Lethal Effect of Nitrite on Metapenaeus ensis Larvae

Abstract

Metupenaeus ensis larvae at different stages were exposed to a series of nitrite-N (nitrite as nitrogen) concentrations in static renewal toxicity tests. Larvae at zoea stage were the most susceptible, and postlarvae were the most tolerant to nitrite among the larvae tested. The 24 h LC50s were 31.29, 16.05, 47.60 and 70.06 mg/L nitrite-N for third nauplius substage (N3). second zoea substage (Z2), second mysis stage (M2), and first postlarva substage (PL1), respectively, in 33 ppt seawater at a pH of 8.20 and a water temperature of 30 C. The 48 h LC50 for M2 and PL1 were 20.67 and 27.10 mg/L nitrite-N, respectively. The “threshold time” was 108 h, and the “incipient LC50” for M. ensis PL1 was 7.06 mg/L nitrite-N. A “safe level” for rearing M. ensis larvae was estimated to be 0.71 mg/L nitrite-N in the hatchery.