| Abstract [eng] |
Urban rivers are increasingly exposed to multiple stressors associated with land use change, yet effective tools for assessing their ecological condition remain essential for sustainable management. This study evaluated the potential of zoobenthic communities as bioindicators of water quality along an urbanisation gradient in the Nemunas River within the city of Kaunas, Lithuania. Sampling sites were selected across natural, urban centre, and peripheral areas to examine spatial variation in benthic macroinvertebrate communities in relation to physico-chemical parameters. Ecological status was assessed using the River Macrofauna Index (UMI), alongside measurements of pH, water temperature, conductivity, nutrients, chlorophyll, chloride, as well as flow velocity. UMI values were highest in natural and semi-natural areas and lowest in peripheral sections, supporting the hypothesis that urbanisation negatively influences zoobenthic community structure. Urban centre sites exhibited relatively consistent, intermediate UMI values. A significant negative relationship between UMI and both chloride concentrations was revealed, indicating the importance of ionic pollution as a driver of ecological degradation in urban rivers. Other physico-chemical parameters showed weak or non-significant relationships with UMI. Significant differences were found between seasons in metahabitat analysis, which showed homogenisation in autumn, and higher diversity in spring. Zoobenthic assemblages were dominated by invasive species, particularly Pontogammarus robustoides (Sars, 1894), which are not accounted for in UMI calculations and may influence interpretations of ecological status. Overall, the results demonstrate that zoobenthic communities can effectively reflect spatial patterns in water quality along urbanisation gradients, while also highlighting the need to refine bioassessment approaches to account for invasive species and urban-specific stressors. |
