Análise comparativa de ecotoxicidade aguda em Biomphalaria glabrata e Lymnaea stagnalis (mollusca: gastropoda) expostas ao cloreto de cádmio

Abstract

Cadmium chloride (CdCl2) is a salt that has high solubility in water and is frequently adopted as a reference substance in laboratory ecotoxicological assays. Several institutions have been standardizing tests to define toxicity thresholds to protect organisms and ecosystems. Invertebrates are frequently used in these evaluations, and mollusks, the second largest animal group, are suggested as appropriate models. Standardizing ecotoxicological assays with native species is necessary, since in the majority of cases, they are more susceptible to environmental contamination than exotic species, and thus, validating tests with ecological and environmental representativeness in different countries is essential. The objective of this study was to compare and evaluate the sensitivity of the Brazilian native freshwater snail Biomphalaria glabrata (Say, 1818) and the European standard species Lymnaea stagnalis (Linnaeus, 1758), by analyzing the acute toxic effect of CdCl2. The survival of adult’s snails of the species B. glabrata and L. stagnalis was evaluated through 24- hour exposure to concentrations of 0.00; 0.12; 0.25; 0.50; 1.00 and 2.00 mg L-1 of CdCl2. The lethal concentration (LC50) for adult organisms was 0.48 mg L-1 for B.

glabrata and 0.33 mg L-1

for L. stagnalis. With the ecotoxicological assays carried out, it was possible to establish physical-chemical parameters and comparatively evaluate the sensitivity of L. stagnalis and B. glabrata, it was possible to show that B. glabrata was responsive and had similar results to L. stagnalis. For standardization procedures in countries that require the regulation of new tests, the comparison between organisms already validated worldwide is an additional motivation to employ them for the implementation of tests with endemic species in countries such as Brazil.