Acute toxicity of nitrite nitrogen to planktonic larvae and juveiles of Manila clam Ruditapes philippinarum
CHEN Zhen-nan， LIU Nian， ZHANG Yue-huan， PAN Fa-lin， HUO Zhong-ming， YANG Feng
College of Fisheries and Life Science, Engineering Research Center of Shellfish Culture and Breeding in Liaoning Province, Dalian Ocean University, Dalian 116023, China;South China Sea Institute of Oceanology, Chinese Academy of Sciences,Guangzhou 510301,China;Jilin Institute of Fishery Sciences, Changchun 130033,China
Abstract: Acute toxicity of nitrite nitrogen(NO2-N) to juveniles of Manila clam Ruditapes philippinarum with shell length of(9.4-10.3) mm at different pH(7.2, 7.6, 8.0, 8.4) and to planktonic larvae with shell length of(162.2±15.9)μm were investigated in a laboratory in order to investigate the toxicity of nitrite nitrogen to Manila clam. It was found that the 96 h LC50 of NO2-N was 160.5 mg/L in planktonic larvae at natural seawater pH(8.00±0.20), water temperature of(26.1±0.6)℃,and salinity of 23, with poor growth as the prolongation of stress time and the increase in NO2-N concentration. At 48 hours, there was no significant difference in shell length and shell height between≤146.8 mg/L group and control group(P>0.05). The planktonic larvae exposed to under 97.8 mg/L stress for 96 hours had decrease by 10.0% in shell length and by 11.3% in shell height(P<0.05) and by 14.4% in shell length and by 14.7% in shell height at 144 h exposure(P<0.05). The 96 h LC50 of NO2-N was found to be 628.1 mg/L in juvenile clam under the conditions of pH(7.97±0.07), water temperature of(19.9±0.3)℃ and salinity of 30, with decrease in toxicity of nitrite with the increase in pH, and 96 h LC50 of 497.0 mg/L at pH 7.6, and 628.1 mg/L at pH 8.0 and 1062.0 mg/L at pH 8.4. The results indicate that the toxicity of NO2-N can be reduced by appropriate increase in pH in aquaculture practices since both planktonic larvae and juvenile calm have strong tolerance to NO2-N, especially juveniles.
2019, Vol. 34 
