Hydrolysis of carbohydrates in roach (Rutilus rutilus (L.)) at different levels of mercury accumulation

It has been shown that chronic exposure to dietary mercury results in the intensive accumulation of this metal in roach yearlings. The concentrations of accumulated mercury in their organisms were proportional to the amount of metal added to water of experimental tanks. Increased Hg content in the organisms (0.05–0.16 mg/kg) of developing juvenile roaches decreases the activity of digestive carbohydrases and the affinity of enzymes to substrate with subsequent retardation of rates of initial stages of digestion. The accumulation of mercury in the organism is accompanied by an increase in the body length and weight in the exposed fish compared to the control. The possible mechanisms responsible for such an increase in fish with high Hg body burdens, and with a simultaneous decrease in carbohydrate metabolism rate, are discussed in the paper.