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When evaluating biological recovery, shifts in species identity such as non-native status, specialisation, and functional traits should be examined alongside changes in species richness. Lithuania, an ecologically overlooked region, serves as a crucial reservoir for boreal and glacial relict macroinvertebrates. We investigate how and why Lithuanian riverine communities have changed during the intensive period of global environmental changes from 2010 to 2020. Using 41 time-series from Lithuanian rivers, we identified changes in taxonomic and functional diversity. Akin to biological recovery, we observed an overall increase in both taxonomic and functional diversity, likely due to improved water quality, evidenced by increased dissolved oxygen levels and reductions in toxic nitrogen and phosphorus products. However, increases in the richness and abundance of insect and indicator taxa were superseded by increases in non-insect taxa, including crustaceans, molluscs, and annelids. These compositional changes were attributed to climatic changes, notably rising temperatures and reduced discharge. Biodiversity responses to environmental changes were stronger in larger rivers, which are economically important and represent sentinels for further upstream changes. While improvements in water quality benefit various stakeholders and should continue, prioritising mitigation of global environmental change should be the top priority for global cooperation and management schemes. [ABSTRACT FROM AUTHOR]

Lake shores are characterised by a high natural variability, which is increasingly threatened by a multitude of anthropogenic disturbances including morphological alterations to the littoral zone. The European Water Framework Directive (EU WFD) calls for the assessment of lake ecological status by monitoring biological quality elements including benthic macroinvertebrates. To identify cost- and time-efficient sampling strategies for routine lake monitoring, we sampled littoral invertebrates in 32 lakes located in different geographical regions in Europe. We compared the efficiency of two sampling methodologies, defined as habitat-specific and pooled composite sampling protocols. Benthic samples were collected from unmodified and morphologically altered shorelines. Variability within macroinvertebrate communities did not differ significantly between sampling protocols across alteration types, lake types and geographical regions. Community composition showed no significant differences between field composite samples and artificially generated composite samples, and correlation coefficients between macroinvertebrate metrics calculated with both methods and a predefined morphological stressor index were similar. We conclude that proportional composite sampling represents a time- and cost-efficient method for routine lake monitoring as requested under the EU WFD, and may be applied across various European geographical regions. [ABSTRACT FROM AUTHOR]

Although the assembly of stream macroinvertebrates is regulated by environmental heterogeneity at multiple spatial scales, field bioassessment studies that explicitly considered such scale-dependency are rare. Here, we investigated how large scale longitudinal gradients and local microhabitat structure jointly regulate the assembly of macroinvertebrate communities along a Mediterranean river. We compared community composition, metrics and functional feeding traits among three microhabitat categories (grain-size >20 cm; grain-size <20 cm; organic substrata) along three river sectors (up-, middle-, downstream), which reflected a gradient of anthropogenic modification. Macroinvertebrate assemblages varied mostly over the large-scale longitudinal gradient, but the influence of local micro-habitat features was evident at the within-sector scale. The effects of micro-habitats appeared stronger for feeding traits compared to simple taxonomic metrics, supporting the hypothesis that feeding traits are sensitive to river substratum character. Beta-diversity among micro-habitat types was smaller in the modified downstream sector, which supported more homogeneous communities. An explicit consideration of spatial scales is recommended when interpreting results from environmental assessment studies. In the Aniene River, the influence of local-scale substratum character on macroinvertebrates depended on the longitudinal gradient in anthropogenic pressure. Also, the findings suggest that taxonomic and functional metrics reflect processes operating at different spatial scales. [ABSTRACT FROM AUTHOR]