Activity of digestive enzymes in the small intestine Black-legged kittiwakes <i>Rissa tridactyla</i>, nesting on the coast of the Barents Sea

The black-legged kittiwakes Rissa tridactyla nesting on the Murmansk coast of the Barents Sea have been studied. The activity of digestive enzymes (aminopeptidase N, maltase and sucrase) in the mucosa of the small intestine of birds was measured. The composition of the feeds of the black-legged kittiwakes was determined by the contents of their stomachs. Capelin, juvenile cod and crustaceans made up their diet. Capelin and crustaceans have been recorded in the diet of females, while males mainly have cod. Comparative analysis showed that the values of digestive enzyme activity had no significant differences in females and males. An increase in the activity of sucrase in the mucosa of the small intestine was recorded in birds in whose stomachs otoliths of cod, capelin and crustacean remains were found, compared with the activity of digestive enzymes in birds with empty stomachs. The species composition of helminths parasitizing in the small intestine of black-legged kittiwakes has been established, and their invasion rates have been calculated. The cestodes Alcataenia larina and Tetrabothrius erostris have been recorded in the proximal section of the small intestine of birds. In places of localization A. larina increased the activity of aminopeptidase N and decreased the activity of maltase relative to the indicators of uninfected black-legged kittiwakes.