Aerobic scope measurements of fishes in an era of climate change: respirometry, relevance and recommendations

Abstract

SummaryMeasurements of aerobic scope [the difference between minimum and maximum oxygen consumption rate (M O2,min and M O2,max , respectively)] are increasing in prevalence as a tool to address questions relating to fish ecology and the effects of climate change. However, there are underlying issues regarding the array of methods used to measure aerobic scope across studies and species. In an attempt to enhance quality control before the diversity of issues becomes too great to remedy, this paper outlines common techniques and pitfalls associated with measurements of M O2,min , M O2,max and aerobic scope across species and under different experimental conditions. Additionally, we provide a brief critique of the oxygen-and capacity-limited thermal tolerance (OCLTT) hypothesis, a concept that is intricately dependent on aerobic scope measurements and is spreading wildly throughout the literature despite little evidence for its general applicability. It is the intention of this paper to encourage transparency and accuracy in future studies that measure the aerobic metabolism of fishes, and to highlight the fundamental issues with assuming broad relevance of the OCLTT hypothesis.

Variation in Metabolic Rate among Individuals Is Related to Tissue-Specific Differences in Mitochondrial Leak Respiration

“…SMR for each fish was calculated by taking the mean of the lowest tenth percentile of oxygen consumption measurements over the 20-h measurement period and then excluding outliers, that is, those measurements below 2 SD from this mean (Clark et al 2013).…”

Ecological Influences and Morphological Correlates of Resting and Maximal Metabolic Rates across Teleost Fish Species

“…Absolute aerobic scope (AS = MMR -RMR) theoretically sets the capacity for simultaneous oxygen-consuming processes above maintenance levels, including activity, digestion and assimilation of nutrients, and coping with stressors or disease (Claireaux and Lefrancois 2007;Clark et al 2013b;Fry 1971), whereas factorial aerobic scope (FAS = MMR/RMR) provides a relative measure of the maximum capacity for energy turnover with respect to resting expenditure rates, and is assumed to be relatively constant according to the aerobic capacity model (Rubenstein 2012). Because AS and FAS have different biological interpretations and may be associated with different ecological pressures (Clark et al 2013b), we analysed how both of these measures of aerobic scope covary with RMR and MMR.…”

“…Because AS and FAS have different biological interpretations and may be associated with different ecological pressures (Clark et al 2013b), we analysed how both of these measures of aerobic scope covary with RMR and MMR. Our second major goal was to test for associations between whole-organismal performance and relevant ecological variables on the one hand, and various key morphological traits on the other to identify, respectively, possible ultimate and proximate causes of the variation in metabolic rates that we observed.…”

Thermal acclimation and subspecies-specific effects on heart and brain mitochondrial performance in a eurythermal teleost (Fundulus heteroclitus)

“…Alternatively, temperature-induced declines in neural function are suggested to constrain thermal performance limits (Somero and DeVries, 1967;Ern et al, 2015;Cossins, 1977;Jastroch et al, 2007;Miller and Stillman, 2012). However, the relative importance of these organ systems in setting an organism's thermal performance limits is still subject to debate (Clark et al, 2013;Ern et al, 2015).…”