Repeatability of standard metabolic rate, active metabolic rate and aerobic scope in young brown trout during a period of moderate food availability

Zoophysiology, Department of Biological Sciences, Aarhus University, DK-8000 Aarhus C, Denmark.
Journal of Experimental Biology (Impact Factor: 2.9). 05/2011; 214(Pt 10):1668-75. DOI: 10.1242/jeb.054205
Source: PubMed


Standard metabolic rate (SMR) and active metabolic rate (AMR) are two fundamental physiological parameters providing the floor and ceiling in aerobic energy metabolism. The total amount of energy available within these two parameters confines constitutes the absolute aerobic scope (AAS). Previous studies on fish have found SMR to closely correlate with dominance and position in the social hierarchy, and to be highly repeatable over time when fish were provided an ad libitum diet. In this study we tested the temporal repeatability of individual SMR, AMR and AAS, as well as repeatability of body mass, in young brown trout (Salmo trutta L.) fed a moderately restricted diet (0.5-0.7% fish mass day⁻¹). Metabolism was estimated from measurements of oxygen consumption rate (M(.)(O₂)) and repeatability was evaluated four times across a 15-week period. Individual body mass was highly repeatable across the entire 15 week experimental period whereas residual body-mass-corrected SMR, AMR and AAS showed a gradual loss of repeatability over time. Individual residual SMR, AMR and AAS were significantly repeatable in the short term (5 weeks), gradually declined across the medium term (10 weeks) and completely disappeared in the long term (15 weeks). We suggest that this gradual decline in repeatability was due to the slightly restricted feeding regime. This is discussed in the context of phenotypic plasticity, natural selection and ecology.

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Available from: Tommy Norin, Jul 06, 2015
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    • "microbial respiration) followed Rosewarne et al. (2015). Maximal metabolic rate (MMR) was elicited using the chase protocol described previously (Cutts et al., 2002; Norin and Malte, 2011; Svendsen et al., 2014). Individual fish were transferred to a circular trough and chased manually until exhaustion as evidenced by the fish not reacting to being turned upside down and lifted partly out of the water. "
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    ABSTRACT: Ongoing climate change is affecting animal physiology in many parts of the world. Using metabolism, the oxygen- and capacitylimitation of thermal tolerance (OCLTT) hypothesis provides a tool to predict the responses of ectothermic animals to variation in temperature, oxygen availability and pH in the aquatic environment. The hypothesis remains controversial, however, and has been questioned in several studies. A positive relationship between aerobic metabolic scope and animal activity would be consistent with the OCLTT but has rarely been tested. Moreover, the performance model and the allocation model predict positive and negative relationships, respectively, between standard metabolic rate and activity. Finally, animal activity could be affected by individual morphology because of covariation with cost of transport. Therefore, we hypothesized that individual variation in activity is correlated with variation in metabolism and morphology. To test this prediction, we captured 23 wild European perch (Perca fluviatilis) in a lake, tagged them with telemetry transmitters, measured standard and maximal metabolic rates, aerobic metabolic scope and fineness ratio and returned the fish to the lake to quantify individual in situ activity levels. Metabolic rates were measured using intermittent flow respirometry, whereas the activity assay involved high-resolution telemetry providing positions every 30 s over 12 days. We found no correlation between individual metabolic traits and activity, whereas individual fineness ratio correlated with activity. Independent of body length, and consistent with physics theory, slender fish maintained faster mean and maximal swimming speeds, but this variation did not result in a larger area (in square metres) explored per 24 h. Testing assumptions and predictions of recent conceptual models, our study indicates that individual metabolism is not a strong determinant of animal activity, in contrast to individual morphology, which is correlated with in situ activity patterns.
    Full-text · Article · Jan 2016 · Conservation Physiology
    • "The risk of underestimating SMR decreases, of course, as the number of ˙ MO 2 values used to estimate SMR increases. This number is highly variable among studies, e.g. one (Wieser & Medgyesy, 1991), three (Crear & Forteath, 2000;McKenzie, 2001;Roche et al., 2013), five (Lefevre et al., 2012), six (Neto & Steffensen, 1997;Schurmann & Steffensen, 1997) or 10 (Norin & Malte, 2011;Boldsen et al., 2013;Svendsen et al., 2014). Recognizing the potential for aberrant low ˙ MO 2 values, others have used 10% of the values (Herrmann & Enders, 2000;Rosewarne et al., 2014), or all ˙ MO 2 values obtained during the quiet part of the daily cycle (Castanheira et al., 2011), or after a specific time since the beginning of the experiment (Cutts et al., 2002). "
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    ABSTRACT: This review and data analysis outline how fish biologists should most reliably estimate the minimal amount of oxygen needed by a fish to support its aerobic metabolic rate (termed standard metabolic rate; SMR). By reviewing key literature, it explains the theory, terminology and challenges underlying SMR measurements in fishes, which are almost always made using respirometry (which measures oxygen uptake, ṀO2). Then, the practical difficulties of measuring SMR when activity of the fish is not quantitatively evaluated are comprehensively explored using 85 examples of ṀO2 data from different fishes and one crustacean, an analysis that goes well beyond any previous attempt. The main objective was to compare eight methods to estimate SMR. The methods were: average of the lowest 10 values (low10) and average of the 10% lowest ṀO2 values, after removing the five lowest ones as outliers (low10%), mean of the lowest normal distribution (MLND) and quantiles that assign from 10 to 30% of the data below SMR (q0·1, q0·15, q0·2, q0·25 and q0·3). The eight methods yielded significantly different SMR estimates, as expected. While the differences were small when the variability was low amongst the ṀO2 values, they were important (>20%) for several cases. The degree of agreement between the methods was related to the c.v. of the observations that were classified into the lowest normal distribution, the c.v. MLND (C.V.MLND). When this indicator was low (≤5·4), it was advantageous to use the MLND, otherwise, one of the q0·2 or q0·25 should be used. The second objective was to assess if the data recorded during the initial recovery period in the respirometer should be included or excluded, and the recommendation is to exclude them. The final objective was to determine the minimal duration of experiments aiming to estimate SMR. The results show that 12 h is insufficient but 24 h is adequate. A list of basic recommendations for practitioners who use respirometry to measure SMR in fishes is provided.
    No preview · Article · Jan 2016 · Journal of Fish Biology
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    • "There are fewer data available on interindividual variation in MMR, but the magnitude of the variation appears to be similar (Norin & Malte, 2011Killen et al., 2012;Metcalfe, N. B. et al., 2016;Norin et al., 2015). This interindividual variation in MMR is consistent (repeatable) across time (Norin & Malte, 2011;Marras et al., 2010;Svendsen et al., 2014), although repeatability appears to be higher for SMR than for MMR both in a stable environment (Norin & Malte, 2011) and under different environmental conditions (Norin et al., 2015). There is evidence from O. mykiss that the origin of variation in MMR may be linked to the cardiovascular system (Claireaux et al., 2005). "
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    ABSTRACT: Maximum (aerobic) metabolic rate (MMR) is defined here as the maximum rate of oxygen consumption (M˙O2max ) that a fish can achieve at a given temperature under any ecologically relevant circumstance. Different techniques exist for eliciting MMR of fishes, of which swim-flume respirometry (critical swimming speed tests and burst-swimming protocols) and exhaustive chases are the most common. Available data suggest that the most suitable method for eliciting MMR varies with species and ecotype, and depends on the propensity of the fish to sustain swimming for extended durations as well as its capacity to simultaneously exercise and digest food. MMR varies substantially (>10 fold) between species with different lifestyles (i.e. interspecific variation), and to a lesser extent (<three-fold) between individuals of the same species (i.e. intraspecific variation). MMR often changes allometrically with body size and is modulated by several environmental factors, including temperature and oxygen availability. Due to the significance of MMR in determining aerobic scope, interest in measuring this trait has spread across disciplines in attempts to predict effects of climate change on fish populations. Here, various techniques used to elicit and measure MMR in different fish species with contrasting lifestyles are outlined and the relevance of MMR to the ecology, fitness and climate change resilience of fishes is discussed.
    Full-text · Article · Jan 2016 · Journal of Fish Biology
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