JUSTIFICATION FOR THE NECESSITY OF REGISTRATIONIN THE RED DATA BOOK OF UKRAINE THE UNIO CRASSUS PHILIPSSON, 1788 (MOLLUSCA, BIVALVIA, UNIONIDAE)

Abstract

The article substantiates the necessity of registration in the Red Data Book of Ukraine the Unio crassus Philipsson, 1788 – a mollusk, which is an indicator of water purity and an important factor of self-purification of hydro-ecosystems. As a result of monitoring studies, 300 species of Unionidae-like biotopes within all river basins of Ukraine during the period 1993-2018 have been marked with a sharp reduction of the species distribution area. Mollusk has become quite rare in the basins of the Siverskyi Donets, Dniester, Dnieper, Southern Bug, Crimea rivers, and it has not been detected at all in the hydrocenoses of the Western Bug, although in the 40-60s of the last century it was considered to be a widespread species in these regions. Its occurrence in modern reservoirs of Ukraine is only 15 %. The most common Unio crassus in the Prypiat basin (41 % occurrence) U. crassus is a rheophilic species found only in rivers. Given the overall degradation of the country’s aquatic ecosystems, the tendency to reduce the occurrence of U. crassus may intensify, which is why it is important to undertake appropriate environmental measures in a timely manner aimed at preserving the malacofauna of water basins and streams of Ukraine. In due course, this species should be listed in the Red Data Book of Ukraine with the status of “vulnerable”.