Since 2002 we carry out the monitoring of the Black Sea algal viruses. More than 200 variants of viruses of five algae species (Tetraselmis viridis, Phaeodactilum tricornutum, Dunaliella viridis, Prorocentrum pusilla and Isochrysis galbana) were isolated. For searching Black Sea algal viruses and studying their properties some new methods and techniques have been developed. In our experiments for the first time the viruses from the land have been adapted to the marine environment and to a new host - microalgae. A new fact - the presence of algal viruses in clinical material have been revealed, suggesting a previously unknown ways of marine viruses circulation. The hypothesis of virus circulation between the land and the hydrosphere was substantiated and announced. The study of dynamics of virus and DNA solution contact in microcalorimetry, and detection of viral titer reduction by orders of magnitude in the presence of nucleotides were the basis for the hypothesis of the nucleic acids role and their decay products in the regulation of viral lyses in hydrosphere. The analysis of genomes of Black sea algae viruses showed a cosmopolitan combination of genes and their unique set.