Osmotic Regulation in Freshwater Animals

Potts, W. T. W.; Parry, Gwyneth

doi:10.1016/b978-0-08-013598-4.50010-9

Cited by 35 publications

(19 citation statements)

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“…Previous stud- ies have suggested that Acartia tonsa could only weakly (if at all) regulate extracellular water balance at salinities below 31, but the evidence is inconclusive (Lance 1965). In our experiments, respiration did not increase with decreasing salinity, revealing that osmoregulation represented, at most, only a small fraction of the energy budget, as has been observed for other crustaceans (0.4 and 1.3% in Astacus and Eriochir, respectively; Potts 1954, Schmidt-Nielsen 1991, and for the copepod Eurytemora affinis (Roddie et al 1984).…”

Section: Salinity Effects On Acartia Tonsa Energy Partitioningmentioning

confidence: 43%

Salinity modulates the energy balance and reproductive success of co-occurring copepods Acartia tonsa and A. clausi in different ways

Calliari¹,

Andersen²,

Thor³

et al. 2006

Mar. Ecol. Prog. Ser.

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We assessed metabolic balance, RNA content, and egg hatching success (EHS) in Acartia tonsa and A. clausi over a wide salinity range (2 to 33 and 16 to 33, respectively). For A. tonsa, the energy partitioning between ingestion, production and respiration was relatively constant with small differences in gross growth efficiency (GGE) and cost of growth (CG). In contrast, A. clausi exhibited significantly reduced ingestion and GGE, and highly elevated CG at salinities ≤20. In both species, RNA levels mirrored egg production. EHS was generally high in both species, but decreased by 80% for A. clausi at 16. These results contribute to the understanding of distribution patterns of both species along salinity gradients. The observed responses would allow the dominance of A. tonsa at low salinities, although its higher energetic requirement and feeding activity subject it to stronger predation pressure than competing A. clausi.

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Section: Salinity Effects On Acartia Tonsa Energy Partitioningmentioning

confidence: 43%

Salinity modulates the energy balance and reproductive success of co-occurring copepods Acartia tonsa and A. clausi in different ways

Calliari¹,

Andersen²,

Thor³

et al. 2006

Mar. Ecol. Prog. Ser.

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“…occurs at salinities below 10 to 12 Ym S (Oglesby et al, 1982;Quinn and Bashor, 1982), but the increased ventilation requirement cannot solely be due to increased demands for active ion transport. Potts (1954) showed that the energetic cost of ionic and osmotic regulation is low, accounting for only a small part of the observed oxygen consumption in marine invertebrates.…”

Section: Discussionmentioning

confidence: 99%

Ventilation and oxygen uptake by three species of Nereis (Annelida: Polychaeta). II. Effects of temperature and salinity changes

Kristensen¹

1983

Mar. Ecol. Prog. Ser.

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Ventilation and oxygen uptake of Nereis virens, N. succinea and N. diversicolor were monitored during changing temperatures (5.5 to 37.5 "C) and salinities (1.7 to 24.0 % S). Measurements were performed using a direct flow sensing technique with worms in polyethylene tubes simulating natural conditions. Ventilation amplitude increased with temperature (Qlo = 2.6 to 2.9) for the 3 species, reaching well defined species specific upper limits. This is assumed to be the upper limit for Nereis ventilation capacity. At temperatures above 30 to 35 "C, but below the lethal limit, ventilation decreased and eventually ceased. Oxygen uptake during active periods appeared to increase with temperature over the range measured (Qlo = 1.3 to 2.2). Ventilation requirement showed minimum values at species specific temperatures, suggesting optimum temperatures at the present acclimation level (N. virens, 11 to 20 'C; N. succinea 20 to 35 "C and, N. diversicolor, 5 to 16 " C ) . Reduction in salinity resulted in a decreased ventilation amplitude, possibly due to osmotic swelling of the worms. Oxygen uptake during active periods was quite unaffected by salinity changes. Ventilation requirement increased for all 3 species at low salinities and was most pronounced in the stenohaline N. virens and least in the euryhaline N. diversicolor. The observed responses to temperature and salinity changes are also related to distributional patterns of the 3 species in a Danish estuary.

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“…All rights reserved. 1522-2152/2005/7803-4031$15.00 stant internal ion concentration in a hypoionic environment relies on mechanisms for reducing diffusive loss of ions and/ or ensuring efficient scavenging of ions from the dilute medium (Potts and Parry 1964). Consequently, most osmoregulating freshwater animals devote considerable resources toward the active uptake of ions, such as sodium, across the transport surfaces.…”

Section: Introductionmentioning

confidence: 99%

Humic Substances Influence Sodium Metabolism in the Freshwater CrustaceanDaphnia magna

Glover

Pane

Wood

2005

Physiological and Biochemical Zoology

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Humic substances are ubiquitous components of natural waters with important roles in alleviating metal toxicity to aquatic organisms. Recent literature reports suggest that humic substances may also exert direct influences on biota. This study investigated the influence of two commercially available humic substances on sodium metabolism in Daphnia magna, a hyperregulating freshwater crustacean. Environmentally realistic levels of Suwannee River natural organic matter (SRN) and Aldrich humic acid (AHA) significantly enhanced sodium transport. This effect was described as an uncompetitive stimulation of sodium influx, as characterised by an increased maximal sodium transport rate (Jmax), accompanied by a decreased uptake affinity (increased Km). SRN exposure also significantly promoted the unidirectional loss of sodium from the daphnids to the water, an effect not observed in the presence of AHA. A 24-h preexposure to AHA before influx measurement had no effect on AHA-induced stimulation of sodium influx. Conversely, 24-h preexposure to SRN resulted in influx values that returned to control (humic-free) levels. Whole-body sodium levels reduced by SRN exposure were also restored to control levels following 24-h SRN preexposure. The significance and potential mechanisms of these actions are discussed, and the toxicological implications of these findings are assessed.

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Osmotic Regulation in Freshwater Animals

Cited by 35 publications

References 0 publications

Salinity modulates the energy balance and reproductive success of co-occurring copepods Acartia tonsa and A. clausi in different ways

Salinity modulates the energy balance and reproductive success of co-occurring copepods Acartia tonsa and A. clausi in different ways

Ventilation and oxygen uptake by three species of Nereis (Annelida: Polychaeta). II. Effects of temperature and salinity changes

Humic Substances Influence Sodium Metabolism in the Freshwater CrustaceanDaphnia magna

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