Ephemeroptera, Trichoptera, and Plecoptera with bioindicator potential in streams across a mosaic of land uses

Abstract Understanding how local environmental factors and seasonal variation shape aquatic insect communities is key for developing effective biomonitoring tools, especially in ecotonal regions undergoing rapid environmental changes such as the Brazilian Cerrado. In this study, we tested the hypotheses that (1) local environmental variables exert stronger influence than seasonality on EPT composition and (2) environmental gradients define ecological thresholds that affect the abundance and occurrence of sensitive genera, indicating their bioindicator potential. Using redundancy analysis and threshold indicator taxa analysis—TITAN, we found that pH, conductivity, and stream width significantly influenced assemblage composition. TITAN revealed abrupt changes in the abundance of genera such as Guajirolus (Baetidae) and Macrostemum (Hydropsychidae). Although seasonal variation had a smaller effect, it still influenced taxonomic richness. Our results emphasize the importance of local environmental filtering on EPT assemblage structure and suggest that these taxa can be effective indicators of stream habitat integrity, which can be an important tool for monitoring local streams that have currently suffered intense anthropization. We recommend future studies to expand taxonomic resolution, include additional variables such as dissolved oxygen, and consider broader conservation gradients and temporal scales to enhance the detection of robust bioindicator taxa in tropical streams.