Tadpoles assay: its application to a water toxicity assessment of a polluted urban river.

The acute toxicity assay with premetamorphic tadpoles of Bufo arenarum as sentinel organism was applied to evaluate the quality of two water samples taken from three sites of theReconquista River, an urban watercourse which is recipient ofboth untreated industrial effluents and domestic wastes. Theresults of the 96 hr bioassays were compared with thephysicochemical parameters determined in the samples.Mortality rates in each sample were compared using the Bonferroni's test and a stepwise regression analysis of mortality andphysicochemical parameters was done. In this way, it was possible to build up consistent descriptive models which showedthat pH, Cl-, Cd2+ and Cu2+ concentrations in theriver water were significant independent variables and mightexplain, under the experimental conditions, the recordedtoxicity effects of the tested samples.Because of its simplicity, low cost and reliability it wassuggested the tadpoles bioassay be included in the set of testsused in integrated program of freshwater pollution.