Acute toxicity of ammonia on Litopenaeus vannamei Boone juveniles at different salinity levels

Yong-Chin Lin, Jiann-Chu Chen-2001

Journal of Experimental Marine Biology and Ecology, 259(1): 109-119

Abstract:

Litopenaeus vannamei juveniles (total length 22±2.4 mm) were exposed to different concentrations of ammonia-N (un-ionized plus ionized ammonia as nitrogen), using the static renewal method at different salinity levels of 15 ppt, 25 ppt and 35 ppt at pH 8.05 and 23°C. The 24, 48, 72, 96 h LC50 values of ammonia-N on L. vannamei juveniles were 59.72, 40.58, 32.15, 24.39 mg l^-1 at 15 ppt; 66.38, 48.83, 43.17, 35.4 mg l^-1 at 25 ppt; 68.75, 53.84, 44.93, 39.54 mg l^-1 at 35 ppt, respectively. The 24, 48, 72, 96 h LC50 values of NH₃-N (un-ionized ammonia as nitrogen) were 2.95, 2.00, 1.59, 1.20 mg l^-1 at 15 ppt; 2.93, 2.16, 1.91, 1.57 mg l^-1 at 25 ppt; 2.78, 2.18, 1.82, 1.60 mg l^-1 at 35 ppt, respectively. As the salinity decreased from 35 ppt to 15 ppt, susceptibility of ammonia-N increased by 115%, 132%, 140% and 162% after 24, 48, 72 and 96 h exposure, respectively. The "safety level" for rearing L. vannamei juveniles was estimated to be 2.44, 3.55, 3.95 mg l^-1 for ammonia-N and 0.12, 0.16, 0.16 mg l^-1 for NH₃-N in 15 ppt, 25 ppt and 35 ppt, respectively.

(Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan, 202, Tel.: +886-2-2462-2192 ext. 5205; fax: +886-2-2462-0295, e-mail of Jiann-Chu Chen: Jcchen@mail.ntou.edu.tw)

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