Anthropogenic warming of high-latitude stream ecosystems is influencing the energy budgets of aquatic organisms, with important implications for the movement and storage of energy and materials in food webs. Although acute exposure to higher temperatures often leads to reduced growth efficiencies (i.e., the proportion of ingested or assimilated resources that contribute to biomass production), bioenergetic plasticity in response to long-term warming may allow partial or complete metabolic compensation, thus allowing some populations to persist at higher temperatures. We conducted a reciprocal transplant experiment of Eukiefferiella minor (Diptera: Chironomidae) across a natural stream geothermal gradient (5°C - 22°C) in southwestern Iceland to test the hypothesis that organisms acclimated or adapted to chronic warming will exhibit higher energetic efficiencies than organisms chronically exposed to lower temperatures, via an elevated growth to respiration ratio. Our preliminary results show that individuals from warmer streams had higher mass-specific growth rates and down-regulated respiration rates compared to individuals from colder streams across the range of temperatures, which indicates partial compensation of E. minor in response to chronic warming. These results, together with complementary efforts at our study site, imply that bioenergetic plasticity is a potentially significant factor in determining how aquatic organisms respond to warming, and can influence trophic transfers of energy in aquatic food webs.