The state of three populations of the adventitious species H. pomatia was studied on the basis of conchiometric, phenetic and genetic methods. According to the obtained data, the two newly described populations from the Belgorod and Lugansk regions differ both in metric and morphological indicators, as well as in the frequencies of alleles of isoenzyme loci. The reason for such disparity may be genetic-automatic processes, natural selection in newly developed territories, as well as chaotic invasion from various localities, either from native range, or from nearby biotopes.

The predatory gastropod mollusk Rapana venosa is included in the list of the 100 most dangerous invasive species of the Black and Mediterranean Seas, which determines the relevance of studying the species’ local populations in the areas of introduction. The first studied Rapa whelk population in Donuzlav Bay (NW Crimea) was one of the last to form and differs from populations in other areas of the Black Sea. Based on the results of studies in 2020, the characteristics of the population structure of R. venosa inhabiting the Donuzlav Bay and the adjacent marine area are shown. The data obtained are compared with the population characteristics of the Rapa whelk from other areas of the Black Sea. It is shown that at the stage of stabilization of the metapopulation, the phenotype of the adapted “norm” R. venosa of the Black Sea was formed.