1. In ectotherms, anthropogenic warming often increases energy requirements for metabolism, which can either impair growth (when resources are limiting) or lead to higher predator feeding rates and possibly stronger top-down trophic interactions. However, the relative importance of these effects in nature remains unclear because: 1) thermal adaptation or acclimation could lower metabolic costs; 2) greater prey production at warmer temperatures could compensate for higher predator feeding rates; and/or 3) temperature effects on trophic interactions via altered biological rates could be small relative to other, temperature-unrelated human impacts on food webs. 2. Here, we examined effects of deforestation-associated warming on the minnow Enteromius neumayeri, occurring in both forested (cool) and deforested (warm) streams located inside or nearby an afrotropical rainforest. Combining approaches from physiological and community ecology, we quantified impacts of anthropogenic warming on the metabolism, growth, and trophic interactions of this tropical ectotherm. We then compared these effects with impacts of land use unrelated to temperature. 3. In a long-term laboratory acclimation experiment quantifying the temperature-dependence of growth and metabolism in E. neumayeri, warming increased metabolic rates and decreased growth (at a limited ration). We found no evidence of local (thermal) adaptation, with warming affecting farm and forest populations similarly. 4. Then, using mark-recapture methods to quantify impacts of warming on performance in situ, we found similar growth rates in fish from deforested and forested streams despite their distinct thermal environments. This suggests higher prey consumption at deforested sites to compensate for greater metabolic costs, which could strengthen fish-invertebrate interactions. 5. Finally, we developed a bioenergetics model to estimate fish-invertebrate interaction strength and quantify temperature-related and unrelated impacts of land use on this interaction. We found that although warming increased fish consumption, it apparently increased invertebrate production even more and thus had a net weakening effect on estimated interaction strength. Most importantly, variation in both fish and invertebrate density not directly related to temperature had a much stronger influence on estimated interaction strength than temperature effects on predator consumption and prey growth.
6. We conclude that ectotherms can sometimes offset the metabolic costs of warming with a small increase in consumption that hardly effects food web interactions compared to non-metabolic impacts of anthropogenic disturbances. Future research should assess whether this is a common feature of heavily-impacted ecosystems facing multiple stressors.