The XI All-Russian school-seminar for young scientists, students, and postgraduates “Modern hydrobiology: Global problems of the World Ocean”, organized by IBSS Council of young scientists, took place on 28 September – 02 October 2020. All the events were held online. Participants got acquainted with the research on fundamental bases of hydrobionts adaptation to environmental changes, problems of conservation and rational use of marine biological resources, perspective directions of marine biotechnology and aquaculture, and methodology and organization of operational control of Black Sea biota and coastal ecosystems. More than 30 participants and listeners took part in the work of the school-seminar. A book of proceedings is uploaded in the national bibliographic database Russian Science Citation Index.