Astrid Wittmann - Academia.edu (original) (raw)
Papers by Astrid Wittmann
Alfred Wegener Institute Helmholtz Center For Polar and Marine Research Bremerhaven, Sep 19, 2012
Epic3fachbereich 2 Biologie Chemie Der Universitat Bremen 171 P, 2010
ABSTRACT It has been hypothesized that a low capacity for extracellular ion (magnesium) regulatio... more ABSTRACT It has been hypothesized that a low capacity for extracellular ion (magnesium) regulation in marine crustaceans constrains their cold tolerance and biogeography in the Southern Ocean. This thesis investigates whether there is a relationship between haemolymph magnesium concentration and thermal tolerance in a temperate brachyuran crab (Carcinus maenas, Decapoda, Brachyura, Carcinidae) and in decapod, amphipod and isopod crustaceans from the Southern Ocean. In the sub-Antarctic stone crab Paralomis granulosa (Decapoda, Anomura, Lithodidae) lecithotrophic larvae, juvenile and adult stages were considered. Haemolymph ion composition, cardiovascular variables, locomotory activity, and developmental time were determined. As observed in isopods, life in the extremely cold continental shelf areas of the Antarctic is generally possible despite high haemolymph magnesium concentrations. The findings in P. granulosa render it unlikely that high haemolymph magnesium concentrations are correlated with the absence of this species from extremely cold regions of the Antarctic.
Epic3annual Main Meeting of the Society For Experimental Biology 31 March 4 April 2007 Glasgow Great Britain, 2007
Epic342nd European Marine Biology Symposium Kiel Germany 31 August 2007 27, 2007
ABSTRACT It has been hypothesized that a low capacity for extracellular ion (magnesium) regulatio... more ABSTRACT It has been hypothesized that a low capacity for extracellular ion (magnesium) regulation in marine crustaceans constrains their cold tolerance and biogeography in the Southern Ocean. This thesis investigates whether there is a relationship between haemolymph magnesium concentration and thermal tolerance in a temperate brachyuran crab (Carcinus maenas, Decapoda, Brachyura, Carcinidae) and in decapod, amphipod and isopod crustaceans from the Southern Ocean. In the sub-Antarctic stone crab Paralomis granulosa (Decapoda, Anomura, Lithodidae) lecithotrophic larvae, juvenile and adult stages were considered. Haemolymph ion composition, cardiovascular variables, locomotory activity, and developmental time were determined. As observed in isopods, life in the extremely cold continental shelf areas of the Antarctic is generally possible despite high haemolymph magnesium concentrations. The findings in P. granulosa render it unlikely that high haemolymph magnesium concentrations are correlated with the absence of this species from extremely cold regions of the Antarctic.
Epic3epamocgec Workshop Marine Organisms and Problems of Global Climate Changes 19 25 April St Petersburg Russia, 2006
Epic3esf Thermadapt Workshop the Effects of Climate Change on Vulnerable Life Traits of Aquatic Ectotherms Towards an Integrated Approach Bremerhaven Germany 2011 09 18 2011 09 21, 2011
Epic3annual Main Meeting of the Society For Experimental Biology June 29 July 3 Prague Czech Republic, 2010
Epic314 Crustaceologentagung 2 5 April 2009 Rostock, 2009
Epic3diplomarbeit Im Fach Biologie Fachbereich Ii, 2005
Epic3society For Experimental Biology Annual Main Meeting Salzburg Austria 2012 06 28 2012 07 02, Jun 30, 2012
We hypothesize that the mTOR pathway and AMP-dependent protein kinase (AMPK) are involved in the ... more We hypothesize that the mTOR pathway and AMP-dependent protein kinase (AMPK) are involved in the regulation of the molt cycle in response to temperature in juvenile Dungeness crabs Metacarcinus magister. We used PCR cloning to obtain partial cDNA sequences of mTOR, Rheb, AKT, S6K and AMPK. We incubated crabs at 12 d, 18 d and 26 d postmolt at 5, 10, 15, 20, 25 and 30°C for up to 14 d to study survival and progression of the molt cycle. We determined gene expression in the molting gland of AMPK, AKT and Rheb (upstream of mTOR), mTOR, S6K (downstream of mTOR) and of the possible reference gene RbS3 by quantitative real-time PCR in crabs that had been held at 10, 15 or 20°C. Hemolymph molting hormone titers were determined by ecdysteroid ELISA. Survival was 97-100% at temperatures from 5-20°C, and was time-dependent, but 0% after 14 d at 25°C. All animals had died after 24 h at 30°C. Progression of the molt cycle was observed at 10, 15 and 20°C, but not at 5°C. Two-way ANOVA revealed a...
... measures of climate dependent organismal performance investigated in populations of the lugwo... more ... measures of climate dependent organismal performance investigated in populations of the lugworm Arenicola marina in a latitudinal cline, Proceedings of ... oxygen affinity on the supply side in populations of Arenicola marina from the French Atlantic coast, the German North Sea ...
Physiological and Biochemical Zoology, 2012
A low capacity for regulation of extracellular Mg(2+) has been proposed to exclude reptant marine... more A low capacity for regulation of extracellular Mg(2+) has been proposed to exclude reptant marine decapod crustaceans from temperatures below 0°C and thus to exclude them from the high Antarctic. To test this hypothesis and to elaborate the underlying mechanisms in the most cold-tolerant reptant decapod family of the sub-Antarctic, the Lithodidae, thermal tolerance was determined in the crab Paralomis granulosa (Decapoda, Anomura, Lithodidae) using an acute stepwise temperature protocol (-1°, 1°, 4°, 7°, 10°, and 13°C). Arterial and venous oxygen partial pressures (Po(2)) in hemolymph, heartbeat and ventilation beat frequencies, and hemolymph cation composition were measured at rest and after a forced activity (righting) trial. Scopes for heartbeat and ventilation beat frequencies and intermittent heartbeat and scaphognathite beat rates at rest were evaluated. Hemolymph [Mg(2+)] was experimentally reduced from 30 mmol L(-1) to a level naturally observed in Antarctic caridean shrimps (12 mmol L(-1)) to investigate whether the animals remain more active and tolerant to cold (-1°, 1°, and 4°C). In natural seawater, righting speed was significantly slower at -1° and 13°C, compared with acclimation temperature (4°C). Arterial and venous hemolymph Po(2) increased in response to cooling even though heartbeat and ventilation beat frequencies as well as scopes decreased. At rest, ionic composition of the hemolymph was not affected by temperature. Activity induced a significant increase in hemolymph [K(+)] at -1° and 1°C. Reduction of hemolymph [Mg(2+)] did not result in an increase in activity, an increase in heartbeat and ventilation beat frequencies, or a shift in thermal tolerance to lower temperatures. In conclusion, oxygen delivery in this cold-water crustacean was not acutely limiting cold tolerance, and animals may have been constrained more by their functional capacity and motility. In contrast to earlier findings in temperate and subpolar brachyuran crabs, these constraints remained insensitive to changing Mg(2+) levels.
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2007
ABSTRACT It has been hypothesized that a low capacity for extracellular ion (magnesium) regulatio... more ABSTRACT It has been hypothesized that a low capacity for extracellular ion (magnesium) regulation in marine crustaceans constrains their cold tolerance and biogeography in the Southern Ocean. This thesis investigates whether there is a relationship between haemolymph magnesium concentration and thermal tolerance in a temperate brachyuran crab (Carcinus maenas, Decapoda, Brachyura, Carcinidae) and in decapod, amphipod and isopod crustaceans from the Southern Ocean. In the sub-Antarctic stone crab Paralomis granulosa (Decapoda, Anomura, Lithodidae) lecithotrophic larvae, juvenile and adult stages were considered. Haemolymph ion composition, cardiovascular variables, locomotory activity, and developmental time were determined. As observed in isopods, life in the extremely cold continental shelf areas of the Antarctic is generally possible despite high haemolymph magnesium concentrations. The findings in P. granulosa render it unlikely that high haemolymph magnesium concentrations are correlated with the absence of this species from extremely cold regions of the Antarctic.
Polar Biology, 2009
... Tucker 1990) with observed salinity minima of SR < 2 g/kg (Werner and Martinez Arbizu ... more ... Tucker 1990) with observed salinity minima of SR < 2 g/kg (Werner and Martinez Arbizu 1999). ... R. Kiko · A. Wittmann Alfred-Wegener-Institute for Polar and Marine Research, Am Handelshafen 12 ... They were reared in filtered seawater (T = 0°C, SR =2734g/kg) and supplied with ...
Polar Biology
Amphipods living at the underside of Arctic sea ice are exposed to varying salinities due to free... more Amphipods living at the underside of Arctic sea ice are exposed to varying salinities due to freezing and melting, and have to cope with the resulting osmotic stress. Extracellular osmotic and ionic regulation at different salinities, thermal hysteresis, and supercooling points (SCPs) were studied in the under-ice amphipod Apherusa glacialis. The species is euryhaline, capable to regulate hyperosmotically at salinities S R<30g/kg, and osmoconforms at salinities S R≥30g/kg. Hyperosmotic regulation is an adaptation to thrive in low-salinity meltwater below the ice. Conforming to the ambient salinity during freezing reduces the risk of internal ice formation. Thermal hysteresis was not observed in the haemolymph of A. glacialis. The SCP of the species was −7.8±1.9°C. Several ions were specifically downregulated ([Mg2+], [SO4 2−]), or upregulated ([K+], [Ca2+]) in comparison to the medium. Strong downregulation of [Mg2+], is probably necessary to avoid an anaesthetic effect at low te...
Nature Climate Change, 2013
ABSTRACT Anthropogenic CO2 emitted to the atmosphere is absorbed by the oceans, causing a progres... more ABSTRACT Anthropogenic CO2 emitted to the atmosphere is absorbed by the oceans, causing a progressive increase in ocean inorganic carbon concentrations and resulting in decreased water pH and calcium carbonate saturation. This phenomenon, called ocean acidification, is in addition to the warming effects of CO2 emissions. Ocean acidification has been reported to affect ocean biota, but the severity of this threat to ocean ecosystems (and humans depending on these ecosystems) is poorly understood. Here we evaluate the scale of this threat in the context of widely used representative concentration pathways (RCPs) by analysing the sensitivities of five animal taxa (corals, echinoderms, molluscs, crustaceans and fishes) to a wide range of CO2 concentrations. Corals, echinoderms and molluscs are more sensitive to RCP8.5 (936 ppm in 2100) than are crustaceans. Larval fishes may be even more sensitive than the lower invertebrates, but taxon sensitivity on evolutionary timescales remains obscure. The variety of responses within and between taxa, together with observations in mesocosms and palaeo-analogues, suggest that ocean acidification is a driver for substantial change in ocean ecosystems this century, potentially leading to long-term shifts in species composition.
Alfred Wegener Institute Helmholtz Center For Polar and Marine Research Bremerhaven, Sep 19, 2012
Epic3fachbereich 2 Biologie Chemie Der Universitat Bremen 171 P, 2010
ABSTRACT It has been hypothesized that a low capacity for extracellular ion (magnesium) regulatio... more ABSTRACT It has been hypothesized that a low capacity for extracellular ion (magnesium) regulation in marine crustaceans constrains their cold tolerance and biogeography in the Southern Ocean. This thesis investigates whether there is a relationship between haemolymph magnesium concentration and thermal tolerance in a temperate brachyuran crab (Carcinus maenas, Decapoda, Brachyura, Carcinidae) and in decapod, amphipod and isopod crustaceans from the Southern Ocean. In the sub-Antarctic stone crab Paralomis granulosa (Decapoda, Anomura, Lithodidae) lecithotrophic larvae, juvenile and adult stages were considered. Haemolymph ion composition, cardiovascular variables, locomotory activity, and developmental time were determined. As observed in isopods, life in the extremely cold continental shelf areas of the Antarctic is generally possible despite high haemolymph magnesium concentrations. The findings in P. granulosa render it unlikely that high haemolymph magnesium concentrations are correlated with the absence of this species from extremely cold regions of the Antarctic.
Epic3annual Main Meeting of the Society For Experimental Biology 31 March 4 April 2007 Glasgow Great Britain, 2007
Epic342nd European Marine Biology Symposium Kiel Germany 31 August 2007 27, 2007
ABSTRACT It has been hypothesized that a low capacity for extracellular ion (magnesium) regulatio... more ABSTRACT It has been hypothesized that a low capacity for extracellular ion (magnesium) regulation in marine crustaceans constrains their cold tolerance and biogeography in the Southern Ocean. This thesis investigates whether there is a relationship between haemolymph magnesium concentration and thermal tolerance in a temperate brachyuran crab (Carcinus maenas, Decapoda, Brachyura, Carcinidae) and in decapod, amphipod and isopod crustaceans from the Southern Ocean. In the sub-Antarctic stone crab Paralomis granulosa (Decapoda, Anomura, Lithodidae) lecithotrophic larvae, juvenile and adult stages were considered. Haemolymph ion composition, cardiovascular variables, locomotory activity, and developmental time were determined. As observed in isopods, life in the extremely cold continental shelf areas of the Antarctic is generally possible despite high haemolymph magnesium concentrations. The findings in P. granulosa render it unlikely that high haemolymph magnesium concentrations are correlated with the absence of this species from extremely cold regions of the Antarctic.
Epic3epamocgec Workshop Marine Organisms and Problems of Global Climate Changes 19 25 April St Petersburg Russia, 2006
Epic3esf Thermadapt Workshop the Effects of Climate Change on Vulnerable Life Traits of Aquatic Ectotherms Towards an Integrated Approach Bremerhaven Germany 2011 09 18 2011 09 21, 2011
Epic3annual Main Meeting of the Society For Experimental Biology June 29 July 3 Prague Czech Republic, 2010
Epic314 Crustaceologentagung 2 5 April 2009 Rostock, 2009
Epic3diplomarbeit Im Fach Biologie Fachbereich Ii, 2005
Epic3society For Experimental Biology Annual Main Meeting Salzburg Austria 2012 06 28 2012 07 02, Jun 30, 2012
We hypothesize that the mTOR pathway and AMP-dependent protein kinase (AMPK) are involved in the ... more We hypothesize that the mTOR pathway and AMP-dependent protein kinase (AMPK) are involved in the regulation of the molt cycle in response to temperature in juvenile Dungeness crabs Metacarcinus magister. We used PCR cloning to obtain partial cDNA sequences of mTOR, Rheb, AKT, S6K and AMPK. We incubated crabs at 12 d, 18 d and 26 d postmolt at 5, 10, 15, 20, 25 and 30°C for up to 14 d to study survival and progression of the molt cycle. We determined gene expression in the molting gland of AMPK, AKT and Rheb (upstream of mTOR), mTOR, S6K (downstream of mTOR) and of the possible reference gene RbS3 by quantitative real-time PCR in crabs that had been held at 10, 15 or 20°C. Hemolymph molting hormone titers were determined by ecdysteroid ELISA. Survival was 97-100% at temperatures from 5-20°C, and was time-dependent, but 0% after 14 d at 25°C. All animals had died after 24 h at 30°C. Progression of the molt cycle was observed at 10, 15 and 20°C, but not at 5°C. Two-way ANOVA revealed a...
... measures of climate dependent organismal performance investigated in populations of the lugwo... more ... measures of climate dependent organismal performance investigated in populations of the lugworm Arenicola marina in a latitudinal cline, Proceedings of ... oxygen affinity on the supply side in populations of Arenicola marina from the French Atlantic coast, the German North Sea ...
Physiological and Biochemical Zoology, 2012
A low capacity for regulation of extracellular Mg(2+) has been proposed to exclude reptant marine... more A low capacity for regulation of extracellular Mg(2+) has been proposed to exclude reptant marine decapod crustaceans from temperatures below 0°C and thus to exclude them from the high Antarctic. To test this hypothesis and to elaborate the underlying mechanisms in the most cold-tolerant reptant decapod family of the sub-Antarctic, the Lithodidae, thermal tolerance was determined in the crab Paralomis granulosa (Decapoda, Anomura, Lithodidae) using an acute stepwise temperature protocol (-1°, 1°, 4°, 7°, 10°, and 13°C). Arterial and venous oxygen partial pressures (Po(2)) in hemolymph, heartbeat and ventilation beat frequencies, and hemolymph cation composition were measured at rest and after a forced activity (righting) trial. Scopes for heartbeat and ventilation beat frequencies and intermittent heartbeat and scaphognathite beat rates at rest were evaluated. Hemolymph [Mg(2+)] was experimentally reduced from 30 mmol L(-1) to a level naturally observed in Antarctic caridean shrimps (12 mmol L(-1)) to investigate whether the animals remain more active and tolerant to cold (-1°, 1°, and 4°C). In natural seawater, righting speed was significantly slower at -1° and 13°C, compared with acclimation temperature (4°C). Arterial and venous hemolymph Po(2) increased in response to cooling even though heartbeat and ventilation beat frequencies as well as scopes decreased. At rest, ionic composition of the hemolymph was not affected by temperature. Activity induced a significant increase in hemolymph [K(+)] at -1° and 1°C. Reduction of hemolymph [Mg(2+)] did not result in an increase in activity, an increase in heartbeat and ventilation beat frequencies, or a shift in thermal tolerance to lower temperatures. In conclusion, oxygen delivery in this cold-water crustacean was not acutely limiting cold tolerance, and animals may have been constrained more by their functional capacity and motility. In contrast to earlier findings in temperate and subpolar brachyuran crabs, these constraints remained insensitive to changing Mg(2+) levels.
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2007
ABSTRACT It has been hypothesized that a low capacity for extracellular ion (magnesium) regulatio... more ABSTRACT It has been hypothesized that a low capacity for extracellular ion (magnesium) regulation in marine crustaceans constrains their cold tolerance and biogeography in the Southern Ocean. This thesis investigates whether there is a relationship between haemolymph magnesium concentration and thermal tolerance in a temperate brachyuran crab (Carcinus maenas, Decapoda, Brachyura, Carcinidae) and in decapod, amphipod and isopod crustaceans from the Southern Ocean. In the sub-Antarctic stone crab Paralomis granulosa (Decapoda, Anomura, Lithodidae) lecithotrophic larvae, juvenile and adult stages were considered. Haemolymph ion composition, cardiovascular variables, locomotory activity, and developmental time were determined. As observed in isopods, life in the extremely cold continental shelf areas of the Antarctic is generally possible despite high haemolymph magnesium concentrations. The findings in P. granulosa render it unlikely that high haemolymph magnesium concentrations are correlated with the absence of this species from extremely cold regions of the Antarctic.
Polar Biology, 2009
... Tucker 1990) with observed salinity minima of SR < 2 g/kg (Werner and Martinez Arbizu ... more ... Tucker 1990) with observed salinity minima of SR < 2 g/kg (Werner and Martinez Arbizu 1999). ... R. Kiko · A. Wittmann Alfred-Wegener-Institute for Polar and Marine Research, Am Handelshafen 12 ... They were reared in filtered seawater (T = 0°C, SR =2734g/kg) and supplied with ...
Polar Biology
Amphipods living at the underside of Arctic sea ice are exposed to varying salinities due to free... more Amphipods living at the underside of Arctic sea ice are exposed to varying salinities due to freezing and melting, and have to cope with the resulting osmotic stress. Extracellular osmotic and ionic regulation at different salinities, thermal hysteresis, and supercooling points (SCPs) were studied in the under-ice amphipod Apherusa glacialis. The species is euryhaline, capable to regulate hyperosmotically at salinities S R<30g/kg, and osmoconforms at salinities S R≥30g/kg. Hyperosmotic regulation is an adaptation to thrive in low-salinity meltwater below the ice. Conforming to the ambient salinity during freezing reduces the risk of internal ice formation. Thermal hysteresis was not observed in the haemolymph of A. glacialis. The SCP of the species was −7.8±1.9°C. Several ions were specifically downregulated ([Mg2+], [SO4 2−]), or upregulated ([K+], [Ca2+]) in comparison to the medium. Strong downregulation of [Mg2+], is probably necessary to avoid an anaesthetic effect at low te...
Nature Climate Change, 2013
ABSTRACT Anthropogenic CO2 emitted to the atmosphere is absorbed by the oceans, causing a progres... more ABSTRACT Anthropogenic CO2 emitted to the atmosphere is absorbed by the oceans, causing a progressive increase in ocean inorganic carbon concentrations and resulting in decreased water pH and calcium carbonate saturation. This phenomenon, called ocean acidification, is in addition to the warming effects of CO2 emissions. Ocean acidification has been reported to affect ocean biota, but the severity of this threat to ocean ecosystems (and humans depending on these ecosystems) is poorly understood. Here we evaluate the scale of this threat in the context of widely used representative concentration pathways (RCPs) by analysing the sensitivities of five animal taxa (corals, echinoderms, molluscs, crustaceans and fishes) to a wide range of CO2 concentrations. Corals, echinoderms and molluscs are more sensitive to RCP8.5 (936 ppm in 2100) than are crustaceans. Larval fishes may be even more sensitive than the lower invertebrates, but taxon sensitivity on evolutionary timescales remains obscure. The variety of responses within and between taxa, together with observations in mesocosms and palaeo-analogues, suggest that ocean acidification is a driver for substantial change in ocean ecosystems this century, potentially leading to long-term shifts in species composition.