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Coffill-Rivera ME, Neal JW, Allen PJ. Effects of temperature on metabolic rate and lower dissolved oxygen tolerance of juvenile speckled peacock bass Cichla temensis. JOURNAL OF FISH BIOLOGY 2023; 102:635-642. [PMID: 36604779 DOI: 10.1111/jfb.15305] [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: 10/12/2022] [Accepted: 01/03/2023] [Indexed: 06/17/2023]
Abstract
The speckled peacock bass Cichla temensis is a popular sport and food fish that generates substantial angling tourism and utilitarian harvest within its range. Its popularity and value make this species important for management and a potential aquaculture candidate for both fisheries enhancement and food fish production. However, little is known of optimal physiochemical conditions in natural habitats, which also are important for the development of hatchery protocols for handling, spawning and grow-out. Speckled peacock bass have been documented to have high sensitivity to extreme temperatures, but the metabolic underpinnings have not been evaluated. In this study, the effects of temperature (25, 30 and 35°C) on the standard metabolic rate (SMR) and lower dissolved oxygen tolerance (LDOT) of juvenile speckled peacock bass (mean ± standard error total length 153 ± 2 mm and wet weight 39.09 ± 1.37 g) were evaluated using intermittent respirometers after an acclimation period of 2 weeks. Speckled peacock bass had the highest SMR at 35°C (345.56 ± 19.89 mgO2 kg-1 h-1 ), followed by 30°C (208.16 ± 12.45 mgO2 kg-1 h-1 ) and 25°C (144.09 ± 10.43 mgO2 kg-1 h-1 ). Correspondingly, the Q10 , or rate of increase in aerobic metabolic rate (MO2 ) relative to 10°C, for 30-35°C was also greater (2.76) than from 25 to 30°C (2.08). Similarly, speckled peacock bass were the most sensitive to hypoxia at the warmest temperature, with an LDOT at pO2 of 90 mmHg (4.13 mg l-1 ) at 35°C compared to pO2 values of 45 mmHg (2.22 mg l-1 ) and 30 mmHg (1.61 mg l-1 ) at 30 and 25°C, respectively. These results indicate that speckled peacock bass are sensitive to temperatures near 35°C, therefore we recommend managing and rearing this species at 25-30°C.
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Affiliation(s)
- Manuel E Coffill-Rivera
- Department of Wildlife, Fisheries and Aquaculture, Mississippi State University, Mississippi State, Mississippi, USA
| | - J Wesley Neal
- Department of Wildlife, Fisheries and Aquaculture, Mississippi State University, Mississippi State, Mississippi, USA
| | - Peter J Allen
- Department of Wildlife, Fisheries and Aquaculture, Mississippi State University, Mississippi State, Mississippi, USA
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2
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Killen SS, Christensen EAF, Cortese D, Závorka L, Norin T, Cotgrove L, Crespel A, Munson A, Nati JJH, Papatheodoulou M, McKenzie DJ. Guidelines for reporting methods to estimate metabolic rates by aquatic intermittent-flow respirometry. J Exp Biol 2021; 224:jeb242522. [PMID: 34520540 PMCID: PMC8467026 DOI: 10.1242/jeb.242522] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Interest in the measurement of metabolic rates is growing rapidly, because of the importance of metabolism in advancing our understanding of organismal physiology, behaviour, evolution and responses to environmental change. The study of metabolism in aquatic animals is undergoing an especially pronounced expansion, with more researchers utilising intermittent-flow respirometry as a research tool than ever before. Aquatic respirometry measures the rate of oxygen uptake as a proxy for metabolic rate, and the intermittent-flow technique has numerous strengths for use with aquatic animals, allowing metabolic rate to be repeatedly estimated on individual animals over several hours or days and during exposure to various conditions or stimuli. There are, however, no published guidelines for the reporting of methodological details when using this method. Here, we provide the first guidelines for reporting intermittent-flow respirometry methods, in the form of a checklist of criteria that we consider to be the minimum required for the interpretation, evaluation and replication of experiments using intermittent-flow respirometry. Furthermore, using a survey of the existing literature, we show that there has been incomplete and inconsistent reporting of methods for intermittent-flow respirometry over the past few decades. Use of the provided checklist of required criteria by researchers when publishing their work should increase consistency of the reporting of methods for studies that use intermittent-flow respirometry. With the steep increase in studies using intermittent-flow respirometry, now is the ideal time to standardise reporting of methods, so that - in the future - data can be properly assessed by other scientists and conservationists.
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Affiliation(s)
- Shaun S. Killen
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - Emil A. F. Christensen
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - Daphne Cortese
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, UK
- PSL Université Paris: EPHE-UPVD-CNRS, USR 3278 CRIOBE, BP 1013, 98729 Papetoai, Moorea, French Polynesia
| | - Libor Závorka
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, UK
- WasserCluster Lunz–Inter-university Centre for Aquatic Ecosystem Research, A-3293 Lunz am See, Austria
| | - Tommy Norin
- DTU Aqua: National Institute of Aquatic Resources, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Lucy Cotgrove
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - Amélie Crespel
- Department of Biology, University of Turku, 20500 Turku, Finland
| | - Amelia Munson
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, UK
- Department of Environmental Science and Policy, University of California, Davis, CA 95615, USA
| | - Julie J. H. Nati
- MARBEC, Université Montpellier, CNRS, Ifremer, IRD, 34000 Montpellier, France
| | - Magdalene Papatheodoulou
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, UK
- Enalia Physis Environmental Research Centre (ENALIA), 2101 Nicosia, Cyprus
| | - David J. McKenzie
- MARBEC, Université Montpellier, CNRS, Ifremer, IRD, 34000 Montpellier, France
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Gomez Isaza DF, Cramp RL, Franklin CE. Exposure to Nitrate Increases Susceptibility to Hypoxia in Fish. Physiol Biochem Zool 2021; 94:124-142. [DOI: 10.1086/713252] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Sánchez-García MA, Zottoli SJ, Roberson LM. Hypoxia Has a Lasting Effect on Fast-Startle Behavior of the Tropical Fish Haemulon plumieri. THE BIOLOGICAL BULLETIN 2019; 237:48-62. [PMID: 31441698 DOI: 10.1086/704337] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Anthropogenic activities and climate change have resulted in an increase of hypoxic conditions in nearshore ecosystems worldwide. Depending on the persistence of a hypoxic event, the survival of aquatic animals can be compromised. Temperate fish exposed to hypoxia display a reduction in the probability of eliciting startle responses thought to be important for escape from predation. Here we examine the effect of hypoxia on the probability of eliciting fast-startle responses (fast-starts) of a tropical fish, the white grunt (Haemulon plumieri), and whether hypoxia has a prolonged impact on behavior once the fish are returned to normoxic conditions. White grunts collected from the San Juan Bay Estuary in Puerto Rico were exposed to an oxygen concentration of 2.5 mg L-1 (40% dissolved oxygen). We found a significant reduction in auditory-evoked fast-starts that lasted for at least 24 hours after fish were returned to normoxic conditions. Accessibility to the neuronal networks that underlie startle responses was an important motivator for this study. Mauthner cells are identifiable neurons found in most fish and amphibians, and these cells are known to initiate fast-starts in teleost fishes. The assumption that most of the short-latency responses in this study are Mauthner cell initiated provided the impetus to characterize the white grunt Mauthner cell. The identification of the cell provides a first step in understanding how low oxygen levels may impact a single cell and its circuit and the behavior it initiates.
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Burggren WW, Mendez-Sanchez JF, Martínez Bautista G, Peña E, Martínez García R, Alvarez González CA. Developmental changes in oxygen consumption and hypoxia tolerance in the heat and hypoxia-adapted tabasco line of the Nile tilapia Oreochromis niloticus, with a survey of the metabolic literature for the genus Oreochromis. JOURNAL OF FISH BIOLOGY 2019; 94:732-744. [PMID: 30847924 DOI: 10.1111/jfb.13945] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2018] [Accepted: 03/01/2019] [Indexed: 06/09/2023]
Abstract
The genus Oreochromis is among the most popular of the tilapiine cichlid tribe for aquaculture. However, their temperature and hypoxia tolerance, if tested at all, is usually tested at temperatures of 20-25°C, rather than at the considerably higher temperatures of 30-35°C typical of tropical aquaculture. We hypothesized that both larvae and adults of the heat and hypoxia-adapted Tabasco-line of the Nile tilapia Oreochromis niloticus would be relatively hypoxia-tolerant. Oxygen consumption rate ( M ˙ O 2 ), Q10 and aquatic surface respiration (ASR) was measured using closed respirometry at 2 (c. 0.2 g), 30 (c. 2-5 g), 105 c. (10-15 g) and 240 (c. 250 g) days of development, at 25°C, 30°C and 35°C. M ˙ O 2 at 30°C was inversely related to body mass: c. 90 μM O2 g-1 /h in larvae down to c. 1 μM O2 g-1 /h in young adults. Q10 for M ˙ O 2 was typical for fish over the range 25-35°C of 1.5-2.0. ASR was exhibited by 50% of the fish at pO2 of 15-50 mmHg in a temperature-dependent fashion. However, the largest adults showed notable ASR only when pO2 fell to below 10 mmHg. Remarkably, pcrit for M ˙ O 2 was 12-17 mmHg at 25-30°C and still only 20-25 mmHg across development at 35°C. These values are among the lowest measured for teleost fishes. Noteworthy is that all fish maintain equilibrium, ventilated their gills and showed routine locomotor action for 10-20 min after M ˙ O 2 ceased at near anoxia and when then returned to oxygenated waters, all fish survived, further indicating a remarkable hypoxic tolerance. Remarkably, data assembled for M ˙ O 2 from >30 studies showed a > x2000 difference, which we attribute to calculation or conversion errors. Nonetheless, pcrit was very low for all Oreochromis sp. and lowest in the heat and hypoxia-adapted Tabasco line.
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Affiliation(s)
- Warren W Burggren
- Developmental Integrative Biology Group, Department of Biology, University of North Texas, Denton, Texas, USA
| | - Jose F Mendez-Sanchez
- Laboratorio de Ecofisiología Animal, Facultad de Ciencias, Universidad Autónoma del Estado de México, Toluca, Mexico
| | - Gil Martínez Bautista
- Laboratorio de Acuicultura Tropical, División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Villahermosa, Mexico
| | - Emyr Peña
- Laboratorio de Acuicultura Tropical, División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Villahermosa, Mexico
| | - Rafael Martínez García
- Laboratorio de Acuicultura Tropical, División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Villahermosa, Mexico
| | - Carlos A Alvarez González
- Laboratorio de Acuicultura Tropical, División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, Villahermosa, Mexico
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Zhang Y, Kieffer JD. The effect of temperature on the resting and post-exercise metabolic rates and aerobic metabolic scope in shortnose sturgeon Acipenser brevirostrum. FISH PHYSIOLOGY AND BIOCHEMISTRY 2017; 43:1245-1252. [PMID: 28405870 DOI: 10.1007/s10695-017-0368-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 03/21/2017] [Indexed: 06/07/2023]
Abstract
The effects of acclimation temperature (15, 20, 25 °C) on routine oxygen consumption and post-exercise maximal oxygen consumption rates (MO2) were measured in juvenile shortnose sturgeon (Acipenser brevirostrum LeSueur, 1818). The routine MO2 of shortnose sturgeon increased significantly from 126.75 mg O2 h-1 kg-1 at 15 °C to 253.13 mg O2 h-1 kg-1 at 25 °C. The temperature coefficient (Q 10) values of the routine metabolic rates ranged between 1.61 and 2.46, with the largest Q 10 values occurring between 15 and 20 °C. The average post-exercise MO2 of all temperature groups increased to a peak value immediately following the exercise, with levels increasing about 2-fold among all temperature groups. The Q 10 values for post-exercise MO2 ranged from 1.21 to 2.12, with the highest difference occurring between 15 and 20 °C. Post-exercise MO2 values of shortnose sturgeon in different temperature groups all decreased exponentially and statistically returned to pre-exercise (resting) levels by 30 min at 15 and 20 °C and by 60 min at 25 °C. The aerobic metabolic scope (post-exercise maximal MO2-routine MO2) increased to a maximum value ∼156 mg O2 h-1 kg-1 at intermediate experimental temperatures (i.e., 20 °C) and then decreased as the temperature increased to 25 °C. However, this trend was not significant. The results suggest that juvenile shortnose sturgeon show flexibility in their ability to adapt to various temperature environments and in their responses to exhaustive exercise.
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Affiliation(s)
- Yueyang Zhang
- Department of Biological Science, University of Alberta, Edmonton, AB, Canada
| | - James D Kieffer
- Department of Biological Sciences & MADSAM Sturgeon Lab, University of New Brunswick, Saint John, NB, Canada.
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Aboagye DL, Allen PJ. Effects of acute and chronic hypoxia on acid–base regulation, hematology, ion, and osmoregulation of juvenile American paddlefish. J Comp Physiol B 2017; 188:77-88. [DOI: 10.1007/s00360-017-1104-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 05/02/2017] [Accepted: 05/07/2017] [Indexed: 11/30/2022]
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8
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Li S, Hafeez A, Noorulla F, Geng X, Shao G, Ren C, Lu G, Zhao H, Ding Y, Ji X. Preconditioning in neuroprotection: From hypoxia to ischemia. Prog Neurobiol 2017; 157:79-91. [PMID: 28110083 DOI: 10.1016/j.pneurobio.2017.01.001] [Citation(s) in RCA: 147] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 01/08/2017] [Accepted: 01/13/2017] [Indexed: 01/05/2023]
Abstract
Sublethal hypoxic or ischemic events can improve the tolerance of tissues, organs, and even organisms from subsequent lethal injury caused by hypoxia or ischemia. This phenomenon has been termed hypoxic or ischemic preconditioning (HPC or IPC) and is well established in the heart and the brain. This review aims to discuss HPC and IPC with respect to their historical development and advancements in our understanding of the neurochemical basis for their neuroprotective role. Through decades of collaborative research and studies of HPC and IPC in other organ systems, our understanding of HPC and IPC-induced neuroprotection has expanded to include: early- (phosphorylation targets, transporter regulation, interfering RNA) and late- (regulation of genes like EPO, VEGF, and iNOS) phase changes, regulators of programmed cell death, members of metabolic pathways, receptor modulators, and many other novel targets. The rapid acceleration in our understanding of HPC and IPC will help facilitate transition into the clinical setting.
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Affiliation(s)
- Sijie Li
- Beijing Key Laboratory of Hypoxic Conditioning Translational Medicine, Xuan Wu Hospital, Capital Medical University, Beijing, China; National Clinical Research Center for Geriatric Disorders, Beijing, China
| | - Adam Hafeez
- Department of Neurological Surgery, Wayne State University School of Medicine, Detroit, MI, USA
| | - Fatima Noorulla
- Department of Neurological Surgery, Wayne State University School of Medicine, Detroit, MI, USA
| | - Xiaokun Geng
- Department of Neurological Surgery, Wayne State University School of Medicine, Detroit, MI, USA; Department of Neurology, Luhe Hospital, Capital Medical University, Beijing, China
| | - Guo Shao
- Beijing Key Laboratory of Hypoxic Conditioning Translational Medicine, Xuan Wu Hospital, Capital Medical University, Beijing, China
| | - Changhong Ren
- Beijing Key Laboratory of Hypoxic Conditioning Translational Medicine, Xuan Wu Hospital, Capital Medical University, Beijing, China
| | - Guowei Lu
- Beijing Key Laboratory of Hypoxic Conditioning Translational Medicine, Xuan Wu Hospital, Capital Medical University, Beijing, China
| | - Heng Zhao
- Department of Neurosurgery, Stanford University, CA, USA
| | - Yuchuan Ding
- Beijing Key Laboratory of Hypoxic Conditioning Translational Medicine, Xuan Wu Hospital, Capital Medical University, Beijing, China; Department of Neurological Surgery, Wayne State University School of Medicine, Detroit, MI, USA
| | - Xunming Ji
- Beijing Key Laboratory of Hypoxic Conditioning Translational Medicine, Xuan Wu Hospital, Capital Medical University, Beijing, China; National Clinical Research Center for Geriatric Disorders, Beijing, China.
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9
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Multiple across-strain and within-strain QTLs suggest highly complex genetic architecture for hypoxia tolerance in channel catfish. Mol Genet Genomics 2016; 292:63-76. [PMID: 27734158 DOI: 10.1007/s00438-016-1256-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 10/03/2016] [Indexed: 10/20/2022]
Abstract
The ability to survive hypoxic conditions is important for various organisms, especially for aquatic animals. Teleost fish, representing more than 50 % of vertebrate species, are extremely efficient in utilizing low levels of dissolved oxygen in water. However, huge variations exist among various taxa of fish in their ability to tolerate hypoxia. In aquaculture, hypoxia tolerance is among the most important traits because hypoxia can cause major economic losses. Genetic enhancement for hypoxia tolerance in catfish is of great interest, but little was done with analysis of the genetic architecture of hypoxia tolerance. The objective of this study was to conduct a genome-wide association study to identify QTLs for hypoxia tolerance using the catfish 250K SNP array with channel catfish families from six strains. Multiple significant and suggestive QTLs were identified across and within strains. One significant QTL and four suggestive QTLs were identified across strains. Six significant QTLs and many suggestive QTLs were identified within strains. There were rare overlaps among the QTLs identified within the six strains, suggesting a complex genetic architecture of hypoxia tolerance. Overall, within-strain QTLs explained larger proportion of phenotypic variation than across-strain QTLs. Many of genes within these identified QTLs have known functions for regulation of oxygen metabolism and involvement in hypoxia responses. Pathway analysis indicated that most of these genes were involved in MAPK or PI3K/AKT/mTOR signaling pathways that were known to be important for hypoxia-mediated angiogenesis, cell proliferation, apoptosis and survival.
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Snyder S, Nadler LE, Bayley JS, Svendsen MBS, Johansen JL, Domenici P, Steffensen JF. Effect of closed v. intermittent-flow respirometry on hypoxia tolerance in the shiner perch Cymatogaster aggregata. JOURNAL OF FISH BIOLOGY 2016; 88:252-264. [PMID: 26768977 DOI: 10.1111/jfb.12837] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 09/28/2015] [Indexed: 06/05/2023]
Abstract
This study compares the critical oxygen saturation (O2 crit ) levels of the shiner perch Cymatogaster aggregata obtained using two different methods wherein hypoxia is induced either by the fish's respiration (closed respirometry) or by degassing oxygen with nitrogen (intermittent-flow respirometry). Fish exhibited loss of equilibrium at a higher O2 saturation in the closed respirometry method when compared with the intermittent-flow method. Utilization of closed respirometry yielded O2 crit measurements that were almost twice as high as those obtained with intermittent-flow respirometry. The lower hypoxia tolerance in closed respirometry is consistent with additional stress, caused by a build-up of ammonia and carbon dioxide and a faster rate in dissolved oxygen decline. The results indicate that these two methods of determining hypoxia tolerance in aquatic organisms are not comparable, and that much care should be given to method choice.
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Affiliation(s)
- S Snyder
- Scripps Institution of Oceanography, La Jolla, CA 92093-0208, U.S.A
| | - L E Nadler
- College of Marine and Environmental Sciences, ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Qld 4811, Australia
| | - J S Bayley
- University of Aarhus, Aarhus 8000, Denmark
| | - M B S Svendsen
- University of Copenhagen, Marine Biological Laboratory, Biological Institute, Strandpromenaden 5, DK-3000 Helsingør, Denmark
| | - J L Johansen
- University of Texas Marine Science Institute, Port Aransas, TX 78373, U.S.A
| | - P Domenici
- CNR-IAMC, Istituto per l'Ambiente Marino Costiero, Località Sa Mardini, 09072 Torregrande, Oristano, Italy
| | - J F Steffensen
- University of Copenhagen, Marine Biological Laboratory, Biological Institute, Strandpromenaden 5, DK-3000 Helsingør, Denmark
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Anttila K, Lewis M, Prokkola JM, Kanerva M, Seppänen E, Kolari I, Nikinmaa M. Warm acclimation and oxygen depletion induce species-specific responses in salmonids. ACTA ACUST UNITED AC 2015; 218:1471-7. [PMID: 25827840 DOI: 10.1242/jeb.119115] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 03/09/2015] [Indexed: 01/17/2023]
Abstract
Anthropogenic activities are greatly altering the habitats of animals, whereby fish are already encountering several stressors simultaneously. The purpose of the current study was to investigate the capacity of fish to respond to two different environmental stressors (high temperature and overnight hypoxia) separately and together. We found that acclimation to increased temperature (from 7.7±0.02°C to 14.9±0.05°C) and overnight hypoxia (daily changes from normoxia to 63-67% oxygen saturation), simulating climate change and eutrophication, had both antagonistic and synergistic effects on the capacity of fish to tolerate these stressors. The thermal tolerance of Arctic char (Salvelinus alpinus) and landlocked salmon (Salmo salar m. sebago) increased with warm acclimation by 1.3 and 2.2°C, respectively, but decreased when warm temperature was combined with overnight hypoxia (by 0.2 and 0.4°C, respectively). In contrast, the combination of the stressors more than doubled hypoxia tolerance in salmon and also increased hypoxia tolerance in char by 22%. Salmon had 1.2°C higher thermal tolerance than char, but char tolerated much lower oxygen levels than salmon at a given temperature. The changes in hypoxia tolerance were connected to the responses of the oxygen supply and delivery system. The relative ventricle mass was higher in cold- than in warm-acclimated salmon but the thickness of the compact layer of the ventricle increased with the combination of warm and hypoxia acclimation in both species. Char had also significantly larger hearts and thicker compact layers than salmon. The results illustrate that while fish can have protective responses when encountering a single environmental stressor, the combination of stressors can have unexpected species-specific effects that will influence their survival capacity.
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Affiliation(s)
- Katja Anttila
- Laboratory of Animal Physiology, Department of Biology, University of Turku, Turku 20014, Finland
| | - Mario Lewis
- Laboratory of Animal Physiology, Department of Biology, University of Turku, Turku 20014, Finland
| | - Jenni M Prokkola
- Laboratory of Animal Physiology, Department of Biology, University of Turku, Turku 20014, Finland
| | - Mirella Kanerva
- Laboratory of Animal Physiology, Department of Biology, University of Turku, Turku 20014, Finland
| | - Eila Seppänen
- Natural Resources Institute Finland (Luke), Laasalantie 9, Enonkoski 58175, Finland
| | - Irma Kolari
- Natural Resources Institute Finland (Luke), Laasalantie 9, Enonkoski 58175, Finland
| | - Mikko Nikinmaa
- Laboratory of Animal Physiology, Department of Biology, University of Turku, Turku 20014, Finland
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