Uvaeva O. Mollusks of the family Viviparidae (Gastropoda, Pectinibranchia): structural and functional organization of populations, bioindication potential and role as purifying agents in water bodies of Ukrainian Polyssia

For the first time, long-term data are collected on age, size and sex ratio dynamics of population structure of Viviparus viviparus (Linnaeus, 1758) and V. contectus (Millet, 1813) in waters of Ukrainian Polyssia. A sharp decline in numbers, biomass characteristics and occurrence of Viviparidae was recorded recently. The most probable reasons are climate change and the anthropogenic pressure that alters their environment. In waters of Ukrainian Polyssia, maximum age is five years for V. viviparus mollusks and six years for V. contectus. For the first time, the quantitative estimation of life expectancy and morbidity coefficient is developed based on population characteristics of river snails. The linear growth characteristics and environmental influence on populations of river snails of Ukrainian Polyssia are studied. The annual production of Viviparidae is characterized according to mass (total, shell, and raw, dried and decarbonized tissues) and P/B coefficient. The resulting multiple regression equations allow determining various characteristics of annual production of V. viviparus by standard hydrobiological indices, such as population density and biomass. Average mass and average shell height of mature (2 to 3 year old) snails, and sex ratio in populations of V. viviparus are the population characteristics which are the most informative in bioindication with this species. Filtration and sedimentation rates of V. viviparus and V. contectus are estimated experimentally. The abiotic (concentration of suspension, pH, temperature), biotic (trematode infection) and anthropogenic (ions of heavy metals and synthetic detergents) factors influence the purification potential of river snails. Ions of heavy metals and synthetic detergents are shown to suppress filtration activity of V. contectus. Those potential water pollutants are dangerous for filtration activity of snails and subsequently for self-purification potential of their ecosystems. Viviparus contectus is shown to promote reduction of organic matter in water with simultaneous enrichment the bottom layer.