AbstractThis article presents the results of studies of the cyanobacteria from foulings of natural and anthropogenic substrates of the intertidal zone of the Kola Bay of the Barents Sea for the period from 2010 to 2019. Ninety-five cyanobacterial species from 46 genera, 20 families, and 6 orders were found; 22 species are given for the first time for the Barents Sea. A majority of cyanobacterial taxa belong to benthic species (70%), which live mainly on natural substrates. The species abundance decreases from the lower intertidal zone to the supralittoral. The proportion of planktonic and bento-planktonic species was 12% and 18%, respectively. Freshwater (44%), marine (37%), brackish-water (3%), and euryhaline (16%) species have been found in the intertidal zone of the bay. The study has revealed 27 indicator species; most of them were oligo- and oligo-betamezosaprobionts. The cyanobacteria of the Kola Bay were predominantly boreal-tropical-notal (26%), cosmopolitan (23%), and boreal (18%) species. Peaks of the number of species were recorded in the early spring (March) and autumn (October). Areas with increased anthropogenic pressure from seaport cities showed the lowest index of species similarity.