Influence of Nitrite and Chloride Concentrations on Survival and Hematological Profiles of Striped Bass

Abstract

The 24-h median lethal concentration of nitrite (NO₂ ^–) for striped bass Morone saxatilis was 163 mg/L in static toxicity tests. Exogenous chloride ions increased the tolerance of the fish for NO₂ ^–; CaCl₂ was more than twice as effective as NaCl. Plasma NO₂ ^–, cortisol, and methemoglobin were correlated positively with environmental NO₂ ^–. Plasma NO₂ ^– and methemoglobin were correlated negatively with environmental Cl^–, but cortisol was not reduced by the presence of environmental Cl^–. Striped bass maintained NO₂ ^– in the plasma (0–45 mg NO₂ ^–/L) at concentrations below those in the environment (0–250 mg NO₂ ^–/L). However, striped bass were sensitive to NO₂ ^– that entered the plasma; methemoglobin levels greater than 60% and plasma NO₂ ^–, levels greater than 70 mg/L resulted in significant mortalities.