Research of the bottom sediment pollution years-long processes in reservoirs and long-term changes in their water quality based on the diatom analysis and complex bioindication (with Ivankovo Reservoir as example).

Abstract for the application: 

The project aims to develop a new method of assessing the level and pace of reservoir pollution based on the diatom analysis, bioindication methods, correlation analysis and data bases of the hydrological, hydrobiological and hydrochemical observations of reservoirs. The following tasks were achieved within the project:

1.     Conducting expeditions to the Ivankovskoye, Rybinskoye and Klyazminskoye reservoirs for sampling the bottom sediments and carrying out a layer-by-layer analysis of the bottom sediment cores according to the species composition of phytoplankton complexes, organic matter content, biogenic substances, heavy metals and other components in the areas of integral sedimentation on the territory of the reservoirs.

2.     Developing hydrological, hydrobiological and hydrochemical data bases on the monitoring sites of the Ivankovskoye, Rybinskoye and Klyazminskoye reservoirs for the water mass and bottom sediment, and carrying out their spatial-temporal analysis, based on the data received during the expeditions and earlier.

3.     Forming bioindication tables of a new type, based on the unified methods of bioindication and correlation analysis of hydrochemical and hydrological data.

4.     Realizing a graphic analysis of the species structure of diatom complexes from the core samples received during the expedition, in order to assess the years-long transformations of the reservoir ecosystem.

5.     Estimating changes in the anthropogenic pressure on the Ivankovskoye, Rybinskoye and Klyazminskoye reservoirs, based on the spatial-temporal correlations between the diatom complexes in the sediment layers and the structure of phytoplankton associations in the aquatic environment.

6.     Elaborating a new assessment methodology for the geoecological processes of negative transformation of the reservoir’s condition, based on the unified methods of bioindication and correlation analysis of hydrochemical and hydrological data.

Abstract of the report on the project results:

Complex monitoring helped to create a single methodological approach for the ecosystems of the Ivankovskoye, Rybinskoye and Klyazminskoye reservoirs, which implies a comprehensive analysis of the geoecological transformations happening in the reservoir affected by the integral anthropogenic pressure and natural changes.

Besides the traditional forms of chemical and hydrobiological analysis, a tailored innovative method of graphic analysis (MGA) was applied to phytoplankton complexes, while the principle of unified bioindication methods (UBM) was used for the diatom complexes from the sediment cores.

Within the Klyazminskoye reservoir, the MGA helped to establish the main scenarios of transformation of taxonomic proportions in the phytoplankton associations, which were caused by the influence of waters from the Moscow Canal and the annual decrease in the reservoir water level, with planned discharge.

For the ecosystems of Ivankovskoye and Rybinskoye reservoirs, reversible transformation processes in the phytoplankton associations affected by seasonal and climate variability were confirmed. A significant credibility was established for the MGA, defined by the reproducibility of the obtained results.

Despite the different configuration (fig. 1), location and hydrological regime, all the reservoirs revealed a number of similar, disturbing trends.

Fig. 1. A schematic map of the Rybinskoye, Ivankovskoye and Klyazminskoye reservoirs.

Earlier, the UBM had helped to establish a pronounced saprobization and organic matter accumulation in the coastal zones of the Rybinskoye and Ivankovskoye reservoirs (fig. 2).

Fig. 2. Long-term changes in the values of saprobility (S) in the Ivankovskoye (Peretrusovsky bay) and Rybinskoye (Koprino) reservoirs.

In 2019, the sediment layers of the Klyazminskoye reservoir revealed a regular increase in the saprobization level (fig. 3), which is due to the non-linear growth in the number of holidaymakers and increasing recreational pressure (fig. 4).

The second important regularity is a pronounced cumulation of Cu, Zn and other heavy metals in the coastal areas of all the three reservoirs (fig. 5, 6). Similar disruption of ecological balance may become irreversible and bifurcated.

Fig.5. Cu and Zn cumulation in sediment cores from the Ivankovskoye and Rybinskoye reservoirs.

Fig.6. Cu and Li cumulation in a sediment core from the Klyazminskoye reservoir.

The monitoring conducted in 2019, which used innovative methods of bioindication, allows one to most objectively assess the ecological situation on the reservoirs and the processes of long-term transformations happening in their ecosystems. The new methodological approach is based on the conception which implies the analysis of living and non-living components of the Ivankovskoye, Rybinskoye and Klyazminskoye reservoirs as one jointly functioning system.