Papers by Hans-o. Pörtner
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2002
The physiological mechanisms limiting and adjusting cold and heat tolerance have regained interes... more The physiological mechanisms limiting and adjusting cold and heat tolerance have regained interest in the light of global warming and associated shifts in the geographical distribution of ectothermic animals. Recent comparative studies, largely carried out on marine ectotherms, indicate that the processes and limits of thermal tolerance are linked with the adjustment of aerobic scope and capacity of the whole animal as a crucial step in thermal adaptation on top of parallel adjustments at the molecular or membrane level. In accordance with Shelford's law of tolerance decreasing whole animal aerobic scope characterises the onset of thermal limitation at low and high pejus thresholds (pejussgetting worse). The aerobic scope of an animal indicated by falling oxygen levels in the body fluids and or the progressively limited capacity of circulatory and ventilatory mechanisms. At high temperatures, excessive oxygen demand causes insufficient oxygen levels in the body fluids, whereas at low temperatures the aerobic capacity of mitochondria may become limiting for ventilation and circulation. Further cooling or warming beyond these limits leads to low or high critical threshold temperatures (T ) where aerobic scope disappears and transition to an anaerobic mode of mitochondrial metabolism and c progressive insufficiency of cellular energy levels occurs. The adjustments of mitochondrial densities and their functional properties appear as a critical process in defining and shifting thermal tolerance windows. The finding of an oxygen limited thermal tolerance owing to loss of aerobic scope is in line with Taylor's and Weibel's concept of symmorphosis, which implies that excess capacity of any component of the oxygen delivery system is avoided. The present study suggests that the capacity of oxygen delivery is set to a level just sufficient to meet maximum oxygen demand between the average highs and lows of environmental temperatures. At more extreme temperatures only time limited passive survival is supported by anaerobic metabolism or the protection of molecular functions by heat shock proteins and antioxidative defence. As a corollary, the first line of thermal sensitivity is due to capacity limitations at a high level of organisational complexity, i.e. the integrated function of the oxygen delivery system, before individual, molecular or membrane functions become disturbed. These interpretations are in line with the more general consideration that, as a result of the high level of complexity of metazoan organisms compared with simple eukaryotes and then prokaryotes, thermal tolerance is reduced in metazoans. A similar sequence of sensitivities prevails within the metazoan organism, with the highest sensitivity at the organismic level and wider tolerance windows at lower levels of complexity. However, the situation is different in that loss in aerobic scope and progressive hypoxia at the organismic level define the onset of thermal limitation which then transfers to lower hierarchical levels and causes cellular and molecular disturbances. Oxygen limitation contributes to oxidative stress and, finally, denaturation or malfunction of molecular repair, e.g. during suspension of protein synthesis. The sequence of thermal tolerance limits turns into a hierarchy, ranging from systemic to cellular to molecular levels.
Physiological and Biochemical Zoology, 2006
Through functional analyses, integrative physiology is able to link molecular biology with ecolog... more Through functional analyses, integrative physiology is able to link molecular biology with ecology as well as evolutionary biology and is thereby expected to provide access to the evolution of molecular, cellular, and organismic functions; the genetic basis of adaptability; and the shaping of ecological patterns. This paper compiles several exemplary studies of thermal physiology and ecology, carried out at various levels of biological organization from single genes (proteins) to ecosystems.
Marine Ecology Progress Series, 2012
The role of thermal stress phenomena in setting stratified distribution limits was investigated i... more The role of thermal stress phenomena in setting stratified distribution limits was investigated in the bearded horse mussel Modiolus barbatus in response to the seasonal temperature regime in the field. Mussels were transplanted from their natural depth range at ca. 20 m to 3 m depth, where they then experienced enhanced variability of ambient conditions. In specimens from both depths, thermal stress was assessed from the inducible heat shock response (HSR), the accumulation of irreversibly damaged proteins, and from metabolic characters including the putative shift from aerobic to anaerobic metabolism. During both winter and summer, the HSR became involved more at shallow depths than at 20 m depth. The accumulation of succinate during summer indicates transition to anaerobiosis. The results suggest that the development of anaerobic conditions and the exploitation of the HSR are closely intertwined. The field data corroborate that glycolytic capacity, the level of energy turnover, and also protection from protein damage play a role in setting passive tolerance to extremes in environmental temperature. We suggest that limits to vertical distribution of M. barbatus are set by the time and degree of exploitation of the mechanisms sustaining passive thermal tolerance and the avoidance of protein damage in the warmth.
Marine Ecology Progress Series, 2006
uncoupling to survive' hypothesis by attempts to explain this contradiction by proposing that mit... more uncoupling to survive' hypothesis by attempts to explain this contradiction by proposing that mitochondrial uncoupling modulates ROS production, thus altering the strict dependency of ROS formation on SMR. A recent comparison of sessile infaunal soft-shell clams from temperate regions (Mya arenaria) and from Antarctica (Laternula elliptica) (Philipp et al. 2005a,b), showed that lower metabolic rates of the Antarctic L. elliptica, along with the maintenance of a reduced tissue redox-state, lower mitochondrial H 2 O 2 generation, and a less pronounced decline in mitochondrial func-© Inter-Research 2006 • www.
…, 2009
Biogeosciences, 6, 23132331, 2009 www.biogeosciences.net/6/2313/2009/ © Author(s) 2009. This wor... more Biogeosciences, 6, 23132331, 2009 www.biogeosciences.net/6/2313/2009/ © Author(s) 2009. This work is distributed under the Creative Commons Attribution 3.0 License. ... Physiological basis for high CO2 tolerance in marine ectothermic ... F. Melzner1, MA Gutowska2, M. ...
Ecology and Evolution, 2015
In this article, we pointed out that understanding the physiology of differential climate change ... more In this article, we pointed out that understanding the physiology of differential climate change effects on organisms is one of the many urgent challenges faced in ecology and evolutionary biology. We explore how physiological ecology can contribute to a holistic view of climate change impacts on organisms and ecosystems and their evolutionary responses. We suggest that theoretical and experimental efforts not only need to improve our understanding of thermal limits to organisms, but also to consider multiple stressors both on land and in the oceans. As an example, we discuss recent efforts to understand the effects of various global change drivers on aquatic ectotherms in the field that led to the development of the concept of oxygen and capacity limited thermal tolerance (OCLTT) as a framework integrating various drivers and linking organisational levels from ecosystem to organism, tissue, cell, and molecules. We suggest seven core objectives of a comprehensive research program comprising the interplay among physiological, ecological, and evolutionary approaches for both aquatic and terrestrial organisms. While studies of individual aspects are already underway in many laboratories worldwide, integration of these findings into conceptual frameworks is needed not only within one organism group such as animals but also across organism domains such as Archaea, Bacteria, and Eukarya. Indeed, development of unifying concepts is relevant for interpreting existing and future findings in a coherent way and for projecting the future ecological and evolutionary effects of climate change on functional biodiversity. We also suggest that OCLTT may in the end and from an evolutionary point of view, be able to explain the limited thermal tolerance of metazoans when compared to other organisms.
Journal of Experimental Marine Biology and Ecology, 2011
Marine brachyuran and anomuran crustaceans are completely absent from the extremely cold (−1.8°C)... more Marine brachyuran and anomuran crustaceans are completely absent from the extremely cold (−1.8°C) Antarctic continental shelf, but caridean shrimps are abundant. This has at least partly been attributed to low capacities for magnesium excretion in brachyuran and anomuran lithodid crabs ([Mg 2+ ] HL =20-50 mmol L − 1 ) compared to caridean shrimp species ([Mg 2+ ] HL =5-12 mmol L − 1 ). Magnesium has an anaesthetizing effect and reduces cold tolerance and activity of adult brachyuran crabs. We investigated whether the capacity for magnesium regulation is a factor that influences temperature-dependent activity of early ontogenetic stages of the Sub-Antarctic lithodid crab Paralomis granulosa. Ion composition (Na + , Mg 2+ , Ca 2+ , Cl − , SO 4 2− ) was measured in haemolymph withdrawn from larval stages, the first and second juvenile instars (crabs I and II) and adult males and females. Magnesium excretion improved during ontogeny, but haemolymph sulphate concentration was lowest in the zoeal stages. Neither haemolymph magnesium concentrations nor Ca 2+ :Mg 2+ ratios paralleled activity levels of the life stages. Long-term (3 week) cold exposure of crab I to 1°C caused a significant rise of haemolymph sulphate concentration and a decrease in magnesium and calcium concentrations compared to control temperature (9°C). Spontaneous swimming activity of the zoeal stages was determined at 1, 4 and 9°C in natural sea water (NSW, [Mg 2+ ] = 51 mmol L − 1 ) and in sea water enriched with magnesium (NSW+ Mg 2+ , [Mg 2+ ] = 97 mmol L − 1 ). It declined significantly with temperature but only insignificantly with increased magnesium concentration. Spontaneous velocities were low, reflecting the demersal life style of the zoeae. Heart rate, scaphognathite beat rate and forced swimming activity (maxilliped beat rate, zoea I) or antennule beat rate (crab I) were investigated in response to acute temperature change (9, 6, 3, 1, −1°C) in NSW or NSW+ Mg 2+ . High magnesium concentration reduced heart rates in both stages. The temperature-frequency curve of the maxilliped beat (maximum: 9.6 beats s − 1 at 6.6°C in NSW) of zoea I was depressed and shifted towards warmer temperatures by 2°C in NSW+ Mg 2+ , but antennule beat rate of crab I was not affected. Magnesium may therefore influence cold tolerance of highly active larvae, but it remains questionable whether the slow-moving lithodid crabs with demersal larvae would benefit from an enhanced magnesium excretion in nature.
Polar Biology, 2010
Brachyuran and anomuran decapod crabs do not occur in the extremely cold waters of the Antarctic ... more Brachyuran and anomuran decapod crabs do not occur in the extremely cold waters of the Antarctic continental shelf whereas caridean and other shrimp-like decapods, amphipods and isopods are highly abundant. DiVering capacities for extracellular ion regulation, especially concerning magnesium, have been hypothesised to determine cold tolerance and by that the biogeography of Antarctic crustaceans. Magnesium is known to have a paralysing eVect, which is even more distinct in the cold. As only few or no data exist on haemolymph ionic composition of Sub-Antarctic and Antarctic crustaceans, haemolymph samples of 12 species from these regions were analysed for the concentrations of major inorganic ions (Na + , K + , Ca 2+ , Mg 2+ , Cl ¡ , SO 4 2¡ ) by ion chromatography. Cation relationships guaranteed neuromuscular excitability in all species. Sulphate and potassium correlated positively with magnesium concentration. The Antarctic caridean decapod as well as the amphipods maintained low (6-20% of ambient sea water magnesium concentration), Sub-Antarctic brachyuran and anomuran crabs as well as the Antarctic isopods high (54-96% of ambient sea water magnesium concentration) haemolymph magnesium levels. In conclusion, magnesium regulation may explain the biogeography of decapods, but not that of the peracarids.
Implications of the Paris agreement for the ocean
Nature Climate Change, 2016
ESF Science Policy Briefing, 2009
There is growing scientific evidence that, as a result of increasing anthropogenic carbon dioxide... more There is growing scientific evidence that, as a result of increasing anthropogenic carbon dioxide (CO2) emissions, absorption of CO2 by the oceans has already noticeably increased the average oceanic acidity from pre-industrial levels. This global threat requires a global response. According to the Intergovernmental Panel on Climate Change (IPCC), continuing CO2 emissions in line with current trends could make the oceans up to 150% more acidic by 2100 than they were at the beginning of the Anthropocene. Acidification ...
Physiological and …, 2006
Through functional analyses, integrative physiology is able to link molecular biology with ecolog... more Through functional analyses, integrative physiology is able to link molecular biology with ecology as well as evolutionary biology and is thereby expected to provide access to the evolution of molecular, cellular, and organismic functions; the genetic basis of adaptability; and the shaping of ecological patterns. This paper compiles several exemplary studies of thermal physiology and ecology, carried out at various levels of biological organization from single genes (proteins) to ecosystems. * This paper was prepared as an overview of a symposium session presented at "
Hyperoxia alleviates thermal stress in the Antarctic bivalve, Laternula elliptica: evidence for oxygen limited thermal tolerance
Polar Biology, 2006
... initial aerobic limitation and critical temperatures, oxy-gen restrictions may already enhanc... more ... initial aerobic limitation and critical temperatures, oxy-gen restrictions may already enhanceoxidative stress (Heise et ... Point (67°34ĒS, 68°08ĒW) in January 2000 were held in runningseawater (Ā0.6 ... PO2 =300 mmHg at 0°C and 298 mmHg at 10°C) sea-water conditions were ...
Marine Biology, 2009
The upper thermal limits for burrowing and survival were compared with micro-habitat temperature ... more The upper thermal limits for burrowing and survival were compared with micro-habitat temperature for anomalodesmatan clams: Laternula elliptica (Antarctica, 67°S); Laternula recta, (temperate Australia, 38°S) and Laternula truncata (tropical Singapore, 1°N). Lethal limits (LT 50 ) were higher than burrowing limits (BT 50 ) in L. elliptica (7.5-9.0 and 2.2°C) and L. recta (winter, 32.8-36.8 and 31.1-32.8°C) but the same range for L. truncata (33.0-35.0 and 33.4-34.9°C). L. elliptica and L. truncata had a BT 50 0.4 and 2.4-3.9°C, respectively, above their maximum experienced temperature. L. recta, which experience solar heating during midday low tides, had a BT 50 0.7-2.4°C below and a range for LT 50 that spanned their predicted environmental maximum (33.5°C). L. recta showed no seasonal difference in LT 50 or BT 50 . Our single genus comparisons contrast with macrophysiological studies showing that temperate species cope better with elevated temperatures. Communicated by J. P. Grassle.
The mechanism of an increase in metabolic rate induced by lactate was investigated in the toad Bu... more The mechanism of an increase in metabolic rate induced by lactate was investigated in the toad Bufo marinus. Oxygen consumption was analyzed in fully aerobic animals under hypoxic conditions (7%O 2 in air), accompanied by measurements of catecholamines in the plasma, and in isolated hepatocytes in vitro, under normoxia, using specific inhibitors of lactate proton symport (α-CHC = α-cyano-4hydroxycinnamate) and sodium proton exchange (EIPA = 5-(Ethyl-N-Isopropyl)amiloride). The rise in metabolic rate in vivo can be elicited by infusions of hyperosmotic (previous findings) or isosmotic sodium lactate solutions (this study).
Ecosystem impacts of climate change and ocean acidification: A case for “global” conservation physiology
The upper thermal limits for burrowing and survival were compared with micro-habitat temperature ... more The upper thermal limits for burrowing and survival were compared with micro-habitat temperature for anomalodesmatan clams: Laternula elliptica (Antarctica, 67°S); Laternula recta, (temperate Australia, 38°S) and Laternula truncata (tropical Singapore, 1°N). Lethal limits (LT 50 ) were higher than burrowing limits (BT 50 ) in L. elliptica (7.5-9.0 and 2.2°C) and L. recta (winter, 32.8-36.8 and 31.1-32.8°C) but the same range for L. truncata (33.0-35.0 and 33.4-34.9°C). L. elliptica and L. truncata had a BT 50 0.4 and 2.4-3.9°C, respectively, above their maximum experienced temperature. L. recta, which experience solar heating during midday low tides, had a BT 50 0.7-2.4°C below and a range for LT 50 that spanned their predicted environmental maximum (33.5°C). L. recta showed no seasonal difference in LT 50 or BT 50 . Our single genus comparisons contrast with macrophysiological studies showing that temperate species cope better with elevated temperatures. Communicated by J. P. Grassle.
Comparative Biochemistry and Physiology B-biochemistry & Molecular Biology, 2000
Activities of the antioxidative enzymes superoxide dismutase (SOD), catalase, glutathione peroxid... more Activities of the antioxidative enzymes superoxide dismutase (SOD), catalase, glutathione peroxidase (GPX) and glutathione reductase (GR) were measured in the cephalopods Sepia officinalis and Lolliguncula brevis. Maximal enzyme activities were higher in gill tissue than in the mantle musculature of both species. Activities were generally lower in tissues of L. brevis than in S. officinalis. Comparison with other ectothermic animals
Journal of Experimental Marine Biology and Ecology, 2009
Global warming trends in the marine environment currently lead to poleward shifts in the distribu... more Global warming trends in the marine environment currently lead to poleward shifts in the distribution of marine fauna along European coastlines indicating limited thermal tolerance of affected species and potential loss of their southernmost populations. The present study analyses the degree and limits of thermal specialisation in various populations of a key species of the intertidal zone, the lugworm Arenicola
The American Naturalist, 2009
Widespread recognition of the importance of biological studies at large spatial and temporal scal... more Widespread recognition of the importance of biological studies at large spatial and temporal scales, particularly in the face of many of the most pressing issues facing humanity, has fueled the argument that there is a need to reinvigorate such studies in physiological ecology through the establishment of a macrophysiology. Following a period when the fields of ecology and physiological ecology had been regarded as largely synonymous, studies of this kind were relatively commonplace in the first half of the twentieth century. However, such large-scale work subsequently became rather scarce as physiological studies concentrated on the biochemical and molecular mechanisms underlying the capacities and tolerances of species. In some sense, macrophysiology is thus an attempt at a conceptual reunification. In this article, we provide a conceptual framework for the continued development of macrophysiology. We subdivide this framework into three major components: the establishment of macrophysiological patterns, determining the form of those patterns (the very general ways in which they are shaped), and understanding the mechanisms that give rise to them. We suggest ways in which each of these components could be developed usefully.
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Papers by Hans-o. Pörtner