Salinity tolerance and morphology of the osmoregulation organs in Cladocera with special reference to Cladocera from the Aral sea

Аладин, Н. В.

doi:10.1007/bf00028407

Cited by 65 publications

(38 citation statements)

References 7 publications

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“…Little information is available, either on the salinity tolerance and osmoregulatory organs in microcrustaceans (Aladin 1991), or on the biological response and adaptations in the freshwater species that invade brackish waters (Arne'r and Koivisto 1993). Freshwater cladocerans are hypertonic to their medium and the fluxes of water and solutes to or from the surrounding water could be considerable, but they have reduced their osmotic load by means of impermeable bodies and a low internal concentration of solutes in the epithelial cytoplasm, from which they are sodium pumped to the hemolymph-the major mechanism for osmoregulation in freshwater cladocerans (Peters 1987).…”

Section: Discussionmentioning

confidence: 99%

“…When salinity causes the medium to become chronically hypertonic with respect to the cladocerans, the available mechanisms for osmoregulation are rather limited, as these species have not developed any evolutionary adaptation to the new conditions. Nevertheless, they are capable of short-term physiological adaptations to minimize the effects of salinization (Aladin 1991).…”

Section: Discussionmentioning

confidence: 99%

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Acute and chronic effects of sodium and potassium on the tropical freshwater cladoceran Pseudosida ramosa

Freitas

2010

Ecotoxicology

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In this study, the toxicities of sodium and potassium to the tropical freshwater cladoceran Pseudosida ramosa were assessed. Acute toxicity tests on this species showed that the 48-h LC(50) of Na(+) was 556 mg l(-1), while that of K(+) was 17.7 mg l(-1). Long-term exposure of female P. ramosa to sodium reduced the total number of survivors from 10 to 6 at a concentration of 249 mg l(-1), 21-day fecundity from 20.4 to 14.3 eggs female(-1) at concentrations ranging from 72 to 249 mg l(-1), 21-day fertility from 20.1 to 6.5 neonates female(-1) at concentrations ranging from 25 to 249 mg l(-1). Furthermore, fecundity of each brood from the second to the fifth was significantly lower at 249 mg l(-1) and fertility of each brood from the first to the fifth at concentrations ranging from 25 to 249 mg l(-1). A significant decrease in fertility was associated with an increase in the number of aborted eggs. Long-term exposure to potassium decreased the 21-day fecundity of P. ramosa from 14.2 to 10.8 eggs female(-1) at a concentration of 11 mg l(-1) and fertility (fourth brood only) at 6.2 and 11 mg l(-1). Tropical reservoirs located near areas where the soil is overloaded with fertilizers and ferti-irrigation with vinasse already show concentrations of Na(+) and K(+) very close to those producing sub-lethal long-term effects on P. ramosa. A possible consequence is that organisms of the aquatic biota cannot adapt and freshwater taxa may become locally extinct, transferring dominance to salt-tolerant taxa.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Acute and chronic effects of sodium and potassium on the tropical freshwater cladoceran Pseudosida ramosa

Freitas

2010

Ecotoxicology

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“…As the genus Daphnia is freshwater in origin and distribution, I did not expect to find reduction in fresh- water adaptation . Since D. magna osmoregulates up to a salinity of about 5%o in the external medium and above this salinity it is an osmoconformer (Fritsche, 1916 ;Aladin, 1991), it seems likely that a reduction in the ability to osmoregulate is involved in the loss of freshwater adaptation . It is sometimes suggested that a trade-off might exist between fitness under favourable conditions and stress resistance (review in Hoffmann & Parsons, 1991) .…”

Section: Comparability Of Data Setsmentioning

confidence: 99%

Effects of salinity on the life history and fitness of Daphnia magna: variability within and between populations

Teschner

1995

Hydrobiologia

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The life history traits of Daphnia magna were studied in laboratory experiments under freshwater and brackish (5%o salinity) conditions . The variability of responses within and between populations was examined by comparing 11 clones from a brackish lake and 10 clones from a freshwater pond . Experimental clones were hatched from ephippia collected from the sediment and thus represent random samples of the clone banks of each population .Most clones with a high salinity tolerance were from the population of the brackish habitat, but some were also found in the freshwater population . Thus, freshwater populations appear to have the potential to invade brackish habitats . A proportion of clones from the brackish population had very low fitness (measured as er) under freshwater conditions . This unexpected result means that freshwater adaptation can be lost by the freshwater cladoceran Daphnia magna . The effects of unfavourable conditions on growth and reproduction varied among clones and were not correlated . This clonal variation in growth and reproduction indicates that the environmental sensitivities of these traits are independent . The pattern of fitness reaction norms showed no trade-off between fitness under brackish and under freshwater conditions for either population . Thus, euryhaline generalists should be favoured in habitats with salinity fluctuations between freshwater and brackish conditions . 33

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“…Many Cladocera, particularly daphnids, do not survive at salinity values above 3-4 per mille (e.g. see Dwyer et al, 1992;Jeppesen et al, 1994) which is what is presently experienced in Hickling Broad in summer, other Cladocera may be more tolerant and there are some which survive at quite high salinities (see Alonso, 1990Alonso, , 1991Aladin, 1991). There also appears to be a great deal of genetically based ecotypic variation within zooplankton species with differential adaptation to local conditions (Weider & Hebert, 1987;Mort, 1991).…”

Section: Very Highmentioning

confidence: 99%

Brackish and freshwater shallow lakes — different systems or variations on the same theme?

Moss

1994

Hydrobiologia

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Saline lakes may be divided into two categories -those primarily saline because they are endorheic and those secondarily saline (brackish) because of natural or anthropomorphic inputs of sea water. Endorheic lakes have greatly varying composition and salinity, occur in arid regions and are not as abundant for that reason as exorheic lakes. The area of land surface over which they are the characteristic types, is, however, very considerable. Many endorheic lakes have communities of low diversity but the reason for this is not necessarily high salinity -the world's largest endorheic lake, the ocean, has a very high diversity -but the temporariness of many of these habitats which has led to wide and unpredictable fluctuations in salinity and to periodic drying out.Secondarily saline lakes are rather different. They generally have an ionic composition which is that of diluted sea water, and although they do not have the high diversity of marine communities, they often have comparable, if slightly lesser, diversities with those of freshwaters. There are no firm salinity boundaries between fresh and brackish waters, only ones drawn (e.g. at 5 per mille total salts) by convention.Brackish waters have the particular interest that estuarine organisms including mysid shrimps and essentially marine members of the algal division, the Haptophyta, may colonize and establish themselves in food webs otherwise characteristic of freshwaters. A comparison is made between the systems of brackish and freshwater lakes in the Norfolk Broadland of eastern England, most of which have undergone eutrophication. Although at first sight appearing very different, both fall into a similar pattern when processes of change are considered. Increases in salinity serve as indirect switch mechanisms which, like other but different mechanisms in freshwaters, may cause the lake community to change from submerged plant dominance to phytoplankton dominance at intermediate states of nutrient loading. The current drought in eastern England is inducing small salinity changes that support this assertion.

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Salinity tolerance and morphology of the osmoregulation organs in Cladocera with special reference to Cladocera from the Aral sea

Cited by 65 publications

References 7 publications

Acute and chronic effects of sodium and potassium on the tropical freshwater cladoceran Pseudosida ramosa

Acute and chronic effects of sodium and potassium on the tropical freshwater cladoceran Pseudosida ramosa

Effects of salinity on the life history and fitness of Daphnia magna: variability within and between populations

Brackish and freshwater shallow lakes — different systems or variations on the same theme?

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