The fauna and benthic communities of invertebrates of the Ural river within the Atuar steppe (Orenburg state nature reserve)

There are 70 species and forms in the composition of zoobenthos of the river Ural and in water bodies of its floodplain have been identified. Mayflies and chironomids are represented in various ways (13 and 12 species and forms, respectively). Caddisflies (10) and stone flies (7) are rich in species. Among other invertebrates, bivalves (6) and gastropods (5), small-bristled worms (5), non-chironomid dipterans (4), leeches, crustaceans and dragonflies, bugs and beetles were recorded. On sandy-gravel-pebble soils is formed a zoobenthocenosis, dominated by the mayflies Ephoron virgo. They are accompanied by Chironomidae larvae. The biomass of the community varies between of 29.32–31.68 g/m2 with an abundance of 18.1–32.44 thousand ind./m2. In the coastal of the channel is formed a pelophilic zoobenthocenosis, the basis of it abundance and biomass are constituted by the small-bristle worms Limnodrilus hoffmeisteri. They are accompanied by mollusks Stagnicola palustris and mysids P. lacustris. The biomass of the pelophilic community is 13.68 g/m2 with a population of 15.45 thousand ind./m2. In floodplain water bodies are formed pelophilic zoobenthocenoses, the biomass of which varies in the range of 19.2–34.24 g/m2 with an abundance of 5.64–30.04 thousand ind./m2. Chironomid larvae constitute the base of the population. The biomass is composed by dragonflies Libellula sp., Chironomids, and mollusks Bithynia tentaculata.

Changes of malacofauna in a small lowland river in eastern Poland

In 2016, the species composition and the structure of the dominance of molluscs in the Muchawka River (left-bank tributary of the Liwiec River) were assessed. The occurrence of 19 species of molluscs were recorded, including 11 species of snails and 8 species of mussels. The eudominant was Pisidium casertanum, which, only in the last two sites, constituted 43.1% of all molluscs. Two other species of molluscs from the Sphaeriidae family were also eudominants – Pisidium subtruncatum (22.8%) and Sphaerium corneum (10.3%). Snails were most frequently represented by the dominant Bithynia tentaculata, constituting 5.4% of all molluscs, and the subdominant Bathyomphalus contortus at 2.8%. Sixteen years after the first malacological analysis, an increase in species richness and differences in the dominance of molluscs were found in the Muchawka River. Clams from the Sphaeriidae family invariably dominated but with a different species composition. The disappearance of the protected Anodonta cygnea and Sphaerium rivicola has been noted, and the occurrence of the protected Unio crassus has also been noted.

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.

Morphobiological characteristics of trematode cercariae of the families Opisthorchiidae and Notocotylidae

The results of studying the body structure of trematode cercariae of the families Opisthorchiidae and Notocotylidae and the features of their development in Western Siberia are presented. The data of long-term (1994–2019) studies on the spread of these pathogens of dangerous parasitic diseases in humans and animals are analyzed and summarized. The studies were conducted according to generally accepted methods in parasitology and hydrobiology. The species affi liation of trematodes was determined in laboratory conditions on mature cercariae that independently left the shells of the host mollusks Bithynia tentaculata and B. troscheli. It was noted that the trematodes of the Opisthorchiidae and Notocotylidae families at the cercaria stage have the following similar features: a simple tail, pigmented eyes, and one oral sucking cup. Diagnosis of trematode cercariae of Opisthorchiidae and Notocotylidae families is possible by the following signs: the tail of the opisthorchis cercaria has a swimming membrane and is 2 times longer than the body, the tail of the notocotylid has no swimming membrane and is approximately equal in length to the body. Opisthor-chis cercariae have two pigment eyes, notocotilids – three. In the life cycle of opisthorchis, there are two intermediate hosts (bitinia and fi sh), in the notocotylid cycle, one (bitinia). Opisthorchis cercariae have penetration glands, but notocotylids do not; the maximum daily emission of opisthorchis cercariae is ten times higher than that of notocotylids (6672 and 422 cercariae, respectively). The ability to diagnose opisthorchis and notocotilid at the cercaria stage allows the identifi cation of local foci of epidemiologically and epizootically dangerous diseases.

High parasite diversity in a neglected host: larval trematodes of Bithynia tentaculata in Central Europe

Bithynids snails are a widespread group of molluscs in European freshwater systems. However, not much information is available on trematode communities from molluscs of this family. Here, we investigate the trematode diversity of Bithynia tentaculata, based on molecular and morphological data. A total of 682 snails from the rivers Lippe and Rhine in North Rhine-Westphalia, Germany, and 121 B. tentaculata from Curonian Lagoon, Lithuania were screened for infections with digeneans. In total, B. tentaculata showed a trematode prevalence of 12.9% and 14%, respectively. The phylogenetic analyses based on 55 novel sequences for 36 isolates demonstrated a high diversity of digeneans. Analyses of the molecular and morphological data revealed a species-rich trematode fauna, comprising 20 species, belonging to ten families. Interestingly, the larval trematode community of B. tentaculata shows little overlap with the well-studied trematode fauna of lymnaeids and planorbids, and some of the detected species (Echinochasmus beleocephalus and E. coaxatus) constitute first records for B. tentaculata in Central Europe. Our study revealed an abundant, diverse and distinct trematode fauna in B. tentaculata, which highlights the need for further research on this so far understudied host–parasite system. Therefore, we might currently be underestimating the ecological roles of several parasite communities of non-pulmonate snail host families in European fresh waters.

Features of the first intermediary host distribution of Opisthorchis felineus near the major cities of KhMAO–Ugra (Western Siberia)

In this paper the dynamics of invasion extensiveness of freshwater Bithyniidae snails by trematodes Opisthorchis felineus (cat fluke) in the waters of Khanty-Mansi Autonomous Area was determined. The study was conducted for the Ob river (Surgut) and the Irtysh river (Khanty-Mansiysk) for 7 years. As a result of the study, it was determined that the population density of snails and the extensiveness of their invasion by O. felineus trematodes are higher in the Irtysh River, which is associated with the hydrological regime of the river. Indicators of invasion extensiveness are higher for Bithynia tentaculata snails than Bithynia troscheli.