Different patterns of chronic hypoxia lead to hierarchical adaptative mechanisms in goldfish metabolism

Some hypoxia-tolerant species, such as goldfish, experience intermittent and severe hypoxia in their natural habitat causing them to develop multiple physiological adaptations. However, in fish, the metabolic impact of regular hypoxic exposure on swimming performance in normoxia is less well understood. Therefore, we experimentally tested whether chronic exposure to constant (30 days at 10% air saturation) or intermittent hypoxia (3hrs in normoxia and 21hrs in hypoxia, 5 days a week) would result in similar metabolic and swimming performance benefits after reoxygenation. Moreover, half of the normoxic and intermittent hypoxic fish were put on a 20-day normoxic training regime. After these treatments, metabolic rate (standard and maximum metabolic rates: SMR and MMR) and swimming performance (critical swimming speed [Ucrit] and cost of transport [COT]) were assessed. In addition, enzyme activities (citrate synthase CS, cytochrome c oxidase COX and lactate dehydrogenase LDH) and mitochondrial respiration were examined in red muscle fibres. We found that acclimation to constant hypoxia resulted in (1) metabolic suppression (-45% SMR, and -27% MMR), (2) increased anaerobic capacity (+117% LDH), (3) improved swimming performance (+80% Ucrit, -71% COT) and (4) no changes at the mitochondrial level. Conversely, the enhancement of swimming performance was reduced following acclimation to intermittent hypoxia (+45% Ucrit, -41% COT), with a 55% decrease in aerobic scope, despite a significant increase in oxidative metabolism (+201% COX, +49% CS). This study demonstrates that constant hypoxia leads to the greatest benefit in swimming performance and that mitochondrial metabolic adjustments only provide minor help in coping with hypoxia.

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Vulnerability of individual fish to capture by trawling is influenced by capacity for anaerobic metabolism

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2015.0603 ◽

2015 ◽

Vol 282 (1813) ◽

pp. 20150603 ◽

Cited By ~ 27

Author(s):

Shaun S. Killen ◽

Julie J. H. Nati ◽

Cory D. Suski

Keyword(s):

Large Scale ◽

Swimming Performance ◽

Anaerobic Capacity ◽

Standard Metabolic Rate ◽

Metabolic Demand ◽

Evolutionary Forces ◽

Individual Fish ◽

Fundamental Information ◽

Behavioural Phenotypes ◽

And Function

The harvest of animals by humans may constitute one of the strongest evolutionary forces affecting wild populations. Vulnerability to harvest varies among individuals within species according to behavioural phenotypes, but we lack fundamental information regarding the physiological mechanisms underlying harvest-induced selection. It is unknown, for example, what physiological traits make some individual fish more susceptible to capture by commercial fisheries. Active fishing methods such as trawling pursue fish during harvest attempts, causing fish to use both aerobic steady-state swimming and anaerobic burst-type swimming to evade capture. Using simulated trawling procedures with schools of wild minnows Phoxinus phoxinus , we investigate two key questions to the study of fisheries-induced evolution that have been impossible to address using large-scale trawls: (i) are some individuals within a fish shoal consistently more susceptible to capture by trawling than others?; and (ii) if so, is this related to individual differences in swimming performance and metabolism? Results provide the first evidence of repeatable variation in susceptibility to trawling that is strongly related to anaerobic capacity and swimming ability. Maximum aerobic swim speed was also negatively correlated with vulnerability to trawling. Standard metabolic rate was highest among fish that were least vulnerable to trawling, but this relationship probably arose through correlations with anaerobic capacity. These results indicate that vulnerability to trawling is linked to anaerobic swimming performance and metabolic demand, drawing parallels with factors influencing susceptibility to natural predators. Selection on these traits by fisheries could induce shifts in the fundamental physiological makeup and function of descendent populations.

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Intermittent hypoxia increases ventilation and SaO2 during hypoxic exercise and hypoxic chemosensitivity

Journal of Applied Physiology ◽

10.1152/jappl.2001.90.4.1431 ◽

2001 ◽

Vol 90 (4) ◽

pp. 1431-1440 ◽

Cited By ~ 79

Author(s):

Keisho Katayama ◽

Yasutake Sato ◽

Yoshifumi Morotome ◽

Norihiro Shima ◽

Koji Ishida ◽

...

Keyword(s):

Intermittent Hypoxia ◽

Minute Ventilation ◽

Acute Hypoxia ◽

Arterial Oxygen Saturation ◽

Submaximal Exercise ◽

Arterial Oxygen ◽

Hypoxic Exposure ◽

Hypoxic Ventilatory Response ◽

Ventilatory Equivalent ◽

Hypoxic Exercise

The purpose of this study was 1) to test the hypothesis that ventilation and arterial oxygen saturation (SaO2 ) during acute hypoxia may increase during intermittent hypoxia and remain elevated for a week without hypoxic exposure and 2) to clarify whether the changes in ventilation and SaO2 during hypoxic exercise are correlated with the change in hypoxic chemosensitivity. Six subjects were exposed to a simulated altitude of 4,500 m altitude for 7 days (1 h/day). Oxygen uptake (V˙o 2), expired minute ventilation (V˙e), and SaO2 were measured during maximal and submaximal exercise at 432 Torr before (Pre), after intermittent hypoxia (Post), and again after a week at sea level (De). Hypoxic ventilatory response (HVR) was also determined. At both Post and De, significant increases from Pre were found in HVR at rest and in ventilatory equivalent for O2(V˙e/V˙o 2) and SaO2 during submaximal exercise. There were significant correlations among the changes in HVR at rest and inV˙e/V˙o 2 and SaO2 during hypoxic exercise during intermittent hypoxia. We conclude that 1 wk of daily exposure to 1 h of hypoxia significantly improved oxygenation in exercise during subsequent acute hypoxic exposures up to 1 wk after the conditioning, presumably caused by the enhanced hypoxic ventilatory chemosensitivity.

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Relations between morphology, buoyancy and energetics of requiem sharks

Royal Society Open Science ◽

10.1098/rsos.160406 ◽

2016 ◽

Vol 3 (10) ◽

pp. 160406 ◽

Cited By ~ 18

Author(s):

Gil Iosilevskii ◽

Yannis P. Papastamatiou

Keyword(s):

Body Temperature ◽

Negative Selection ◽

Swimming Performance ◽

Ontogenetic Changes ◽

Cost Of Transport ◽

Pectoral Fins ◽

Confined Spaces ◽

Reef Sharks ◽

The Cost ◽

Derivatives Of

Sharks have a distinctive shape that remained practically unchanged through hundreds of millions of years of evolution. Nonetheless, there are variations of this shape that vary between and within species. We attempt to explain these variations by examining the partial derivatives of the cost of transport of a generic shark with respect to buoyancy, span and chord of its pectoral fins, length, girth and body temperature. Our analysis predicts an intricate relation between these parameters, suggesting that ectothermic species residing in cooler temperatures must either have longer pectoral fins and/or be more buoyant in order to maintain swimming performance. It also suggests that, in general, the buoyancy must increase with size, and therefore, there must be ontogenetic changes within a species, with individuals getting more buoyant as they grow. Pelagic species seem to have near optimally sized fins (which minimize the cost of transport), but the majority of reef sharks could have reduced the cost of transport by increasing the size of their fins. The fact that they do not implies negative selection, probably owing to decreased manoeuvrability in confined spaces (e.g. foraging on a reef).

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Two patterns of daily hypoxic exposure and their effects on measures of chemosensitivity in humans

Journal of Applied Physiology ◽

10.1152/japplphysiol.00545.2007 ◽

2007 ◽

Vol 103 (6) ◽

pp. 1973-1978 ◽

Cited By ~ 23

Author(s):

Michael S. Koehle ◽

A. William Sheel ◽

William K. Milsom ◽

Donald C. McKenzie

Keyword(s):

Oxygen Saturation ◽

Intermittent Hypoxia ◽

Ventilatory Response ◽

Arterial Oxygen Saturation ◽

Arterial Oxygen ◽

Hypoxic Exposure ◽

Hypoxic Ventilatory Response ◽

The Third ◽

Long Duration ◽

The Mean

The purpose of this study was to compare chemoresponses following two different intermittent hypoxia (IH) protocols in humans. Ten men underwent two 7-day courses of poikilocapnic IH. The long-duration IH (LDIH) protocol consisted of daily 60-min exposures to normobaric 12% O2. The short-duration IH (SDIH) protocol comprised twelve 5-min bouts of 12% O2, separated by 5-min bouts of room air, daily. Isocapnic hypoxic ventilatory response (HVR) was measured daily during the protocol and 1 and 7 days following. Hypercapnic ventilatory response (HCVR) and CO2 threshold and sensitivity (by the modified Read rebreathing technique) were measured on days 1, 8, and 14. Following 7 days of IH, the mean HVR was significantly increased from 0.47 ± 0.07 and 0.47 ± 0.08 to 0.70 ± 0.06 and 0.79 ± 0.06 l·min−1·%SaO2−1 (LDIH and SDIH, respectively), where %SaO2 is percent arterial oxygen saturation. The increase in HVR reached a plateau after the third day. One week post-IH, HVR values were unchanged from baseline. HCVR increased from 3.0 ± 0.4 to 4.0 ± 0.5 l·min−1·mmHg−1. In both the hyperoxic and hypoxic modified Read rebreathing tests, the slope of the CO2/ventilation plot was unchanged by either intervention, but the CO2/ventilation curve shifted to the left following IH. There were no correlations between the changes in response to hypoxia and hypercapnia. There were no significant differences between the two IH protocols for any measures, indicating that comparable changes in chemoreflex control occur with either protocol. These results also suggest that the two methods of measuring CO2 response are not completely concordant and that the changes in CO2 control do not correlate with the increase in the HVR.

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Embryos of eastern rainbowfish Melanotaenia splendida splendida (Peters, 1866) tolerate fluctuating hypoxia

Marine and Freshwater Research ◽

10.1071/mf17192 ◽

2018 ◽

Vol 69 (6) ◽

pp. 987

Author(s):

N. Flint ◽

R. G. Pearson ◽

M. R. Crossland

Keyword(s):

Plant Material ◽

Sublethal Effects ◽

Larval Mortality ◽

Natural Habitat ◽

Hypoxia Tolerance ◽

Hypoxic Exposure ◽

Submerged Plant ◽

Embryo Viability ◽

Life History Stages ◽

Egg Incubation

Hypoxia can have profound sublethal effects on reproduction and embryonic development of some freshwater fish. In the present study, the effects of diel fluctuating hypoxia on embryo viability were investigated for the eastern rainbowfish Melanotaenia splendida splendida, a small-bodied species common in wetlands of tropical Queensland. After daily hypoxic exposure (minimum 5% saturation) from fertilisation until hatch, no effects were found on egg incubation time, egg and larval mortality, and viability and size of hatching larvae. Older life history stages of the species are vulnerable to this level of hypoxia. Embryos of phytolithophilic species are likely exposed to fluctuating dissolved oxygen saturations in their natural habitat, and hypoxia tolerance may be a requirement for fish species that spawn predominantly on submerged plant material.

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The rising cost of warming waters: effects of temperature on the cost of swimming in fishes

Biology Letters ◽

10.1098/rsbl.2011.0885 ◽

2011 ◽

Vol 8 (2) ◽

pp. 266-269 ◽

Cited By ~ 15

Author(s):

Andrew M. Hein ◽

Katrina J. Keirsted

Keyword(s):

Water Temperature ◽

Fish Species ◽

Global Climate ◽

Swimming Performance ◽

Metabolic Cost ◽

Quantitative Model ◽

The Body ◽

Energetic Cost ◽

Cost Of Transport ◽

The Cost

Understanding the effects of water temperature on the swimming performance of fishes is central in understanding how fish species will respond to global climate change. Metabolic cost of transport (COT)—a measure of the energy required to swim a given distance—is a key performance parameter linked to many aspects of fish life history. We develop a quantitative model to predict the effect of water temperature on COT. The model facilitates comparisons among species that differ in body size by incorporating the body mass-dependence of COT. Data from 22 fish species support the temperature and mass dependencies of COT predicted by our model, and demonstrate that modest differences in water temperature can result in substantial differences in the energetic cost of swimming.

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Naut Your Everyday Jellyfish Model: Exploring How Tentacles and Oral Arms Impact Locomotion

Fluids ◽

10.3390/fluids4030169 ◽

2019 ◽

Vol 4 (3) ◽

pp. 169 ◽

Cited By ~ 5

Author(s):

Jason G. Miles ◽

Nicholas A. Battista

Keyword(s):

Immersed Boundary Method ◽

Energy Efficient ◽

Swimming Performance ◽

Vortex Formation ◽

Fluid Mixing ◽

Immersed Boundary ◽

Number Density ◽

Cost Of Transport ◽

Fully Coupled ◽

Interaction Problem

Jellyfish are majestic, energy-efficient, and one of the oldest species that inhabit the oceans. It is perhaps the second item, their efficiency, that has captivated scientists for decades into investigating their locomotive behavior. Yet, no one has specifically explored the role that their tentacles and oral arms may have on their potential swimming performance. We perform comparative in silico experiments to study how tentacle/oral arm number, length, placement, and density affect forward swimming speeds, cost of transport, and fluid mixing. An open source implementation of the immersed boundary method was used (IB2d) to solve the fully coupled fluid–structure interaction problem of an idealized flexible jellyfish bell with poroelastic tentacles/oral arms in a viscous, incompressible fluid. Overall tentacles/oral arms inhibit forward swimming speeds, by appearing to suppress vortex formation. Nonlinear relationships between length and fluid scale (Reynolds Number) as well as tentacle/oral arm number, density, and placement are observed, illustrating that small changes in morphology could result in significant decreases in swimming speeds, in some cases by upwards of 80–90% between cases with or without tentacles/oral arms.

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Simulated maternal stress reduces offspring aerobic swimming performance in Pacific salmon

Conservation Physiology ◽

10.1093/conphys/coz095 ◽

2019 ◽

Vol 7 (1) ◽

Author(s):

Amanda I Banet ◽

Stephen J Healy ◽

Erika J Eliason ◽

Edward A Roualdes ◽

David A Patterson ◽

...

Keyword(s):

Oxygen Consumption ◽

Citrate Synthase ◽

Maternal Stress ◽

Pacific Salmon ◽

Swimming Performance ◽

Haemoglobin Concentration ◽

Aerobic Performance ◽

Aerobic Scope ◽

Lactate Dehydrogenase Activity ◽

Treatment Groups

Abstract Pacific salmon routinely encounter stressors during their upriver spawning migration, which have the potential to influence offspring through hormonally-mediated maternal effects. To disentangle genetic vs. hormonal effects on offspring swimming performance, we collected gametes from three species of Pacific salmon (Chinook, pink and sockeye) at the end of migration and exposed a subset of eggs from each female to cortisol baths to simulate high levels of maternal stress. Fertilised eggs were reared to fry and put through a series of aerobic swim trials. Results show that exposure to cortisol early in development reduces maximum oxygen consumption while swimming, and decreases aerobic scope in all three species. Resting oxygen consumption did not differ between cortisol and control treatment groups. We also examined several metrics that could influence aerobic performance, and found no differences between treatment groups in haematocrit%, haemoglobin concentration, heart mass, citrate synthase activity or lactate dehydrogenase activity. Though it was not the focus of this study, an interesting discovery was that pink salmon had a higher MO2max and aerobic scope relative to the other species, which was supported by a greater haematocrit, haemoglobin, a larger heart and higher CS activity. Some management and conservation practices for Pacific salmon focus efforts primarily on facilitating adult spawning. However, if deleterious effects of maternal stress acquired prior to spawning persist into the next generation, consideration will need to be given to sub-lethal effects that could be imparted onto offspring from maternal stress.

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Does a cannibal feeding strategy impart differential metabolic performance in young burbot (Lota lota maculosa)?

Conservation Physiology ◽

10.1093/conphys/coaa034 ◽

2020 ◽

Vol 8 (1) ◽

Author(s):

Amanda J Frazier ◽

Nathan R Jensen ◽

Shawn P Young ◽

Anne E Todgham

Keyword(s):

Citrate Synthase ◽

Feeding Strategy ◽

Natural Habitat ◽

Resting Metabolic Rate ◽

Habitat Alteration ◽

Traditional Practice ◽

Wild Stock ◽

Lota Lota ◽

Leading Role ◽

Metabolic Performance

Abstract The practice of mitigating cannibalism in aquaculture is an important focus for hatcheries seeking to maximize yield and has been maintained in hatcheries focusing on wild stock restoration. We hypothesize, however, that a cannibal feeding strategy may confer performance advantages over a non-cannibal feeding strategy and that perhaps cannibal size grading may not be optimal for hatcheries focusing on conservation goals. This study examined metabolic performance differences between cannibal and non-cannibal burbot, Lota lota maculosa, at the Kootenai Tribe of Idaho Twin Rivers Hatchery in Moyie Springs, ID, USA. After habitat alteration led to functional extinction of burbot in the region, the Twin Rivers Hatchery has played a leading role in the reestablishment of burbot in the Kootenai River, ID, and British Columbia. We examined morphometric data (weight, length and condition factor), whole animal resting metabolic rate and the enzyme activity of lactate dehydrogenase, citrate synthase and 3-hydroxyacyl-CoA dehydrogenase to describe the baseline metabolic performance of cannibal and non-cannibal burbot. Taken together, our results demonstrated significant differences in the metabolic strategies of cannibal vs. non-cannibal burbot, where cannibals relied more heavily on carbohydrate metabolism and non-cannibals relied more heavily on glycolytic and lipid metabolism. This study demonstrates the need to reevaluate the traditional practice of removing cannibal fish in conservation hatcheries, as it may not be the ideal strategy of raising the most robust individuals for release. When natural habitat conditions cannot be restored due to permanent habitat alteration, prioritizing release of higher performing individuals could help achieve conservation goals.

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Splenic contraction-induced reversible increase in hemoglobin concentration in intermittent hypoxia

Journal of Applied Physiology ◽

10.1152/jappl.1999.86.1.181 ◽

1999 ◽

Vol 86 (1) ◽

pp. 181-187 ◽

Cited By ~ 22

Author(s):

Ichiro Kuwahira ◽

Uguri Kamiya ◽

Tokuzen Iwamoto ◽

Yoshihiro Moue ◽

Tetsuya Urano ◽

...

Keyword(s):

Intermittent Hypoxia ◽

Hemoglobin Concentration ◽

Hypoxic Exposure ◽

Plasma Epinephrine ◽

Receptor Stimulation ◽

Blood Hemoglobin ◽

Underlying Mechanisms ◽

Blood Hemoglobin Concentration

The effect of intermittent hypoxia (IHx) on blood hemoglobin concentration ([Hb]) and the underlying mechanisms were studied in rats exposed to 10% O2, 1 h/day, for up to 5 wk. IHx protocols with longer daily hypoxic exposure show persistent polycythemia; however, it is unknown whether [Hb] increases transiently during hypoxia in protocols without polycythemia. Hypoxia produced a reversible [Hb] increase after 4 days of IHx but not in normoxic controls (NxC) or after shorter period of IHx. Splenectomy abolished the phenomenon. Plasma epinephrine and norepinephrine levels during hypoxia were comparable in IHx and NxC groups, but the epinephrine-induced [Hb] increase was larger in IHx. The α1- and α2-adrenoreceptor blockade (phentolamine) and α2-blockade (yohimbine) abolished the [Hb] increase of IHx rats. Conversely, α2-receptor stimulation (oxymetazoline) increased [Hb] during normoxia in IHx but not in NxC. In conclusion, this IHx protocol results in reversible [Hb] increases during hypoxia via splenic contraction mediated by increased α2-adrenoreceptor response. This may protect O2supply during hypoxia without the cardiovascular burden of polycythemia during normoxia.

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