Estimation of Water Turnover Rate in Captive Dugongs (<I>Dugong dugon)</I>

Abstract

Water turnover rate was measured for two captive dugongs (Dugong dugon) using deuterated water. Body water content of 69.5% in a dugong was high compared to other marine mammals. A water turnover of 257.2 ml kg -1 day -1 measured in one dugong was almost twice as high as the highest rates measured in studies of captive West Indian manatees (Trichechus manatus) and was high compared to those measured in carnivorous marine mammals. The other dugong’s estimated water turnover rate of 134 ml kg -1 day -1 was comparable to the highest rates in manatees. Two alternative explanations are offered for the high water turnover: (1) the incidence of mariposia or voluntary drinking of sea water by the dugong or (2) a metabolic rate that is significantly higher than predicted, based on its phylogeny.