| 1. |
- Andreassen, Anna H., et al.
(författare)
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Brain dysfunction during warming is linked to oxygen limitation in larval zebrafish
- 2022
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Ingår i: Proceedings of the National Academy of Science of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 119:39
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the physiological mechanisms that limit animal thermal tolerance is crucial in predicting how animals will respond to increasingly severe heat waves. Despite their importance for understanding climate change impacts, these mechanisms underlying the upper thermal tolerance limits of animals are largely unknown. It has been hypothesized that the upper thermal tolerance in fish is limited by the thermal tolerance of the brain and is ultimately caused by a global brain depolarization. In this study, we developed methods for measuring the upper thermal limit (CTmax) in larval zebrafish (Danio rerio) with simultaneous recordings of brain activity using GCaMP6s calcium imaging in both free-swimming and agar-embedded fish. We discovered that during warming, CTmax precedes, and is therefore not caused by, a global brain depolarization. Instead, the CTmax coincides with a decline in spontaneous neural activity and a loss of neural response to visual stimuli. By manipulating water oxygen levels both up and down, we found that oxygen availability during heating affects locomotor-related neural activity, the neural response to visual stimuli, and CTmax. Our results suggest that the mechanism limiting the upper thermal tolerance in zebrafish larvae is insufficient oxygen availability causing impaired brain function.
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| 2. |
- Asheim, Eirik R., et al.
(författare)
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Acute warming tolerance (CT max ) in zebrafish ( Danio rerio ) appears unaffected by changes in water salinity
- 2024
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Ingår i: PEERJ. - 2167-8359. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Tolerance against acute warming is an essential trait that can determine how organisms cope during heat waves, yet the mechanisms underlying it remain elusive. Water salinity has previously been suggested to modulate warming tolerance in fish and may therefore provide clues towards these limiting mechanisms. Here, using the critical thermal maximum (CTmax) test, we investigated whether short (2 hours) and long (10 days) term exposure to different water salinities (2 hours: 0-5 ppt, 10 days: 0-3 ppt) affected acute warming tolerance in zebrafish (N = 263). We found that water salinity did not affect the warming tolerance of zebrafish at either time point, indicating that salinity does not affect the mechanism limiting acute warming tolerance in zebrafish at these salinity ranges, and that natural fluctuations in salinity levels might not have a large impact on acute warming tolerance in wild zebrafish.
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| 3. |
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| 4. |
- Bresolin de Souza, Karine, et al.
(författare)
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Effects of increased CO2on fish gill and plasma proteome
- 2014
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:7
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Tidskriftsartikel (refereegranskat)abstract
- Ocean acidification and warming are both primarily caused by increased levels of atmospheric CO2, and marine organisms are exposed to these two stressors simultaneously. Although the effects of temperature on fish have been investigated over the last century, the long-term effects of moderate CO2 exposure and the combination of both stressors are almost entirely unknown. A proteomics approach was used to assess the adverse physiological and biochemical changes that may occur from the exposure to these two environmental stressors. We analysed gills and blood plasma of Atlantic halibut (Hippoglossus hippoglossus) exposed to temperatures of 12°C (control) and 18°C (impaired growth) in combination with control (400 μatm) or high-CO2 water (1000 μatm) for 14 weeks. The proteomic analysis was performed using two-dimensional gel electrophoresis (2DE) followed by Nanoflow LC-MS/MS using a LTQ-Orbitrap. The high-CO2 treatment induced the up-regulation of immune system-related proteins, as indicated by the up-regulation of the plasma proteins complement component C3 and fibrinogen β chain precursor in both temperature treatments. Changes in gill proteome in the high-CO2 (18°C) group were mostly related to increased energy metabolism proteins (ATP synthase, malate dehydrogenase, malate dehydrogenase thermostable, and fructose-1,6-bisphosphate aldolase), possibly coupled to a higher energy demand. Gills from fish exposed to high-CO 2 at both temperature treatments showed changes in proteins associated with increased cellular turnover and apoptosis signalling (annexin 5, eukaryotic translation elongation factor 1γ, receptor for protein kinase C, and putative ribosomal protein S27). This study indicates that moderate CO2-driven acidification, alone and combined with high temperature, can elicit biochemical changes that may affect fish health. © 2014 Bresolin de Souza et al.
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| 5. |
- Brijs, Jeroen, et al.
(författare)
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Experimental manipulations of tissue oxygen supply do not affect warming tolerance of European perch
- 2015
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 218, s. 2448-2454
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Tidskriftsartikel (refereegranskat)abstract
- A progressive inability of the cardiorespiratory system to maintain systemic oxygen supply at elevated temperatures has been suggested to reduce aerobic scope and the upper thermal limit of aquatic ectotherms. However, few studies have directly investigated the dependence of thermal limits on oxygen transport capacity. By manipulating oxygen availability (via environmental hyperoxia) and blood oxygen carrying capacity (via experimentally-induced anemia) in European perch (Perca fluviatilis, Linneaus), we investigated the effects of oxygen transport capacity on aerobic scope and the critical thermal maximum (CTmax). Hyperoxia resulted in a two-fold increase in aerobic scope at the control temperature of 23°C, but this did not translate to an elevated CTmax in comparison with control fish (34.6±0.1°C vs. 34.0±0.5°C, respectively). Anemia (∼43% reduction in haemoglobin concentration) did not cause a reduction in aerobic scope nor CTmax (33.8±0.3°C) compared with control fish. Additionally, oxygen consumption rates of anemic perch during thermal ramping increased in a similar exponential manner as in control fish, highlighting that perch have an impressive capacity to compensate for a substantial reduction in blood oxygen carrying capacity. Taken together, these results indicate that oxygen limitation is not a universal mechanism determining the CTmax of fishes.
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| 6. |
- Brijs, Jeroen, et al.
(författare)
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Extreme blood-boosting capacity of an Antarctic fish represents an adaptation to life in a sub-zero environment
- 2020
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 223:2
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Tidskriftsartikel (refereegranskat)abstract
- Blood doping, the practice of boosting the oxygen carrying capacity of blood, is an illegal strategy used by human athletes to enhance aerobic capacity and athletic performance. Interestingly, the practice of boosting blood oxygen carrying capacity is also naturally prevalent in the animal kingdom via the splenic release of stored erythrocytes. Here, we demonstrate that an Antarctic notothenioid fish, the bald notothen (Pagothenia borchgrevinki), is a master of this practice. Because of the sub-zero environment these fish inhabit, they sequester a large proportion of erythrocytes in the spleen during times of inactivity to reduce the energetic and physiological costs associated with continuously pumping highly viscous blood around the body. However, in response to metabolically demanding situations (i.e. exercise and feeding), these fish contract the spleen to eject stored erythrocytes into circulation, which boosts blood oxygen carrying capacity by up to 207% (cf. exercise-induced increases of ∼40-60% in a range of other vertebrates and ∼5-25% in blood-doping athletes). By evaluating cardiorespiratory differences between splenectomized (unable to release erythrocytes from the spleen) and sham-operated individuals, we demonstrate the metabolic benefits (i.e. aerobic scope increase of 103%) and the cardiovascular trade-offs (i.e. ventral aortic blood pressure and cardiac workload increase of 12% and 30%, respectively) associated with the splenic blood-boosting strategy. In conclusion, this strategy provides bald notothens with an extraordinary facultative aerobic scope that enables an active lifestyle in the extreme Antarctic marine environment, while minimizing the energetic and physiological costs of transporting highly viscous blood during times of reduced energetic demand.
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| 7. |
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| 8. |
- Carney Almroth, Bethanie, 1974, et al.
(författare)
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Warmer water temperature results in oxidative damage in an Antarctic fish, the bald notothen
- 2015
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Ingår i: Journal of Experimental Marine Biology and Ecology. - : Elsevier BV. - 0022-0981 .- 1879-1697. ; 468, s. 130-137
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Tidskriftsartikel (refereegranskat)abstract
- Global climate change is predicted to result in increases in water temperature in the polar regions, but the full consequences of this for marine fish species are not understood, especially with regard to cellular mechanisms underlying oxidative stress. Warmer temperatures could potentially result in increased oxidative stress, and it is not known whether stenothermal fish can cope with this on a cellular and physiological level. In order to address this, we exposed bald notothen (Pagothenta borchgrevinki), a fish species endemic to Antarctica, to an increase in temperature from -1.6 degrees C to 4 degrees C and measured the effects on oxidative stress including antioxidant defenses, oxidative damage in proteins and lipids, and transcriptional regulation of involved genes. We show that the fish responds to an acute (12 h) temperature increase with increased antioxidant defenses. However, these antioxidant defenses were similar to basal levels following long-term (3 weeks) exposure to the higher temperature and moreover, these individuals also had higher levels of oxidative damage. These results indicate that this species has the ability to alter levels of endogenous antioxidants, but that this response is transient and insufficient to protect against oxidative damage. These effects may have serious consequences for these fish in a warmer future since long-term consequences of this accumulation of damaged lipids and proteins are associated with aging and known to include decreased cellular function, disease and eventually cell death. (C) 2015 Elsevier B.V. All rights reserved.
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| 9. |
- Clark, T. D., et al.
(författare)
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Aerobic scope measurements of fishes in an era of climate change: respirometry, relevance and recommendations
- 2013
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 216:15, s. 2771-2782
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Forskningsöversikt (refereegranskat)abstract
- Measurements of aerobic scope [the difference between minimum and maximum oxygen consumption rate ((M) over dot(O2,min) and (M) over dot(O2,max), respectively)] are increasing in prevalence as a tool to address questions relating to fish ecology and the effects of climate change. However, there are underlying issues regarding the array of methods used to measure aerobic scope across studies and species. In an attempt to enhance quality control before the diversity of issues becomes too great to remedy, this paper outlines common techniques and pitfalls associated with measurements of (M) over dot(O2,min), (M) over dot(O2,max) and aerobic scope across species and under different experimental conditions. Additionally, we provide a brief critique of the oxygen-and capacity-limited thermal tolerance (OCLTT) hypothesis, a concept that is intricately dependent on aerobic scope measurements and is spreading wildly throughout the literature despite little evidence for its general applicability. It is the intention of this paper to encourage transparency and accuracy in future studies that measure the aerobic metabolism of fishes, and to highlight the fundamental issues with assuming broad relevance of the OCLTT hypothesis.
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| 10. |
- Clark, Timothy D., et al.
(författare)
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Ocean acidification does not impair the behaviour of coral reef fishes
- 2020
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Ingår i: Nature. - : Springer Nature. - 0028-0836 .- 1476-4687. ; 577:7790, s. 370-375
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Tidskriftsartikel (refereegranskat)abstract
- The partial pressure of CO2 in the oceans has increased rapidly over the past century, driving ocean acidification and raising concern for the stability of marine ecosystems1,2,3. Coral reef fishes are predicted to be especially susceptible to end-of-century ocean acidification on the basis of several high-profile papers4,5 that have reported profound behavioural and sensory impairments—for example, complete attraction to the chemical cues of predators under conditions of ocean acidification. Here, we comprehensively and transparently show that—in contrast to previous studies—end-of-century ocean acidification levels have negligible effects on important behaviours of coral reef fishes, such as the avoidance of chemical cues from predators, fish activity levels and behavioural lateralization (left–right turning preference). Using data simulations, we additionally show that the large effect sizes and small within-group variances that have been reported in several previous studies are highly improbable. Together, our findings indicate that the reported effects of ocean acidification on the behaviour of coral reef fishes are not reproducible, suggesting that behavioural perturbations will not be a major consequence for coral reef fishes in high CO2 oceans.
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| 11. |
- Clark, Timothy D., et al.
(författare)
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Response to Farrell and to Portner and Giomi.
- 2013
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 216:23, s. 4495-4497
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Tidskriftsartikel (refereegranskat)
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| 12. |
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| 13. |
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| 14. |
- Cowan, Zara-Louise, et al.
(författare)
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A novel method for measuring acute thermal tolerance in fish embryos.
- 2023
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Ingår i: Conservation physiology. - 2051-1434. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Aquatic ectotherms are vulnerable to thermal stress, with embryos predicted to be more sensitive than juveniles and adults. When examining the vulnerability of species and life stages to warming, comparable methodology must be used to obtain robust conclusions. Critical thermal methodology is commonly used to characterize acute thermal tolerances in fishes, with critical thermal maximum (CTmax) referring to the acute upper thermal tolerance limit. At this temperature, fish exhibit loss of controlled locomotion due to a temperature-induced collapse of vital physiological functions. While it is relatively easy to monitor behavioural responses and measure CTmax in larval and adult fish, this is more challenging in embryos, leading to a lack of data on this life stage, or that studies rely on potentially incomparable metrics. Here, we present a novel method for measuring CTmax in fish embryos, defined by the temperature at which embryos stop moving. Additionally, we compare this measurement with the temperature of the embryos' last heartbeat, which has previously been proposed as a method for measuring embryonic CTmax. We found that, like other life stages, late-stage embryos exhibited a period of increased activity, peaking approximately 2-3°C before CTmax. Measurements of CTmax based on last movement are more conservative and easier to record in later developmental stages than measurements based on last heartbeat, and they also work well with large and small embryos. Importantly, CTmax measurements based on last movement in embryos are similar to measurements from larvae and adults based on loss of locomotory control. Using last heartbeat as CTmax in embryos likely overestimates acute thermal tolerance, as the heart is still beating when loss of response/equilibrium is reached in larvae/adults. The last movement technique described here allows for comparisons of acute thermal tolerance of embryos between species and across life stages, and as a response variable to treatments.
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| 15. |
- Desforges, Jessica E., et al.
(författare)
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The ecological relevance of critical thermal maxima methodology for fishes
- 2023
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Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112 .- 1095-8649.
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Tidskriftsartikel (refereegranskat)abstract
- Critical thermal maxima methodology (CTM) has been used to infer acute upper thermal tolerance in fishes since the 1950s, yet its ecological relevance remains debated. In this study, the authors synthesize evidence to identify methodological concerns and common misconceptions that have limited the interpretation of critical thermal maximum (CTmax; value for an individual fish during one trial) in ecological and evolutionary studies of fishes. They identified limitations of, and opportunities for, using CTmax as a metric in experiments, focusing on rates of thermal ramping, acclimation regimes, thermal safety margins, methodological endpoints, links to performance traits and repeatability. Care must be taken when interpreting CTM in ecological contexts, because the protocol was originally designed for ecotoxicological research with standardized methods to facilitate comparisons within study individuals, across species and contexts. CTM can, however, be used in ecological contexts to predict impacts of environmental warming, but only if parameters influencing thermal limits, such as acclimation temperature or rate of thermal ramping, are taken into account. Applications can include mitigating the effects of climate change, informing infrastructure planning or modelling species distribution, adaptation and/or performance in response to climate-related temperature change. The authors’ synthesis points to several key directions for future research that will further aid the application and interpretation of CTM data in ecological contexts.
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| 16. |
- Ekström, Andreas, 1979, et al.
(författare)
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Cardiac oxygen limitation during an acute thermal challenge in the European perch: Effects of chronic environmental warming and experimental hyperoxia
- 2016
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Ingår i: American Journal of Physiology. Regulatory Integrative and Comparative Physiology. - : American Physiological Society. - 0363-6119 .- 1522-1490. ; 311:2
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Tidskriftsartikel (refereegranskat)abstract
- Oxygen supply to the heart has been hypothesized to limit cardiac performance and whole animal acute thermal tolerance (CTmax) in fish. We tested these hypotheses by continuously measuring venous oxygen tension (PvO2) and cardiovascular variables in vivo during acute warming in European perch (Perca fluviatilis) from a reference area during summer (18°C) and a chronically heated area (Biotest enclosure) that receives warm effluent water from a nuclear power plant and is normally 5–10°C above ambient (24°C at the time of experiments). While CTmax was 2.2°C higher in Biotest compared with reference perch, the peaks in cardiac output and heart rate prior to CTmax occurred at statistically similar PvO2 values (2.3– 4.0 kPa), suggesting that cardiac failure occurred at a common critical PvO2 threshold. Environmental hyperoxia (200% air saturation) increased PvO2 across temperatures in reference fish, but heart rate still declined at a similar temperature. CTmax of reference fish increased slightly (by 0.9°C) in hyperoxia, but remained significantly lower than in Biotest fish despite an improved cardiac output due to an elevated stroke volume. Thus, while cardiac oxygen supply appears critical to elevate stroke volume at high temperatures, oxygen limitation may not explain the bradycardia and arrhythmia that occur prior to CTmax. Acute thermal tolerance and its thermal plasticity can, therefore, only be partially attributed to cardiac failure from myocardial oxygen limitations, and likely involves limiting factors on multiple organizational levels. © 2016 the American Physiological Society.
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| 17. |
- Ekström, Andreas, 1979, et al.
(författare)
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Chronic environmental warming alters cardiovascular and haematological stress responses in European perch (Perca fluviatilis)
- 2016
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Ingår i: Journal of Comparative Physiology B-Biochemical Systemic and Environmental Physiology. - : Springer Science and Business Media LLC. - 0174-1578 .- 1432-136X. ; 186:8, s. 1023-1031
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Tidskriftsartikel (refereegranskat)abstract
- Environmental warming and acute stress increase cardiorespiratory activity in ectothermic animals like fish. While thermal acclimation can buffer the direct thermal effects on basal cardiorespiratory function during chronic warming, little is known about how acclimation affects stress-induced cardiorespiratory responses. We compared cardiovascular and haematological responses to chasing stress in cannulated wild European perch (Perca fluviatilis) from a reference area at natural temperature (16 A degrees C) with perch from the 'Biotest enclosure'; an experimental system chronically warmed (22 A degrees C) by effluents from a nuclear power plant. Routine blood pressure was similar, but Biotest perch had slightly higher resting heart rate (59.9 +/- 2.8 vs 51.3 +/- 2.9 beats min(-1)), although the Q (10) for heart rate was 1.3, indicating pronounced thermal compensation. Chasing stress caused hypertension and a delayed tachycardia in both groups, but the maximum heart rate increase was 2.5-fold greater in Biotest fish (43.3 +/- 4.3 vs 16.9 +/- 2.7 beats min(-1)). Moreover, the pulse pressure response after stress was greater in reference fish, possibly due to the less pronounced tachycardia or a greater ventricular pressure generating capacity and thermally mediated differences in aortic compliance. Baseline haematological status was also similar, but after chasing stress, the haematocrit was higher in Biotest fish due to exacerbated red blood cell swelling. This study highlights that while eurythermal fishes can greatly compensate routine cardiorespiratory functions through acclimation processes, stress-induced responses may still differ markedly. This knowledge is essential when utilising cardiorespiratory variables to quantify and compare stress responses across environmental temperatures, and to forecast energetic costs and physiological constraints in ectothermic animals under global warming.
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| 18. |
- Ekström, Andreas, 1979, et al.
(författare)
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Effects of autonomic blockade on acute thermal tolerance and cardioventilatory performance in rainbow trout, Oncorhynchus mykiss
- 2014
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Ingår i: Journal of Thermal Biology. - : Elsevier BV. - 0306-4565. ; 44, s. 47-54
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Tidskriftsartikel (refereegranskat)abstract
- Predicted future increases in global temperature may impose challenges for ectothermic animals like fish, but the physiological mechanisms determining the critical thermal maximum (CTmax) are not well understood. One hypothesis suggests that impaired cardiac performance, limited by oxygen supply, is an important underlying mechanism. Since vagal bradycardia is suggested to improve cardiac oxygenation and adrenergic stimulation may improve cardiac contractility and protect cardiac function at high temperatures, we predicted that pharmacological blockade of cardiac autonomic control would lower CTmax. Rainbow trout was instrumented with a flow probe and a ventilation catheter for cardioventilatory recordings and exposed to an acute thermal challenge until CTmax following selective pharmacological blockade of muscarinic or beta-adrenergic receptors. Contrary to our prediction, CTmax (~26 degrees C) was unchanged between treatments. While beta-adrenergic blockade reduced heart rate it did not impair cardiac stroke volume across temperatures suggesting that compensatory increases in cardiac filling pressure may serve to maintain cardiac output. While warming resulted in significant tachycardia and increased cardiac output, a high cholinergic tone on the heart was observed at temperatures approaching CTmax. This may represent a mechanism to maintain scope for heart rate and possibly to improve myocardial contractility and oxygen supply at high temperatures. This is the first study evaluating the importance of autonomic cardiac control on thermal tolerance in fish. While no effects on CTmax were observed, this study raises important questions about the underlying mechanisms determining thermal tolerance limits in ectothermic animals.
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| 19. |
- Ern, R., et al.
(författare)
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Physiological Mechanisms of Acute Upper Thermal Tolerance in Fish
- 2023
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Ingår i: Physiology. - : American Physiological Society. - 1548-9213 .- 1548-9221. ; 38:3, s. 141-158
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Tidskriftsartikel (refereegranskat)abstract
- This review is focused on the questions of why fish exhibit heat failure at thermal extremes and which physiological mechanisms determine the acute upper thermal tolerance. We propose that rapid direct thermal impacts on fish act through three fundamental molecular mechanisms reaction rates, protein structure, and membrane fluidity. During acute warming, these molecular effects then lead to loss of equilibrium and death through various cellular, organ, and physiological pathways. These pathways include mitochondrial dysfunction, oxygen limitation, and impacted excitability of excitable cells and eventually lead to neural and/or muscular failure. The pathways may also lead to loss of homeostasis and subsequent heat failure. There is strong evidence in some species for oxygen limitation in these processes and strong evidence against it in other species and contexts. The limiting mechanisms during acute warming therefore appear to differ between species, life stages, and recent thermal history. We conclude that a single mechanism underpinning the acute upper thermal tolerance across species and contexts will not be found. Therefore, we propose future avenues of research that can elucidate major patterns of physiological thermal limitations in fish
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| 20. |
- Ern, Rasmus, et al.
(författare)
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The OptoReg system: a simple and inexpensive solution for regulating water oxygen
- 2024
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Ingår i: CONSERVATION PHYSIOLOGY. - 2051-1434. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- This paper introduces a new system for regulating water oxygen levels, using the FireSting-O2 meter. This OptoReg system is inexpensive, easy to build and user-friendly. This paper provides detailed instructions on building and using the system, and it presents a dataset that illustrates the system's accuracy and stability. This paper describes an optocoupler-based regulation apparatus for saturation manipulation of oxygen in water (OptoReg). This system enables control of solenoid valves for oxygen and nitrogen gases using a FireSting-O2 meter, an optocoupler box and an electronic switch box. The hardware components connect to a computer through Universal Serial Bus (USB) cables. The control software is free and has a graphical user interface, making it easy to use. With the OptoReg system, any lab with a computer running Microsoft Windows operating system and a 4-channel FireSting-O2 meter can easily and cheaply set up four independently controlled systems for regulating water oxygen levels. Here, we describe how to assemble and run the OptoReg system and present a data set demonstrating the high precision and stability of the OptoReg system during static acclimation experiments and dynamic warming trials.
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| 21. |
- Fahlman, Johan, 1988-
(författare)
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The fate and effect of pharmaceuticals in boreal surface waters
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Traces of pharmaceuticals are often found in streams, rivers, and lakes as the result of effluent water discharge. This dissertation aims to create a better understanding of the fate of drugs in aquatic ecosystems and how oxazepam, an anxiolytic pharmaceutical commonly detected in surface waters, affects the behavior of perch (Perca fluviatilis). To address these issues, I used a series of large-scale field experiments to evaluate predictions made in controlled laboratory experiments. My dissertation shows that small-scale incubations commonly used to assess the persistence of pharmaceuticals (trimethoprim, diclofenac, hydroxyzine, diphenhydramine and oxazepam) in aquatic environments effectively predicts the fate of dissolved drugs in freshwater during the first week of contamination. However, these experiments and the conceptual models failed to predict that pharmaceuticals can remain dissolved in freshwater for months. In addition, the results suggest that the drugs remain bioactive for months and that the uptake of different drugs varied widely between trophic levels. For example, benthic species generally had a higher affinity to accumulate the studied drugs than species in higher trophic levels; however, the anxiolytic drug oxazepam was found in perch. To test the effect of oxazepam on perch behavior, I used acoustic telemetry to track the perch in situ (i.e., in the ponds). The in situ behavior of perch correlated with laboratory behavior when findings from several trials were merged into multidimensional behavioral profiles of the studied individuals, although oxazepam did not conclusively affect perch behavior in line with earlier theories, when though concentrations were much higher than concentrations measured in any contaminated environments. I conclude that simplified laboratory experiments have some predictive power regarding the fate and effects of pharmaceuticals in complex natural ecosystems, but laboratory environments may underestimate persistence of drugs in aquatic ecosystems and fail to detect important social drivers of animal behavior in natural settings.
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| 22. |
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| 23. |
- Forsgren, Elisabet, et al.
(författare)
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Elevated CO2 affects embryonic development and larval phototaxis in a temperate marine fish
- 2013
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 3:11, s. 3637-3646
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Tidskriftsartikel (refereegranskat)abstract
- As an effect of anthropogenic CO2 emissions, the chemistry of the world's oceans is changing. Understanding how this will affect marine organisms and ecosystems are critical in predicting the impacts of this ongoing ocean acidification. Work on coral reef fishes has revealed dramatic effects of elevated oceanic CO2 on sensory responses and behavior. Such effects may be widespread but have almost exclusively been tested on tropical reef fishes. Here we test the effects elevated CO2 has on the reproduction and early life history stages of a temperate coastal goby with paternal care by allowing goby pairs to reproduce naturally in an aquarium with either elevated (ca 1400atm) CO2 or control seawater (ca 370atm CO2). Elevated CO2 did not affect the occurrence of spawning nor clutch size, but increased embryonic abnormalities and egg loss. Moreover, we found that elevated CO2 significantly affected the phototactic response of newly hatched larvae. Phototaxis is a vision-related fundamental behavior of many marine fishes, but has never before been tested in the context of ocean acidification. Our findings suggest that ocean acidification affects embryonic development and sensory responses in temperate fishes, with potentially important implications for fish recruitment.
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| 24. |
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| 25. |
- Green, Leon, et al.
(författare)
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Elevated carbon dioxide alters the plasma composition and behaviour of a shark
- 2014
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Ingår i: Biology Letters. - : The Royal Society. - 1744-9561 .- 1744-957X. ; 10:9
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Tidskriftsartikel (refereegranskat)abstract
- Increased carbon emissions from fossil fuels are increasing the pCO(2) of the ocean surface waters in a process called ocean acidification. Elevated water pCO(2) can induce physiological and behavioural effects in teleost fishes, although there appear to be large differences in sensitivity between species. There is currently no information available on the possible responses to future ocean acidification in elasmobranch fishes. We exposed small-spotted catsharks (Scyliorhinus canicula) to either control conditions or a year 2100 scenario of 990 matm pCO(2) for four weeks. We did not detect treatment effects on growth, resting metabolic rate, aerobic scope, skin denticle ultrastructure or skin denticle morphology. However, we found that the elevated pCO(2) group buffered internal acidosis via HCO3- accumulation with an associated increase in Na+, indicating that the blood chemistry remained altered despite the long acclimation period. The elevated pCO(2) group also exhibited a shift in their nocturnal swimming pattern from a pattern of many starts and stops to more continuous swimming. Although CO2-exposed teleost fishes can display reduced behavioural asymmetry (lateralization), the CO2-exposed sharks showed increased lateralization. These behavioural effects may suggest that elasmobranch neurophysiology is affected by CO2, as in some teleosts, or that the sharks detect CO2 as a constant stressor, which leads to altered behaviour. The potential direct effects of ocean acidification should henceforth be considered when assessing future anthropogenic effects on sharks.
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| 26. |
- Gräns, Albin, 1979, et al.
(författare)
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Aerobic scope fails to explain the detrimental effects on growth resulting from warming and elevated CO2 in Atlantic halibut
- 2014
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 217:5, s. 711-717
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Tidskriftsartikel (refereegranskat)abstract
- As a consequence of increasing atmospheric CO2, the world's oceans are becoming warmer and more acidic. Whilst the ecological effects of these changes are poorly understood, it has been suggested that fish performance including growth will be reduced mainly as a result of limitations in oxygen transport capacity. Contrary to the predictions given by the oxygen- and capacity-limited thermal tolerance hypothesis, we show that aerobic scope and cardiac performance of Atlantic halibut (Hippoglossus hippoglossus) increase following 14–16 weeks exposure to elevated temperatures and even more so in combination with CO2-acidified seawater. However, the increase does not translate into improved growth, demonstrating that oxygen uptake is not the limiting factor for growth performance at high temperatures. Instead, long-term exposure to CO2-acidified seawater reduces growth at temperatures that are frequently encountered by this species in nature, indicating that elevated atmospheric CO2 levels may have serious implications on fish populations in the future.
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| 27. |
- Hernroth, Bodil, 1951, et al.
(författare)
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Simulated climate change causes immune suppression and protein damage in the crustacean Nephrops norvegicus
- 2012
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Ingår i: Fish & Shellfish Immunology. - : Elsevier BV. - 1050-4648 .- 1095-9947. ; 33:5, s. 1095-1101
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Tidskriftsartikel (refereegranskat)abstract
- Rising atmospheric carbon dioxide concentration is causing global warming, which affects oceans by elevating water temperature and reducing pH. Crustaceans have been considered tolerant to ocean acidification because of their retained capacity to calcify during subnormal pH. However, we report here that significant immune suppression of the Norway lobster, Nephrops norvegicus, occurs after a 4-month exposure to ocean acidification (OA) at a level predicted for the year 2100 (hypercapnic seawater with a pH lowered by 0.4 units). Experiments carried out at different temperatures (5, 10, 12, 14, 16, and 18 °C) demonstrated that the temperature within this range alone did not affect lobster immune responses. In the OA-treatment, hemocyte numbers were reduced by almost 50% and the phagocytic capacity of the remaining hemocytes was inhibited by 60%. The reduction in hemocyte numbers was not due to increased apoptosis in hematopoetic tissue. Cellular responses to stress were investigated through evaluating advanced glycation end products (AGE) and lipid oxidation in lobster hepatopancreata, and OA-treatment was shown to significantly increase AGEs', indicating stress-induced protein alterations. Furthermore, the extracellular pH of lobster hemolymph was reduced by approximately 0.2 units in the OA-treatment group, indicating either limited pH compensation or buffering capacity. The negative effects of OA-treatment on the nephropidae immune response and tissue homeostasis were more pronounced at higher temperatures (12–18 °C versus 5 °C), which may potentially affect disease severity and spread. Our results signify that ocean acidification may have adverse effects on the physiology of lobsters, which previously had been overlooked in studies of basic parameters such as lobster growth or calcification.
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| 28. |
- Jutfelt, Fredrik, 1975, et al.
(författare)
-
Atlantic cod actively avoid CO2 and predator odour, even after long-term CO2 exposure
- 2013
-
Ingår i: Frontiers in Zoology. - : Springer Science and Business Media LLC. - 1742-9994. ; 10:81
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction: The rising atmospheric CO2 level is continuously driving the dissolution of more CO2 into the oceans, and some emission scenarios project that the surface waters may reach 1000 mu atm by the end of the century. It is not known if fish can detect moderately elevated CO2 levels, and if they avoid areas with high CO2. If so, avoidance behaviour to water with high CO2 could affect movement patterns and migrations of fish in the future. It is also being increasingly recognized that fish behaviour can be altered by exposure to CO2. Therefore this study investigated how long-term exposure to elevated pCO(2) affects predator avoidance and CO2 avoidance in juvenile Atlantic cod (Gadus morhua). The fish were exposed to control water or CO2-enriched water (1000 mu atm) for six weeks before being subjected to tests of behaviour. Results: Despite long term exposure to elevated pCO(2) the cod still strongly avoided the smell of a predator. These data are surprising because several coral reef fish have demonstrated reversal of olfactory responses after CO2 exposure, turning avoidance of predator cues into preference for predator cues. Fish from both treatment groups also demonstrated strong avoidance of CO2 when presented with the choice of control or CO2-acidified water, indicating that habituation to the CO2 sensory stimuli is negligible. Conclusions: As Atlantic cod maintained normal behavioural responses to olfactory cues, they may be tolerant to CO2-induced behavioural changes. The results also suggest that despite the long-term exposure to CO2-acidified water, the fish still preferred the control water over CO2-acidified water. Therefore, in the future, fish may alter their movements and migrations in search of waters with a lower CO2 content.
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| 29. |
- Jutfelt, Fredrik, 1975, et al.
(författare)
-
Behavioural Disturbances in a Temperate Fish Exposed to Sustained High-CO2 Levels
- 2013
-
Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:6
-
Tidskriftsartikel (refereegranskat)abstract
- As atmospheric CO2 levels rise, the CO2 concentration in ocean surface waters increases through a process commonly referred to as ocean acidification. Recently, surprising behavioural modifications has been detected in the early life stages of tropical coral reef fish exposed to ocean acidification-relevant CO2 concentrations, but it has been unclear if this effect could occur in temperate waters. Here we show several severe behavioural disturbances, including effects on boldness, exploratory behaviour, lateralisation, and learning in a temperate fish, the three-spined stickleback (Gasterosteus aculeatus). The behavioural effects were consistent throughout the exposure period and increased in effect size with exposure time. We observed the effects on adult sticklebacks, a species known to be tolerant to other environmental stressors. Our findings suggest that behavioural abnormalities that stem from CO2 exposure are not restricted to sensitive tropical species or early life stages and may therefore affect fish on a global scale. The severity of disturbances and the possibility of a serious behavioural problem for fish across the globe is cause for concern.
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| 30. |
- Jutfelt, Fredrik, et al.
(författare)
-
Brain cooling marginally increases acute upper thermal tolerance in Atlantic cod
- 2019
-
Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 222:19
-
Tidskriftsartikel (refereegranskat)abstract
- Physiological mechanisms determining thermal limits in fishes are debated but remain elusive. It has been hypothesised that motor function loss, observed as loss of equilibrium during acute warming, is due to direct thermal effects on brain neuronal function. To test this, we mounted cooling plates on the heads of Atlantic cod (Gadus morhua) and quantified whether local brain cooling increased whole-organism acute upper thermal tolerance. Brain cooling reduced brain temperature by 2-6 °C below ambient water temperature and increased thermal tolerance by 0.5 and 0.6 °C on average relative to instrumented and uninstrumented controls, respectively, suggesting that direct thermal effects on brain neurons may contribute to setting upper thermal limits in fish. However, the improvement in thermal tolerance with brain cooling was small relative to the difference in brain temperature, demonstrating that other mechanisms (e.g. failure of spinal and peripheral neurons, or muscle) may also contribute to controlling acute thermal tolerance.
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| 31. |
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| 32. |
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| 33. |
- Jutfelt, Fredrik, 1975, et al.
(författare)
-
Juvenile Atlantic cod behavior appears robust to near-future CO2 levels
- 2015
-
Ingår i: Frontiers in Zoology. - : Springer Science and Business Media LLC. - 1742-9994. ; 12:11
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Ocean acidification caused by the anthropogenic release of CO2 is considered a major threat to marine ecosystems. One unexpected impact of elevated water CO2 levels is that behavioral alterations may occur in tropical reef fish and certain temperate fish species. These effects appear to alter many different types of sensory and cognitive functions; if widespread and persistent, they have the potential to cause ecosystem changes. Methods: We investigated whether economically and ecologically important Atlantic cod also display behavioral abnormalities by exposing 52 juvenile cod to control conditions (500 mu atm, duplicate tanks) or an end-of-the-century ocean acidification scenario (1000 mu atm, duplicate tanks) for one month, during which time the fish were examined for a range of behaviors that have been reported to be affected by elevated CO2 in other fish. The behaviors were swimming activity, as measured by number of lines crossed per minute, the emergence from shelter, determined by how long it took the fish to exit a shelter after a disturbance, relative lateralization (a measure of behavioral turning side preference), and absolute lateralization (the strength of behavioral symmetry). Results: We found no effect of CO2 treatment on any of the four behaviors tested: activity (F = 1.61, p = 0.33), emergence from shelter (F = 0.13, p = 0.76), relative lateralization (F = 2.82, p = 0.50), and absolute lateralization (F = 0.80, p = 0.26). Conclusion: Our results indicate that the behavior of Atlantic cod could be resilient to the impacts of near-future levels of water CO2.
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| 34. |
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| 35. |
- Jutfelt, Fredrik, 1975, et al.
(författare)
-
Parr-smolt transformation and dietary vegetable lipids affect intestinal nutrient uptake, barrier function and plasma cortisol levels in Atlantic salmon
- 2007
-
Ingår i: Aquaculture. - : Elsevier BV. - 0044-8486. ; 273:2-3, s. 298-311
-
Tidskriftsartikel (refereegranskat)abstract
- For Atlantic salmon, the gastrointestinal tract is the site of food digestion and nutrient uptake, a regulatory site for ion and water balance as well as a barrier against invading pathogens. During the parr–smolt transformation and subsequent seawater (SW) transfer, major changes occur in the intestine. A global shortage of fish oils (FO) for feed production is estimated to appear within a few years, and vegetable oils (VO) are being considered as alternatives for FO in fish feed production. However, VO influences the fatty acid composition of the polar lipids of cell membranes in the intestine which can disturb intestinal functions. A VO-based diet during the parr–smolt transformation, which is a sensitive developmental period, may cause adverse effects. Therefore, Atlantic salmon parr were fed either sunflower oil (SO) or FO as the major lipid source during out-of-season light controlled parr–smolt transformation. At three time points gill Na+,K+-ATPase activity and plasma levels of cortisol and growth hormone were assessed. Intestinal epithelia were sampled for assessment of nutrient absorption and bacterial translocation using an Ussing chamber in vitro system. While both dietary groups showed plasma hormone profiles indicative of successful parr–smolt transformation, the SO-fed fish had consistently increased cortisol levels compared to the FO-fed fish. Translocation of pathogenic bacteria increased, probably due to disturbed barrier functions, during the parr–smolt transformation. However, the fish fed the SO-diet maintained a higher barrier function compared to FO-fed fish, an effect that may be beneficial to these fish. Nutrient uptake was less affected by smoltification. Fish fed the SO-diet had higher uptake rates of amino acids and free fatty acids during mid-smoltification than fish fed the FO-diet. The combined effects of barrier function and nutrient uptake may suggest a positive effect of including vegetable lipids in the diet during the parr–smolt transformation. However, the vegetable lipid diet also seemed to act as a stressor and elevated the basal cortisol levels, which may be of concern in the context of general fish health and welfare.
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| 36. |
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| 37. |
- Jutfelt, Fredrik, 1975
(författare)
-
The intestinal epithelium of salmonids : transepithelial transport, barrier function and bacterial interactions
- 2006
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The salmonid intestinal epithelium is important for growth and health of the fish. The epithelium is exposed to a multitude of internal and external factors that can influence its function. During the parr-smolt transformation and subsequent seawater transfer, the epithelium adapts for an osmoregulatory role and the fish starts drinking seawater (SW). Endocrine signals increases the intestinal water uptake partly through an up-regulation of Na+,K+-ATPase activity. It is shown that the epithelial paracellular permeability decrease concurrent with the increase in water transport, suggesting that water flow is directed from a paracellular to a more transcellular route. The rational for this could be the increase in epithelial exposure to the environment at SW entrance. Tightening the paracellular route could be a mechanism to reduce paracellular transfer of harmful substances and pathogens. A major salmonid pathogen is the bacterium Aeromonas salmonicida, which cause losses in both aquaculture and in wild populations. It is not known, however, by which route the A. salmonicida enters the fish. A. salmonicida has been positively demonstrated in the intestinal lumen but it has been controversial whether or not the bacteria cross the epithelial barriers. It is demonstrated that A. salmonicida can translocate across the intestinal barrier, indicating the intestine as a functional route for bacterial infection in salmonids. It is concluded that A. salmonicida employs many virulence mechanisms, such as exotoxins, endotoxin and cell bound factors, to disrupts epithelial morphology and function and promote translocation. During the later phases of parr-smolt transformation the epithelial barrier integrity decreased and translocation of pathogens increased. The increased disease susceptibility during this life stage could thus partly be caused by a decreased barrier function. Vegetable lipids are used as replacement for fish oil in salmonid aquaculture, but there are concerns about how the new diets affect the intestinal epithelium. The epithelial functions presently investigated indicate a slight increase in permeability, supporting earlier histological reports of epithelial disruptions but not to the same extent. Nutrient uptake and barrier function during the parr-smolt transformation was significantly improved by a vegetable lipid-containing diet, indicating that this inclusion may be beneficial in the freshwater (FW) stage. The fatty acid profile of the natural diet for salmonids in FW is more similar to a blend of vegetable oils than to the profile of marine feed ingredients, routinely used in salmonid aquaculture. This may be the rationale for the positive effects. Salmon fed sunflower oil, however, showed long term elevation of plasma cortisol levels indicating a chronic stress. As chronic stress is known to depress immune function, specific vegetable lipids potentially stressful to the fish may also affect their health and welfare. Thus, while vegetable lipids at certain life stages are feasible substitutes for fish oil, possible long term stress effects by vegetable oils should be considered. In conclusion, the salmonid intestinal epithelium is a sensitive and dynamic tissue which is affected by external factors, such as pathogen bacteria, environment and diet, but which also can be endogenously regulated to compensate for this disturbance.
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| 38. |
- Jutfelt, Fredrik, 1975, et al.
(författare)
-
The involvement of Aeromonas salmonicida virulence factors in bacterial translocation across the rainbow trout, Oncorhynchus mykiss (Walbaum), intestine.
- 2008
-
Ingår i: Journal of fish diseases. - : Wiley. - 0140-7775. ; 31:2, s. 141-51
-
Tidskriftsartikel (refereegranskat)abstract
- The pathogenic bacterium Aeromonas salmonicida is the causative agent of furunculosis, a lethal disease in salmonids. The mode of lateral transmission has not been conclusively defined, but A. salmonicida is able to translocate across the intestinal epithelium of salmonids, making the intestinal route a probable candidate. This study investigated some of the virulence mechanisms used by the bacteria to promote translocation. Intestinal segments were placed in modified Ussing chambers to investigate epithelial functions during exposure to bacterial factors. The factors were: extracellular products (ECP), lipopolysaccharide (LPS) or live or heat-inactivated A. salmonicida. Fluorescein isothiocynate (FITC)-labelling enabled detection of translocated bacteria by fluorometry. Live A. salmonicida translocated to a greater degree than heat-inactivated bacteria, suggesting that the bacteria utilize a heat sensitive surface-bound virulence factor which promotes translocation. The epithelium was negatively affected by ECP, manifested as decreased net ion transport, indicating a disturbance in ion channels or cell metabolism. LPS did not affect the epithelium in vitro when administered on the luminal side of the intestinal segment, but significantly increased epithelial translocation of fluorescent bacterial-sized microspheres when administered on the serosal side. This is suggested to be caused by increased transcellular transport, as the paracellular permeability was unaffected indicating maintained epithelial integrity.
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| 39. |
- Jutfelt, Fredrik, 1975, et al.
(författare)
-
Translocation of viable Aeromonas salmonicida across the intestine of rainbow trout, Oncorhynchus mykiss (Walbaum)
- 2006
-
Ingår i: Journal of Fish Diseases. - : Wiley. - 0140-7775 .- 1365-2761. ; 29:5, s. 255-262
-
Tidskriftsartikel (refereegranskat)abstract
- The pathogenic bacterium Aeromonas salmonicida is the causative agent of the destructive disease furunculosis in salmonids. Horizontal transmission in salmonids has been suggested to occur via the skin, gills and/or intestine. Previous reports are contradictory regarding the role of the intestine as a route of infection. The present study therefore investigates the possibility of bacterial translocation across intestinal epithelia using Ussing chamber technology, in vitro. Intestinal segments were exposed for 90 min to fluorescein isothiocyanate-labelled pathogenic A. salmonicida. Sampling from the serosal side of the Ussing chambers showed that bacteria were able to translocate across the intestinal epithelium in both the proximal and distal regions. Plating and subsequent colony counting showed that the bacteria were viable after translocation. During the 90 min exposure to A. salmonicida, the intestinal segments maintained high viability as measured by electrical parameters. The distal region responded to bacterial exposure by increasing the electrical resistance, indicating an increased mucus secretion. This study thus demonstrates translocation of live A. salmonicida through the intestinal epithelium of rainbow trout, suggesting that the intestine is a possible route of infection in salmonids.
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| 40. |
- Jutfelt, Fredrik, 1975, et al.
(författare)
-
Two-current choice flumes for testing avoidance and preference in aquatic animals
- 2017
-
Ingår i: Methods in Ecology and Evolution. - : Wiley. - 2041-210X. ; 8:3, s. 379-390
-
Tidskriftsartikel (refereegranskat)abstract
- Aquatic chemical ecology is an important and growing field of research that involves understanding how organisms perceive and respond to chemical cues in their environment. Research assessing the preference or avoidance of a water source containing specific chemical cues has increased in popularity in recent years, and a variety of methods have been described in the scientific literature. Two-current choice flumes have seen the greatest increase in popularity, perhaps because of their potential to address the broadest range of research questions. Here, we review the literature on two-current choice flumes and show that there is a clear absence of standardized methodologies that make comparisons across studies difficult. Some of the main issues include turbulent flows that cause mixing of cues, inappropriate size of choice arenas for the animals, short experiments with stressed animals, failure to report how experiment and researcher biases were eliminated, general underreporting of methodological details, underutilization of collected data and inappropriate data analyses. In this review, we present best practice guidelines on how to build, test and use two-current choice flumes to measure the behavioural responses of aquatic animals to chemical cues, and provide blueprints for flume construction. The guidelines include steps that can be taken to avoid problems commonly encountered when using two-current choice flumes and analysing the resulting data. This review provides a set of standards that should be followed to ensure data quality, transparency and replicability in future studies in this field.
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| 41. |
- Jutfelt, Fredrik, et al.
(författare)
-
Two-current choice flumes for testing avoidance and preference in aquatic animals
- 2017
-
Ingår i: Methods in Ecology and Evolution. - : John Wiley & Sons. - 2041-210X. ; 8:3, s. 379-390
-
Forskningsöversikt (refereegranskat)abstract
- Aquatic chemical ecology is an important and growing field of research that involves understanding how organisms perceive and respond to chemical cues in their environment. Research assessing the preference or avoidance of a water source containing specific chemical cues has increased in popularity in recent years, and a variety of methods have been described in the scientific literature. Two-current choice flumes have seen the greatest increase in popularity, perhaps because of their potential to address the broadest range of research questions.Here, we review the literature on two-current choice flumes and show that there is a clear absence of standardized methodologies that make comparisons across studies difficult. Some of the main issues include turbulent flows that cause mixing of cues, inappropriate size of choice arenas for the animals, short experiments with stressed animals, failure to report how experiment and researcher biases were eliminated, general underreporting of methodological details, underutilization of collected data and inappropriate data analyses.In this review, we present best practice guidelines on how to build, test and use two-current choice flumes to measure the behavioural responses of aquatic animals to chemical cues, and provide blueprints for flume construction. The guidelines include steps that can be taken to avoid problems commonly encountered when using two-current choice flumes and analysing the resulting data.This review provides a set of standards that should be followed to ensure data quality, transparency and replicability in future studies in this field.
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| 42. |
- Knudsen, David, et al.
(författare)
-
Dietary soya saponins increase gut permeability and play a key role in the onset of soyabean-induced enteritis in Atlantic salmon ( Salmo salar L.).
- 2008
-
Ingår i: The British journal of nutrition. - 0007-1145. ; 100:1, s. 120-9
-
Tidskriftsartikel (refereegranskat)abstract
- Saponins are naturally occurring amphiphilic molecules and have been associated with many biological activities. The aim of the present study was to investigate whether soya saponins trigger the onset of soyabean-induced enteritis in Atlantic salmon (Salmo salar L.), and to examine if dietary soya saponins increase the epithelial permeability of the distal intestine in Atlantic salmon. Seven experimental diets containing different levels of soya saponins were fed to seawater-adapted Atlantic salmon for 53 d. The diets included a fishmeal-based control diet, two fishmeal-based diets with different levels of added soya saponins, one diet containing 25% lupin kernel meal, two diets based on 25% lupin kernel meal with different levels of added soya saponins, and one diet containing 25% defatted soyabean meal. The effect on intestinal morphology, intestinal epithelial permeability and faecal DM content was examined. Fish fed 25% defatted soyabean meal displayed severe enteritis, whereas fish fed 25% lupin kernel meal had normal intestinal morphology. The combination of soya saponins and fishmeal did not induce morphological changes but fish fed soya saponins in combination with lupin kernel meal displayed significant enteritis. Increased epithelial permeability was observed in fish fed 25% defatted soyabean meal and in fish fed soya saponin concentrate independent of the protein source in the feed. The study demonstrates that soya saponins, in combination with one or several unidentified components present in legumes, induce an inflammatory reaction in the distal intestine of Atlantic salmon. Soya saponins increase the intestinal epithelial permeability but do not, per se, induce enteritis.
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| 43. |
- Kreiss, C. M., et al.
(författare)
-
Ocean warming and acidification modulate energy budget and gill ion regulatory mechanisms in Atlantic cod (Gadus morhua)
- 2015
-
Ingår i: Journal of Comparative Physiology B-Biochemical Systemic and Environmental Physiology. - : Springer Science and Business Media LLC. - 0174-1578. ; 185:7, s. 767-781
-
Tidskriftsartikel (refereegranskat)abstract
- Ocean warming and acidification are threatening marine ecosystems. In marine animals, acidification is thought to enhance ion regulatory costs and thereby baseline energy demand, while elevated temperature also increases baseline metabolic rate. Here we investigated standard metabolic rates (SMR) and plasma parameters of Atlantic cod (Gadus morhua) after 3-4 weeks of exposure to ambient and future PCO2 levels (550, 1200 and 2200 A mu atm) and at two temperatures (10, 18 A degrees C). In vivo branchial ion regulatory costs were studied in isolated, perfused gill preparations. Animals reared at 18 A degrees C responded to increasing CO2 by elevating SMR, in contrast to specimens at 10 A degrees C. Isolated gills at 10 A degrees C and elevated PCO2 (a parts per thousand yen1200 A mu atm) displayed increased soft tissue mass, in parallel to increased gill oxygen demand, indicating an increased fraction of gill in whole animal energy budget. Altered gill size was not found at 18 A degrees C, where a shift in the use of ion regulation mechanisms occurred towards enhanced Na+/H+-exchange and HCO3 (-) transport at high PCO2 (2200 A mu atm), paralleled by higher Na+/K+-ATPase activities. This shift did not affect total gill energy consumption leaving whole animal energy budget unaffected. Higher Na+/K+-ATPase activities in the warmth might have compensated for enhanced branchial permeability and led to reduced plasma Na+ and/or Cl- concentrations and slightly lowered osmolalities seen at 18 A degrees C and 550 or 2200 A mu atm PCO2 in vivo. Overall, the gill as a key ion regulation organ seems to be highly effective in supporting the resilience of cod to effects of ocean warming and acidification.
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| 44. |
- Krång, Anna Sara, 1972, et al.
(författare)
-
Combinational effects of climate derived ocean acidification, hypoxia and manganese on food search behavior and CO2 avoidance in the economically and ecologically important marine crustacean Nephrops norvegicus
- 2014
-
Ingår i: 10th International Conference on Lobster Biology and Management. Lobsters in a Changing Climate. Cancún, México, May 18–23, 2014.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Marine ecosystems face several environmental changes in the future. Rising atmospheric CO2 levels increase the ocean CO2 concentrations by a process known as ocean acidification. This is of great concern for marine organisms and yet we know very little about the combined effects of ocean acidification and other stressors such as spreading of oxygen depleted (hypoxic) areas. The Norway lobster, Nephrops norvegicus,is one of the commercially most important shellfish species in Europe. It is found on coastal soft bottom sediments that are subjected to periodic hypoxia. Hypoxia may in turn lead to release of manganese from the sediment, which is accumulated in benthic organisms. Here we investigated behavioral effects on N. norvegicus after long-term exposure to elevated CO2, at concentrations postulated for year 2100, but also the combinational effect of elevated CO2 and hypoxia and manganese. We show several behavioral disturbances, including effects on food recognition, food search and CO2 avoidance. Our results are compared with CO2 induced behavioral disturbances previous found in fish.
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| 45. |
- Kullgren, Andreas, 1977, et al.
(författare)
-
The impact of temperature on the metabolome and endocrine metabolic signals in Atlantic salmon (Salmo salar)
- 2013
-
Ingår i: Comparative Biochemistry and Physiology A. - : Elsevier BV. - 1095-6433 .- 1531-4332. ; 164:1, s. 44-53
-
Tidskriftsartikel (refereegranskat)abstract
- The aim was to elucidate the effects of elevated temperature on growth performance, growth- and appetite-regulating hormones and metabolism in Atlantic salmon, Salmo salar. Post-smolts in seawater (average mass 175 g) that had been reared at 12 °C were kept at three temperatures (8, 12 and 18 °C) and sampled after one and three months. After three months, the fish kept in 18 °C had decreased growth rate and condition factor, and elevated plasma levels of growth hormone (GH) and leptin, compared with fish kept at the lower temperatures. Food conversion efficiency was also decreased at 18 °C, while at the same time protein uptake was improved and thus was not a limiting mechanism for growth. Redistribution of energy stores in fish at the highest temperature is evident as a preference of maintaining length growth during times of limited energy availability. NMR-based metabolomics analyses of plasma revealed that several metabolites involved in energy metabolism were negatively affected by temperature in the upper temperature range of Atlantic salmon. Specifically, the high temperature induced a decline of several amino acids (glutamine, tyrosine and phenylalanine) and a shift in lipid metabolism. It appears likely that the decreased food intake at the highest temperature is linked to an anorexigenic function of leptin, but also that the decreased food intake, feed conversion efficiency and condition factor can be linked to changes in GH endocrinology.
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| 46. |
- Lai, F., et al.
(författare)
-
Altered neurotransmitter function in CO2-exposed stickleback (Gasterosteus aculeatus): A temperate model species for ocean acidification research
- 2015
-
Ingår i: Conservation Physiology. - : Oxford University Press (OUP). - 2051-1434. ; 3:1
-
Tidskriftsartikel (refereegranskat)abstract
- Studies on the consequences of ocean acidification for the marine ecosystem have revealed behavioural changes in coral reef fishes exposed to sustained near-future CO2 levels. The changes have been linked to altered function of GABAergic neurotransmitter systems, because the behavioural alterations can be reversed rapidly by treatment with the GABAA receptor antagonist gabazine. Characterization of the molecular mechanisms involved would be greatly aided if these can be examined in a well-characterized model organism with a sequenced genome. It was recently shown that CO2-induced behavioural alterations are not confined to tropical species, but also affect the three-spined stickleback, although an involvement of the GABAA receptor was not examined. Here, we show that loss of lateralization in the stickleback can be restored rapidly and completely by gabazine treatment. This points towards a worrying universality of disturbed GABAA function after high-CO2 exposure in fishes from tropical to temperate marine habitats. Importantly, the stickleback is a model species with a sequenced and annotated genome, which greatly facilitates future studies on underlying molecular mechanisms. © The Author 2015.
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| 47. |
- Morgan, Rachael, et al.
(författare)
-
Are model organisms representative for climate change research? : Testing thermal tolerance in wild and laboratory zebrafish populations
- 2019
-
Ingår i: Conservation Physiology. - : Oxford University Press. - 2051-1434. ; 7:1
-
Tidskriftsartikel (refereegranskat)abstract
- Model organisms can be useful for studying climate change impacts, but it is unclear whether domestication to laboratory conditions has altered their thermal tolerance and therefore how representative of wild populations they are. Zebrafish in the wild live in fluctuating thermal environments that potentially reach harmful temperatures. In the laboratory, zebrafish have gone through four decades of domestication and adaptation to stable optimal temperatures with few thermal extremes. If maintaining thermal tolerance is costly or if genetic traits promoting laboratory fitness at optimal temperature differ from genetic traits for high thermal tolerance, the thermal tolerance of laboratory zebrafish could be hypothesized to be lower than that of wild zebrafish. Furthermore, very little is known about the thermal environment of wild zebrafish and how close to their thermal limits they live. Here, we compared the acute upper thermal tolerance (critical thermal maxima; CTmax) of wild zebrafish measured on-site in West Bengal, India, to zebrafish at three laboratory acclimation/domestication levels: wild-caught, F-1 generation wild-caught and domesticated laboratory AB-WT line. We found that in the wild, CTmax increased with increasing site temperature. Yet at the warmest site, zebrafish lived very close to their thermal limit, suggesting that they may currently encounter lethal temperatures. In the laboratory, acclimation temperature appeared to have a stronger effect on CTmax than it did in the wild. The fish in the wild also had a 0.85-1.01 degrees C lower CTmax compared to all laboratory populations. This difference between laboratory-held and wild populations shows that environmental conditions can affect zebrafish's thermal tolerance. However, there was no difference in CTmax between the laboratory-held populations regardless of the domestication duration. This suggests that thermal tolerance is maintained during domestication and highlights that experiments using domesticated laboratory-reared model species can be appropriate for addressing certain questions on thermal tolerance and global warming impacts.
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| 48. |
- Morgan, Rachael, et al.
(författare)
-
Reduced physiological plasticity in a fish adapted to stable temperatures
- 2022
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - 0027-8424 .- 1091-6490. ; 119
-
Tidskriftsartikel (refereegranskat)abstract
- Plasticity can allow organisms to maintain consistent performance across a wide range of environmental conditions. However, it remains largely unknown how costly plasticity is and whether a trade-off exists between plasticity and performance under optimal conditions. Biological rates generally increase with temperature, and to counter that effect, fish use physiological plasticity to adjust their biochemical and physiological functions. Zebrafish in the wild encounter large daily and seasonal temperature fluctuations, suggesting they should display high physiological plasticity. Conversely, laboratory zebrafish have been at optimal temperatures with low thermal fluctuations for over 150 generations. We treated this domestication as an evolution experiment and asked whether this has reduced the physiological plasticity of laboratory fish compared to their wild counterparts. We measured a diverse range of phenotypic traits, from gene expression through physiology to behavior, in wild and laboratory zebrafish acclimated to 15 temperatures from 10 °C to 38 °C. We show that adaptation to the laboratory environment has had major effects on all levels of biology. Laboratory fish show reduced plasticity and are thus less able to counter the direct effects of temperature on key traits like metabolic rates and thermal tolerance, and this difference is detectable down to gene expression level. Rapid selection for faster growth in stable laboratory environments appears to have carried with it a trade-off against physiological plasticity in captive zebrafish compared with their wild counterparts.
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| 49. |
- Niklasson, Lars, et al.
(författare)
-
Effects of Cortisol on the Intestinal Mucosal Immune Response during Cohabitant Challenge with IPNV in Atlantic Salmon (Salmo salar)
- 2014
-
Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 9:5
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Tidskriftsartikel (refereegranskat)abstract
- Infectious pancreatic necrosis virus (IPNV) causes high incidence of disease in salmonids during the first period after SW transfer. During this period as well as during periods of stress, cortisol levels increase and indications of a relationship between IPNV susceptibility and cortisol have been suggested. The intestine is an entry route and a target tissue for IPNV displaying severe enteritis and sloughing of the mucosa in infected fish. The mechanisms behind effects of the virus on the intestinal tissue and the impact of cortisol on the effect remain unclear. In the present study, Atlantic salmon post smolts treated with or without slow release cortisol implants were subjected to a cohabitant IPNV challenge. Analysis of genes and proteins related to the innate and acquired immune responses against virus was performed 6 days post-challenge using qPCR and immunohistochemistry. An increased mRNA expression of anti-viral cytokine interferon type I was observed in the proximal intestine and head kidney as a response to the viral challenge and this effect was suppressed by cortisol. No effect was seen in the distal intestine. T-cell marker CD3 as well as MHC-I in both intestinal regions and in the head kidney was down regulated at the mRNA level. Number of CD8 alpha lymphocytes decreased in the proximal intestine in response to cortisol. On the other hand, mRNA expression of Mx and IL-1 beta increased in the proximal intestine and head kidney in IPNV challenged fish in the presence of cortisol suggesting that the immune activation shifts in timing and response pathway during simulated stress. The present study clearly demonstrates that IPNV infection results in a differentiated epithelial immune response in the different intestinal regions of the Atlantic salmon. It also reveals that the epithelial immune response differs from the systemic, but that both are modulated by the stress hormone cortisol.
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- Norin, Tommy, et al.
(författare)
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Predator presence affects activity patterns but not food consumption or growth of juvenile corkwing wrasse (Symphodus melops)
- 2021
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Ingår i: Behavioral Ecology and Sociobiology. - : Springer. - 0340-5443 .- 1432-0762. ; 75:1
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Tidskriftsartikel (refereegranskat)abstract
- Indirect effects of predators can manifest themselves as changes in prey behaviour and physiology. Given that digestion requires energy, it has been suggested that prey will choose to eat smaller meals under predation risk to reserve a larger portion of the aerobic metabolic scope they have available for energetically demanding tasks more critical than digestion, such as escape. To test this prediction, we quantified food consumption and growth of juvenile corkwing wrasses (Symphodus melops) over 11 days in the presence or absence of a predator (Atlantic cod, Gadus morhua). We then quantified behaviour and food consumption of the same wrasses in behavioural arenas with a predator. All food consumption was examined in the context of the aerobic scope that would have been available during the digestive period. Overall, there was no effect of predator exposure on food consumption or growth, yet predator-exposed wrasses were more consistent in their daily food consumption, lending some support to our prediction of prey bet-hedging on meal size under predation risk. The lack of a clear pattern may have resulted from a relatively low percentage of aerobic scope (similar to 20-27%) being occupied by digestion, such that fish retained ample capacity for activities other than digestion. In the subsequent behavioural trials, predator-exposed wrasses were more active and spent more time near the cod than predator-naive wrasses, suggesting the former had habituated to predation threat and were more risk-taking. Our results highlight the complex and often counter-intuitive effects that predator presence can have on prey populations beyond direct consumption. Significance statement Predators affect the behaviour of prey species by simply being present in the environment. Such intimidation by predators can change activity patterns of prey and be as important as direct predation for ecosystem dynamics. However, compared to behavioural changes, we know little about how predators indirectly affect prey physiology. We investigated if fish deliberately eat less food when a predator is present, in order to retain sufficient physiological capacity for avoiding a potential attack, on top of the energetically costly process of digesting. While our study confirms that predator encounters reduce prey activity, prey fish appeared to rapidly habituate to predator presence and we did not see reduced food consumption in predator-exposed fish; these were, however, more consistent than unexposed fish in their daily food consumption, suggesting that fish may still be mindful about protecting their aerobic capacity under predation risk.
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