EFFECT OF AMMONIA ON SURVIVAL AND ADENYLATE ENERGY-CHARGE IN THE SHRIMP PALAEMONETES VARIANS

Shrimps Palaemonetes varians were submitted to lethal and sublethal co ncentrations of ammonia in order to measure lethality, ATP and adenyla te nucleotide levels, and adenylate energy charge (AEC) index. LC50 wa s of about 3 mg/liter of ammonia. Adenylate measurements were performe d over a period of 14 days and for two different concentrations. A pop ulation submitted to 0.5 mg/liter of ammonia exhibited high survival a nd a marked consumption of ATP, whereas high mortality and disordered ATP metabolism are the characteristics of the population submitted to 3 mg/liter of ammonia. An homeostatic model was applied in order to ex plain the significance of the AEC signal. Here, AEC is proposed as a m easure of the limits of active response of an organism to environmenta l stress. (C) 1996 Academic Press, Inc.