Methodical aspects of using biological monitoring of phytoplankton date for bioindication the water quality in the Volga basin

The possibility of using the quantitative characteristics of the specific variety of phytoplankton for bioindication, obtained by ecological monitoring of fresh waters of Russia is investigated. Retrospective materials on the Volga basin are used. The analysis of following influences on the characteristics of the variety is carried out: 1) errors in the calculation of number of phytoplankton cells; 2) the method of evaluating the parameters of rank distributions; 3) the degree of the adequacy of the formal model of distribution; 4) dependence between the characteristic of evenness of variety and the species diversity; 5) the season of sampling; 6) belonging the samples to one or other subbasin and to the type of water object; 7) transparency and the temperature of water. The characteristics of variety are proposed, which are available data of monitoring. Evaluation of the border between well-being and trouble values of these characteristics is made. The recommendations regarding the application of the variety phytoplankton characteristic of the Volga water quality for bioindication are formulated.