Supplementary information files for "Taxonomic and trait-based approaches for monitoring fine sediment: influence of sediment method, substrate composition, taxonomic resolution and spatial scale"

Supplementary files for article "Taxonomic and trait-based approaches for monitoring fine sediment: influence of sediment method, substrate composition, taxonomic resolution and spatial scale"

Excessive fine sedimentation (particles <2 mm) is a key stressor for aquatic biodiversity globally, impairing habitat quality and ecological function in freshwater ecosystems. Effective monitoring tools are critical for identifying areas where management interventions can reduce fine sediment inputs to river systems. In this study, we evaluated how seven widely used fine sediment measurement methods influence the detection of ecological impacts on benthic invertebrate communities across 29 river sites in England and Wales. We tested how associations between sediment and invertebrate metrics varied by sampling mode (quantitative vs. semi-quantitative; surface vs. subsurface), spatial scale (reach vs. patch), taxonomic resolution, and substrate composition (cobble, pebble, granule). Our results suggest that whilst significant associations were detected at the patch scale, the strength of these were generally greater at the reach scale. Fine sediment methods were more strongly correlated with invertebrate metrics in granule sites, with reduced strength of association in cobble grained sites. Sediment-specific indices showed the most consistent association with the different sediment methods, but demonstrated the strongest association in granule-dominated sites. Bed surface measurements were more strongly associated with invertebrate metrics than subsurface techniques. Rapid resuspension-based approaches performed comparably to more resource intensive methods, offering practical alternatives for large-scale monitoring. Functional diversity metrics showed limited sensitivity to fine sediment, and species-level identification did not improve metric performance (compared to family-level). Overall, our findings highlight the importance of aligning sampling methods with local sampling context, particularly spatial scale and substrate type, when using macroinvertebrates to assess the ecological impacts of fine sediment.

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