The Ulba river basin is one of the most industrialized regions of Kazakhstan. The development of mining and metallurgical industries has increased pollution of the basin's surface waters by heavy metals, primarily zinc and copper. The taxonomical structure of Trichoptera was studied in reference and impacted reaches of the river basin. A significant decrease in Trichoptera species richness was recorded in the most polluted areas. A total of 35 species were identified at the reference site of the Breksa River, but only 14 in the impacted sites. Ceratopsyche newae, Dicosmoecus palatus, Glossosoma altaicum and Rhyacophila sibirica showed a significant reduction at sites with high heavy metal concentrations.
Keywords: Bioindication; Heavy metals; Mining; Trichoptera.