title: 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 
journal: BIOLOGY & ECOLOGY