Date of Award


Document Type


Degree Name

Master of Science




Evidence from this study suggests that Na++K+-activated ATPase is involved in the ionic regulation of sodium in the hemo-lymph of the blue crab in low salinity environments. The time course of changes in gill Na++K+-ATPase specific activity follow- ing transfer of crabs from JO o/oo to 5 o/oo salinity indicates that a major increase in activity occurred within 2.5-3.0 hr. Apparently, a 8.8-11.1% decrease in hemolymph sodium ion concen-tration to about J55-J60 meq/1 in approximately 2-J hr was sufficient to activate the ATPase cation transport system in the gills of Callinectes sapidus. Following enzymatic activation, hemolymph sodium concentration gradually approached stabilization at 270-J10 meq/1 within 24 hr. Acclimation to high salinity (30 o/oo)occurred within 2 hr after transfer from 5 o/oo salinity.

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