Nitrite is a common pollutant in water and is highly toxic to aquatic animals. To reveal the mechanism of salinity in attenuating nitrite toxicity to fish, we measured the physiological responses of juvenile Takifugu obscurus exposed to nitrite concentrations (0, 10, 20, 50, and 100 mg/L) under different salinity levels (0, 10, and 20 ppt) for 96 h. Salinity increased the survival rates of juvenile T. obscurus exposed to nitrite. Changes in key hematological parameters, antioxidant system, malondialdehyde, Na⁺/K⁺–ATPase, and HSP70 indicated that nitrite induced considerable damage to juveniles; salinity mitigated the harmful effects. This finding reflects similar changing trends in both antioxidants and their gene expressions among different tissues. We applied an overall index, an integrated biomarker response (IBR), that increased under high−nitrite condition but recovered to the normal levels under salinity treatment. Analysis of the selected detection indices and IBR values showed that the overall mitigating effect of salinity on nitrite toxicity seems to be at sub-cellular level and associated with complicated physiological responses.

亚硝酸盐是水中的常见污染物，对水生动物有剧毒。为了揭示盐度的机制在衰减亚硝酸盐对鱼类的毒性，我们测量少年的生理反应暗纹东方鲀暴露于亚硝酸盐的浓度（0，10，20，50，和100毫克/升）在不同的盐度水平（0，10，和20 ppt），持续96小时。盐度提高了暴露于亚硝酸盐下的暗色T. obscurus的成活率。关键血液学参数，抗氧化剂系统，丙二醛，Na ⁺ / K ^+的变化–ATPase和HSP70表明亚硝酸盐对少年造成了相当大的损害；盐度减轻了有害影响。这一发现反映了抗氧化剂及其基因表达在不同组织之间的相似变化趋势。我们应用了整体指标，即综合生物标志物响应（IBR），该指标在高亚硝酸盐条件下增加，但在盐度处理下恢复到正常水平。对所选检测指标和IBR值的分析表明，盐度对亚硝酸盐毒性的总体缓解作用似乎在亚细胞水平上，并且与复杂的生理反应有关。