[Short Note] Lethal Concentration of Nitrite on Penaeus chinensis Larvae
Sha-Yen Cheng
Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan 202, R.O.C.
Jiann-Chu Chen
Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan 202, R.O.C.
Penaeus chinensis larvae at the nauplius stage are the most susceptible, while postlarvae are the most tolerant to nitrite. The 24 hr LC50s were 23.12,56.34,73.61, and 67.71 mg/l nitrite-N for nauplius third substage (N3), zoea second substage (Z2), mysis second substage (M2), and postlarva twelfth substage (PL12), respectively in 30 ppt seawater at pH 8.21 ± 0.03. The "threshold time" was found to be 108 hr for PL12 on a toxicity curve approaching an asymptote. Based on the "incipient LC50" and an application factor of 0.1, the "safe level" for rearing P. chinensis larvae is estimated to be 1.38 mg/l nitrite-N.
Keywords
Penaeus chinen sis, Nitrite, Toxicity
