Dependence of pH values in the digestive tract of freshwater fishes on some abiotic and biotic factors

• Published in: Hydrobiologia Vol. 807; no. 1; pp. 67 - 85
• Main Authors: Solovyev, M. M., Izvekova, G. I., Kashinskaya, E. N., Gisbert, E.
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.02.2018; Springer; Springer Nature B.V
• Subjects: Analysis; Biomedical and Life Sciences; Biotic factors; Carassius gibelio; Catostomus catostomus; Coregonus lavaretus; Coregonus migratorius; Cyprinus carpio; Digestive system; Digestive tract; Ecology; Ecosystem components; Enzymes; Feeding; Fish; Fishes; Freshwater; Freshwater & Marine Ecology; Freshwater fish; Freshwater fishes; Habits; Hydrogen ions; Inland water environment; Intestine; Intestines; Lakes; Leuciscus leuciscus; Life Sciences; Perca fluviatilis; pH effects; Primary Research Paper; Regulatory mechanisms (biology); Rutilus rutilus; Species; Temperature effects; Water temperature; Zoology; pH; Temperature; Feeding habits; Freshwater fishes; Digestive tract
• ISSN: 0018-8158; 1573-5117
• DOI: 10.1007/s10750-017-3383-0

The values of pH in the digestive tracts of 20 freshwater fish species inhabiting various Russian Federation waterbodies were studied. Only in six species ( Coregonus lavaretus , Coregonus migratorius , Catostomus catostomus , Carassius gibelio , Rutilus rutilus, Leuciscus leuciscus ) out of 20 species, the differences in pH values between different regions of the intestine were significant. Feeding habits, feeding frequency, and gut fullness in fish affected pH values. Temperature was one of the most important factors affecting pH values. During cold seasons (spring and fall; average water temperature: 8–10 and 5–6 ○ C, respectively), the pH values in fish guts were higher than that in the summer seasons(water temperature 22–25°C) for C. gibelio , Perca fluviatilis , Cyprinus carpio , L. leuciscus, and R. rutilus from the Chany Lake. Similar results (lower pH values in intestine at higher water temperatures) were also obtained for C. gibelio in warmer years in comparison to colder years in the same waterbody and in L. leuciscus and P. fluviatilis in the different waterbodies with different water temperatures. It is hypothesized that dependence of pH in fish gut on temperature may serve as a regulatory mechanism for maintaining the activities of hydrolytic enzymes at the required level for their successful functioning.