Resistance to freshwater exposure in White Sea Littorina spp. II: Acid-base regulation

Sokolova, Inna M.; Bock, Christian; Pörtner, Hans‐Otto

doi:10.1007/s003600050265

Cited by 31 publications

(10 citation statements)

References 30 publications

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“…This agrees with the earlier findings that molluscan cells maintain the relatively stable pHi in a broad ranges of physiologically relevant pHe with ΔpHi of ~0.16-0.20 units over ΔpHe of 1.0-2.4 units (Zange et al, 1990;Ivanina et al, 2013)Heming, 1990 #11182}. The observed stability of pHi in hemocytes of oysters and clams under different CO2 conditions likely reflects the capacity for intracellular pH regulation including a variety of ion transporters (Ahearn et al, 2004) and intracellular buffers such as imidazole, phosphate and CaCO3 granules (Eberlee and Storey, 1984;Wiseman and Ellington, 1989;Sokolova et al, 2000;Mount et al, 2004). Notably, Cd exposure was the only effector that led to a significant perturbation of the hemocyte acid-base status shown by alkalinization of the intracellular milieu.…”

Section: Discussionmentioning

confidence: 92%

Effects of environmental hypercapnia and metal (Cd and Cu) exposure on acid-base and metal homeostasis of marine bivalves

Ivanina

Hawkins

Beniash

et al. 2015

Comparative Biochemistry and Physiology Part C: Toxicology &

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Elevated CO2 levels reduce seawater pH and may affect bioavailability of trace metals in estuaries. We studied the interactive effects of common metal pollutants (50 μg l(-1) Cd or Cu) and PCO2 (~395, 800 and 2000 μatm) on metal levels, intracellular pH, expression of metal binding proteins and stress biomarkers in estuarine bivalves Crassostrea virginica (oysters) and Mercenaria mercenaria (hard clams). Cd (but not Cu or hypercapnia) exposure affected the acid-base balance of hemocytes resulting in elevated intracellular pH. Cd and Cu exposure led to the increase in the tissue metal burdens, and metal accumulation was reduced by elevated PCO2 in the mantle but not hemocytes. No change was found in the intracellular free Cd(2+), Cu(2+) or Fe(2+) during Cu or Cd exposure indicating that these metals are bound to intracellular ligands. Free Zn(2+) content in oyster hemocytes was suppressed by Cd and Cu exposure and below the detection limits in clam hemocytes, which went hand-in-hand with the elevated mRNA expression of metallothioneins and ferritin in Cd- and Cu-exposed bivalves, enhanced by hypercapnia. The metal-binding and antioxidant mechanisms of oysters and clams were sufficient to effectively maintain intracellular redox status, even though metal exposure combined with moderate hypercapnia (~800 μatm PCO2) led to the elevated production of reactive oxygen species in hemocytes. Overall, while hypercapnia modulates metal accumulation, binding capacity and oxidative stress in estuarine bivalves, the physiological effects of elevated CO2 are mild compared to the effects of other common stressors.

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Section: Discussionmentioning

confidence: 92%

Effects of environmental hypercapnia and metal (Cd and Cu) exposure on acid-base and metal homeostasis of marine bivalves

Ivanina

Hawkins

Beniash

et al. 2015

Comparative Biochemistry and Physiology Part C: Toxicology &

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“…These observations indicate that etching of the shells' interior is not directly related to the water chemistry. One possible explanation is that the mollusks dissolve the interior of the shells to compensate for the effects of CO 2 -induced acidosis in the tissues as described in mollusks (Crenshaw, 1972;Sokolova et al, 2000). SEM analysis of the shells has also revealed that at low Ω Arg values, a significant erosion of the material in the hinge area occurred, leading to weakening of the ligament insertion site and separation of the shell valves.…”

Section: Discussionmentioning

confidence: 99%

Environmental salinity modulates the effects of elevated CO2 levels on juvenile hard shell clams, Mercenaria mercenaria

Dickinson

Matoo

Tourek

et al. 2013

Journal of Experimental Biology

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SUMMARYOcean acidification due to increasing atmospheric CO 2 concentrations results in a decrease in seawater pH and shifts in the carbonate chemistry that can negatively affect marine organisms. Marine bivalves such as the hard-shell clam, Mercenaria mercenaria, serve as ecosystem engineers in estuaries and coastal zones of the western Atlantic and, as for many marine calcifiers, are sensitive to the impacts of ocean acidification. In estuaries, the effects of ocean acidification can be exacerbated by low buffering capacity of brackish waters, acidic inputs from freshwaters and land, and/or the negative effects of salinity on the physiology of organisms. We determined the interactive effects of 21weeks of exposure to different levels of CO 2 (~395, 800 and 1500μatm corresponding to pH of 8.2, 8.1 and 7.7, respectively) and salinity (32 versus 16) on biomineralization, shell properties and energy metabolism of juvenile hard-shell clams. Low salinity had profound effects on survival, energy metabolism and biomineralization of hard-shell clams and modulated their responses to elevated P CO2 . Negative effects of low salinity in juvenile clams were mostly due to the strongly elevated basal energy demand, indicating energy deficiency, that led to reduced growth, elevated mortality and impaired shell maintenance (evidenced by the extensive damage to the periostracum). The effects of elevated P CO2 on physiology and biomineralization of hard-shell clams were more complex. Elevated P CO2 (~800-1500μatm) had no significant effects on standard metabolic rates (indicative of the basal energy demand), but affected growth and shell mechanical properties in juvenile clams. Moderate hypercapnia (~800μatm P CO2 ) increased shell and tissue growth and reduced mortality of juvenile clams in high salinity exposures; however, these effects were abolished under the low salinity conditions or at high P CO2 (~1500μatm). Mechanical properties of the shell (measured as microhardness and fracture toughness of the shells) were negatively affected by elevated CO 2 alone or in combination with low salinity, which may have important implications for protection against predators or environmental stressors. Our data indicate that environmental salinity can strongly modulate responses to ocean acidification in hard-shell clams and thus should be taken into account when predicting the effects of ocean acidification on estuarine bivalves. Supplementary material available online at

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“…Among these adaptations, metabolic arrest (a co-ordinated suppression of ATP production and consumption), alternative glycolytic pathways (increasing ATP yield per unit of metabolized substrate and mitigating the metabolic proton load) and high tissue-buffering capacities have been well studied (de Zwaan, 1983;Eberlee and Storey, 1984;Grieshaber et al, 1994;Sokolova et al, 2000a;Sokolova et al, 2000b). In contrast, the potential mechanisms that allow molluscs to preserve mitochondrial capacity during prolonged oxygen deficiency and subsequent reoxygenation are not fully understood.…”

Section: Introductionmentioning

confidence: 99%

Effects of temperature and cadmium exposure on the mitochondria of oysters (Crassostrea virginica) exposed to hypoxia and subsequent reoxygenation

Ivanina

Kurochkin

Leamy

et al. 2012

Journal of Experimental Biology

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SUMMARYIntertidal bivalves are commonly exposed to multiple stressors including periodic hypoxia, temperature fluctuations and pollution, which can strongly affect energy metabolism. We used top-down control and elasticity analyses to determine the interactive effects of intermittent hypoxia, cadmium (Cd) exposure and acute temperature stress on mitochondria of the eastern oyster Crassostrea virginica. Oysters were acclimated at 20°C for 30days in the absence or presence of 50gl -1 Cd and then subjected to a long-term hypoxia (6days at <0.5% O 2 in seawater) followed by normoxic recovery. Mitochondrial function was assessed at the acclimation temperature (20°C), or at elevated temperature (30°C) mimicking acute temperature stress in the intertidal zone. In the absence of Cd or temperature stress, mitochondria of oysters showed high resilience to transient hypoxia. In control oysters at 20°C, hypoxia/reoxygenation induced elevated flux capacity of all three studied mitochondrial subsystems (substrate oxidation, phosphorylation and proton leak) and resulted in a mild depolarization of resting mitochondria. Elevated proton conductance and enhanced capacity of phosphorylation and substrate oxidation subsystems may confer resistance to hypoxia/reoxygenation stress in oyster mitochondria by alleviating production of reactive oxygen species and maintaining high aerobic capacity and ATP synthesis rates during recovery. Exposure to environmental stressors such as Cd and elevated temperatures abolished the putative adaptive responses of the substrate oxidation and phosphorylation subsystems, and strongly enhanced proton leak in mitochondria of oysters subjected to hypoxia/reoxygenation stress. Our findings suggest that Cd exposure and acute temperature stress may lead to the loss of mitochondrial resistance to hypoxia and reoxygenation and thus potentially affect the ability of oysters to survive periodic oxygen deprivation in coastal and estuarine habitats.

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Resistance to freshwater exposure in White Sea Littorina spp. II: Acid-base regulation

Cited by 31 publications

References 30 publications

Effects of environmental hypercapnia and metal (Cd and Cu) exposure on acid-base and metal homeostasis of marine bivalves

Effects of environmental hypercapnia and metal (Cd and Cu) exposure on acid-base and metal homeostasis of marine bivalves

Environmental salinity modulates the effects of elevated CO2 levels on juvenile hard shell clams, Mercenaria mercenaria

Effects of temperature and cadmium exposure on the mitochondria of oysters (Crassostrea virginica) exposed to hypoxia and subsequent reoxygenation

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