Seasonal changes in pH values in the intestine of fish from Lake Chany (West Siberia)

The pH values are determined in the digestive tract of nine fish species in Lake Chany (West Siberia). Seasonal changes in pH values are found along the intestine of fish. Intestinal pH values decrease in summer as the temperature rises and increase during the cold season as the temperature drops. The hypothesis has been advanced that temperature-dependent pH changes in the intestine may serve as a regulatory mechanism that maintains the activity of hydrolytic enzymes at the level required for successful digestive processes due to some adaptive modifications of the medium where these enzymes operate.