b'Catchments of Conservation Concern: Sediment Flux andProvenanceONeill K1,2, Rowan JS2, Finn JA1 andhUallachin D11Crops, Environment and Land Use Programme, Teagasc, Johnstown Castle EnvironmentResearch Centre, Wexford, Co. Wexford, Ireland2School of Social Sciences, University of Dundee, Dundee, UKSediment pollution is a potential factor in the decline of the freshwater pearl mussel, asediment-sensitive species that has undergone dramatic population decline throughout its range in the 21st century. Although annual suspended sediment yields (SSYs) have been estab-lished for a number or Irish catchments, little is known regarding sediment yield in very extensivecatchments, hosting populations of sediment-sensitive species. The aim of the study was to collect data on the flux of sediment in priority conservation catchments, and data on theprovenance of the sediment. High-resolution, continuous monitoring of suspended sediment concentrations in threefreshwater pearl mussel catchments (the Bridia 22 km2; the Kealduff 26 km2; and the Owenroe 30 km2), with varying levels of land-use and land-cover, and mussel recruitment was undertaken. Suspended sediment yield was calculated from calibrated turbidity, discharge and modelled data. Sediment fingerprinting, using natural soil and sediment characteristics, was used to identify sources of sediment. Estimated annual suspended sediment yields were 2.7 t km-2 year-1 for the Owenroe, 2.8 t km-2 year-1 for the Kealduff catchment; and 5.6 t km-2 year-1 for the Bridia catchment. These yields are low in the context of contemporary European yields, however results suggest that duration and timing of (relatively) high sediment concentrations may be more relevant to conservationstrategies than overall yields.Results showed seasonal fluctuations in sediment sources and yield in the study catchments e.g. 90% of the total yield in the Kealduff catchment was transported during <1% of the time. Forestry was a dominant source in the catchment containing a significant conifer plantation, while key sources in other catchments ranged from extensive areas to improved grassland and roadverges.The study can contribute to the development of ecosystem-based mitigation measures that both aid the restoration of endangered species and provide broader sustainable land management benefits.28'