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Sodium balance in the green turtle,Chelonia mydas, in seawater and freshwater

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Summary

Sodium balance in the green turtle,Chelonia mydas, has been investigated in both seawater and freshwater. In seawater the unidirectional Na efflux is 131 μM · 100 g−1 · h−1, over 90% of which is via the head region and less than 5% each is via the cloaca and the integument. After 17 days in freshwater the efflux of Na has declined by 97% and the majority is via the cloaca. The integumental efflux in freshwater is less than that in seawater indicating that a change in skin permeability, trans-skin electrical potential or pattern of blood flow has taken place. Although there are indications that Na is actively extracted from freshwater by the green turtle, this species faces a net loss of Na of the medium and the blood Na concentration falls significantly. When transferred from seawater to freshwater the turtle's orbital salt gland is turned off within 25 h after transfer. The salt gland does not become functional until 400 h after transfer from freshwater to seawater.

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Authors and Affiliations

  1. Dept. of Biology, University of Miami, 33124, Coral Gables, Florida, USA

    Thomas A. Kooistra & David H. Evans

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  1. Thomas A. Kooistra
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  2. David H. Evans
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Kooistra, T.A., Evans, D.H. Sodium balance in the green turtle,Chelonia mydas, in seawater and freshwater. J Comp Physiol B 107, 229–240 (1976). https://doi.org/10.1007/BF00691228

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  • DOI: https://doi.org/10.1007/BF00691228

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