Does size matter for hypoxia tolerance in fish?

Abstract

Fish cover a large size range, from milligrams to tonnes, and many of them are regularly exposed to large variations in ambient oxygen levels. For more than half a century, there have been various, often divergent, claims regarding the effect of body size on hypoxia tolerance in fish. Here, we attempt to link old and new empirical data with the current understanding of the physiological mechanisms behind hypoxia tolerance. Three main conclusions are drawn: (1) body size per se has little or no impact on the ability to take up oxygen during hypoxic conditions, primarily because the respiratory surface area matches metabolic rate over a wide size range. If size-related differences are seen in the ability for oxygen uptake in a species, these are likely to reflect adaptation to different life-styles or habitat choice. (2) During severe hypoxia and anoxia, where fish have to rely on anaerobic ATP production (glycolysis) for survival, large individuals have a clear advantage over smaller ones, because small fish will run out of glycogen or reach lethal levels of anaerobic end-products (lactate and H(+)) much faster due to their higher mass-specific metabolic rate. (3) Those fish species that have evolved extreme adaptations to hypoxia, including haemoglobins with exceptionally high oxygen affinities and an alternative anaerobic end-product (ethanol), reveal that natural selection can be a much more powerful determinant of hypoxia tolerance than scaling of physiological functions.

Climate warming will test the limits of thermal plasticity in rainbow trout, a globally distributed fish

“…Strain comparisons must be made with caution because of differences in body size ( Supplementary Table S1 ). Nevertheless, our observations are inconsistent with previous research on other fish species that indicates that larger individuals may be more hypoxia tolerant than smaller ones ( Nilsson and Östlund-Nilsson, 2008 ; Roze et al., 2013 ; Hines et al., 2019 ) given a greater hypoxia tolerance was exhibited for the smaller Coleman strain. This observation suggests the potential for genetically or epigenetically mediated differences in hypoxia tolerance between the strains.…”

Climate warming will test the limits of thermal plasticity in rainbow trout, a globally distributed fish

“…Strain comparisons must be made with caution because of differences in body size ( Supplementary Table S1 ). Nevertheless, our observations are inconsistent with previous research on other fish species that indicates that larger individuals may be more hypoxia tolerant than smaller ones ( Nilsson and Östlund-Nilsson, 2008 ; Roze et al., 2013 ; Hines et al., 2019 ) given a greater hypoxia tolerance was exhibited for the smaller Coleman strain. This observation suggests the potential for genetically or epigenetically mediated differences in hypoxia tolerance between the strains.…”

Temperature and hypoxia‐driven shifts in Daphnia interspecific competition

“…The lack of a significant effect of hypoxia on the competitive ability within the first pair of species aligns with previous studies comparing the tolerance to hypoxia across different ectothermic species of varying body sizes, which have shown weak or insignificant trends (Nilsson and Ostlund‐Nilsson 2008; Seibel and Deutsch 2020). However, the results are not in line with the observations on the effects of hypoxia on the life history of ectotherms, which have shown that hypoxia reduces adult body size and offspring size, with more pronounced effects on physiological and life history parameters in larger‐bodied animals (Tran‐Duy et al 2008; Wilczynski et al 2019).…”

The impact of a strong natural hypoxic event on the toadfish Aphos porosus in Coliumo Bay, south-central Chile

“…1b and 3a), similar to what occurred in the stranding event occurred in Coliumo Bay in 1989 (Jara 1992). This is consistent with the reported high sensitivity of juvenile fish when exposed to hypoxia (Nilsson & Östlund-Nilsson 2008). From a physiological point of view, the length-mass relationships allowed us to determine the condition of this segment of the population of A. porosus.…”

Climate warming will test the limits of thermal plasticity in rainbow trout, a globally distributed fish

“…Strain comparisons must be made with caution because of differences in body size ( Supplementary Table S1 ). Nevertheless, our observations are inconsistent with previous research on other fish species that indicates that larger individuals may be more hypoxia tolerant than smaller ones ( Nilsson and Östlund-Nilsson, 2008 ; Roze et al., 2013 ; Hines et al., 2019 ) given a greater hypoxia tolerance was exhibited for the smaller Coleman strain. This observation suggests the potential for genetically or epigenetically mediated differences in hypoxia tolerance between the strains.…”

Temperature and hypoxia‐driven shifts in Daphnia interspecific competition

“…The lack of a significant effect of hypoxia on the competitive ability within the first pair of species aligns with previous studies comparing the tolerance to hypoxia across different ectothermic species of varying body sizes, which have shown weak or insignificant trends (Nilsson and Ostlund‐Nilsson 2008; Seibel and Deutsch 2020). However, the results are not in line with the observations on the effects of hypoxia on the life history of ectotherms, which have shown that hypoxia reduces adult body size and offspring size, with more pronounced effects on physiological and life history parameters in larger‐bodied animals (Tran‐Duy et al 2008; Wilczynski et al 2019).…”

The impact of a strong natural hypoxic event on the toadfish Aphos porosus in Coliumo Bay, south-central Chile

“…1b and 3a), similar to what occurred in the stranding event occurred in Coliumo Bay in 1989 (Jara 1992). This is consistent with the reported high sensitivity of juvenile fish when exposed to hypoxia (Nilsson & Östlund-Nilsson 2008). From a physiological point of view, the length-mass relationships allowed us to determine the condition of this segment of the population of A. porosus.…”

Climate warming will test the limits of thermal plasticity in rainbow trout, a globally distributed fish

“…Strain comparisons must be made with caution because of differences in body size ( Supplementary Table S1 ). Nevertheless, our observations are inconsistent with previous research on other fish species that indicates that larger individuals may be more hypoxia tolerant than smaller ones ( Nilsson and Östlund-Nilsson, 2008 ; Roze et al., 2013 ; Hines et al., 2019 ) given a greater hypoxia tolerance was exhibited for the smaller Coleman strain. This observation suggests the potential for genetically or epigenetically mediated differences in hypoxia tolerance between the strains.…”

Temperature and hypoxia‐driven shifts in Daphnia interspecific competition

“…The lack of a significant effect of hypoxia on the competitive ability within the first pair of species aligns with previous studies comparing the tolerance to hypoxia across different ectothermic species of varying body sizes, which have shown weak or insignificant trends (Nilsson and Ostlund‐Nilsson 2008; Seibel and Deutsch 2020). However, the results are not in line with the observations on the effects of hypoxia on the life history of ectotherms, which have shown that hypoxia reduces adult body size and offspring size, with more pronounced effects on physiological and life history parameters in larger‐bodied animals (Tran‐Duy et al 2008; Wilczynski et al 2019).…”

The impact of a strong natural hypoxic event on the toadfish Aphos porosus in Coliumo Bay, south-central Chile

“…1b and 3a), similar to what occurred in the stranding event occurred in Coliumo Bay in 1989 (Jara 1992). This is consistent with the reported high sensitivity of juvenile fish when exposed to hypoxia (Nilsson & Östlund-Nilsson 2008). From a physiological point of view, the length-mass relationships allowed us to determine the condition of this segment of the population of A. porosus.…”