Linking trophic ecology and metal bioaccumulation to assess a widespread fish as a bioindicator following a...

Fish are key bioindicators for understanding the impacts of human-induced environmental disasters. We assessed trophic ecology and metal accumulation (Fe, Mn, Hg) in the small and abundant characid Astyanax lacustris in the Doce River basin, following the 2015 mining tailings dam collapse. Stable isotope and metal analyses were conducted in fish from six affected sites and two reference sites. Aquatic invertebrates dominated the diet, except near the dam rupture, where algae predominated, and metal concentrations were highest. Fe and Mn concentrations decreased with fish length, Hg increased with fish nitrogen isotopic composition (δ¹⁵N), and only Fe showed clear associations with dietary sources. This study is novel in integrating trophic ecology and metal contamination assessment in a sentinel fish species after a major mining disaster. The findings provide insights for biomonitoring and metal risk assessment in freshwater ecosystems worldwide, and highlight Astyanax lacustris as a powerful sensitive bioindicator, reflecting both contamination legacy and ecological pathways of metal accumulation.