Annual migrations of anadromous salmon are an important nutrient source for many coastal streams. Much of the current research has focused on nutrient retention via carcass consumption by mammals, birds, and macroinvertebrates; the retention of nutrients by microbiota has received less attention. We measured retention of salmon-derived nutrients by aufwuchs and bryophyte communities in 12 artificial channels (0.2 m x 1.2 m). Intact salmon pieces (2.1 kg/m2) were randomly placed in 6 channels; 6 channels receiving no salmon. All channels contained unglazed tiles for aufwuchs colonization and cobbles with bryophytes from a local stream with no salmon migration. The channels were allowed to run for 75 days at 0.01-0.02 L/sec and 15:9 hr light/dark cycle. There were significant differences between treatments for dissolved concentrations of orthophosphate, total phosphorus, total nitrogen, nitrate, and ammonium. The aufwuchs in the salmon channels contained higher AFDW and chlorophyll concentrations; higher dN15 levels and phosphorus concentration, and lower C:N ratios. The salmon channel bryophytes contained higher dN15 levels and phosphorus concentrations, and lower C:N ratios. These results indicate that stream microbiota are successful at recapturing and retaining both dissolved nitrogen and phosphorus that would otherwise be lost downstream.