A new paper by a team of ecologists from the Department of Ecology and Nature Protection has just been published, complementing a series of articles dedicated to the restoration of aquatic ecosystems in the Carpathians and their foothills. The research results have been published over the past three years in renowned journals from the so-called TOP10 group (Sci. Total Environ. IF2023-2024=9.44, J. Environ. Manag. IF2023-2024=9.32) and relate to the pan-European plan to improve the ecological status of inland waters. The publication "Boulder ramps as a restoration measure: Increasing the resilience of mountain freshwater ecosystems to environmental changes," released in January this year, concluded the publication cycle dedicated to testing the effectiveness of applied restoration practices, both spontaneous, i.e., without direct technical interventions, as well as those resulting from the engineering activities of beavers, and finally as a result of human engineering actions.

The scope of community actions in the field of water policy is defined by the Water Framework Directive (WFD), i.e., Directive 2000/60/EC of the European Parliament and of the Council of 23 October 2000. The primary goal of the WFD is to preserve and improve the status of surface and groundwater, both in terms of quality and quantity. The Water Framework Directive is one of the most important responses to the observed degradation of rivers. The tasks resulting from the adoption of the WFD include the classification of waters, assessment of their status, and the necessity to implement programs to gradually achieve good ecological status for all European waters. The directive has significantly increased the importance of river and stream research. However, there are still significant knowledge gaps, primarily regarding the responses of fish and aquatic invertebrates to environmental changes, especially concerning flowing water ecosystems, and without intensifying scientific research, it will be difficult to identify appropriate actions to reverse degradation.

The team of Prof. Krzysztof Kukuła and Associate Prof. Aneta Bylak, from the Department of Ecology and Nature Protection, has been conducting scientific research for many years that aligns with the tasks outlined by the Water Framework Directive. These studies allow for the assessment of the effectiveness of applied restoration solutions and, most importantly, serve as a guide for catchment management institutions, showing how to restore the good ecological status of rivers and ensure access to clean water. The series of publications forming a coherent thematic block is an extensive package of recommendations and solutions that can indirectly or directly influence the improvement of the ecological status of flowing waters.

Without going far, the team analyzed the results of research initiated in the 1990s and compared them with new data collected in the suburban area of Rzeszów – in the Matysówka stream catchment. Forty years ago, the stream was heavily degraded, although the catchment was still outside the urban area. Today, despite the lack of direct actions aimed at its revitalization, the condition of the stream has significantly improved. The expansion of the sewage network, combined with the decline of agricultural activities and succession processes on former agricultural lands, initiated a spontaneous process of stream renaturation ("self-restoration"). The example of the Matysówka stream shows that economic transformations in suburban areas can create an opportunity to establish a valuable recreational area for city residents. However, additional revitalization and investment activities are necessary. Our authors emphasized that further improvement of the ecological status of the stream and its catchment, in conjunction with maintaining a habitat mosaic, can increase the possibility of utilizing so-called ecosystem services, including the provision of clean water, regulation of air quality and temperature in the city, and the provision of recreational areas.

An extension of the research on the Matysówka stream catchment was a project involving comprehensive studies in the northern suburbs of Rzeszów, on two streams differing in the scale of catchment transformation by humans and another "ecosystem engineer," the European beaver Castor fiber. The main goal of the research was to answer the question – whether and to what extent the engineering activities of beavers in a human-dominated landscape will positively affect the ecological status of the stream? The analysis included the character of catchment management, habitat parameters in the streams, including physico-chemical water parameters, sanitary indicators, benthic invertebrate communities, ichthyofauna, as well as amphibians, waterfowl, and plants. The potential of the beaver-influenced stream catchment to provide ecosystem services was also assessed. The beaver pond, along with the adjacent wet reed beds and wet meadows, became a new habitat "island" with many plant and animal species. Thus, in a human-dominated landscape, a place with valuable natural qualities was created. The positive impact of the European beaver's activities was also observed in the stream itself, where, as a result of the "purifying" role of the beaver pond, a significant improvement in water quality occurred. Scientists from the Department of Ecology and Environmental Protection proposed changing the approach to beaver dam and pond complexes and considering their possible positive impact on ecosystems in catchment management plans.

Today, even the Bieszczady Mountains, considered synonymous with "wildness" and "naturalness," are not free from threats. One of them may be forestry. As a result of long-term, comprehensive research in the International Biosphere Reserve "Eastern Carpathians," our employees indicated that although fine-grained sediments are a natural component of river systems, human activities can cause a dramatic increase in their quantity. In mountainous areas, the source of sediments disrupting the functioning of aquatic ecosystems is often forestry. In the published work, the authors tested the hypothesis that biocenoses in the studied streams would differ in the degree of distortion, depending on the intensity of forestry activities in the catchment. The authors demonstrated that the silting of mountain stream beds can disrupt the structure of trophic networks of entire ecosystems. At the same time, the work presented evidence of the positive impact of beaver presence in economically exploited forest areas. Beaver ponds, by accumulating sediments, prevent stream degradation and contribute to the restoration of the natural structure of biocenoses. Capturing and storing fine sediments in beaver ponds can accelerate the revitalization processes of mountain streams. The publication proposed an innovative approach to managing beaver dams and suggested that good forestry practices, especially in mountainous areas, should consider the engineering activities of beavers by preserving the dams and ponds they build.

The next step in analyzing the possibilities of improving the ecological status of Carpathian streams was comprehensive research on the response of biocenoses to the technical renaturation of stream beds. Transformations resulting from human activities have affected the catchments of many Carpathian rivers. The authors indicated that numerous barriers built by humans disrupt the ecological continuity of many watercourses, and it is necessary to remove these barriers or appropriately rebuild them. To assess the real effects of stream renaturation, the team led by Prof. K. Kukuła and Prof. A. Bylak conducted analyses of fish and aquatic invertebrate communities, which are excellent bioindicators of habitat conditions in river systems. The authors demonstrated the positive effects of using boulder ramps as technical solutions for the renaturation of small mountain streams. They proved that with properly designed and implemented measures to restore stream continuity, it is also possible to rebuild aquatic fauna habitats. In recommendations directed to environmental management institutions, the authors indicated that the assessment of the effects of river and stream catchment renaturation should be conducted in the long term. Only such an approach can allow for a reliable assessment of the effects of renaturation actions and, if necessary, the quick introduction of necessary corrections.

Publications from the discussed research cycle: Bylak A., Kukuła K., Ortyl B., Hałoń E., Demczyk A., Janora-Hołyszko K., Maternia J., Szczurowski Ł., Ziobro J. 2022. Small stream catchments in a developing city context: The importance of land cover changes on the ecological status of streams and the possibilities for providing ecosystem services. Science of the Total Environment 815, 151974. https://doi.org/10.1016/j.scitotenv.2021.151974. (TOP10, 200 pts.) Bylak A., Kukuła K. 2022. Impact of fine-grained sediment on mountain stream macroinvertebrate communities: forestry activities and beaver-induced sediment management. Science of the Total Environment 832, 155079, https://doi.org/10.1016/j.scitotenv.2022.155079. (TOP10, 200 pts.) Bylak A., Szmuc J., Kukuła K. 2023. Assessment of the viable effects of structural reconstruction of habitats in a mountain stream: a long-term study. Science of the Total Environment 905: 167230. https://doi.org/10.1016/j.scitotenv.2023.167230. (TOP10, 200 pts.) Bylak A., Kochman-Kędziora K., Kukuła E., Kukuła K. 2024. Beaver-induced restoration: an opportunity for sandy lowland streams in a human-dominated landscape. Journal of Environmental Management 351, 119799. 1603–1615. https://doi.org/10.1016/j.jenvman.2023.119799. (TOP10, 200 pts.) Bylak A., Szmuc J., Hałoń E., Kukuła K. 2025. Boulder ramps as a restoration measure: Increasing the resilience of mountain freshwater ecosystems to environmental changes. Science of the Total Environment 962: 178475. https://doi.org/10.101