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Kraskura K, Hardison EA, Eliason EJ. Body size and temperature affect metabolic and cardiac thermal tolerance in fish. Sci Rep 2023; 13:17900. [PMID: 37857749 PMCID: PMC10587238 DOI: 10.1038/s41598-023-44574-w] [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: 01/20/2023] [Accepted: 10/10/2023] [Indexed: 10/21/2023] Open
Abstract
Environmental warming is associated with reductions in ectotherm body sizes, suggesting that larger individuals may be more vulnerable to climate change. The mechanisms driving size-specific vulnerability to temperature are unknown but are required to finetune predictions of fisheries productivity and size-structure community responses to climate change. We explored the potential metabolic and cardiac mechanisms underlying these body size vulnerability trends in a eurythermal fish, barred surfperch. We acutely exposed surfperch across a large size range (5-700 g) to four ecologically relevant temperatures (16 °C, 12 °C, 20 °C, and 22 °C) and subsequently, measured their metabolic capacity (absolute and factorial aerobic scopes, maximum and resting metabolic rates; AAS, FAS, MMR, RMR). Additionally, we estimated the fish's cardiac thermal tolerance by measuring their maximum heart rates (fHmax) across acutely increasing temperatures. Barred surfperch had parallel hypoallometric scaling of MMR and RMR (exponent 0.81) and a weaker hypoallometric scaling of fHmax (exponent - 0.05) across all test temperatures. In contrast to our predictions, the fish's aerobic capacity was maintained across sizes and acute temperatures, and larger fish had greater cardiac thermal tolerance than smaller fish. These results demonstrate that thermal performance may be limited by different physiological constraints depending on the size of the animal and species of interest.
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Affiliation(s)
- Krista Kraskura
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA, 93106, USA.
| | - Emily A Hardison
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA, 93106, USA
| | - Erika J Eliason
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA, 93106, USA
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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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Wheeler CR, Lang BJ, Mandelman JW, Rummer JL. The upper thermal limit of epaulette sharks ( Hemiscyllium ocellatum) is conserved across three life history stages, sex and body size. CONSERVATION PHYSIOLOGY 2022; 10:coac074. [PMID: 36583221 PMCID: PMC9795165 DOI: 10.1093/conphys/coac074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 10/17/2022] [Accepted: 11/13/2022] [Indexed: 06/17/2023]
Abstract
Owing to climate change, most notably the increasing frequency of marine heatwaves and long-term ocean warming, better elucidating the upper thermal limits of marine fishes is important for predicting the future of species and populations. The critical thermal maximum (CTmax), or the highest temperature a species can tolerate, is a physiological metric that is used to establish upper thermal limits. Among marine organisms, this metric is commonly assessed in bony fishes but less so in other taxonomic groups, such as elasmobranchs (subclass of sharks, rays and skates), where only thermal acclimation effects on CTmax have been assessed. Herein, we tested whether three life history stages, sex and body size affected CTmax in a tropical elasmobranch, the epaulette shark (Hemiscyllium ocellatum), collected from the reef flats surrounding Heron Island, Australia. Overall, we found no difference in CTmax between life history stages, sexes or across a range of body sizes. Findings from this research suggest that the energetically costly processes (i.e. growth, maturation and reproduction) associated with the life history stages occupying these tropical reef flats do not change overall acute thermal tolerance. However, it is important to note that neither embryos developing in ovo, neonates, nor females actively encapsulating egg cases were observed in or collected from the reef flats. Overall, our findings provide the first evidence in an elasmobranch that upper thermal tolerance is not impacted by life history stage or size. This information will help to improve our understanding of how anthropogenic climate change may (or may not) disproportionally affect particular life stages and, as such, where additional conservation and management actions may be required.
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Affiliation(s)
- Carolyn R Wheeler
- Corresponding author: 1 James Cook Drive, Douglas, Queensland 4814, Australia. Tel: + 61 0480 129 737.
| | - Bethan J Lang
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland 4814, Australia
| | - John W Mandelman
- School for the Environment, The University of Massachusetts Boston, Boston, MA 02125, USA
- Anderson Cabot Center for Ocean Life, New England Aquarium, Boston, MA 02110, USA
| | - Jodie L Rummer
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland 4814, Australia
- College of Science and Engineering, James Cook University, Townsville, Queensland 4814, Australia
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Abstract
AbstractThe identification of biological pattern is often complicated by the lack of methodologically consistent data with broad geographic coverage, especially when considering functional characteristics of organisms that differ greatly in body size and morphology. In our study (Dahlke et al. 2020), we addressed the problem of data scarcity by using different types of observational and experimental data together with statistical (phylogenetic) data imputation, and by placing our analysis into the context of a physiological concept, which provides a mechanism-based explanation for the observed pattern (ontogenetic shift in thermal tolerance of fish) and with respect to transition from sublethal to lethal thresholds. Here, we show with comparative examples that our results were not affected by the use of methodologically inconsistent data.
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