Light levels and temperature are strongly correlated in most ecosystems (i.e., highest during summer and lowest in winter). Because of this near-ubiquitous correlation, it is difficult to isolate the individual effects of light and temperature on ecosystem processes under natural conditions. Arctic spring-streams provide an exception due to their relatively constant water temperatures combined with extreme annual light fluctuations, which effectively uncouples their annual light and temperature regimes. We collected samples of basal resources (i.e., aquatic bryophytes and biofilms) semi-monthly from five spring-streams that vary in source temperature from ~1 to 13°C. We measured the activity of carbon (C), nitrogen (N), and phosphorus (P) eco-enzymes and the % C, N, and P contents of both basal resources to assess seasonal patterns in their nutrient limitation and demand. While there were no strong temperature effects, both bryophytes and biofilms showed seasonal patterns for all three enzymes, with the highest activity occurring in summer and lowest in winter. Strong limitation by P was indicated for both bryophytes and biofilms, whereas only biofilms showed N limitation. At the whole-stream scale, bryophytes produce more C- and P-processing enzymes, as a function of their high biomass, but biofilms produce more N-processing enzymes, indicating a greater relative importance in ecosystem-level N cycling. We will also present data on the stoichiometry and elemental threshold ratios for each group. Comparison of nutrient acquisition strategies by the two major basal resources found in arctic spring-streams helps disentangle their relative contributions to ecosystem-level processes, while their seasonal patterns and thermal responses inform understanding of light and temperature as drivers of ecosystem dynamics.