One of the most obvious and long-las ng consequences of the Chornobyl nuclear power plant accident is the crea on of an exclusion zone and a zone of uncondi onal (compulsory) aliena on. The effect of succession is manifested in the fact that a significant part of aqua c and terrestrial ecosystems as of 1986 was ar ficial or semi-ar ficial systems that were under regulatory control by humans. Parasi c systems are one of the informa ve indicators of processes occurring in ecosystems. Any changes in the host popula on lead to changes in the parasite popula on. The degree of imbalance of the "parasite-host" system