Species-area (SA) and biodiversity-ecosystem function (BEF) relationships are fundamental pillars of ecological systems. SA theory predicts that species richness within a habitat increases with habitat area, and BEF theory predicts that metrics of ecosystem function increase with, or show a hump-shaped response to, species richness. Further, the river continuum concept (RCC) predicts that biological communities in smaller streams should be dominated by disturbance-tolerant species, while communities in larger streams should be dominated by species adapted for more stable conditions due to differences in disturbance frequency. Freshwater mussels are sedentary bivalves that form patchily distributed aggregations in streams, thus providing the opportunity to test predictions from SA, BEF, and RCC theory. We tested for SA relationships using recent and historic quantitative mussel survey data from western Alabama, USA. Mussel-generated BEF impacts on ecosystem functions such as primary production and ecosystem metabolism are well-documented, but there is no thorough understanding of mussel-generated secondary production (SP) in streams, so we also tested whether areal SP and biomass increased with species richness. We then used a life history strategy framework to test the RCC prediction that disturbance-tolerant taxa would dominate areal SP and biomass at upstream sites, and species adapted to more stable conditions would dominate SP and biomass further downstream. We found support for both SA and BEF relationships. We also found support for the RCC, as increases in areal SP also corresponded to a shift in the life history strategies of species generating production. At upper-watershed sites, SP was generated primarily by fast-growing, short-lived species. Slow-growing, longer-lived species generated most of the SP lower in the watershed. Species with high SP values were not necessarily the dominant components of assemblage biomass. This underscores the utility that SP has over metrics of biomass and abundance when testing fundamental ecological predictions about ecosystem function.