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Abstract: The Ponto-Azov gastropod mollusk Lithoglyphus naticoides(C. Pfeiffer, 1828) naturalized in the Uglich Reservoir relatively recently (in 2013–2015). The main objective of this study is a comparative analysis of the species diversity and structure of trematode communities in different biotopes occupied by L. naticoidesafter the initial phase of its spread in the upper section of this water body (downstream the city of Dubna), characterized by a complex hydrological regime. The approximate coordinates of the geographical center of the large settlement of L. naticoidesare 56°53′ N, 37°25′ E. It is found that, by 2019–2021, the average density of L. naticoidesin this colony reached a consistently high value of about 450 specimens/m2. Judging by the variability of shell height in adult mature L. naticoidesspecimens, even within the same colony, optimum habitat conditions for this mollusk differ significantly in different biotopes. In a comparative aspect, data from two main hydrobiological sampling locations are considered: in the open part of the reservoir and at the mouth of a large tributary—the Dubna River. It is shown that, at both locations, the species composition of trematodes in L. naticoidesis similar and includes, in particular, parthenitae of Apophallus muehlingi(Jägerskiöld, 1899), Apophallus(=Rossicotrema) donicus(Skrjabin et Lindtrop, 1919), Parasymphylodora markewitschiKulakowskaja, 1947, and Nicolla skrjabini(Iwanitzky, 1928). However, Sanguinicola volgensis(Razin, 1929), dominant in L. naticoidesin the open part of the reservoir, is not found in the sample of mollusks from the mouth of the Dubna River. At the mouth of the Dubna River, compared to the collection point in the open part of the reservoir, the contamination level with parthenitae of other species of trematodes was also significantly lower: for N. skrjabiniand P. markewitschi, it was lower by a factor of 7; for Apophallusspp., by a factor of 8; for Xiphidiocercariasp., by a factor of 13. The ratio of males to females among mature specimens of L. naticoidesturns out to be close to 1 : 1, which is usual for many freshwater mollusks. In general, the high occurrence (the infection prevalence—the proportion of infected specimens in the host sample P± SE, %) in the open part of the reservoir indicates the presence of prerequisites for serious outbreaks of helminthoses: Xiphidiocercariasp. (9.16 ± 2.52%), Apophallusspp. (11.45 ± 2.78%), P. markewitschi(7.63 ± 2.32%), N. skrjabini(7.63 ± 2.32%), S. volgensis(63.36 ± 4.21%). At the same time, according to the data obtained, further spread of L. naticoidesin some tributaries of reservoirs in the Upper Volga basin may not have such serious parasitological consequences. |
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