The results of ecotoxicological monitoring - studies of the resistance of marine phytoplankton communities of the Arctic seas to some pollutants are presented. The influence of pollutants on primary productivity was assessed as the most sensitive biological process. It is shown that the method of ecotoxicological sounding makes it possible to identify areas most susceptible to chronic pollution, leading to a decrease in biological productivity.

The results of the study of the quantitative relationships between solar radiation (integral radiation and PAR), the content of nutrients, and the spring bloom parameters in the Ucha Reservoir are presented. Positive significant correlations between the date of peak bloom and the sum of light intensity over the period from the 35the to the 40th days (the upper reaches of the reservoir, station Pestovo) and the period from the 44th to the 49th days (the lower reaches of the reservoir, station Listvyanka) were determined on the basis of a retrospective analysis of the data from the period of 1993–2003. Regression equations were derived, which permit forecasting the start of phytoplankton growth in spring according to the results of solar radiation measurements. The sum of light intensity over the course of 50 calendar days in each years correlate positively with the phytoplankton abundance in spring (the highest daily number of algae and integral estimation of algae number in spring).

The ecotoxicological investigations on the resistance of various phytoplankton communities were performed in the Southern Baltic Sea during summer and winter periods. The primary production rate was studied for different Cu concentrations. The enhancement of the toxic effect as well as total biomass and productivity increase were observed for phytocenosis. Total algae biomass on most of the stations increased accordingly to the dinoflagellate growth. Both dinoflagellate impact and relative copper toxic effect declined in the Gdansk Bay opposite to the high total algae biomass observed. We assume the dinoflagellate abundance is linked with the sensitivity of the phytoplankton cells to copper.

An experimental-analytical method for assessing the vulnerability of aquatic ecosystems under conditions of anthropogenic pollution is considered. Such data are very important for estimating economic damage from accidental environmental pollution and determining the seasons in which industrial activities will be less hazardous in ecological terms. A feasible approach to this problem is based on the study of ecosystem behavior under critical conditions. Phytoplankton, being the main primary producer of organic matter in the aquatic ecosystem, is the key element providing for its stability.

A new method of working up results of factorial toxicological experiments is put forward and illustrated by a number of examples. It is based on the profound comparison of values of reactions as consequences of toxic influence and aimed at revealing the combinations of toxicant concentrations that break the monotonous character of a surface which graphically depicts the effect of pollutants. The geometrical analysis allows us to have a new vision of numerous results of factorial experiments, gives some complimentary possibilities for quantitative evaluation of impact of pollutants by mean of surface diagrams and for experimental assessment of environmental parameters of natural communities.