| 1. |
- Brijs, Jeroen, et al.
(författare)
-
Experimental manipulations of tissue oxygen supply do not affect warming tolerance of European perch
- 2015
-
Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 218, s. 2448-2454
-
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.
|
|
| 2. |
- Carney Almroth, Bethanie, 1974, et al.
(författare)
-
Warmer water temperature results in oxidative damage in an Antarctic fish, the bald notothen
- 2015
-
Ingår i: Journal of Experimental Marine Biology and Ecology. - : Elsevier BV. - 0022-0981 .- 1879-1697. ; 468, s. 130-137
-
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.
|
|
| 3. |
- Ekström, Andreas, 1979, et al.
(författare)
-
Cardiac oxygen limitation during an acute thermal challenge in the European perch: Effects of chronic environmental warming and experimental hyperoxia
- 2016
-
Ingår i: American Journal of Physiology. Regulatory Integrative and Comparative Physiology. - : American Physiological Society. - 0363-6119 .- 1522-1490. ; 311:2
-
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.
|
|
| 4. |
- 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.
|
|
| 5. |
- 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.
|
|
| 6. |
- 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.
|
|
| 7. |
- 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.
|
|
| 8. |
- Näslund, Joacim, 1985, et al.
(författare)
-
Behavioural responses to simulated bird attacks in marine three-spined sticklebacks after exposure to high CO2 levels
- 2015
-
Ingår i: Marine and Freshwater Research. - : CSIRO Publishing. - 1323-1650. ; 66:10, s. 877-885
-
Tidskriftsartikel (refereegranskat)abstract
- The rising partial pressure of CO2 (pCO(2)) in oceanic water, termed ocean acidification, is an impending threat to marine life and has previously been reported to affect several aspects of fish behaviour. We evaluated the behavioural response to a simulated avian predator attack and lateralisation in three-spined sticklebacks (Gasterosteus aculeatus) after 10 and 20 days of exposure to present day pCO(2) (400atm) or elevated pCO(2) (1000atm). We show that elevated pCO(2) lead to reduced behavioural lateralisation. However, no major differences in the sheltering response after an overhead avian attack were observed; fish from both treatments exhibited similar and strong responses. Compared with fish exposed to high pCO(2), the control fish took longer time to freeze (i.e. stop moving) after attack at Day 20 but not Day 10. The freezing duration was significantly reduced between Day 10 and Day 20 in elevated pCO(2), whereas no such reduction was observed in the control-group. However, no significant differences between treatment groups were detected at Day 20. These results demonstrate that behaviour is indeed altered by high CO2 levels, although the general responses to avian predation stimuli remain similar to those of unexposed fish, indicating that some predator avoidance behaviours of three-spined sticklebacks are robust to environmental disturbance.
|
|
| 9. |
- Sswat, Michael, et al.
(författare)
-
Food web changes under ocean acidification promote herring larvae survival
- 2018
-
Ingår i: Nature Ecology and Evolution. - : Springer Science and Business Media LLC. - 2397-334X. ; 2:5, s. 836-840
-
Tidskriftsartikel (refereegranskat)abstract
- © 2018 The Author(s). Ocean acidification - the decrease in seawater pH due to rising CO 2 concentrations - has been shown to lower survival in early life stages of fish and, as a consequence, the recruitment of populations including commercially important species. To date, ocean-acidification studies with fish larvae have focused on the direct physiological impacts of elevated CO 2 , but largely ignored the potential effects of ocean acidification on food web interactions. In an in situ mesocosm study on Atlantic herring (Clupea harengus) larvae as top predators in a pelagic food web, we account for indirect CO 2 effects on larval survival mediated by changes in food availability. The community was exposed to projected end-of-the-century CO 2 conditions (~760 μatm pCO 2 ) over a period of 113 days. In contrast with laboratory studies that reported a decrease in fish survival, the survival of the herring larvae in situ was significantly enhanced by 19 ± 2%. Analysis of the plankton community dynamics suggested that the herring larvae benefitted from a CO 2 -stimulated increase in primary production. Such indirect effects may counteract the possible direct negative effects of ocean acidification on the survival of fish early life stages. These findings emphasize the need to assess the food web effects of ocean acidification on fish larvae before we can predict even the sign of change in fish recruitment in a high-CO 2 ocean.
|
|
| 10. |
- Sswat, M., et al.
(författare)
-
Growth performance and survival of larval Atlantic herring, under the combined effects of elevated temperatures and CO2
- 2018
-
Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 13:1
-
Tidskriftsartikel (refereegranskat)abstract
- In the coming decades, environmental change like warming and acidification will affect life in the ocean. While data on single stressor effects on fish are accumulating rapidly, we still know relatively little about interactive effects of multiple drivers. Of particular concern in this context are the early life stages of fish, for which direct effects of increased CO2 on growth and development have been observed. Whether these effects are further modified by elevated temperature was investigated here for the larvae of Atlantic herring (Clupea harengus), a commercially important fish species. Over a period of 32 days, larval survival, growth in size and weight, and instantaneous growth rate were assessed in a crossed experimental design of two temperatures (10°C and 12°C) with two CO2 levels (400 μatm and 900 μatm CO2) at food levels mimicking natural levels using natural prey. Elevated temperature alone led to increased swimming activity, as well as decreased survival and instantaneous growth rate (Gi). The comparatively high sensitivity to elevated temperature in this study may have been influenced by low food levels offered to the larvae. Larval size, Gi and swimming activity were not affected by CO2, indicating tolerance of this species to projected "end of the century" CO2 levels. A synergistic effect of elevated temperature and CO2 was found for larval weight, where no effect of elevated CO2 concentrations was detected in the 12°C treatment, but a negative CO2 effect was found in the 10°C treatment. Contrasting CO2 effects were found for survival between the two temperatures. Under ambient CO2 conditions survival was increased at 12°C compared to 10°C. In general, CO2 effects were minor and considered negligible compared to the effect of temperature under these mimicked natural food conditions. These findings emphasize the need to include biotic factors such as energy supply via prey availability in future studies on interactive effects of multiple stressors. © 2018 Sswat et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
|
|
