Qualitative assessment of algae harmful bloom impact in autumn 2020 off the coast of South-Eastern Kamchatka (North-West Pacific) on shallow-water benthic communities

The results of monitoring of the benthic communities’ state during two years after the ecological catastrophe caused by an outbreak of planktonic microalgae off the coast of Kamchatka in autumn 2020 were presented. The consequences of this phenomenon led to the mass extinction of bottom organisms. As a result, in the zone of the upper sublittoral, a strong depletion of the benthic fauna occurred, not only many species, but also entire groups of animals fell out of its composition: most of the sponges and about a half of species of sea anemones, mollusks, echinoderms, ascidians have disappeared. However, the quantity of some groups of Crustacea has increased significantly.