The autonomic control and functional significance of the changes in heart rate associated with air breathing in the jeju,<i>Hoplerythrinus unitaeniatus</i>

McKenzie, David J.; Campbell, Hamish A.; Taylor, E. W.; Micheli, M; Rantin, Francisco Tadeu; Abe, Augusto Shinya

doi:10.1242/jeb.009266

Cited by 51 publications

(39 citation statements)

References 33 publications

(71 reference statements)

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“…Catfish were fasted for 24 h prior to measurements in either condition, then individuals were transferred gently to respirometers without air exposure, to minimise effects of handling. There were four respirometer chambers immersed in well-aerated water in an outer bath (1 m 2 surface area, 21 cm water depth) with the entire setup screened behind tarpaulin so that routine air-breathing behaviour was not inhibited by fear of human presence (McKenzie et al, 1991(McKenzie et al, , 2007Shingles et al, 2005). Fish were placed in the respirometer in the evening between 18:00 h and 20:00 h and fish were then allowed 16 h to recover from handling.…”

Section: Bimodal Respirometrymentioning

confidence: 99%

“…The alternate period was when the two phases, aquatic and aerial, were flushed simultaneously for 5 min to replenish O 2 levels. Aquatic hypoxia was created and controlled as described previously, with corrections made for rates of passive diffusion of O 2 from air to water (McKenzie et al, 2007. Details of the system are provided in Lefevre et al (2016).…”

Section: Bimodal Respirometrymentioning

confidence: 99%

“…) for each 15 min respirometry cycle, based upon the decline in O 2 content in each phase during the closed period, as described previously (McKenzie et al, 2007. The ṀO 2,water and ṀO 2,air were summed to calculate RMR.…”

Section: Bimodal Respirometrymentioning

confidence: 99%

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To boldly gulp: standard metabolic rate and boldness have context-dependent influences on risk-taking to breathe air in a catfish

McKenzie

Belão

Killen

et al. 2015

Journal of Experimental Biology

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The African sharptooth catfish Clarias gariepinus has bimodal respiration, it has a suprabranchial air-breathing organ alongside substantial gills. We used automated bimodal respirometry to reveal that undisturbed juvenile catfish (N=29) breathed air continuously in normoxia, with a marked diurnal cycle. Air breathing and routine metabolic rate (RMR) increased in darkness when, in the wild, this nocturnal predator forages. Aquatic hypoxia (20% air saturation) greatly increased overall reliance on air breathing. We investigated whether two measures of risk taking to breathe air, namely absolute rates of aerial O 2 uptake (Ṁ O2,air ) and the percentage of RMR obtained from air (%Ṁ O2,air ), were influenced by individual standard metabolic rate (SMR) and boldness. In particular, whether any influence varied with resource availability (normoxia versus hypoxia) or relative fear of predation (day versus night). Individual SMR, derived from respirometry, had an overall positive influence on Ṁ O2,air across all contexts but a positive influence on %Ṁ O2,air only in hypoxia. Thus, a pervasive effect of SMR on air breathing became most acute in hypoxia, when individuals with higher O 2 demand took proportionally more risks. Boldness was estimated as time required to resume air breathing after a fearful stimulus in daylight normoxia (T res ). Although T res had no overall influence on Ṁ O2,air or %Ṁ O2,air , there was a negative relationship between T res and %Ṁ O2,air in daylight, in normoxia and hypoxia. There were two T res response groups, 'bold' phenotypes with T res below 75 min (N=13) which, in daylight, breathed proportionally more air than 'shy' phenotypes with T res above 115 min (N=16). Therefore, individual boldness influenced air breathing when fear of predation was high. Thus, individual energy demand and personality did not have parallel influences on the emergent tendency to take risks to obtain a resource; their influences varied in strength with context.

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Section: Bimodal Respirometrymentioning

confidence: 99%

Section: Bimodal Respirometrymentioning

confidence: 99%

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To boldly gulp: standard metabolic rate and boldness have context-dependent influences on risk-taking to breathe air in a catfish

McKenzie

Belão

Killen

et al. 2015

Journal of Experimental Biology

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“…Water oxygen concentration was recorded continuously using an optical oxygen probe and meter (Fibox, PreSens GmbH, www.presens.de) and M wO2 was calculated automatically with Loliresp software (Loligo Systems, www.loligosystems.com), considering the rate of decline in oxygen concentration, the water volume in the swim tunnel and the mass of the fish (Steffensen, 1989). Oxygen uptake from the air (M aO2 ) was measured as described previously (McKenzie et al, 2007a), using an optical fibre optode (Microx, PreSens GmbH) and associated software (PreSens Oxyview) continuously to monitor air P O2 . The M aO2 was calculated considering the rate of decline in oxygen concentration in the air space, the air volume and the mass of the fish (Randall et al, 1981b).…”

Section: Swimming Respirometrymentioning

confidence: 99%

“…The percentages of M tO2 taken up from water or air were then calculated. In aquatic hypoxia, there was a net diffusion of oxygen from the air space into the water (McKenzie et al, 2007a). To correct for this, tests were run at each swimming speed with no fish, and rates of oxygen decline from the air, and increase in the water, were calculated.…”

Section: Swimming Respirometrymentioning

confidence: 99%

The contribution of air breathing to aerobic scope and exercise performance in the banded knifefishGymnotus carapoL.

McKenzie

Steffensen

Taylor

et al. 2012

Journal of Experimental Biology

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SUMMARY The contribution of air breathing to aerobic metabolic scope and exercise performance was investigated in a teleost with bimodal respiration, the banded knifefish, submitted to a critical swimming speed (Ucrit) protocol at 30°C. Seven individuals (mean ± s.e.m. mass 89±7 g, total length 230±4 mm) achieved a Ucrit of 2.1±1 body lengths (BL) s–1 and an active metabolic rate (AMR) of 350±21 mg kg–1 h–1, with 38±6% derived from air breathing. All of the knifefish exhibited a significant increase in air-breathing frequency (fAB) with swimming speed. If denied access to air in normoxia, these individuals achieved a Ucrit of 2.0±0.2 BL s–1 and an AMR of 368±24 mg kg–1 h–1 by gill ventilation alone. In normoxia, therefore, the contribution of air breathing to scope and exercise was entirely facultative. In aquatic hypoxia (PO2=4 kPa) with access to normoxic air, the knifefish achieved a Ucrit of 2.0±0.1 BL s–1 and an AMR of 338±29 mg kg–1 h–1, similar to aquatic normoxia, but with 55±5% of AMR derived from air breathing. Indeed, fAB was higher than in normoxia at all swimming speeds, with a profound exponential increase during exercise. If the knifefish were denied access to air in hypoxia, Ucrit declined to 1.2±0.1 BL s–1 and AMR declined to 199±29 mg kg–1 h–1. Therefore, air breathing allowed the knifefish to avoid limitations to aerobic scope and exercise performance in aquatic hypoxia.

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Striped catfish (Pangasianodon hypophthalmus) use air‐breathing and aquatic surface respiration when exposed to severe aquatic hypercarbia

et al. 2021

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We investigated the extent to which the facultative air‐breathing fish, the striped catfish (Pangasianodon hypophthalmus), uses air‐breathing to cope with aquatic hypercarbia, and how air‐breathing is influenced by the experimental exposure protocol and level of hypercarbia. We exposed individuals to severe aquatic hypercarbia (up to PwCO2 = 81 mmHg) using step‐wise and progressive exposure protocols while measuring gill ventilation rate, heart rate, mean arterial blood pressure, and air‐breathing frequency, as well as arterial blood pH and PCO2. We confirm that P. hypophthalmus is tolerant of hypercarbia. Under both protocols gill ventilation rate, heart rate, and mean arterial blood pressure were maintained near control levels even at very high CO2 levels. We observed a marked amount of individual variation in the PwCO2 at which air‐breathing was elicited, with some individuals not responding at all. The experimental protocol also influenced the onset of air‐breathing. Air‐breathing began at lower PwCO2 in the step‐wise protocol (23 ± 4.1 mmHg) compared with the progressive protocol (46 ± 7.8 mmHg). Air‐breathing was often followed by aquatic surface respiration, at higher PCO2 (71 ± 5.2 mmHg) levels. On average, the blood PCO2 was approximately 43% lower (46 ± 2.5 mmHg) than water PwCO2 (~81 mmHg) at our highest tested CO2 level. While this suggests that aerial CO2 elimination is an effective, and perhaps critical, respiratory strategy used by P. hypophthalmus to cope with severe hypercarbia, this observation may also be explained by a long lag time required for equilibration.

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The autonomic control and functional significance of the changes in heart rate associated with air breathing in the jeju,Hoplerythrinus unitaeniatus

Cited by 51 publications

References 33 publications

To boldly gulp: standard metabolic rate and boldness have context-dependent influences on risk-taking to breathe air in a catfish

To boldly gulp: standard metabolic rate and boldness have context-dependent influences on risk-taking to breathe air in a catfish

The contribution of air breathing to aerobic scope and exercise performance in the banded knifefishGymnotus carapoL.

Striped catfish (Pangasianodon hypophthalmus) use air‐breathing and aquatic surface respiration when exposed to severe aquatic hypercarbia

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