| Abstract: | Rangia cuneata (Gray, 1832), an estuarine lamellibranch of the marine family Mactridae, is found in areas subject to salinity fluctuations ranging between 0 and 25°/oo. As adults these clams are capable of surviving several months in freshwater and at least two months in full-strength seawater. The present study was conducted to determine the effect of environmental salinity variation on selected physiological parameters. At salinities of 5°/oo or less Rangia responds by maintaining its blood osmotic concentration at approximately 60 m0sm/liter above the medium. Uptake of dissolved glycine is sharply reduced at salinities below 5°/oo, but between 6 and 25°/oo there was no significant difference in the rate of glycine uptake by whole animals or isolated gill tissue. ... |
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