Effect of endosulfan on oxygen equilibrium curves of blood of food fish <i>Oreochromis mossambicus </i>(Peters)

Abstract

Oxygen equilibrium curves of the blood of the control <i>O.mossambicus </i>was sigmoid and P₅₀ and 'n' values were 12.5 mm Hg and 3.57 respectively. Upon exposure to sub-lethal and lethal concentrations of endosulfan the oxygen equilibrium curves of the blood moved to the right. Thus, the P₅₀ value in the treated fish tended to increase signifying the reduction in the affinity of the pigment for oxygen. A decrease in blood <i>p</i>H due to increase in CO₂ content was noticed. This caused increase in P₅₀ and consequent shifting of oxygen equilibrium curves to the right in the endosulfan treated fish and showed the

existence of normal or negative Bohr effect. Thus endosulfan exposure causes not only the direct harmful effects on the fish, but also the indirect effect on gas exchange property of blood.