Andreas Ekström

Andreas Ekström
University of Gothenburg | GU · Department of Biological & Environmental Sciences

PhD in Comparative Zoophysiology and Ecophysiology

About

45
Publications
7,314
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751
Citations
Introduction
My research interests and experience are within the fields of comparative and cardiovascular physiology with a particular emphasis on ecophysiology. My primary focus is to study the relationship between cardiovascular performances and cardiac oxygen supply in fish in vivo, and the ability of fish to perform challenging tasks (e.g., swimming) whilst exposed to environmental stressors e.g., warming and hypoxia.
Additional affiliations
May 2017 - March 2019
University of Gothenburg
Position
  • PostDoc Position
September 2012 - present
University of Gothenburg
Position
  • Lecturer
Education
September 2012 - May 2017
University of Gothenburg
Field of study
  • Cardiovascular physiology, comparative physiology and ecophysiology
August 2009 - July 2011
Linköping University
Field of study
  • Molecular genetics and physiology
August 2007 - July 2009
Linköping University
Field of study
  • Biology

Publications

Publications (45)
Chapter
The typical fish cardiovascular system comprises four major parts: a heart, blood vessels, blood, and control systems. Most water-breathing fishes have a closed, single-circuit circulatory system in which blood flows in a loop from the heart, through the gills, to the peripheral tissues, and back to the heart (Figure 10.1). Air-breathing fishes hav...
Article
Full-text available
The capacity to extract oxygen from the water, and the ability of the heart to drive tissue oxygen transport, are fundamental determinants of important life-history performance traits in fish. Cardiac performance is in turn dependent on the heart's own oxygen supply, which in some teleost species is partly delivered via a coronary circulation origi...
Article
Full-text available
When in seawater, rainbow trout (Oncorhynchus mykiss) drink to avoid dehydration and display stroke volume (SV) mediated elevations in cardiac output (CO) and an increased proportion of CO is diverted to the gastrointestinal tract as compared to when in freshwater. These cardiovascular alterations are associated with distinct reductions in systemic...
Article
Coronary arteriosclerosis is a common feature of both wild and farmed salmonid fishes and may be linked to stress-induced cardiac pathologies. Yet, the plasticity and capacity for long-term myocardial restructuring and recovery following a restriction in coronary blood supply is unknown. Here, we analyzed the consequences of acute (3 days) and chro...
Article
During spawning, adult Pacific salmonids ( Oncorhynchus spp . ) complete challenging upriver migrations during which energy and oxygen delivery must be partitioned into activities such as locomotion, maturation and spawning behaviours under the constraints of an individual's cardiac capacity. To advance our understanding of cardiac function in free...
Article
In fish, maximum O2 consumption rate (MO2max) and aerobic scope can be expanded following exhaustive exercise in hyperoxia; however, the mechanisms explaining this are yet to be identified. Here, in exhaustively exercised rainbow trout (Oncorhynchus mykiss), we assessed the influence of hyperoxia on MO2max, aerobic scope, cardiac function and blood...
Article
Full-text available
Tolerance to acute environmental warming in fish is partly governed by the functional capacity of the heart to increase systemic oxygen delivery at high temperatures. However, cardiac function typically deteriorates at high temperatures, due to declining heart rate and an impaired capacity to maintain or increase cardiac stroke volume, which in tur...
Article
Full-text available
Approximately half of all fishes have, in addition to the luminal venous O 2 supply, a coronary circulation supplying the heart with fully oxygenated blood. Yet, it is not fully understood how coronary O 2 delivery affects tolerance to environmental extremes such as warming and hypoxia. Hypoxia reduces arterial oxygenation, while warming increases...
Article
Full-text available
Few studies have addressed how reduced water salinity affects cardiovascular and metabolic function in marine euryhaline fishes, despite its relevance for predicting impacts of natural salinity variations and ongoing climate change on marine fish populations. Here, shorthorn sculpin (Myoxocephalus scorpius) were subjected to different durations of...
Article
Aquatic hypoxia will become increasingly prevalent in the future due to eutrophication combined with climate warming. While short-term warming typically constrains fish hypoxia tolerance, many fishes cope with warming by adjusting physiological traits through thermal acclimation. Yet, little is known about how such adjustments affect tolerance to h...
Article
Full-text available
Mitochondria are playing key roles in setting the thermal limits of fish, but how these organelles participate in selection mechanisms during extreme thermal events associated with climate warming in natural populations is unclear. Here, we investigated the thermal effects on mitochondrial metabolism, oxidative stress, and mitochondrial gene expres...
Article
Full-text available
Cardiovascular disease may pose a major threat to the health and welfare of farmed fish. By investigating a range of established cardiovascular disease indicators, we aimed to determine the prevalence, severity and consequences of this affliction in farmed rainbow trout (Oncorhynchus mykiss) from an open cage farm in the Baltic Sea, an open cage fa...
Article
Full-text available
Bio-logging devices can provide unique insights on the life of freely moving animals. However, implanting these devices often requires invasive surgery that causes stress and physiological side-effects. While certain medications in connection to surgeries have therapeutic capacity, others may have aversive effects. Here, we hypothesized that the co...
Article
Full-text available
Coronary perfusion and cardiac autonomic regulation may benefit myocardial oxygen delivery and thermal performance of the teleost heart, and thus influence whole animal heat tolerance. Yet, no study has examined how coronary perfusion affects cardiac output during warming in vivo. Moreover, while β-adrenergic stimulation could protect cardiac contr...
Article
Full-text available
Some evidence suggests that cardiac mitochondrial functions might be involved in the resilience of ectotherms such as fish to environmental warming. Here, we investigated the effects of acute and chronic changes in thermal regimes on cardiac mitochondrial plasticity and thermal sensitivity in perch (Perca fluviatilis) from an artificially heated ec...
Article
Full-text available
In seawater, rainbow trout (Oncorhynchus mykiss) drink and absorb water through the gastrointestinal tract to compensate for water passively lost to the hyperosmotic environment. Concomitantly, they exhibit elevated cardiac output and a doubling of gastrointestinal blood flow to provide additional O2 to the gut and increase convective flux of absor...
Article
It is well known that fish can learn to avoid angling gear after experiencing a catch‐and‐release event, that is, after a private hooking experience. However, the possible importance of social information cues and their influence on an individual's vulnerability to angling remains largely unexplored, that is, social experience of a conspecific capt...
Article
Full-text available
Greater salinity variations resulting from ongoing climate change requires consideration in conservation management as this may impact on the performance of aquatic organisms. Euryhaline fish exhibit osmoregulatory flexibility and can exploit a wide range of salinities. In seawater (SW), they drink and absorb water in the intestine, which is associ...
Article
Cardiac oxygenation is achieved via both coronary arterial and luminal venous oxygen supply routes in many fish species. However, the relative importance of these supplies for cardiac and aerobic metabolic performance is not fully understood. Here, we investigated how coronary artery ligation in rainbow trout (Oncorhynchus mykiss), implanted with h...
Article
Full-text available
The Commentary by Pörtner, Bock and Mark (Pörtner et al., 2017) elaborates on the oxygen- and capacity-limited thermal tolerance (OCLTT) hypothesis. Journal of Experimental Biology Commentaries allow for personal and controversial views, yet the journal also mandates that ‘opinion and fact must be clearly distinguishable’ (http://jeb.biologists.org...
Article
Stress and elevated cortisol levels are associated with pathological heart growth and cardiovascular disease in humans and other mammals. We recently established a link between heritable variation in post-stress cortisol production and cardiac growth also in salmonid fish. A conserved stimulatory effect of the otherwise catabolic steroid hormone co...
Article
Full-text available
Anadromy is a distinctive life-history strategy in fishes that has evolved independently many times. In an evolutionary context, the benefits of anadromy for a species or population must outweigh the costs and risks associated with the habitat switch. The migration of fish across the freshwater-ocean boundary coincides with potentially energeticall...
Article
Full-text available
Although the mitochondrial metabolism responses to warm acclimation have been widely studied in fish, the time course of this process is less understood. Here, we characterise changes of rainbow trout (Oncorhyncus mykiss) cardiac mitochondrial metabolism during acute warming from 10 to 16°C, and during the subsequent warm acclimation for 39 days (D...
Article
Full-text available
Cellular and mitochondrial metabolic capacity of the heart has been suggested to limit performance of fish at warm temperatures. We investigated this hypothesis by studying the effects of acute temperature increases (16, 23, 30, 32.5 and 36°C) on the thermal sensitivity of 10 key enzymes governing cardiac oxidative and glycolytic metabolism in two...
Article
Substantial increases in cardiac output (CO), stroke volume (SV) and gastrointestinal blood flow are essential for euryhaline rainbow trout (Oncorhyncus mykiss) osmoregulating in seawater. However, the underlying hemodynamic mechanisms responsible for these changes are unknown. By examining a range of circulatory and cardiac morphological variables...
Article
Substantial increases in cardiac output (CO), stroke volume (SV), and gastrointestinal blood flow are essential for euryhaline rainbow trout (Oncorhyncus mykiss) osmoregulation in seawater. However, the underlying hemodynamic mechanisms responsible for these changes are unknown. By examining a range of circulatory and cardiac morphological variable...
Article
Full-text available
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...
Article
Full-text available
Thermal plasticity of cardiorespiratory function allows ectotherms like fish to cope with seasonal temperature changes and is critical for resilience to climate change. Yet, the chronic thermal effects on cardiovascular homeostatic reflexes in fish are little understood although this may have important implications for physiological performance and...
Article
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...
Article
Full-text available
Understanding the resilience of aquatic ectothermic animals to climate warming has been hindered by the absence of experimental systems experiencing warming across relevant timescales (for example, decades). Here, we examine European perch (Perca fluviatilis, L.) from the Biotest enclosure, a unique coastal ecosystem that maintains natural thermal...
Data
Supplementary Figures 1-3 and Supplementary Tables 1-4.
Article
Increased gastrointestinal blood flow is essential for euryhaline fishes to maintain osmotic homeostasis during the initial phase of a transition from freshwater to seawater. However, the cardiorespiratory responses and hemodynamic changes required for a successful long-term transition to seawater remain largely unknown. In the present study, we si...
Article
Full-text available
Time course studies are critical to understand regulatory mechanisms and temporal constraints in ectothermic animals acclimating to warmer temperatures. Therefore, we investigated the dynamics of heart rate and its neuro-humoral control in rainbow trout (Onchorhynchus mykiss L.) acclimating to 16°C for 39 days after being acutely warmed from 9°C. R...
Article
The consequences of elevated temperature on body shape were investigated by comparing European perch Perca fluviatilis from the Forsmark area of the Baltic Sea to P. fluviatilis from a nearby Biotest enclosure. The Biotest is a man-made enclosure within the Baltic Sea that has received warm water from a nuclear power plant since 1980, resulting in...
Article
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 availa...
Article
Jorden med dess hav och sjöar håller på att bli varmare som en följd av den pågående klimatförändringen, men hur växelvarma djur som fisk kommer att svara på dessa förändringar är till stora delar okänt idag. I ett nystartat forskningsprojekt vid den uppvärmda Biotestsjön utanför Forsmarks kärnkraftverk undersöker nu forskare vad som händer med abb...
Poster
Fish, like all ectotherms, respond to acute warming by increased heart rate that may result in a decreased scope for heart rate (the difference between resting and maximal values). If given time to acclimate these acute effects are usually buffered by processes that reduce resting heart rate and restore the scope for heart rate. However, the time c...

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Projects

Projects (2)
Project
In this project, we investigate the relevance of the coronary circulation, which supplies the fish heart with oxygenated blood directly from the gills, for cardiac and whole animal performances in fish exposed to environmental stressors such as warming and hypoxia.
Project
Obtain physiological data enabling identification of cause and effect, Establish quantitative comparison of critical situations for farmed fish, Develop specific recommendations and basis for legislation to ensure animal welfare and improve future production and management systems.