<p>Human activities such as land use changes and ongoing climate changes are expected to affect the physical and chemical characteristics of water, its quality, and the ecosystem processes in these ecosystems. This study aimed to evaluate the independent and interactive effects of pH and temperature on microbial decomposition, caddisfly shredder consumption, and survival in Neotropical streams. We tested the following hypotheses: (i) pH and temperature would independently affect microbial decomposition and shredder activity, and (ii) their combined increase would produce interactive effects, reducing shredder consumption and survival. We found no significant influence of pH or temperature on microbial decomposition, suggesting that microbes in these systems are adapted to a wide range of environmental conditions. However, a synergistic effect of pH and temperature was observed on shredder consumption and survival, with the greatest activity occurring at circumneutral pH and reduced under elevated temperatures. These findings highlight the importance of considering multiple environmental stressors to understand ecosystem processes in neotropical aquatic environments, as well as to support actions for the sustainable management and use of water resources.</p>