Home – Home – Jornals – Contemporary Problems of Ecology 2019 number 2

In the last decades, besides the comparatively well-studied “bloom” caused by phytoplankton, a “bloom” of marine and fresh waters caused by littoral benthic macroalgae of three genera: Ulva , Cladophora and Spirogyra have become a global phenomenon. In the present review, an attempt is made to approach a comprehension why namely these taxa of green filamentous algae start to grow rapidly in spring in many water bodies and streams, including oligotrophic waters, and then float up from bottom forming floating mats (metaphyton), and their decaying masses are washed ashore and cause substantial ecological and economical losses. Peculiar and common ecological and physiological features of Ulva , Cladophora and Spirogyra favorable for the “green tides” formation are considered. Although an eutrophication (supply of nitrogen and phosphorus from agricultural lands, industrial and domestic wastewaters, aquaculture) is the evident cause of the increase of algal biomass, a hypothesis is proposed that a location of external fluxes of inorganic nutrients (surface runoff or groundwater discharge) is of the key importance for the “green tides” formation, as well as a biogenic re-direction of internal fluxes of nitrogen and phosphorus from pelagial to littoral (benthification). Measures of mitigation of “green tides” are discussed. A necessity of detailed study of metaphytonic form of vegetation of benthic macroalgae is emphasized. It is remarked that a revision of the present concept of oligotrophic/eutrophic waters, which considers only pelagic compartments of aquatic ecosystems is needed.