Stream temperature varies widely seasonally and spatially, and may regulate the strength of community interactions via direct effects on biotic metabolism.  Previous research indicates different optimal temperatures for two important prairie stream omnivores, the southern redbelly dace Phoxinus erythrogaster and the crayfish Orconectes spp. (17 and 22^oC, respectively).  We predicted dace would have a greater effect on producer biomass and production than crayfish at lower temperatures, and the opposite at higher stream temperatures.  Two temperature levels (high and low; means=15.3 and 10.9 ^oC, respectively) and four consumer levels (a no consumer control, dace, crayfish, or both consumers) were factorially crossed in outdoor experimental streams (n=3 replicates per treatment combination).  After 30 days, streams containing both consumers had greater periphyton biomass than controls (mean+1SE =75.1+12.8 and 28.9+2.7mg chla/m^-2 respectively) or each consumer alone (dace=40.6+3.0mg; crayfish=30.5+7.5mg chla/m^-2) at high, but not at low temperatures (p=0.045).  Dace alone stimulated mean algal filament length only at high temperatures (p=0.017; mean+1SE dace=229+8cm; control=29+14cm).  Dace stimulated whole-system productivity in the absence of crayfish regardless of temperature (p=0.001; mean+1SE dace=1.35+0.12 mgO₂/m^-2/d^-1; control=1.22+0.11 mgO₂/m^-2/d^-1).  Our study suggests that species functions and interactions in prairie streams may be partially regulated by temperature.