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Clonal Variation in General Responses of Daphnia magna Straus to Toxic Stress. I. Chronic Life-History Effects

D. J. Baird, I. Barber and P. Calow
Functional Ecology
Vol. 4, No. 3, New Horizons in Ecotoxicology (1990), pp. 399-407
DOI: 10.2307/2389602
Stable URL: http://www.jstor.org/stable/2389602
Page Count: 9
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Clonal Variation in General Responses of Daphnia magna Straus to Toxic Stress. I. Chronic Life-History Effects
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Abstract

Here we compare and contrast responses of different genotypes of the parthenogenetic cladoceran Daphnia magna Straus to cadmium and 3,4-dichloroaniline, under acute and chronic exposure. Our aims have been to document any differences between genotypes in this important and widely used ecotoxicological test species, and to consider their implications for the relative importance of specific vs general responses to toxicants. Large differences in interclonal responses were observed in acute tolerance to cadmium (range of LC50: 0.06 - > 100 p.p.b.). Interclonal variation in chronic stress tolerance was also observed, although in this case differences (though significant) were relatively small (effect concentrations 25-50 p.p.b. for DCA and 0.6-6.0 p.p.b. for cadmium). Deleterious effects on life-history variables and energy allocation followed the same pattern for all clones exposed to both toxicants. We conclude that specific mechanisms dominate differences in acute responses, whereas general mechanisms dominate in chronic responses.

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