Once obscure, overlooked and underappreciated, the ecological role of freshwater mussels in lotic and lentic environments is increasingly being recognised. One of the important roles of mussels is as benthic-pelagic couplers: as filter-feeders, they transfer nutrients and energy from the water column to sediments through excretion and biodeposition of both faeces (digested material) and pseudofaeces (undigested material). The deposition and transformation of pelagic organic matter to the benthos can have a substantial influence on nutrient cycling and energy transfer in both lake and riverine ecosystems. Despite the Hyriidae being the second most diverse family of freshwater mussels, little is known about their ecology. As far as we are aware, the effect of Hyriids as benthic-pelagic couplers has yet to be assessed. The aim of this research was to explore aspects of the functional role of riverine hyriids, and to estimate the potential impact in-situ mussel populations can have on key ecological processes such as biofiltration, nutrient retention, habitat provisioning and pelagic-benthic coupling. We did this in four parts: 1) we calculated biodeposition and excretion rates of key nutrients (C,N,P), and organic matter by the river mussel, Alathyria jacksoni, in a unregulated river in south-eastern Australia; 2) we ran in situ mesocosm experiments to examine if the physical structure and bio-deposition of A. jacksoni influenced the distribution and abundance of organisms in their nearby benthic environment; 3) we conducted laboratory experiments to estimate filtration rates and biodeposition rates of A. jacksoni under varying suspended sediment concentrations; and 4) we combined the process rates derived from these studies with estimates of the population size of A. jacksoni from the lower Ovens River, and calculated the potential impact a mussel populations on key ecological processes in rivers at the riverscape scale. We discuss our results in light of the role that mussels may have in riverine environment, and in the context of global declines in native freshwater mussels generally.