BlOُNERGET‘lC OF OSMOREGULATION IN Liza abu .JUVINlLES DURING SALINITY .ACCUMULATION

Abstract

Several physiological variables related to salinity acclimation in Liza abu wereexamined, using oxygen consumption rate and glucose level as an indication ofosmoregulatory energetic. l~'reshwater acclimated I.. aim were transferred to two salinity (7and 15 g/L) oxygen consumption rates. glucose levels and plasma ion concentrations (Na i.K’) were measured after three days of transfer to higher salinity. Plasma ion concentrationswere elevated after transfer. Blood glucose level increased after transfer to salinity 7 g/Lwhile its level decreased in salinity 15 g/L compared to its level in freshwater. Oxygenconsumption rate increased one and half time of that in freshwater but no significantdifference were noticed in oxygen consumption rates between fish in both salinities (7 and15 g/L) .'l'he amount of metabolic energy consumed during salinity acclimation were alsodetermined. The result showed that the physiological changes associated with salinityacclimation impose a significant short - term energetic cost.