-scale behavioural activities of rainbow trout (Oncorhynchus mykiss) in nature are not well understood, but are of importance for identifying interactions with the ecosystem and of interest to conservationists and recreational anglers. We have undertaken a high-resolution acoustic telemetry study to identify the distinct movement patterns of 30 rainbow trout in a freshwater lake, specifically examining swim speed, area of movement, and site preference in both summer and winter. Activity levels were reduced in winter compared with summer across all fish, but ranking of individuals was consistent. In summer, 16/30 fish displayed diel movement, in which they travelled to a different area of the lake at dawn and returned at dusk, while other fish maintained their site preference regardless of the time of day or swam more randomly throughout the lake. These patterns were minimized in winter, where there was a reduction in cross-lake movement under ice and only 4/30 fish displayed diel movement. Winter conditions may limit the capability (physiological limitations) and (or) motivation (prey availability) for diel behaviours observed in summer.
... Fish fatigue must be considered in the design of fish passage systems. Fish need to rest when fatigued before continuing through a fishway and incomplete recovery decreases swimming capability (Jain and Farrell, 2003;Cai et al., 2014). For example, the rate of upstream movement of several Neotropical migratory species decreased with ascent distance in a 10 km long fish passage canal (Makrakis et al., 2011). ...
The rapid decline in sturgeon populations is largely a result of human activities, especially the proliferation of hydraulic structures and lack of fish passage systems effective for sturgeon. This review highlights: (1) the importance of sturgeon conservation; (2) the need for data on swimming performance, including capability, metabolism and kinematics; (3) the relevance and limitations of swimming performance data in designing fish passage systems; (4) the need for experiments to develop sturgeon fishways that better reflect natural conditions. A proper understanding of swimming performance is crucial for designing effective fish passage systems. Although swimming performance and fish passage have been investigated for decades, knowledge and results have been limited by biological, methodological and analytical restrictions. To continue advancing passage effectiveness, continued research is necessary on sturgeon swimming performance and its interface with complex fishway hydraulics.
... Exhaustion was defined as the time at which the fish failed to swim away from the rear grid after 20 s of contact (Jain, 2003). Critical swimming speed was calculated according to the formula: ...
Bighead carp Hypophthalmichthys nobilis and silver carp H. molitrix (together, the bigheaded carps) are invasive fishes in North America that have resulted in substantial negative effects on native fish communities and aquatic ecosystems. Movement and behavior of adult bigheaded carps has been studied previously using telemetry, while similar studies with juvenile bigheaded carps have yet to be attempted. Recent technological advances in telemetry transmitters has increased the availability of tags sufficiently small enough to implant in juvenile carps. However, the effects of surgical implantation of telemetry tags on juvenile bigheaded carps have not been evaluated. We determined tag retention and survival associated with surgical implantation of acoustic telemetry tags into juvenile bighead carp (range 128-152 mm total length) at three temperatures (13°C, 18°C, and 23°C). In addition, we assessed the effect of surgically implanted transmitters on the fitness, defined as changes in weight or critical swimming speed, of carp implanted with transmitters. Survival was high among tagged fish (85 percent) with 47 percent of tags retained at the conclusion of the 45-day study. No substantial decline in fitness of the fish was observed in tagged fish compared to untagged fish.
... Generally, potassium levels in fish plasma either rise or are maintained at a constant level with increasing temperature (Burton 1986). Plasma potassium levels have been reported to increase in rainbow trout just before maximum exercise, especially at elevated temperatures, as high intensity exercise elicits potassium loss from the muscle (Jain & Farrell 2003). It is possible that the elevated potassium levels observed in sea bream during the recovery period might reflect a transient mismatch between the lack of an adequate nutritional status and the increased metabolism and overall activity induced by the rise in temperature. ...
There are currently no standard diets or practices to counteract or ameliorate the growth arrest and extremely poor feed conversion rates (FCR) in gilthead sea bream Sparus aurata caused by low water
temperatures. The present study analysed the effects of reducing dietary lipid content from 18 to 14% during a temperature fluctuation period. Temperature was gradually reduced from 22° to 14°C over a period of 5 d, and maintained at this low temperature for a further 45 d before gradual recovery over 7 d to 22°C under controlled conditions, avoiding other stressors often present in cage culture conditions. Decreasing dietary lipid content at an elevated temperature (22°C) did not significantly affect the standard growth rate or FCRs of the sea bream, indicating a possibility to reduce the dietary energy during the months before winter. Although cold-induced growth arrest and metabolic depression were unavoidable, a well-formulated, lowlipid
diet adequately met the low energy demands at low temperatures. Analysis of plasma metabolites and liver enzyme activities demonstrated a reorganisation of liver metabolism, mainly in fish on a low-lipid diet. Recovery from low temperatures was delayed, with a higher dietary lipid content required for optimal liver condition, and mineral supplementation to maintain osmoregulation and bone formation. Our results provide useful information for fish producers and researchers, suggesting that dietary lipid contents should be reduced to allow fish to better cope with low temperatures, and that improved diets with higher lipid content are required for recovery from low temperatures.
... This leads to serious ion imbalances and potentially acute death, but latent mortality can also occur from the inability to fully recover from exhaustion (Black, 1958;Kieffer, 2000). Fish that do survive the physiological imbalances can lose equilibrium (Danylchuk et al., 2007) and exhibit impaired swimming abilities (Jain & Farrell, 2003), both of which increase susceptibility to predation (See Section 2.5; Brownscombe et al., 2013;Raby, Packer, et al., 2014). ...
Discarding non‐target fish from commercial fisheries is controversial and has been a persistent concern for fisheries managers globally. Discard management strategies typically begin by understanding mortality rates among discarded fish, a challenging task given the dynamic, highly context‐specific nature of fisheries. An alternative is to develop our knowledge of how stressors operate by first understanding the causes of mortality that drive this context dependence. Particularly relevant to mitigation efforts is an understanding of how fish respond to the physical factors of fishing, such as the gear itself and methods of fishing and handling the gear. We provide a synthesis of how commercial fishing methods may influence discard mortality and outline means by which capture‐induced stress and injury can be mitigated for common commercial gear types, emphasizing method variants or alternatives during capture, handling, and release that could improve survival. This synthesis identifies exhaustion and injury as the most detrimental and ubiquitous stressors experienced by discarded fish, with few options for mitigating their effects. Trawls and hanging net fisheries are identified as the most harmful gears for by‐catch, characterized by high stress regardless of method variants and limited options for mitigation. Irrespective of gear type and type of stressor, minimizing durations of capture and handling and encouragement of good handling behaviour (e.g., during landing and sorting) will reduce the magnitude of stress and injury in fish, and ultimately increase survival.
... Exercise and handling stress in fish can cause a marked rise of [K + ]o up to 20 mmol L -1 (Wells et al., 1986). Furthermore, it has been found that the rise of [K + ]o is dependent on temperature and the thermal history of the fish (Jain and Farrell, 2003;Gale et al., 2013;Danylchuk et al., 2014). Since K + currents are important for maintaining RMP and repolarization of AP in excitable tissues, changes in [K + ]o are probably physiologically important in the regulation of cardiac and neural functions. ...
... The handling of fish prior to the hand-chase procedure might raise a concern that fish cannot reach the ṀO 2max post-stress. Salmonids, however, can reach ṀO 2max and maximum cardiac output in the second U crit test without full recoveries of ṀO 2, cardiac output and plasma lactate, presumably because the arterial and venous blood content can be replenished rapidly (Jain et al., 2003;Eliason et al., 2013). Hence, ṀO 2max derived by chasing fish to exhaustion should be valid. ...
... In our study, 64% of the fish still had plasma lactate concentrations exceeding 10 mmol/L after 4 h, and 14% had concentrations surpassing 20 mmol/L (Figure 7). This suggests that the Sockeye Salmon were still experiencing a high level of circulating lactate indicating muscle fatigue that may severely limit burst-swimming ability even 4 h after treatment and potentially reduce survival over the long term (Jain and Farrell 2003;Crossin et al. 2009). Our results show that >4 h was required for plasma cortisol (Figure 2) and plasma lactate ( Figure 1B) levels to return to basal values. ...
A variety of electronic tag types are routinely applied to fish to better understand migration biology. However, tagging procedures have the potential to affect the postrelease behaviour and survival of tagged individuals. In this study, wild adult Sockeye Salmon Oncorhynchus nerka from the Harrison River, British Columbia, were radio-tagged by gastric insertion or external attachment techniques immediately after capture to understand the short-term physiological response to these two tagging methods. Plasma cortisol, glucose, lactate, sodium, and potassium levels, as well as white muscle lactate and glycogen concentrations, were measured in samples obtained from fish upon capture (0 h) as well as 1 or 4 h after the tagging treatment. The effects of key biological variables, such as sex and proximity to spawn, on the physiological response to the tagging events were also evaluated. Tagging occurred during two distinct time periods representing fish of different maturation states and durations of freshwater residency. Overall, the physiological response to the tagging scenarios was characteristic of the disturbance associated with exhaustive exercise. There were no significant differences detected in the response profiles following gastric or external tagging procedures. This was despite procedural differences such as stomach perforations observed in 68% of the gastric insertions in the late sampling period, and external attachments taking three times longer (43 s) than gastric insertion (15 s). Moreover, the tagged fish showed similar response profiles to control fish that were handled but not tagged. These results suggest that the capture and handling associated with a tagging event induced physiological disturbance, and that the addition of a quick tagging procedure appeared to be nonadditive over the 4-h assessment period. Sex and proximity to spawn had significant main and interaction effects on some of the physiological response variables, indicating that biological context is important for interpreting physiological assessments in experiments that manipulate exercise and stress responses in migrating adult Pacific salmon.
... The unprecedented cold-weather experienced in the Gulf of Mexico in 2010 is one example of these extreme temperature events and resulted in a 12 • C and 6 • C drop in air and water temperatures, respectively, over a two week period leading to widespread mortality in fish populations [3]. Furthermore, variance in seasonal water temperatures that fishes experience within a given year can be quite large, ranging from below 5 • C to 19 • C for a cold water species such as rainbow trout, and 16 • C to 39 • C for zebrafish, a warm water species [4][5][6]. The poikilothermic nature of fish requires special consideration in the face of these challenges as changes in water temperature equate to changes in body temperature and can impact key physiological processes, such as the immune system and ultimately the health of the animal [7,8]. ...
As poikilothermic vertebrates, fish can experience changes in water temperature, and hence body temperature, as a result of seasonal changes, migration, or efflux of large quantities of effluent into a body of water. Temperature shifts outside of the optimal temperature range for an individual fish species can have negative impacts on the physiology of the animal, including the immune system. As a result, acute or chronic exposure to suboptimal temperatures can impair an organisms' ability to defend against pathogens and thus compromise the overall health of the animal. This review focuses on the advances made towards understanding the impacts of suboptimal temperature on the soluble and cellular mediators of the innate and adaptive immune systems of fishes. Although cold stress can result in varying effects in different fish species, acute and chronic suboptimal temperature exposure generally yield suppressive effects, particularly on adaptive immunity. Knowledge of the effects of environmental temperature on fish species is critical for both the optimal management of wild species and the best management practices for aquaculture species.
... Temperature has obvious implications on adaptive divergence in relation to cardiac performance and metabolism (Ineno, Tsuchida, Kanda, & Watabe, 2005;Perry, Danzmann, Ferguson, & Gibson, 2001;Taylor, 1991), and studies have found genetic bases for thermal tolerance in salmonids that reflects local adaptation (Eliason et al., 2011;Munoz, Farrell, Heath, & Neff, 2015;Narum et al., 2013). For instance, thermal-tolerant individuals can maintain higher heart rates and stroke volume in warmer temperatures, whereas thermal-intolerant individuals experience arrhythmia which affects metabolism and swimming performance (Ineno et al., 2005;Jain & Farrell, 2003). Therefore, temperature variables are expected to contribute to adaptive genetic variation. ...
Organisms typically show evidence of adaptation to features within their local environment. However, many species undergo long-distance dispersal or migration across larger geographical regions that consist of highly heterogeneous habitats. Therefore, selection may influence adaptive genetic variation associated with landscape features at residing sites and along migration routes in migratory species. We tested for genomic adaptation to landscape features at natal spawning sites and along migration paths to the ocean of anadromous steelhead trout (Oncorhynchus mykiss) in the Columbia River Basin. Results from multivariate ordination, gene-environment association, and outlier analyses using 24,526 single-nucleotide polymorphisms (SNPs) provided evidence that adaptive allele frequencies were more commonly associated with landscape features along migration paths than features at natal sites (91.8% versus 8.2% of adaptive loci, respectively). Among the 45 landscape variables tested, migration distance to the ocean and mean annual precipitation along migration paths were significantly associated with adaptive genetic variation in three distinct genetic groups. Additionally, variables such as minimum migration water temperature and mean migration slope were significant only in inland stocks of steelhead that migrate up to 1200 km farther than those near the coast, indicating regional differences in migratory selective pressures. This study provides novel approaches for investigating migratory corridors and some of the first evidence that environment along migration paths can lead to substantial divergent selection. Consequently, our approach to understand genetic adaptation to migration conditions can be applied to other migratory species when migration or dispersal paths are generally known. This article is protected by copyright. All rights reserved.
The parameters of the hyperbolic speed-duration relationship (the asymptote critical speed, CS, and the curvature constant, D') provide estimates of the maximal steady state speed (CS) and the distance an animal can run, swim, or fly at speeds above CS before it is forced to slow down or stop (D'). The speed-duration relationship has been directly studied in humans, horses, mice and rats. The technical difficulties with treadmill running in dogs and the relatively short greyhound race durations means that, perhaps surprisingly, it has not been assessed in dogs. The endurance capabilities of lizards, crabs and salamanders has also been measured, and the speed-duration relationship can be calculated from these data. These analyses show that 1) raising environmental temperature from 25 °C to 40 °C in lizards can double the CS with no change in D'; 2) that lungless salamanders have an extremely low critical speed due, most likely, to O2 diffusion limitations associated with cutaneous respiration; and 3) the painted ghost crab possesses the highest endurance parameter ratio (D'/CS) yet recorded (470 s), allowing it to maintain high speeds for extended periods. Although the speed-duration relationship has not been measured in fish, the sustainable swimming speed has been quantified in a range of species and is conceptually similar to the maximal steady state in humans. The high aerobic power of birds and low metabolic cost of transport during flight permits the extreme feats of endurance observed in bird migrations. However, the parameters of the avian speed-duration relationship have not been quantified.
Climate change stressors (e.g., warming and ocean acidification) are an imminent challenge to the physiological performance of marine organisms. Several studies spanning the last decade have reported widespread effects of warming and acidification on marine fishes, especially teleosts, but more work is needed to elucidate the responses in marine elasmobranchs, i.e., sharks and rays. Dispersal capacity, as a result of locomotor performance, is a crucial trait that will determine which group of elasmobranchs will be more or less vulnerable to changes in the environment. In fact, efficient and high locomotor performance may determine the capacity for elasmobranchs to relocate to a more favorable area. In this review we integrate findings from work on locomotion of marine sharks and rays to identify characteristics that outline potential vulnerabilities and strength of sharks and rays under climate change. Traits such as intraspecific variability in response to climatic stressors, wide geographic range, thermotaxis, fast swimming or low energetic costs of locomotion are likely to enhance the capacity to disperse. Future studies may focus on understanding the interacting effect of climatic stressors on morphology, biomechanics and energetics of steady and unsteady swimming, across ontogeny and species.
Several variables are involved in the patterns of distribution and spatio-temporal occupation of fish in a fluvial system. In this study, we evaluate numerous geographic (cascades, waterfalls and riffles) and physicochemical variables (slope, current velocity, pH, conductivity and dissolved oxygen) in different sections of the Quimán River, and its relationship with fish assemblage. This river is a mountain stream and presents an abrupt orography with various waterfalls, cascades and riffles that affect the connectivity of the river. Therefore, the working hypothesis was to establish if some of these geography and physicochemical variables can influence the spatial segregation of fish in the river. The results showed a significant variation (ANOSIM r = 0.6 p = 0.0006) in the composition of the assemblage along the river, defining a spatial segregation for native species, and a preferential habitat use was established by native species due to low current velocity environments (< 0.64 m s-1) and slope less than 3.5%. Nevertheless, a BEST/BIOENV analysis determined a low relationship between environmental variables and fish assemblage distribution (r = 0.37 p = 0.03). On the other hand, frequency of waterfalls, cascades and riffles decreased in the direction of the flow, in contrast to richness and diversity, even when there is a pisciculture and treatment plant of wastewater in the terminal section. It is suggested to develop more specific studies to understand the influence of geographic variables on native fish populations.
In commercial fish aquaculture, it is crucial to ensure that environmental rearing conditions are adequate, if not optimal, for fish growth, welfare and profitability. In recirculating aquaculture systems (RAS), where environmental conditions can be tightly controlled, targeting these optima may be important in offsetting high costs. However, truly optimal conditions for growth are rarely defined in the literature. In net-pen aquaculture, site selection permits some control over the most relevant parameters; however, it is clear that changes in environmental conditions, such as sub-optimal temperatures, hypoxia and algal blooms, are increasing in frequency and duration, often unpredictably. Thus, an understanding of how changes in relevant environmental parameters affect growth and physiological performance is vital for the selection of strains that may be more resistant to these and other unpredictable changes. In this chapter we provide a physiological framework based upon the “Fry paradigm” for defining optimal values of temperature, salinity and water velocity for fish growth and performance, and the impact of hypoxia and gill damage. We consider these parameters in isolation, but also in combination as they often co-vary in the culture environment. Furthermore, we promote the use of stress tolerance tests to predict the ability of fish to withstand changes in their environment that may arise due to unforeseen circumstances. Finally, we review the various assays that can be used to quantify physiological performance during changes in these environmental parameters.
Numerous laboratory and field studies have found that female Pacific salmon have higher mortality than males during their once-in-a-lifetime upriver spawning migration. However, the proximate cause(s) of this increased mortality are poorly understood. This study exposed sockeye salmon (Oncorhynchus nerka) to a mild capture and tagging stressor and evaluated physiological recovery and movement behaviour at 1 and 4 hours post-release. Female sockeye salmon did not expend more anaerobic energy in response to the stressor but did have higher plasma lactate levels 4 hours after the stressor, indicating that females took longer to physiologically recover compared to males. In addition, female salmon had lower plasma glucose but higher plasma cortisol, plasma K+, and cardiac lactate levels compared to males. Male and female salmon had markedly different post-release behaviours within the first hour of release; males were more likely to hold position within the staging area. Two potential mechanisms leading to increased mortality in female salmon were identified in this study: a) prolonged recovery duration (possibly mediated by elevated plasma cortisol levels) and b) insufficient oxygen delivery to the heart.
Aquaculture is increasingly being intensified, and the resulting higher stocking densities and feed inputs in closed systems can consequently lead to water quality fluctuations and/or deteriorations. Some of the most relevant water quality parameters in closed aquaculture systems include dissolved oxygen/redox potential, pH, salinity, temperature, and nitrogenous waste. These parameters should not deviate to extreme levels in order to minimize non-infectious diseases and subsequently ensure higher productivity in aquatic animals. Some husbandry strategies and novel systems to prevent or ameliorate deviations in these parameters will be discussed along with physiological responses in aquatic animals due to water quality induced non-infectious diseases. A final section will discuss the implications to noxious algae as a consequence of water quality deteriorations as well as feed spoilage/contamination along with mitigating strategies to ensure a better product for human consumers.
Previous results show that juvenile shortnose sturgeon are steady swimmers and, compared with salmonids, generally have low critical swimming (UCrit) and endurance swimming capacities. Most studies on swimming capacities of sturgeon, and other fishes, include those where fish have only been swum once and metrics of swimming performance are assessed (e.g., time swum, speed achieved). Under natural conditions, there are ample instances where fish would undergo multiple swimming cycles when traversing fish ways, culverts and other sources of fast water flow. While some evidence exists for salmonids, the effects of repeat swimming are not well known for sturgeon. The current study consisted of two experiments. The first examined the critical swimming (UCrit) of juvenile shortnose sturgeon following 3 consecutive swimming trials with a 30 minute recovery period between subsequent tests. The second examined the endurance swimming capacities of juvenile shortnose sturgeon following 3 consecutive swimming trials with a 60 minute recovery period between subsequent tests. Our findings indicate that: (i) UCrit was consistent (~2 Body lengths/s) among swimming trials; (ii) significant individual variation exists between individuals in the endurance swimming trials; and (iii) consistent results exist for individuals across swimming trials in both the UCrit and the endurance swimming tests. These results suggest that juvenile shortnose sturgeon have a high recovery capacity, and their behaviour and morphology likely reflect aspects of their swimming capacities. This article is protected by copyright. All rights reserved.
An open channel flume was used to characterize the swimming performance of Rainbow Trout Oncorhynchus mykiss and Westslope Cutthroat Trout O. clarki lewisi ranging nominally in fork length from 15 cm to 30 cm. To achieve this, an open-channel flume was used to observe volitional swim performance of wild-caught Rainbow Trout and Westslope Cutthroat Trout - the fish were not coerced, prodded or spooked into action. The maximum short-duration swim speed of the fish was also observed, providing important effective leap or velocity challenge information for the design of intentional barriers. The experiment was conducted with a consistently low water velocity challenge. Swim speeds were characterized using weighted least squares regression, revealing no evidence of a difference in swim speeds between the two species. The overall average swim speed for Rainbow Trout was estimated to be 0.84 m/s (SE = 0.02) with a 95% confidence interval of (0.79, 0.89) m/s, and that for the Westslope Cutthroat Trout was estimated to be 0.84 m/s (SE = 0.03) with a 95% confidence interval of (0.78, 0.90) m/s. The maximum swim speeds observed were 2.72 m/s for Rainbow Trout and 3.55 m/s for Westslope Cutthroat Trout. The project results provide new information on the swimming ability of wild trout that can be used to improve fish passage or barrier design.
A skin fibroblast cell line WE-skin11f from walleye (Sander vitreus) was used to study the impact of temperature (26 °C, 20 °C, 14 °C, or 4 °C) on the transcript levels of genes involved in the endogenous antigen processing and presentation pathway (EAPP), which is an important antiviral pathway of vertebrates. Partial coding sequences were found for 4 previously unidentified walleye EAPP members, calreticulin, calnexin, erp57, and tapasin, and the constitutive transcript levels of these genes in WE-skin11f was unchanged by culture incubation temperature. The viral mimic poly (I:C) and viral haemorrhagic septicaemia virus (VHSV) IVb were used to study possible induction of EAPP transcripts (b2m, mhIa, and tapasin). The walleye cells were exquisitely sensitive to poly (I:C), losing adherence and viability at concentrations greater than 100 ng/mL, particularly at suboptimal temperatures. VHSV IVb viral particles were produced from infected WE-skin11f cells at 20 °C, 14 °C, and 4 °C but with much lower production at 4 °C. Under conditions where their impact on the viability of WE-skin11f cultures was slight, poly (I:C) and VHSV IVb were shown to induce b2m, mhIa, and tapasin transcriptºs at 26 °C and 20 °C respectively. However, at 4 °C, the up-regulation of EAPP transcript levels was either delayed or completely impaired when compared to the 26 °C and 20 °C control temperatures of the respective experiments. These in vitro results suggest that suboptimal temperatures may be capable of modulating the regulation of the EAPP in walleye cells during viral infection.
Organisms that live in coastal estuaries often experience significant seasonal and annual fluctuations in salinity that they must either endure or move to avoid. Largemouth Bass Micropterus salmoides is a freshwater fish that lives in coastal estuaries and does not migrate/move to avoid seasonal salinity increases. Additionally, estuarine Largemouth Bass exhibit growth rates, condition factors, and life history strategies that differ from their inland counterparts. These differences suggest the potential for physiological adaptations to tolerate and even thrive in estuarine environments. We compared swimming performance (quantified as critical swimming speed, Ucrit) of Largemouth Bass (280–404 mm total length) from an Alabama estuarine population versus an inland population at 0, 4, 8, and 12 ppt salinities to test for physiological performance-based adaptation to tolerate elevated salinities. Ucrit values did not differ between inland and estuarine Largemouth Bass nor were there any salinity effects. Although inland and estuarine Largemouth Bass may possess different physiological mechanisms for tolerating salinity, those mechanisms did not affect swimming performance.
We used a swimming respirometer to measure oxygen consumption (i. e., metabolic cost) of four species of stream fishes while they held position at diferent velocities. We tested naturally acclimatized individuals during spring, summer, fall, and winter at seasonal temperatures and photoperiods. Rosyside dace (Clinostomus funduloides), longnose dace (Rhinichthys cataractae), mottled sculpin (Cottus bairdi), and juvenile rainbow trout (Oncorhynchus mykiss) all showed seasonal changes in oxygen consumption. Seasonal changes in standard metabolic rates seemed to be influenced by changes in reproductive condition as well as ambient temperature. The metabolic cost of maintaining position for rainbow trout and rosyside dace generally increased with velocity. At velocities below eight body lengths per second, longnose dace did not exhibit a significant change in oxygen consumption, because they held position without swimming. At higher velocities, however, long-nose dace swam to maintain their position and oxygen consumption increased rapidly. Mottled sculpin held position without swimming and therefore showed little or no change in energy use with changing current velocity.
Atlantic salmon Salmo salar, returning to freshwater to spawn, were angled and then terminally sampled to test the hypothesis that angling during warmer summer months (water temperatures of 20 ± 2°C) increases the magnitude of physiological disturbances in the white muscle. Angling immediately reduced white muscle ATP and phosphocreatine stores, but these high-energy phosphates were replenished within 2–4 h. Intramuscular glycogen stores were nearly depleted after angling, but unlike the response by salmon angled in the fall at 6°C, there was no glycogen resynthesis during the 4-h recovery period. Marked increases in white muscle lactate and the postexercise metabolic proton load (H+m ) accompanied glycogen depletion. The time course of lactate elimination and H+m correction, however, was much slower than previously observed in fall-angled salmon. Finally, considerable delayed postangling mortality (40%) was observed in a subgroup of Atlantic salmon that were angled at 22°C. We conclude that angling in warm summer water impairs restorative processes and increases the susceptibility of Atlantic salmon to delayed postangling mortality. We suggest that anglers can mitigate the magnitude of angling-induced physiological disturbances in Atlantic salmon during midsummer by minimizing playing time and postangling air exposure.
Summary Haematological variables were measured during aerobic swimming (45-55 % of L^u) and at critical swimming velocity (£/Crit) in acutely splenectomized and sham- operated rainbow trout. There was no correlation between haematocrit (Hct) and £/crjt in either group of fish. The control values for the haematological variables did not differ significantly between the two groups of fish. Some haematological variables changed during aerobic swimming and at t/crit, but there were no significant differences between the two groups for any of the variables. Arterial blood oxygen tension was significantly reduced at £/crjt. Arterial blood oxygen content (Cao2) was maintained in sham-operated fish because the Hct increased significantly. However, in the splenectomized animals, Cao, decreased (compared to control values) during aerobic swimming and at t/crit because the Hct did not change. Plasma concentrations of lactate and catecholamines were elevated only at Ucril. We provide evidence of a graded spleen contraction during aerobic swimming.
Blood flow in the intestinal artery (qIA), the rate of oxygen consumption and a number of haematological variables were measured in chinook salmon, Oncorhynchus tshawytscha, while they swam up to the critical swimming velocity (Ucrit). The fish used in this study had previously been exposed to one of two different exercise-training regimes, swimming for 8 months at either 1.5bl s−1 (HS) or 0.5bl s−1 (LS) (where bl is body length). During this period, growth rate was the same in both groups.
At rest, qIA was approximately 36% of cardiac output. qIA was inversely related to , indicating that blood flow was gradually redistributed from the viscera as the oxygen demands of the locomotory muscles increased. Both and qIA were relatively constant at swimming velocities less than 50% Ucrit, but at Ucrit, qIA had decreased by 60–70% as reached a maximum. Blood flow redistribution away from the intestine contributed significantly to the oxygen supply for locomotory muscles, since it was estimated that the oxygen-transporting capacity of this redistributed blood flow was enough to support 12–18% of the maximum internal oxygen consumption (total – gill ).
Following exercise training, haematocrit (Hct) in the HS group (27.1%) was significantly higher than in the LS group (23.3%). However, neither the maximum nor Ucrit was significantly different in the two groups. qIA was inversely related to Hct but, in spite of lower qIA at rest, oxygen transport to the intestines was greater at all swimming speeds in the HS than in the LS training group. In addition, blood flow in the HS group was better maintained as the swimming speed was increased. As a result of the higher Hct in the HS-trained group, oxygen transport to the intestines was similar in both groups at their respective training velocities. Therefore, we suggest that, by increasing Hct and thereby maintaining oxygen delivery to the intestines, the HS group maintained normal intestinal function while swimming at the higher velocity, enabling overall growth rate to be the same as in the LS group.
The effect of intermittent severe exercise of short duration on carbohydrate metabolism was examined using unanesthetized, intact rainbow trout. The levels of muscle glycogen, muscle lactate, blood lactate, and liver glycogen were determined in fish sampled immediately after severe exercise of 3 sec to 5 min, after recovery of 3 min to 60 min, and after re-exercise of 3 sec to 5 min. It appears that rainbow trout are not well adapted to tolerate frequent exercise of short duration.
Voltage-clamp studies on intact and internally perfused squid giant axons demonstrate that ammonium can substitute partially for either sodium or potassium. Ammonium carries the early transient current with 0.3 times the permeability of sodium and it carries the delayed current with 0.3 times the potassium permeability. The conductance changes observed in voltage clamp show approximately the same time course in ammonium solutions as in the normal physiological solutions. These ammonium ion permeabilities account for the known effects of ammonium on nerve excitability. Experiments with the drugs tetrodotoxin (TTX) and tetraethyl ammonium chloride (TEA) demonstrate that these molecules block the early and late components of the current selectively, even when both components are carried by the same ion, ammonium.
Adult brown trout were acclimated for 2–4 weeks to artificial, soft water (Ca2+ 25μmol l-1) at neutral pH and at summer (15°C) or winter (5°C) temperatures. During this period they swam against a current of approximately 0.25 ms-1. They were then exposed to neutral or sublethal pH for 4 days in still water. For fish with their dorsal aorta catheterized, sublethal pH was 4 at 5°C and 4.5 at 15°C.
After 4 days of exposure to sublethal pH, resting oxygen uptake was 40 % higher than that at neutral pH for fish held at 15 °C and 38 % higher for fish held at 5°C. Critical swimming speeds (Ucrit), in contrast, were 35% and 31% lower, respectively. These two phenomena may be related in as much as the ‘metabolic cost’ of exposure to low pH may increase as swimming speed increases, thus reducing the scope for activity. Another important factor could be an impairment of oxygen delivery to the red muscle fibres. Although arterial O2 concentrations and heart rate are both similar for fish at Ucrit in neutral and acid water, there are signs of haemoconcentration in fish exposed to low pH, and the consequent increase in blood viscosity could disrupt the local circulation in the red fibres. Whatever its causes, an impairment of swimming activity resulting from exposure to acid water may have severe consequences for active fish such as salmonids.
Exposure to sublethal pH caused significant reductions in plasma Na+ and Cl-concentrations at both temperatures, although these were more substantial at 5°C than at 15 °C. Swimming at Ucrit had no significant effect on plasma concentrations of Na+, K+ and Cl- except at sublethal pH at 5°C, when there were significant reductions in all three.
Seasonal temperature had significant but small effects on resting and Ucrit, and these are discussed in terms of the possible effects of low temperature and continued swimming activity (training) on hypertrophy of skeletal and cardiac muscles and on the aerobic capacity of the ‘red’ muscle fibres.
Chronically cannulated rainbow trout were subjected to 6 min of severe burst exercise and monitored over a 12 h recovery period. There were short-lived increases in haematocrit, haemoglobin, plasma protein, Na+ and Cl− levels. Plasma [Cl−] later declined below normal as organic anions accumulated. A much larger and more prolonged elevation in plasma [K+] probably resulted from intracellular acidosis. An intense extracellular acidosis was initially of equal respiratory (i.e. ) and metabolic (i.e. ) origin. However was rapidly corrected while the metabolic component persisted. Plasma ammonia increases had negligible influence on acid-base status. Elevations in blood lactate (ΔLa−) were equal to immediately post-exercise but later rose to twice the latter. Simultaneous white muscle biopsies and blood samples demonstrated that muscle to blood gradients of lactate and pyruvate were maximal immediately post-exercise. As blood levels rose and muscle levels declined, an approximate equilibrium was reached after 4 h of recovery. Intra-arterial infusions of lactic acid in resting trout produced a severe but rapidly corrected metabolic acidosis. The rates of disappearance of and ΔLa− from the blood were equal. Infusions of similar amounts of sodium lactate produced a small, prolonged metabolic alkalosis with a much slower ΔLa− disappearance rate. It is suggested that the excess of ΔLa− over in the blood after exercise is associated with differential release rates of the two species from white muscle rather than differential removal rates from the bloodstream, and that the majority of the lactic acid load in muscle is removed by metabolism in situ.
This chapter describes the biochemical events involved in the transition from a resting to an actively swimming condition. The chapter deals with metabolism in myotomal muscle, but there are other organs, integrally important for the maintenance of homeostasis, that may be extremely expensive to operate during sustained swimming. For instance, the cost of osmoregulation, in freshwater, for actively swimming rainbow trout (Salmo gairdneri), may be as high as 30% of the total metabolism of the fish. Much of this energy expenditure must be borne by the gills. The cost of maintaining the cardiac pump may also be quite substantial. In fact, at high oxygen consumption rates, this may approach 15% of the total metabolism of the animal. Thus, the myotomal muscle per se may account for only about 50% of the total energy output. In light of this, it is somewhat surprising that tissues other than skeletal muscle are rarely studied by fish physiologists interested in metabolic alterations during swimming. The chapter describes the control of metabolism in these support tissues and skeletal muscle; however, the understanding of metabolism in fish tissues is at best fragmentary. Hence, where appropriate, the better-studied mammalian systems are called upon to complement and supplement the discussion.
The relationship between temperature and the role of the gill in acid-base regulation was investigated in rainbow trout acclimated to 5° or 18° C. At rest and following exhaustive exercise, trout acclimated to warmer temperatures had greater net losses of both ammonia and basic equivalents to the environmental water than cold-acclimated fish. In contrast, there were no significant effects of temperature on the net fluxes of acid equivalents, Na⁺, or Cl⁻ at rest. Following exercise, however, the net excretion of acid equivalents was about 1.5 times greater in fish acclimated to 18° C than in fish acclimated to 5°C. In addition, net fluxes of both Na⁺ and Cl⁻ to the environmental water after exercise were greater in warm-acclimated fish. In a second series of experiments, the time courses for the clearance of infused acid loads (lactic acid and ammonium sulfate) from the blood space were compared in trout acclimated to either 5° or 18° C. Since the clearance of the metabolic proton load from the blood was not influenced by temperature under these conditions, it appears that the different rates of metabolic proton excretion after exercise at different temperatures may result largely from the effects of temperature on the movement of protons from the muscle to the blood. A compartmental analysis of the whole body acid load following exercise showed that the gills played only a small role in the overall correction of a blood acid-base disturbance in trout, regardless of thermal history. However, the quantity of metabolic protons removed from the blood across the gills to the environmental water was generally equivalent to the blood metabolic proton concentration. Temperature may therefore have an important effect on the recovery of the acid-base disturbance in the blood (extra cellular fluid) via branchial proton excretion. Temperature had its greatest influence on clearance of metabolic protons from the white muscle during the first 4 h after exercise.
The effects of cortisol on metabolic recovery from exhaustive exercise in rainbow trout (Oncorhynchus mykiss) and potential mechanisms of action were investigated. When the postexercise rise in cortisol is prevented in fish by blocking either cortisol synthesis with metyrapone or cortisol release with dexamethasone, there is a faster recovery of blood and muscle metabolites and acid-base status in those fish than in control fish. To investigate whether preventing the rise in plasma cortisol is responsible for these effects, two experiments were done. Cortisol infused intofish treated with metyrapone returned the rate of recovery to that of control fish. Treatment with 11-deoxycortisol or deoxycorticosterone, intermediates in the cortisol biosynthetic pathway, the levels of which are possibly increased by metyrapone treatment, did not increase the rate of recovery; indeed, plasma cortisol was elevated and recovery prolonged in fish treated with 11-deoxycortisol. These experiments indicate that preventing the postexercise rise in plasma cortisol is associated with decreasing the time required for metabolic and acid-base recovery. The mechanism of cortisol action is not alteration of net acid excretion at the gills or mediated by some action at the RU486-sensitive cortisol receptor. It is suggested that cortisol may play an adaptive role in recovery from exhaustive exercise by providing lactate as a postexercise aerobic fuel.
This paper describes the design of a modified Brett-type respirometer for use with fish up to 2 kg at swimming speeds as high as 2.5 m·s(-1). Control of the respirometer, experimental monitoring and data acquisition are performed by computer. Water velocity, temperature, pH, dissolved oxygen and carbon dioxide can be controlled at predetermined levels to enable experiments to be conducted over several days with minimal deterioration in water quality.
The effect of oleate, palmitate, and octanoate on glucose formation was studied with lactate or pyruvate as substrate. Octanoate was much more quickly oxidized and utilized for ketone body production than were oleate and palmitate. Among fatty acids studied, only octanoate resulted in a marked increase of the 3-hydroxybutyrate/acetoacetate (3-) ratio. Each of the fatty acids studied stimulated glucose synthesis from pyruvate. The enhancement of gluconeogenesis by long-chain fatty acids was abolished after the addition of ammonia. As concluded from the “crossover” plot, the stimulatory effect of fatty acids was due to: (i) a stimulation of pyruvate carboxylation, (ii) a provision of reducing equivalents for glyceraldehyde phosphate dehydrogenase, and (iii) an acceleration of flux through hexose diphosphatase. Moreover, palmitate and oleate resulted in an increased generation of mitochondrial phosphpenolpyruvate, while in the presence of octanoate, the activity of mitochondrial phosphoenolpyruvate carboxykinase was diminished. When lactate was used as the glucose precursor, palmitate and oleate increased glucose production by about 50% but did not affect the contribution of mitochondrial phosphoenolpyruvate carboxykinase to gluconeogenesis. In contrast, in spite of the stimulation of both pyruvate carboxylase and hexose diphosphatase, as judged from the crossover plot, the addition of octanoate resulted in a marked inhibition of both glucose formation and mitochondrial generation of phosphoenolpyruvate. The inhibitory effect of octanoate was reversed by ammonia. Results indicate that fatty acids and ammonia are potent regulatory factors of both the rate of glucose formation and the contribution of mitochondrial phosphoenolpyruvate carboxykinase to gluconeogenesis in hepatocytes of the fasted rabbit.
To reduce mortality in the by-catch of commercial salmon fisheries, techniques are being explored to revive fish before live release and improve survival. By measuring blood and muscle variables, we demonstrated that capture of coho salmon (Oncorhynchus kisutch) by commercial trolling methods resulted in severe exhaustion and stress, e.g., muscle lactate reached 46.1 mmol·kg-1 while muscle phosphocreatine (PCr) decreased to 6.1 mmol·kg-1. Nevertheless, coho salmon recovered rapidly by swimming in a cage alongside the vessel while fishing activity continued. In particu- lar, there were significant increases in muscle glycogen and PCr levels, and a decrease in muscle lactate after two hours. Notably, and in contrast to when exhausted fish are held stationary during recovery, plasma lactate remained low (
Critical swimming speed was measured for largemouth bass and found to be related to the increments of both time and water velocity. Critical speed decreased with increase in time interval, and reached a peak and declined thereafter with increasing velocity increment.
SYNOPSIS. Studies on the relation of temperature to tolerance, preference, metabolic rate, performance, circulation, and growth of sockeye salmon all point to a physiological optimum in the region of 15°C. Natural occurrence is limited in time and space at temperatures above 18°C despite being able to tolerate 24°C. Forms of physiological inadequacy can be demonstrated which account for such restrictions in distribution. Predictive power for locating and accounting for concentrations of young fish in thermally stratified lakes appeared to provide "proof" for the controlling influence of the physiological optimum temperature. Early literature on the ecology of sockeye supported this view. Recent studies using midwater trawls and sonar detection reveal a diurnal behavior pattern which points to a more subtle interaction of biotic andabiotic factors governing vertical distribution in which the controlling force appears to be bioenergetic efficiency. It is concluded that a mechanism of behavioral thermoregulation has evolved which favorably balances daily metabolic expenditures in order to conserve energy when food is limited.
Burst swimming in fish results in a marked metabolic acidosis. Chinook salmon (Oncorhynchus tshawytscha) blood was shown to have a marked Root shift, such that burst swimming and the subsequent metabolic acidosis should impair oxygen delivery to the tissues and, therefore, aerobic swimming capacity. Burst swimming was found to have no effect on aerobic swimming capacity in Chinook salmon and it is concluded that any effects on aerobic swimming, of the induced metabolic acidosis following burst swimming, was offset by the release of catecholamines.
1.1. Studies of purified 6-phosphofructo-1-kinase (PFK) from white skeletal muscle of the rainbow trout (Oncorhynchus my kiss) were undertaken to illuminate aspects of the regulation of glycolysis in muscle under resting versus exercising conditions.2.2. Trout muscle PFK was strongly inhibited by ATP at physiological levels and was regulated by a number of allosteric effectors.3.3. Allosteric activators included ammonium ion, inorganic phosphate, AMP, ADP, and fructose-2,6-bisphosphate (F2.6P2); these enhanced enzyme affinity for F6P and reversed inhibition by ATP.4.4. Changes in pH also played a major role in PFK regulation; as pH decreased from 7.2 to 6.6 (mimicking the pH decrease during exhaustive exercise), not only was enzyme activity reduced, but the reaction cooperativity increased as well.5.5. The negative effect of reduced pH, however, was fully compensated for by the rise in the levels of positive modulators, such AMP following exercise.6.6. When assayed under substrate and effector concentrations that reflected “resting” vs “exercised” situations in muscle, the S0.5 values for F6P were reduced by 50- and 123-fold, respectively, to values of 0.068 and 0.15 mM, both close to the physiological levels of F6P.
The effects of catch and release angling on muscle physiology, survival and gamete viability were examined in wild Atlantic salmon (Salmo salar), just prior to spawning. Lactate in the white muscle increased to 37.4 mu mol . g(-1) after angling and recovered within 4 h. Muscle pH decreased from 7.46 at rest to 6.80 following angling, but returned to resting levels within 2 h. White muscle concentrations of PCr, ATP, and glycogen were depleted by 74, 46, and 73%, respectively, following angling. ATP and PCr returned to resting levels within 2 h, but glycogen did not recover until 12 h. The absence of significant changes in blood glucose indicated that the stress response was minimal in salmon angled under these conditions (6 degrees C). There were also no mortalities among 20 salmon that were angled and transported to the hatchery. Multi-sea-winter (MSW) salmon (> 63 cm) required a longer period to angle to exhaustion than grilse (< 63 cm), but the physiological disturbance was less in MSW salmon. The survival of eggs from angled and nonangled salmon was 98 and 97%, respectively. Together, these results support the strategy of a late-season catch and release fishery for Atlantic salmon.
Exercise to exhaustion, as indicated by near depletion of muscle glycogen stores, resulted in a 2- to 3-fold increase in the levels of plasma cortisol, but there was no consistent effect of exercise on plasma insulin, glucagon, T3 or T4 levels. Treatment of rainbow trout (Oncorhynchus mykiss) with metyrapone (which inhibits cortisol synthesis) 1 h or dexamethasone (which inhibits cortisol release) 24 h prior to exercise successfully blocked the exercise-induced rise in plasma cortisol. Neither metyrapone nor dexamethasone treatment had any effect on exercise performance, as muscle glycogen was depleted and lactate accumulated to the same extent in control and treated fish. Control fish showed the typical blood lactate response to exhaustive exercise: [lactate] peaked at 10–15 μmol∙mL−1 about 2–4 h post exercise and returned to pre-exercise levels within 8 h. The response of blood lactate in cortisol-blocked fish was significantly different: post-exercise levels were rarely greater than 5 μmol∙mL−1 and had returned to resting levels by 2 h. Analysis of tissue metabolite and acid–base status indicated that cortisol-blocked fish recovered faster than did controls. In treated fish, muscle glycogen and lactate levels had returned to pre-exercise levels within 2 h. Blood pH and muscle intracellular pH were also restored to pre-exercise values within 2 h. In contrast, restoration of tissue metabolite and acid–base status in control fish required up to 8 h. The fact that both metyrapone and dexamethasone treatment had the same effects on recovery metabolism suggests that it is the absence of the rise in plasma cortisol, rather than the drug treatment itself, which is responsible for the enhancement of metabolic recovery.
Glycogen depletion was used as an experimental tool to examine the relationship between excess post-exercise oxygen consumption and lactate metabolism in 6-g rainbow trout. A 5-day starvation period reduced whole-body glycogen stores by 50% and slightly lowered resting lactate levels; resting oxygen consumption, glucose, ATP, and creatine phosphate levels were not affected. After a 5-min bout of exhaustive exercise, significantly less glycogen was utilized by the glycogen-depleted fish, 40% less lactate was accumulated, and glucose levels did not rise in comparison with the control group. Creatine phosphate recovered more quickly in the glycogen-depleted fish, whereas ATP was unaffected. Recovery from excess post-exercise oxygen consumption was not significantly different despite the large absolute differences in lactate removed and glycogen resynthesized. This experimental test demonstrates that the classical oxygen debt hypothesis does not completely explain the excess post-exercise oxygen consumption in the trout.
The modal preferred temperatures of rainbow trout acclimated to 5 °C, 10 °C, 15 °C., and 20 °C. were determined photographically to be 16 °C, 15 °C., 13 °C, and 11 °C., respectively. The final preferendum was 13 °C. The phenomenon of decreasing preferred temperature with increasing acclimation temperature has not been reported for any other species of fish.
The critical swimming velocity (U-crit) and haematology of wild and hatchery-reared coho salmon (Oncorhynchus kisutch) juveniles were examined in either fresh water or seawater following a 24-h seawater challenge, at the time of smoltification. In fresh water, wild smelts swam faster than hatchery-reared fish but this could largely be accounted for by scaling for body size. Transfer to seawater significantly elevated resting plasma [Na+] and reduced subsequent U-crit in hatchery fish (by 12%) relative to that determined in fresh water but had no significant effect on resting plasma [Na+] and U-crit in wild fish. Swimming the fish a second time in seawater after the initial 2-h exercise period resulted in a significant reduction in U-crit relative to that in fresh water in both wild fish (16%) and hatchery fish (a further 14%); this relatively greater impairment in U-crit in hatchery fish was due to a reduced hypo-osmoregulatory ability following seawater transfer that impairs conditions for muscle contractility and aerobic metabolism. Aerobic metabolism in seawater-exposed fish was affected in part through a reduction in haematocrit and an increase in plasma volume, reducing oxygen carrying capacity of the blood relative to conditions in fresh water.
Measurements of swimming ability, such as critical swimming speed (Ucrit), have commonly been used as indicators of the effects of environmental challenges on the general health of fish. In this study, we introduce repeat swimming performance as a particularly sensitive means to assess fish health and the effects of environmental stressors. Adult sockeye salmon (Oncorhynchus nerka) performed two Ucrit tests separated by a 40-min recovery period. When recovery ability was expressed as a ratio of Ucrit values in the first and second swim challenges (Ucrit,2/Ucrit,1), control fish exhibited recovery ratios of unity (0.98 ± 0.01 (mean ± SEM)). In contrast, the recovery of fish pre-exposed to between 0.12 and 0.77 mg·L-1 dehydroabietic acid (DHA) for 8-14 h, and swimming in either hypoxia or normoxia, was impaired. These fish had recovery ratios significantly lower than unity (0.92 ± 0.02) despite swimming to a similar initial Ucrit as control fish. The effect of pre-exposure to DHA was also evident in measurements of oxygen consumption and plasma lactate concentration. Unhealthy fish exhibited significantly lower initial and second Ucrit values than control fish. To account for the low initial swimming performance of these fish, a normalized recovery ratio was introduced ((Ucrit,1/Ucrit,1(control) + Ucrit,2/Ucrit,1)/2). This index of recovery (0.65 ± 0.08) identified the poor physical status of these fish.
Adult brown trout were acclimated for 2–4 weeks to artificial soft water ([Ca2+] 25 μmol l−1) at neutral pH and at summer (15°C) temperature. During this period they swam against a current of approximately 0.25 ms −1. They then had their dorsal aorta cannulated and were exposed to neutral or sublethal pH (4.5) for 4 days in still water.
After 4 days of exposure to sublethal pH, critical swimming speed (Ucrit) was 35% lower than that for fish at neutral pH. There were significant increases in arterial and in blood lactate concentrations at Ucrit compared with the values in resting fish at neutral pH and these led to significant reductions in plasma pH. There were no such changes in fish at sublethal pH. There were no significant changes in intracellular pH (pHi) of red blood cells at Ucrit, probably as a result of increases in the levels of plasma catecholamines. There were significant reductions in pHi of red and white muscle fibres at Ucrit. It is argued that these values were not as low in the white fibres as those seen in previous studies after fish have been chased to exhaustion and, therefore, that the fish in the present study were not completely exhausted, although they would no longer swim at a steady speed. As pHi of the red muscle was the same at Ucrit for fish at neutral and at sublethal pH, it is suggested that Ucrit (fatigue) coincides with a particular pHi of the red muscles and possible mechanisms are discussed.
Atlantic salmon (Salmo salar) were acclimated and exhaustively exercised at 12, 18, or 23°C to determine how temperature influences the magnitude of postexercise physiological disturbances. At each temperature, exercise led to decreased white muscle ATP and phosphocreatine concentrations. Phosphocreatine was rapidly restored within 1 h at each temperature whereas ATP restoration took 1-4 h at 18 and 23°C, but considerably longer at 12°C. Exercise-induced depletions of white muscle glycogen were accompanied by elevations in muscle lactate, which contributed to 0.6 unit decreases in white muscle intracellular pH (pHi) at each temperature. Compared with rates of recovery in warmer water, glycogen resynthesis, lactate catabolism, and pHi correction were slower at 12°C. White muscle REDOX state estimates suggested that slower postexercise recovery at 12°C was not due to oxygen delivery limitations. Marked postexercise elevations in plasma osmolality and lactate concentration were also observed and in each case correction of the disturbance took longer at 12°C. Paradoxically, significant mortality (30%) was observed only at 23°C. We conclude that while warmer water facilitates postexercise recovery of white muscle metabolic and acid-base status in Atlantic salmon, extremely high temperatures may make them more vulnerable to delayed postexercise mortality.