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McArley TJ, Morgenroth D, Zena LA, Ekström AT, Sandblom E. Prevalence and mechanisms of environmental hyperoxia-induced thermal tolerance in fishes. Proc Biol Sci 2022; 289:20220840. [PMID: 35975439 PMCID: PMC9382203 DOI: 10.1098/rspb.2022.0840] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Recent evidence has suggested environmental hyperoxia (O2 supersaturation) can boost cardiorespiratory performance in aquatic ectotherms, thereby increasing resilience to extreme heat waves associated with climate change. Here, using rainbow trout (Oncorhynchus mykiss) as a model species, we analysed whether improved cardiorespiratory performance can explain the increased thermal tolerance of fish in hyperoxia (200% air saturation). Moreover, we collated available literature data to assess the prevalence and magnitude of hyperoxia-induced thermal tolerance across fish species. During acute warming, O2 consumption rate was substantially elevated under hyperoxia relative to normoxia beyond 23°C. This was partly driven by higher cardiac output resulting from improved cardiac contractility. Notably, hyperoxia mitigated the rise in plasma lactate at temperatures approaching upper limits and elevated the critical thermal maximum (+0.87°C). Together, these findings show, at least in rainbow trout, that hyperoxia-induced thermal tolerance results from expanded tissue O2 supply capacity driven by enhanced cardiac performance. We show 50% of the fishes so far examined have increased critical thermal limits in hyperoxia (range: 0.4-1.8°C). This finding indicates environmental hyperoxia could improve the ability of a large number of fishes to cope with extreme acute warming, thereby increasing resilience to extreme heat wave events resulting from climate change.
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Affiliation(s)
- T. J. McArley
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
| | - D. Morgenroth
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
| | - L. A. Zena
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
| | - A. T. Ekström
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
| | - E. Sandblom
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
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2
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McArley TJ, Morgenroth D, Zena LA, Ekström AT, Sandblom E. Normoxic limitation of maximal oxygen consumption rate, aerobic scope and cardiac performance in exhaustively exercised rainbow trout (Oncorhynchus mykiss). J Exp Biol 2021; 224:271087. [PMID: 34323276 DOI: 10.1242/jeb.242614] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 06/25/2021] [Indexed: 01/22/2023]
Abstract
In fish, maximum O2 consumption rate (ṀO2,max) and aerobic scope can be expanded following exhaustive exercise in hyperoxia; however, the mechanisms explaining this are yet to be identified. Here, in exhaustively exercised rainbow trout (Oncorhynchus mykiss), we assessed the influence of hyperoxia on ṀO2,max, aerobic scope, cardiac function and blood parameters to address this knowledge gap. Relative to normoxia, ṀO2,max was 33% higher under hyperoxia, and this drove a similar increase in aerobic scope. Cardiac output was significantly elevated under hyperoxia at ṀO2,max because of increased stroke volume, indicating that hyperoxia released a constraint on cardiac contractility apparent with normoxia. Thus, hyperoxia improved maximal cardiac performance, thereby enhancing tissue O2 delivery and allowing a higher ṀO2,max. Venous blood O2 partial pressure (PvO2) was elevated in hyperoxia at ṀO2,max, suggesting a contribution of improved luminal O2 supply in enhanced cardiac contractility. Additionally, despite reduced haemoglobin and higher PvO2, hyperoxia treated fish retained a higher arterio-venous O2 content difference at ṀO2,max. This may have been possible because of hyperoxia offsetting declines in arterial oxygenation that are known to occur following exhaustive exercise in normoxia. If this occurs, increased contractility at ṀO2,max with hyperoxia may also relate to an improved O2 supply to the compact myocardium via the coronary artery. Our findings show ṀO2,max and aerobic scope may be limited in normoxia following exhaustive exercise as a result of constrained maximal cardiac performance and highlight the need to further examine whether or not exhaustive exercise protocols are suitable for eliciting ṀO2,max and estimating aerobic scope in rainbow trout.
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Affiliation(s)
- Tristan J McArley
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
| | - Daniel Morgenroth
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
| | - Lucas A Zena
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
| | - Andreas T Ekström
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
| | - Erik Sandblom
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
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3
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O'Brien KM, Joyce W, Crockett EL, Axelsson M, Egginton S, Farrell AP. Resilience of cardiac performance in Antarctic notothenioid fishes in a warming climate. J Exp Biol 2021; 224:268390. [PMID: 34042975 DOI: 10.1242/jeb.220129] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Warming in the region of the Western Antarctic Peninsula is occurring at an unprecedented rate, which may threaten the survival of Antarctic notothenioid fishes. Herein, we review studies characterizing thermal tolerance and cardiac performance in notothenioids - a group that includes both red-blooded species and the white-blooded, haemoglobinless icefishes - as well as the relevant biochemistry associated with cardiac failure during an acute temperature ramp. Because icefishes do not feed in captivity, making long-term acclimation studies unfeasible, we focus only on the responses of red-blooded notothenioids to warm acclimation. With acute warming, hearts of the white-blooded icefish Chaenocephalus aceratus display persistent arrhythmia at a lower temperature (8°C) compared with those of the red-blooded Notothenia coriiceps (14°C). When compared with the icefish, the enhanced cardiac performance of N. coriiceps during warming is associated with greater aerobic capacity, higher ATP levels, less oxidative damage and enhanced membrane integrity. Cardiac performance can be improved in N. coriiceps with warm acclimation to 5°C for 6-9 weeks, accompanied by an increase in the temperature at which cardiac failure occurs. Also, both cardiac mitochondrial and microsomal membranes are remodelled in response to warm acclimation in N. coriiceps, displaying homeoviscous adaptation. Overall, cardiac performance in N. coriiceps is malleable and resilient to warming, yet thermal tolerance and plasticity vary among different species of notothenioid fishes; disruptions to the Antarctic ecosystem driven by climate warming and other anthropogenic activities endanger the survival of notothenioids, warranting greater protection afforded by an expansion of marine protected areas.
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Affiliation(s)
- Kristin M O'Brien
- Institute of Arctic Biology , University of Alaska Fairbanks, Fairbanks, AK 99775-7000, USA
| | - William Joyce
- Department of Biology - Zoophysiology, Aarhus University, 8000 Aarhus C, Denmark
| | | | - Michael Axelsson
- Department of Biological and Environmental Sciences, University of Gothenburg, 40530 Gothenburg, Sweden
| | - Stuart Egginton
- School of Biomedical Sciences , University of Leeds, Leeds LS2 9JT, UK
| | - Anthony P Farrell
- Department of Zoology, and Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
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4
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Leeuwis RHJ, Zanuzzo FS, Peroni EFC, Gamperl AK. Research on sablefish ( Anoplopoma fimbria) suggests that limited capacity to increase heart function leaves hypoxic fish susceptible to heat waves. Proc Biol Sci 2021; 288:20202340. [PMID: 33715435 PMCID: PMC7944113 DOI: 10.1098/rspb.2020.2340] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 02/11/2021] [Indexed: 01/19/2023] Open
Abstract
Studies of heart function and metabolism have been used to predict the impact of global warming on fish survival and distribution, and their susceptibility to acute and chronic temperature increases. Yet, despite the fact that hypoxia and high temperatures often co-occur, only one study has examined the effects of hypoxia on fish thermal tolerance, and the consequences of hypoxia for fish cardiac responses to acute warming have not been investigated. We report that sablefish (Anoplopoma fimbria) did not increase heart rate or cardiac output when warmed while hypoxic, and that this response was associated with reductions in maximum O2 consumption and thermal tolerance (CTmax) of 66% and approximately 3°C, respectively. Further, acclimation to hypoxia for four to six months did not substantially alter the sablefish's temperature-dependent physiological responses or improve its CTmax. These results provide novel, and compelling, evidence that hypoxia can impair the cardiac and metabolic response to increased temperatures in fish, and suggest that some coastal species may be more vulnerable to climate change-related heat waves than previously thought. Further, they support research showing that cross-tolerance and physiological plasticity in fish following hypoxia acclimation are limited.
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Affiliation(s)
- Robine H. J. Leeuwis
- Department of Ocean Sciences, Memorial University of Newfoundland, St John's, NL, Canada A1C 5S7
| | - Fábio S. Zanuzzo
- Department of Ocean Sciences, Memorial University of Newfoundland, St John's, NL, Canada A1C 5S7
| | - Ellen F. C. Peroni
- Department of Ocean Sciences, Memorial University of Newfoundland, St John's, NL, Canada A1C 5S7
| | - A. Kurt Gamperl
- Department of Ocean Sciences, Memorial University of Newfoundland, St John's, NL, Canada A1C 5S7
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5
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Lawrence MJ, Eliason EJ, Zolderdo AJ, Lapointe D, Best C, Gilmour KM, Cooke SJ. Cortisol modulates metabolism and energy mobilization in wild-caught pumpkinseed (Lepomis gibbosus). FISH PHYSIOLOGY AND BIOCHEMISTRY 2019; 45:1813-1828. [PMID: 31300974 DOI: 10.1007/s10695-019-00680-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 06/26/2019] [Indexed: 06/10/2023]
Abstract
Acute elevation of cortisol via activation of the hypothalamic-pituitary-interrenal (HPI) axis aids the fish in dealing with a stressor. However, chronic elevation of cortisol has detrimental effects and has been studied extensively in lab settings. However, data pertaining to wild teleosts are lacking. Here, we characterized the metabolic consequences of prolonged cortisol elevation (96 h) in wild-caught pumpkinseed (Lepomis gibbosus). Pumpkinseed were implanted with cocoa butter alone (sham) or containing cortisol (25 mg kg-1 body weight), and at 24, 48, 72, and 96 h, tissue samples were collected, whole-body ammonia excretion was determined, and whole-organism metabolism was assessed using intermittent flow respirometry. Cortisol-treated pumpkinseed exhibited the highest plasma cortisol concentration at 24 h post-implantation, with levels decreasing over the subsequent time points although remaining higher than in sham-treated fish. Cortisol-treated fish exhibited higher standard and maximal metabolic rates than sham-treated fish, but the effect of cortisol treatment on aerobic scope was negligible. Indices of energy synthesis/mobilization, including blood glucose concentrations, hepatosomatic index, hepatic glycogen concentrations, and ammonia excretion rates, were higher in cortisol-treated fish compared with controls. Our work suggests that although aerobic scope was not diminished by prolonged elevation of cortisol levels, higher metabolic expenditures may be of detriment to the animal's performance in the longer term.
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Affiliation(s)
- Michael J Lawrence
- Fish Ecology and Conservation Physiology Laboratory, Department of Biology, Carleton University, Ottawa, ON, K1S 5B6, Canada.
| | - Erika J Eliason
- Department of Ecology, Evolution & Marine Biology, University of California, Santa Barbara, CA, 93117, USA
| | - Aaron J Zolderdo
- Fish Ecology and Conservation Physiology Laboratory, Department of Biology, Carleton University, Ottawa, ON, K1S 5B6, Canada
- Queen's University Biological Station, Queen's University, Elgin, ON, K0G 1E0, Canada
| | - Dominique Lapointe
- St. Lawrence River Institute of Environmental Sciences, Cornwall, ON, K6H 4Z1, Canada
| | - Carol Best
- Department of Biology, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - Kathleen M Gilmour
- Department of Biology, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - Steven J Cooke
- Fish Ecology and Conservation Physiology Laboratory, Department of Biology, Carleton University, Ottawa, ON, K1S 5B6, Canada
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6
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Zhang Y, Polinski MP, Morrison PR, Brauner CJ, Farrell AP, Garver KA. High-Load Reovirus Infections Do Not Imply Physiological Impairment in Salmon. Front Physiol 2019; 10:114. [PMID: 30930782 PMCID: PMC6425399 DOI: 10.3389/fphys.2019.00114] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 01/30/2019] [Indexed: 12/14/2022] Open
Abstract
The recent ubiquitous detection of PRV among salmonids has sparked international concern about the cardiorespiratory performance of infected wild and farmed salmon. Piscine orthoreovirus (PRV) has been shown to create substantial viremia in salmon by targeting erythrocytes for principle replication. In some instances, infections develop into heart and skeletal muscle inflammation (HSMI) or other pathological conditions affecting the respiratory system. Critical to assessing the seriousness of PRV infections are controlled infection studies that measure physiological impairment to critical life support systems. Respiratory performance is such a system and here multiple indices were measured to test the hypothesis that a low-virulence strain of PRV from Pacific Canada compromises the cardiorespiratory capabilities of Atlantic salmon. Contrary to this hypothesis, the oxygen affinity and carrying capacity of erythrocytes were unaffected by PRV despite the presence of severe viremia, minor heart pathology and transient cellular activation of antiviral response pathways. Similarly, PRV-infected fish had neither sustained nor appreciable differences in respiratory capabilities compared with control fish. The lack of functional harm to salmon infected with PRV in this instance highlights that, in an era of unprecedented virus discovery, detection of viral infection does not necessarily imply bodily harm and that viral load is not always a suitable predictor of disease within a host organism.
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Affiliation(s)
- Yangfan Zhang
- Faculty of Land and Food Systems, The University of British Columbia, Vancouver, BC, Canada
| | - Mark P Polinski
- Aquatic Diagnostics and Genomics Division, Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, BC, Canada
| | - Phillip R Morrison
- Department of Zoology, The University of British Columbia, Vancouver, BC, Canada
| | - Colin J Brauner
- Department of Zoology, The University of British Columbia, Vancouver, BC, Canada
| | - Anthony P Farrell
- Faculty of Land and Food Systems, The University of British Columbia, Vancouver, BC, Canada.,Department of Zoology, The University of British Columbia, Vancouver, BC, Canada
| | - Kyle A Garver
- Aquatic Diagnostics and Genomics Division, Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, BC, Canada
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7
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Joyce W, Egginton S, Farrell AP, Crockett EL, O'Brien KM, Axelsson M. Exploring nature's natural knockouts: in vivo cardiorespiratory performance of Antarctic fishes during acute warming. ACTA ACUST UNITED AC 2018; 221:jeb.183160. [PMID: 29967219 DOI: 10.1242/jeb.183160] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 06/25/2018] [Indexed: 01/09/2023]
Abstract
We tested the hypothesis that blackfin icefish (Chaenocephalus aceratus), one of the six species in the family Channichthyidae (the icefishes) that do not express haemoglobin and myoglobin, lack regulatory cardiovascular flexibility during acute warming and activity. The experimental protocols were designed to optimize the surgical protocol and minimize stress. First, minimally invasive heart rate (fH) measurements were made during a thermal ramp until cardiac failure in C. aceratus and compared with those from the closely related red-blooded black rockcod (Notothenia coriiceps). Then, integrative cardiovascular adjustments were more extensively studied using flow probes and intravascular catheters in C. aceratus during acute warming (from 0 to 8°C) at rest and after imposed activity. Chaenocephalus aceratus had a lower routine fH than N. coriiceps (9 beats min-1 versus 14 beats min-1) and a lower peak fH during acute warming (38 beats min-1 versus 55 beats min-1) with a similar cardiac breakpoint temperature (13 and 14°C, respectively). Routine cardiac output (Q̇) for C. aceratus at ∼0°C was much lower (26.6 ml min-1 kg-1) than previously reported, probably because fish in the present study had a low fH (12 beats min-1) indicative of a high routine vagal tone and low stress. Chaenocephalus aceratus increased oxygen consumption during acute warming and with activity. Correspondingly, Q̇ increased considerably (maximally 86.3 ml min-1 kg-1), as did vascular conductance (5-fold). Thus, unlike earlier suggestions, these data provide convincing evidence that icefish can mount a well-developed cardiovascular regulation of heart rate, cardiac output and vascular conductance, and this regulatory capacity provides flexibility during acute warming.
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Affiliation(s)
- William Joyce
- Department of Zoophysiology, Aarhus University, 8000 Aarhus C, Denmark
| | - Stuart Egginton
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Anthony P Farrell
- Department of Zoology, and Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC 45, Canada
| | | | - Kristin M O'Brien
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775-7000, USA
| | - Michael Axelsson
- Department of Biological and Environmental Sciences, University of Gothenburg, 4139 90 Gothenburg, Sweden
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8
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Wainwright DK, Ingersoll S, Lauder GV. Scale diversity in bigeye tuna (Thunnus obesus): Fat-filled trabecular scales made of cellular bone. J Morphol 2018. [PMID: 29537097 DOI: 10.1002/jmor.20814] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Tunas of the genus Thunnus possess many morphological and physiological adaptations for their high-performance epipelagic ecology. Although Thunnus anatomy has been studied, there are no quantitative studies on the structure of their scales. We investigated the scales of bigeye tuna (Thunnus obesus) from ten regions of the body using micro computed tomography (µCT)-scanning and histology to quantitatively and qualitatively compare regional scale morphology. We found a diversity of scale sizes and shapes across the body of bigeye tuna and discriminant function analysis on variables derived from µCT-data showed that scales across the body differ quantitatively in shape and size. We also report the discovery of a novel scale type in corselet, tail, and cheek regions. These modified scales are ossified shells supported by internal trabeculae, filled with fat, and possessing an internal blood supply. Histological analysis showed that the outer lamellar layers of these thickened scales are composed of cellular bone, unexpected for a perciform fish in which bone is typically acellular. In the fairing region of the anterior body, these fat-filled scales are stacked in layers up to five scales deep, forming a thickened bony casing. Cheek scales also possess a fat-filled internal trabecular structure, while most posterior body scales are more plate-like and similar to typical teleost scales. While the function of these novel fat-filled scales is unknown, we explore several possible hypotheses for their function.
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Affiliation(s)
- Dylan K Wainwright
- Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts
| | - Sam Ingersoll
- Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts
| | - George V Lauder
- Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts
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9
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Joyce W, Axelsson M, Egginton S, Farrell AP, Crockett EL, O’Brien KM. The effects of thermal acclimation on cardio-respiratory performance in an Antarctic fish ( Notothenia coriiceps). CONSERVATION PHYSIOLOGY 2018; 6:coy069. [PMID: 30568798 PMCID: PMC6291619 DOI: 10.1093/conphys/coy069] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 11/13/2018] [Accepted: 11/26/2018] [Indexed: 05/21/2023]
Abstract
The Southern Ocean has experienced stable, cold temperatures for over 10 million years, yet particular regions are currently undergoing rapid warming. To investigate the impacts of warming on cardiovascular oxygen transport, we compared the cardio-respiratory performance in an Antarctic notothenioid (Notothenia coriiceps) that was maintained at 0 or 5°C for 6.0-9.5 weeks. When compared at the fish's respective acclimation temperature, the oxygen consumption rate and cardiac output were significantly higher in 5°C-acclimated than 0°C-acclimated fish. The 2.7-fold elevation in cardiac output in 5°C-acclimated fish (17.4 vs. 6.5 ml min-1 kg-1) was predominantly due to a doubling of stroke volume, likely in response to increased cardiac preload, as measured by higher central venous pressure (0.15 vs. 0.08 kPa); tachycardia was minor (29.5 vs. 25.2 beats min-1). When fish were acutely warmed, oxygen consumption rate increased by similar amounts in 0°C- and 5°C-acclimated fish at equivalent test temperatures. In both acclimation groups, the increases in oxygen consumption rate during acute heating were supported by increased cardiac output achieved by elevating heart rate, while stroke volume changed relatively little. Cardiac output was similar between both acclimation groups until 12°C when cardiac output became significantly higher in 5°C-acclimated fish, driven largely by their higher stroke volume. Although cardiac arrhythmias developed at a similar temperature (~14.5°C) in both acclimation groups, the hearts of 5°C-acclimated fish continued to pump until significantly higher temperatures (CTmax for cardiac function 17.7 vs. 15.0°C for 0°C-acclimated fish). These results demonstrate that N. coriiceps is capable of increasing routine cardiac output during both acute and chronic warming, although the mechanisms are different (heart rate-dependent versus primarily stroke volume-dependent regulation, respectively). Cardiac performance was enhanced at higher temperatures following 5°C acclimation, suggesting cardiovascular function may not constrain the capacity of N. coriiceps to withstand a warming climate.
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Affiliation(s)
- William Joyce
- Department of Zoophysiology, Aarhus University, Aarhus C, Denmark
- Corresponding author: Department of Zoophysiology, Aarhus University, 8000 Aarhus C, Denmark.
| | - Michael Axelsson
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Stuart Egginton
- School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - Anthony P Farrell
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | | | - Kristin M O’Brien
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, USA
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10
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Harter TS, Brauner CJ. The O 2 and CO 2 Transport System in Teleosts and the Specialized Mechanisms That Enhance Hb–O 2 Unloading to Tissues. ACTA ACUST UNITED AC 2017. [DOI: 10.1016/bs.fp.2017.09.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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11
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12
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13
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Ekström A, Brijs J, Clark TD, Gräns A, Jutfelt F, Sandblom E. Cardiac oxygen limitation during an acute thermal challenge in the European perch: effects of chronic environmental warming and experimental hyperoxia. Am J Physiol Regul Integr Comp Physiol 2016; 311:R440-9. [PMID: 27280433 DOI: 10.1152/ajpregu.00530.2015] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 06/07/2016] [Indexed: 11/22/2022]
Abstract
Oxygen supply to the heart has been hypothesized to limit cardiac performance and whole animal acute thermal tolerance (CTmax) in fish. We tested these hypotheses by continuously measuring venous oxygen tension (Pvo2) and cardiovascular variables in vivo during acute warming in European perch (Perca fluviatilis) from a reference area during summer (18°C) and a chronically heated area (Biotest enclosure) that receives warm effluent water from a nuclear power plant and is normally 5-10°C above ambient (24°C at the time of experiments). While CTmax was 2.2°C higher in Biotest compared with reference perch, the peaks in cardiac output and heart rate prior to CTmax occurred at statistically similar Pvo2 values (2.3-4.0 kPa), suggesting that cardiac failure occurred at a common critical Pvo2 threshold. Environmental hyperoxia (200% air saturation) increased Pvo2 across temperatures in reference fish, but heart rate still declined at a similar temperature. CTmax of reference fish increased slightly (by 0.9°C) in hyperoxia, but remained significantly lower than in Biotest fish despite an improved cardiac output due to an elevated stroke volume. Thus, while cardiac oxygen supply appears critical to elevate stroke volume at high temperatures, oxygen limitation may not explain the bradycardia and arrhythmia that occur prior to CTmax Acute thermal tolerance and its thermal plasticity can, therefore, only be partially attributed to cardiac failure from myocardial oxygen limitations, and likely involves limiting factors on multiple organizational levels.
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Affiliation(s)
- Andreas Ekström
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden;
| | - Jeroen Brijs
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Timothy D Clark
- Australian Institute of Marine Science, Townsville, Queensland, Australia; and
| | - Albin Gräns
- Department of Animal Environment and Health, Swedish University of Agricultural Sciences, Skara, Sweden
| | - Fredrik Jutfelt
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Erik Sandblom
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
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14
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Brijs J, Gräns A, Ekström A, Olsson C, Axelsson M, Sandblom E. Cardiorespiratory upregulation during seawater acclimation in rainbow trout: effects on gastrointestinal perfusion and postprandial responses. Am J Physiol Regul Integr Comp Physiol 2016; 310:R858-65. [PMID: 26911464 DOI: 10.1152/ajpregu.00536.2015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 02/17/2016] [Indexed: 11/22/2022]
Abstract
Increased gastrointestinal blood flow is essential for euryhaline fishes to maintain osmotic homeostasis during the initial phase of a transition from freshwater to seawater. However, the cardiorespiratory responses and hemodynamic changes required for a successful long-term transition to seawater remain largely unknown. In the present study, we simultaneously measured oxygen consumption rate (ṀO2), cardiac output (CO), heart rate (HR), and gastrointestinal blood flow (GBF) in rainbow trout (Oncorhynchus mykiss) acclimated to either freshwater or seawater for at least 6 wk. Seawater-acclimated trout displayed significantly elevated ṀO2 (day: 18%, night: 19%), CO (day: 22%, night: 48%), and GBF (day: 96%, night: 147%), demonstrating that an overall cardiorespiratory upregulation occurs during seawater acclimation. The elevated GBF was achieved via a combination of increased CO, mediated through elevated stroke volume (SV), and a redistribution of blood flow to the gastrointestinal tract. Interestingly, virtually all of the increase in CO of seawater-acclimated trout was directed to the gastrointestinal tract. Although unfed seawater-acclimated trout displayed substantially elevated cardiorespiratory activity, the ingestion of a meal resulted in a similar specific dynamic action (SDA) and postprandial GBF response as in freshwater-acclimated fish. This indicates that the capacity for the transportation of absorbed nutrients, gastrointestinal tissue oxygen delivery, and acid-base regulation is maintained during digestion in seawater. The novel findings presented in this study clearly demonstrate that euryhaline fish upregulate cardiovascular function when in seawater, while retaining sufficient capacity for the metabolic and cardiovascular changes associated with the postprandial response.
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Affiliation(s)
- Jeroen Brijs
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden; and
| | - Albin Gräns
- Department of Animal Environment and Health, Swedish University of Agricultural Sciences, Skara, Sweden
| | - Andreas Ekström
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden; and
| | - Catharina Olsson
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden; and
| | - Michael Axelsson
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden; and
| | - Erik Sandblom
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden; and
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15
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Gold DK, Loirat T, Farrell AP. Cardiorespiratory responses to haemolytic anaemia in rainbow trout Oncorhynchus mykiss. JOURNAL OF FISH BIOLOGY 2015; 87:848-859. [PMID: 26282915 DOI: 10.1111/jfb.12742] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 06/12/2015] [Indexed: 06/04/2023]
Abstract
To quantify cardiorespiratory response to experimental anaemia in rainbow trout Oncorhynchus mykiss, a 24 h phenylhydrazine treatment was used to reduce haematocrit to almost one third of its initial value over 4-5 days. In response, relative blood velocity in the ventral aorta (an index of cardiac output) progressively increased to more than double to its normocythaemic value and there was no significant change in routine oxygen uptake. Thus, the primary compensatory response to anaemia was an increase in cardiac output.
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Affiliation(s)
- D K Gold
- Department of Zoology and The Faculty of Land and Food Systems, University of British Columbia, 6270 University Blvd., Vancouver, BC, V6T 1Z4, Canada
| | - T Loirat
- Department of Zoology and The Faculty of Land and Food Systems, University of British Columbia, 6270 University Blvd., Vancouver, BC, V6T 1Z4, Canada
| | - A P Farrell
- Department of Zoology and The Faculty of Land and Food Systems, University of British Columbia, 6270 University Blvd., Vancouver, BC, V6T 1Z4, Canada
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Elasmobranch Cardiovascular System. ACTA ACUST UNITED AC 2015. [DOI: 10.1016/b978-0-12-801286-4.00001-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Brijs J, Jutfelt F, Clark TD, Gräns A, Ekström A, Sandblom E. Experimental manipulations of tissue oxygen supply do not affect warming tolerance of European perch. J Exp Biol 2015; 218:2448-54. [DOI: 10.1242/jeb.121889] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 05/21/2015] [Indexed: 01/18/2023]
Abstract
A progressive inability of the cardiorespiratory system to maintain systemic oxygen supply at elevated temperatures has been suggested to reduce aerobic scope and the upper thermal limit of aquatic ectotherms. However, few studies have directly investigated the dependence of thermal limits on oxygen transport capacity. By manipulating oxygen availability (via environmental hyperoxia) and blood oxygen carrying capacity (via experimentally-induced anemia) in European perch (Perca fluviatilis, Linneaus), we investigated the effects of oxygen transport capacity on aerobic scope and the critical thermal maximum (CTmax). Hyperoxia resulted in a two-fold increase in aerobic scope at the control temperature of 23°C, but this did not translate to an elevated CTmax in comparison with control fish (34.6±0.1°C vs. 34.0±0.5°C, respectively). Anemia (∼43% reduction in haemoglobin concentration) did not cause a reduction in aerobic scope nor CTmax (33.8±0.3°C) compared with control fish. Additionally, oxygen consumption rates of anemic perch during thermal ramping increased in a similar exponential manner as in control fish, highlighting that perch have an impressive capacity to compensate for a substantial reduction in blood oxygen carrying capacity. Taken together, these results indicate that oxygen limitation is not a universal mechanism determining the CTmax of fishes.
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Affiliation(s)
- Jeroen Brijs
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Fredrik Jutfelt
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Timothy D. Clark
- University of Tasmania and CSIRO Agriculture Flagship, Hobart, Tasmania, Australia (formerly at the Australian Institute of Marine Science, Townsville, Queensland Australia)
| | - Albin Gräns
- Department of Animal Environment and Health, Swedish University of Agricultural Sciences, Skara, Sweden
| | - Andreas Ekström
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Erik Sandblom
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
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