Felix C Mark | Alfred Wegener Institute for Polar and Marine Research (original) (raw)
Papers by Felix C Mark
Oxygen equilibrium curves have been widely used to understand oxygen transport in numerous organi... more Oxygen equilibrium curves have been widely used to understand oxygen transport in numerous organisms. A major challenge has been to monitor oxygen binding characteristics and concomitant pH changes as they occur in vivo, in limited sample volumes. Here we report a technique allowing highly resolved and simultaneous monitoring of pH and blood pigment saturation in minute blood volumes. We equipped a gas diffusion chamber with a broad-range fibre-optic spectrophotometer and a micro-pH optode and recorded changes of pigment oxygenation along oxygen partial pressure (P O2) and pH gradients to test the setup. Oxygen binding parameters derived from measurements in only 15 μl of haemolymph from the cephalopod Octopus vulgaris showed low instrumental error (0.93%) and good agreement with published data. Broad-range spectra, each resolving 2048 data points, provided detailed insight into the complex absorbance characteristics of diverse blood types. After consideration of photobleaching and intrinsic fluorescence, pH optodes yielded accurate recordings and resolved a sigmoidal shift of 0.03 pH units in response to changing P O2 from 0 to 21 kPa. Highly resolved continuous recordings along pH gradients conformed to stepwise measurements at low rates of pH changes. In this study we showed that a diffusion chamber upgraded with a broad-range spectrophotometer and an optical pH sensor accurately characterizes oxygen binding with minimal sample consumption and manipulation. We conclude that the modified diffusion chamber is highly suitable for experimental biologists who demand high flexibility, detailed insight into oxygen binding as well as experimental and biological accuracy combined in a single setup.
Background: As the oceans are warming, fish stocks are moving with the water masses of their pref... more Background: As the oceans are warming, fish stocks are moving with the water masses of their preferred temperatures to stay within a physiologically optimal temperature range, provided further factors such as food availability and competition with other species allow for that. In response to this warming trend, the North Arctic stock of Atlantic cod (Gadus morhua) has also shifted spawning areas to the north and expanded its range into the Barents Sea. For the greatest part of the year, juvenile Atlantic cod are now frequently found in the coastal waters of Spitsbergen, with an as yet unclear outcome for the ecosystems species composition. Ocean acidification is an additional stressor developing in parallel to ongoing climate warming. Future impacts of ocean acidification on organisms and ecosystems are expected to be greatest in cold regions, while thermal tolerance windows are narrower and thus sensitivities to combined stressor effects are likely to be higher in cold-adapted polar compared to temperate species. The expected rise in carbon dioxide concentrations and temperature in the oceans may thus prove to be particularly threatening to Boreal and Arctic ecosystems. Some of the commercially most important fish species in the North Atlantic belong to the family of Gadidae, namely Atlantic cod, haddock, pollock, whiting, and Polar cod. Any shift in the population structure, caused by ocean acidification and warming (OAW) could thus have far reaching effects not only on the ecosystem itself but also on fisheries, and further, on aquaculture. The socio–economic consequences of such scenarios have not yet been evaluated. Methods: Within the German ocean acidification research programme BIOACID in its second phase from 2012-2015, we investigated how the combined effects of OAW affect different life stages and interactions between polar gadoid fish species and their prey. Objectives included addressing the question whether OAW affects interacting species differently due to divergent physiological optima and ranges, expressed in thermal tolerance windows and associated performance capacities and phenologies of specific life stages. Findings: I will report an overview of our collective efforts to identify fundamental mechanisms and unravel the connections between levels of biological organisation, from the genomic, molecular to cellular, individual and population level. Scopes for acclimation (physiology and behaviour) and adaptation (evolution) that together define species resilience were studied in various life stages (eggs, larvae, juveniles, adults) to identify the most sensitive one(s). We fed these data into socio-economic models to assess stock sensitivity and resilience to evaluate the possible consequences for fishery, aquaculture and last but not least, society.
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Apr 15, 2016
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Jul 28, 2016
The Journal of Experimental Biology, Aug 1, 2017
Hand in hand with ocean warming, ocean acidification is increasingly threatening life in the worl... more Hand in hand with ocean warming, ocean acidification is increasingly threatening life in the world’s oceans. This has sparked a growing number of studies of the effects of ocean acidification and warming on water breathing, ectotherm marine animals throughout the last decade. Amongst those species, fish have generally been regarded as reasonably tolerant towards ocean acidification, due to their well-developed capacities for ion- and pH-regulation. As a result, there are only a handful of physiological studies on ocean acidification effects in fish, and only very few studies have dealt with metabolic regulation at the cellular level. Yet, increased costs of acid-base regulation and metabolic rearrangements may either entail adjustments of the animal’s energy budget, leading to reduced growth and fecundity, or a higher total aerobic energy demand for the whole animal, reducing aerobic scope. In this presentation, I will focus on the current knowledge of the effects of ocean acidification and warming on the cellular metabolism and molecular regulation in various ontogenetic stages of marine fish of different biogeographic origin. I shall try to indicate capacities and bottlenecks for acclimation and discuss the consequences and limitations for the whole animal level with regard to population resilience.
The Journal of Experimental Biology, 2019
The world's oceans are acidifying and warming as a result of increasing atmospheric CO 2 concentr... more The world's oceans are acidifying and warming as a result of increasing atmospheric CO 2 concentrations. The thermal tolerance of fish greatly depends on the cardiovascular ability to supply the tissues with oxygen. The highly oxygen-dependent heart mitochondria thus might play a key role in shaping an organism's tolerance to temperature. The present study aimed to investigate the effects of acute and chronic warming on the respiratory capacity of European sea bass (Dicentrarchus labrax L.) heart mitochondria. We hypothesized that acute warming would impair mitochondrial respiratory capacity, but be compensated for by lifetime conditioning. Increasing P CO2 may additionally cause shifts in metabolic pathways by inhibiting several enzymes of the cellular energy metabolism. Among other shifts in metabolic pathways, acute warming of heart mitochondria of cold lifeconditioned fish increased leak respiration rate, suggesting a lower aerobic capacity to synthesize ATP with acute warming. However, thermal conditioning increased mitochondrial functionality, e.g. higher respiratory control ratios in heart mitochondria of warm life-conditioned compared with cold life-conditioned fish. Exposure to high P CO2 synergistically amplified the effects of acute and long-term warming, but did not result in changes by itself. This high ability to maintain mitochondrial function under ocean acidification can be explained by the fact that seabass are generally able to acclimate to a variety of environmental conditions. Improved mitochondrial energy metabolism after warm conditioning could be due to the origin of this species in the warm waters of the Mediterranean. Our results also indicate that seabass are not yet fully adapted to the colder temperatures in their northern distribution range and might benefit from warmer temperatures in these latitudes.
The efficiency and adaptive plasticity of mitochondrial metabolism is one of the key factors shap... more The efficiency and adaptive plasticity of mitochondrial metabolism is one of the key factors shaping organismal tolerance towards environmental change.We thus investigated the adaptive capacities of mitochondrial metabolism in Antarctic & Austral notothenioids (Nothothenia rossii, N. coriiceps & N. angustata) and temperate Sea Bass (Dicentrarchus labrax) with respect to some important factors that will influence the survival of marine life in the near future: global warming (elevated sea temperatures), ocean acidification (elevated CO2 levels) and hypoxia tolerance.We namely analysed the function and contribution of the single respiratory complexes to total mitochondrial metabolism, as well as membrane potential and proton leak. In all experiments, mitochondrial measurements were made under acute thermal challenges, compairing liver and heart mitochondria from either differently acclimated individuals (thermal acclimation, CO2 acclimation the combination thereof) or from individuals selected for a specific phenotypic trait (hypoxia tolerance in D. labrax).The implications of mitochondrial plasticity for long-term adaptation in a changing marine environment will be discussed.
Oxygen transport measurements have been widely used to explain evolutionary adaptation and perfor... more Oxygen transport measurements have been widely used to explain evolutionary adaptation and performance in fishes. Simultaneous measurements of blood pH and oxygen saturation are essential to understand oxygen transport as it occurs in vivo, but has been challenging to monitor with existing methods, particularly in minute blood volumes. We equipped a gas diffusion chamber with a broad-range fibre-optic spectrophotometer and a micro-pH optode and successfully recorded changes of pigment oxygenation and pH in only 15 µl of whole fish blood at 0°C. Highly resolved spectra ranging from 280 – 900 nm captured the complex absorbance features of Antarctic fish haemoglobin in response to changing oxygen and carbon dioxide partial pressures. After consideration of photobleaching and intrinsic fluorescence, pH optodes recorded pH shifts of 0.03 pH units. With this modified diffusion chamber experimental biologists are able to accurately characterize oxygen binding with minimal sample consumption and manipulation under diverse experimental settings.
This presentation addresses the role of mitochondria in non-genetic inheritance, shaping the adap... more This presentation addresses the role of mitochondria in non-genetic inheritance, shaping the adaptive potential of populations under a warming ocean scenario. In our study, we investigated transgenerational plasticity (TGP) to partition the relative contribution of maternal vs. paternal (additive genetic) effects to offspring body size (a key component of fitness). We investigated the potential physiological mechanisms underlying whole-organism growth/size responses by analysing mitochondrial capacities in the offspring of differently acclimated parental groups. Offspring body size of marine sticklebacks benefited from maternal TGP and were larger when reared at the respective mother’s acclimation temperature. This points at an involvement of mitochondrial metabolism, as in fish, mitochondria are almost exclusively inherited maternally. Indeed, mitochondrial capacities were significantly influenced by maternal temperature, reflecting the observed growth patterns and thus linking offspring body size to maternal inheritance of mitochondria. Maximum mitochondrial capacities differed depending on maternal temperature and offspring of warm acclimated mothers that were reared at warm temperatures showed full metabolic compensation with respect to heart mitochondrial capacities in comparison to the control groups. Our results for mitochondrial capacities between the different offspring groups suggest that mitochondria are a primary target for non-genetic transgenerational thermal compensation of metabolic rates in a changing climate, as an optimized energy metabolism will generate a higher scope for growth. Warm acclimated mothers adjust the metabolism of mitochondria that are inherited by offspring, and differences in mitochondrial capacities and efficiency underlie the differences observed in offspring growth.
Oxygen equilibrium curves have been widely used to understand oxygen transport in numerous organi... more Oxygen equilibrium curves have been widely used to understand oxygen transport in numerous organisms. A major challenge has been to monitor oxygen binding characteristics and concomitant pH changes as they occur in vivo, in limited sample volumes. Here we report a technique allowing highly resolved and simultaneous monitoring of pH and blood pigment saturation in minute blood volumes. We equipped a gas diffusion chamber with a broad-range fibre-optic spectrophotometer and a micro-pH optode and recorded changes of pigment oxygenation along oxygen partial pressure (P O2) and pH gradients to test the setup. Oxygen binding parameters derived from measurements in only 15 μl of haemolymph from the cephalopod Octopus vulgaris showed low instrumental error (0.93%) and good agreement with published data. Broad-range spectra, each resolving 2048 data points, provided detailed insight into the complex absorbance characteristics of diverse blood types. After consideration of photobleaching and intrinsic fluorescence, pH optodes yielded accurate recordings and resolved a sigmoidal shift of 0.03 pH units in response to changing P O2 from 0 to 21 kPa. Highly resolved continuous recordings along pH gradients conformed to stepwise measurements at low rates of pH changes. In this study we showed that a diffusion chamber upgraded with a broad-range spectrophotometer and an optical pH sensor accurately characterizes oxygen binding with minimal sample consumption and manipulation. We conclude that the modified diffusion chamber is highly suitable for experimental biologists who demand high flexibility, detailed insight into oxygen binding as well as experimental and biological accuracy combined in a single setup.
Background: As the oceans are warming, fish stocks are moving with the water masses of their pref... more Background: As the oceans are warming, fish stocks are moving with the water masses of their preferred temperatures to stay within a physiologically optimal temperature range, provided further factors such as food availability and competition with other species allow for that. In response to this warming trend, the North Arctic stock of Atlantic cod (Gadus morhua) has also shifted spawning areas to the north and expanded its range into the Barents Sea. For the greatest part of the year, juvenile Atlantic cod are now frequently found in the coastal waters of Spitsbergen, with an as yet unclear outcome for the ecosystems species composition. Ocean acidification is an additional stressor developing in parallel to ongoing climate warming. Future impacts of ocean acidification on organisms and ecosystems are expected to be greatest in cold regions, while thermal tolerance windows are narrower and thus sensitivities to combined stressor effects are likely to be higher in cold-adapted polar compared to temperate species. The expected rise in carbon dioxide concentrations and temperature in the oceans may thus prove to be particularly threatening to Boreal and Arctic ecosystems. Some of the commercially most important fish species in the North Atlantic belong to the family of Gadidae, namely Atlantic cod, haddock, pollock, whiting, and Polar cod. Any shift in the population structure, caused by ocean acidification and warming (OAW) could thus have far reaching effects not only on the ecosystem itself but also on fisheries, and further, on aquaculture. The socio–economic consequences of such scenarios have not yet been evaluated. Methods: Within the German ocean acidification research programme BIOACID in its second phase from 2012-2015, we investigated how the combined effects of OAW affect different life stages and interactions between polar gadoid fish species and their prey. Objectives included addressing the question whether OAW affects interacting species differently due to divergent physiological optima and ranges, expressed in thermal tolerance windows and associated performance capacities and phenologies of specific life stages. Findings: I will report an overview of our collective efforts to identify fundamental mechanisms and unravel the connections between levels of biological organisation, from the genomic, molecular to cellular, individual and population level. Scopes for acclimation (physiology and behaviour) and adaptation (evolution) that together define species resilience were studied in various life stages (eggs, larvae, juveniles, adults) to identify the most sensitive one(s). We fed these data into socio-economic models to assess stock sensitivity and resilience to evaluate the possible consequences for fishery, aquaculture and last but not least, society.
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Apr 15, 2016
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Jul 28, 2016
The Journal of Experimental Biology, Aug 1, 2017
Hand in hand with ocean warming, ocean acidification is increasingly threatening life in the worl... more Hand in hand with ocean warming, ocean acidification is increasingly threatening life in the world’s oceans. This has sparked a growing number of studies of the effects of ocean acidification and warming on water breathing, ectotherm marine animals throughout the last decade. Amongst those species, fish have generally been regarded as reasonably tolerant towards ocean acidification, due to their well-developed capacities for ion- and pH-regulation. As a result, there are only a handful of physiological studies on ocean acidification effects in fish, and only very few studies have dealt with metabolic regulation at the cellular level. Yet, increased costs of acid-base regulation and metabolic rearrangements may either entail adjustments of the animal’s energy budget, leading to reduced growth and fecundity, or a higher total aerobic energy demand for the whole animal, reducing aerobic scope. In this presentation, I will focus on the current knowledge of the effects of ocean acidification and warming on the cellular metabolism and molecular regulation in various ontogenetic stages of marine fish of different biogeographic origin. I shall try to indicate capacities and bottlenecks for acclimation and discuss the consequences and limitations for the whole animal level with regard to population resilience.
The Journal of Experimental Biology, 2019
The world's oceans are acidifying and warming as a result of increasing atmospheric CO 2 concentr... more The world's oceans are acidifying and warming as a result of increasing atmospheric CO 2 concentrations. The thermal tolerance of fish greatly depends on the cardiovascular ability to supply the tissues with oxygen. The highly oxygen-dependent heart mitochondria thus might play a key role in shaping an organism's tolerance to temperature. The present study aimed to investigate the effects of acute and chronic warming on the respiratory capacity of European sea bass (Dicentrarchus labrax L.) heart mitochondria. We hypothesized that acute warming would impair mitochondrial respiratory capacity, but be compensated for by lifetime conditioning. Increasing P CO2 may additionally cause shifts in metabolic pathways by inhibiting several enzymes of the cellular energy metabolism. Among other shifts in metabolic pathways, acute warming of heart mitochondria of cold lifeconditioned fish increased leak respiration rate, suggesting a lower aerobic capacity to synthesize ATP with acute warming. However, thermal conditioning increased mitochondrial functionality, e.g. higher respiratory control ratios in heart mitochondria of warm life-conditioned compared with cold life-conditioned fish. Exposure to high P CO2 synergistically amplified the effects of acute and long-term warming, but did not result in changes by itself. This high ability to maintain mitochondrial function under ocean acidification can be explained by the fact that seabass are generally able to acclimate to a variety of environmental conditions. Improved mitochondrial energy metabolism after warm conditioning could be due to the origin of this species in the warm waters of the Mediterranean. Our results also indicate that seabass are not yet fully adapted to the colder temperatures in their northern distribution range and might benefit from warmer temperatures in these latitudes.
The efficiency and adaptive plasticity of mitochondrial metabolism is one of the key factors shap... more The efficiency and adaptive plasticity of mitochondrial metabolism is one of the key factors shaping organismal tolerance towards environmental change.We thus investigated the adaptive capacities of mitochondrial metabolism in Antarctic & Austral notothenioids (Nothothenia rossii, N. coriiceps & N. angustata) and temperate Sea Bass (Dicentrarchus labrax) with respect to some important factors that will influence the survival of marine life in the near future: global warming (elevated sea temperatures), ocean acidification (elevated CO2 levels) and hypoxia tolerance.We namely analysed the function and contribution of the single respiratory complexes to total mitochondrial metabolism, as well as membrane potential and proton leak. In all experiments, mitochondrial measurements were made under acute thermal challenges, compairing liver and heart mitochondria from either differently acclimated individuals (thermal acclimation, CO2 acclimation the combination thereof) or from individuals selected for a specific phenotypic trait (hypoxia tolerance in D. labrax).The implications of mitochondrial plasticity for long-term adaptation in a changing marine environment will be discussed.
Oxygen transport measurements have been widely used to explain evolutionary adaptation and perfor... more Oxygen transport measurements have been widely used to explain evolutionary adaptation and performance in fishes. Simultaneous measurements of blood pH and oxygen saturation are essential to understand oxygen transport as it occurs in vivo, but has been challenging to monitor with existing methods, particularly in minute blood volumes. We equipped a gas diffusion chamber with a broad-range fibre-optic spectrophotometer and a micro-pH optode and successfully recorded changes of pigment oxygenation and pH in only 15 µl of whole fish blood at 0°C. Highly resolved spectra ranging from 280 – 900 nm captured the complex absorbance features of Antarctic fish haemoglobin in response to changing oxygen and carbon dioxide partial pressures. After consideration of photobleaching and intrinsic fluorescence, pH optodes recorded pH shifts of 0.03 pH units. With this modified diffusion chamber experimental biologists are able to accurately characterize oxygen binding with minimal sample consumption and manipulation under diverse experimental settings.
This presentation addresses the role of mitochondria in non-genetic inheritance, shaping the adap... more This presentation addresses the role of mitochondria in non-genetic inheritance, shaping the adaptive potential of populations under a warming ocean scenario. In our study, we investigated transgenerational plasticity (TGP) to partition the relative contribution of maternal vs. paternal (additive genetic) effects to offspring body size (a key component of fitness). We investigated the potential physiological mechanisms underlying whole-organism growth/size responses by analysing mitochondrial capacities in the offspring of differently acclimated parental groups. Offspring body size of marine sticklebacks benefited from maternal TGP and were larger when reared at the respective mother’s acclimation temperature. This points at an involvement of mitochondrial metabolism, as in fish, mitochondria are almost exclusively inherited maternally. Indeed, mitochondrial capacities were significantly influenced by maternal temperature, reflecting the observed growth patterns and thus linking offspring body size to maternal inheritance of mitochondria. Maximum mitochondrial capacities differed depending on maternal temperature and offspring of warm acclimated mothers that were reared at warm temperatures showed full metabolic compensation with respect to heart mitochondrial capacities in comparison to the control groups. Our results for mitochondrial capacities between the different offspring groups suggest that mitochondria are a primary target for non-genetic transgenerational thermal compensation of metabolic rates in a changing climate, as an optimized energy metabolism will generate a higher scope for growth. Warm acclimated mothers adjust the metabolism of mitochondria that are inherited by offspring, and differences in mitochondrial capacities and efficiency underlie the differences observed in offspring growth.