Physiological pH values in the digestive tract of perch <Emphasis Type="Italic">Perca fluviatilis</Emphasis> from different habitats

Physiological pH values are determined in the gastrointestinal tract of the perch Perca fluviatilis from lakes Chany and Baikal. Values of pH are detected to vary significantly along the digestive tract. Such factors as a segment of the digestive tract, presence/absence of food, season of the year, and habitat affect pH values. Environmental temperature is the main factor affecting pH values that is confirmed by the decrease in pH values upon water temperature rise in spring, lower pH values in summer compared to other seasons, and lower pH in fish from the waterbody (Lake Chany) with higher temperature of water.     

Diversity of microbial communities of the intestinal mucosa and intestinal contents of fish from Lake Chany (Western Siberia)

The diversity of microbial communities associated with the intestinal mucosa and the intestinal contents of fish with different nutritional profiles have been investigated. Differences in the intestinal microbiota of fish with different dietary preferences have been revealed using group-specific primers for the main large taxa of bacteria. Representatives of the phyla Planctomycetes, Vernicomicrobia, and Cyanobacteria have been detected in the intestinal contents of all investigated nonpredatory (crucian carp, roach, and dace) and predatory (pikeperch, pike, and perch) fish. Representatives of the phylum Firmicutes were detected in the intestinal mucosa and intestinal contents of predatory fish species, but not in those of the nonpredatory fish.     

Variability of Composition of Microbiota of Gastrointestinal Tract of Perch Perca fluviatilis and Prussian Carp Carassius gibelio During the Vegetative Season

Journal of Ichthyology - The composition of the microbiota of the digestive tract of two fish species differing in feeding habits—perch Perca fluviatilis and Prussian carp Carassius gibelio...     

Infection with metacercaria of the family diplostomidae and activity of digesting enzymes of the young of the Siberian dace <Emphasis Type="Italic">Leuciscus leuciscus baicalensis</Emphasis> (Dyb.) in the Kargat River of the basin of Lake Chany

In 2008 and 2009 on the Kargat River (basin of Lake Chany) we studied activity of the intestinal digestive enzymes (general activity of proteases, α-amilase, nonspecific esterases and pancreatic lipase) of the young of the Siberian dace Leuciscus leuciscus baicalensis (Dyb.) infected with metacercaria of the family Diplostomidae. The relation between the intensity of the invasion with metacercaria of the family Diplostomidae and activity of the intestinal digestive hydrolases was studied. The negative correlation of the activity of the digestive enzymes and the intensity of the invasion with metacercaria both in various segments and in the whole intestine was revealed.     

Feeding habits and ontogenic changes in digestive enzyme patterns in five freshwater teleosts

Feeding habits and the activity of digestive enzymes (total alkaline proteases, α‐amylase and lipase) from dace Leuciscus leuciscus, roach Rutilus rutilus, Prussian carp Carassius auratus gibelio, perch Perca fluviatilis and pikeperch Sander lucioperca fry were studied in the Malye Chany Lake–Kargat Estuary (western Siberia, Russia). The diet of fry from all studied species was mainly composed of chironomid larvae and zooplanktonic organisms (i.e. cladocera and copepoda), whereas carnivorous species such as P. fluviatilis and S. lucioperca also preyed on fry from other fishes while detritus and microalgae were also important in the diet of ommivorous species. When comparing diet similarity (Sørensen–Dice index, Q_S) among fry at different stages of development, both omnivorous and carnivorous species showed a high level of similarity (0·67 < Q_S < 0·89 and 0·73 < Q_S < 0·89, respectively). Diet similarity values were in agreement with the overall digestive activity profile analysed by cluster analysis. Diet similarity suggested potential trophic competition when zooplanktonic and benthic prey began to decline towards autumn. The analysis of pancreatic digestive enzymes revealed a correlation among their activities and fry feeding habits with α‐amylase:total proteases (A:P) values higher than 1 in omnivorous species and lower (A:P ≤ 1) in carnivorous species.