Lethal and sublethal effects of ammonia to Penaeus penicillatus juveniles

Abstract

Jiann-Chu Chen and Jin-Nien Lin (1991) Lethal and sublethal effects of ammonia to Penaeus penicillatus juveniles. Bull. Inst. Zool., Academia Sinica 30(2): 73-80. Penaeus penicillatus juveniles were exposed by a static renewal method to different concentrations of ammonia (NH3+NH4+) in seawater at 25 ppt, pH 8.2 and 260C. The 24, 48, 96, 120, 144 and 180 h LC50 of ammonia to P, penicillatus juveniles (0.41 ±0.09g wet weight) were 108, 71.1, 46.6, 43.0, 39.4 and 33.9 mg/t for ammonia-N (un-ionized plus ionized plus ionized ammonia as nitrogen) and 8.16, 5.37, 3.52, 3.25, 2.98 and 2.56 ml/t for NH3-N (un-ionized ammonia as nitrogen), respectively. The e incipient LC50" was 32.0 mg/Z for ammonia-N and 2.42 mg/l for NH3-N from a toxicity curve approaching an asymptote. Relative weight gains of P. penicillatus juveniles (0.20±0.03 g wet weight) exposed to 5 and 10 mg/l ammonia-N (0.38 and 0.76 mg/Z NH3-N) were 123.5% and 58.5%. Relative length increases of P. penicillatus juveniles exposed to 5 and 10 mg/Z ammonia-N were 65.1% and 78.5%, compared to those exposed to the control solution. Based on the eincipient LC50" and an application factor of 0.1, the "safe level" for rearing P. penicillatus juveniles was 3.20 mg/t ammonia-N and 0.24 mg/Z NHa-N. Key words: Penaeus penicillatus, Juveniles, Ammonia, Lethal, Sublethal.將紅尾蝦幼蝦於鹽度25 ppt、pH 8·20及水溫26℃下以靜止換水方式(Static renewal method)暴鰫於不同氨濃度中。氨對於幼蝦( 0.41土0.09 g)之24、48、96、120、144及180小時之(半致死濃度)分別為108、71 · 1、46·6、43·0、39·4及33 · 9 mg/l氨-氮及8· 16、5·37、3·52、3·25及 2·56 mg/t未解離氨qtlncipient LC50”為32·0 mg/l氨一氮及2·42 mg/L未解離氨一氮。暴露於對照組、5及10 mg/L氨一氮240小時後之相對增重率與相對增長率分別為100、123·5及58·5與100、65· 1及78.5。由etincipient LC50”估得培育紅尾蝦幼苗之安全值爲3· 20 mg/l氨一氮, 0· 24 mg/z 未解離氨一氮。