Oxygen consumption, ammonia excretion and osmoregulation of callinectes similis Juveniles (Crustacea: Portunidae) exposed to fluctuating salinities

Abstract

The oxygen consumption of Callinectes similis was determined under salinity fluctuations. The metabolic rate remained unchanged (P > 0.05) and within a metabolic range of 1.23 to 2.08 mg O2.h–l.g–l D.W., exhibiting a type IV response according to Kinne (1971). Ammonia excretion rose significantly to 0.028 mg N-NH4.h–l.g–l D.W. (P 0.05) by osmotic stress. In high salinities catabolism is based on carbohydrates and in lower salinities on a mixture of lipids and carbohydrates. The osmoregulatory pattern exhibited by C. similis is of an osmoconforming organism, the hemolymph was only slightly hyperosmotic in higher and isosmotic in lower salinities.

Keywords

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