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Onukwufor JO, Somo DA, Richards JG, Wood CM. Osmo-respiratory compromise in the mosshead sculpin (Clinocottus globiceps): effects of temperature, hypoxia, and re-oxygenation on rates of diffusive water flux and oxygen uptake. FISH PHYSIOLOGY AND BIOCHEMISTRY 2023; 49:853-866. [PMID: 37526893 DOI: 10.1007/s10695-023-01226-0] [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: 04/19/2023] [Accepted: 07/28/2023] [Indexed: 08/02/2023]
Abstract
In nature, mosshead sculpins (Clinocottus globiceps) are challenged by fluctuations in temperature and oxygen levels in their environment. However, it is unclear how mosshead sculpins modulate the permeability of their branchial epithelia to water and O2 in response to temperature or hypoxia stress. Acute decrease in temperature from 13 to 6 oC reduced diffusive water flux rate by 22% and ṀO2 by 51%, whereas acute increase in temperature from 13 to 25 oC increased diffusive water flux rate by 217% and ṀO2 by 140%, yielding overall Q10 values of 2.08 and 2.47 respectively. Acute reductions in oxygen tension from >95% to 20% or 10% air saturation did not impact diffusive water flux rates, however, ṀO2 was reduced significantly by 36% and 65% respectively. During 1-h or 3-h recovery periods diffusive water flux rates were depressed while ṀO2 exhibited overshoots beyond the normoxic control level. Many responses differed from those seen in our parallel earlier study on the tidepool sculpin, a cottid with similar hypoxia tolerance but much smaller gill area that occupies a similar environment. Overall, our data suggest that during temperature stress, diffusive water flux rates and ṀO2 follow the traditional osmo-respiratory compromise pattern, but during hypoxia and re-oxygenation stress, diffusive water flux rates are decoupled from ṀO2.
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Affiliation(s)
- John O Onukwufor
- Department of Zoology, The University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, 14642, USA.
| | - Derek A Somo
- Department of Zoology, The University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Jeffrey G Richards
- Department of Zoology, The University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Chris M Wood
- Department of Zoology, The University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
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2
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Somo DA, Chu K, Richards JG. Aerobic scope falls to nil at Pcrit and anaerobic ATP production increases below Pcrit in the tidepool sculpin, Oligocottus maculosus. Biol Lett 2022; 18:20220342. [PMID: 36475421 PMCID: PMC9727657 DOI: 10.1098/rsbl.2022.0342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The critical oxygen tension of whole-animal oxygen uptake rate, or Pcrit, has historically been defined as the oxygen partial pressure (PO2) at which aerobic scope falls to zero and further declines in PO2 require substrate-level phosphorylation to meet shortfalls in aerobic ATP production, thereby time-limiting survival. Despite the inclusion of aerobic scope and anaerobic ATP production in the definition, little effort has been made to verify that Pcrit measurements, the vast majority of which are obtained using respirometry in resting animals, actually reflect the predictions of zero aerobic scope and a transition to increasing reliance on anaerobic ATP production. To test these predictions, we compared aerobic scope and levels of whole-body lactate at oxygen partial pressures (PO2s) bracketing Pcrit obtained in resting fish during progressive hypoxia in the tidepool sculpin, Oligocottus maculosus. We found that aerobic scope falls to zero at Pcrit and, in resting fish exposed to PO2s < Pcrit, whole-body lactate accumulated pointing to an increased reliance on anaerobic ATP production. These results support the interpretation of Pcrit as a key oxygen threshold at which aerobic scope falls to nil and, below Pcrit, survival is time-limited based on anaerobic metabolic capacity.
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Affiliation(s)
- Derek A. Somo
- Department of Zoology, The University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| | - Ken Chu
- Department of Zoology, The University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| | - Jeffrey G. Richards
- Department of Zoology, The University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
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3
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van der Weele CM, Jeffery WR. Cavefish cope with environmental hypoxia by developing more erythrocytes and overexpression of hypoxia-inducible genes. eLife 2022; 11:69109. [PMID: 34984980 PMCID: PMC8765751 DOI: 10.7554/elife.69109] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 12/31/2021] [Indexed: 12/24/2022] Open
Abstract
Dark caves lacking primary productivity can expose subterranean animals to hypoxia. We used the surface-dwelling (surface fish) and cave-dwelling (cavefish) morphs of Astyanax mexicanus as a model for understanding the mechanisms of hypoxia tolerance in the cave environment. Primitive hematopoiesis, which is restricted to the posterior lateral mesoderm in other teleosts, also occurs in the anterior lateral mesoderm in Astyanax, potentially pre-adapting surface fish for hypoxic cave colonization. Cavefish have enlarged both hematopoietic domains and develop more erythrocytes than surface fish, which are required for normal development in both morphs. Laboratory-induced hypoxia suppresses growth in surface fish but not in cavefish. Both morphs respond to hypoxia by overexpressing hypoxia-inducible factor 1 (hif1) pathway genes, and some hif1 genes are constitutively upregulated in normoxic cavefish to similar levels as in hypoxic surface fish. We conclude that cavefish cope with hypoxia by increasing erythrocyte development and constitutive hif1 gene overexpression.
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Affiliation(s)
| | - William R Jeffery
- Department of Biology, University of Maryland, College Park, United States
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4
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Turko AJ, Rossi GS, Wright PA. More than Breathing Air: Evolutionary Drivers and Physiological Implications of an Amphibious Lifestyle in Fishes. Physiology (Bethesda) 2021; 36:307-314. [PMID: 34431416 DOI: 10.1152/physiol.00012.2021] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Amphibious and aquatic air-breathing fishes both exchange respiratory gasses with the atmosphere, but these fishes differ in physiology, ecology, and possibly evolutionary origins. We introduce a scoring system to characterize interspecific variation in amphibiousness and use this system to highlight important unanswered questions about the evolutionary physiology of amphibious fishes.
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Affiliation(s)
- Andy J Turko
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Giulia S Rossi
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada
| | - Patricia A Wright
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada
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5
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Houpt N, Borowiec BG, Bose APH, Brown NAW, Scott GR, Balshine S. Parental Males of the Plainfin Midshipman Are Physiologically Resilient to the Challenges of the Intertidal Zone. Physiol Biochem Zool 2020; 93:111-128. [PMID: 32013739 DOI: 10.1086/707408] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The decision of where to rear young is influenced by both the needs of offspring and the costs parents incur in certain rearing environments. Plainfin midshipman fish (Porichthys notatus) provide extended paternal care in rocky intertidal zones, where they experience regular bouts of aquatic hypoxia and air exposure during low-tide events. We investigated the physiological responses of plainfin midshipman males to three conditions for 6 h that simulate what these fish naturally experience during tidal cycles while nesting: normoxia, progressive hypoxia, or air exposure. Hypoxia- and air-exposed fish exhibited shifts in energy metabolites, driven largely by elevated lactate and glucose content and reduced glycogen content in several tissues (muscle, heart, liver, and brain), but the magnitude of these changes was relatively modest. Hematocrit increased most in air-exposed fish relative to normoxia-exposed fish, contributing to an increase in whole-blood hemoglobin concentration. Air exposure reduced swim bladder oxygen content, suggesting that internal O2 stores are drawn on during air exposure. In a second experiment, we found that aquatic surface respiration and gill ventilation frequency increased in hypoxia-exposed fish relative to normoxia-exposed fish. Overall, our results suggest that plainfin midshipman overcome the challenges of the intertidal environment through a variety of physiological strategies and exhibit little physiological disturbance in response to the fluctuating and extreme conditions created by regular low tides.
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6
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Somo DA, Onukwufor JO, Wood CM, Richards JG. Interactive effects of temperature and hypoxia on diffusive water flux and oxygen uptake rate in the tidepool sculpin, Oligocottus maculosus. Comp Biochem Physiol A Mol Integr Physiol 2020; 250:110781. [PMID: 32763468 DOI: 10.1016/j.cbpa.2020.110781] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 07/31/2020] [Accepted: 07/31/2020] [Indexed: 01/07/2023]
Abstract
The osmorespiratory compromise hypothesis posits that respiratory epithelial characteristics and physiological regulatory mechanisms which promote gas permeability also increase permeability to ions and water. The hypothesis therefore predicts that physiological responses which increase effective gas permeability will result in increased effective ion and water permeabilities. Though analyses of water and gas effective permeabilities using high temperature have generally supported the hypothesis, water permeability responses to hypoxia remain equivocal and the combination of high temperature and hypoxia untested. We measured diffusive water flux (DWF) and oxygen uptake rate (Ṁo2) in response to acute temperature change, hypoxia, and the combination of high temperature and hypoxia in a hypoxia-tolerant intertidal fish, the tidepool sculpin (Oligocottus maculosus). In support of the osmorespiratory compromise hypothesis, Ṁo2 and DWF increased with temperature. In contrast, DWF decreased with hypoxia at a constant temperature, a result consistent with previously observed decoupling of water and gas effective permeabilities during hypoxia exposure in some hypoxia tolerant fishes. However, DWF levels during simultaneous high temperature and hypoxia exposure were not different from fish exposed to high temperature in normoxia, possibly suggesting a failure of the mechanism responsible for down-regulating DWF in hypoxia. These results, together with time-course analysis of hypoxia exposure and normoxic recovery, suggest that tidepool sculpins actively downregulate effective water permeability in hypoxia but the mechanism fails with multi-stressor exposure. Future investigations of the mechanistic basis of the regulation of gill permeability will be key to understanding the role of this regulatory ability in the persistence of this species in the dynamic intertidal environment.
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Affiliation(s)
- Derek A Somo
- Department of Zoology, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
| | - John O Onukwufor
- Department of Zoology, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Chris M Wood
- Department of Zoology, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Jeffrey G Richards
- Department of Zoology, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada
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7
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Borowiec BG, Hoffman RD, Hess CD, Galvez F, Scott GR. Interspecific variation in hypoxia tolerance and hypoxia acclimation responses in killifish from the family Fundulidae. J Exp Biol 2020; 223:jeb209692. [PMID: 31988166 PMCID: PMC7044458 DOI: 10.1242/jeb.209692] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 01/20/2020] [Indexed: 01/25/2023]
Abstract
Hypoxia is a pervasive stressor in aquatic environments, and both phenotypic plasticity and evolutionary adaptation could shape the ability to cope with hypoxia. We investigated evolved variation in hypoxia tolerance and the hypoxia acclimation response across fundulid killifishes that naturally experience different patterns of hypoxia exposure. We compared resting O2 consumption rate (ṀO2 ), and various indices of hypoxia tolerance [critical O2 tension (Pcrit), regulation index (RI), O2 tension (PO2 ) at loss of equilibrium (PLOE) and time to LOE (tLOE) at 0.6 kPa O2] in Fundulus confluentus, Fundulus diaphanus, Fundulus heteroclitus, Fundulus rathbuni, Lucania goodei and Lucania parva We examined the effects of chronic (28 days) exposure to constant hypoxia (2 kPa) or nocturnal intermittent hypoxia (12 h normoxia:12 h hypoxia) in a subset of species. Some species exhibited a two-breakpoint model in ṀO2 caused by early, modest declines in ṀO2 in moderate hypoxia. We found that hypoxia tolerance varied appreciably across species: F. confluentus was the most tolerant (lowest PLOE and Pcrit, longest tLOE), whereas F. rathbuni and F. diaphanus were the least tolerant. However, there was not a consistent pattern of interspecific variation for different indices of hypoxia tolerance, with or without taking phylogenetic relatedness into account, probably because these different indices are underlain by partially distinct mechanisms. Hypoxia acclimation generally improved hypoxia tolerance, but the magnitude of plasticity and responsiveness to different hypoxia patterns varied interspecifically. Our results therefore suggest that hypoxia tolerance is a complex trait that is best appreciated by considering multiple indices of tolerance.
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Affiliation(s)
| | - Ryan D Hoffman
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Chelsea D Hess
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Fernando Galvez
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Graham R Scott
- Department of Biology, McMaster University, Hamilton, ON, Canada, L8S 4K1
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8
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Moulton TL, Chapman LJ, Krahe R. Effects of hypoxia on aerobic metabolism and active electrosensory acquisition in the African weakly electric fish Marcusenius victoriae. JOURNAL OF FISH BIOLOGY 2020; 96:496-505. [PMID: 31845335 DOI: 10.1111/jfb.14234] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 12/13/2019] [Indexed: 06/10/2023]
Abstract
Environmental hypoxia has effected numerous and well-documented anatomical, physiological and behavioural adaptations in fishes. Comparatively little is known about hypoxia's impacts on sensing because it is difficult to quantify sensory acquisition in vivo. Weakly electric fishes, however, rely heavily on an easily-measurable sensory modality-active electric sensing-whereby individuals emit and detect electric organ discharges (EODs). In this study, hypoxia tolerance of a mormyrid weakly electric fish, Marcusenius victoriae, was assessed by examining both its metabolic and EOD rates using a critical threshold (pcrit ) paradigm. The routine metabolic rate was 1.42 mg O2 h-1 , and the associated critical oxygen tension was 14.34 mmHg. Routine EOD rate was 5.68 Hz with an associated critical tension of 15.14 mmHg. These metabolic indicators of hypoxia tolerance measured in this study were consistent with those in previous studies on M. victoriae and other weakly electric fishes. Furthermore, our results suggest that some aerobic processes may be reduced in favour of maintaining the EOD rate under extreme hypoxia. These findings underscore the importance of the active electrosensory modality to these hypoxia-tolerant fish.
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Affiliation(s)
- Tyler L Moulton
- Department of Biology, McGill University, Montreal, Quebec, Canada
- Department of Biology, Hamilton College, Clinton, New York, USA
| | - Lauren J Chapman
- Department of Biology, McGill University, Montreal, Quebec, Canada
| | - Rüdiger Krahe
- Department of Biology, McGill University, Montreal, Quebec, Canada
- Institut für Biologie, Humboldt-Universität zu Berlin, Berlin, Germany
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9
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Lau GY, Arndt S, Murphy MP, Richards JG. Species- and tissue-specific differences in ROS metabolism during exposure to hypoxia and hyperoxia plus recovery in marine sculpins. ACTA ACUST UNITED AC 2019; 222:jeb.206896. [PMID: 31628206 DOI: 10.1242/jeb.206896] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 10/12/2019] [Indexed: 12/16/2022]
Abstract
Animals that inhabit environments that fluctuate in oxygen must not only contend with disruptions to aerobic metabolism, but also the potential effects of reactive oxygen species (ROS). The goal of this study was to compare aspects of ROS metabolism in response to O2 variability (6 h hypoxia or hyperoxia, with subsequent normoxic recovery) in two species of intertidal sculpin fishes (Cottidae, Actinopterygii) that can experience O2 fluctuations in their natural environment and differ in whole-animal hypoxia tolerance. To assess ROS metabolism, we measured the ratio of glutathione to glutathione disulfide as an indicator of tissue redox environment, MitoP/MitoB ratio to assess in vivo mitochondrial ROS generation, thiobarbituric acid reactive substances (TBARS) for lipid peroxidation, and total oxidative scavenging capacity (TOSC) in the liver, brain and gill. In the brain, the more hypoxia-tolerant O ligocottus maculosus showed large increases in TBARS levels following hypoxia and hyperoxia exposure that were generally not associated with large changes in mitochondrial H2O2 In contrast, the less-tolerant S corpaenichthys marmoratus showed no significant changes in TBARS or mitochondrial H2O2 in the brain. More moderate increases were observed in the liver and gill of O. maculosus exposed to hypoxia and hyperoxia with normoxic recovery, whereas S. marmoratus had a greater response to O2 variability in these tissues compared with the brain. Our results show a species- and tissue-specific relationship between hypoxia tolerance and ROS metabolism.
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Affiliation(s)
- Gigi Y Lau
- Department of Zoology, University of British Columbia, 6270 University Blvd, Vancouver, BC V6T 1Z4, Canada
| | - Sabine Arndt
- MRC Mitochondrial Biology Unit, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK
| | - Michael P Murphy
- MRC Mitochondrial Biology Unit, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK
| | - Jeffrey G Richards
- Department of Zoology, University of British Columbia, 6270 University Blvd, Vancouver, BC V6T 1Z4, Canada
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10
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Clarke SB, Chapman LJ, Krahe R. The effect of normoxia exposure on hypoxia tolerance and sensory sampling in a swamp-dwelling mormyrid fish. Comp Biochem Physiol A Mol Integr Physiol 2019; 240:110586. [PMID: 31648062 DOI: 10.1016/j.cbpa.2019.110586] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 09/22/2019] [Accepted: 09/23/2019] [Indexed: 11/27/2022]
Abstract
Effects of energetic limitations on the performance of sensory systems are generally difficult to quantify. Weakly electric fishes provide an ideal model system to quantify the effects of metabolic stressors on sensory information acquisition, because they use an active-sensing strategy that permits easy measurement of the sensing effort. These fishes discharge an electric signal and sense perturbations of the resulting electric field. We used the mormyrid Petrocephalus degeni to quantify the relationship between routine metabolic rate and the rate of sensory sampling (rate of electric organ discharge, EOD) while under progressive hypoxia by quantifying the critical oxygen tension (PC-MR) and the critical electric organ discharge threshold (PC-EOD). PC-MR was significantly higher in fish acclimated to normoxia for over 40 days compared to animals tested within 1-5 days of capture from a hypoxic swamp, which suggests high costs of maintaining hypoxia tolerance; however, there was no acclimation effect on PC-EOD. All P. degeni reached their PC-EOD prior to their PC-MR. However, below the respective critical tension value, EOD rate decreased more gradually than the metabolic rate suggesting that the fish were increasing the proportion of their energy budget allocated to acquiring sensory information as dissolved-oxygen levels dropped. Trade-offs between sensory sampling and other physiological functions are also suggested by the increase in routine EOD rate with long-term normoxia acclimation, in contrast to metabolic rate, which showed no significant changes. These results highlight the relationship between sensory sampling and metabolic rate in response to progressive hypoxia and the plasticity of hypoxia tolerance.
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Affiliation(s)
- Shelby B Clarke
- Department of Biology, McGill University, 1205 Ave du Docteur-Penfield, Montreal, QC H3A1B1, Canada.
| | - Lauren J Chapman
- Department of Biology, McGill University, 1205 Ave du Docteur-Penfield, Montreal, QC H3A1B1, Canada.
| | - Rüdiger Krahe
- Department of Biology, McGill University, 1205 Ave du Docteur-Penfield, Montreal, QC H3A1B1, Canada; Humboldt-Universität zu Berlin, Institute of Biology, Unter den Linden 6, 10099 Berlin, Germany.
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11
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Bressman NR, Love JW, King TW, Horne CG, Ashley-Ross MA. Emersion and Terrestrial Locomotion of the Northern Snakehead ( Channa argus) on Multiple Substrates. Integr Org Biol 2019; 1:obz026. [PMID: 33791540 PMCID: PMC7671134 DOI: 10.1093/iob/obz026] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Most fishes known for terrestrial locomotion are small and/or elongate. Northern snakeheads (Channa argus) are large, air-breathing piscivores anecdotally known for terrestrial behaviors. Our goals were to determine their environmental motivations for emersion, describe their terrestrial kinematics for fish 3.0-70.0 cm and compare kinematics among four substrates. For emersion experiments, C. argus was individually placed into aquatic containers with ramps extending through the surface of the water, and exposed to 15 ecologically-relevant environmental conditions. For kinematic experiments, fish were filmed moving on moist bench liner, grass, artificial turf, and a flat or tilted rubber boat deck. Videos were digitized for analysis in MATLAB and electromyography was used to measure muscular activity. Only the low pH (4.8), high salinity (30 ppt), and high dCO2 (10% seltzer solution) treatments elicited emersion responses. While extreme, these conditions do occur in some of their native Asian swamps. Northern snakeheads >4.5 cm used a unique form of axial-appendage-based terrestrial locomotion involving cyclic oscillations of the axial body, paired with near-simultaneous movements of both pectoral fins. Individuals ≤3.5 cm used tail-flip jumps to travel on land. Northern snakeheads also moved more quickly on complex, three-dimensional substrates (e.g., grass) than on smooth substrates (e.g., bench liner), and when moving downslope. Release of snakeheads onto land by humans or accidentally by predators may be more common than voluntary emersion, but because northern snakeheads can respire air, it may be necessary to factor in the ability to spread overland into the management of this invasive species.
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Affiliation(s)
- N R Bressman
- Department of Biology, Wake Forest University, Winston-Salem, NC 27109, USA
| | - J W Love
- Maryland Department of Natural Resources, Annapolis, MD 21401, USA
| | - T W King
- Department of Biology, Wake Forest University, Winston-Salem, NC 27109, USA
| | - C G Horne
- Department of Biology, Wake Forest University, Winston-Salem, NC 27109, USA
| | - M A Ashley-Ross
- Department of Biology, Wake Forest University, Winston-Salem, NC 27109, USA
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12
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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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13
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Mandic M, Regan MD. Can variation among hypoxic environments explain why different fish species use different hypoxic survival strategies? ACTA ACUST UNITED AC 2018; 221:221/21/jeb161349. [PMID: 30381477 DOI: 10.1242/jeb.161349] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In aquatic environments, hypoxia is a multi-dimensional stressor that can vary in O2 level (partial pressure of O2 in water, PwO2 ), rate of induction and duration. Natural hypoxic environments can therefore be very different from one another. For the many fish species that have evolved to cope with these different hypoxic environments, survival requires adjusting energy supply and demand pathways to maintain energy balance. The literature describes innumerable ways that fishes combine aerobic metabolism, anaerobic metabolism and metabolic rate depression (MRD) to accomplish this, but it is unknown whether the evolutionary paths leading to these different strategies are determined primarily by species' phylogenetic histories, genetic constraint or their native hypoxic environments. We explored this idea by devising a four-quadrant matrix that bins different aquatic hypoxic environments according to their duration and PwO2 characteristics. We then systematically mined the literature for well-studied species native to environments within each quadrant, and, for each of 10 case studies, described the species' total hypoxic response (THR), defined as its hypoxia-induced combination of sustained aerobic metabolism, enhanced anaerobic metabolism and MRD, encompassing also the mechanisms underlying these metabolic modes. Our analysis revealed that fishes use a wide range of THRs, but that distantly related species from environments within the same matrix quadrant have converged on similar THRs. For example, environments of moderately hypoxic PwO2 favoured predominantly aerobic THRs, whereas environments of severely hypoxic PwO2 favoured MRD. Capacity for aerial emergence as well as predation pressure (aquatic and aerial) also contributed to these responses, in addition to other biotic and abiotic factors. Generally, it appears that the particular type of hypoxia experienced by a fish plays a major role in shaping its particular THR.
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Affiliation(s)
- Milica Mandic
- Department of Biology, University of Ottawa, Ottawa, ON, Canada, K1N 6N5
| | - Matthew D Regan
- Comparative Biosciences Department, University of Wisconsin-Madison, Madison, WI 35706, USA
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Rees BB, Matute LA. Repeatable Interindividual Variation in Hypoxia Tolerance in the Gulf Killifish, Fundulus grandis. Physiol Biochem Zool 2018; 91:1046-1056. [DOI: 10.1086/699596] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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15
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Turko AJ, Tatarenkov A, Currie S, Earley RL, Platek A, Taylor DS, Wright PA. Emersion behaviour underlies variation in gill morphology and aquatic respiratory function in the amphibious fish Kryptolebias marmoratus. ACTA ACUST UNITED AC 2018; 221:jeb.168039. [PMID: 29511069 DOI: 10.1242/jeb.168039] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 03/01/2018] [Indexed: 12/21/2022]
Abstract
Fishes acclimated to hypoxic environments often increase gill surface area to improve O2 uptake. In some species, surface area is increased via reduction of an interlamellar cell mass (ILCM) that fills water channels between gill lamellae. Amphibious fishes, however, may not increase gill surface area in hypoxic water because these species can, instead, leave water and breathe air. To differentiate between these possibilities, we compared wild amphibious mangrove rivulus Kryptolebias marmoratus from two habitats that varied in O2 availability - a hypoxic freshwater pool versus nearly anoxic crab burrows. Fish captured from crab burrows had less gill surface area (as ILCMs were enlarged by ∼32%), increased rates of normoxic O2 consumption and increased critical O2 tension compared with fish from the freshwater pool. Thus, wild mangrove rivulus do not respond to near-anoxic water by decreasing metabolism or increasing O2 extraction. Instead, fish from the crab burrow habitat spent three times longer out of water, which probably caused the observed changes in gill morphology and respiratory phenotype. We also tested whether critical O2 tension is influenced by genetic heterozygosity, as K. marmoratus is one of only two hermaphroditic vertebrate species that can produce both self-fertilized (inbred) or out-crossed (more heterozygous) offspring. We found no evidence for inbreeding depression, suggesting that self-fertilization does not impair respiratory function. Overall, our results demonstrate that amphibious fishes that inhabit hypoxic aquatic habitats can use a fundamentally different strategy from that used by fully aquatic water-breathing fishes, relying on escape behaviour rather than metabolic depression or increased O2 extraction ability.
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Affiliation(s)
- A J Turko
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - A Tatarenkov
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA 92697, USA
| | - S Currie
- Department of Biology, Mount Allison University, Sackville, New Brunswick, Canada E4L 1E2
| | - R L Earley
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487, USA
| | - A Platek
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - D S Taylor
- Brevard County Environmentally Endangered Lands Program, Melbourne, FL 32904, USA
| | - P A Wright
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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16
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Black MN, Henry EF, Adams OA, Bennett JCF, MacCormack TJ. Environmentally relevant concentrations of amine-functionalized copper nanoparticles exhibit different mechanisms of bioactivity in Fundulus Heteroclitus in fresh and brackish water. Nanotoxicology 2017; 11:1070-1085. [DOI: 10.1080/17435390.2017.1395097] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Merryl N. Black
- Department of Chemistry and Biochemistry, Mount Allison University, Sackville, New Brunswick, Canada
| | - Elenor F. Henry
- Department of Chemistry and Biochemistry, Mount Allison University, Sackville, New Brunswick, Canada
| | - Olivia A. Adams
- Department of Chemistry and Biochemistry, Mount Allison University, Sackville, New Brunswick, Canada
| | | | - Tyson James MacCormack
- Department of Chemistry and Biochemistry, Mount Allison University, Sackville, New Brunswick, Canada
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17
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McDonnell LH, Chapman LJ. At the edge of the thermal window: effects of elevated temperature on the resting metabolism, hypoxia tolerance and upper critical thermal limit of a widespread African cichlid. CONSERVATION PHYSIOLOGY 2015; 3:cov050. [PMID: 27293734 PMCID: PMC4778473 DOI: 10.1093/conphys/cov050] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 09/28/2015] [Accepted: 10/07/2015] [Indexed: 05/29/2023]
Abstract
Tropical inland fishes are predicted to be especially vulnerable to thermal stress because they experience small temperature fluctuations that may select for narrow thermal windows. In this study, we measured resting metabolic rate (RMR), critical oxygen tension (P crit) and critical thermal maximum (CTMax) of the widespread African cichlid (Pseudocrenilabrus multicolor victoriae) in response to short-term acclimation to temperatures within and above their natural thermal range. Pseudocrenilabrus multicolor collected in Lake Kayanja, Uganda, a population living near the upper thermal range of the species, were acclimated to 23, 26, 29 and 32°C for 3 days directly after capture, and RMR and P crit were then quantified. In a second group of P. multicolor from the same population, CTMax and the thermal onset of agitation were determined for fish acclimated to 26, 29 and 32°C for 7 days. Both RMR and P crit were significantly higher in fish acclimated to 32°C, indicating decreased tolerance to hypoxia and increased metabolic requirements at temperatures only slightly (∼1°C) above their natural thermal range. The CTMax increased with acclimation temperature, indicating some degree of thermal compensation induced by short-term exposure to higher temperatures. However, agitation temperature (likely to represent an avoidance response to increased temperature during CTMax trials) showed no increase with acclimation temperature. Overall, the results of this study demonstrate that P. multicolor is able to maintain its RMR and P crit across the range of temperatures characteristic of its natural habitat, but incurs a higher cost of resting metabolism and reduced hypoxia tolerance at temperatures slightly above its present range.
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Affiliation(s)
| | - Lauren J. Chapman
- Biology Department, McGill University, Montreal, Quebec, Canada H3A 1B1
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18
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LeMoine CMR, Bucking C, Craig PM, Walsh PJ. Divergent Hypoxia Tolerance in Adult Males and Females of the Plainfin Midshipman (Porichthys notatus). Physiol Biochem Zool 2014; 87:325-33. [DOI: 10.1086/674565] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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19
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Dhillon RS, Yao L, Matey V, Chen BJ, Zhang AJ, Cao ZD, Fu SJ, Brauner CJ, Wang YS, Richards JG. Interspecific differences in hypoxia-induced gill remodeling in carp. Physiol Biochem Zool 2013; 86:727-39. [PMID: 24241069 DOI: 10.1086/673180] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
The gills of many fish, but in particular those of crucian carp (Carassius carassius) and goldfish (Carassius auratus), are capable of extensive remodeling in response to changes in oxygen (O2), temperature, and exercise. In this study, we investigated the interspecific variation in hypoxia-induced gill modeling and hypoxia tolerance in 10 closely related groups of cyprinids (nine species, with two strains of Cyprinus carpio). There was significant variation in hypoxia tolerance, measured as the O2 tension (P(O2)) at which fish lost equilibrium (LOEcrit), among the 10 groups of carp. In normoxia, there was a significant, phylogenetically independent relationship between mass-specific gill surface area and LOEcrit, with the more hypoxia-tolerant carp having smaller gills than their less hypoxia-tolerant relatives. All groups of carp, except the Chinese bream (Megalobrama pellegrini), increased mass-specific gill surface area in response to 48 h of exposure to hypoxia (0.7 kPa) through reductions in the interlamellar cell mass (ILCM) volume. The magnitude of the hypoxia-induced reduction in the ILCM was negatively correlated with LOEcrit (and thus positively correlated with hypoxia tolerance), independent of phylogeny. The hypoxia-induced changes in gill morphology resulted in reduced variation in mass-specific gill surface area among species and eliminated the relationship between LOEcrit and mass-specific gill surface area. While behavioral responses to hypoxia differed among the carp groups, there were no significant relationships between hypoxia tolerance and the Po2 at which aquatic surface respiration (ASR) was initiated or the total number of ASR events observed during progressive hypoxia. Our results are the first to show that the extent of gill remodeling in cyprinids is associated with hypoxia tolerance in a phylogenetically independent fashion.
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Affiliation(s)
- Rashpal S Dhillon
- Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia V6T 1Z4, Canada; 2Department of Biology, San Diego State University, San Diego, California; 3Laboratory of Evolutionary Physiology and Behavior, Chongqing Key Laboratory of Animal Biology, Chongqing Normal University, Chongqing, China; 4Department of Biology, Queen's University, 116 Barrie Street, Kingston, Ontario K7L 3N6, Canada
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20
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Yang H, Cao ZD, Fu SJ. The effects of diel-cycling hypoxia acclimation on the hypoxia tolerance, swimming capacity and growth performance of southern catfish (Silurus meridionalis). Comp Biochem Physiol A Mol Integr Physiol 2013; 165:131-8. [PMID: 23474254 DOI: 10.1016/j.cbpa.2013.02.028] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 02/24/2013] [Accepted: 02/25/2013] [Indexed: 12/01/2022]
Abstract
To investigate the effects of diel-cycling hypoxia acclimation on the hypoxia tolerance, swimming and growth performance of juvenile southern catfish, we initially measured the critical oxygen tension (P(crit)), oxygen thresholds of aquatic surface respiration (ASR) and loss of equilibrium (LOE) of diel-cycling hypoxia-acclimated (15 d, 7:00-21:00, dissolved oxygen level (DO) = 7.0 ± 0.2 mg L(-1); 21:00-7:00, DO = 3.0 ± 0.2 mg L(-1)) and non-acclimated (15 d, DO = 7.0 ± 0.2 mg L(-1)) southern catfish at 25 °C. We then measured the critical swimming speed (U(crit)) and metabolic rate (MR) of hypoxia-acclimated and non-acclimated fish (under both hypoxic and normoxic conditions). The feeding rate (FR), feeding efficiency (FE) and specific growth rate (SGR) of fish in hypoxia-acclimated and non-acclimated groups were also measured. The P(crit), ASR and LOE of hypoxia-acclimated fish were significantly lower than those of non-acclimated fish. Hypoxia acclimation resulted in a significantly higher U(crit) when the individuals swam in hypoxia. The U(crit), maximum metabolic rate (MMR) and metabolic scope (MS) of both the hypoxia-acclimated and non-acclimated fish all decreased with the decrease of DO. However, the U(crit), MMR and MS decreased by 31, 43 and 54%, respectively, in non-acclimated fish, whereas these values decreased by 15, 28 and 29%, respectively, in hypoxia-acclimated fish, which suggests that hypoxia-acclimated fish were less sensitive to the DO decrease. The FR, FE and SGR all decreased by 21, 20 and 45%, respectively, in the hypoxia-acclimated group compared to the non-acclimated group. This result suggests that diel-cycling hypoxia acclimation improved the hypoxia tolerance and aerobic swimming performance of southern catfish, whereas impaired the growth performance. The high hypoxia tolerance and physiological plasticity to hypoxia-acclimated southern catfish may be related to its lower maintenance energy expenditure, sit-and-wait lifestyle and bottom-dwelling living environment condition (usually facing oxygen fluctuation). The growth performance of so-called 'visceral type' fish species, such as southern catfish, are more sensitive to hypoxia compared to other fish species because of their high peak post-prandial metabolic rate, which may be restrained by the limited aerobic metabolic scope in hypoxia.
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Affiliation(s)
- Han Yang
- Laboratory of Evolutionary Physiology and Behavior, Chongqing Key Laboratory of Animal Biology, Chongqing Normal University, Chongqing, 400047, China
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21
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Knope ML, Scales JA. Adaptive morphological shifts to novel habitats in marine sculpin fishes. J Evol Biol 2013; 26:472-82. [PMID: 23316868 DOI: 10.1111/jeb.12088] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Revised: 10/16/2012] [Accepted: 11/16/2012] [Indexed: 01/28/2023]
Abstract
Sculpin fishes of the North American Pacific Coast provide an ideal opportunity to examine whether adaptive morphological character shifts have facilitated occupation of novel habitat types because of their well-described phylogeny and ecology. In this group, the basal-rooted species primarily occupy the subtidal habitat, whereas the species in the most distal clades are found in the intertidal. We tested multiple evolutionary models to determine whether changes in body size and changes in number of scales are adaptive for habitat use in sculpins. Based on a statistically robust, highly resolved molecular phylogeny of 26 species of sculpins, in combination with morphometric and habitat affinity data, our analyses show that an adaptive model based on habitat use best explains changes in body size and number of scales. The habitat model was statistically supported over models of neutral evolution, stabilizing selection across all habitats, and three clade-based models. We suggest that loss of scales and reduction of body size in the intertidal may facilitate cutaneous breathing in air when tidepools become hypoxic during low tides. This study demonstrates how the combined use of phylogenetic, ecological and statistical approaches helps to identify traits that are likely adaptive to novel habitats.
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Affiliation(s)
- M L Knope
- Department of Biology, Stanford University, Stanford, CA 94305, USA.
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22
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Urbina MA, Glover CN. Should I stay or should I go?: Physiological, metabolic and biochemical consequences of voluntary emersion upon aquatic hypoxia in the scaleless fish Galaxias maculatus. J Comp Physiol B 2012; 182:1057-67. [PMID: 22645056 DOI: 10.1007/s00360-012-0678-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2012] [Revised: 05/08/2012] [Accepted: 05/10/2012] [Indexed: 11/26/2022]
Abstract
Hypoxia represents a significant challenge to most fish, forcing the development of behavioural, physiological and biochemical adaptations to survive. It has been previously shown that inanga (Galaxias maculatus) display a complex behavioural repertoire to escape aquatic hypoxia, finishing with the fish voluntarily emerging from the water and aerially respiring. In the present study we evaluated the physiological, metabolic and biochemical consequences of both aquatic hypoxia and emersion in inanga. Inanga successfully tolerated up to 6 h of aquatic hypoxia or emersion. Initially, this involved enhancing blood oxygen-carrying capacity, followed by the induction of anaerobic metabolism. Only minor changes were noted between emersed fish and those maintained in aquatic hypoxia, with the latter group displaying a higher mean cell haemoglobin content and a reduced haematocrit after 6 h. Calculations suggest that inanga exposed to both aquatic hypoxia and air reduced oxygen uptake and also increased anaerobic contribution to meet energy demands, but the extent of these changes was small compared with hypoxia-tolerant fish species. Overall, these findings add to previous studies suggesting that inanga are relatively poorly adapted to survive aquatic hypoxia.
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Affiliation(s)
- Mauricio A Urbina
- School of Biological Sciences, University of Canterbury, Christchurch, New Zealand.
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23
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Whitehead A. Comparative genomics in ecological physiology: toward a more nuanced understanding of acclimation and adaptation. J Exp Biol 2012; 215:884-91. [DOI: 10.1242/jeb.058735] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Summary
Organisms that live in variable environments must adjust their physiology to compensate for environmental change. Modern functional genomics technologies offer global top-down discovery-based tools for identifying and exploring the mechanistic basis by which organisms respond physiologically to a detected change in the environment. Given that populations and species from different niches may exhibit different acclimation abilities, comparative genomic approaches may offer more nuanced understanding of acclimation responses, and provide insight into the mechanistic and genomic basis of variable acclimation. The physiological genomics literature is large and growing, as is the comparative evolutionary genomics literature. Yet, expansion of physiological genomics experiments to exploit taxonomic variation remains relatively undeveloped. Here, recent advances in the emerging field of comparative physiological genomics are considered, including examples of plants, bees and fish, and opportunities for further development are outlined particularly in the context of climate change research. Elements of robust experimental design are discussed with emphasis on the phylogenetic comparative approach. Understanding how acclimation ability is partitioned among populations and species in nature, and knowledge of the relevant genes and mechanisms, will be important for characterizing and predicting the ecological and evolutionary consequences of human-accelerated environmental change.
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Affiliation(s)
- Andrew Whitehead
- Department of Environmental Toxicology, University of California, Davis, CA 95616, USA
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24
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Urbina MA, Forster ME, Glover CN. Leap of faith: voluntary emersion behaviour and physiological adaptations to aerial exposure in a non-aestivating freshwater fish in response to aquatic hypoxia. Physiol Behav 2011; 103:240-7. [PMID: 21316378 DOI: 10.1016/j.physbeh.2011.02.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 01/26/2011] [Accepted: 02/04/2011] [Indexed: 10/18/2022]
Abstract
Lowland stream fauna in areas of intensive agriculture are increasingly under threat from anthropogenic activities leading to eutrophication and subsequent hypoxia. Survival of hypoxic episodes depends upon a combination of behavioural and physiological adaptations. Responses of inanga (Galaxias maculatus: Galaxiidae) to aquatic hypoxia were investigated in the laboratory. Contrary to expectation inanga did not display behaviour that might reduce energy expenditure during oxygen limitation, with swimming activity slightly, but significantly elevated relative to normoxia. Instead, as dissolved oxygen concentrations decreased, the fish moved higher in the water column, increased their swimming speed and exhibited aquatic surface respiration. Physiological changes such as enhanced opercular frequency were also noted. As hypoxia deepened inanga started to leap out of the water, emersing themselves on a floating platform. Once emersed, fish exhibited an enhanced oxygen consumption rate compared to hypoxic fish. Thus inanga appear better adapted to escape hypoxia (a behavioural adaptation) rather than tolerate it (physiological adaptation). The emersion strategy used for inanga in response to severe hypoxia is in agreement with their ability to take up more oxygen from the air than from hypoxic water and therefore may justify the potentially increased risks of desiccation and predation associated with leaving the water.
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Affiliation(s)
- Mauricio A Urbina
- School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand.
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25
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Richards JG. Physiological, behavioral and biochemical adaptations of intertidal fishes to hypoxia. J Exp Biol 2011; 214:191-9. [DOI: 10.1242/jeb.047951] [Citation(s) in RCA: 207] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Summary
Hypoxia survival in fish requires a well-coordinated response to either secure more O2 from the hypoxic environment or to limit the metabolic consequences of an O2 restriction at the mitochondria. Although there is a considerable amount of information available on the physiological, behavioral, biochemical and molecular responses of fish to hypoxia, very little research has attempted to determine the adaptive value of these responses. This article will review current attempts to use the phylogenetically corrected comparative method to define physiological and behavioral adaptations to hypoxia in intertidal fish and further identify putatively adaptive biochemical traits that should be investigated in the future. In a group of marine fishes known as sculpins, from the family Cottidae, variation in hypoxia tolerance, measured as a critical O2 tension (Pcrit), is primarily explained by variation in mass-specific gill surface area, red blood cell hemoglobin–O2 binding affinity, and to a lesser extent variation in routine O2 consumption rate (). The most hypoxia-tolerant sculpins consistently show aquatic surface respiration (ASR) and aerial emergence behavior during hypoxia exposure, but no phylogenetically independent relationship has been found between the thresholds for initiating these behaviors and Pcrit. At O2 levels below Pcrit, hypoxia survival requires a rapid reorganization of cellular metabolism to suppress ATP consumption to match the limited capacity for O2-independent ATP production. Thus, it is reasonable to speculate that the degree of metabolic rate suppression and the quantity of stored fermentable fuel is strongly selected for in hypoxia-tolerant fishes; however, these assertions have not been tested in a phylogenetic comparative model.
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Affiliation(s)
- Jeffrey G. Richards
- Department of Zoology, The University of British Columbia, 6270 University Blvd, Vancouver, BC, V6T 1Z4, Canada
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