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Sandrelli RM, Gamperl AK. The upper temperature and hypoxia limits of Atlantic salmon (Salmo salar) depend greatly on the method utilized. J Exp Biol 2023; 226:jeb246227. [PMID: 37622446 PMCID: PMC10560559 DOI: 10.1242/jeb.246227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 08/17/2023] [Indexed: 08/26/2023]
Abstract
In this study, Atlantic salmon were: (i) implanted with heart rate (fH) data storage tags (DSTs), pharmacologically stimulated to maximum fH, and warmed at 10°C h-1 (i.e. tested using a 'rapid screening protocol'); (ii) fitted with Doppler® flow probes, recovered in respirometers and given a critical thermal maximum (CTmax) test at 2°C h-1; and (iii) implanted with fH DSTs, recovered in a tank with conspecifics for 4 weeks, and had their CTmax determined at 2°C h-1. Fish in respirometers and those free-swimming were also exposed to a stepwise decrease in water oxygen level (100% to 30% air saturation) to determine the oxygen level at which bradycardia occurred. Resting fH was much lower in free-swimming fish than in those in respirometers (∼49 versus 69 beats min-1) and this was reflected in their scope for fH (∼104 versus 71 beats min-1) and CTmax (27.7 versus 25.9°C). Further, the Arrhenius breakpoint temperature and temperature at peak fH for free-swimming fish were considerably greater than for those tested in the respirometers and given a rapid screening protocol (18.4, 18.1 and 14.6°C; and 26.5, 23.2 and 20.2°C, respectively). Finally, the oxygen level at which bradycardia occurred was significantly higher in free-swimming salmon than in those in respirometers (∼62% versus 53% air saturation). These results: highlight the limitations of some lab-based methods of determining fH parameters and thermal tolerance in fishes; and suggest that scope for fH may be a more reliable and predictive measure of a fish's upper thermal tolerance than their peak fH.
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Affiliation(s)
- Rebeccah M. Sandrelli
- Department of Ocean Sciences, Memorial University of Newfoundland and Labrador, St John's, NL, Canada, A1C 5S7
| | - A. Kurt Gamperl
- Department of Ocean Sciences, Memorial University of Newfoundland and Labrador, St John's, NL, Canada, A1C 5S7
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2
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Desforges JE, Birnie-Gauvin K, Jutfelt F, Gilmour KM, Eliason EJ, Dressler TL, McKenzie DJ, Bates AE, Lawrence MJ, Fangue N, Cooke SJ. The ecological relevance of critical thermal maxima methodology for fishes. JOURNAL OF FISH BIOLOGY 2023; 102:1000-1016. [PMID: 36880500 DOI: 10.1111/jfb.15368] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 02/28/2023] [Indexed: 05/13/2023]
Abstract
Critical thermal maxima methodology (CTM) has been used to infer acute upper thermal tolerance in fishes since the 1950s, yet its ecological relevance remains debated. In this study, the authors synthesize evidence to identify methodological concerns and common misconceptions that have limited the interpretation of critical thermal maximum (CTmax ; value for an individual fish during one trial) in ecological and evolutionary studies of fishes. They identified limitations of, and opportunities for, using CTmax as a metric in experiments, focusing on rates of thermal ramping, acclimation regimes, thermal safety margins, methodological endpoints, links to performance traits and repeatability. Care must be taken when interpreting CTM in ecological contexts, because the protocol was originally designed for ecotoxicological research with standardized methods to facilitate comparisons within study individuals, across species and contexts. CTM can, however, be used in ecological contexts to predict impacts of environmental warming, but only if parameters influencing thermal limits, such as acclimation temperature or rate of thermal ramping, are taken into account. Applications can include mitigating the effects of climate change, informing infrastructure planning or modelling species distribution, adaptation and/or performance in response to climate-related temperature change. The authors' synthesis points to several key directions for future research that will further aid the application and interpretation of CTM data in ecological contexts.
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Affiliation(s)
- Jessica E Desforges
- Department of Biology and Institute of Environmental and Interdisciplinary Science, Carleton University, Ottawa, Ontario, Canada
| | - Kim Birnie-Gauvin
- Department of Ecology, Evolution & Marine Biology, University of California Santa Barbara, Santa Barbara, California, USA
- Section for Freshwater Fisheries and Ecology, National Institute of Aquatic Resources, Technical University of Denmark, Silkeborg, Denmark
| | - Fredrik Jutfelt
- Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
| | | | - Erika J Eliason
- Section for Freshwater Fisheries and Ecology, National Institute of Aquatic Resources, Technical University of Denmark, Silkeborg, Denmark
| | - Terra L Dressler
- Section for Freshwater Fisheries and Ecology, National Institute of Aquatic Resources, Technical University of Denmark, Silkeborg, Denmark
| | | | - Amanda E Bates
- Department of Biology, University of Victoria, Victoria, British Columbia, Canada
| | - Michael J Lawrence
- Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Nann Fangue
- Department of Wildlife, Fish, and Conservation Biology, University of California Davis, Davis, California, USA
| | - Steven J Cooke
- Department of Biology and Institute of Environmental and Interdisciplinary Science, Carleton University, Ottawa, Ontario, Canada
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3
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Ørsted M, Jørgensen LB, Overgaard J. Finding the right thermal limit: a framework to reconcile ecological, physiological and methodological aspects of CTmax in ectotherms. J Exp Biol 2022; 225:277015. [DOI: 10.1242/jeb.244514] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
ABSTRACT
Upper thermal limits (CTmax) are frequently used to parameterize the fundamental niche of ectothermic animals and to infer biogeographical distribution limits under current and future climate scenarios. However, there is considerable debate associated with the methodological, ecological and physiological definitions of CTmax. The recent (re)introduction of the thermal death time (TDT) model has reconciled some of these issues and now offers a solid mathematical foundation to model CTmax by considering both intensity and duration of thermal stress. Nevertheless, the physiological origin and boundaries of this temperature–duration model remain unexplored. Supported by empirical data, we here outline a reconciling framework that integrates the TDT model, which operates at stressful temperatures, with the classic thermal performance curve (TPC) that typically describes biological functions at permissive temperatures. Further, we discuss how the TDT model is founded on a balance between disruptive and regenerative biological processes that ultimately defines a critical boundary temperature (Tc) separating the TDT and TPC models. Collectively, this framework allows inclusion of both repair and accumulation of heat stress, and therefore also offers a consistent conceptual approach to understand the impact of high temperature under fluctuating thermal conditions. Further, this reconciling framework allows improved experimental designs to understand the physiological underpinnings and ecological consequences of ectotherm heat tolerance.
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Affiliation(s)
- Michael Ørsted
- Aarhus University Section for Zoophysiology, Department of Biology , , 8000 Aarhus C , Denmark
| | | | - Johannes Overgaard
- Aarhus University Section for Zoophysiology, Department of Biology , , 8000 Aarhus C , Denmark
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4
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Brain dysfunction during warming is linked to oxygen limitation in larval zebrafish. Proc Natl Acad Sci U S A 2022; 119:e2207052119. [PMID: 36122217 PMCID: PMC9522358 DOI: 10.1073/pnas.2207052119] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Understanding the physiological mechanisms that limit animal thermal tolerance is crucial in predicting how animals will respond to increasingly severe heat waves. Despite their importance for understanding climate change impacts, these mechanisms underlying the upper thermal tolerance limits of animals are largely unknown. It has been hypothesized that the upper thermal tolerance in fish is limited by the thermal tolerance of the brain and is ultimately caused by a global brain depolarization. In this study, we developed methods for measuring the upper thermal limit (CTmax) in larval zebrafish (Danio rerio) with simultaneous recordings of brain activity using GCaMP6s calcium imaging in both free-swimming and agar-embedded fish. We discovered that during warming, CTmax precedes, and is therefore not caused by, a global brain depolarization. Instead, the CTmax coincides with a decline in spontaneous neural activity and a loss of neural response to visual stimuli. By manipulating water oxygen levels both up and down, we found that oxygen availability during heating affects locomotor-related neural activity, the neural response to visual stimuli, and CTmax. Our results suggest that the mechanism limiting the upper thermal tolerance in zebrafish larvae is insufficient oxygen availability causing impaired brain function.
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5
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Blasco FR, Taylor EW, Leite CAC, Monteiro DA, Rantin FT, McKenzie DJ. Tolerance of an acute warming challenge declines with body mass in Nile tilapia: evidence of a link to capacity for oxygen uptake. J Exp Biol 2022; 225:276171. [PMID: 35909333 DOI: 10.1242/jeb.244287] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 07/25/2022] [Indexed: 11/20/2022]
Abstract
It has been proposed that larger individuals within fish species may be more sensitive to global warming, due to limitations in their capacity to provide oxygen for aerobic metabolic activities. This could affect size distributions of populations in a warmer world but evidence is lacking. In Nile tilapia Oreochromis niloticus (n=18, mass range 21 - 313g), capacity to provide oxygen for aerobic activities (aerobic scope) was independent of mass at an acclimation temperature of 26 °C. Tolerance of acute warming, however, declined significantly with mass when evaluated as the critical temperature for fatigue from aerobic swimming (CTSmax). The CTSmax protocol challenges a fish to meet the oxygen demands of constant aerobic exercise while their demands for basal metabolism are accelerated by incremental warming, culminating in fatigue. CTSmax elicited pronounced increases in oxygen uptake in the tilapia but the maximum rates achieved prior to fatigue declined very significantly with mass. Mass-related variation in CTSmax and maximum oxygen uptake rates were positively correlated, which may indicate a causal relationship. When fish populations are faced with acute thermal stress, larger individuals may become constrained in their ability to perform aerobic activities at lower temperatures than smaller conspecifics. This could affect survival and fitness of larger fish in a future world with more frequent and extreme heatwaves, with consequences for population productivity.
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Affiliation(s)
- F R Blasco
- Department of Physiological Sciences, Federal University of São Carlos, 13565-905, São Carlos (SP), Brazil.,Joint Graduate Program in Physiological Sciences, Federal University of São Carlos - UFSCar/São Paulo State University, UNESP Campus Araraquara, 14801-903, Araraquara SP, Brazil
| | - E W Taylor
- Department of Physiological Sciences, Federal University of São Carlos, 13565-905, São Carlos (SP), Brazil.,School of Biosciences, University of Birmingham, B15 2TT, UK
| | - C A C Leite
- Department of Physiological Sciences, Federal University of São Carlos, 13565-905, São Carlos (SP), Brazil
| | - D A Monteiro
- Department of Physiological Sciences, Federal University of São Carlos, 13565-905, São Carlos (SP), Brazil
| | - F T Rantin
- Department of Physiological Sciences, Federal University of São Carlos, 13565-905, São Carlos (SP), Brazil
| | - D J McKenzie
- Department of Physiological Sciences, Federal University of São Carlos, 13565-905, São Carlos (SP), Brazil.,MARBEC, Université Montpellier, CNRS, Ifremer, IRD, 34095 Montpellier, France
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6
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Acute critical thermal maximum does not predict chronic incremental thermal maximum in Atlantic salmon (Salmo salar). Comp Biochem Physiol A Mol Integr Physiol 2022; 266:111143. [PMID: 34995773 DOI: 10.1016/j.cbpa.2022.111143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Revised: 12/31/2021] [Accepted: 12/31/2021] [Indexed: 10/19/2022]
Abstract
Atlantic salmon is an important aquaculture species farmed in ocean net-pens and therefore subjected to changing environmental conditions, including rising temperatures. This creates a need for research on the thermal tolerance of this species for the future of sustainable aquaculture. We investigated the thermal tolerance of individually tagged Atlantic salmon post-smolts subjected sequentially to two common high-temperature challenges: critical thermal maximum (CTmax) followed by incremental thermal maximum (ITmax). Our goals were (1) to determine whether CTmax can predict ITmax for individual fish, and (2) to examine connections between various body size (mass, length, condition factor), cardiac (absolute and relative ventricle mass) and blood (hematocrit) metrics and thermal tolerance. We found no relationship between CTmax and ITmax. This is of concern because CTmax, which is a quick and easy test, is often used to predict upper lethal limits in fish despite not using real-world rates of temperature increase and not using death as the experimental endpoint (unlike ITmax). Also, some metrics which correlated in one direction with CTmax had the opposite correlation with ITmax. For instance, smaller fish or fish with smaller ventricles had a higher CTmax but a lower ITmax than larger fish or fish with larger ventricles. Taken together, these results highlight the need to take care when using acute thermal tolerance tests to predict real-world responses to rising temperatures.
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7
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Monteiro DA, Kalinin AL, Rantin FT, McKenzie DJ. Use of complex physiological traits as ecotoxicological biomarkers in tropical freshwater fishes. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2021; 335:745-760. [PMID: 34529366 DOI: 10.1002/jez.2540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 07/21/2021] [Accepted: 08/02/2021] [Indexed: 06/13/2023]
Abstract
We review the use of complex physiological traits, of tolerance and performance, as biomarkers of the toxicological effects of contaminants in subtropical and tropical freshwater fishes. Such traits are growing in relevance due to climate change, as exposure to contaminants may influence the capacity of fishes to tolerate and perform in an increasingly stressful environment. We review the evidence that the critical oxygen level, a measure of hypoxia tolerance, provides a valuable biomarker of impacts of diverse classes of contaminants. When coupled with measures of cardiorespiratory variables, it can provide insight into mechanisms of toxicity. The critical thermal maximum, a simple measure of tolerance of acute warming, also provides a valuable biomarker despite a lack of understanding of its mechanistic basis. Its relative ease of application renders it useful in the rapid evaluation of multiple species, and in understanding how the severity of contaminant impacts depends upon prevailing environmental temperature. The critical swimming speed is a measure of exercise performance that is widely used as a biomarker in temperate species but very few studies have been performed on subtropical or tropical fishes. Overall, the review serves to highlight a critical lack of knowledge for subtropical and tropical freshwater fishes. There is a real need to expand the knowledge base and to use physiological biomarkers in support of decision making to manage tropical freshwater fish populations and their habitats, which sustain rich biodiversity but are under relentless anthropogenic pressure.
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Affiliation(s)
- Diana A Monteiro
- Department of Physiological Sciences, Federal University of São Carlos (UFSCar), São Carlos, São Paulo, Brazil
| | - Ana L Kalinin
- Department of Physiological Sciences, Federal University of São Carlos (UFSCar), São Carlos, São Paulo, Brazil
| | - F Tadeu Rantin
- Department of Physiological Sciences, Federal University of São Carlos (UFSCar), São Carlos, São Paulo, Brazil
| | - David J McKenzie
- Department of Physiological Sciences, Federal University of São Carlos (UFSCar), São Carlos, São Paulo, Brazil
- UMR Marbec, Univ. Montpellier, CNRS, IRD, Ifremer, Montpellier, France
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8
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Limits of temperature adaptation and thermopreferendum. Cell Biosci 2021; 11:69. [PMID: 33823918 PMCID: PMC8025563 DOI: 10.1186/s13578-021-00574-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 03/18/2021] [Indexed: 11/10/2022] Open
Abstract
Background Managing the limits of temperature adaptation is relevant both in medicine and in biotechnology. There are numerous scattered publications on the identification of the temperature limits of existence for various organisms and using different methods. Dmitry Petrovich Kharakoz gave a general explanation for many of these experimental results. The hypothesis implied that each cycle of synaptic exocytosis includes reversible phase transitions of lipids of the presynaptic membrane due to the entry and subsequent removal of calcium ions from the synaptic terminal. The correspondence of the times of phase transitions has previously been experimentally shown on isolated lipids in vitro. In order to test the hypothesis of D.P. Kharakoz in vivo, we investigated the influence of the temperature of long-term acclimatization on the temperature of heat and cold shock, as well as on the kinetics of temperature adaptation in zebrafish. Testing the hypothesis included a comparison of our experimental results with the results of other authors obtained on various models from invertebrates to humans. Results The viability polygon for Danio rerio was determined by the minimum temperature of cold shock (about 6 °C), maximum temperature of heat shock (about 43 °C), and thermopreferendum temperature (about 27 °C). The ratio of the temperature range of cold shock to the temperature range of heat shock was about 1.3. These parameters obtained for Danio rerio describe with good accuracy those for the planarian Girardia tigrina, the ground squirrel Sermophilus undulatus, and for Homo sapiens. Conclusions The experimental values of the temperatures of cold shock and heat shock and the temperature of the thermal preferendum correspond to the temperatures of phase transitions of the lipid-protein composition of the synaptic membrane between the liquid and solid states. The viability range for zebrafish coincides with the temperature range, over which enzymes function effectively and also coincides with the viability polygons for the vast majority of organisms. The boundaries of the viability polygon are characteristic biological constants. The viability polygon of a particular organism is determined not only by the genome, but also by the physicochemical properties of lipids that make up the membrane structures of synaptic endings. The limits of temperature adaptation of any biological species are determined by the temperature range of the functioning of its nervous system.
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9
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Varying heat tolerance among Arctic nearshore fishes. Polar Biol 2021. [DOI: 10.1007/s00300-021-02815-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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10
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Homeoviscous adaptation occurs with thermal acclimation in biological membranes from heart and gill, but not the brain, in the Antarctic fish Notothenia coriiceps. J Comp Physiol B 2021; 191:289-300. [PMID: 33479792 PMCID: PMC8895410 DOI: 10.1007/s00360-020-01339-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 12/10/2020] [Accepted: 12/30/2020] [Indexed: 02/08/2023]
Abstract
As temperatures continue to rise, adjustments to biological membranes will be key for maintenance of function. It is largely unknown to what extent Antarctic notothenioids possess the capacity to remodel their biological membranes in response to thermal change. In this study, physical and biochemical properties were examined in membranes prepared from gill epithelia (plasma membranes), cardiac ventricles (microsomes, mitochondria), and brains (synaptic membranes, myelin, mitochondria) from Notothenia coriiceps following acclimation to 5 °C (or held at ambient temperature, 0 °C) for a minimum of 6 weeks. Fluidity was measured between 0 and 30 °C in all membranes, and polar lipid compositions and cholesterol contents were analyzed in a subset of biological membranes from all tissues. Osmotic permeability was measured in gills at 0 and 4 °C. Gill plasma membranes, cardiac mitochondria, and cardiac microsomes displayed reduced fluidity following acclimation to 5 °C, indicating compensation for elevated temperature. In contrast, no fluidity changes with acclimation were observed in any of the membranes prepared from brain. In all membranes, adjustments to the relative abundances of major phospholipid classes, and to the extent of fatty acid unsaturation, were undetectable following thermal acclimation. However, alterations in cholesterol contents and acyl chain length, consistent with the changes in fluidity, were observed in membranes from gill and cardiac tissue. Water permeability was reduced with 5 °C acclimation in gills, indicating near-perfect homeostatic efficacy. Taken together, these results demonstrate a homeoviscous response in gill and cardiac membranes, and limited plasticity in membranes from the nervous system, in an Antarctic notothenioid.
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11
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Lefevre S, Wang T, McKenzie DJ. The role of mechanistic physiology in investigating impacts of global warming on fishes. J Exp Biol 2021; 224:224/Suppl_1/jeb238840. [PMID: 33627469 DOI: 10.1242/jeb.238840] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Warming of aquatic environments as a result of climate change is already having measurable impacts on fishes, manifested as changes in phenology, range shifts and reductions in body size. Understanding the physiological mechanisms underlying these seemingly universal patterns is crucial if we are to reliably predict the fate of fish populations with future warming. This includes an understanding of mechanisms for acute thermal tolerance, as extreme heatwaves may be a major driver of observed effects. The hypothesis of gill oxygen limitation (GOL) is claimed to explain asymptotic fish growth, and why some fish species are decreasing in size with warming; but its underlying assumptions conflict with established knowledge and direct mechanistic evidence is lacking. The hypothesis of oxygen- and capacity-limited thermal tolerance (OCLTT) has stimulated a wave of research into the role of oxygen supply capacity and thermal performance curves for aerobic scope, but results vary greatly between species, indicating that it is unlikely to be a universal mechanism. As thermal performance curves remain important for incorporating physiological tolerance into models, we discuss potentially fruitful alternatives to aerobic scope, notably specific dynamic action and growth rate. We consider the limitations of estimating acute thermal tolerance by a single rapid measure whose mechanism of action is not known. We emphasise the continued importance of experimental physiology, particularly in advancing our understanding of underlying mechanisms, but also the challenge of making this knowledge relevant to the more complex reality.
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Affiliation(s)
- Sjannie Lefevre
- Section for Physiology and Cell Biology, Department of Biosciences, University of Oslo, 0316 Oslo, Norway
| | - Tobias Wang
- Department of Biology - Zoophysiology, Aarhus University, 8000 Aarhus C, Denmark
| | - David J McKenzie
- Marine Biodiversity, Exploitation and Conservation (MARBEC), Université de Montpellier, CNRS, Ifremer, IRD, 34000 Montpellier, France
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12
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Morgan R, Finnøen MH, Jensen H, Pélabon C, Jutfelt F. Low potential for evolutionary rescue from climate change in a tropical fish. Proc Natl Acad Sci U S A 2020; 117:33365-33372. [PMID: 33318195 PMCID: PMC7776906 DOI: 10.1073/pnas.2011419117] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Climate change is increasing global temperatures and intensifying the frequency and severity of extreme heat waves. How organisms will cope with these changes depends on their inherent thermal tolerance, acclimation capacity, and ability for evolutionary adaptation. Yet, the potential for adaptation of upper thermal tolerance in vertebrates is largely unknown. We artificially selected offspring from wild-caught zebrafish (Danio rerio) to increase (Up-selected) or decrease (Down-selected) upper thermal tolerance over six generations. Selection to increase upper thermal tolerance was also performed on warm-acclimated fish to test whether plasticity in the form of inducible warm tolerance also evolved. Upper thermal tolerance responded to selection in the predicted directions. However, compared to the control lines, the response was stronger in the Down-selected than in the Up-selected lines in which evolution toward higher upper thermal tolerance was slow (0.04 ± 0.008 °C per generation). Furthermore, the scope for plasticity resulting from warm acclimation decreased in the Up-selected lines. These results suggest the existence of a hard limit in upper thermal tolerance. Considering the rate at which global temperatures are increasing, the observed rates of adaptation and the possible hard limit in upper thermal tolerance suggest a low potential for evolutionary rescue in tropical fish living at the edge of their thermal limits.
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Affiliation(s)
- Rachael Morgan
- Department of Biology, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway;
| | - Mette H Finnøen
- Department of Biology, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Henrik Jensen
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Christophe Pélabon
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Fredrik Jutfelt
- Department of Biology, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
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13
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Jung EH, Brix KV, Richards JG, Val AL, Brauner CJ. Reduced hypoxia tolerance and survival at elevated temperatures may limit the ability of Amazonian fishes to survive in a warming world. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 748:141349. [PMID: 32818889 DOI: 10.1016/j.scitotenv.2020.141349] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 07/10/2020] [Accepted: 07/27/2020] [Indexed: 06/11/2023]
Abstract
The Amazon basin contains more than 20% of the world's freshwater fishes, many of ecological and economical importance. An increase in temperature of 2.2 to 7 °C is predicted to occur within the next century in the worst-case scenario of climate change predictions, which will likely be associated with an increase in the prevalence and duration of reduced water oxygen levels (hypoxia). Furthermore, there is an increasing frequency of heat waves in the Amazon basin, which exacerbates issues related to temperature and hypoxia. Increases in temperature and hypoxia both constrain an organism's ability to supply oxygen to metabolizing tissues, thus the ability to cope with thermal and hypoxic stress may be correlated. Here, we reveal a positive correlation between acute thermal tolerance and acute hypoxia tolerance amongst 37 Amazonian fish species at the current river temperatures of 28-31 °C. The effects of long-term (10 days or 4 weeks) increases in temperature were investigated in a subset of 13 species and demonstrated that 2 species failed to acclimate and survive at 33 °C, 9 species failed at 35 °C, and only 2 species survived up to 35 °C. Of those that survived long-term exposure to 33 or 35 °C, the majority of the species demonstrated only an improvement in acute thermal tolerance. In contrast, hypoxia tolerance was reduced following acute- and long-term exposure to 33, 35 or 37 °C in all species investigated. The results of this study suggest that many of the fish species that inhabit the Amazon may be at risk during both short- and long-term temperature increases and these risks are exacerbated by the associated environmental hypoxia.
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Affiliation(s)
- Ellen H Jung
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada.
| | | | - Jeffrey G Richards
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada.
| | | | - Colin J Brauner
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada.
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14
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Åsheim ER, Andreassen AH, Morgan R, Jutfelt F. Rapid-warming tolerance correlates with tolerance to slow warming but not growth at non-optimal temperatures in zebrafish. J Exp Biol 2020; 223:jeb229195. [PMID: 33071218 DOI: 10.1242/jeb.229195] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 10/12/2020] [Indexed: 12/16/2022]
Abstract
Global warming is predicted to increase both acute and prolonged thermal challenges for aquatic ectotherms. Severe short- and medium-term thermal stress over hours to days may cause mortality, while longer sub-lethal thermal challenges may cause performance declines. The inter-relationship between the responses to short, medium and longer thermal challenges is unresolved. We asked if the same individuals are tolerant to both rapid and slow warming challenges, a question that has so far received little attention. Additionally, we investigated the possibility of a thermal syndrome where individuals in a population are distributed along a warm-type to cold-type axis. We tested whether different thermal traits correlate across individuals by acclimating 200 juvenile zebrafish (Danio rerio) to sub- or supra-optimal temperatures for growth (22 and 34°C) for 40 days and measuring growth and thermal tolerance at two different warming rates. We found that tolerance to rapid warming correlated with tolerance to slow warming in the 22°C treatment. However, individual tolerance to neither rapid nor slow warming correlated with growth at the supra-optimal temperature. We thus find some support for a syndrome-like organisation of thermal traits, but the lack of connection between tolerance and growth performance indicates a restricted generality of a thermal syndrome. The results suggest that tolerance to rapid warming may share underlying physiological mechanisms with tolerance to slower heating, and indicate that the relevance of acute critical thermal tolerance extends beyond the rapid ramping rates used to measure them.
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Affiliation(s)
- Eirik R Åsheim
- Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
- Organismal and Evolutionary Biology Research Programme, Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
| | - Anna H Andreassen
- Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Rachael Morgan
- Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Fredrik Jutfelt
- Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
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15
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Little AG, Loughland I, Seebacher F. What do warming waters mean for fish physiology and fisheries? JOURNAL OF FISH BIOLOGY 2020; 97:328-340. [PMID: 32441327 DOI: 10.1111/jfb.14402] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 04/30/2020] [Accepted: 05/20/2020] [Indexed: 06/11/2023]
Abstract
Environmental signals act primarily on physiological systems, which then influence higher-level functions such as movement patterns and population dynamics. Increases in average temperature and temperature variability associated with global climate change are likely to have strong effects on fish physiology and thereby on populations and fisheries. Here we review the principal mechanisms that transduce temperature signals and the physiological responses to those signals in fish. Temperature has a direct, thermodynamic effect on biochemical reaction rates. Nonetheless, plastic responses to longer-term thermal signals mean that fishes can modulate their acute thermal responses to compensate at least partially for thermodynamic effects. Energetics are particularly relevant for growth and movement, and therefore for fisheries, and temperature can have pronounced effects on energy metabolism. All energy (ATP) production is ultimately linked to mitochondria, and temperature has pronounced effects on mitochondrial efficiency and maximal capacities. Mitochondria are dependent on oxygen as the ultimate electron acceptor so that cardiovascular function and oxygen delivery link environmental inputs with energy metabolism. Growth efficiency, that is the conversion of food into tissue, changes with temperature, and there are indications that warmer water leads to decreased conversion efficiencies. Moreover, movement and migration of fish relies on muscle function, which is partially dependent on ATP production but also on intracellular calcium cycling within the myocyte. Neuroendocrine processes link environmental signals to regulated responses at the level of different tissues, including muscle. These physiological processes within individuals can scale up to population responses to climate change. A mechanistic understanding of thermal responses is essential to predict the vulnerability of species and populations to climate change.
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Affiliation(s)
| | - Isabella Loughland
- School of Life and Environmental Sciences A08, University of Sydney, Sydney, Australia
| | - Frank Seebacher
- School of Life and Environmental Sciences A08, University of Sydney, Sydney, Australia
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16
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Jørgensen LB, Robertson RM, Overgaard J. Neural dysfunction correlates with heat coma and CT max in Drosophila but does not set the boundaries for heat stress survival. J Exp Biol 2020; 223:jeb218750. [PMID: 32434804 DOI: 10.1242/jeb.218750] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 05/14/2020] [Indexed: 12/25/2022]
Abstract
When heated, insects lose coordinated movement followed by the onset of heat coma (critical thermal maximum, CTmax). These traits are popular measures to quantify interspecific and intraspecific differences in insect heat tolerance, and CTmax correlates well with current species distributions of insects, including Drosophila Here, we examined the function of the central nervous system (CNS) in five species of Drosophila with different heat tolerances, while they were exposed to either constant high temperature or a gradually increasing temperature (ramp). Tolerant species were able to preserve CNS function at higher temperatures and for longer durations than sensitive species, and similar differences were found for the behavioural indices (loss of coordination and onset of heat coma). Furthermore, the timing and temperature (constant and ramp exposure, respectively) for loss of coordination or complete coma coincided with the occurrence of spreading depolarisation (SD) events in the CNS. These SD events disrupt neurological function and silence the CNS, suggesting that CNS failure is the primary cause of impaired coordination and heat coma. Heat mortality occurs soon after heat coma in insects; to examine whether CNS failure could also be the proximal cause of heat death, we used selective heating of the head (CNS) and abdomen (visceral tissues). When comparing the temperature causing 50% mortality (LT50) of each body part versus that of the whole animal, we found that the head was not particularly heat sensitive compared with the abdomen. Accordingly, it is unlikely that nervous failure is the principal/proximate cause of heat mortality in Drosophila.
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Affiliation(s)
- Lisa B Jørgensen
- Zoophysiology, Department of Biology, Aarhus University, 8000 Aarhus C, Denmark
| | | | - Johannes Overgaard
- Zoophysiology, Department of Biology, Aarhus University, 8000 Aarhus C, Denmark
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Blasco FR, Esbaugh AJ, Killen SS, Rantin FT, Taylor EW, McKenzie DJ. Using aerobic exercise to evaluate sub-lethal tolerance of acute warming in fishes. ACTA ACUST UNITED AC 2020; 223:jeb.218602. [PMID: 32381588 PMCID: PMC7225124 DOI: 10.1242/jeb.218602] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 03/01/2020] [Indexed: 01/10/2023]
Abstract
We investigated whether fatigue from sustained aerobic swimming provides a sub-lethal endpoint to define tolerance of acute warming in fishes, as an alternative to loss of equilibrium (LOE) during a critical thermal maximum (CTmax) protocol. Two species were studied, Nile tilapia (Oreochromis niloticus) and pacu (Piaractus mesopotamicus). Each fish underwent an incremental swim test to determine gait transition speed (U GT), where it first engaged the unsteady anaerobic swimming mode that preceded fatigue. After suitable recovery, each fish was exercised at 85% of their own U GT and warmed 1°C every 30 min, to identify the temperature at which they fatigued, denoted as CTswim Fish were also submitted to a standard CTmax, warming at the same rate as CTswim, under static conditions until LOE. All individuals fatigued in CTswim, at a mean temperature approximately 2°C lower than their CTmax Therefore, if exposed to acute warming in the wild, the ability to perform aerobic metabolic work would be constrained at temperatures significantly below those that directly threatened survival. The collapse in performance at CTswim was preceded by a gait transition qualitatively indistinguishable from that during the incremental swim test. This suggests that fatigue in CTswim was linked to an inability to meet the tissue oxygen demands of exercise plus warming. This is consistent with the oxygen and capacity limited thermal tolerance (OCLTT) hypothesis, regarding the mechanism underlying tolerance of warming in fishes. Overall, fatigue at CTswim provides an ecologically relevant sub-lethal threshold that is more sensitive to extreme events than LOE at CTmax.
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Affiliation(s)
- Felipe R Blasco
- Department of Physiological Sciences, Federal University of São Carlos, 13565-905 São Carlos, SP, Brazil .,Joint Graduate Program in Physiological Sciences, Federal University of São Carlos - UFSCar/São Paulo State University, UNESP Campus Araraquara, 14801-903 Araraquara, SP, Brazil
| | - Andrew J Esbaugh
- Marine Science Institute, University of Texas at Austin, Austin, TX 78373, USA
| | - Shaun S Killen
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Francisco Tadeu Rantin
- Department of Physiological Sciences, Federal University of São Carlos, 13565-905 São Carlos, SP, Brazil
| | - Edwin W Taylor
- Department of Physiological Sciences, Federal University of São Carlos, 13565-905 São Carlos, SP, Brazil.,School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK
| | - David J McKenzie
- Department of Physiological Sciences, Federal University of São Carlos, 13565-905 São Carlos, SP, Brazil.,MARBEC, Université de Montpellier, CNRS, Ifremer, IRD, 34000 Montpellier, France
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18
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Illing B, Downie A, Beghin M, Rummer J. Critical thermal maxima of early life stages of three tropical fishes: Effects of rearing temperature and experimental heating rate. J Therm Biol 2020; 90:102582. [DOI: 10.1016/j.jtherbio.2020.102582] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 03/20/2020] [Accepted: 03/31/2020] [Indexed: 01/26/2023]
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Frommel AY, Carless J, Hunt BPV, Brauner CJ. Physiological resilience of pink salmon to naturally occurring ocean acidification. CONSERVATION PHYSIOLOGY 2020; 8:coaa059. [PMID: 32765881 PMCID: PMC7397481 DOI: 10.1093/conphys/coaa059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 06/14/2020] [Indexed: 05/12/2023]
Abstract
Pacific salmon stocks are in decline with climate change named as a contributing factor. The North Pacific coast of British Columbia is characterized by strong temporal and spatial heterogeneity in ocean conditions with upwelling events elevating CO2 levels up to 10-fold those of pre-industrial global averages. Early life stages of pink salmon have been shown to be affected by these CO2 levels, and juveniles naturally migrate through regions of high CO2 during the energetically costly phase of smoltification. To investigate the physiological response of out-migrating wild juvenile pink salmon to these naturally occurring elevated CO2 levels, we captured fish in Georgia Strait, British Columbia and transported them to a marine lab (Hakai Institute, Quadra Island) where fish were exposed to one of three CO2 levels (850, 1500 and 2000 μatm CO2) for 2 weeks. At ½, 1 and 2 weeks of exposure, we measured their weight and length to calculate condition factor (Fulton's K), as well as haematocrit and plasma [Cl-]. At each of these times, two additional stressors were imposed (hypoxia and temperature) to provide further insight into their physiological condition. Juvenile pink salmon were largely robust to elevated CO2 concentrations up to 2000 μatm CO2, with no mortality or change in condition factor over the 2-week exposure duration. After 1 week of exposure, temperature and hypoxia tolerance were significantly reduced in high CO2, an effect that did not persist to 2 weeks of exposure. Haematocrit was increased by 20% after 2 weeks in the CO2 treatments relative to the initial measurements, while plasma [Cl-] was not significantly different. Taken together, these data indicate that juvenile pink salmon are quite resilient to naturally occurring high CO2 levels during their ocean outmigration.
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Affiliation(s)
- Andrea Y Frommel
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
- Corresponding author: Department of Zoology, University of British Columbia, Vancouver, BC, Canada.
| | - Justin Carless
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | - Brian P V Hunt
- Institute for the Oceans and Fisheries, University of British Columbia, Vancouver, BC, Canada
- Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia,, Vancouver, BC, Canada
- Hakai Institute, Quadra Island, BC, Canada
| | - Colin J Brauner
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
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Turko AJ, Nolan CB, Balshine S, Scott GR, Pitcher TE. Thermal tolerance depends on season, age and body condition in imperilled redside dace Clinostomus elongatus. CONSERVATION PHYSIOLOGY 2020; 8:coaa062. [PMID: 32765883 PMCID: PMC7397480 DOI: 10.1093/conphys/coaa062] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 05/30/2020] [Accepted: 06/14/2020] [Indexed: 05/19/2023]
Abstract
Urbanization tends to increase water temperatures in streams and rivers and is hypothesized to be contributing to declines of many freshwater fishes. However, factors that influence individual variation in thermal tolerance, and how these may change seasonally, are not well understood. To address this knowledge gap, we studied redside dace Clinostomus elongatus, an imperilled stream fish native to rapidly urbanizing areas of eastern North America. In wild redside dace from rural Ohio, USA, acute upper thermal tolerance (i.e. critical thermal maximum, CTmax) ranged between ~34°C in summer (stream temperature ~22°C) and 27°C in winter (stream temperature ~2°C). Juveniles had higher CTmax than adults in spring and summer, but in winter, CTmax was higher in adults. Thermal safety margins (CTmax - ambient water temperature; ~11°C) were less than the increases in peak water temperature predicted for many redside dace streams due to the combined effects of climate change and urbanization. Furthermore, behavioural agitation occurred 5-6°C below CTmax. Safety margins were larger (>20°C) in autumn and winter. In addition, redside dace were more sensitive (2.5°C lower CTmax) than southern redbelly dace Chrosomus erythrogaster, a non-imperilled sympatric cyprinid. Body condition (Fulton's K) of adult redside dace was positively correlated with CTmax, but in juveniles, this relationship was significant only in one of two summers of experiments. Next, we measured CTmax of captive redside dace fed experimentally manipulated diets. In adults, but not juveniles, CTmax was higher in fish fed a high- vs. low-ration diet, indicating a causal link between nutrition and thermal tolerance. We conclude that redside dace will be challenged by predicted future summer temperatures, especially in urbanized habitats. Thus, habitat restoration that mitigates temperature increases is likely to benefit redside dace. We also suggest habitat restoration that improves food availability may increase thermal tolerance, and thus population resilience.
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Affiliation(s)
- Andy J Turko
- Great Lakes Institute for Environmental Research, University of Windsor, 2990 Riverside Drive West, Windsor, ON, N9C 1A2, Canada
- Department of Psychology, Neuroscience & Behaviour, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada
- Corresponding author: Great Lakes Institute for Environmental Research, University of Windsor, 2990 Riverside Drive West, Windsor, ON, N9C 1A2, Canada.
| | - Colby B Nolan
- Department of Integrative Biology, University of Windsor, 401 Sunset Avenue, Windsor, ON, N9B 3P4, Canada
| | - Sigal Balshine
- Department of Psychology, Neuroscience & Behaviour, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada
| | - Graham R Scott
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada
| | - Trevor E Pitcher
- Great Lakes Institute for Environmental Research, University of Windsor, 2990 Riverside Drive West, Windsor, ON, N9C 1A2, Canada
- Department of Integrative Biology, University of Windsor, 401 Sunset Avenue, Windsor, ON, N9B 3P4, Canada
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21
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Norin T, Canada P, Bailey JA, Gamperl AK. Thermal biology and swimming performance of Atlantic cod ( Gadus morhua) and haddock ( Melanogrammus aeglefinus). PeerJ 2019; 7:e7784. [PMID: 31592351 PMCID: PMC6777481 DOI: 10.7717/peerj.7784] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Accepted: 08/29/2019] [Indexed: 11/28/2022] Open
Abstract
Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) are two commercially important marine fishes impacted by both overfishing and climate change. Increasing ocean temperatures are affecting the physiology of these species and causing changes in distribution, growth, and maturity. While the physiology of cod has been well investigated, that of haddock has received very little attention. Here, we measured the metabolic response to increasing temperatures, as well as the critical thermal maximum (CTmax), of cod acclimated to 8 and 12 °C and haddock acclimated to 12 °C. We also compared the swimming performance (critical swimming speed, Ucrit) of cod and haddock at 12 °C, as well as the Ucrit of 12 °C-acclimated cod acutely exposed to a higher-than-optimal temperature (16 °C). The CTmax for cod was 21.4 and 23.0 °C for 8- and 12 °C-acclimated fish, respectively, whereas that for the 12 °C-acclimated haddock was 23.9 °C. These values were all significantly different and show that haddock are more tolerant of high temperatures. The aerobic maximum metabolic rate (MMR) of swimming cod remained high at 16 °C, suggesting that maximum oxygen transport capacity was not limited at a temperature above optimal in this species. However, signs of impaired swimming (struggling) were becoming evident at 16 °C. Haddock were found to reach a higher Ucrit than cod at 12 °C (3.02 vs. 2.62 body lengths s−1, respectively), and at a lower MMR. Taken together, these results suggest that haddock perform better than cod in warmer conditions, and that haddock are the superior swimmer amongst the two species.
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Affiliation(s)
- Tommy Norin
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, NL, Canada.,DTU Aqua: National Institute of Aquatic Resources, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Paula Canada
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, NL, Canada.,Oceanic Observatory of Madeira, Agência Regional para o Desenvolvimento da Investigação Tecnologia e Inovação, Funchal, Portugal.,CIIMAR-Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade do Porto, Matosinhos, Portugal
| | - Jason A Bailey
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, NL, Canada.,Vattenbrukscentrum Ost, East Region Aquaculture Centre, Vreta Kloster, Sweden
| | - A Kurt Gamperl
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, NL, Canada
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