Validation of 22 Sodium Turnover in Estimating Sodium and Food Intake in an Amphibian (Bufo marinus)

We measured the relationship between the amount of sodium ingested by 10 adult toads (Bufo marinus) and the turnover rate of tracer amounts of 22sodium injected into each animal. There was a good relationship (r2 = 0.76) with the isotope turnover technique overestimating measured sodium intake by approximately 9%. We suggest that reliable estimates of food consumption can be obtained in free-living amphibians using this technique, provided the sodium content of the diet and the extent of transdermal sodium influx are known.