Lethal doses of ammonia on Penaeus chinensis larvae

Abstract

Jiann-Chu Chen and Chi-Yuan Lin (1991) Lethal doses of ammonia on Penaeus chinensis Larvae. Bull. Inst. Zool., Academia Sinica 30(4): 289-297. Penaeus chinensis larvae at different developmental stages were exposed to a series of ammonia-N (un-ionized plus ionized ammonia as nitrogen) concentrations in static renewal tOXICIty tests. Larvae at the nauplius stage were the most susceptible, while postlarvae were the most tolerant to ammonia among the larvae tested. The 24-h LCsos were 5.54, 7.42, 20.52 and 30.49 mg/i for ammonia-N and 0.25, 0.34, 1.08 and 1.85 mg/.e for NHs-N (un-ionized ammonia as nitrogen) for the nauplius second substage (N2), the zoea second substage (Z2), the mysis second substage (M2) and the postlarva fourth substage (PL4), respectively in seawater (salinity, 34 ppt; pH, 8.16; and water temperature, 21-25 C C). The 72-h LCsos for M2 and PL4 were 4.05 and 11.98 mg/ i for ammonia-N and 0.21 and 0.73 mg/ i for NHs-N, respectively. The "threshold" was found at 96 h for PL4 on a toxicity curve approaching an asymptote. Based on the "incipient LCso" and an application factor of 0.1, the "safe level," for rearing P. chinensis larvae was estimated to be 0.62 mg/.e for ammonia-N and 0.04 mg/.e for NHs-N in seawater, 34 ppt in salinity, pH 8.16 and 25°C.