| Summary: | Faecal pellets (FPs) produced by suspension feeders, notably larval blackflies (Diptera: Simuliidae), contribute significantly to the conversion and transport of organic matter in northern rivers. In this study we investigated the relative contribution of tributaries to the flux of FPs in a 7(th) order river in northern Sweden. The influx of FPs to the larger river was positively dependent on tributary sub-catchment area, stream order, channel width, proportion of lakes in the sub-catchment, and current velocity. The contribution was < 45 % of the flux in the large river, but generally it was well below 10% suggesting that the large river transport of FPs is produced within the main channel and not imported from the tributaries, although the latter may significantly support the suspension feeders with food material.
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