VULNERABLE SPECIES OF BIVALVE MOLLUSCS PSEUDANODONTA COMPLANATA IN THE FAUNA OF UKRAINE: DISTRIBUTION, STATE OF SETTLEMENTS

Abstract

Bivalve molluscs of the family Unionidae are important components of freshwater ecosystems, as they are active filterers and shape the quality of water in their habitats. Due to anthropogenic transformation of water bodies, this group of animals is recognized as one of the most vulnerable. The paper analyzes the dynamics of the frequency of occurrence and the state of Pseudanodonta complanata Rossmassler, 1835 populations over the last 100 years in Ukraine. This species of Unionidae is protected in many European countries, it was  included  in  the  Red  Data Book  of Ukraine in 2021 with the status "vulnerable". Three  different time periods  were chosen  to  analyze the distribution of P. complanata, the state of its populations in Ukraine and possible dynamics of changes. To establish the population characteristics of the species  in  water  bodies  about 100-50 years ago, an analysis was carried out based on the study  of  collections  of  shells  of  the  species stored in museums of the country and literature sources. To analyze the state of P. complanata populations in the second time interval, the results of our own collections carried out during 2007- 2012 within all river basins of Ukraine were chosen. In total, 300 sites were surveyed during this period. The third period of analysis covered the results of our own collections within the Central (Zhytomyr) Polissia in 2019-2022, 57 potential habitats of Unionidae were surveyed in the reservoirs and watercourses of the Teteriv, Sluch, Uzh and Ubort basins. In Ukraine, until the 70-80s of the twentieth century. P.complanata, despite its sporadic distribution, was quite widespread species. During the study period of 2007-2012, P. complanata was not recorded in the basin of the Western Bug, upper and lower Southern Bug, lower Dnipro, reservoirs of the Dnipro cascade, upper Siverskyi Donets and rivers of Azov and Crimea. In the collections of 2019-2022, the species was not found in any point. The results confirm the need to protect the vulnerable species and further develop conservation measures.