Leptodactylus macrosternum (Anura: Leptodactylidae) as a bioindicator of potentially toxic chemical elements in irrigated perimeters in northeastern Brazil

Biomonitoring programs have developed in the last decades, including the toxicity evaluation of endemic organisms in populations from polluted areas. Environmental bioindicators respond to contaminants as predictors of future damage to their population, ecosystem and human. Amphibian are considered very sensitive contamination bioindicators. Researchers in several continents have conducted ecological studies on the accumulation of potentially toxic elements in anuran tissues, especially in mining and agriculture areas. The Jaguaribe River is an important water source in northeastern Brazil, home of agriculture irrigated perimeters; but it also concerns users for increasing the risks of environmental contamination. The objective of this work was to quantify potentially toxic elements in Leptodactylus macrosternum carcasses, evaluating its potential as a contamination bioindicator of agrosystem areas in the Lower Jaguaribe River basin, Ceará, northeastern Brazil. The elements As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn were detected in the L. macrosternum carcasses' samples. There was no significant difference in the concentrations of detected metals by area status; however, analysis of variance suggested that individuals had more constant exposure to Cu, Ni, Cd and Pb in cultivated area status. The cluster analysis of chemicals indicated two optimal element groups, which proposed different compounds from diverse origins. Body index significantly influenced Mn and Pb, while sex influenced Fe and Pb accumulation. The results suggested that the L. macrosternum species is a conceivable local bioindicator for environmental potentially toxic elements. However, other tissues will be tested to improve their sensitivity and validate their capacity to be employed as a biomonitoring tool.