Krystian Obolewski

Shallow lakes, including those located at the border between Europe and Asia (Kazakhstan), have become very prone to increasing salinity because of climate change. Most of the study area is in one of the fastest-warming parts of the globe. Our research, conducted in four lakes varying in water salinity level and located in western Kazakhstan in the steppe, semi-desert, and desert zones, can be used to predict biodiversity as indicators of the natural potential of ecosystems. This was achieved by assessing the associations of invertebrate communities with environmental conditions based on data collected during nine seasonal measurement campaigns (in May, July, and September of 2019, 2020, and 2021). The multidimensional scaling (nMDS) of biotic and abiotic data enabled us to identify lakes as freshwater (1), oligohaline (1), and mesohaline (2). The key classifier was biotope salinity, irrespective of lake location in the steppe, semi-desert, or desert zones. Twenty-nine taxa were identified in the freshwater lake, 37 in the oligohaline, and 24-28 in the mesohaline lake; these accounted for similar to 80% of their estimated taxonomic composition, according to Species Accumulation Curves (SAC). The differences in the structure of benthic invertebrate assemblages revealed between the lakes are mainly concerned with the density and, to a lesser extent, the diversity of communities (Simpson index). As the salinity of the waters increased, the proportion of Diptera larvae significantly increased, and that of Ephemeroptera larvae decreased. Sigara assimilis, accompanied by Sphaeromas sp., Chironomus sp., and Saeharia sp., proved strongly resistant to increased water salinity. Among the studied lakes, the semi-desert lake Balykty Sarkyl (beta-mesohaline) is strongly threatened by biodiversity degradation due to unfavourable climatic conditions. Time series analysis for Lake Edilsor (alpha-mesohaline) shows that it underwent the most rapid salinisation, which has increased the number of taxa tolerant to this predictor (mainly Diptera larvae). The results confirm that detailed taxonomic assessment (including time series) can significantly improve our understanding of lake changes with increasing salinity caused by climate change and/or other stressors.

We present a unique data set of selected physicochemical parameters characterizing the environment of the Baltic coastal lakes within Polish borders. The peculiarity of the system derives principally from the interaction of the lakes with a sea of relatively low salinity. In contrast to our best understanding of the state of biological knowledge, the abiotic parameters of coastal lakes along the southern Baltic Sea have never previously been so comprehensively supplemented. The database consists of physicochemical properties of 13 coastal lakes based on the analytical assessment of 419 water samples collected seasonally between 2014 and 2019. Water properties were analyzed according to the connection of the lakes to the Baltic Sea using a total of 23 predictors. The lakes were classified as closed, intermittently connected, or open. Based on the physicochemical data, a relationship between the hydrological connection between the lakes and the sea was determined. The data collected could be used to monitor ongoing global climate change at the biosphere level.

Decisions to build or remove dams and other large engineered hydraulic infrastructures are always entangled in social and environmental impacts, which are often evaluated formally through bureaucratic processes. In Europe dam removals are relatively infrequent, even though extensive hydraulic infrastructure has degraded biodiversity and water quality. The Wilkówka dam in southern Poland was required to be removed rapidly, primarily due to engineering failures during its construction. Using survey methods, we examine the local community's perceptions of the net environmental and social impacts of the Wilkówka dam removal. In surveying the opinions of households, 62% of respondents expressed that decisions about the removal were taken without sufficient community consultation, and 92% felt that the dam had been removed despite their opposition. Although the dam had been built recently and had failed to operate at design capacity, respondents reported strong attachments to the services they perceived it to provide, including water supply, flood regulation and cultural significance. In spite of the possibility of an environmental disaster and long‐term environmental degradation, most surveyed households would have preferred it to have been renovated or reconstructed. In short, the removal of the Wilkówka dam was perceived by local households but also by local officials as bringing about a net loss in socially relevant ecosystem services, despite the urgent need for removal perceived by regional and national authorities. The local community's rapid attachment to the dam despite its potential negative impacts on biodiversity and the local environment were primarily attributable to the high expectations as to the hydrological services that the dam was to provide (water supply, flood regulation and its larger symbolic value as an infrastructural investment in the community). This work provides an empirical demonstration of the importance of understanding the social, ecological and technological context within decision‐making processes regarding dam removals, and its implications may improve the planning and implementation of future dam removal projects.

The objective of the study was to determine the relationship between the structure of phytocenoses in riparian wetland ecosystems and the hydrologic regime in a lowland river floodplain. The hydrobotanical study was conducted over three years—2017, 2018, and 2019—which differed in hydrological conditions (wet, average, and dry) in a middle section of the Supraśl floodplain (NE Poland) as a case study. The results showed that the structure and pattern of phytocenoses in the floodplain are primarily controlled by the hydrological regime of the river and the geomorphological features of the area. The reach and duration of the flood contributed to a specific pattern of riparian vegetation. Based on the plant community structure and riparian habitat indicators such as soil moisture, fertility, reaction pH, soil granulometry, and organic matter content, four habitat types were identified and supported by linear discriminant analysis (LDA): wet, semi-wet, semi-dry, and dry zones. The indicator species analysis (ISA) revealed species characteristic of the zones with the dominance of reed rush, reed canary grass, anthropogenic or partially natural herbaceous communities along watercourses or riparian meadows, respectively. Natural inundation of the river water is an important driver of site-specific vegetation elements and habitat types and determines habitat availability, biodiversity, and ecosystem functions of wetlands. This knowledge can serve as the basis for conservation efforts, sustainable management practices, and decision-making processes aimed at maintaining the biodiversity and ecological integrity of riparian ecosystems in similar regions.

The objective of the study was to determine the relationship between the structure of phytocenoses in riparian wetland ecosystems and the hydrologic regime in a lowland river floodplain. The hydrobotanical study was conducted over three years 2017, 2018, and 2019, which differed in hydrological conditions (wet, average, and dry) in a middle section of the Supraśl floodplain (NE Poland) as a case study. The results showed that the structure and pattern of phytocenoses in the floodplain are primarily controlled by hydrological regime of the river and the geomorphological features of the area. The reach and duration of the flood contributed to a specific pattern of riparian vegetation. Based on plant community structure and riparian habitat indicators such as soil moisture, fertility, reaction pH, soil granulometry, and organic matter content, four habitat types were identified and supported by discriminant analysis (DA): wet, semi-wet, semi-dry, and dry zones. The indicator species analysis (ISA) revealed species characteristic of the zones with the dominance of reed rush, reed canary grass, anthropogenic or partially natural herbaceous communities along watercourses or riparian meadows, respectively. Natural inundation of the river water is an important driver of site-specific vegetation elements and habitat types and determines habitat availability, biodiversity, and ecosystem functions of wetlands. This knowledge can serve as the basis for conservation efforts, sustainable management practices, and decision-making processes aimed at maintaining the biodiversity and ecological integrity of riparian ecosystems in similar regions.