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Horne LM, DeVries DR, Wright R, Irwin E, Staton BA, Abdelrahman HA, Stoeckel JA. Thermal performance of the electron transport system Complex III in seven Alabama fishes. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2023; 339:153-162. [PMID: 36285344 DOI: 10.1002/jez.2667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Revised: 07/13/2022] [Accepted: 09/23/2022] [Indexed: 11/06/2022]
Abstract
Management of fish populations for conservation in thermally variable systems requires an understanding of the fish's underlying physiology and responses to thermal stress. Physiological research at the organismal level provides information on the overall effects of stressors such as extreme temperature fluctuations. While experiments with whole organisms provide information as to the overall effects of temperature fluctuations, biochemical assays of thermal stress provide direct results of exposure that are both sensitive and specific. Electron transport system (ETS; Complex III) assays quantify a rate-limiting step of respiratory enzymes. Parameters that can be estimated via this approach include optimum thermal temperature (Topt ) and optimal breadth of thermal performance (Tbreadth ), which can both be related to organismal-level temperature thresholds. We exposed enzymes of seven fish species (native fish chosen to represent a typical community in Alabama streams) to temperatures in the range 11-44°C. The resultant enzymatic thermal performance curves showed that Topt , the lower temperature for enzyme optimal thermal performance (Tlow ), the upper temperature for enzyme optimal thermal performance (Tup ), and Tbreadth differed among species. Relationships between enzymatic activity and temperature for all fish followed a pattern of steadily increasing enzyme activity to Topt before gradually decreasing with increasing temperature. A comparison of our enzyme optimum and upper-temperature limit results versus published critical thermal maxima values supports that ETS Complex III assays may be useful for assessing organismal-level thermal tolerance.
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Affiliation(s)
- Lindsay M Horne
- School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, Auburn, Alabama, USA.,Department of Biology, School of Mathematics and Sciences, Lincoln Memorial University, Tennessee, Harrogate, USA
| | - Dennis R DeVries
- School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, Auburn, Alabama, USA
| | - Russell Wright
- School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, Auburn, Alabama, USA
| | - Elise Irwin
- U.S. Geological Survey, Cooperative Fish and Wildlife Research Units, Auburn, Alabama, USA
| | | | - Hisham A Abdelrahman
- School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, Auburn, Alabama, USA.,Department of Veterinary Hygiene and Management, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt
| | - James A Stoeckel
- School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, Auburn, Alabama, USA
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Jager HI, Long JW, Malison RL, Murphy BP, Rust A, Silva LGM, Sollmann R, Steel ZL, Bowen MD, Dunham JB, Ebersole JL, Flitcroft RL. Resilience of terrestrial and aquatic fauna to historical and future wildfire regimes in western North America. Ecol Evol 2021; 11:12259-12284. [PMID: 34594498 PMCID: PMC8462151 DOI: 10.1002/ece3.8026] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 07/12/2021] [Accepted: 07/24/2021] [Indexed: 01/08/2023] Open
Abstract
Wildfires in many western North American forests are becoming more frequent, larger, and severe, with changed seasonal patterns. In response, coniferous forest ecosystems will transition toward dominance by fire-adapted hardwoods, shrubs, meadows, and grasslands, which may benefit some faunal communities, but not others. We describe factors that limit and promote faunal resilience to shifting wildfire regimes for terrestrial and aquatic ecosystems. We highlight the potential value of interspersed nonforest patches to terrestrial wildlife. Similarly, we review watershed thresholds and factors that control the resilience of aquatic ecosystems to wildfire, mediated by thermal changes and chemical, debris, and sediment loadings. We present a 2-dimensional life history framework to describe temporal and spatial life history traits that species use to resist wildfire effects or to recover after wildfire disturbance at a metapopulation scale. The role of fire refuge is explored for metapopulations of species. In aquatic systems, recovery of assemblages postfire may be faster for smaller fires where unburned tributary basins or instream structures provide refuge from debris and sediment flows. We envision that more-frequent, lower-severity fires will favor opportunistic species and that less-frequent high-severity fires will favor better competitors. Along the spatial dimension, we hypothesize that fire regimes that are predictable and generate burned patches in close proximity to refuge will favor species that move to refuges and later recolonize, whereas fire regimes that tend to generate less-severely burned patches may favor species that shelter in place. Looking beyond the trees to forest fauna, we consider mitigation options to enhance resilience and buy time for species facing a no-analog future.
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Affiliation(s)
- Henriette I. Jager
- Environmental Sciences DivisionOak Ridge National Laboratory (ORNL)Oak RidgeTNUSA
| | - Jonathan W. Long
- U.S. Department of AgriculturePacific Southwest Research StationDavisCAUSA
| | - Rachel L. Malison
- Flathead Lake Biological StationThe University of MontanaPolsonMTUSA
| | - Brendan P. Murphy
- School of Environmental ScienceSimon Fraser UniversityBurnabyBCCanada
| | - Ashley Rust
- Civil and Environmental Engineering DepartmentColorado School of MinesGoldenCOUSA
| | - Luiz G. M. Silva
- Institute for Land, Water and SocietyCharles Sturt UniversityAlburyNSWAustralia
- Department of CivilEnvironmental and Geomatic EngineeringStocker LabInstitute of Environmental EngineeringETH ZurichZürichSwitzerland
| | - Rahel Sollmann
- Department of Wildlife, Fish, and Conservation BiologyUniversity of California DavisDavisCAUSA
| | - Zachary L. Steel
- Department of Environmental Science, Policy and ManagementUniversity of CaliforniaBerkeleyCAUSA
| | - Mark D. Bowen
- Thomas Gast & Associates Environmental ConsultantsArcataCAUSA
| | - Jason B. Dunham
- U.S. Geological Survey, Forest and Rangeland Ecosystem Science CenterCorvallisORUSA
| | - Joseph L. Ebersole
- Center for Public Health and Environmental AssessmentPacific Ecological Systems DivisionU.S. Environmental Protection AgencyCorvallisORUSA
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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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