http://scipeople.ru/publication/66775/; Ostroumov S.A. The concept of aquatic biota as a labile and vulnerable component of the water self-purification system.-Doklady Biological Sciences, Vol. 372, 2000, pp. 286–289. Translated from Doklady Akademii Nauk, Vol. 372, No. 2, 2000, pp. 279–282. ABSTRACT. A new fundamental concept of the role of biota in the functioning of aquatic ecosystems is proposed. According to that concept, the complex of aquatic organisms (aquatic biota) is a central, labile and potentially vulnerable component of the water self-purification system in aquatic ecosystems. This fundamental concept leads to substantial changes in the hierarchy of priorities for protection of biodiversity and environment. According to the concept suggested in this work, the maximum allowable concentrations (MACs) for specific substances should be established after taking into account the possible effects of pollutants on the water self-purification system. Possible effects on many organisms, including filter feeders, should be taken into consideration. Both inhibiting and stimulating effects of sublethal concentrations of pollutants are dangerous, because either of them may cause an imbalance in the complicated system of water self-purification. The fundamental concept suggested in this work heightens the level of priority of the sublethal effects of pollutants. The sublethal effects leading to changes in the functional activity of populations of aquatic organisms may cause an imbalance in the system of water self-purification. --KEY WORDS: new fundamental concept, role of biota, functioning of aquatic ecosystems, central, labile and potentially vulnerable component, water self-purification, priorities for protection of biodiversity and environment, maximum allowable concentrations, MACs, substances, filter feeders, inhibiting and stimulating effects, sublethal concentrations, pollutants, hazards, imbalance, sublethal effects, functional activity, populations, bivalves, sodium dodecylsulphate, Triton X-100; SDS, TX-100, water filtration, phytoplankton, Mytilus edulis; TDTMA, tetradecyltrimethylammonium bromide, Brachionus angularis, cyanobacteria, green algae, diatom algae, flagellata, vascular plants , invertebrates, synthetic surfactants, pesticides, suspended particles, sedimentation, sorption, evaporation, hydrolysis, photochemical conversion, catalytic redox conversion, free radical reactions, contaminant, toxicity, binding to dissolved organic compounds, DOCs, chemical oxidation, biogens, hydrobionts, biotransformation, redox reactions, destruction, conjugation, extracellular enzymatic transformation, pellets, bottom; ---http://scipeople.ru/users/2943391/; [http://www.springer.com/life+sci/journal/10630] also see: http://sites.google.com/site/bioeffectsofsurfactants/ http://sites.google.com/site/surfactantinhibitfilterfeed02/ http://sites.google.com/site/3surfactantsfiltrationmytilus/ http://sites.google.com/site/ostroumovsergei/ http://sites.google.com/site/bioticupgradewaterquality2008/