Application of effective microorganisms for Littoral zone restoration in eutrophic reservoirs

Inland waters play an important ecological, social, and economic role. However, they are exposed to various types of pollution, mainly from agriculture, industry, and urbanization. Therefore, it is important to take measures to restore their biological balance by supporting the natural processes of bioremediation. One of the methods for such measures is the use of effective microorganisms (EM). The objectives of this study are therefore: (i) to verify the temporal and spatial variability of the results of microbiological parameters (total heterotrophic bacteria - HBN, microscopic fungi - MF, coliform count - CI, dehydrogenase activity - DHA) in the sandy littoral substrate (beach) collected within the eutrophic Turawa reservoir (Southern Poland, Central Europe); ii) comparison of the results of microbiological parameters at control points and during the application of EM (spraying the shore surface with a liquid bio-preparation); iii) verification of the effectiveness of EM on the microbiological parameters of the substrate collected in the coastal zone of the reservoir and comparison with the results from other studies. The statistical analyses performed (PCA, HCA, correlation matrix) showed a high relationship and correlation (R from 0.88 to 0.92) between the study points and discrepancies between the parameters tested. Statistical significance was demonstrated for CI when the group of control points was compared with EM application - there was an average decrease in CI of 48% after EM application (decrease from 6.31 · 10^-3 g to 3.28 · 10^-3 g). The results obtained were consistent with the literature for HBN and MF (an increase of 14.74 and 10.81 medians in the group with EM application; 0.07045 · 10⁶ CFU/g and 0.205 · 10³ CFU/g, respectively) and differed for DHA (decrease, marginal difference, i.e. 2.41%; 41.5 mg TPF/kg·h). The results described represent one of the case studies related to the bioremediation of water reservoirs and the improvement of sanitary safety in the vicinity of water reservoirs. The research fits into strategies for rational land management governed by numerous national and international legal acts, strategies, and policies.