The composition of the diatom assemblages was analysed in four rivers of Upper Silesia, Poland in 2017. The diatom assemblages studied were found to reflect anthropogenic salinization caused by mining activities. The assemblages in those river...

Background: Secondary salinity of river water reduces the value of ecosystem services, negatively impacting the entire aquatic ecosystem and reducing the possibility of water use. In Poland, significant anthropogenic salinity of rivers and water reservoirs is usually associated with mining activity consisting of pumping salty mine water into settling ponds or often directly into rivers. However, to assess the reasons for the salinity of the Vistula waters, it is necessary to identify all sources of salt in surface waters, enabling the assessment of the salt load in the waters. Methods: The paper presents four sources of data which have been compiled to propose a valuable method for analyzing the threat of the river. Patrol monitoring was one method of data acquisition, and State Environmental Monitoring data ware also used. Clustering and correlation statistical techniques were used for analysis. Results: Of the 20 physical and chemical parameters analyzed, chloride, calcium sulphate and magnesium ions are important for salinity. Measurements with multi-parameter probes allowed for the identification of increased salinity pressure sites, while flow analyses were required to calculate the load. Conclusions: The Vistula River had the highest concentrations of the analyzed ions in the Silesia Region. The use of patrol monitoring can be highly useful in determining the causes of emerging problems with water quality and supporting State Environmental Monitoring.

The ecological assessment of rivers under the Water Framework Directive (WFD) requires the use of biological quality elements (BQEs) across defined abiotic types of rivers. However, limited evidence exists on how well biological indices perform across multiple typological classes, particularly under the influence of complex, overlapping stressors. This study evaluated the diagnostic performance of four biological indices (IO—diatoms, MIR—macrophytes, MMI_PL—benthic macroinvertebrates, and EFI + PL—fish) in 16 river sites in southern Poland. These were classified into four abiotic types (5, 6, 12, and 17) and subjected to varying levels of human pressure. Biological, physical and chemical, and hydromorphological data were collected along environmental gradients including conductivity, nutrient enrichment, and habitat modification. Statistical analyses were used to evaluate patterns in community composition and index responsiveness. The IO and MMI_PL indices were the most consistent and sensitive in distinguishing between reference and degraded river conditions. MIR and EFI + PL were more variable, especially in lowland rivers, and showed stronger associations with habitat structure and oxygen levels. Conductivity emerged as a key driver of biological responses across all BQEs, with clear taxonomical shifts observed. The results support the need to consider both typological context and local environmental variation in ecological classification. The findings underscore the need for typology-aware, pressure-specific biomonitoring strategies that combine multiple organism groups and integrate continuous environmental variables. Such approaches can enhance the ecological realism and diagnostic accuracy of river assessment systems, supporting more effective water resource management across diverse hydroecological contexts.