STUDY OF THE CONTENT OF CERTAIN HEAVY METALS IN THE SOFT TISSUE OF THE (VIVIPARUS VIVIPARUS L.) THAT INHABITATES THE RIVER OF SOZH IN GOMEL

The soft tissues of molluscs are the components that make it possible to establish the degree of influence of the urban agglomeration on the pollution of the components of the aquatic ecosystem, which do not have a visible anthropogenic load, with compounds of heavy metals. The content of the heavy metals under investigations (except for nickel) decreased in comparison with the data obtained in 2002, which indicates a decrease in anthropogenic load on the aquatic ecosystems of the Sozh. The high content of copper, cobalt and nickel before the city’s wastewater is received confirms the influx of pollutants with the surface runoff of agro-residential areas and settlements located upstream of the city along the river. Unidirectional decrease in copper concentration downstream of the Sozh testifies to the course of ecosystem self-cleaning processes. Confirmation of these processes is a significant decrease in the content of lead and chromium in the area outside the city, in comparison with the section of the river within the city limits. The abnormally high concentration of lead and chromium in the soft tissues of Viviparus viviparus L. in the river section within the city limits, nickel and cobalt below the city limits, indicates the flow of metals into the river with the surface runoff of the city. The high level of metal content in the old complex shows the need to conduct a study on the content of pollutants in aquatic ecosystems that do not have a visible anthropogenic load, but are used by the population for recreational purposes.

Sexual dimorphism in shell morphology of mollusks of the genus Viviparus – important objects of water resources of Ukraine

Bioindication assessment of water bodies of Ukraine can be carried out using the ratio of males and females of mollusks of the genus Viviparus. In practice, it is very convenient to determine the sex of mollusks by the differences in their shell. Male and female freshwater snails Viviparus viviparus (Linnaeus, 1758) and V. contectus (Millet, 1813) are shown to have reliable differences in shell morphology depending on their age. There is almost no sexual dimorphism by shell morphometrics and indices in Viviparus snails aged one to three years. After three years of life, mature females have significantly larger shell width, higher body whorl, and size of the aperture. Females of V. viviparus at the age of two to five years may be differentiated from males by the relationship of mean shell width and shell height, which is statistically significant higher than in males. This difference is explained by the different size of the mantle section genital organs of mature male and female. The obtained results should be taken into consideration in establishing the sex of viviparid snails.

ТРЕМАТОДОФАУНА ЧЕРЕВОНОГИХ МОЛЮСКІВ (GASTROPODA) ВЕРХІВ’Я КИЇВСЬКОГО ВОДОСХОВИЩА

Our study aimed to examine the current state of trematodes diversity in Kyiv reservoir. The molluscs under analysis belong to the species living for more than two years. The presence of trematode invasion in molluscs indicates the permanent or periodic presence of infected vertebrate hosts in area. Low mobility of the molluscs contributes to specification of the specific reservoir section visited by the definitive hosts. The species composition and quantitative indicators of invasion of the larval stages (cercariae) of trematodes (Digenea) in six species of Gastropoda in the Dnieper area of the upper site of Kyiv reservoir were studied. In total up to 490 specimens of Gastropoda belonging to subclasses Pulmonata (Lymnaea stagnalis Linnaeus, 1758, Planorbarius corneus Linnaeus, 1758, Stagnicola palustris Muller, 1774) and Prosobranchia (Fagotia acicularis Férussac, 1823, Viviparus viviparus Linnaeus, 1758, Bithynia tentaculata Linnaeus, 1758) were examined. The largest number of trematodes species was found in molluscs L. stagnalis (Lymnaeidae) and B. tentaculata (Bithyniidae) which amounted to seven and three species accordingly. The highest abundance, 150 and upper per mollusc specimen, were Diplostomum spathaceum (Rudolphi, 1819) and Tylodelphys conifer (Mehlis, 1846). Three species of trematodes were recorded in B. tentaculata − Cercaria lophocerca Filippi, 1857, Pleurogenoides medians (Olsson, 1876), Palaeorchis incognitus Szidat, 1943 with an average abundance upper 280 and prevalence 8−17%. Basically, the definitive hosts of the detected species of trematodes are fish, amphibians and waterfowl. Detected cercariae of trematodes D. spathaceum, Sanguinicola intermedia Ejsmont, 1925, Metagonimus yokogawai (Katsurada, 1912), Echinostoma revolutum (Fröhlich, 1802), Echinoparyphium recurvatum (Linstow, 1873) may cause diseases and sometimes death of fish and waterfowl. Some species may be used in medicine.

Стабильные изотопы углерода и азота в органическом матриксе раковин чужеродных моллюсков Viviparus viviparus (Linnaeus, 1758) Новосибирского водохранилища

Анализ стабильных изотопов углерода и азота широко используется в экологических исследованиях для изучения структуры трофических сетей, оценки роли различных ресурсов в питании отдельных особей, определении трофического уровня консументов. Раковина у моллюсков постепенно формируется в течение всей жизни и отражает особенности питания особей в разном возрасте. Проведены исследования стабильных изотопов углерода и азота раковин чужеродных моллюсков Viviparus viviparus (Linnaeus, 1758), собранных в Новосибирском водохранилище. Отмечены статистически значимые различия изотопного состава фрагментов раковин, соответствующих годичному приросту разных лет. Высказано предположение о значимой роли межгодовых различий трофических условий в водохранилище в формировании изотопной подписи раковин моллюсков. Результаты работы могут быть использованы в экологических и палеолимнологических исследованиях питания моллюсков, при реконструкции долговременных изменений экологических условий водоемов.

Age and size characteristics of alien mollusks Viviparus viviparus L. in the coastal thanatocoenosis of Novosibirsk reservoir

Viviparus viviparus L. is the most numerous alien species of the Novosibirsk reservoir. In some parts of the reservoir V. viviparus creates settlements with a very high density. After the death of mollusks in the bottom sediments and on the banks of the reservoir, large areas of accumulation of empty shells are formed. Due to their strong structure, the shells are poorly decomposed and can serve as a generalized indicator of the state of the mollusk population over a long time. We analyzed the size and age characteristics of the V. viviparus shells in thanatocenoses of the Novosibirsk reservoir coast. Empty shells of river snails were collected on the shores of the middle (near the village of Chingis, Ordynskoye and in the Karakansky Bay) and the lower (near the village of Borovoye, Bystrovka, Leninsky and in the Berdsky Bay) parts of the Novosibirsk Reservoir in May, 24–26, 2018. Shells height and width were measured with an electronic caliper with an accuracy of 0.1 mm. Age of mollusks was determined by the marks of a winter growth stop on the shell. It is shown that in the thanatocenoses of the middle part and in the bays of the reservoir, shells of young mollusks (the second and third years of life) prevailed. In the lower part of the reservoir, the coastal thanatocoenosis contained larger shells of adult mollusks (fourth and fifth years of life). In general, the most of V. viviparus individuals in the Novosibirsk reservoir die before they reach the age limit. It is suggested that the premature death of most river snails can be caused by significant seasonal fluctuations in the water level of the reservoir, during which the littoral is drained.